Three Tier Unmanned Aerial Vehicle, Strategic Roles and
Mechanical Design
by
Alankar Chhabra
B.S., Mechanical Engineering (1998)
Massachusetts Institute of Technology
SUBMITTED TO THE DEPARTMENT OF AERONAUTICAL & ASTRONAUTICAL
ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF ENGINEERING IN AERONAUTICAL & ASTRONAUTICAL ENGINEERING
AT THE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
MAY 1999
© 1999 Massachusetts Institute of Technology.
All rights reserved
Signature of Author.............
........
. ...... . ............
...
Department of Aeronautical & Astronautical Engineering
May7, 1999
Certified by .......................
.. t..e...
""o
. ... ..
/
ol. Peter Young
Visiting Lecturer of Aeronautical & Askonaucal Engineering
,
~I~Thesi Supervisor
\
S
j A
Charles W. Boppe
Senior Lecturer
Thesis Advisor
Accepted by.......................
Jaime Peraire
Professor of Aeronautical & Astronautical Engineering
Chairman, Committee for Graduate Thesis
MASSACHUSETTS INSTITUTE
OF TECHNOLOGY
,JUL 1
1999
Three Tier Unmanned Aerial Vehicle, Strategic Roles and
Mechanical Design
by
Alankar Chhabra
Submitted to the Department of Aeronautical & Astronautical Engineering
On May 8, 1999 in Partial Fulfillment of the Requirements for the
Degree of Master of Engineering in Aeronautical & Astronautical Engineering
ABSTRACT
This thesis documents the systems approach, strategic role and mechanical design
elements of a three-tier unmanned aerial vehicle prototype being developed by the
MIT/Draper Technology Partnership. This parent-child concept incorporates three
classes of Unmanned Aerial Vehicles (UAVs). A parent vehicle of 3.4-meter wingspan
is maintained at the mother level while a mini-vehicle of one-meter wingspan and microvehicles of six inches maximum dimension make up its children. Because of this
hierarchical structure, the aerial system designed and developed has been named the
Parent-Child Unmanned Aerial Vehicle (PCUAV).
Two major components of the PCUAV system are covered extensively in this document.
The first component consists of the systems engineering approach used in the research
and development of the vehicle system. This section presents why a PCUAV system is
needed and what strategic roles are to be performed by the vehicle. The PCUAV is a
novel concept designed to be used as an intelligence-gathering tool for platoon-sized
units, Navy ships, and numerous commercial applications. It is designed for
incorporation into both military and commercial missions and is to be deployed in both
urban and suburban settings. Such a system will perform missions in reconnaissance,
bomb damage assessment, micro aerial vehicle deployment and communication, and
other unspecified applications. This UAV is designed to be two-man portable, allow
short takeoff and landing, and be adaptable to various types of environmental conditions.
The second component of this document consists of the preliminary vehicle design and
development. This component that takes the concept to a preliminary design stage will
lay the foundation for a future design and build of a PCUAV.
The prototype vehicle described in this thesis is designed to verify the PCUAV systems
concept and to study its mechanical structure and layout. Its development and design is
part of a two-year joint venture by Massachusetts Institute of Technology and the Charles
Stark Draper Laboratory.
Thesis Supervisor: Col. Peter Young
Title: Visiting Lecturer of Aeronautical & Astronautical Engineering
Acknowledgments
I would like to thank and acknowledge the following people for their valuable
contributions to this project.
I would like to thank my thesis supervisor, Col. Peter Young, for the guidance and
aid in the development of such a novel concept.
I would also like to thank my project advisors, Mr. Charles W. Boppe and Prof.
John Deyst, for the direct support and direction. Thank you for giving me the
opportunity to be a member of the MIT/Draper partnership team.
Finally, I would like to thank my father for helping me and for giving me some
great guidance through the last twenty-three years and counting. Without your help and
support I would have never reached this milestone in my academic career.
Contents
ABSTRACT .................................................................................................................
2
LIST OF TABLES ....................................................................................................
6
LIST OF FIGURES ....................................................................................................
6
1.0 INTRODUCTION ................................................................................................
8
1.1 MIT/DRAPER PARTNERSHIP ...............................................................................
8
1.2 U A Vs
...............................................
1.2.1 Predator U A V .................................................................................................................
1.2.2 G lobal H awk UA V ............................................. ......................................................
1.2.3 Sender U A V ...................................................................................................................
9
10
12
14
1.3 MICRO ARIAL VEHICLES ..............................................................
15
1.4 NEED FOR A PCUAV VEHICLE .........................................................
19
1.4.1 Potential A dvantages ......................................................................... ....................... 19
1.4.2 Applications ............................................................... ............................................... 20
1.5 THESIS OBJECTIVES ........................................
.....................................................
22
2.0 PROBLEM DEFINITION & STRATEGIC ROLES ......................................
23
2.1 SCOPE OF THE PCUAV PROJECT .............................................................................
23
2.2 CUSTOM ER N EEDS.......................................... ......................................................... 24
2.3 SYSTEM REQUIREMENTS .............................................................. 25
2.4 REQUIREMENTS PRIORITIZATION..................................................
27
3.0 VEHICLE CONCEPT STUDY ............................................................................
29
3.1 ARCHITECTURE TRADE STUDY PROCESS................................
29
3.1.1 Architecture 401: The Preferred System Concept ......................................
.....
3.2 PCUAV MEETS REQUIREMENTS ........................................................
3.2.1 Three-Tier System ........................................................................... .........................
3.2.2 Strategic M issions...................................................... ...............................................
3.2.3 Potential Users .............................................................................. ............................
3.3. PCUAV MISSION SCENARIOS .........................................................
29
31
31
34
34
34
3.4 COMPETITORS ................................................
42
3.5 MECHANICAL DESIGN CONSIDERATIONS AND CONSTRAINTS ................................... 43
4.0 VEHICLE PRELIMINARY DESIGN ........................................
4.1 SYSTEM OUTLINE ..........................................
.........................
44
.......................................................... 44
4.2 VEHICLE G EOM ETRY .............................................
.................................................. 44
4.2.1 Parent Vehicle Configuration ...........................................................
44
4.2.2 Parent Vehicle Internal Component Packaging .......................................
..... 48
4.2.3 M ini-V ehicle C onfiguration ................................ .................................................... 49
4.3 INTEGRATED DESIGN...........................................................................................
50
5.0 PARENT-CHILD INTEGRATION DESIGN .......................................
55
.....
5.1 MINI DEPLOYMENT ....................................................................
5.2 INTEGRATED FUEL/SEPARATION SYSTEM ........................................
5.3 RENDEZVOUS .................................................
55
............... 55
60
6.0 SUMMARY AND RECOMMENDATION .........................................................
65
6.1 PROTOTYPE .................................................................................................................. 65
6.2 FUTURE EFFORT .......................................... ............................................................ 65
6.3 COST .................................................
67
6.4 CONCLUSIONS .............................................................................................................. 68
6.5 RECOMMENDATIONS ...................................................................
68
REFERENCES ................................................................................................................
70
APPENDIX
APPENDIX
APPENDIX
APPENDIX
A PPENDIX
APPENDIX
APPENDIX
APPENDIX
APPENDIX
72
73
74
75
77
79
81
A
B
C
D
E
F
G
POWER/PROPULSION STUDY ..........................................
...........
TUBE LAUNCH FOR PCUAV....................................................................
CHILDREN PACKAGING ON PARENT .......................................
...........
DRAPER GROUND STATION .......................................
SYTEM S .......................................... ..........................................................
PCUAV WRINKLES ........................................
PCUAV-STINGER MISSILE ...........................................
...................
H SENDER TRIP REPORT ................................................................................
I MOTOR TABLES ................................................................
82
84
List of Tables & Figures
TABLE 1.2.1
TABLE 2.3.1
TABLE 2.4.1
TABLE 3.1.1
TABLE 3.2.1
TABLE 5.3.1
INITIAL UAV TRADE STUDY ..........................................
...........
STRUCTURING CUSTOMER NEEDS................................................................
REQUIREMENT PRIORITIZATION .....................................................................
TRADE MATRIX DERIVATION OF THE CONCEPT...........................................
PRODUCT ATTRIBUTE MATRIX.......................................
...................
RENDEZVOUS CABLE ANALYSIS .........................................
...............
16
26
27
30
32
64
FIGURE 1.2.1 PREDATOR UAV........................................................
10
FIGURE 1.2.2 GLOBAL HAWK UAV ..........................................................
12
FIGURE 1.2.3 H A E MISSION ........................................... .............................................. 13
FIGURE 1.2.4 SENDER U A V ...............................................................
........................... 14
FIGURE 1.3.1 MICRO AERIAL VEHICLES. ..........................................
................. 18
FIGURE 1.4.1 PCUAV - POTENTIAL MISSIONS - VERSATILITY ....................................... 22
FIGURE 2.1.1 SCOPE OF THE PCUAV PROJECT .........................................
............ 23
FIGURE 2.4.1 TOP SYSTEM REQUIREMENTS FOR PCUAV ......................................
28
FIGURE 3.2.1 PCUAV CLASSES ............................................................... 32
FIGURE 3.2.2 PCUAV SCOPE ...............................................................
33
FIGURE 3.2.3 PCUAV CLASSIFICATION BY SIZE .......................................
........... 34
FIGURE 3.2.4 POTENTIAL USERS .............................................................
35
FIGURE 3.3.1 POTENTIAL T/O MISSIONS...................................................
36
FIGURE 3.3.2 POTENTIAL DEPLOYMENT MISSIONS .......................................
......... 37
FIGURE 3.3.3 MULTIPLE DATA COLLECTION .........................................
.............. 38
FIGURE 3.3.4 POTENTIAL MISSIONS - DATA RELAY...................................
............ 38
FIGURE 3.3.5 POTENTIAL MISSIONS - VERSATILITY ...................................... ......... 39
FIGURE 3.3.6 POTENTIAL MISSIONS - HARMS WAY .......................................
........ 41
FIGURE 3.3.7 POTENTIAL MISSION - LANDING ........................................
............
42
FIGURE 4.2.1 INITIAL PARENT STRUCTURE LAYOUT........................................................ 45
FIGURE 4.2.2 LIFT FORCE ON PARENT VEHICLE................................................................. 46
FIGURE 4.2.3 SKIN FRICTION COEFFICIENTS ..........................................
.............. 47
FIGURE 4.2.4 PARENT VEHICLE INTERNAL COMPONENT PACKAGING ............................. 49
FIGURE 4.2.5 LIFT FORCE ON THE MINI-VEHICLE .......................................
.......... 49
FIGURE 4.3.1 FIXED WING MINI-VEHICLE................................................................
50
FIGURE 4.3.2 ALL WING MINI-VEHICLE (DIMENSIONS IN CM) ..................................... 51
FIGURE 4.3.3 PARENT-MINI INTEGRATION (BOTH FIXED WING) ..................................... 52
FIGURE 4.3.4 PARENT-MINI INTEGRATION (BOTH ALL WING) ......................................
53
FIGURE 4.3.5 INTEGRATION CONCEPTS ...........................................
............. 54
FIGURE 5.2.1 PARENT-MINI SEPARATION SYSTEM (SIDE VIEW - DIMENSIONS IN CM)......... 56
FIGURE 5.2.2 PARENT-MINI SEPARATION SYSTEM (FRONT VIEW - DIMENSIONS IN CM) ...... 56
FIGURE 5.2.3 DETAILED PARENT-MINI SEPARATION SYSTEM .....................................
57
FIGURE 5.2.4 FUEL SYSTEM .......................................................................................
58
FIGURE 5.2.5 EMBEDDED APPROACH ................................................................................. 59
FIGURE 5.2.6 PARENT-MINI FREE BODY DIAGRAM .......................................
.......... 59
FIGURE 5.3.1
FIGURE 5.3.2
FIGURE 5.3.3
FIGURE 5.3.4
FIGURE 6.2.1
CONTROLLABLE DROGUE (WITH AIRFOIL).............................
PASSIVE DROGUE (BASED ON C130 DESIGN) ..................................................
DROGUE CAPTURE ..............................................................
MINI RENDEZVOUS SYSTEM...............................
...........................
STATE OF UAVs ...............................................................
61
61
63
63
67
CHAPTER 1
Introduction
There has been a growing interest, in the past few years, in designing and
developing small Unmanned (uninhabited) Air Vehicles (UAVs). These electromechanical systems conduct unmanned operations for the direct use of human beings,
while keeping them from harms way. While humans may assist, they are not at a direct
risk during the conduct of these operations. Such vehicles can be efficient and
inexpensive tools for collecting information in dangerous or hostile environments. For
instance, equipped with a camera, a UAV could be used in a short duration surveillance
or reconnaissance mission of interest to the military. These UAVs are currently being
used for a small yet expanding branch of military technology intended to tackle problems
that humans alone cannot solve. Present research in the field is aimed at making these
vehicles low-cost, small, and with greater intelligence and autonomy. (Ref. 1)
1.1
MIT/DRAPER Partnership
The Massachusetts Institute of Technology (MIT)/Charles Stark Draper Laboratory
(Draper) Partnership was started in 1996 with a goal to develop and demonstrate an
innovative first-of-a-kind system judged to be important to our national needs. This
partnership includes and is led by selected MIT faculty in the Aeronautics and
Astronautics department and by selected Draper technical staff members. A MIT student
team is made from several Master of Engineering students, Master of Science students
and Undergraduates in the Aeronautics and Astronautics department. Professor John J.
Deyst and Senior Lecturer Charles W. Boppe head the PCUAV project. Other MIT
faculty supporting the project includes Col. Peter Young, and Professor John Chapin.
The primary Draper Engineers involved in the project include Dr. Brent Appleby and Mr.
