Real World Design Challenge 2013 Submitted by the CCA Innovators Team Member *Team Leader* Athena Kao Alexis Amelotte Devin Slaugenhaupt Courtney Thurston Ian Cavanaugh Jacob Antonio Rick Ciora Ann Camp, Coach, CCA Teacher Mentor Name Bob Camp *National Mentor list* Andrew Kacmar *National Mentor list* Joe Gruenenwald Grade 12 Age 16 12 11 10 9 10 11 - 18 17 15 15 16 17 - Address Phone # 717-486-6066 Email bcamp@vectron.com 815-404-0066 andrew.kacmar@gmail.com 100 Watts Street 251 Edwards Street n/a 814-797-0240 Email skieslily@gmail.com shakespeareanlover1215@yahoo.com awesomeflyer1@yahoo.com thurscon@gmail.com technomageapprentice@gmail.com turtle3@windstream.net rickciora@gmail.com acamp@connectionsacademy.com n/a Matthew Del Buono n/a n/a mpdelbuono@gmail.com Grant Schneemann n/a n/a grant.schneemann@faa.gov Commonwealth Connections Academy 4050 Crums Mills Road Harrisburg, PA 17112 (717) 245-0342 March 16, 2016 Team/Coach Validating Signatures: A Camp Coach Before & after, coach, and progress surveys: all completed A Camp Objective Function Value: 311100.52 dollar hours, Search Time: 20.493 minutes 1 Executive Summary The goal for this challenge is to design an Unmanned Aircraft System (UAS) consisting of one or more Unmanned Aircraft Vehicles (UAV). The UAS has to be capable of searching for and identifying a child lost somewhere within the given two-mile radius search area of Philmont Ranch. In the conceptual design phase, most of our activities involved research. Team members examined other unmanned aircrafts that are used in the real world to find models efficient enough to provide us with an idea of the kind of UAV we would like to develop. We then began to search for airfoils and constructed basic designs that incorporated the concepts we had discovered. For the preliminary design, we continued our research and began to flesh out the designs with the provided worksheets and computer-aided design software. We first identified the combination of sensor payloads that would provide a wide scanning camera footprint. Next, we created the UAV model that could contain all the needed components in the fuselage. We searched for airfoils that would provide high lift for our aircraft, and then started to test each option to find which would be most suitable for our design. It was here that we began to significantly consider the performance viability of our aircraft. We did the performance analysis on each design, which determined our selection of airfoil and wing configuration to move onto the detailed design phase. Finally, we strove to perfect our chosen design in the detailed phase. Members worked on the business planning and mission planning revolving around our detailed design, while the design team focused on perfecting our UAV and conducting mission analysis to ensure efficiency and minimize the objective function. We made the choice to reduce cost and design an environmentally friendly, quiet UAS by changing our propulsion system to the E-20 electric engine. Our two final designs are: Wing Planform Area (in ) Wing MAC (in) Wmtow (lbf) Wbattery (lbf) Alphastall (deg) Maximum Lift Coefficient Vmin at 8000 ft MSL(mph) Engine Max Power (hp) Power Loading (lbf/hp) Propeller Efficiency Static Thrust (lbf) Design 1 (X1000 + X3000) 540 8.25 34.96 3.70 12.198 1.837 50.253 2.414 14.483 0.8 13 Design 2 (X3000 only) 540 8.25 34.41 3.70 12.198 1.837 49.856 2.414 14.255 0.8 13 Propulsion System Selection E-20 engine E-20 engine Engine(motor) Efficiency Wing Loading (lbf/ft2) Distance to Clear 50ft Obstacle 0.96 9.3227 189.995 0.96 9.176 184.492 2 2 Table of Contents 1 Team Engagement ..................................................................................................... 5 1.1 Team Formation and Project Operation ................................................................. 5 1.2 Acquiring and Engaging Mentors ........................................................................... 6 1.3 State the Project Goal ............................................................................................ 8 1.4 Tool Set-up / Learning / Validation ...................................................................... .10 1.5 Impact on STEM .................................................................................................. 12 2 Document the System Design ................................................................................. 13 2.1 Conceptual, Preliminary, and Detailed Design ..................................................... 13 2.1.1 Conceptual Design (Many Solution Candidates) ........................................... 13 2.1.2 Preliminary Design (Few Solution Candidates) ............................................. 22 2.1.3 Detailed Design (One Solution Candidate Refined) ....................................... 32 2.1.4 Describe lessons learned .............................................................................. 34 2.1.5 Describe project plan updates and modifications .......................................... 35 2.2 Detail the Aerodynamic Characterization ............................................................. 36 2.3 Selection of System Components ........................................................................ 41 2.3.1 Propulsion System ......................................................................................... 41 2.3.2 Sensor Payload Selection .............................................................................. 42 2.3.3 Ground Station Equipment Selection ............................................................. 43 2.3.4 Addition UAV/UAS Equipment ...................................................................... 45 2.4 Aircraft Geometric Details .................................................................................... 46 2.4.1 Wing Configuration ........................................................................................ 46 2.4.2 Tail Configuration........................................................................................... 47 2.4.3 Fuselage ........................................................................................................ 48 2.5 System and Operational Considerations .............................................................. 49 2.6 Component and Complete Flight Vehicle ............................................................. 50 2.7 Structural Analysis ............................................................................................... 50 2.8 Maneuver Analysis ............................................................................................... 51 2.9 CAD models ......................................................................................................... 52 3 3 Document the Mission Plan .................................................................................... 55 3.1 Search Pattern................................................................................................................. 55 3.2 Camera footprint………………………………………………………………………………….56 3.3 System Detection and Identification………………………………………….........................60 3.4 Example Mission ............................................................................................................. 63 3.5 Mission Time and Resource Requirements ......................................................... 67 Objective Function Calculation………………..………………...……………………68 4 Document the Business Case…………………………………………………………...69 Overview .................................................................................................................... 69 4.1 Identify targeted commercial applications ............................................................ 69 4.2 Amortized System Costs ...................................................................................... 69 4.2.1 Initial Costs .................................................................................................... 69 4.2.2 Direct Operational Cost per Mission .............................................................. 70 4.2.3 Amortization ................................................................................................... 71 4.3 Market Assessment.............................................................................................. 73 4.4 Cost / Benefit Analysis and Justification............................................................... 74 Works Cited ................................................................................................................. 77 4 1. Team Engagement 1.1 Team Formation and Project Operation Our team is comprised of students with either strong backgrounds or enthusiastic interest in science, technology, engineering, and math: Athena is a senior, and has been a competitor in the Real World Design Challenge for 4 years. She serves as the team leader. Rick is a junior, and has participated in RWDC for 3 years. He enjoys working on the design components of the challenge. Devin is a junior and has been a member of our team for 2 years. He worked to develop our business case. Courtney is a sophomore and has also been on our team for 2 years. She worked on documenting our progress throughout the year. Jacob is a sophomore and also in his 2nd year of RWDC participation. He loves working on the math problems involved with the challenge. Ian is a freshman and this is his 1st year as a member of the team. Ian is interested in design, and worked with Rick to develop several preliminary UAV designs. Alexis is a senior and this was also her 1st year in the Real World Design Challenge. She enjoys reading and writing. We attend an online virtual charter school, so we only met virtually in an Adobe Connect “LiveLesson” room to collaborate every week. Although we initially viewed this situation as a setback and potential detriment, we feel that it has actually become an asset to strengthening our communication skills. Engineering is a field where crystal clear, specific, and frequent communication must be maintained to ensure the development and optimization of a project, so we consider ourselves fortunate to have learned these skills through the Real World Design Challenge. We needed to become extra aware of each member’s progress in order to ensure the completion of each component of our design. 5 This did make it very difficult to find a meeting time that suited all of our schedules, so we met on Friday evenings when everyone could attend. As the challenge progressed, we added meetings on Sunday afternoons and Tuesday evenings to ensure that we allocated enough time to discuss what tasks we had remaining on our itinerary. We also kept in contact via the internal webmail system at our school. Over webmail or at meetings, we would talk about tasks that needed to be completed by the next week and any new developments in our progress. In the conceptual design phase, most of our tasks involved research. For the preliminary design, roles expanded out into continued research, designs, and some testing. Finally, in the design phase, members worked on the business case and mission planning revolving around our detailed design, while the design team focused on perfecting our UAV and conducted testing to guarantee efficiency and minimize the objective function. We found that our method of goal setting was very effective for our environment as we were able to share our documents and collaborate by utilizing Windchill, Dropbox, and a feature in our “LiveLesson” room known as the “Sharepod”. 