P15462 – TETHERED WIND
ENERGY PLANE
Project Background
• The goal of this project is to design, build, and reliably test
an unpowered, human-controlled tethered glider
specifically for use as an Airborne Wind Turbine system
(AWT).
Customer Requirements
Customer Need # Importance
Description
9
Tethered glider system (with electric prop assist for launching)
• CN1
Taken from MSD1
CN2
CN3
CN4
CN5
CN6
CN7
1
9
3
9
9
9
CN8
9
CN9
9
CN10
CN11
CN12
9
3
9
that demonstrates at least 3 minutes of continuous circular
flight path with taunt tether.
Clean appearance
Human controlled plane
No special flight skill required
Use existing base station design
Tether tension is measured and recorded during flights
Tether direction is measured and recorded during flights
Videos with accompanying data files of all flight tests (even
ones that don’t work)
Able to survive crashes with minor repairs (short downtime)
Replaceable Parts
Maintenance Guide
Design a robust glider which meets the above repair
requirements and can be piloted in the cyclical path.
Engineering Requirements
Rqmt. # Importance
S1
Type
Source
Engr. Requirement (metric)
• 9Taken
from
MSD1
Aero
CN1
Drag Coefficient
Unit of Measure Marginal Value
Ideal Value
Comments/Status
Test (Verification)
--
0.2
0.05
Calculation & XLFR5
Calculation & XLFR5
S2
9
Aero
CN1
Lift Coefficient
--
0.7
1
S3
3
Aero
CN1
Wingspan
ft
3.3
3
S4
3
Aero
CN4
Cooper-Harper Rating
--
3
1
S5
3
Aero
CN3
Flight Stability
Binary
Marginal
Complete
Static Stability Criteria
Calulation & Flight Testing
S6
3
Aero
CN11
Profile of Surface for Airfoil Manufacturing
in
0.1
0.05
GD&T
ASTM Standard
S7
9
Aero
CN1
Efficiency of Wing
-
0.82
0.9
Calculation
S8
1
Aero
CN1
Fixed Angle of Attack
deg
0
3
Protractor
S9
9
Electrical
CN7
Horizontal Potentiometer Recording
Binary
Marginal
Complete
Capability Exists (P14462)
LabVIEW
S10
9
Electrical
CN7
Vertical Potentiometer Recording
Binary
Marginal
Complete
Capability Exists (P14462)
LabVIEW
S11
9
Electrical
CN1
Electronics Weight
lbs
0.484
0.4
Motor not included
Scale
S12
9
Financial
CN1
Initial Cost
$
250
200
BOM
S13
3
Financial
CN10
Repair Cost
$
100
50
BOM
S14
9
Mechanical
CN6
Tether Tension
lbs
5
23
S15
9
Mechanical
CN1
Mechanical Weight
lbs
4
3
S16
9
Mechanical
CN1
Service Ceiling
ft
75
100
S17
3
Mechanical
CN1
Flight Path Diameter
ft
25
50
LabVIEW
S18
9
Mechanical
CN1
Maximum Glider Speed
mph
30
45
LabVIEW
S19
3
Mechanical
CN1
Fuselage Cross Sectional Area
in2
20
16
Caliper
S20
9
Mechanical
CN9
Fuselage Material Tensile Strength
psi
CF is ideal material
MatWeb Lookup
S21
9
Mechanical
CN9
Wing Material Tensile Strength
psi
Foam Mat'l Comparison
MatWeb Lookup
S22
3
Time
CN9
Repair Downtime
hour
24
1
Stopwatch
S23
3
Time
CN8
Time Between Flights
min
30
5
Stopwatch
S24
3
Time
CN4
Training Flight Hours
hour
12
1
Customer Constraint
Tape Measure
Subjective
Capability Exists (P14462)
LabVIEW
Scale
FAA Regulation
Training Documetation
LabVIEW
Stopwatch
Areas of Design
• Design Intent mapped to Physical Parameters
• Partially from MSD1
Area of Fuselage
Design Design
Wing
Design
NonDestruc
Horizontal
Plane Plane-toNonFuselage Wing/Tail On-Board
Prop
tively Flight
Tail
Take-Off Tether