Richard Martorana.
In order to develop and demonstrate an innovative technology important to industry
and society, a systems engineering strategy has been chosen. Such an approach includes
analyses of customer needs, establishing technical and system requirements, concept
trade studies, benchmarking, and mathematical analysis. The PCUAV project was started
in July of 1998 and will end in June of 2000. The initial goal of the project is to develop
a prototype vehicle and to demonstrate important technologies necessary to the overall
concept.
1.2
UA Vs
The acronym UAV stands for "Unmanned Aerial Vehicle" or "Uninhabited Aerial
Vehicle," which refers to a vehicle that possesses different levels of autonomy. UAVs do
not have on-board human pilots. These aerial vehicles generally possess the following
characteristics:
*
unmanned operation
*
flight capabilities
*
data gathering capability
*
ability to deliver/transmit that data for analysis
In general, UAVs are not limited in size, shape, or performance characteristics.
They fly, sense and gather data, transmit this data where it is required, and operate with
some autonomy. Unmanned operations are duties performed without the direct use of a
human operator. Latest technologies have allowed UAVs to understand certain directives
and to perform them under various conditions. As presently configured, UAVs have
been able to perform various operations for extended periods of time under the guidance
of computer navigation. Using Global Positioning System (GPS), dead reckoning, radar,
and other navigation tools, UAVs can operate with various levels of autonomy. (Ref. 7)
These unmanned vehicles are currently being designed and built for a small yet
expanding branch of the military. Some UAVs are as large as a ten-meter wingspan
plane (e.g. Predator vehicle described below) or they can be as small as a model rocket.
The issues of reconnaissance and surveillance are very important to the military. When
obstacles or environments disrupt the line of sight, it is important for the military to see
what can not be seen. Such an objective needs to be carried out quickly and effectively,
and without risk of losing a soldier. This requirement makes data gathering one of the
primary objectives for UAVs. While there are many types of data to be gathered, one of
the simplest types of desired data are visual information. To be able to see what's on the
other side of a hill is very important before a soldier is to climb over that hill. There are
several sensors available for gathering vision-type data. Today's UAVs can sense
virtually anything using photography, sonar, radar, metal detectors, lasers etc.
While data gathering is important it is even more imperative to make use of such
information in a timely fashion. Vehicles must have a way to communicate the acquired
data to a place where it can be analyzed or else the mission would be a failure. Use of
video transmission and other telecommunication sensors are very important in the design
of such vehicles. In many instances, vehicles have a single chance to transmit their data.
Such communication can involve modem use, direct cable link, or even tele-transmission.
It is widely accepted that UAVs will become an integral part of the future for both
military and commercial missions. In 1997, the world market revenues for the military
component of this industry made up nearly $2 billion, while the civil market made up $80
million. Post-2000 growth acceleration has been predicted to be 10.4 % (military) and
11.8 % (civil). Experts believe that because such advances are crucial to world's interests
certain factors will drive the market. Further advances in payload miniaturization using
the Micro-mechanical Electro-Mechanical systems (MEMs) technology, communication
capabilities, system ruggedness, and introduction into civil environments will drive the
future market while present interim UAVs are being used to satisfy immediate
reconnaissance needs. Leaders in the market will be those with a mature and effective
vehicle that is prepared to work as a reliable data and imaging instrument. Once the full
breadth of vehicle technology is developed, the benefits of these types of vehicles would
become apparent and extremely valuable. Examples of UAVs included the operational
Predator vehicle, pre-operational Global Hawk, and the applied research Sender vehicle.
(Ref. 2)
1.2.1 PredatorUAV
Predator, a Medium Altitude Endurance (MAE) Unmanned Aerial Vehicle, seen in
Figure 1.2.1, is an operational asset in the USAF having transitioned out of the Advanced
Concept Technology Demonstration Program being managed by the Defense Airborne
Reconnaissance Office some time ago. Built by General Atomics, Predator has been
developed with a 20 million-dollar budget. The vehicle is similar to a small aircraft,
powered by a four-cylinder fuel-injected reciprocating engine driving a fixed-pitch
propeller and incorporates electro-optic, infrared, and synthetic aperture radar sensors.
Predator can fly at altitudes up to 25,000 ft., has a maximum endurance of 40 hours, and
a dash speed of 110 knots. It has a wingspan of 48 feet and a body length of 28 feet.
Imagery and air vehicle commands can be transmitted to and from the UAV either by CBand line-of-sight or one of two SATCOM data links (UHF or Ku-Band). This UAV is
designed to operate autonomously for extended periods (up to 24 hours on station) of
time. Predator taxis and launches conventionally from a semi-prepared surface under RF
control. (Ref. 4)
Figure1.2.1: PredatorUAV
Predator UAV systems are designed to provide long-range, long-dwell, near realtime data gathering intelligence to satisfy reconnaissance, surveillance and target
acquisition mission requirements. The system was first deployed in Bosnia in July 1995,
where it conducted almost daily reconnaissance operations in combat environments for
the U.S. and NATO forces. Such a system is slated for use in the future for many
military, governmental and commercial programs. It will allow the military to have
better detection of obscured targets, laser targeting, mine detection, and airborne early
warning. Other applications for this system could include border surveillance, countering
narcotics, environmental monitoring, meteorological monitoring/research, law
enforcement support, and disaster area surveys/assistance. Commercial projects could
range from surveying, mapping, and natural resource monitoring. (Ref. 4)
1.2.2
Global Hawk UAV
Global Hawk is a Tier II Plus High Altitude Endurance (HAE) UAV Program. A
high altitude, long endurance aerial reconnaissance system, it will provide military field
commanders with high-resolution, near real-time imagery of large geographic areas via
worldwide satellite communication links and the UAV's ground segment. Global Hawk,
as seen in Figure 1.2.2, is optimized for low-to-moderate threat reconnaissance missions
where range, endurance and persistent coverage are paramount. The vehicle with its 116foot wingspan and 44-foot length carries both synthetic aperture radar and electro-optical
/infrared sensors. (Ref. 5)
Figure1.2.2: GlobalHawk UA V
This standoff sustained high altitude surveillance and reconnaissance UAV is able
to survey, in one day, an area equivalent to the state of Illinois (40,000 square nautical
miles), while providing imagery with a three-foot resolution. Alternatively, the system
can provide more detailed (one-foot resolution) spot images if needed. For a typical
mission, as seen in Figure 1.2.3, Global Hawk can fly to a target area 3,000 nautical miles
away, and stay airborne for 24 hours collecting data before returning. It flies at altitudes
up to 65,000ft. It is capable of both wide-band satellite and line-of-sight data link
communications. Numerous air-worthiness evaluation and payload demonstration flights
are planned for this vehicle.
Figure 1.2.3: HAE Missions
Global Hawk is being developed within the two-vehicle High Altitude Endurance
UAV Program, managed by Defense Advanced Research Programs Agency for the
Defense Airborne Reconnaissance Office, with US Air Force, Navy and Army
participation. Cost is an important constraint. Contractors are required to meet a $10
million unit flyaway price for the average cost of air vehicles 11-20. They can trade off
all other system attributes, including performance, against this cost constraint.
With its advanced technology and range greater than half way around the world,
and the ability to remain on station at extremely high altitudes for prolonged periods of
time, Global Hawk has opened the door to the future. It is leading the way for a
battlefield commander to obtain vital intelligence information needed to achieve
information dominance throughout a given battle space well into the 21st century.
(Ref. 5)
1.2.3
Sender UAV
Naval Research Laboratory (NRL) has developed a stage 6.2 (Applied Research)
unmanned aerial vehicle called the Sender. The vehicle is sponsored by the Defense
Advanced Research Programs Agency (DARPA) fits the new requirement of UAVs
heading into the next century. Sender, presented in Figure 1.2.4, was designed to be an
electric drone having high endurance, long range, and yet small in size. It can be
transported by one soldier and packed in a suitcase can have a one-way range of 100
miles. While being four feet in wingspan and carrying a 2.5 lb. payload it has speeds in
the range of 50 to 90 knots as well as an endurance of two hours.
Figure1.2.4: Sender UAV
Sender is part of a broader UAV venture with DARPA, with funding of over $35
Million. Naval Research Laboratory (NRL) is in its 3rd year of its five-year program
with a funding of $7 Million. New demands by DARPA on UAV performance
characteristics have provided the impetus for such technology advances as seen in the
Sender design. (Ref. 6)
This vehicle was initially designed in a period of two months with three people.
Future technology advances with this vehicle would possibly include using fuel cells as a
replacement for batteries. Research goals have led the NRL to work with IGR enterprises
in the implementation and development of solid oxide fuel cells. Solid oxide fuel cells
are carbon-air based and DARPA funded. This system has problems with high thermal
generation, yet the goal is to use it to replace lithium batteries. These cells will decrease
weight (electric batteries approximately make up 30% of the Sender's weight), increase
power, and increase extraction rate. NRL has also internally developed an autopilot
system, staggering tails design, and a unique composite aerodynamic airframe. The new
type of airframe is a fiberglass, thin shell construction that weighs 1.5 to 2 lbs. Sender
was optimized in order to maximize flexibility. This was paramount because of the
changing nature of military spending and with increasing number of leaders calling for
the design of a vehicle which can perform numerous, diverse missions. NRL designed a
vehicle that would be capable of integrating various sensors and thus perform multiple
missions.
Manufacturing cost for the Sender is listed between $5K to $7K that does not
include the avionics. Its cost breakdown consists of motors ($500), airframe ($2K),
batteries ($500), avionics ($1 OK), and sensors ($2K). Sender has a total target price of
less than $20K. (Ref. 6)
Sender vehicles were considered seriously during the team's development and
analysis of an UAV. This unmanned aerial vehicle with new innovative features is a
benchmark for future work in the small UAV market. Table 1.2.1 shows how Sender
vehicles compare in the desired small UAV market categories.
1.3
Micro Aerial Vehicles
A combination of radically changed geopolitical environment and continuous
technological progress will have profound implications for the way that wars are fought
and for the kinds of forces and weapon systems that will dominate future battlefields. A
need for information in multiple forms and with redundancy is quite apparent. New
tactical operations such as close air support with long-range precision strikes (i.e. lasertargeted bombs) will create a need for very small (micro) UAVs to support the
surveillance needs of platoon level ground troops. Micro Aerial Vehicles (MAVs)
potentially could be extremely useful in reconnaissance and data gathering missions.
Table 1.2.1: Initial UAV Trade Study
They may also be useful for timely sensing of threats such as chemical/biological
agents, damage assessment, small weapons delivery, or observing an objective just prior
to mission execution. Such missions are staged in multiple, diverse environments
including desert, high foliage, sea, and urban. Many experts in the industry feel that
urban environments will be especially challenging. Other non-military needs such as
area surveillance to support non-combatant evacuation operations in foreign countries,
and drug interdiction have also become apparent. Various other commercial applications
have also been noted. By using MAVs, researchers could gain a tool in exploring areas
once unable to be explored. Civilian applications possibly could include fire fighting,
police assistance, border surveillance, etc. (Ref. 3)
The last twenty-five years have seen an enormous growth in the enabling
technologies that support development of autonomous vehicles. Capabilities in the
supporting technologies such as mission planning, navigation, sensing, compact
processing, and platform maneuverability have yielded a host of valuable assets with
aerial vehicles such as Darkstar, Exdrone, Global Hawk, Predator, Pointer and many
others that are smaller like the Flyrt, Dragon Drone etc. UAVs have proven to be highly
effective in certain support roles. Over the past three years, the Department of Defense
(DoD) has made use of UAVs for reconnaissance in Somalia, Haiti, and Bosnia. The
predator has received significant press in its military application during the Gulf war and
Bosnia operations. Given expected further advances in the sub-miniaturization (e.g.
MEMS), guided munitions such as ERGM, GPS, battery power, short takeoff and
landing, and changing concepts of operation the direction of UAVs is likely to be toward
smaller but still more capable systems. Smaller vehicles would include MAVs.
Technology advances must tackle two problems with micro vehicles: 1) Stability and
controllability of flight, 2) Endurance, and 3) Subsystem miniaturization.
The numerous studies, assessments, and reviews have distilled the needs for the
very small air vehicles to a few performance drivers. In order to be practically employed
in a diversity of missions and environments, from open terrain to dense urban canyons
and perhaps even to interior building operations, the DOD needs small back-packable air
vehicles that are very simple to operate and can perform some basic military missions
with a reasonable degree of autonomy. DARPA and Draper believe that MAVs should
have much lower costs than existing large vehicles and be designed for quick reaction i.e.
be quickly and easily set up and launched. Visual surveillance is clearly a fundamental
need. These vehicles' prime value is that they can potentially extend the eyes of their
users such that they can see things that are too dangerous or remote to be seen at very
close distances. Ultimately, the vehicle should be highly maneuverable, take off and land
autonomously, avoid obstacles, be operable by a single soldier, require little training to
operate, and inexpensive enough to be considered expendable. The vehicle might be no
bigger than six inches and sustain an autonomous surveillance mission for 60 minutes.