1.2 Acquiring and Engaging Mentors 6 We as a team knew that it would be best if we chose a mentor that was technical, professional, and could assist us in areas where we weren’t inherently as strong. We brainstormed some traits that we needed to find in our mentor figure. We wanted them to be knowledgeable with airplanes and their designs, physics, and aerodynamics. Also, because of the team’s cyber environment, it was important for us to find a mentor that would adapt to this kind of environment to help the team by dedicating time to communicate with the team virtually. If we chose a mentor that would not be willing to dedicate his or her time to help, the effort we put in to finding great mentors would be futile. Because of this, we chose mentors that were willing to offer their free time to mentor us, and who would be able to communicate frequently with the team throughout the duration of the challenge. We felt that it was very important to have somebody who would commit to working with us through the completion of the challenge without diminishing contact with us. With these criteria in mind, we chose two mentors off of the National List and obtained two further mentors. We retained Mr. Camp, who was a great asset to our team last year, because of his engineering experiences and knowledge of software and cost analysis. Another mentor of ours, Andrew Kacmar, is an aeronautical engineer who also happens to be a nephew of our coach. We were happy to take him on as a mentor given his expertise and experience in the field. We also approached three further mentors, Dr. Gruenwald and Matthew Del Buono, who some of our team members are fortunate enough to call friends. Dr. Gruenwald has extensive knowledge of business and marketing, and we felt as though these skills would assist us greatly as we developed our business case. Matt Del Buono works for Boeing Insitu, one of the world’s leading UAV manufacturers, as a software engineer for embedded systems of unmanned aircraft, specializing in flight automations, fault detection isolation & recovery (FDIR), and built-in tests (BIT). Finally, we gained FAA employee Grant Schneemann as a mentor as well. Due to our unusual method of solely virtual collaboration throughout the project, we felt that having many mentors would complicate communication. Therefore, we found five 7 mentors that specialized in areas where we needed assistance and were also willing to devote their time by means of online contact. After discussion, the team decided to commit to just these five mentors. In addition to these mentors, we are also fortunate to have an extremely knowledgeable and skilled coach, who we consider to be just as much of an asset and resource to us as a mentor. We made contact with these mentors as soon as possible, speaking with Mr. Camp and Mr. Kacmar before the challenge release in September on the first day of school and again after its release in late October, when we also began contacting Mr. Del Buono and Mr. Schneemann. We engaged Dr. Gruenwald as soon as we began working on the business case. As a team, we maintained frequent contact and interacted with our mentors about 2 or 3 times per week. Whether it was through webmail, email, LiveLessons, or through our coach, we communicated with each of them regularly and maintained contact throughout the challenge. As work on the challenge became more involved, contacts with mentors increased substantially throughout the week. 1.3 State the Project Goal Objective Function Part of the state and national project goal was to minimize the objective function. The objective function combines the technical and business aspects of the challenge to analyze the efficiency of the design solution. In this formula: T represents the total time (in hours) required to find the missing child for the example mission, given the worst-case scenario that the search area must be completely scanned by the UAS (using one or more UAVs to achieve total coverage). During the search, the UAS completes an “object detection” event followed by an “object confirmation” event and a successful confirmation of the child. One of each of the three false-matches must occur in each zone. The successful confirmation of the 8 child must occur in Zone 3. Total time also includes the time to complete any required refueling, but not the time required to return to base and land. The 50-yard radius “search center” is the operations area and does not need to be searched by the UAS. C is the “fully loaded” cost of building the system and completing the above mission fifty times. The “fully loaded” cost is initial cost + 50 * operational time * cost per hour. Design Variables Wing and tail geometry including area, aspect ratio, taper ratio, sweep, dihedral, twist, airfoil selection. Propulsion system selection. Fuselage layout, including location of sensor payload(s), transmitter(s), fuel tank, battery, autopilot, and other electronics. Structural design and material selection. Sensor payload and telemetry selection. UAV(s) search pattern. Mission computer selection and other ground-based components. Number of UAVs designed. These design variables contribute to the time and/or cost components of the objective function, and the specifications of each must not violate the constraints of the challenge that is detailed below. Aircraft Constraints The sUAS will comply with RWDC FAA Technical Readiness Guidelines A maximum gross takeoff weight (including fuel) of not more than 55 pounds per UAV. There is no minimum weight requirement. Antennas on-board the UAV must be separated by a minimum of 18 inches to avoid destructive interference. 9 Search operations are conducted at an altitude of 150 - 1,000 feet above local ground level (assume that ground level is equal to the ground station altitude, 8,000 ft MSL). Our choice of flight control hardware, sensor selection, video datalinks and associated ground hardware is limited to cataloged items to be provided. A catalog of propulsion options is provided, but substitutions are allowed. The aircraft must be able to take-off and clear a 50 foot obstacle within 300 linear feet from the starting position. 1.4 Tool Set-up / Learning / Validation Set-up In previous years, our team members encountered many issues with the set-up of tools. Some members were entirely unable to download the tools off the PTC website, so CDs with the programs on them were sent out to the members affected. This took quite a while in some cases because our team is spread out across Pennsylvania. To resolve the issue for this year, we decided to image our machines ahead of time so that the executable files needed for set-up would already be located on the laptops. All we had to do from there was enter product keys where applicable. This worked very well for our team and resolved most our issues with Mechanica, FloEFD, and Creo Elements. We did still have to download MathCad from the internet, but we did not encounter any problems with setting that up. We did encounter issues with signing up for and participating in Windchill, as documented in “Validation.” Learning We met in our LiveLesson room every morning for a week before the State challenge was issued to learn how to use the tools. Our coach guided us through the process of using the CAD software to create a variety of objects including cakes, brownies, doughnuts, and a rough sketch of a fuselage. We also experimented with the software in our free time to practice creating objects of our choice. This helped all team members, returning and new, to become accustomed to Creo Elements. To learn how to use MathCad, Mechanica, OpenVSP, and FloEFD, our team attended the Webinar 10 sessions. Team members became well acquainted with the software required for the challenge during the State competition, and our skills only improved further throughout the National challenge. Validation 1. Windchill One of our members held “pending” status in Windchill for several months, but this did not prohibit him from uploading files or participating in discussions. Another member was initially unable to accept the invitation; they were able to join Windchill, but their account was not automatically connected to our project. After persistent login attempts by this user from the invitation link, the issue appeared to have resolved itself. 2. MathCad We noticed that if the airfoil file was changed to a different name, even if the change was made in the wing definition sheet, MathCad would crash when the performance analysis sheet was run. If only the wing definition sheet is running, this conflict does not occur. 3. FloEFD We experienced issues with FloEFD for Creo where the program was producing invalid calculations when compared with the published wind-tunnel experiment results. We contacted support regarding this issue and was informed there was an issue in FloEFD, so we decided to use the result from JavaFoil for our airfoil. 4. JavaFoil We used JavaFoil as a substitution for FloEFD, which was not working for our team. We used this tool to search for high-life airfoils in addition to utilizing it to perform our aerodynamic characterization testing. 5. Mechanica We did not experience any issues with this software tool. 6. Creo Elements 11 One member was not able to use the PIM Installer to validate his license for Creo during the National Challenge. We contacted PTC Support regarding this issue. 1.5 Impact on STEM Most team members had prior interest in science, technology, engineering, or math, but participating in the Real World Design Challenge has deepened and broadened that interest for all members. Many of us signed up for the team wanting to fulfill one specific role, but we came to appreciate many different aspects of the challenge instead. For example, a member who was very interested in dealing with the mathematical components of the challenge realized that he also had an interest in designing and engineering. Team members come from a variety of backgrounds; some from families of engineers while others are the only member of their family interested in STEM. The Real World Design Challenge has had a profound impact on the potential career paths of our team members; all of our team members are considering rigorous careers with applications to STEM fields: Athena would like to become a software engineer. Rick is going to pursue chemical engineering. Devin is going to attend Westpoint to become a Navy SEAL. Courtney would like to become a systems engineer. Jacob wants to work as an orthopedic surgeon. Ian would like to eventually work in some engineering discipline. Alexis wants to become a pediatric oncologist. Our team is comprised of very self-motivated, determined, and ambitious students. These qualities have served us well when applied to school activities, and our experience as participants in the Real World Design Challenge has significantly contributed to our drive and determination. All of our members are involved in Advanced Placement (AP) courses of some sort, many revolving around math and science courses. Other members are eager to pursue these rigorous courses in fields of particular interest to them, and are currently involved in a plethora of honors and 12 advanced courses across all subjects. We strive to challenge ourselves and become well-rounded individuals by exploring a variety of difficult curricula, believing that those who excel in STEM are apt at balancing their roles as both visionaries and technicians. Unfortunately, engineering and related disciplines are often perceived as cold and calculating. While calculations are certainly integral to project development, STEM fields are in no way cold. We consider ourselves fortunate to have now had the experience of working on such a large scale project, where it is truly beautiful to watch all the components of the project come together to form a coherent and successful system. A direct result of participation as competitors in the Real World Design Challenge, team members have been inspired to become involved in other extracurricular activities related to science, technology, engineering, math, and critical thinking globally. These include First Lego League, First Robotics, CyberPatriot, Odyssey of the Mind, and the Stock Market Game. Several members also regularly dedicate their free time to learning programming languages, graphical design, and computer animation. 