Destructive
Material Material Electronics
Location Achieve Path
Design
Method Connection
Landing
Tether
Tension
Proposed System Design
Areas
of Design
• Taken
from
MSD1
Final System
Fuselage Design
Aerodynamically Optimized Rectangular Volume
Wing Design
Linear Taper, Fixed Angle of Attack, Dihedral, Flaps
Horizontal Tail Design
H-Shaped Tail
Fuselage Material
Foam with 3-D Printed Protective Electronic Housing
Wing/Tail Material
Carbon Fiber Strip Leading Edge, Foam with Coating
On-Board Electronics (Control Feedback)
In-Flight Data Recorder with Software
Plane Take-Off Method
Propeller hand launch
Plane-to-Tether Connection
One Point/Ball and Socket Joint
Prop Location
Push Prop on back of fuselage
Non-Destructively Achieve Tether Tension
Hand Spool
Flight Path
Offset Vertical Circle
Non-Destructive Landing
Land on Airframe "Smooth"
MFG - Foam Parts
• Foam Cutter
• Learning Curve
• Limitations
• Wing and Tail Airfoils
• Image(s) Here
MFG - Foam Parts
• Manual Foam Cutter
• Spar Holes
• Fuselage
• Image(s) Here
MFG - 3D Printed Fuselage
• How Design changed
to reduce cost
• Key Parameters for
ordering
• Post-Processing
• Image(s) Here
MDG - 3D Printed Motor Mount
MFG - Spar Connections
• Wing Spar/Tail
Spar/Boom
• Anti-rotation spars
• CF wrap after break
• Tail spar reinforcement
MFG - Electronics Bay
• Electronics Bay Cut
Out
• Cut-outs for batteries
Assembly - Tail
Assembly - Wing
Assembly - Fuselage
Weather DATA - Carl
MSD II – Pre-Flight Opportunities
• Foam Cutter - MK
• Motor Mount/ propeller - MK
• Control Surfaces – MK/CS
• CG location/ counterweights – MK
• Budget Constraints/ Problems - MZ
Final System Design - MK
Flight Testing - Maginn
• Hand Launches
• Car Testing
• Longboard (proxy
winch system)
• Tether to board
• Tether to plane
MSD II – Post-Flight Opportunities
• Nose shearing off - MZ
• Wing Spar and Tail Spar Failure - MZ
• ESC Failure/ Motor Intermittency - MK
• Tail Drag – Wheel –MZ
• Budget Constraints/ Problems - MZ
Engineering Requirements - Maginn
Customer Requirements – Devin
Customer
Rqmt. #
Importance
CN1
9
Tethered glider system (with electric prop assist for launching) that
demonstrates at least 3 minutes of continuous circular flight path with taunt
tether.
CN2
1
Clean appearance
CN3
9
Human controlled plane
Yes
NA
CN4
3
No special flight skill required
Yes
NA
CN5
9
Use existing base station design
Yes
NA
CN6
9
Tether tension is measured and recorded during flights
No
We were unable to get into
the flight path.
CN7
9
Tether direction is measured and recorded during flights
No
We were unable to get into
the flight path.
CN8
9
Videos with accompanying data files of all flight tests (even ones that don’t
work)
Yes
Description
Did We Meet?
No
Marginal
Why Not?
We were unable to get into
the flight path.
Due to electronics issue,
electronics bay is cramped
and compact.
NA
CN9
9
Able to survive crashes with minor repairs (short downtime)
Yes
NA
CN10
9
Replaceable Parts
Yes
NA
CN11
3
Maintenance Guide
Yes
NA
CN12
9
Full Systems Drawing Package
Yes
NA
CN13
3
All parts ordered by the end of MSD1
CN14
1
Team trained for use of foam cutter
Marginal
Yes
Snuggie parts and pieces like
glue were delayed.