Desirable attributes should include low logistics and high reliability. There are numerous
military, quasi-military, and civilian applications that correspond to MAV use. These
include operations such as battle damage assessment, signal jamming, friendly signal
relay, obstacle tracking, and area grid generation. Although many different payloads
would be considered to support such missions, the most fundamental requirement is for
real-time vision. (Ref. 1)
Micro Aerial Vehicles or MAVs are being developed to provide a highly portable
and easy-to-use autonomous intelligence, surveillance, and reconnaissance capability for
small groups of land-based warfighters in tactical operations. A typical MAV System
consists of a MAV and a Ground Control Unit (GCU). There are numerous MAV
projects under development across the world. The United States agency DARPA is
presently considered to be the premier player in this industry. It is no secret therefore
that DARPA is setting the requirements for a fieldable MAV. On its wish list are
specifications that call for a micro vehicle with a wingspan of less than six inches and
which has high maneuverability and endurance. Draper in conjunction with Lutronix
Corporation is currently developing a rotary wing MAV, presented in Figure 1.3.1 along
with an assortment of other candidate MAVS. This Draper vehicle is a proof-of-concept
design and hovers like a helicopter. (Ref. 3)
Hovering MAV
stabilators
camera
internal structure
Figure 1.3.1 Micro Aerial Vehicles
1.4
Needfor a PCUA V vehicle
An autonomous vehicle serves the purpose of eliminating humans from hazardous
environments. Autonomous vehicles serve humans and provide them with a tool that can
be used to reduce harm and injury to society. For example, an UAV could be sent to fly
over a war zone guarded with anti-aircraft weaponry. Such an UAV could take important
pictures of the area and relay them to a command center miles away.
The tools used by the Explosive Ordinance Disposal (EOD) unit of the Marines is
another prime example of robots performing hazardous tasks. Marines have the
undesirable duty of walking over zones where cluster munitions have been dropped and
actually must pick them up and hand carry the unexploded bomblets to a disposal site.
Such a task involves serious risk to these soldiers' lives. To mitigate such risk, EOD has
contracted to create an autonomous ground rover that systematically searches an area,
detects ordinances, picks them up, and carries them to a disposal unit, thus such a system
eliminates humans from the inner and most dangerous loop. This is just an example of
hazardous activities that can be done better, safer, and cheaper with autonomous vehicles.
Biological systems such as flocks of birds, schools of fish, and colonies of ants,
termites, and bees, provide existence proofs that systems comprised of many elements
can exhibit interesting and useful behaviors. An attempt on similar lines is being made
by the MIT/DRAPER technology demonstration program to build a swarm of MAVs and
possibly miniature UAVs, deploy them from a mother-ship or a parent and coordinate
their activities to execute a given mission. For this project it is envisioned to take
advantage of the latest developments in technologies to mass-produce cheap MAVs that
may be disposed off at the end of a mission.
1.4.1 PotentialAdvantages
A Parent-Child Unmanned Aerial Vehicle (PCUAV) system has the following
potential advantages over other conventional UAV systems:
1. Higher reliability of overall mission execution.
2. Multiple missions can be executed taking advantage of the modular nature of the
Parent-Child (PC) system.
3. More efficient and faster search (for people, tanks, chemical/biological
substances) in a given area.
4. Simultaneous acquisition of spatial and temporal data over a given region.
6. Partially autonomous, requiring only an untrained pilot to supervise a mission.
7. Cost effective (using low cost, low weight systems).
Children UAVs are in effect the eyes and ears for the parent UAV but are smaller,
lower cost, and can act alone or together. They can fill in for each other if one is lost
providing redundancy to the integrated system. Because they have an ability to
communicate via links back to the parent, children can have lower power sources, as
opposed to having to link back home to the ground site requiring greater power output.
Key advantage of the PC system is that due to parent long range and endurance, the
children can be carried in from a long distance and deployed with extreme accuracy at a
desired drop site.
Multiple technology factors are also bound to enhance future PCUAV systems.
Such technologies include micro GPS (for MAVs), robust communication links, high
energy density and high power density energy sources, efficient propulsion designs,
potential recharging, refueling or rendezvous capability, wireless LAN integration etc.
Advances and subsequent integration into the PC concept will allow for future successes.
Designing to allow for such changes has been a driving force in the current PCUAV
system's design.
1.4.2 Applications
The PCUAV system has many potential applications. A few are listed below and
will be looked at in detail later.
Armed forces:
a) Surveillance - Bomb damage assessment, target geo-location
b) Signal Intelligence - Collection, smart jamming
c) Sensor Deployment.
d) Data Relay.
Environmental supervision:
a) Studying chemical effluents.
b) Wildlife and forest protection.
c) Exploration.
Hazard assistance in civilian environment:
a) Surveillance of buildings on fire.
b) Surveillance of collapsed structures.
Commercial applications:
a) Video exploration
Civilian monitoring:
a) Border patrol
b) Narcotics
c) Natural disaster assessments
d) Traffic
e) Coast Guard
Figure 1.4.1 depicts a possible PCUAV mission. In this scenario, a parent vehicle
of three to four meter wingspan travels to a distance of approximately 100 kilometers and
deploys its cargo. Its cargo includes two mini-vehicles of one-meter wingspan each and
potentially four micro-vehicles of six-inch size. These vehicles could include the MAVs
discussed earlier, unmanned ground vehicles, or other types of sensors. Such vehicles
would stick to a parent-child strategy where the mother vehicle supervises the children,
who perform the desired mission. Individual responsibilities and assets will be looked at
later. One of the core attributes of such a PCUAV system is its versatility. It can deploy
multiple types of vehicles in diverse environments. PCUAV has the ability to perform a
mission, which entails ground, low-altitude, and high altitude data gathering. Most other
UAVs are designed to target a singular mission.
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Figure 1.4.1: PCUA V - Potential Missions - Versatility
1.5
Thesis Objectives
This thesis details the layout for the design and development of a prototype UAV
(parent), which carries and cooperates with other smaller (children) vehicles. The
systems approach in choosing such a vehicle and the initial mechanical design of a
prototype is presented. This Parent-Child Unmanned Aerial Vehicle (PCUAV) design is
intended to prove the concept and demonstrate the potential technology "unobtainiums."
This work will allow for further research in the area leading to a finalized product. This
thesis will lay a documented foundation for future work in the parent-child unmanned
vehicle area.
CHAPTER 2
2.1
Problem Definition & Strategic Roles
Scope of the PCUA Vproject
PCUAV system has been projected to be operational by the year 2003, which
coincides with DARPA's targeted maturity date for other MAV systems. Because the
PCUAV system has utilized such emerging technologies, the MIT/Draper team has set
such a timeline. An immediate two-year timeline, as seen in Figure 2.1.1, lays the
foundation for the PCUAV team's design and development. (Ref. 24)
MIT/Draper Technology Dvmt. Partnership
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Figure2.1.1. Scope of the PCUAVproject
A system's engineering approach has been integrated into this two-year schedule,
with a belief that such a process would best optimize development of the new, innovative
concept. First step in this process was the determination of the customer needs.
2.2
Customer Needs
To establish what the potential customers for the PCUAV project wanted in an
aerial vehicle, which could transport micro aerial vehicles, a number of contacts and
industry meetings were arranged. These customer needs were weighted against
conceived system requirements, in order to develop a proper concept, which could be
marketed within the industry. Because no one had really tackled this issue or conceived
such a vehicle, this task was very difficult but very interesting. A number of needs for an
aerial vehicle had already been established based on vehicles such as the Sender (see
section 1.2). These requirements included developing a vehicle which would be two-man
portable on the back of a Humvee or small ship as well as being able to takeoff and land
in a short area (-20m). Other aspects of autonomy, such as autopilot integration and
potential vehicle emergency procedures, were also considered. While identifying
customer needs, it was also a goal to learn about potential UAV & MAV applications,
discuss new technologies and advancements, military and commercial operational
requirements, and establish contacts with potential future customers.
An important member of the UAV community, who conveys interest in the team's
project, is Dr. James McMichael. Dr. McMichael is the DARPA MAV program
manager. From a meeting with him, a number of customer needs were derived. Dr.
McMichael felt that the parent vehicle should be able to have a range of 100 nautical
miles, two ways. It should be able to loiter and relay for approximately two hours and
have a payload of three to four micro vehicles. He also felt that the parent need not be
fast unless the mission called for it but should be able to operate in 25 knots of wind gust.
Dr. McMichael also has strong interest in a number of possible scenarios for the system.
They include: targeting for artillery, signal jamming, and series deployment for
surveillance. He pointed out that because soldiers would be the largest markets for such
systems, the vehicle should be designed targeting that group. On a final note, he also had
some thoughts regarding possible sustainable missions where the parent could replenish
or rendezvous with its children to allow for longer missions. (Ref. 8)
In order to tackle the issue of making the PCUAV system flexible and versatile, the
team felt it was important to understand the need of other sectors in the UAV industry,
such as Unmanned Ground Vehicles (UGVs). UGVs could also be a potential candidate
for children deployed by the parent. To this effect, a meeting was arranged with Col.
John Blitch of the Army, the present DARPA UGV Project Manager. He felt that the
parent should be able to deploy different types of UGVs, yet the deployment did not need
to be very precise, as the children can be smart. By smart, the Colonel explained that
UGVs would be equipped with the Global Positioning Systems or GPS and potentially
other means for terrain mapping. He felt the minimum deployment range should be 40
km. An important issue he brought up regarded the weight of the system and its
assembly. He felt the system should be light and easy to assemble, as soldiers would
have to carry and operate these devices. On a final issue, he felt the cost of such a system
should not exceed $50K. (Ref. 9)
Other meetings were also arranged with the following UAV, military, and,
reconnaissance specialists: Rick Foch (Naval Research Lab, MAV director), Bob Parisien
(FBI Technology Department), Prof. Sheila Widnall (Ex-Secretary of Air Force), Matt
Keennon (Aerenvironment MAV engineer), Bill Harvey (UAV engineer), and Bob Davis
(MIT/Lincoln Lab MAV program manager). From these meetings, other customer
requirements were identified including the elimination of nets for landing, use of
common fuels, day/night capability, all weather operations, low cost of ownership, low
mission cycle time, low objective location error, interoperability, spectrum of data
collection, and portability. From these meetings, it also became clear that there was a
potential commercial as well as military use for the PCUAV system.
2.3
System Requirements
From the customer meetings listed in Section 2.2, each need was weighted in
regards to the agency they originated from. These weightings are presented in Table
2.3.1. From this table, a number of core technical approaches or system requirements
were derived to allow the PCUAV system to meet customer needs. The first requirement
was defined as Integrated Vehicle Design. Basically the team felt, as the PCUAV was
going to have multiple vehicle or children, that it would be advantageous to use the
children in helping the parent perform its goals. For example, if a PCUAV system were
chosen with miniature UAVs or minis under its wings, it would make sense to use the
mini's propulsion to aid the parent. Thus an integrated approach would help meet the
customer needs of endurance, range, short takeoff and landing etc.
Table 2.3.1 Structuring Customer Needs
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chosen in order to allow the vehicle to meet range and endurance requirements. Such a
requirement was compared to the Sender vehicle. From the industry meetings it was
evident that the sleek bullet-like design of Sender aided in its top-level performance.
Another requirement defined was multiple sensor data fusion and efficient data collection
and processing. This would allow the system to be versatile in collecting different types
of data and to perform multiple missions. Autonomous Guidance Navigation and Control
(GNC), expert mission planning, and night sensor capability were also identified in order
to meet ease of use, day/night operations, and optimization of mission time needs. Other
requirements include rugged/robust design, low specific fuel consumption, lightweight
structure, and child vehicle management and control.
2.4
Requirements Prioritization
To better understand the technical challenges, technical requirements were
prioritized and compared to the customer needs. Table 2.4.1 presents the QFD
requirement matrix developed by the team for the PCUAV project. Customer needs were
weighted using the matrix results presented in Table 2.3.1. The development of the QFD
matrix is very important as it lays a foundation for the design of the PCUAV system. It
will be used in verifying technical designs, approaches, missions, and performance
characteristics. (Ref. 26)
Table 2.4.1 Requirement Prioritization
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Figure 2.4.1 Top System Requirements for PCUAV
After having prioritized requirements, a number of different concepts were
developed, with a goal of down-selecting them against customer needs and the system
requirements.
CHAPTER 3
3.1
Vehicle Concept Study
Architecture Trade Study Process
Three feasible concepts were derived and developed by the team. Concepts were to
fit in the parent-child genre and possibly be valuable to potential customers. The first
concept derived was a fleet or flock of Sender-class UAVs, each of which could carry a
MAV as their payload. The flock would cooperate and act autonomously in performing
the desired mission.
A second concept was focused on the integrated design approach. This system
would be made up of a parent and two mini-vehicles. Each mini-vehicle would be
mounted on the external of the parent and assist in flight. At the required deployment
site, the minis would separate and cooperatively perform the mission with the parent.
Finally, a third concept conceived originated from the MAV deployment mission.
Four micro-pallets, which would house MAVs, UGVs, or other sensors, would be carried
in the parent fuselage. At the required deployment site the parent would drop the pallets
using a steerable parafoil system to the necessary zone. The parent would then act
cooperatively with the micro-vehicles and also relay information from the micro-vehicles
to the ground station unit. Current Micro Aerial Vehicle concepts are hampered by their
inability to transmit data from more than a one-kilometer range. Thus a loitering parent
could extend the range of useful MAV or UGV missions by acting as a relay station.
A trade study or matrix was performed, as presented in Table 3.1.1, comparing the
three concepts or architectures. Weightings were also assigned to each need to allow for
better fidelity results. As seen in the matrix, Architecture or Concept III scored the
highest marks but as it turned out all three concepts were closely ranked. This led to the
derivation of Architecture 401 presented below.
3.1.1
Architecture 401:The PreferredSystem Concept
Architecture 401, the preferred system concept, is a stand-alone system, which
deploys minis, MAVs, UGVs, & sensors in hazardous environments. Two minis would
be integrated into the parent design and aid in the parent mission. This concept also
offers a potential relay communication between vehicles extending range between the
MAV to mini to parent. At present MAVs can only transmit within 1 km. Each mini
potentially can relay the MAVs transmission to the parent. The parent who can transmit
and receive information from greater than 100 km will be the key link in this architecture.