13 2. Document the System Design 2.1 Conceptual, Preliminary, and Detailed Design 2.1.1 Conceptual Design (Many Solution Candidates) Our first step in the conceptual design phase was to research what the mission would have to complete and what our constraints would be. To gain this understanding, we thoroughly read the Challenge Statement, FAA Technical Readiness Criteria, FAA rules for public sUAS Operation in the National Airspace System, and the Mission Planning Flight Guidelines. We also watched the Challenge Introduction webinar to gain an overview of expectations and work flow for the National Challenge. We approached the second step of the conceptual design phase by conducting research. We examined the definition of an unmanned aircraft, typical range and fuel types, sources of power, propulsion and retrieval systems, and other critical design factors. We looked specifically for aircraft that would fit within our design constraints due to the fact that our design may only weigh up to 55 pounds. Examining models that are on the market today helped us to understand what market expectations for UAVs exist, which assisted us in developing a competitive product. We learned quite a lot from our research, and these lessons greatly impacted the development of our solution at the State level, which we built upon and refined for the National Challenge. However, we made sure we did not rush directly into a detailed design based off of our initial observations. This resolution allowed us to make modifications to our project with ease as new announcements and changes to the challenge occurred. Our initial conceptual design was influenced greatly by the following research into existing concepts and models on the market, which taught us much about what a welldesigned UAV should be able to accomplish with a specific purpose, budget, and other resources in mind; 14 We began our research of existing models by looking at the RQ-21 Integrator that is currently being developed by Insitu. One of our mentors, Matthew Del Buono, works on this project as a software engineer, so we were fortunate to have a resource very familiar with the development of unmanned aircraft for reconnaissance missions. We discovered that this aircraft features a very interesting propulsion and retrieval system, one that propels the aircraft very effectively and is able to automatically recover it. The autonomy provided by these measures help to reduce over mission duration for the human operators, thus making missions more cost effective. This craft also features excellent payload capacity. While the RQ-21 weighs far more than 55 pounds, what we learned from it assisted us later on when we had to make a sensor payload and propulsion system selection. 15 We also came across the TU-150, pictured above, when doing our research. This UAV is notable for combining the capabilities of a helicopter with a fixed-wing aircraft. As a result of this design, the TU-150 is capable of completing a variety of missions across many different environments. From this, we recognized that we wanted to design an aircraft that was dynamic enough to successfully complete missions in plain, forested, and mountainous environments such as those at Philmont Ranch, per the challenge. 16 One idea we had entertained as a team for quite some time has been that of including solar panels on our design in hopes of making it more environmentally friendly. We recognized that something along the lines of the UAV pictured above, the X-48C, would provide optimal surface area to implement this idea. However, we later discovered that the surface area required would make the aircraft much too heavy and the power required to support the aircraft could be easily provided by batteries and would exceed the power generated by the solar panels. 17 Aircrafts that have implemented the solar panel concept, such as the NASA Helios depicted above, are unable to complete tactical reconnaissance missions such as the one the challenge prompt requires of us; another reason why we ruled this prospect out in the conceptual design phase. 18 The team also considered developing a UAS, an unmanned system consisting of several UAVs, rather than simply a single UAV. We considered using a number of microcosm UAVs to achieve this, and began to do research on what developing a micro aircraft entails. We discovered that Aerovironment is a leader in this field, and that they have several tiers of aircraft that weigh just fractions of a pound. These four tiers are referred to as the “Wasp” generation (pictured first above), and some are even manufactured to resemble flying insects or birds. Other products are slightly heavier, such as the RQ-11 Raven pictured second. While we found the micro UAV concept fascinating, we quickly realized that such small aircrafts would never be able to support the sensor payloads we would need to complete our mission. The team focused on developing a well-rounded conceptual idea of what we would like to design during this phase. Through our research, we were able to compile a list of different existing aircrafts and learn from those currently out on the market. We narrowed down these ideas into several potential solutions that we carried forth into the preliminary design phase to flesh out further. Once we had a good concept of what we wanted to accomplish, we began to examine potential airfoils in search of one that would provide excellent lift for our UAV. Keeping in mind what we learned from this research, our next step was to read the Sensor Payload Selection Guidelines document and to select a few sensor payloads 19 from the Sensor Payload Catalog in order to analyze the pros and cons of using each in our conceptualized design. X1000 normal view angle (degrees) zoom roll / pitch (deg) Slew (deg/sec) cost X2000 X3000 X4000 X5000 40 80 55 64 60 1 30 50 $8,000.00 2 85 100 $25,000.00 10 80 200 $38,000.00 16 85 200 $42,000.00 30 70 250 $75,000.00 tan view angle/2 max alt for conf – wide (feet) tan zoom view angle /2 max alt for conf – zoom (ft) 0.364 302 0.839 131 0.521 211 0.625 176 0.577 190 0.364 302 0.364 302 0.048 2,285 0.035 3,143 0.017 6,288 opt alt for scan – wide (ft) max alt for scan – zoom (ft) 1,407 1,407 610 1,407 984 10,659 819 14,662 887 29,332 The above table demonstrates how we analyzed the sensor payloads provided as options in the catalog. We decided that the X3000 was the most efficient single payload, and we began to consider the idea of utilizing multiple sensor payloads on our design. In our State solution, we utilized three X1000s for the purpose of detection and a single X3000 for identifying the object detected as the child we were searching for. We wanted to minimize our objective function further for the National Challenge, so this would involve decreasing cost as well as the duration of the reconnaissance mission. There are two main cost penalties associated with utilizing multiple sensor payloads on one UAV. The first of these is the initial purchase price of the sensor itself, and the second is the cost of required additional UAV components per payload. For example, the Configurator spreadsheet requires the purchase of one Video Datalink UAV Transmitter ($200) and one Onboard Video Receiver ($600) per sensor payload. If we intended to use multiple sensor payloads on a single UAV, this would get extremely 20 expensive very quickly. As a result, we recognized that we needed to use as few sensors as possible while still retaining optimal mission efficiency. 21 Our fourth step was to consider how we would like our conceptualized design to ultimately conduct missions. We reviewed the Mission Flight Planning guidelines and began to think about potential search patterns and sensor payload distributions across the aircraft to maximize camera footprint and thus minimize mission duration. This pattern would depend greatly on how many UAVs we decided to use, however, so we resolved to develop a spreadsheet to calculate the objective function output of using a number of UAVs (1-8) with a variety of sensor combinations in the three portions of the given search area (tall trees, short trees, no trees). This allowed us to consider the relative objective function and total cost over 50 missions, as yielded by these combinations. As a result of these considerations, we were left with a variety of potential candidate solutions. We left the conceptual design phase debating whether or not to use one or multiple sensor payloads and, if the latter option, how many. We quickly recognized that the inclusion of multiple payloads might require us to utilize a more powerful and heavier propulsion system, while fewer sensors could be supported by a less powerful propulsion system. 