NA
Risk Assessment – Hindsight
Risk
Did We Experience it? Explain.
Poor Weather
No. Our plane was delayed and prevented bad weather
from inhibiting our performance. For more details please Our action to minimize risk was sufficient for the
see Carl's wetather report.
problem at hand.
No. We had sufficient supplimental material for all our
necessary repairs.
Yes our action to minimize risk was sufficient.
Structural repairs put project over
budget
Were We Prepared?
Inability to maintain required flight path Yes. Due to motor and servo twitch we struggled
Base Station Break
Electronics failure/malfunction
significantly to control to plane and take off.
No. We did not get to collecting data from the base
station.
Our action to minimize risk was not sufficient.
Yes. Our speed controller took damage upon impact.
Our action to minimize risk was not sufficient.
Poor material choice discovered late in Yes, our wing and tail spars were not sufficient for
design
impacts and loading.
Inability to properly identify/understand Yes. We believe we have a sufficient cause of problems
causes of flight failure
but we cannot adequately test.
Lengthy repairs
Insufficient thrust for Take-Off
Failure to Land Softly
Wings Dislocate Mid-Flight
NA
While our action to minimize risk was not
sufficient we were able to repair with lab
components and extra parts.
Our action to minimze risk was not sufficient.
No. Our repair downtime did not extend longer than one
day after initial impact fractures.
Our action to minimize risk is sufficient.
Yes. Our speed controller has caused inconsistency in
producing thrust.
Our action to minimize risk was not sufficient.
Yes. Our glider has needed repairs due to hard crashes.
No. Our wing support was sufficient to prevent
Our action to minimize risk was not sufficient.
Risk Assessment (cont.)
Risk
Did We Experience it? Explain.
Were We Prepared?
Servomotor lever arm breaks
No. Our servo arms were not overstressed.
Our action to minimze risk was not needed.
Practice flight is delayed further
No. Plane assembled easily and was not destroyed on first
flight.
Our action to minimize risk was sufficient.
Do not provide enough power
No. Our batteries can provide sufficient thrust for
approximately 4 to 5 minutes.
Plane does not fly
Lose connection with RC Transmitter
Joint fatigue failure on spars
Structure sees significant failure on impact
Weight shifts inside of plane during flight
Inability to manufacture selected airfoil
Servo hardware loss in flight
Failure of 3D Printed Fuselage Glued
Assembly
Pilot Fatigue
Yes. We think aerodynamic analysis may have been
incomplete.
Our action to minimize risk was sufficient.
Our action to minimize risk was not
sufficient. It would have been better if all
of us had taken flight dynamics before
MSD.
No we did not lose connection with transmitter.
Our actions to minimize risk was sufficient.
We did experience failures but the cause was not through
fatigue.
Our actions to minimize risk was not
sufficient.
Our action to minimize risk was not
sufficient.
Our action to minimize risk was not
necessary.
Yes we experienced failure on impact.
No we did not experience this risk.
No we did not experience this risk.
No we did not experience this risk.
Our action to minimize risk was sufficient.
Our action to minimize this risk was
sufficient.
Our action to minimize risk was not
necessary.
No we did not experience this risk.
Our action to minimize risk was sufficient.
No we did not experience this risk.
Accomplishments- MZ
Lessons Learned - MZ
• Plane Design is vHARD
• Planes are expensive
• Hand prop launch may not be best launch method
• Hollow CF tubes are not as durable as expected
• H-Tail is not a survivable/durable design
• Design of model aircraft vs. full scale
Moving Forward - MZ
• Purchase new speed controller
• 3D print control surfaces (lightweight/rigid)
• Remove material from motor mount plates to allow for
more airflow
• Winch/launch system design
• 2nd wheel for tail stability
• Snuggy design changes