Building on Concept I above, the PCUAV can also be integrated with a HAE (High
Altitude Endurance) UAV (i.e. Global Hawk) to allow for longer endurance, SATCOM,
and redundancy. Potentially a number of PCUAVs could be deployed from the Global
Hawk and work as a flock of birds. This architecture will also allow for retrieval and
refueling of the children by the parent. Because the minis assist in parent propulsion,
such a refueling network will be closely coupled with the mechanical separation design.
This system will also be two-man portable with the capability to perform short takeoff
and landing. Approaches for this will be discussed in later sections but the techniques for
accomplishing this include a parafoil landing and bungee-rail launch.
Table 3.1.1 Trade Matrix Derivation of the Concept
Characteristic
M ultimission
Unobtainium
Reu s ability
Gather Info/Payload Cap
Reliability (Mission Execution)
Short T/O and Landing
Portability
Feasibility
Covert/Stealth
A 11W eather
Cost
Maintenance (Refuel-charge)
Weighting
Arch I
Arch II
Arch m
Arch I'
Arch II'
Arch II'
10
10
8
8
8
3
3
5
3
5
4
4
3
4
3
5
5
4
5
2
30
30
40
24
40
40
40
24
32
24
50
50
32
40
16
8
7
5
5
4
4
3
3
2
5
2
5
1
4
4
4
4
3
4
2
4
3
4
3
5
3
3
4
24
14
25
10
20
4
12
32
28
20
15
16
8
12
24
28
15
25
12
12
12
273
291
SMAX
400
The chosen PCUAV system has a number of technical challenges. This complex
three-level architecture is an integrated UAV concept not found in either production or
proposal. Technical challenges include: high performance, integrated multi-vehicle
configuration, mission planning for multiple aircraft, parent mini-micro TD&C
316
communication and onboard data multiplexing, parent-mini-micro TD&C
communication links, and ground station command of a n-vehicle system.
Other challenges include the avionics design for the parent UAV, deployment, and
precision delivery of the MAVs, deployment of the mini UAV, and the integrated fuel
system. Potential benefits are associated with a system-of-systems concept, such as
swarms of bees, school of fish etc. Advancement in micro-mini UAVs, sensors, ground
rovers are also needed for the advancement of the PCUAV. DARPA has design
development experience with a cross-section of vehicle types, launch vehicles, ground
rovers, submersibles, rotorcraft, projectiles etc. The key to the PCUAV will be the
communication, control, and autonomous cooperation with the children. Because the
system is flexible to perform multiple missions and there is high redundancy and
therefore higher reliability of mission execution, the team felt that Architecture 401 was
the best choice.
3.2
PCUA V meets Requirements
To verify the choice of the PCUAV concept, the system was analyzed with respect
to the prioritized system requirements and customer needs. Table 3.2.1 is the product
attribute QFD matrix, comparing product attributes and technical requirements. In the
QFD it is evident that the PCUAV architecture derived from the down select meets many
of the technical requirements established in the QFD requirement matrix. The attributes
noted for the system were conceived in formulating architecture 401. These attributes
will be discussed in later sections.
3.2.1
Three-Tier System
The Parent-Child Unmanned Aerial Vehicle was initially sized in order to meet
cargo, payload, and sub-component capacity. The vehicle is designed to be
approximately 3.4-meter wingspan and weigh 10 to 15 kg. It is to have a range of 100
km (two-way) and an endurance of 2.5 to 4 hrs. Its payload includes two mini-vehicles
and four six inch pallets (devices that hold UGV or MAV). The mini-vehicle was
initially scaled at one-meter wingspan and weigh five kg. It has a possible payload of
deployable sensors. Figure 3.2.1 depicts the PCUAV system and its classes. The
derivation of the sizes for the parent vehicle was a function of internal
payload/component space, endurance, altitude, weight, and wing loading.
Table 3.2.1 ProductAttribute QFD Matrix
M-
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Efficient Aero/Control Design
MultipleSensorDataFusion
Autonomnous
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Top
Stable Platform
Technicat
E VpertMissionPlanning
Requrements Rugged/RobustDesign
Night Sensor Capability
Efficient Data Collect &Process
Low Specific Fuel Consumption
Light Weight Structure
ChildVehicle Mangmt &Control
______Total Ratings
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Parent
Mini
4,
g
'
MAV
I-
UGV
4-- Sensor
Figure3.2.1 PCUA V classes
Classification of the PCUAV system is very interesting. There is no precedent for
this class of unmanned aerial vehicle. While the parent is in a class similar to other three
to five meter UAVs like the Exdrone it is designed for longer endurance. Scope of the
PCUAV system, as seen in Figure 3.2.2, is one, which encompasses multiple classes or
tiers of UAVs. The three main tiers include the tactical, close range, and micro UAVs,
thus generating the three-tier unmanned aerial vehicle. There also is a possibility for a
fourth tier, which includes the High Altitude Endurance and Medium Altitude Endurance
unmanned aerial vehicles. Thus the PCUAV system could potentially be deployed like a
child from its parent vehicle such as Global Hawk.
As the Figure 3.2.2 notes no other single system compares to PCUAV. By creating
the fourth tier and integrating a HAE UAV into the PCUAV system it will potentially
allow for pin-point deployment of sensors, MAVs, & UGVs from thousands of miles
away. (Ref. 16)
UAV
Wingspan
(m)
HAE UAV
Global Hawk *
Darkstar
20-
MAE UAV
Predator
PCUAV "SCOPE"
1
100
1000
Very Far
Two-way Range (km)
Figure 3.2.2 PCUA V Scope
Complementing the development of the PCUAV by the team, a vehicle database
was compiled listing all classes, subclasses, and performance specifications of
operational and developmental UAVs. Figure 3.2.3. shows where the PCUAV could
potentially fit in the UAV classes relative to size.
&
Figure 3.2.3. PCUA V Class by Size
PCUAV system fits it with fixed wing UAVs, similar to the Exdrone, Sender, and
Dragon. (Ref. 16)
3.2.2
Strategic Missions
Versatility is very important to the potential customers of PCUAV. To have a
single system which can perform multiple missions reliably is extremely valuable,
especially in the defense industry.
3.2.3
Potential Users
A number of potential users have been identified for the three-tier system. These
users are listed in Figure 3.2.4.
3.3
PCUAV Mission Scenarios
In this section, PCUAV missions will be dissected and analyzed so that the
advantages of the system can be better identified. Every scenario is a composition of
primitive "building blocks." The six main functional primitives of the PCUAV mission
are:
1. Launch & Recovery
2. Point-to-Point Navigation
3. Target Identification & Acquisition
4. Target Tracking
5. Payload Operations
6. User Command Response
,------------------------PCUAV
-
users
Army
Navy
Special Forces
FBI/Police
Border Patrol
Presidential
News and Media
Exploration
Traffic Managm
Emergency/Crisis
Hazard Assistanc
ire Departmen
Figure3.2.4 PotentialUsers
Launch and recovery is very important to the PCUAV system as there is a customer
need for the system to be easy to use and be able to takeoff and land is a small area (-20
m radius). A number of factors related to launch and recovery must be looked at
including:
*
simplicity of pre-flight preparation (assembly, checkout),
*
turn-around time (refueling, payload servicing, etc),
*
minimal support hardware/personnel,
*
simplicity of launch procedures,
*
flexibility of location/conditions,
* prepared/unprepared surfaces,
*
ship fantails,
*
in-flight,
* ground vehicle,
* varying weather, and
* day or night
The whole concept of an aero vehicle to be rocket launchable imposes many
problems: a) stabilized flight during boost; b) tailoff and rocket motor ejection; c)
transition from ballistic to aerodynamic controls; and d) safety of subsystems during
setup and prelaunch ops.
Figure 3.3.1 depicts potential Take-Off (T/O) options. This system will be able to
be packaged in the back of a military Humvee truck or in a small area in the stern of a
military ship. Two men should be able to unpack the system and to mount the vehicle on
the bungee rail. The system must achieve a balance between simplicity and automation.
It would be desirable that the operators simply had to mount the vehicle. Then a simple
lever would eject the vehicle. Other factors, which must be considered, include the effect
of wind shear on the PCUAV wings when the vehicle is initially launched. If the force is
too high for the structural integrity of the vehicle the wings could possibly be ripped off.
PCUAV
HAE UAV
PCUAV
PCUAV
Land/Truck Launch*
NAVY ship Launch*
HAE UAV deployed
Figure 3.3.1 PotentialT/O Missions
A typical deployment scenario for the PCUAV is presented in Figure 3.3.2.
PCUAV system has the ability to strategically deploy children at 100 km away from the
ground station. Using a parafoil guided deployment mechanism a MAV, UGV or sensor
could potentially be delivered in a window, at a drop zone, or even at the foot of an
under-ground military facility.
Figure 3.3.2 Potential Deployment Missions
An ability to collect multiple types of data is a key part to the PCUAV system, as
depicted is Figure 3.3.3. The parent will have the capability to perform video
surveillance while the mini-vehicle will also have video surveillance, potentially
chemical and biological sensors, weather reading sensors, and radar jamming equipment.
MAVs will potentially have video and mine detection capabilities. Because MAV
technology is advancing quickly this area is still to be determined.
As noted earlier, the parent adds value to its children by extending their
transmission range. Figure 3.3.4 depicts a typical scenario where the micro vehicles are
at or one km above ground level. The mini-vehicles are loitering at a two-km altitude
with the parent at a strategic altitude of around five-km. Each mini-vehicle can also
potentially act as a redundant backup to the parent or visa versa, if either were to fail.
Basically if the mini-vehicle were to fail, the parent would fly to a lower altitude and
perform the mini-vehicle's mission.
Figure 3.3.3 Multiple Data Collection
-5 km
P,
-2km
VCU
T
-1km
100 km
Under Ground Facility
Figure 3.3.4 Potential Missions - Data Relay
Parent-Child Unmanned Aerial Vehicle has the ability to perform a number of
diverse missions due to its ability to hold interchangeable cargo pallets in its fuselage as
well as have two mini-vehicles as its children. As seen in Figure 3.3.5, the PCUAV can
fly to multiple deployment zones and perform multiple types of data collection. Imagine
a Global Hawk being deployed from an airstrip at a friendly base. The HAE UAV is
carrying two PCUAVs. These PCUAVs are equipped with two maneuverable minivehicles each carrying video, biological, and chemical sensors. Within the parent
fuselage are a MAV (hovering with radar jamming transmitter), a UGV (carrying video
and mine detection sensors), a MAV (fixed wing with detailed video sensors), and a
number of miniature sensors (auditory sensors or small beacons used for terrain
mapping). With this concept, the PCUAV can perform a number of missions.
Figure 3.3.5 Potential Missions - Versatility
One such mission is signal jamming. Because MAVs can fly close to enemy assets
without being detected, besides collecting data they may also be able to act offensively.
By placing small one-watt signal jamming transmitters in hovering or fixed wing MAVs,
the PCUAV can disrupt enemy radar. MAVs could potentially stick onto the enemy's
radar dish and wait there.
Another mission involves terrain mapping. A PCUAV can drop mapping sensors
over most drop zones. Suppose these sensors were designed similar to micro-sonar
buoys. The parent, via its pallet system, could drop these sensors at a pinpoint area, in
order to detect enemy submarines thereby mapping an under water grid.
Because MAVs can get extremely close to enemy targets they can perform bomb
damage assessment. By getting into missile craters, bombed buildings, doorways etc. and
ascertaining different views by different micros, the PCUAV can attain valuable
reconnaissance data.
The minis, which hover at a two-km altitude, have the ability to relay data as well
as perform missions that require high maneuverability and speed. Such missions include
following a train or a cargo vehicle in close pursuit. Each mini could also potentially
activate, deactivate, or recharge dropped sensors in order to maximize mission time.
Recharging of sensors was studied using microwave transmissions to recharge batteries.
Such research is very preliminary but potentially could be extremely valuable to the
PCUAV project.
The three-tier system has three classes of vehicles with different sizes. Such a class
system allows the system as a whole to have high flexibility without being in harms way.
A parent that is 3.4 meters in wingspan is in greater danger at low altitudes than a six
inch MAV. This is due to enemy radar sensitivity. It is very feasibly for a three to seven
meter wingspan reconnaissance drones to be easily shot down in hostile territory at low
altitudes. The parent may be in danger at altitudes of 500 meters to one kilometer. While
one meter minis and six-inch MAVs may be undetectable at extremely low altitudes such
as ten meters to ten feet. MAVs are also on the order of ten to fifteen times less in cost
than the parent and it contributes to the added advantage of having multiple classes.
Figure 3.3.6 shows the benefits that the PCUAV tier system allows regarding safety,
expendability, flight, and zone coverage.
A number of assumptions were made in the derivation of such thinking. Basically,
as size of an UAV increases, it is assumed to be safer farther from the ground where there
is the greatest threat. The ground, which is home to enemy surface-to-air weaponry, can
target a vehicle of 3.4 meters wingspan pretty easily if it can be seen. This is due to the
ease in detectability of the vehicle by enemy sensors, thus causing the vehicle to be more
vulnerable to hostile actions. Due to the existence of the minis, the tier system allows the
bigger parent to loiter at high altitudes away from potential harm's way.
The base PCUAV system is not a vertical take-off and landing system. But through
a number of concept studies, including looking at rocket assisted landing, airbag
deployment, skid landing, and runway landing, an approach was chosen which could
meet the recommended requirement of landing in a less than twenty-meter area.
Figure 3.3.6 Potential Missions - Harms Way
This generated approach, as seen in Figure 3.3.7, involves the use of GPS and a
controllable parafoil system. The parafoil system shown, which will be packed and
deployed from the parent fuselage can also be used with the minis. Using GPS and lasers
a number of off-the-shelf hardware systems are available for such an application.