2.1.2 Preliminary Design (Few Solution Candidates) To prepare for the preliminary design phase, we watched the Aviation Design webinar as a team and began to utilize the FY13 Aviation National Challenge Toolset. Our first step in the preliminary design phase was to implement what we had learned regarding each sensor payload into our considerations. We recognized that our sensor selection would impact the rest of the design, including propulsion system selection and mission planning, so selecting our sensors was our first step. All sensor models feature a resolution of 640x480. As it requires 4 pixels for object detection, we noticed that the wider view angles offered in the more expensive models actually require the UAV to fly at a lower altitude, which yields a smaller camera footprint. Our first priority when choosing the sensor payload was to obtain as much camera footprint as possible within the maximum detection distance circle. For the State 22 challenge, we recognized that combining three X1000 sensor payloads would be a cost effective way to dramatically increase the camera footprint. For identifying the object -in the issued challenge, a small child -- the X3000 was adequate because of its 10x telescopic lens. The idea was to let the three X1000 tilted up so they could detect the object forward. As the object was detected, the X3000 then identified the object. However, we wanted to optimize our design for the National challenge. This would involve minimizing both mission time and cost. From the analysis of camera configuration, we realized that using multiple sensor payloads over the tall-tree area does not help reduce the search time. To drastically minimize mission duration, we recognized that we would have to use more than one UAV in our unmanned aircraft system (UAS). With this in mind, we decided that we could not use the same sensor payload combinations as we had previously, as that payload combination works well only over the no-tree area and would be too expensive to yield a low objective function. Though we had a general idea that using more UAVs might yield a lower value of objective function, we needed a quantitative analysis to find how many UAVs could theoretically yield the best result. The first quantitative analysis we performed was to estimate the search time for a single UAV in all three zones. The search time is determined by two factors; air speed and scanning width. Due to the required 0.5 seconds for detecting an object and 5 seconds for identifying an object, the air speed and scanning width are not independent factors. As illustrated by the graph below, when the width of camera footprint is larger than the diameter of the maximum detection circle, the maximum scanning with Ws is related to air speed v and the diameter D of the maximum detection circle as: 23 Detection and Identification 𝑤𝑠 = √𝐷2 − (5.5𝑣)2 Detection Only 𝑤𝑠 = √𝐷2 − (0.5𝑣)2 With a formula to calculate the scanning width, we were able to find the best scanning widths for the chosen sensor payloads in each zone. After carrying out some calculations, we realized that reasonable scanning width can be obtained for detection and identification preformed in sequence only at a no-tree zone. Over the short-tree zone and tall-tree zone, (especially over the tall-tree zone) scanning width for detection and identification preformed in sequence is rather small and thus increases search time dramatically. To achieve an acceptable search time, we decided to use the turn-around identification strategy over the short-tree and tall-tree zones. Over the No-Tree zone, adding sensor payload can effectively widen the scanning width. We decided to combine X1000 and X3000 sensor payloads for searching the NoTree Zone. At the altitude 680 AGL, this sensor payloads combination has a scanning width of 1182 ft. Over the short-tree zone, we figured out the best navigation altitude is 794 ft AGL where the Max Detection Distance Circle for X1000 overlaps with the circle with short-tree zone Line of Sight. For the combined sensor payloads of X1000 and X3000, at 80 mph, it has a scanning width of 914 ft if the turn-around identification strategy is used. We also considered the case that only X3000 sensor payload would be used. With the field of view of X3000 adjusted to 41.5/31.125 degrees such that the camera footprint 24 rectangle touch the Max Detection Distance Circle, the sensor payload could have a scanning width of 624 ft. Over the tall tree area, the search is severely limited by the 15-degree Line of Sight. We recognized that it is preferable to have a sensor payload with narrower field of view and navigate at a higher altitude. With X3000 sensor payload zooming to 30/22.5 degrees field of view from the altitude of 1000 AGL, the effective scanning width at 80 mph is about 532 ft if the turn-around identification strategy is used. Knowing the scanning width, the next step was to estimate the search time. Though there is a Mission Planning Excel Worksheet provided in the Design Kit, it is not suitable for estimation as it requires almost all the design variables of the whole UAS which we wouldn’t have at the preliminary design phase. We decided to develop our own Excel Worksheet to estimate the search time in each zone. Besides the scanning width and air speed, the search pattern is another factor that has great impact on the search time. For example, comparing the two search pattern illustrated below, the Ray-SearchPattern will need twice the time needed by the Shell-Search-Pattern because there is overlap in the center when searching with the Ray-Search-Pattern. Ray-Search-Pattern Shell-Search-Pattern 25 With the Shell-Search-Pattern, the total travel distance can be estimated (time needed for turn-around is neglected) as 𝑁 ∑ 𝜃 ∙ (𝑟 + 𝑖=0 𝑊 + 𝑖 ∙ 𝑊) 2 , where N is the integer no less than (R-r)/W. The search time can then be calculated by dividing the total travel distance by the air speed. Shown below is a screen capture of a spreadsheet we developed for estimating the search time with various air speeds. Once we were able to estimate the search time, we started to consider the effect to the objective function when adding more UAVs. Shown below is a screen capture of a spreadsheet that we developed to calculate initial cost, operational cost per hour, search time (hrs), total operation time (search time + 8 hours, rounded to the nearest hour), total cost of 50 missions, and the objective function output. We then charted the relative objective function vs. number of UAVs to verify the worthiness to employ more UAVs: 26 Relative Objective Function Value 1.2 1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 Number of UAVs The chart demonstrated to us that the more UAVs we used, generally, the lower the objective function was despite the increase in cost. However, the effect of lowering objective function diminished quickly when there were more than four UAVs used. Furthermore, we noticed that the Mission Planning spreadsheets provided in the National Challenge Toolset only allowed for up to 4 UAVs to be used in the UAS. Still, this portion of our preliminary design was meant to determine how many UAVs we should use to reduce flight time, and found that the answer was basically as many as we can feasibly support. Previously, we had utilized three X1000s for detection and one X3000 for identification. With the information above in mind, we examined the sensor payload specs to see if there might be a way that the X3000 could fulfill both roles, as the X1000 certainly is not adequate for both. The X3000 sensor payload features continuous zoom between 5 and 55 degrees, and we realized that we would have to zoom out to approximately 40 degrees to detect the object in the two zones with limited line of sight. 27 For searching the tall trees zone, we decided to use only this sensor payload on two out of our four UAVs because the addition of an X1000 payload would not increase the scanning width to reduce the search time, but adding the cost of that sensor. We had to ensure that the aircraft we would be designing was large enough to support this payload, so our next step was to estimate gross weight of the combined payload, which were 2.6 pounds for the design with two sensors (X1000 & X3000) and 2.1 for the one utilizing only the X3000. This left us quite a lot of room under the 55 pounds maximum weight limit given in the issued design constraints, giving us the ability to later choose from many potential propulsion systems. We knew that we would need a high lift airfoil for the low stall speed and smaller wing planform area. Unfortunately, a high-lift airfoil is generally accompanied by high drag, which can be a concern when it comes to fuel efficiency. Even despite this tradeoff, the constraint outlined above reminded us that we absolutely would have to find an airfoil with high lift. We found high-lift, low Reynolds number airfoils by searching the UIUC database and the three volumes of Summary of Low-Speed Airfoil Data. We then tested the selected airfoils with JavaFoil to find their aerodynamic characteristics. We evaluated the following airfoils with a preliminary run of the provided MathCAD Performance worksheet: 28 S1223 S2027 29 SD7037 SD7062 We found that S1223 was the airfoil with the highest Cl max (>2) when the data of coefficient of lift was observed visually. However, the Performance MathCAD worksheet fit the data with a curve having a much lower maximum. The airfoil SD7062 has a Clmax above 1.8 which was an adequate fit for the needed lift. The following charts illustrated two important aerodynamic characteristics of SD7062: 30 Lift Coefficient vs. Drag Coefficient Lift Coefficient vs. Angle of Attack In fact, we found that by using the SD7062, the wing planform area could be reduced to 600 in2. 31 At this point, we input our sensor payload, propulsion system, and additional component selections into the Configurator Excel worksheet to examine costs. Reviewing the following output values for our two designs, helped us to evaluate the efficiency of our aircraft: Design A Design B Fuel Tank $12.50 $12.50 Batteries $35 $35 Electrical Wiring $5 $5 Wing $409.45 $409.45 Horizontal Tail $76.54 $76.54 Vertical Tail $27.09 $27.09 Fuselage $1164.25 $1164.25 Sensor Payload(s) $46000 $38000 Propulsion System $545 $545 Video Datalink UAV $400 $200 $300 $300 Flight Control System $2000 $2000 Total cost when without $50,974.82 $42,774.82 Petro Fuel $5 $5 Total cost with fuel $50,979.82 $42,779.82 Transmitter Command Datalink UAV Transceiver fuel We continued testing by running a preliminary performance analysis to ensure the viability of our design up to that point. We reviewed the Mission Flight Planning Guidelines and then tested the endurance and total search time of our UAV, two very crucial factors to our mission plan. We evaluated our objective function value output, as given in the Mission Planning Excel sheet and Mission Analysis MathCAD worksheet. 2.1.3 Detailed Design (One Candidate Solution Refined) Our goal for the detailed design phase was refine and optimize the design that emerged successfully from the preliminary design phase. To accomplish this, we first watched the 32 Aviation Design Process (Part II) webinar as a team to gain perspective. Then, we had to identify our selections for all the components required to assemble the UAV. These included our sensor payloads, video datalink transceiver/video recorder, control datalink transceiver, associated antennae, propulsion system, required batteries for all electronics, and the fuel tank. We ensured these components were input into the Configurator successfully, as these cost figures contributed significantly to the final revisions of our business plan, which had to incorporate—among other components—a working market assessment and amortization of incurred costs, including initial and iterative operation throughout the 50 missions. After identifying all selections, we assembled all the Creo Part files for the components and sized our fuselage accordingly to handle this payload. We then placed all components inside of the fuselage. When these tasks had been completed, we used the Configurator spreadsheet to produce weight and balance analysis for our UAV. We then used JavaFoil to analyze our airfoil selection, SD7062, and input the results of this airfoil analysis into the provided AeroData document, which yielded the aerodynamic coefficient data. We also performed a zero-lift drag estimate analysis for the UAV using the Performance Mathcad worksheet. We found that we could reduce the planform area from 600 in2 to 540 in2, so we did so to reduce weight and drag, effectively increasing efficiency. One