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• Taken from MSD1

Customer Need # Importance Description

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 appearanceCN3 9 Human controlled planeCN4 3 No special flight skill requiredCN5 9 Use existing base station designCN6 9 Tether tension is measured and recorded during flightsCN7 9 Tether direction is measured and recorded during flights

CN8 9 Videos with accompanying data files of all flight tests (even ones that don’t work)

CN9 9 Able to survive crashes with minor repairs (short downtime)

CN10 9 Replaceable PartsCN11 3 Maintenance GuideCN12 9 Design a robust glider which meets the above repair

requirements and can be piloted in the cyclical path.

Engineering Requirements• Taken from MSD1

Rqmt. # Importance Type Source Engr. Requirement (metric) Unit of Measure Marginal Value Ideal Value Comments/Status Test (Verification)

S1 9 Aero CN1 Drag Coefficient -- 0.2 0.05 Calculation & XLFR5

S2 9 Aero CN1 Lift Coefficient -- 0.7 1 Calculation & XLFR5

S3 3 Aero CN1 Wingspan ft 3.3 3 Customer Constraint Tape Measure

S4 3 Aero CN4 Cooper-Harper Rating -- 3 1 Subjective

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 Capability Exists (P14462) LabVIEW

S15 9 Mechanical CN1 Mechanical Weight lbs 4 3 Scale

S16 9 Mechanical CN1 Service Ceiling ft 75 100 FAA Regulation LabVIEW

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 Training Documetation Stopwatch

Areas of Design• Design Intent mapped to Physical Parameters• Partially from MSD1

Area of Design

Fuselage Design

Wing Design

Horizontal Tail Design

Fuselage Material

Wing/Tail Material

On-Board Electronics

Plane Take-Off Method

Plane-to-Tether Connection

Prop Location

Non-Destructively Achieve Tether Tension

Flight Path

Non-Destructive Landing

Proposed System Design• Taken from MSD1Areas of Design 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 – DevinCustomer Rqmt. #

Importance Description Did We Meet? Why Not?

CN1 9Tethered glider system (with electric prop assist for launching) that demonstrates at least 3 minutes of continuous circular flight path with taunt tether.

NoWe were unable to get into the flight path.

CN2 1 Clean appearance Marginal Due to electronics issue, electronics bay is cramped and compact.

CN3 9 Human controlled plane Yes NACN4 3 No special flight skill required Yes NACN5 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 9Videos with accompanying data files of all flight tests (even ones that don’t work)

YesNA

CN9 9 Able to survive crashes with minor repairs (short downtime) Yes NACN10 9 Replaceable Parts Yes NACN11 3 Maintenance Guide Yes NACN12 9 Full Systems Drawing Package Yes NA

CN13 3 All parts ordered by the end of MSD1 MarginalSnuggie parts and pieces like glue were delayed.

CN14 1 Team trained for use of foam cutter Yes NA

Risk Assessment – Hindsight Risk Did We Experience it? Explain. Were We Prepared?

Poor Weather No. Our plane was delayed and prevented bad weather from inhibiting our performance. For more details please see Carl's wetather report.

Our action to minimize risk was sufficient for the problem at hand.

Structural repairs put project over budget

No. We had sufficient supplimental material for all our necessary repairs. Yes our action to minimize risk was sufficient.

Inability to maintain required flight path Yes. Due to motor and servo twitch we struggled significantly to control to plane and take off. Our action to minimize risk was not sufficient.

Base Station Break No. We did not get to collecting data from the base station. NA

Electronics failure/malfunctionYes. Our speed controller took damage upon impact. Our action to minimize risk was not sufficient.

Poor material choice discovered late in design

Yes, our wing and tail spars were not sufficient for impacts and loading.

While our action to minimize risk was not sufficient we were able to repair with lab components and extra parts.

Inability to properly identify/understand causes of flight failure

Yes. We believe we have a sufficient cause of problems but we cannot adequately test.

Our action to minimze risk was not sufficient.

Lengthy repairs No. Our repair downtime did not extend longer than one day after initial impact fractures. Our action to minimize risk is sufficient.

Insufficient thrust for Take-Off Yes. Our speed controller has caused inconsistency in producing thrust. Our action to minimize risk was not sufficient.

Failure to Land SoftlyYes. Our glider has needed repairs due to hard crashes. Our action to minimize risk was not sufficient.

Wings Dislocate Mid-Flight No. Our wing support was sufficient to prevent dislocation mid flight. Our action to minimize risk was not needed.

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. Our action to minimize risk was sufficient.

Plane does not fly Yes. We think aerodynamic analysis may have been incomplete.

Our action to minimize risk was not sufficient. It would have been better if all of us had taken flight dynamics before MSD.

Lose connection with RC TransmitterNo we did not lose connection with transmitter. Our actions to minimize risk was sufficient.

Joint fatigue failure on spars We did experience failures but the cause was not through fatigue.

Our actions to minimize risk was not sufficient.

Structure sees significant failure on impactYes we experienced failure on impact.

Our action to minimize risk was not sufficient.

Weight shifts inside of plane during flightNo we did not experience this risk.

Our action to minimize risk was not necessary.

Inability to manufacture selected airfoilNo we did not experience this risk. Our action to minimize risk was sufficient.

Servo hardware loss in flightNo we did not experience this risk.

Our action to minimize this risk was sufficient.

Failure of 3D Printed Fuselage Glued Assembly No we did not experience this risk.

Our action to minimize risk was not necessary.

Pilot FatigueNo we did not experience this risk. Our action to minimize risk was sufficient.

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