GPS-laserbased
parafoillandingsystem
PCUAV
----
~
NAVY ship Landing
* Can be usedfor land-basedmissions
Figure3.3.7 PotentialMission - Landing
A parafoil system supplies a number of characteristics to the PCUAV concept. The
system: 1) aids in recovery, 2) allows precise landing in a 20 meter radius, 3) eliminates
use of nets, 4) is tested and proven to work (multiple video tests available), and 5) may
require a human supervisor.
Riegel Company has developed a GPS based parafoil landing system called the
LD90-31K GN&C system. System allows for an accurate real time distance
measurement from the vehicle (UAV) to the ground, in order to plan course, trajectory &
parafoil landing maneuvers. It has a range of 1500 meters and an accuracy of 0.5 meters.
Weight of the package is approximately 1.5 kilograms. Its size is 200mm long x 130mm
wide x 76 mm high, which potentially can be incorporated in the parent vehicle's
fuselage. Control of the parafoil could be coupled with the parent wing flap actuators and
the GPS guidance system with the parent avionics. (Ref. 17)
3.4
Competitors
The PCUAV system is a novel idea to the UAV industry. But the team has
assessed a number of potential competitors. A main competitor seems to be the small
Sender-class UAVs. This new type of UAV technology exhibits high performance
similar to the tactical range UAVs yet is much smaller. A flock of these UAVs could
potentially perform a number of the PCUAV missions. Competition must be studied
further through meetings with potential military users.
3.5
MechanicalDesign Considerationsand Constraints
The system concept of the PCUAV system leads to a number of technical
challenges as mentioned earlier. There are a number of major mechanical interface and
layout issues involved with this vehicle. One of the main system goals is to integrate
mini-vehicles into the parent design and propulsion. This involves mechanical
attachment and release points as well as potentially an integrated fuel and power system.
Integrated system would pass fuel and power to the mini-vehicles from the parent until
the minis are released. Such integration will also affect the minis, regarding having a
propeller in the front or back as well as possibly forming an airfoil/wing, which can be
embedded in the parent wing.
A detailed pallet deployment mechanism also must be designed for the PCUAV.
This will affect the sub-component layout of the parent as well as the fuselage structure
and robustness. The pallets could be deployed from the top, bottom, one at a time, or all
at once. Such a deployment could be performed with an ejection mechanism or passively
with cargo doors.
Finally everything must be packed into or on the parent structure. Internal layouts
must be optimized for potential parents. Parent vehicles may be either fixed wing, all
wing, delta wing, or boom configurations. These configurations must be compared by
payload capacity, endurance, maneuverability, speed, loiter ability etc. The vehicle also
must be two-man portable thus size is a major constraint.
CHAPTER 4
4.1
Vehicle Preliminary Design
System Outline
During the preliminary design phase of a parent vehicle the constraints listed above
need to be considered. A number of possible parents were studied and designed. Vehicle
types ranged from a fixed-wing to an all-wing vehicle configuration. Another design
constraint was to keep as many potential options open as possible for future flexibility in
the integration process. For example, one type of fixed wing design was unsuitable for
integrated design. In this example the mini-vehicle's propulsor was acting entirely as a
drag force and not assisting the parent. But such a vehicle configuration was not
eliminated as it allowed for easier rendezvous and other important desirable
characteristics. The goal of this vehicle study was to find a number of potential parentmini combinations which could best meet the requirements generated by the team.
4.2
Vehicle Geometry
Vehicle geometric configurations, which will be shown in a later section, were
developed by the team in an effort to optimize performance characteristics of the parent.
4.2.1
Parent Vehicle Configuration
An initial pre-prototype design of the parent vehicle, as presented in Figure 4.2.1,
has a wingspan of 3.40 meters and a fuselage length of 3.40 meters. The aspect ratio
chosen for the wing is 5, given a chord length of 0.68 meters. Wing planform area is
calculated to be 2.31 m2. This Figure was drawn through the use of the ProEngineer
design tool which is useful for designing complex three dimensional vehicles. Fuselage
width was designed to allow for a diameter of 0.34 meters. Such a dimension was chosen
to allow for the internal packaging of the sub-components, which include the micro
pallets themselves.
A first-order feasibility of this preliminary design vehicle layout can be derived
through computations of lift and drag forces and then balancing them against weight and
.68 m
D .34 m
.58 m
.68 m
3.4 m
3.4 m
Figure 4.2.1. Initial Parent Structure Layout
thrust available. This parent can have an approximate weight of 12 kg. Lift on the parent
vehicle can be computed by:
Lift =
1
p CSV 2
(1)
where p is the mass density (1.228 kg/mA3), C1 is the lift coefficient, S is the planform
area of the wing (neglecting other lifting surfaces) and V is the parent velocity. For a
velocity of 15 m/s lift is computed as presented in Figure 4.2.2. For a weight of 12 kg
(118 Newtons), lift coefficient required to fly the parent is 0.37. This value of lift
coefficient is a reasonably attainable number.
Similar to the lift force drag force on the parent vehicle can be computed by:
Drag=
p Cd(WSA)V 2
(2)
Here Cd is the drag coefficient and WSA is the wetted surface area of the parent
vehicle. A first order estimate of the parent-vehicle drag coefficient can be made as
follows:
* The skin-friction drag coefficient of a vehicle is a function of its relevant Reynold's
number given as:
R = VLk/
(3)
where V is the velocity, L is the characteristic length and v (1.45e-5 m^2/s) is the
kinematic viscosity of the fluid.
Lift Force versus Lift Coefficient
400
350
300
250
200
150 -
50
0
0.2
0.4
0.6
0.8
1
1.2
Lift coefficient
Figure 4.2.2 - Lift Force on Parent Vehicle
* The characteristic length for the parent was approximated to be 3.40 meters. A
velocity of 15.0 m/s gives a Reynold's number of 3.52e+6.
* Reference 10 gives several equations for computing skin-friction drag coefficients as
a function of Reynold's number. Three distinct equations valid for smooth and plane
surfaces in incompressible flow are plotted in Figure 4.2.3. The laminar boundary
layer curve is as given by equation 5.6.10 in Reference 10. This curve is valid up to
Reynold's numbers equal to 5 X 105. The transient equation is given by equation
5.6.18 in Reference 10 that is valid between Reynold's numbers equal to 5 X 105 and
107. The turbulent boundary layer equation valid for Reynold's numbers greater than
107, known as the Schoenherr equation (Ref. 11) is plotted as squares in Figure 4.2.3.
An approximation (Ref. 11) to the Schoenherr equation is written as equation (4)
below.
V1/-C = 3.46 log (R,)-5.6
(4)
where Cf is the skin-friction coefficient and R1 is the relevant (length) Reynold's
number. This equation, valid for turbulent flow, can be extended into the transition
and the laminar region if forced turbulence is assumed.
Skin-Friction Coefficient
0.01000
0.00100
1.00E+05
1.00E+06
1.00E+07
Length Reynold's No.
-
Schoenherr approx. --a- Schoenherr -
Laminar -
Transient
Figure4.2.3 - Skin Friction Coefficients
* The skin-friction coefficient computed from equation (4) is 0.0034.
* The form factors for a wing-shaped body are a function of thickness to chord ratios.
Assuming 40% increase in drag coefficient due to form-factor effects, Cd is estimated
to be 0.0048.
* WSA can be estimated from the wing and fuselage surface areas. Starting from the
wing planform area and multiplying by 2.2 (2 sides and 10% increase due to
thickness of wing) and then adding the surface area of a cylinder that has the diameter
equal to the maximum diameter of the fuselage and a length equal to 3 meters would
give a conservative value for the total wetted surface area. This value was computed
to be 8.29 m2 .
* Drag force is now computed using equation (2) to be 5.51 Newtons which for 15 m/s
velocity translates to 82.71 watts of power. Additional drag due to appendages could
increase the power required.
* As a comparison a 0.2 horsepower engine with an efficiency of 0.7 would provide
104.44 watts of power.
4.2.2 ParentVehicle Internal Component Packaging
Internal packaging of the parent must be considered for all designs of the parent.
The parent has requirements to hold a number of sub-components in its fuselage and
wings. These initial components with estimated dimensions include:
1.
Engine:
99mm L X 70mm W
2.
PC104:
90mm L X 96mm W X 15mm H
3.
Camera:
47mm L X 22mm D
4.
GPS:
179mm X 100mm X 18mm
5.
GPS Attenna:
114mm D X 100mm thickness
6.
IMU:
75mm X 75mm X 80mm
7.
PCMCIA:
90mm X 54mm X 5mm
8.
Transmitter:
165mm X 100mm X 20mm
9.
Cargo Pallets:
200mm X 200mm X 200mm
10.
Fuel Tank (6):
100mm X 100mm X 100mm
11.
Batteries:
100mm X 50 mm X 50mm
These dimensions were fed into the ProEngineer tool to obtain Figure 4.2.4, which
illustrates how these components were packaged in the parent fuselage. (Ref. 17)
4.2.3
Mini-Vehicle Configuration
The mini-vehicle has a wingspan of one meter and a fuselage length of one meter.
The aspect ratio chosen for the wing is five, given a chord length of 0.20 meters. Wing
planform area is calculated to be 0.20 m2 . Fuselage width was designed to allow for a
diameter of 0.15 meters. A mini would weigh approximately 1.2 Kg. Similar to the
parent vehicle, for a velocity of 15 m/s lift is computed as presented in Figure 4.2.5.
foil Batteries
amera
Engine
U
Parafoil
Fuel
GPS/Attenna
Figure 4.2.4 Parent Vehicle Internal Component Packaging
Lift Force versus Lift Coefficient
40
30
20
10
0
0
0.2
0.4
0.6
0.8
Lift coefficient
Figure 4.2.5 - Lift Force on the Mini-Vehicle
1
1.2
For a weight of 1.2 Kg (11.8 Newtons), the lift coefficient required to fly the parent
is 0.43. This value of lift coefficient is a reasonably attainable number. For the drag
force computations Reynold's number is 1.04e+6, Cf is 0.0043, and Cf with 40% increase
due to form-factor is 0.0061. The value for WSA is 0.82 m 2 that includes a 0.8-m long,
0.15-m dia cylindrical surface allowance for the fuselage. Drag force is now computed
using equation (2) to be 0.68 Newtons which for 15 m/s velocity translates to 10.24 watts
of power. Additional drag due to appendages could increase the power required. As a
comparison a 0.04 horsepower engine with an efficiency of 0.7 would provide 20.89
watts of power
4.3
IntegratedDesign
A number of factors are important in the integrated design of the parent and its
component mini-vehicles. Mini-vehicles must be mounted to the parent in a certain
manner to obtain stability in flight of the integrated system. This mounting is very
important, as it potentially will dramatically affect the aerodynamics of the system. In
some designs the mini-vehicle can also be embedded in the parent wing or the airfoil.
The mini could also be above the fuselage, at the wind tips, or under the wing. Design of
the mini itself also comes to play in this integration. A fixed wing mini potentially will
have a different integration then an all-wing mini. Figure 4.3.1 depicts a fixed wing mini
with a one-meter wingspan and a one-meter fuselage length (propeller in the front).
(Ref. 23)
Figure 4.3.1 Fixed Wing Mini
Figure 4.3.2 depicts an all-wing mini with a wingspan of 1.20 meters and overall
length of approximately 0.40 meters (propeller in the back). An aspect of the integration,
which is paramount to system success, is rendezvous or the process of retrieving the
10
12
a. C.
120
Note 1
chord at root
i
40
mean aerodynamic chord
1 28
wing area 1 0.3 sq, Meter
AR : 4.8
Figure 4.3.2 All Wing Mini (dimensions in cm)
children by the parent for the purposes of refueling or recharging them. Because
potential of rendezvous and refueling is a desired characteristic of the system, the
integration must be one that can be repetitive. Basically the minis should be able to redock with the parent and thus re-integrate. Interaction of two flying-vehicles in
proximity operations is a complex aerodynamic phenomenon that needs to be studied
very carefully. Computational fluid dynamics (CFD) codes could be used to study these
interaction forces and moments.
Initial integration layout of these minis is seen in Figure 4.3.3 and Figure 4.3.4
respectively. For the fixed-wing mini, the parent holds the mini under its wings.
Because mini's propeller is in front, its propeller adds forward thrust based at the front of
the parent wings. Each mini potentially will be embedded in the airfoil of the parent
wing.
Lift and drag of this configuration should be studied for its ability to sustain flight.
The combined weight of the system is 13.2 Kg or 129.49 Newtons. If it is assumed the
lift to be generated only by the parent wings (Figure 4.2.2), there will be a need for a lift
coefficient of 0.41 which is not much greater than the parent-alone value of 0.37.
Assuming the drag adds (a conservative value as some surfaces are overlapping), total
drag would be 6.20 Newtons that relates to 92.94 watts of power at 15.0 m/sec velocity.
Again a 0.2 horsepower engine (rI = 0.7) would generate 104.44 watts of power.
Mini
Parent
Figure 4.3.3 Parent-Mini Integration (both fixed wing)
For the all-wing mini (Figure 4.3.4), the propeller is in the back; thus the
attachment must be in the rear of the vehicle. By attaching the mini at the wing tips of
the parent, the PCUAV system will have increased its wingspan, which has potential
benefits in terms of lift generation while attached. The propeller in this case also adds a
pushing thrust to the parent.
Mini
Parent
Figure 4.3.4 Parent-Mini Integration (both all-wing)
The above integration concepts were conceived and developed by the team. Figure
4.3.5 shows some developed integration concepts. While other potential methods to
achieve integration exist, these were considered the most viable.