constraint given in the challenge was that the UAV had to be capable of flying over a 50 feet high obstacle within 300 feet after take-off. This means that we should have a reasonably powerful propulsion system as well as a high-lift airfoil. We had previously used the GL25 engine to serve this purpose as well as minimize mission duration overall. At the end of preliminary design, we had an UAS consisting of four UAVs powered by GL25 propulsion system that could finish search under 21 minutes. This relative short search time lured us to consider the possibility of utilizing electric propulsion system which could make the fuselage more streamlined and possibly reduced the weight of the UAV. We found E-20 from the provided list of electric propulsion systems which had equivalent power output as GL25 and a much smaller 33 size/weight. We went ahead to redesign the fuselage and found the reduced weight in fuselage can offset the weight of added batteries. With the new design, all four of the UAVs are under 35 lbs and have more 30% fuel remained after the mission. The specifications of our UAVs, which incorporate two designs, are: 2 Wing Planform Area (in ) Wing MAC (in) Wmtow (lbf) Wbattery (lbf) Alphastall (deg) Maximum Lift Coefficient Vmin at 8000 ft MSL(mph) Engine Max Power (hp) Power Loading (lbf/hp) Propeller Efficiency Static Thrust (lbf) Engine(motor) Efficiency Wing Loading (lbf/ft2) Distance to Clear 50ft Obstacle Design 1 (X1000 + X3000) 540 8.25 34.96 3.70 12.198 1.837 50.253 2.414 14.483 0.8 13 0.96 9.3227 189.995 Design 2 (X3000 only) 540 8.25 34.41 3.70 12.198 1.837 49.856 2.414 14.255 0.8 13 0.96 9.176 184.492 2.1.4 Describe Lessons Learned We learned quite a lot about the engineering design process in each design phase. In the conceptual design phase, most of our activities involved research. Team members examined other unmanned aircrafts that are used in the real world to find models efficient enough to provide us with an idea of the kind of UAV we would like to develop. Based off of what we had learned, we then began to search for airfoils and constructed basic designs that incorporated the concepts we had discovered. For the preliminary design, we continued our research and began learning how to flesh out the designs with the provided worksheets and computer-aided design software. We first identified the most cost-effective combination of sensor payloads that would ensure an adequate camera while and minimizing cost and time. Next, we created the UAV model that could contain all the needed components in the fuselage. We searched for 34 airfoils that would provide high lift for our aircraft, and then started to test each option to find which would be most suitable for our design. It was here that we began to significantly consider the performance viability of our aircraft. We learned quite a lot about cost benefit analyses, as we had to perform a performance analysis on each design, which determined our selection of airfoil and the wing configuration to move onto the detailed design phase. Finally, we attempted to perfect our chosen design in the detailed phase. Members were more experienced at this point, and used our learned cost-benefit analysis and research skills to work on the business case and mission planning revolving around our detailed design. We also made a final propulsion system selection and focused on perfecting our UAV and conducting mission analysis to ensure efficiency by minimizing our objective function as much as possible. 2.1.5 Describe project plan updates and modifications We took an agile development approach with our project, something that we had learned about from one of our mentors who works as a software engineer and is also a Scrum practitioner. Scrum is an iterative and incremental agile development framework for managing product development. It focuses on "a flexible, holistic product development strategy where a development team works as a unit to reach a common goal" as opposed to a "traditional, sequential approach”. Essentially, we resolved issues as they arose through the process of iterative and incremental development throughout the project. This ensured that time we used working on the project was very effective as we would not have to face loads of problems at the end of the design phase because we had addressed these issues and modified our design as they arose. This gave us flexibility when updates to the RWDC Aviation Design Kit or Worksheets were modified, for example. Our environment as students of an online, virtual school helped us significantly. We are all accustomed to having to take the responsibility of meeting deadlines, and tools that we need to do that are at our fingertips. Our Adobe Connect room provides us with a 35 modular version of Dropbox, called the “Sharepod”, where we could share files quickly with each other. We could also text and voice chat in the room. Engineering requires that all parties involved communicate well and specifically to begin with, but because we did not meet physically even once to complete this challenge, we had to communicate exceptionally well with each other and our unique situation as online collaborators only helped to foster these skills. Each week during all design phases, and the preliminary phase in particular, we set goals to accomplish for the next week. By keeping up with these and organizing our documents using Dropbox, the Sharepod, and Windchill, we were able to successfully complete each benchmark on time. 2.2 Detail the Aerodynamic Characterization We used the provided Performance MathCAD worksheet to analyze our aerodynamic characterization. Our geometric input into the sheet was our wing planform area, wing aspect ratio, UAV wetted area (without wing), and wing MAC incidence to fuse axis. To obtain the aerodynamic data needed for the Performance MathCAD worksheet, we first preformed CFD analysis using FloEFD as demonstrated in the webinar video. Unfortunately, the result obtained deviated significantly from both the wing-tunnel experiment result as well as JavaFoil. We contacted RWDC support and were informed that there was issue in FloEFD and we should proceed with the calculated result from JavaFoil. The input values of our aerodynamic data for SD7062 airfoil are as follows: 36 This table displays the coefficient of lift, drag, and moment experienced by each degree section of our wing. The analysis results for our aerodynamic characterization are: 37 Cl Having a high coefficient of lift was important to us to ensure that we would meet the constraint that demands we be able to clear an obstacle 50 feet tall within 300 feet after takeoff, and is also necessary to ensure adequate altitude over each zone. Essentially, the higher the coefficient of lift the better the wing is working. Cd The more drag, the more thrust is required to keep the UAV flying. Our coefficient of drag was important because we wanted to minimize drag on our aircraft as much as possible, which is why we were excited to reduce our planform area from 600in2 to 540in2. 38 Cm Coefficient of moment describes our angle of attack, which we wanted to optimize for our design to ensure minimal drag. Our calculations to find our minimum airspeed at maximum takeoff weight are as follows: The minimum velocity is only slightly over 50 mph which empowers our UAVs to make tight turn when needed. 39 Wing loading is the aircraft weight per unit of wing area. A high wing loading equates to a high minimum speed. Our result as output by the provided Performance Mathcad sheet: Aircraft must be trimmed for flight by resolving unbalanced pitching moments by balancing tail loads. This is crucial because a design that is not well balanced is penalized by a high trim drag from the horizontal tail. The following is our review of balancing tail loads impact on lift and drag: The most efficient airspeed can be found at the maximum velocity times lift divided by drag. We changed the altitude, flight weight, center of gravity, and airspeed in the provided Performance Mathcad sheet to analyze how the best cruise speed varies for our configuration versus altitude. We input the following details… Velocity: 75 mph Altitude: 8000 ft Flight weight: 35 lbf Flight Center of Gravity: 23.124 in …this allowed us to find our most efficient airspeed: One constraint issued as a part of the National challenge was that the UAV designs must be able to clear a 50 foot tall obstacle within 300 feet after takeoff. To verify that 40 our two designs could accomplish this, we analyzed the following result from the provided Performance Mathcad sheet: This result confirmed that we had met the requirement of that constraint. Next, we ran a cycled, iterative set of loiter speed calculations until we were able to find the ground speed that maximizes lift over drag: This speed, 77 mph, is close to the maximum allowed speed 80 mph which our UAVs will be flying at most of time. 2.3 Selection of System Components 2.3.1 Propulsion System We chose the E-20 electric engine as our propulsion system during the detailed design phase. We felt that this selection as most appropriate as the power output of 1800 watts generates enough thrust to clear an obstacle 50 feet high within 300 feet after takeoff as well as maintain an appropriate speed and altitude over each zone of the Philmont ranch. As we have learned in previous years as competitors in the Real World Design Challenge, electric engines generally tend to be slower than diesel alternatives. With this in mind, we had previously used the GL25 engine. With the introduction of the three distinct zones (tall trees, short trees, no trees), however, we had to change our search pattern to ensure that all of our UAVs had adequate time to detect and identify objects throughout the zones in search of the child. For half of our UAVs, this meant detecting and immediately zooming in to identify, while for the other half it meant detecting an object and then identifying it after turning around. Our search pattern is illustrated below for your reference: 41 Given the line of sight limitations—30 degrees from vertical in the short trees zone and 15 degrees from vertical in the tall trees zones—in addition to our sensor payload selection (2/4 designs use one X3000 for both detection and identification while the other 2/4 designs use one X1000 for detection and one X3000 for identification), we were more concerned with overall flight efficiency over just speed. For us, this meant ensuring that our sensor payload selection and flight path were optimal, as well as ensuring that there was minimal—if any at all—camera overlap near the edges of the zones. Because speed itself was no longer our first priority, the E-20 propulsion system suited our needs best. 2.3.2 Sensor Payload Selection Initially, we considered using three X1000s for detection and one X3000 for identification. Our thought with this configuration was that that using the three detection payloads would help to maximize our camera footprint and thus speed up the mission. However, because each sensor is so expensive, we examined the sensor payload specs to see if there might be a way that the X3000 could fulfill both roles, as the X1000 certainly is not adequate by itself for identification purposes. The X3000 sensor payload features continuous zoom between 5 and 55 degrees, and we realized that we would 42 have to zoom out to approximately 40 degrees to identify the object in the two zones with limited line of sight. We decided to use only this single X3000 sensor payload on two out of our four UAVs. These two would search the tall trees area, where the addition of an X1000 payload would not increase the scanning width at all. In the zones with no-trees and short trees, the other two UAVs are equipped with one X1000 and one X3000 because we found that the addition of the X1000 could increase the scanning width to speed up the search significantly to justify the $8000 cost of that sensor. Design A, 2 UAVs search the no trees area Equipped with the X1000 and X3000 and move to search the short trees. payloads. Design B, 2 UAVs search the tall trees zone. Equipped only with an X3000 payload. 