2
n
*fl4~
3
~r~4
K--LI
Lp ~
~Gct~1~a
=-f~"==4
~
t~L~
a-~~A
7o
Figure 4.3.5 Integration Concepts
Each of the twelve concept depicted above has unique positive and negative
attributes and further trade studies and refinement would be necessary to select an
optimum concept for a unique mission or class of missions. (Ref. 23)
CHAPTER 5
5.1
Parent-Child Integration Design
Mini Deployment
Deployment or launch of the mini-vehicle from the parent vehicle is a difficult
problem, as potentially the parent will also need to retrieve the mini at the same point.
Requirements for such a launch and docking procedure include:
1)
Transfer fuel, power, and electric signal before deployment.
2)
Deploy mini safely away from parent structure.
3)
Retrieve and re-dock mini in a reasonable amount of time.
4)
Have some autonomy.
5)
Safely re-dock mini with parent.
6)
Re-establish fuel, power, electric signal transfer.
7)
Have no leaks or faulty connections.
8)
Prevent entanglements, propeller hazards etc.
9)
Avoid structural detachment or failure from the complex two-body
dynamics.
To meet these initial mini deployment requirements an integrated fuel/separation
system has been initially designed.
5.2
Integrated Fuel/Separation System
The team felt that integration will serve a number of customer needs such as: 1)
ease of use, 2) all weather operations, 3) long endurance, 4) low mission cycle time, and
5) spectrum of collection capabilities. The design of this system will be very challenging.
During cruise out, the mini will be pulling/pushing, vibrating, and under different
bending load conditions than those of the parent. During this time, once again fuel
cannot leak. Upon mini-parent separation, the mini must be operating with its own fuel
and connection must be severed with no residual leaking. The challenge in the design is
coupled with the fact that there may be no precedent for an interface-system like this.
Integrated fuel/separation system was also designed to allow for ultimate retrieval
or rendezvous. The system depicted in Figure 5.2.1 and Figure 5.2.2 uses one-way fuel
Figure 5.2.1 Parent-Mini Separation System (side view - dimensions in cm)
Figure 5.2.2
Parent-Mini Separation System (front view - dimensions in cm)
nozzles, clamps, a retractable pulley system, and precision contact points. A detailed
description of the Parent-Mini separation system is presented in Figure 5.2.3.
System functional flow consists of the following steps:
1) Fuel/Electrical transfer via one way fuel nozzle system and electric contact points.
2) Mini-vehicle is supported by clamping mechanism and a pulling mechanism
(rendezvous system).
3) After mini-vehicle is released, pulley tension is released, clamp is opened, parent
fuel door is closed, and fuel/electric transfer is ceased.
Figure 5.2.3 Detailed Parent-Mini Separation System
Separation of the system must be performed reliably, under high tension, direst and
unstable conditions, and without fuel leaks. The system must also be easily setup
(parent-mini mounting) by the operator.
The fuel system, which is represented in the above Figure by an one-way nozzle on
the mini-vehicle and the fluid plumbing on the parent, can be better seen in Figure 5.2.4.
Fuel pumps on both minis created the necessary pressure difference to allow for fuel
transfer. One-way nozzles on both minis prevent leakage after separation. Parent fuel
doors, which close as the parent clamp is opened (release mini) and open as the parent
clamp is closed (hold mini) prevent leakage in the wings. As seen earlier, Figure 5.2.2
depicts how the fuel-line door is coupled with the clamp. One-way nozzles on the mini
are triangular in shape to both prevent leak and jamming caused by high moments on the
separation interface.
t--- - -- - - - -- - - - -- - - -- - - - -
Enginemini
I
m i
1....... __
p........mp
Engineparent
Door
One way fuel nozzles
Doo
r----------------------------------------
pump
Enginemini
. ... . . . . . . . . . .. . . . . . . . . . . .
Figure 5.2.4 Fuel system
Because the mini potentially could be embedded under the parent wing or within its
airfoil, the separation system has been initially designed for such an application. Figure
5.2.5 shows how the system can be altered to such a configuration, if desired. The
embedded mini adds to the efficiency of the PCUAV system as there is extra propulsion
but limited exposed wetted surface area for drag. After the mini is deployed the airfoil,
with the remaining hollow region, is designed to remain efficient. The penalties assumed
in this design are being considered and further researched. Integration is being
considered for aerodynamic efficiency, structural integrity or weight reduction, high-lift
integration concepts, controls, payload separation etc. An initial attempt at calculating a
preferred airfoil design led to a chord/length ratio of approximately five. (Ref. 25)
In the design of the separation system, the first-order computation of forces (lift,
drag, weight, suction around airfoil) and moments acting at the points of attachment are
necessary to weigh the feasibility of the approach. This is a major constraint on the
design of the attachment for the minis. The free-body diagram, presented in Figure 5.2.6,
allows for the moment of a simple attachment approach.
Internal
Structure
Parent wing
(sidp vipuw
\UU KVl
Parent wing
Parent wing
(bottom view)
Figure5.2.5 Embedded Approach (cross section views of parentwing)
Flift
Fdrag
Fweight
Figure5.2.6 Parent-MiniFree Body Diagram
As computed in Section 4.3 the combined weight of the system is 13.2 Kg or
129.49 Newtons. The lift force has to equal that value for equilibrium. For a 15 m/sec
flight, the drag and thrust of this system equals 6.2 Newtons. The moment on the
attachment point would be the lift force multiplied by the moment arm, which would be
on the order of 0.25 m given a moment of around 1.55 N-m.
5.3
Rendezvous
Development of a rendezvous system to retrieve children vehicles (Minis) by the
parent allows for sustainable, lower cost missions. Initial designs presented here for this
system are greatly influenced by the C-130 and flying boom aircraft refueling process. In
both systems, an aircraft that is to be refueled captures a drogue apparatus. Refueling
drogues can be passive (not controllable but stable) or controllable using an airfoil-rudder
arrangement. In the design of the PCUAV rendezvous system a drogue whether
controllable or passive is captured by the minis. After capture and drogue insertion into
the mini's fuselage, the parent pulls the mini back to its wing, the same point at which it
was initially separated. The mini is pulled upward to a wing contact point where it is
simultaneously forced horizontally by the dynamic wing pressure. The mini is then
positioned and aligned properly by the parent clamping system. This alignment allowed
for the pinpoint insertion of the mini one-way fuel nozzle and the reestablishment of
contact between the electrical surface points. As the parent clamps the mini, the fuel-line
doors are opened allowing for free transfer of fuel. The completion of this final step
completes the rendezvous of the PCUAV system.
Figures 5.3.1 and 5.3.2 present the initial designs for a controllable drogue and a
C130-type passive drogue respectively. The mini captures these drogues, approximately
five to ten centimeters in maximum dimension. Key characteristics that these drogues
must portray are stability. They must stay in a fixed position for as long as possible.
Such a position fix will allow the minis enough time to perform the potential planning
and control in the capture procedure. (Ref. 21, 22)
)13
Figure5.3.1 ControllableDrogue (with Airfoil)
9,0942
Figure 5.3.2 PassiveDrogue (Based on C130 Design)
Capture of the drogue by the mini is crucial to this strategic design. The mini must
align its flight path with that of the drogue using a camera in its fuselage nose. After the
alignment process occurs the following procedure steps occur:
1) Mini opens its fuselage mouth via a pulley-track system.
2) Using the camera, the pilot operator at the PCUAV ground station must guide the
mini, so that the stable drogue inserts into the mini rendezvous compartment.
3) After capture, the mini mouth closes, keeping the drogue in its mouth.
Figure 5.3.3 depicts the mini mouth opening and closing. Mechanism was
initially designed to guarantee redundancy in the capture. A mouth opening which is
bigger than the drogue size allows the operator with sufficient error in capture. Other
simplified mechanisms have been studied. Such designs include capturing the drogue in
a wedge created on the mini's fuselage. This decreases complexity but there exists
problems with pinpoint drogue insertion.
Actual door opening and closing mechanism is seen in Figure 5.3.4. Slide-able
door arrangement allows for a smooth and fast capture.
A study was also performed to better understand what the maximum rendezvous
distance (between parent and mini) could be achieved with out potential complications.
Parent pulley-spindle system that pulls the captured mini back to the wing potentially
could hold thirty meters of tethered cable. Cable thickness was estimated to be 0.5
centimeters. Tether cable could be designed to be thinner or potentially transfer data (i.e.
fiber optics, Ethernet, WLAN, analog & digital signals). Table 5.3.1 presents the
analysis performed.
Figure5.3.3 Drogue Capture
Drogue
Sliding
Door
Figure5.3.4 Mini Rendezvous System
Table 5.3.1 Rendezvous Cable Analysis
Spool Diameter(cm)
1
Outer Diameter(cm)
12
Spool height (cm)
3
wraps
wrap levels
cable thickness (cm)
11
6
0.5
cable length
508.68
total cable length (cm)
3052.08
total cable length (m)
30.5208
CHAPTER 6
6.1
Summary, Recommendations, and Conclusions
Prototype
During the process of development of a complex integrated vehicle system
PCUAV, a prototype design was required to test the identified technical challenges and
potential hurdles. This prototype could be a full aerodynamically clean design as laid out
in earlier sections, or it could be an off-the-shelf UAV (i.e. Telemaster) retrofitted to
meet the PCUAV requirements. It was deemed extremely advantageous to design a
parent-mini vehicle from the ground up. It is evident that the design of the mini is greatly
affected by that of the parent and visa versa.
Many members of the PCUAV team felt that the biggest hurdle for this project was
the systems integration and cooperative mission performance planning (i.e. software,
mission planning, etc.). By using a retrofitted off-the-shelf vehicle, the systems
integration and software/electric development would be atop the team's priorities.
A pragmatic approach can be efficiently achieved by performing both tasks in
parallel. The team can thus learn from the generic UAVs performance, during a mission,
and design appropriately. Generic UAVs, allow for tests to be performed sooner rather
than later. This will allow team members to gather data important to the technical
hurdles encountered. Such research is greatly beneficial to any project.
An immediate goal for the PCUAV project should be to choose one of the PCUAV
integration concepts as well as a parent-mini separation system, with potential for
rendezvous. An important goal of this project is to build a prototype PCUAV system and
evaluate it. As time is an important factor for this project, retrofitting a generic UAV in
conjunction with the actual development maybe a good approach.
6.2
Future Effort
In order to demonstrate a number of PCUAV technologies, a demonstration
program objective must be established. By demonstrating new technologies derived by
this concept or unobtainium, further research work can be targeted in the proper and most
successful directions. DARPA feels that UAV platforms may also be used to test
maturing subsystems and their technologies. For example, the Pioneer UAV was tested
in April 1995 with a surface acoustic wave (SAW) sensor, which can be used against
chemical agents. DARPA has consistently maintained that a vigorous but disciplined
approach to technology development is the key both to achieving objective architecture
capabilities and keeping costs in an affordable range. (Ref. 12)
A number of tests have been identified for potential immediate processing:
Vehicle
1)
Deployment and precision delivery of micro-UAVs.
2)
Safe deployment of mini UAVs.
3)
Integrated fuel/power system - transfer energy and then release.
5)
Precision deployment of micro-sensors by mini UAVs or the parent UAV.
6)
Precision deployment of Pallets.
7)
In-flight recovery of mini UAVs - automation, GPS coordination.
8)
In-flight refueling, recharging of mini UAVs.
Electrical
9)
Potential radio ranging.
10)
Redundant computer integration.
11)
Cooperative operation of multiple PCUAVs.
12)
In-flight recovery mission planning.
These demonstrations will lay the foundation for further advancements in the
PCUAV field. The MIT/Draper team has a realistic outlook for future of the PCUAV
initiative. In five to ten years, with the expected advance in technologies related to micro
aerial vehicles, GPS, and other micro-mecahnical sensors, such a system could be
operational. Figure 6.2.1 depicts the state of maturity for both present and future UAVs.
DARPA initiatives are targeted to reach maturity by the year 2003. As DARPA is
presently a major driver of MAV technology and because the PCUAV relies heavily on
such vehicles, the team projects the PCUAV's operational capability to be in five plus
years.
UAVs
Hunter
Pioneer
Pointer
Exdrone
Predator
Operational
Present
Navy VSTOL
Eacyle Eye
Outrider
Dracyon
Sender
Global Hawk
Darkstar
Operational
2-5 years
DARPA initiatives
NRL concepts
PCUAV
MAVs
Technology
5+ years
Figure 6.2.1 State of UAVs
6.3
Cost
Cost of an unmanned aerial vehicle is an important subject. UAVs can range from
thousands to millions of dollars. Predator vehicle's projected cost is $62 million per unit.
On the other hand, Sender's projected cost is approximately $20K to $25K whereas
MAVs are projected to be in the $5K to $15K range. Because the PCUAV system
integrates three tiers of vehicles with different costs, expendability and costs are
important issues. Many experts in industry feel that MAVs should be designed to be
expendable. After a MAV accomplishes its mission, it either self-destructs or is lost in
the mission zone. Minis on the other hand could potentially be valuable and nonexpendible. The PCUAV has the option of retrieving the minis, but presently does not
capture the micros. (Ref. 12)
Col. John Blitch of the DARPA UGV initiative, as mentioned earlier, believes the
PCUAV system without the micro vehicle cargo, should not exceed $50K in cost. Thus
the two minis and the parent would have to be designed to be affordable. (Ref. 9)
Expendability can be measured in cost as well as potential data. Parent or minis
could have on board data storage. If so, there exists the potential desire to have them
return to friendly confines. Cost of the PCUAV system will be an important driver of the
concept. If certain losses, such as MAVs or UGVs, are not acceptable the concept must
be altered. While a proper cost analysis has not been a top priority for the PCUAV team
thus far, it potentially should be in the near future.
6.4
Conclusions
The three-tier unmanned aerial vehicle proposed in this thesis is a state of the art,
innovative concept which has both national and international applications. UAVs aid
humans in performing difficult or hazardous tasks. It allows operators to perform
missions, which require high altitudes, medium altitudes and low or ground altitudes.
The PCUAV is a multi-class vehicle. For military applications this is very beneficial, as
it has the ability to perform an array of missions. Instead of having the need for three
UAVs, that take up space in vehicle size and equipment and have high costs, only a
single UAV system is needed.
In five years, the PCUAV should be an important vehicle, as it has the ability to
transport and extend the intelligence of smaller UAVs (i.e. MAVs). If industry's goal is
to decrease the size of vehicles yet increase the ability of these vehicles the PCUAV
concept is extremely favorable.
6.5
Recommendations
For future development of the PCUAV concept, a number of issues must still be
researched. While the tier system has advantages, tests and demonstrations must be
performed in order to validate its importance. Such validation must be compared to
potential competitors, for example a swarm of Sender vehicles. Because MAV
technology is still in the development phase a proper understanding of what the future
holds must be projected. Only then can a PCUAV system be successful. Future work in
the PCUAV arena must also be targeted toward vehicle development. This will allow for
better understanding of important design and system issues involved with the concept. A
retrofitted off the shelf UAV, as mentioned earlier, may be a good test bed for testing.
Such testing may include electronics validation, avionics performance, communication
reliability, parent-mini separation and integration, software reliability, etc. Testing of the
PCUAV concepts will potentially drive the advancement of the vehicle.
It may also be beneficial to better understand what DARPA and other agencies
want from the PCUAV. While numerous agency and industry contacts have been made,
it is important and necessary to keep tabs on these contacts through future phases of
vehicle development. Many agencies change personnel as well as philosophies extremely
rapidly. It is imperative to the project's success to understand and identify these changes.
All in all, the PCUAV concept will develop with hard work and the constant
knowledge of how the UAV industry is changing.
References
1) UAVs, http://web-ext2.darpa.mil/tto/mav/mav_auvsi.html. 1998.
2) "World Markets for Military, Civil & Commercial UAVs," Report 5375. 1998.
3) Martorana, Richard. MAV System/Subsystem Specification. Draper
Laboratory, Inc, 1999.
4) Predator Home Page, http://www.peocu.js.mil/Predator/INDEX.HTML. 1998.
5) Global Hawk, AUVSI99. Association for Unmanned Vehicle Systems
International, http://www.auvsi.org/auvsicc/uav.htm. 1997.
6) "Sender Drone: Concept of Operations." Naval Research Laboratory
Documentation. 1998.
7) "Man-Portable, Rocket-Propelled Surveillance Vehicle Model Rocket Design
and Construction," by Alankar Chhabra, Bachelor's of Science Thesis, MIT,
June 1998.
8) A meeting with Dr. James McMichael, DARPA MAV Program Manager,
August 1998.
9) A meeting with Col. John Blitch of the Army, the present DARPA UGV Project
Manager. October 1998.
10) Streeter, Victor L; Fluid Mechanics, Fourth Edition.McGraw-Hill, Inc.
Copyright 1966.
11) Hoerner, S. F.; Fluid - Dynamic Drag, Published by the author. Copyright 1965.
12) 1997 DARPA UAV Annual Reports.
13) "MAGIC2, Multiple Aircraft GPS Integrated Command and Control System."
Herley-Vega Systems, A Division of Herley Industries, Inc. 1996.
14) "Low Weight, Zero Maintenance Long Endurance SOFC for MUAV." IGR
Enterprises, Inc. 1998.
15) "RF Decoys and Multimission Payload Delivery Platforms." Naval Research
Laboratory. 1998.
16) 1998 Shephard's Unmanned Vehicles Handbook. The Shephard Press 1997.
17) Model Aviation. September 1998. The Academy of Model Aeronautics, Inc.
18) Genesys, In-flight Generator System. Model Airplane News Product Review.
1997.
19) Aveox web site, http://www.aveox.com. 1999.
20) R/C Report. January 1999. RC Report Corporation.
21) Douglas, John; "Controllable Drogue for Aerial Refueling." 1981 IBM Patent.
22) C-130 documentation: U.S. Air Force. http://www.cl 30.com/index.html. 1999.
23) Collaboration with PCUAV teammate, Mr. Sanghyuk Park.
24) Collaboration with PCUAV director, Mr. Charles W. Boppe.
25) "The Parent Child Unmanned Air Vehicle Concept study," by Tarek S.
Nochahrli, Master of Engineering Thesis, MIT, May 1999.
26) "Cooperative Parent Child Unmanned Aerial Vehicles: A Systems Approach,"
by Anand Karasi, Master of Engineering Thesis, MIT, May 1999.
Appendices
Appendix A
Power-Propulsion Study
IC Engine, Battery, Fuel Cell Database
ISystem
Power
IC 100 cc single cyl 2-stroke
IC 75 cc twin cyl (24X10 prop)
IC 62 cc single cyl (18X10 prop)
IC 40 cc single cyl (18X10 prop)
IC 25 cc single cyl (17X8 prop)
3W-24 Engine
Brushless 1412/6Y (8X6 prop)
Brushless 1406/12Y (8X6 prop)
Brushless 1406/4Y (8X6 prop)
Brushless 1406/4Y (8X6 prop)
Brushless 1406/2Y (7X6 prop)
Brushless 1406/2Y (8X6 prop)
8 hp
6 hp
5 hp
2 hp
2 hp
2.5 hp
24 A @ 12 V
?A @ 12 V
17 A @ 7 V
30 A @ 10 V
47 A @ 7V
58 A @7V
NiCad Tamiya Flight Pack
NiCad Tamiya Flight Pack
Lithium Sulfur Chloride - AA
Lithium Sulfur Chloride - C
12 2 Ah Lithium Sulfur dioxide
Advanced Lithium Batteries
Nickel Hydrides
on-board generator (gas to elec))
1400 mAh 8.4 V
1800 mAh 8.4 V
1.6 Ah 3.8 V
6.2 Ah 3.8 V
150 W.hr (6V)
100 watts*hr/kg
Strip Membrane Fuel Cell
Stack Bipolar Platte Fuel Cell
Strip Type Fuel Cell
IGR Enterprise Fuel Cell
1 volt
2.8 volt
2.8 volt
Cost
Throughput Thrust Vendor
Weight Volume
ounce cubic inch
ounce
($)
140
5 32:1 oil
Zenoch
120
4.5 32:1 oil
Zenoch
1850
80
3.8 32:1 oil
Zenoch
599.95
70
2.3 32:1 oil
Zenoch
269.95
55
1.4 32:1 oil
Zenoch
259.95
2.6 Ib
1.42
3W Giant Scale Motors
10.02 1.47" DX 2.36" L electric
Aveox
7 1.47" D X 1.76" L electric
Aveox
6.9
2.6 electric
41 Aveox
119.95
6.9
2.6 electric
24 Aveox
119.95
6.9
2.6 electric
33 Aveox
119.95
6.9
2.6 electric
41 Aveox
119.95
20
20
4
6
40
14
14
.5" Dby 2" L
1" D by 2" L
14
electric
electric
electric
electric
electric
electric
6 watts generated
strikealite
strikealite
Great Batch
Great Batch
Saft, Inc.
TADIRAN
Genesys
16
9 hydrogen, air
27 solid-oxide
9 solid-oxide
carbon
Dr. Roland Nolfe
Dr. Roland Nolfe
Dr. Roland Nolfe
DARPA-Gordon
216-464-1255
Appendix B
Tube Launch for PCUAV. (smart missiles - controlled by operator)
Potential Benchmarks for PCUAV Launch
Tube-Launch Missiles
Name
Country
BM-24
BM-27
BGM-71A TOW
Swingfire
LAW 80
M48 Chaparral
Sidewinder
DARD 120 SEP
AT-4 Spignot A
AT-4 Spignot B
SAKR
BM-21
RM-70
FGM-77A Dragon
Bofors BILL
M2 Carl Gustav
B-300
MBB Cobra
M20 Super Bazooka
D-3000
FIM-92A Stinger
FIM-43A Redeye
Milan, Milan II
Russia
Russia
US
UK
US
US
US
France
Russia
Russia
Egypt
Russia
Russia
US
Sweden
Sweden
Israeli
France
NATO
Egypt
US
US
Italy
Length
Diameter
Weight
Launch Type
Range
ft
inch
10
8.6
6
6
5.5
5
5
5
5
5
5
5
5
4.5
4.5
3.7
3.5
3.5
3.5
3.5
2.75
2.75
-
lbs
103
46
81
TLR
TLR
TLWGM
TLGM
TLGM
TLS
TLGM
TLR
TLGM
TLGM
TLR
TLR
TLR
GTST
TLGM
TLGM
TLWGM
GLWGM
TLR
TLR
SLR
SLR
TLR
yds
11,00
30,000
500 - 4000
4370
550
16,000
655
70 - 2000
75 - 2500
30,00
15,00
15,000
70- 1000
2190
492
440
2190
109
1760
5200
2520
6.5
6.5
3.5
6
5
9.5
9.5
4
4
4.5
7
8
5
2.5
4.5
3.5
4.5
3.5
4
8
5
4
4.5
185
190
28
30
30
39.5
42
24.4
94
16.5
17
22
10
35
29
38
GTST Gas Tube launcher (pyrotechnic generated), with side thrusters and sustainer rocket
CLGP Cannon Launched Guided Projectile
SLR Shoulder launched single rocket solid motor
TLS Truck/trailer launched rocket with sustainer
TLBS Truck/trailer launched rocket with boost and sustainer engines
TBLR Trailer mounted Box launched single engine solid motor
TBGM Truck/trailer mounted box launcher (i.e. similar to Patriot)
TLGM Tube launched guided missile
TLR Tube launched unguided rocket
TLWGM Tube launched wire guide missile
Speed
mph
625
M2.5
Supersonic
230
M2.5
M2.5
Appendix C
Children packaging on Parent (possibilities)
* Wing Loaded
-'--4-
* Fuesalage Loaded
I
"ll
C===
I
BB~BD
* Nose Loaded
(0
Appendix D
Draper Ground Station
*
*
*
*
*
*
*
*
*
Win NT/QNX system
safety pilot in the loop
3 attenna: comm, GPS, video
Automated mission planning, geolocation
Demonstration planned in July (Helicopter with UGV)
Old system tested w/ helicopter at 1500 ft max height
Early development limited to 2 to 3 vehicles
Mission planning performed at GS level
Waypoint data streams
GS Contacts:
Comm RF Modem
Multi-Vehicle Comm
Hardware
Lead
Chris Sanders
Bob Tingley
Tony Larusso
Steve Kolitz
Summer Demo - Scenario Overview
* UAV dispatched using a man portable Vehicle Control Unit (VCU) to zone within
line-of-sight
* UAV carries a UGV/sensor to perform a targeting and battle damage assessment
mission
* autonomous mission planning (VCU) determines waypoint list determined via UAV
aerial imagery.
* Waypoint list is uplinked so UAV will continue to execute plan if comm lost
* UAV goalpoints include the UGV deployment point
* At operation zone, UAV optically geolocates potential targets for precision weapon
delivery and point placement UGV.
* Operator uses video from UAV to provide goalpoints and constraints for the UGV
* Autonomous mission planning system generates route plan for UGV mission
PrimaryObjectives
*
*
*
*
*
*
Estimate GPS coordinates of UGV destination via UAV maneuvers (geolocation)
Independent (mutually exclusive) control of both UGV and UAV from VCU
Continued autonomous operations when comm lost
Basic UGV autonomous guidance using DGPS.
High speed UAV flight
Autonomous UAV and UGV mission planning
FunctionalRequirements
Air Vehicle
* Digital compass providing +/-2 deg heading accuracy with +/-45 degree tilt.
* Line-of-sight UAV to VCU communications (separate data and video links)
Ground Vehicle (COTS)
* Avionics kernel based on SARV avionics
* Autonomous guidance capable electronics, including DGPS
* Line-of-sight UGV to VCU comm (separate data &video links)
* LOS Tele-operation capable from at least 1500' distance
Vehicle Control Unit (VCU)
* Independent (mutually exclusive) control of one UGV or UAV from the same unit
* Provide interface(s) to human operator to support ground target geolocation, manual
mission planning, payload control, vehicle location status, & vehicle systems health
status
* Optical geolocation will be performed using pilot assist commanded changes in
bearing to the target along with human operator "target detection"
* Provide inner loop control software capable of enabling > 50 MPH forward speed for
SARV
* Provide time tagged and correlated video frame/human designated pixels/onboard
SARV navigation state information to situational awareness
* Incorporate frame-grabber to allow capture of human designated ground target
* Provide communications ground support equipment (GSE) capable of 19.2kpbs
command uplink and telemetry downlink.
* Provide communications GSE for UAV EO video and TBD ground robot
drive/payload camera
* Provide navigation ground support equipment for DGPS using Novatel ground
receiver station to BOTH UAV and UGV.
Appendix E
Power Systems
* Cylindrical Lithium cells developed by TADIRAN
* TL-4903 C size
* Nominal Voltage of 3.6 V
* Nominal Capacity of 8.5 Ah
* Dimensions: 1.031" diameter, 1.97" height
* 5 to 8 cells in series may meet main power needs + 2 cells for auxiliary power
* Use DC to DC converters to adjust power sources for subsystems.