2.3.3 Ground Station Equipment Selection With our design defined and our propulsion system and sensor payload selections out of the way, we then went through the Configurator spreadsheet to according to the provided ground station requirements (detailed below in the table) to pick the necessary Ground Station equipment that we would need to suit the needs of our UAS. Our selections are as follows: 43 Ground Station Options Per Item Cost Component Required Quantity Quantity Total 1 per UAV 1 per UAV 4 4 $800 $6000 1 per set of 4 sensor payloads $300.00 1 per UAV 2 $24000 4 $1200 $400.00 1 per sensor payload 6 $2400 1 1 $14000 $12712.73 $61,112.73 Safety Pilot Flight Box Operational Pilot Workstation Computer $200.00 $1,500.00 Sensor Payload Workstation Computer - Version B $12,000.00 Command Datalink Ground Transceiver Video Datalink Ground Receiver Shelter/Trailer - Fleet Launch Catapult/Snag Line Ground Station Total $14,000.00 1 per sUAS $12,712.73 1 per sUAS In addition to physical equipment, we also had to determine our “per-hour” cost. We did this by following the personnel requirements listed in the Configurator spreadsheet, and went about selecting the appropriate personnel for our UAS. We found that we would not need any “data analysts” due to our utilization of computer software. Our personnel selections are as follows: Operational Personnel Resource Payload Operator Ground Search Personnel Range Safety/ Aircraft Launch & Recovery/ Maintenance Safety Pilot Operational Pilot Personnel Total Resource Cost Per Hour Number of Positions Required $150.00 $0.00 2 3 $175.00 1 $100.00 $150.00 $1,475.00 4 4 44 2.3.4 Additional UAV Components In addition to determining our ground station equipment and personnel selections, the Configuration also required the selection of some additional UAV components relative to each design. For our Design A, which features two sensor payloads, our selections are: Component Video Datalink UAV Transmitter Command Datalink UAV Tranceiver Flight Control System Total Additions Additional UAV Components for Design A Fuselage Moment Weight Per Item Required Station (inch(lbs) Cost Power (inches) lbs) (Watts) 30.00 3.0 0.05 $200.00 0.4 53.00 5.3 0.10 $300.00 0.3 50.00 5.0 0.10 $2,000.00 0.1 44.33 13.3 0.30 $2,700.00 1.20 Required Quantity Quantity Up to 1 per sensor payload Up to 1 per UAV 1 per UAV 2 1 1 We had the option of including an onboard video receiver, as can be seen above, but the data recorder requires you to land, unload data and fly back out - time penalty is not justified by the cost reduction. The Video Datalink Transmitter and Transceivers were necessary to fulfill the requirement of communication between the UAS in flight and the ground station, and our selection of the Flight Control System was required by the Configurator spreadsheet. For our Design B (which features only one sensor payload) our selections—made by following the same selection criteria—are as follows: Component Video Datalink UAV Transmitter Command Datalink UAV Tranceiver Flight Control System Total Additions Fuselage Station (inches) 30.00 Additional UAV Components for Design B Moment Weight Per Item Required (inch(lbs) Cost Power lbs) (Watts) 1.5 0.05 $200.00 0.4 53.00 5.3 0.10 $300.00 0.3 50.00 5.0 0.10 $2,000.00 0.1 47.20 11.8 0.25 $2,500.00 0.80 Required Quantity Quantity Up to 1 per sensor payload Up to 1 per UAV 1 1 per UAV 1 1 45 2.4 Aircraft Geometric Details 2.4.1 Wing Configuration We chose the SD7062 airfoil given its high-lift properties that we needed. We found that by using the SD7062, the wing planform area could be reduced from 600 in 2 to 540 in2. We input the following into the provided Wing Definition Mathcad sheet to calculate wing parameters, generate a plot of the wing planform, and send root and tip section coordinates to output data files: Our design inputs, taken from airfoil analysis spreadsheets we developed, output the following: We used this information to define our wing and generate a plot of the wing planform, where the aerodynamic center is denoted. We then used this plot and the output wing coordinates, also calculated in the Mathcad sheet, to create our wing in Creo Elements. We imported the two generated coordinate files for our root and tip into Creo to create point references, and then used the features of Creo itself to create solid wing geometry. 46 2.4.2 Tail Configuration With a wing defined, the next step was to define our tail. We defined two sections in our tail configuration; the vertical and horizontal tails. To calculate tail specifications, we first had to input wing details (planform area, span, mean aerodynamic chord, aerodynamic center) into the Vertical Tail Definition Mathcad sheet. We also input the following details: The resultant calculations sized the tail arm at 32.481 inches, the tail volume coefficient as 0.02, planform area as 21.854 in2, aspect ratio 3.5, taper ratio 0.5, and a sweep of 15 degrees. The vertical tail design outputs are: Like when we were defining our wing, this sheet also generated coordinate files and a plot of our planform that we used to create our CAD model. Our next step was to define our horizontal tail. We input the same wing and fuselage details as listed above, and the output calculations defined an aspect ratio of 4, taper ratio of 0.7, sweep angle of 15 degrees, and declared dihedral, incidence, and washout angles at 0, and planform area of 70.754 in2. The design outputs are as follows: 47 With this information and the generated coordinate files, we were finally able to construct all the components of our tail in Creo. 2.4.3 Fuselage For both UAV designs, we used the same fuselage which is 60 inches long with the widest cross-section being a 5 in. x 5.5 in. ellipse. We chose this size because not only is it capable of supporting our current propulsion system, it can also support a larger electric engine or more batteries for further range. This size was also sufficient to support additional components, such as sensors and wiring. Using the same fuselage gave us to flexibility to add or remove the X1000 sensor payload based on the mission requirement. 48 The equipment layout is shown in the picture below: 2.5 System and Operational Considerations The UAS with four UAVs we have designed is targeted to reach lowest objective function value while maintain the total cost under one million dollars. Though based on our analysis, adding more UAVs can reduce the search time and lower the objective function, it also adds complexity in mission planning. We have found it was difficult to plan mission for four UAVs with balanced search load. As discussed in our business plan later, the added cost may not appeal to the customer as the effect in the timesaving is not significant. If a much larger area is to be searched, we would reconsider the selection of propulsion system. The choice of E-20 electric engine is geared for the goal set for the National Challenge. Using GL-25 gas engine will be more practical in general business practice. 49 2.6 Component and Complete Flight Vehicle Weight and Balance Design A Component Batteries Fuselage Station (inches) Moment Weight (inch-lbs) 45 166.5 24 Electrical Wiring Wing Design B Moment Weight (lbs) Fuselage Station (inches) (inch-lbs) (lbs) 3.7 45 166.5 3.7 0.5 24 12 24.87 188 56 Horizontal Tail 12 7.56 24.87 1.32 56 73.9 57 Vertical Tail 0.5 188 7.56 1.32 73.9 0.47 57 26.8 0.47 26.8 Fuselage 15.34 267.1 17.41 15.34 267.1 17.41 Total Airframe Sensor Payload Model 23.72 734.3 30.96 23.72 734.3 30.96 X1000 19 9.5 0.5 X3000 23 48.3 2.1 23 48.3 2.1 Total Sensor Payload Propulsion Model 22.23 57.8 2.6 22.23 57.8 2.1 E-20 2.75 3 1.1 2.75 3 1.1 2.75 3 1.1 2.75 3 1.1 30 3 0.05 30 3 0.05 Command Datalink UAV Transceiver 53 5.3 0.1 53 5.3 0.1 Flight Control System 50 5 0.1 50 5 0.1 44.33 13.3 0.3 44.33 13.3 0.3 23.12 808.4 34.96 23.17 797.3 34.41 Total Electric Propulsion Additional Component Video Datalink UAV Transmitter Total Additions At MaxTakeoff Weight 2.7 Maneuver Analysis The performance analysis result shows that the distance to clear 50 ft obstacle are 190.0 ft and 184.5 ft respectively for both UAV designs we have. In our mission planning for all of the four UAVs, the highest rate of climb is about 740 fpm. With E-20 electric engine, the needed power output is about 50% of what E-20 can offer. 50 Way Point A Ground Speed (mph) Rate of Climb/ Decent (fpm) 80 80 740 740 Distance Traveled (miles) 0 1.226 Elapsed Time (minutes) 0 0.9195 Altitude (feet) 8000 8680.4 Percent Power 100 50.643 Percent Petro Remaining Percent Battery Remaining 100 100 100 93.082 Therefore, our propulsion selection is very capable of accomplishing the mission. Regarding to the turn-around at the edges of the zone, we adjusted the speed to make sure no warnings logged in the mission calculation output. As stated in the webinar, the minimum turn-around radius was calculated with angle of bank capped at 30 degrees angle of bank. However, in our analysis which will be discussed in later section, it is possible to have greater angle of bank at high speed. 2.8 CAD Models Design A: with X1000 & X3000 Sensor Payloads 51 Design B: with only X3000 sensor payload 2.9 Three View of Final Design Top View: 52 Front View: Side View: 53 Vehicle Flight Dimensions: 54 3. Mission Planning 3.1 Search Pattern As stated in the preliminary design section, we found the shell-search-pattern as illustrated below is an efficient way to search through each zone. We decided to let two UAVs with only the X3000 sensor payload to search tall-tree area first and then move to search the short-tree area. Meanwhile, the other two UAVs— equipped with both X1000 and X3000 sensor payloads—search the no-tree area first and then search the short-area. Over the Tall-tree and Short-tree areas, after detecting the object, the UAV turns around to identify the object. Over the No-tree area, after the UAV detects the object, the X3000 sensor payload zooms in immediately to identify the object. For using the turn-around identification strategy, it is necessary to estimate the time needed for turn-around. In the later “System Detection and Identification” section, the time needed for turn-around will be discussed in detail. The graph below depicts the mission path of our UAVs through the three zones, and labels each turn in the search pattern; 55 This graph, as output by the provided Mission Planning Excel spreadsheet, was a cause of concern for us as it illustrated that there may be some minimal—but still existent— uncovered area along the edge of each zone where the UAV turns. 