* Apex Micro-technology DC-DCconverters
* Need to due trade studies between Nickel Hydrides and Lithiums
* In Flight recharging of batteries may be a problem as take long time
* Willing to review electrical power management system
Engine Systems
* COTS engine .75" to .90" 2-stroke engine
* 2 to 2.5 horse power should be sufficient
3W-24 Engine by 3W Giant Scale Motors
* 24cc/1.42 in^3
* 2.5 HP
1500 g common fuel
* 2.65 lb
3.9"L X 2.75"W
* Propl8X10
* $500
In-Flight Generator
* Sullivan Products Genesys
* Can provide up to 6 volts at 750 mA (max direct current)
* Possible source for auxiliary power
* MAVs (idle), camera, transceiver
* Possibly recharge batts = 200 mA charge rate
* $660
Batteries
*
*
*
*
*
*
*
Rechargeable TADIRAN Lithium Batteries
Model TLR-7103
15.0 mm X 50.5 mm
17 grams
2.8 V @ 250 mA
250 mA max charging rate to 3.45 V
Problems with recharging
Temperature regulation
*
*
Time
Additional recharging circuits
Microwave radiation refueling
*
*
*
*
RF-DC conversion in some apps (85% efficiency)
Jenn, Vitale of Navy tested system with Lutronix MAV & 12 kW - 1.3 GHz ground
source
Potential use with Mother & 500 watt power (amplified) source if MAV is 5 m away
Use dish reflector attennae to transmit
Fuel/Power Schematic
Preliminary Fuel/Power System
enerator
Main Power Source
Recharge
AuxiliaryAuxiliary
Power
Source
20 V @ 500 mA
Li
FurA/D
Li
Li
Li
Li
Con FPCMCIA
MAV
Figure E-1 Preliminary Fuel/Power System
Li
RF Xm
RF Xt
Appendix F
PCUAV Wrinkles
Parent
200
feet
Umbilical
Power
Data
Navigation
Children
rie3tllssllIsrr
m
ffi 11
IIIE*Bi~
_-
w
I --,Mr
-ra
I6M&
~ ~
Figure F-1
0
.......
-o°0...
0
-4-
/
/
i
-4--
I
r/
,.
/
\
'
rI\
s/ 1
I
s
S
0..
%
°
s
%%
%%
s
*
%
%%
%
s
%"
%
'
'Cs~i~s~BB~iBB~$BB~
Figure F-2
%.
Landing Technologies
Air Bag System
* Air bag: sodium azide (NaN 3) to decompose
explosively, forming sodium and nitrogen gas
* Pack system into a 6 " X 6" X 6" brick
* Can substitute into modular fuselage with micros
* Trigger system immediately before belly landing
Appendix G
PCUAV - Stinger Missile
A lightweight, man-portable, shoulder-fired, missile weapon for air defense of troops.
Crew consists of a chief, gunner, and vehicle carrying the basic load of missiles.
Missile features a dual thrust motor, and an eject motor
launches the missile a safe distance from the gunner prior to rocket motor ignition.
*
*
*
*
Stinger Specs
*
*
*
*
*
23.0 lbs
2.75 in.
5 feet
4 km
11.5 lbs
Weight
Diameter
Length
Range
Launch (Tube)
WASP stage
Wing Deployment
Parent Separation
Ejector Propellant Ignition
_- -t A
r(l- ---1^1-I T --nouler Launcn Apparatus
Rocket Propellant Ignition
....
d___
Appendix H
Sender Trip Report
On October 22, 1998
Meeting with Barry Walden, Chris Bovis of the Naval Research Lab, Washington D.C.
Discussion centeredaround the NRL Sender and Parent-Childconcepts.
*
*
*
*
*
Barry Walden works directly under Rick Foch, director of NRL UAV concepts.
Extensive knowledge in the SENDER & development of UAVs. He is also involved
in ship decoy system.
ChrisBovis works directly under Rick Foch. Direct knowledge in UAV design and
dynamic flight.
NRL Vehicles include: SENDER, Swallow, MITE, FLYRT, Dakota, Eager, 12'
Telemaster, Titan Tornado. Most designs were observedfirst hand.
DARPA is on a 5 year project with a funding of 35 M.
NRL is in its 3rd year of its 5 year program with a funding of 7M.
SENDER
* Developed in a period of 2 months with three people (but with the knowledge and
experience of previous designs ( V tail - staggered tails etc.)
* Sender is a Stage 6.2 - Applied Research vehicle
* Present NRL goal is to develop SENDER II, which will have an increased payload
volume yet keeps its suitcase storability.
* Sender will close towards operation when requirements are specified. At this
moment there are no customers.
SENDER Technologies
* NRL is working with IGR enterprises in the implementation & development of solid
oxide fuel cells. These cell are carbon + air based and DARPA funded. Such a
system has problems with high Thermal generation. Yet the goal is to use it to
replace Lithium batteries. This fuel cell will decrease weight, increase power, and
increase extraction rate. (Electric batteries equal 30% of Sender weight)
* Electric power was used as it is quite, storable, easy of use, no need to flush system or
refuel.
* NRL has internally developed an auto-pilot system, staggering tails design, and a
unique composite aerodynamic airframe.
* This airframe is a fiber glass -thin shell construction that weighs 1.5 - 2 lb.
Manufacturing took about a weeks time.
* Sender's long range is determined by efficient DC brushless motor and low drag.
They are having flight test trouble due to rolling winds as there is a limited aileron
design.
SENDER Manufacturing
* Manufacturing cost for Sender is listed between $5K to $7K. This does not include
avionics. Breakdown: Motors ($500), Airframe ($2K), Batteries ($500), Avionics
($10K), Sensors ($2K)
* Sender was targeted to be < $20K. (Pointer range)
PotentialResearch Opportunities
* Electric Micro-radar UAV, deployed by soldiers for signal jamming. They have a
2km range and need less than 1W power consumption. (AUVSI -97 Proceedings)
* Autonomous shipboard recovery system - ship detects the IR image of the
approaching UAV and sends the corrections to the UAV.
* Chemical sensors: piezoelectric crystals are excited with a frequency when exposed
to a chemical cloud, the frequency changes and the chemical is detected. Such a
sensor is a move away from existing laser systems.
* FINDER - UAV deployed from Predator. Attached to existing harp points. Chemical
detection
(SolCad) after Tomahawk strike. Predator is used as a signal relay device.
* SWALLOW has a unique BIO sensor. (A UVSI - 98 Proceedings)
* Northrop-Grumman test - 4 UAV drone coordination from single ground station.
Demo was 4 months ago.
* Flight Navigation - Path following - NRL Jeff Barrows.
* Special operations seem to be very important as they need these vehicles the most.
Their performance and mission success is greatly improved with the use of these
vehicles. They have the funds and the need. However their requirements are very
difficult to meet. (Research Capstone Requirement document - Rich Bishop)
* Don't use nets - Navy 'hates them.' Year 2003 Pioneer will be obsolete. Navy likes
VTOL.
Recommendations from NRL
* NRL favors electric power, thought we should probably be using electric for our
year design to keep
the complexity down.
* CREDA (Cooperative Research Development Agreement.) Means for sharing
information and working together.
* Build Parent with excess cargo margins & capacity
* To handle unknowns
* Flexibility
* Attract additional customers
* Suggestion for us to use Telemaster as a prototype test-bed.
1 st
Appendix I
Motor Tables - Aveox Model Airplane Motors
Motor
Stato Cont/ Max Speed Const.
r/
Current or rpm/ volt (Kv)
Roto Max Pwr
r
lengt
Torque Ohms
Const.
(Rt)
InOz
/Amp (Kt)
No
Load
Amps
(Io)
Weight, Length,
Diameter (inches)
Typ. Cell Recom. Prop
Count
(cells)
Most efficient
Current at
specified
voltage
8.7oz 2.06 x 1.47
8.9oz 3.3xl.5
lOoz 3.6xl.5
10oz 3.6x1.5
10.2oz 3.3x1.5
10oz 3.6x1.5
14oz 3.9xl.5
6.9 1.76xl.47
8.7oz 2.06x1.47
6.9 1.76xl.47
6.9 1.76x1.47
6.9 1.76x1.47
8.7oz 2.06x1.47
8.7oz 2.06x1.47
8.7oz 2.06x1.47
10.2oz 2.36xl/47
10.2oz 2.36x1/47
10.2oz 2.36x1/47
10.2oz 2.36x1/47
10.2oz 2.36x1/47
12.2oz 2.66x1.47
12.2oz 2.66x1.47
12.2oz 2.66x1.47
12.2oz 2.66x1.47
7
7-10
10
10-16
12-18
12-18
27
5-8
12
5-8
6-12
9-15
7-12
8-18
8-20
8-14
8-14
10-24
12-28
16-30
6-24
10-30
10-30
10-30
77A @6V
71A@ 6V
133A@8 V
91A@llV
inche
F5D Pylon
F7LMR**
F10 LMR*
F12LMR*
V12
F16 LMR*
F27*
RC 7 Oval
Marine 12
1406/2Y
1406/3Y
1406/4Y
1409/2Y
1409/3Y
1409/4Y
1412/1.5Y
1412/2Y
1412/3Y
1412/4Y
1412/5Y
1415/1.5Y
1415/2Y
1415/3Y
1415/4Y
.6
.6
.6
.9
.6
.9
1.2
.6
.9
.6
.6
.6
.9
.9
.9
1.2
1.2
1.2
1.2
1.2
1.5
1.5
1.5
1.5
500W
500W
80A
70A
40A
60A
70A
34A/ 80A
35A/ 80A
35A/ 80A
25A 55A
18A/ 40A
40A/ 90A
25A /60A
20A/ 45A
40A/80A
45A/100A
30A/70A
22A/50A
17A/40A
70/150
50A/100A
40A /80A
25A/50A
3 versions
1000
1000
700
540
540
400
4000
1950
3000
2000
1500
2000
1333
1000
2085
1450
955
725
585
1500
1190
795
595
1.186
1.300
1.931
1.931
2.504
3.380
.451
.693
.451
.676
.901
.676
1.014
1.352
0.645
.932
1.416
1.865
2.311
.9013
1.136
1.699
2.27
.008
.0045
.009
.037
.018
.020
.018
.020
.018
.037
.060
.020
.040
.069
.010
.018
.045
.065
.105
.015
.020
.050
.080
5x5 (7)
14.5x10.5
12x9
14.5x10.5
12x9 APC
14.5x10.5
15x13(27)
Oct. 1747
8x4 (7)
9x5 (8)
9x5 (10)
9x6 (10)
9x6 (12)
9x6 (14)
10x6 (10)
10x6 (10)
9x6 (18)
9x6 (21)
9x5 (24)
75A@18V
80A@25V
31A@7V
47A@7V
31A@7V
21A@ 0V
17A@14V
47A@7V
21A@10V
16A@14V
51A@10V
51A@10V
24A@ 16V
19A@24V
15A@30V
11x6 (14)
36A@14V
1817/2Y
1817/3Y
1817/4Y
2310/4Y
2310/6Y
2315/6Y
2315/8Y
40A/ 80A
25A/ 49A
19A/ 38A
3200W
3200W
3500W
3500W
650
433
325
450
360
248
185
2.080
3.120
4.160
3.004
3.756
5.452
7.308
.027
.060
.018
3.0
1.2
.6
.117
.147
20.2oz 3.43xl.79
20.2oz 3.43x1.79
20.2oz 3.43x1.79
26oz 2.75x2.25
26oz 2.75x2.25
30oz 3.25x2.25
30oz 3.25x2.25
20-28
20-36
20-40
12x6 (27)
42A@24V
19A@30V
13A@36V
IndustrialMotors
Aveox Industrial High power motors. (not designed for 11406
servo applications)
V12Y
__
Nominal Voltage(all motors at 6,000 rpm no load@ Vp) 12
Continuous stall torque *In-Oz @ 250 C
15.5
Motor constant (InOz/root watt
3.46
Friction Torque 5Krpm
1.299
Maximum Speed (rpm)
30,000
0.606
DC Resistance (Ohms)
Speed Constant (RPM/Volt)
500
Torque Constant (InOz/Amp
2.69
Outside diameter
1.47"
Shaft diameter
5mm
length
1.76
weight
7.0 oz
rotor/stator length
0.6"
1406
/24Y
24
15.5
3.46
1.299
30,000
2.422
250
5.38
1.47"
5mm
1.76
7.0 oz
0.6"
1406
/48Y
48
15.5
3.46
1.299
30,000
9.688
125
10.76
1.47"
5mm
1.76
7.0 oz
0.6"
1409
/8y
12
17.6
5.31
1.995
30,000
0.257
500
2.69
1.47"
5mm
2.06
8.7 oz
0.9"
1409
/16y
24
17.6
5.31
1.995
30,000
1.026
250
5.38
1.47"
5mm
2.06
8.7 oz
0.9"
1409
/32y
48
17.6
5.31
1.995
30,000
4.104
125
10.76
1.47"
5mm
2.06
8.7 oz
0.9"
1412
/6y
12
21.9
6.45
2.553
30,000
0.174
500
2.69
1.47"
5mm
2.36
10.2 oz
1.2"
1412
/12y
24
21.9
6.45
2.553
30,000
0.696
250
5.38
1.47"
5mm
2.36
10.2 oz
1.2"
1412
/24y
48
21.9
6.45
2.553
30,000
2.785
125
10.76
1.47"
5mm
2.36
10.2 oz
1.2"
1415
/5Y
12
28.5
7.62
2.034
30,000
0.143
467
2.88
1.47"
5mm
2.66
12.2 oz
1.5"
1415
/9Y
24
28.5
7.62
2.034
30,000
0.444
265
5.08
1.47"
5mm
2.66
12.2 oz
1.5"
1415
/119Y
48
28.5
7.62
2.034
30,000
1.994
125
10.76
1.47"
5mm
2.66
12.2 oz
1.5"