3.2 Camera Footprint Our sensor payload selections and resultant camera footprints over each search zone are as follows: 56 No-Tree Area (with one X1000 and one X3000 sensor payloads): Altitude: 680 AGL X1000 Field of View (HFOV/VFOV): 40/30 (deg.) X3000 Field of View (HFOV/VFOV): 41.5 / 31.125 (deg.) X1000 Pointing (Roll right/Pitch up): +20/0 (deg) X3000 Pointing (Roll right/Pitch up): –20/0 (deg) Total Camera Footprint Width: 1182 (ft) Detection Area Radius: 615 ft 57 Effective Scanning Width: 1182 (ft) Short-Tree Area (with one X1000 and one X3000 sensor payloads): With one X1000 and one X3000 sensor payloads Altitude: 794 AGL X1000 Field of View (HFOV/VFOV): 40/30 (deg.) X3000 Field of View (HFOV/VFOV): 41.5 / 31.125 (deg.) X1000 Pointing (Roll right/Pitch up): +20/0 (deg) X3000 Pointing (Roll right/Pitch up): –20/0 (deg) Effective Scanning Width at 80 mph: 914 (ft). 58 With only one X3000 sensor payload: Altitude: 794 AGL Field of View (HFOV/VFOV): 41.5 / 31.125 (deg.) Camera Pointing (Roll right/Pitch up): 0/0 (deg) Camera Footprint Width/Length: 624/472 (ft) 59 Tall-Tree Area (with only one x3000 payload): Altitude: 1000 AGL Field of View (HFOV/VFOV): 30 / 22.5 (deg.) Camera Pointing (Roll right/Pitch up): 0/0 (deg) Camera Footprint Width/Length: 546/412 (ft) Zone 3 Line-of-sight radius: 268 ft. Effective Scanning Width at 80 mph: 532 ft. 3.3 System Detection and Identification The search time is determined by two factors; air speed and scanning width. Due to the required 0.5 seconds for detecting an object and 5 seconds for identifying an object, the air speed and scanning width are not independent factors. As illustrated by the graph below, when the width of camera footprint is larger than the diameter of the maximum detection circle, the scanning with Ws is related to air speed v and the diameter D of the maximum detection circle as: 60 Detection and Identification Detection Only 𝑤𝑠 = √𝐷2 − (5.5𝑣)2 𝑤𝑠 = √𝐷2 − (0.5𝑣)2 The red rectangles in the diagrams above represent the effective area for detection and identification (or just detection) with the maximum scanning width. As discussed in preliminary design section, we realized that reasonable scanning width can be obtained for detection and identification preformed in sequence only at a no-tree zone. Over the short-tree zone and tall-tree zone, (especially over the tall-tree zone) scanning width for detection and identification preformed in sequence is rather small and thus increases search time dramatically. To achieve an acceptable search time, we decided to use the turn-around identification strategy over the short-tree and tall-tree zones. At 80 mph (7040 ft/min), with a 30 degree angle of bank, the turn radius is 741 ft. The turn-around time is 2**741/7040 = 0.661 minute. However, at 80 mph, the UAV is capable of turning at 65 degree angle of bank which has the turn radius of only 199 ft. In this case, the turn-around time is 0.178 minute. Mathematically, the turn-radius and turn-around time can be expressed by the following equations: 𝑣2 𝑇𝑢𝑟𝑛 𝑅𝑎𝑑𝑖𝑢𝑠 𝑟 = g tan 𝛼 𝑇𝑢𝑟𝑛 − 𝑎𝑟𝑜𝑢𝑛𝑑 𝑡𝑖𝑚𝑒 𝑡 = 2𝜋𝑟 2𝜋𝑣 = 𝑣 g tan 𝛼 61 For the same air speed, the larger the angle of bank, the shorter the turn-around time. However, the angle of bank is limited because the only part of the lift is can be used to counter the weight of the aircraft For the aircraft to maintain altitude, 𝑊𝑒𝑖𝑔ℎ𝑡 = 𝐿𝑖𝑓𝑡 ∙ cos 𝛼 The stall turning speed ustall is related to vstall as 𝑢𝑠𝑡𝑎𝑙𝑙 𝐿𝑖𝑓𝑡 1 √𝐿𝑖𝑓𝑡 = =√ = 𝑣𝑠𝑡𝑎𝑙𝑙 √𝑊𝑒𝑖𝑔ℎ𝑡 𝑊𝑒𝑖𝑔ℎ𝑡 √cos 𝛼 𝑢𝑠𝑡𝑎𝑙𝑙 = 𝑣𝑠𝑡𝑎𝑙𝑙 √cos 𝛼 For a given turning speed u, the maximum angle of bank is 𝑣𝑠𝑡𝑎𝑙𝑙 √cos 𝛼𝑚𝑎𝑥 = 𝑢 𝑣𝑠𝑡𝑎𝑙𝑙 2 cos 𝛼𝑚𝑎𝑥 = ( ) 𝑢 𝑣𝑠𝑡𝑎𝑙𝑙 2 𝛼𝑚𝑎𝑥 = cos −1 ( ) 𝑢 Assuming 𝑣𝑠𝑡𝑎𝑙𝑙 = 52 𝑚𝑝ℎ, 62 The shortest turn-around time at different speed is 𝑡𝑚𝑖𝑛 = 2𝜋𝑟 2𝜋𝑢 = 𝑢 g tan 𝛼𝑚𝑎𝑥 𝑣𝑠𝑡𝑎𝑙𝑙 2 2𝜋𝑢 ( 2𝜋𝑢 𝑢 ) = = 4 4 √1 − (𝑣𝑠𝑡𝑎𝑙𝑙 ) √1 − (𝑣𝑠𝑡𝑎𝑙𝑙 ) 𝑔 𝑢 𝑢 𝑔 𝑣𝑠𝑡𝑎𝑙𝑙 2 ( 𝑢 ) The above graph indicates that the shortest turn-around time can be achieved at air speed 80 mph, which is well under 0.2 minute. 3.4 Example Mission First, we would first need to arrive at Philmont Ranch. The drive there would take us 3.5 hours each way, with .5 hours allotted for set-up and tear down. Our operational time, 63 as a result, would be 9 hours total. Our search time itself takes only 20.493 minutes. All UAVs end the search with 30% or more power remaining. An example mission with four UAVs is illustrated in details in the tables below. Basically, UAV#1 and UAV#2 search the no-tree zone first and then search the shorttree zone while UAV#3 and UAV#4 search the tall-tree zone first and then search the short-tree zone. UAV #1: Waypoints A B C D E F G H I J K L M M O P Q R UAV Position Distance Angle from from Search Search Center Center (miles) (degrees) 1.890 1.890 1.669 1.670 1.447 1.447 1.088 1.088 1.420 1.420 1.752 1.752 0.413 0.413 0.177 0.177 0.059 0.059 250 90 90 250 250 90 90 0 0 90 90 0 0 90 90 0 0 90 Segment Type (S, P) for Straight, Polar Waypoint Corner Turn Radius (feet) S P S P S P S P S P S P S P S P S P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Camera Ground Footprint Speed Width At (mph) Ground (feet) 0 1178 1178 1178 1178 1178 0 910 910 910 910 910 910 910 910 910 910 910 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 52 52 80 Rate of Climb/ Decent (fpm) Refuel (Y, N) 480 0 0 0 0 0 423 0 0 0 0 0 0 0 0 0 0 0 N N N N N N N N N N N N N N N N N N 64 UAV #2 Waypoints A B C D E F G H I J K L M N O P Q R S T U V UAV Position Distance Angle from from Search Search Center Center (miles) (degrees) Segment Type (S, P) for Straight, Polar Waypoint Corner Turn Radius (feet) 1.226 1.226 1.005 1.005 0.784 0.784 0.563 0.563 0.341 0.341 0.120 0.120 1.917 90 250 250 86 86 253 253 70 80 270 265 85 0 S P S P S P S P S P S P S 0 0 0 0 0 0 0 0 0 0 0 0 0 1.917 1.586 1.586 1.254 90 90 -1 -1 P S P S 0 0 0 0 1.254 0.912 0.912 0.295 0.295 91 91 -2 -2 90 P S P S P 0 0 0 0 0 Camera Ground Footprint Speed Width At (mph) Ground (feet) 0 1178 1178 1178 1178 1178 1178 1178 1178 1178 1178 1178 0 910 910 910 910 910 910 910 910 910 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 Rate of Climb/ Decent (fpm) Refuel (Y, N) 740 0 0 0 0 0 0 0 0 0 0 0 79 0 0 0 0 0 0 0 0 0 N N N N N N N N N N N N N N N N N N N N N N 65 UAV #3 Waypoints A B C D E F G H I J K L M N O P Q R S T U V UAV Position Distance Angle from from Search Search Center Center (miles) (degrees) 1.952 1.952 1.753 1.753 1.554 1.554 1.354 1.354 1.155 1.155 0.956 0.956 0.757 0.757 0.557 0.557 0.259 0.259 0.649 0.649 0.531 0.531 1 -111 -111 2 2 -112 -112 3 3 -113 -113 3 3 -113 -113 4 4 -115 90 0 0 90 Segment Type (S, P) for Straight, Polar Waypoint Corner Turn Radius (feet) S P S P S P S P S P S P S P S P S P S P S P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Camera Ground Footprint Speed Width At (mph) Ground (feet) 0 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 0 624 624 624 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 65 70 80 Rate of Climb/ Decent (fpm) Refuel (Y, N) 683 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -308 0 0 0 N N N N N N N N N N N N N N N N N N N N N N 66 UAV#4 Waypoints A B C D E F G H I J K L M N O P Q R S T U V W X UAV Position Distance Angle from from Search Search Center Center (miles) (degrees) 1.852 1.852 1.653 1.653 1.454 1.454 1.255 1.255 1.055 1.055 0.856 0.856 0.657 0.657 0.458 0.458 0.358 0.358 0.159 0.159 0.059 0.059 0.767 0.767 2 -112 -112 3 3 -113 -113 4 4 -114 -114 5 5 -115 -115 6 6 -116 -116 7 7 -130 90 0 Segment Type (S, P) for Straight, Polar Waypoint Corner Turn Radius (feet) S P S P S P S P S P S P S P S P S P S P S P S P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Camera Ground Footprint Speed Width At (mph) Ground (feet) 0 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 528 0 624 80 80 80 80 80 80 80 80 80 80 80 80 80 80 65 60 60 55 55 52 52 52 80 80 Rate of Climb/ Decent (fpm) Refuel (Y, N) 720 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -338 0 N N N N N N N N N N N N N N N N N N N N N N N N 3.5 Mission Time and Resource Requirements We calculated the time it would take for our UAS to finish searching each zone, and as the UAVs are searching concurrently, the maximum time is the total mission duration overall. The table with our calculations, and the total mission time highlighted, is shown below: 67 UAV# 1 2 3 4 Sensor Payloads X1000 + X3000 X1000 + X3000 X3000 X3000 Searched Area No-Tree, Short-Tree No-Tree, Short-Tree Tall-Tree, Short-Tree Tall-Tree, Short-Tree Time (minutes) 20.2163 20.4502 20.4927 20.1471 In conclusion, the search mission can be accomplished with 21 minutes including the time needed for turn-around identification. 68 4. Document the Business Case 4.1 Identify targeted commercial applications Innovative Solution’s target market will consist of the international, federal, and state government, armed forces and military endeavors, local law enforcement agencies, as well as private corporations and individuals. Innovative Solutions will market its specialized, efficient programs to all of these persons in varying capacities to suit their individualized UAS needs, with an emphasis on acquiring contracts with governmental agencies and other parties with considerable, significant demand. By offering our services to a variety of parties, we seek to maximize and diversify our potential clientele to ensure both maximum profit and stability as a company. Eager to capitalize on the relatively new field of UAS in search and discovery, we are prepared to penetrate the space and compete with established unmanned aircraft manufacturers for market share. Innovative Solutions will strive to provide the best services on the market at the lowest costs possible in order to keep customer satisfaction high and to ensure that the integrity, quality, and efficiency of our UAV designs are unwavering. We will be looking to incorporate new and innovative technologies into our design going forward, with the hope of minimizing cost while maximizing efficiency for our clients. We recognize that each potential customer, whether coming from the private or public sector, has their own distinct needs and specifications. We would look to offer our services to as many parties as possible by utilizing the technology that would allow us to do so. Early on in our conceptual design phase, we entertained the idea of utilizing the cloud to allow a variety of customers to access our systems. Unfortunately, the potential for lag and other technical issues was too great at this point in time for us to seriously consider this as a business strategy. We are, however, closely following research being conducted at the Johns Hopkins Applied Physics Lab in Maryland, where researchers are looking to drastically reduce these technical issues specifically in regards to communication between UAVs and ground information systems. This is just one example of a possible technological advance that we would look to take advantage of 69 eventually. Innovative Solutions would also look into possibly adding thermal sensors into our payload. This year, the Real World Design Challenge prompt revolved around the search and rescue of mission persons. According to the National Institute of Justice, approximately 2,300 American adults are reported missing on a daily basis; this indicates an average of around 839,500 missing American adults throughout the year. This is, clearly, a shocking and very disturbing number. However, what is perhaps even more disturbing is that approximately 800,000 children in the United States are reported missing annually (this figure being distinct from the aforementioned figure of adults who are reported missing every year). We feel that we can lend a helping hand to this pressing issue, and through Innovative Solutions, we seek to ensure that more of these lost individuals will be found and returned safely to their loving families than ever before. Unmanned vehicles equipped with the capabilities of our design constitute promising tools for conducting reconnaissance tasks in both military and humanitarian conditions, due to the removal of any direct risk to human life when compared to a 'manned' aircraft. The applications of such aircraft are vast, and stretch far beyond the domestic search and rescue missions of mission persons. There is even the possibility that in the future our drones will be able to be contracted to the government or American military as a way to search for missing servicemen and women. Also, in the future Innovative Solutions would likely have the opportunity to expand to overseas markets, allowing for much more revenue to be brought in as well as for many more peoples’ lives to be saved. 4.2 Amortized System Costs 4.2.1 Initial Costs Our total initial cost is $247,099.13 dollars. This figure was found in the following manner: 70 The personnel cost is not included in this figure since the personnel total is our operational cost, and thus not needed to construct the system itself. We can break down our initial cost into a table such as this: Initial Cost 2 x Design A UAVs = $101,193.20 2 x Design B UAVs = $84,793.20 Ground Station total = $61,111.53 Initial Total Cost = $247,097.93 4.2.2 Direct Operational Cost per Mission Operational Personnel Resource Resource Cost Per Hour Number of Total Cost Per-9 Positions Required Hour Payload Operator $150.00 2 $2,700.00 Range Safety/Aircraft Launch & Recovery/Maintenance Safety Pilot $175.00 1 $1,575.00 $100.00 4 $3,600.00 Operational Pilot $150.00 4 $5,400.00 Total Cost Per-Hour $13,275.00 The direct operational cost per mission is, in our case, our personnel selection cost. We arrived at the number of 9 hours due to the fact that we will be driving 3.5 hours each way, .5 hours for set-up and tear-down, plus our search time of 20.5 minutes. Thus, this rounds up to 9 hours we will have to pay our personnel per mission. Also, the cost perhour would be $1,475.00. We are using the E-20 electric engine so we incur not fuel but rather battery costs, which have already been accounted for under the airframe component of our system initial cost. 71 4.2.3 Amortization To ensure that we recoup our funds and are able to meet our business goals, we must ensure that we charge enough per mission that we are able to gradually able to pay off our initial system cost. To find this amortized cost, we can use the following formula: Here, we add the initial system cost to the operational cost per-hour over 50 missions, and then divide this sum by 50. The resultant number is our amortized cost per mission. In our case: 247097.93 + (1475 * 9)*(50) ______________________ = 18,216.96 50 The result of this calculation means that we would have to charge clients at least $18,216.96 per mission to pay off our initial system cost over 50 missions even though cost incurred to us per mission (“operational cost”) is only $13,275 assuming the average time for recovery missions may be 9 hours including time to drive to and from the launch site. If we charge $18,216.96, it will only take fifty missions for Innovative Solutions to cover its initial systems costs along with all personnel costs. It is very likely that Innovative Solutions will be able to complete these fifty missions within a year, as 2,300 people go missing in the United States every day, and in Colorado alone 108 search and rescue missions were performed in 2012, often at costs over $20,000. It will only cost $663,750.00 to execute 50 missions which last 20.5 minutes not including driving time, which is a very reasonable amount. 72 4.3 Market Assessment After profuse research about the search and rescue market, we arrived at a variety of conclusions. The first such conclusion is that search and rescue missions can be very costly. The average cost for a mission lasting only a couple hours is upwards of $17,000.00. However, some searches which last for more than twelve hours can cost up to $337,000.00. This is a very large amount. The cost to use equipment such as planes and boats alone is quite a large sum of money. It costs $6,625.00 per hour for the Coast Guard to use a rescue helicopter in a search and rescue mission, and it costs $7,600.00 per hour for the use of a C-130 turboprop search airplane. However, the cost for these vehicles for a search and rescue mission will be higher than represented by these numbers. While it may take less time for the C-130 or the helicopter to arrive at the search destination, they also have to do safety checks and fuel up the vehicles. This takes a long time, and while they are doing this, we will be able to be driving to our destination already. Also, our per-hour cost for our UAV includes travel time for up to three hours each way plus three hours of search time. Besides just looking at the overall cost of search and rescue missions, we also decided to research the costs of individual vehicles used in search and recovery missions. The MC-12W intelligence, surveillance and reconnaissance plane costs $17,000,000.00 for one unit. The Scan Eagle UAV system costs $3,200,000.00 per unit. And finally, the HazMat Bot search and recovery robot costs $150,000.00. After comparing the cost of our UAVs to the costs of these units, it is obvious that our system is far less expensive all while exceeding expectations of efficiency. While it may take a combination of any of the abovementioned vehicles, volunteers, search dogs, etc. many hours to find a missing person, it will only take our system 20.5 minutes. When someone is stranded in the wild they often don’t have hours, and every minute counts towards their survival. Also, these searches often cost above $16,000.00. So not only is our service faster, it is also more cost effective per-hour, making it the clear choice for any customer seeking rapid, effective, and relatively inexpensive help. 73 Also worth noting is that our location greatly aids us in attracting potential business. As we are based in Colorado Springs, Colorado, there are twenty-five major state and national parks within 3 ½ hours of our location, including Rocky Mountain National Park, Cheyenne Mountain State Park, and the Golden Gate Canyon State Park. The cost for these missions, as well as the mission time including driving, will be the same as for the fifty missions originally performed at Philmont Ranch, New Mexico. Thousands of people go missing in national and state parks every year, and as such, we will be able to save more people as well as to gain reinvestment capital from the large amount of missions we would be able to perform from a location such as this. The Innovative Solutions UAV systems are much more advanced and suited to the job of search and recovery than that of competitors. The first UAV system uses one piece of X1000 sensor payload and one piece of X3000 sensor payload. The second UAV system uses one piece of X3000 sensor payload. This combination of UAV systems greatly improves the efficiency of our drones in locating an objective. The X1000 sensor is for the detection of an objective, and the X3000 is for the identification of that object. Even going at a high speed of 80 mph, a drone can still identify an object in only five seconds. In addition to this, the drone has a flight time of 9 hours. This lengthy span of time coupled with the technology utilized in sensory payload equipment makes the Innovative Solutions drone much more advanced and suited for the job than those of the competitors. Another advantage of the Innovative Solutions UAV system is that it is also much more environmentally friendly than any of the other vehicular options available for search and recovery. Rather than using gasoline, our UAVs are powered by an electric engine. This is a very quiet engine, and as such it will not bother people if it must fly over areas which are populated. Also, since the UAV is powered by electric it has a very small carbon footprint. So, not only is our UAV environmentally friendly in this regard, but it is also a much more environmentally friendly option if we must search in a national park or otherwise where a diesel engine would pollute the air. Finally, as our UAV is powered 74 by just electricity, its per-mission cost is quite low, allowing us to engage in many missions for a much lower cost than any other vehicle. 4.4 Cost / Benefits Analysis and Justification Previously, we had utilized one UAV design which used three X1000 sensor payloads for detection and one X3000 sensor payloads for identification. Because each sensor is so expensive, we examined the sensor payload specs to see if there might be a way that the X3000 could fulfill both roles, as the X1000 certainly is not adequate for both. The X3000 sensor payload features continuous zoom between 5 and 55 degrees, and we realized that we would have to zoom out to approximately 40 degrees to identify the object in the two zones with limited line of sight. We decided to employ the use of four UAVs in order to complete our search operations for a variety of reasons. The first reason is that this number is relatively low which would allow the launch of these drones to be quite rapid. Our response time could be quite rapid, as we can reach many places where people go missing within a three hour drive from our location in Colorado Springs, Colorado. The second reason is that we have determined that in searching a high-tree area with two of the drones and searching the low/no-tree area with two the total search time would take only twenty and one-half minutes. Another reason we chose this number is that this relatively small number of UAVs does not take a large amount of people to control them. This being the case Innovative Solutions is able to save money on additional personnel costs and use this money to improve the services offered to the customer. Also, if we had to search an open area then we could potentially use less than four UAVs which would decrease the cost even more. Finally, we decided to go with four UAVs rather than a slightly larger number such as eight because we determined that while the search time would go down, the cost would go up so much that it would counter any benefit gained from the lower search time. 75 This graph is to show why we decided to use four UAVs rather than 30. While this amount would decrease the search time, it would also greatly increase the cost, thus making four our best option for minimizing our objective function. 76 Works Cited "AeroVironment Wins $2.5M U.S Airforce Contract to Supply Digital Wasp AE Small Unmanned Aircraft System." Unmanned Systems Technology. Unmanned Systems News, 23 May 2012. Web. 18 Jan. 2013. 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