P15462 – TETHERED WIND ENERGY PLANE Devin Bunce Matthew Kennedy Matthew Maginn Carl Stahoviak Matthew Zebert

Agenda MSD 1 Project Background Review of Customer & Engineering Requirements Proposed System Design MSD 2 Manufacturing Assembly Pre-Flight Opportunities Flight Testing Post-Flight Opportunities Final System Accomplishments related to Customer & Engineering Requirements Risk Review Lessons Learned Moving Forward

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 #ImportanceDescription CN19Tethered glider system (with electric prop assist for launching) that demonstrates at least 3 minutes of continuous circular flight path with taunt tether. CN21Clean appearance CN39Human controlled plane CN43No special flight skill required CN59Use existing base station design CN69Tether tension is measured and recorded during flights CN79Tether direction is measured and recorded during flights CN89Videos with accompanying data files of all flight tests (even ones that don’t work) CN99Able to survive crashes with minor repairs (short downtime) CN109Replaceable Parts CN113Maintenance Guide CN129Design a robust glider which meets the above repair requirements and can be piloted in the cyclical path.

Engineering Requirements Taken from MSD1 Rqmt. #ImportanceTypeSource Engr. Requirement (metric)Unit of MeasureMarginal ValueIdeal ValueComments/StatusTest (Verification) S19AeroCN1Drag Coefficient Calculation & XLFR5 S29AeroCN1Lift Coefficient Calculation & XLFR5 S33AeroCN1Wingspanft3.33Customer ConstraintTape Measure S43AeroCN4Cooper-Harper Rating--31 Subjective S53AeroCN3Flight StabilityBinaryMarginalCompleteStatic Stability Criteria Calulation & Flight Testing S63AeroCN11Profile of Surface for Airfoil Manufacturingin GD&TASTM Standard S79AeroCN1Efficiency of Wing Calculation S81AeroCN1Fixed Angle of Attackdeg03 Protractor S99ElectricalCN7Horizontal Potentiometer RecordingBinaryMarginalCompleteCapability Exists (P14462)LabVIEW S109ElectricalCN7Vertical Potentiometer RecordingBinaryMarginalCompleteCapability Exists (P14462)LabVIEW S119ElectricalCN1Electronics Weightlbs Motor not includedScale S129FinancialCN1Initial Cost$ BOM S133FinancialCN10Repair Cost$10050 BOM S149MechanicalCN6Tether Tensionlbs523Capability Exists (P14462)LabVIEW S159MechanicalCN1Mechanical Weightlbs43 Scale S169MechanicalCN1Service Ceilingft75100FAA RegulationLabVIEW S173MechanicalCN1Flight Path Diameterft2550 LabVIEW S189MechanicalCN1Maximum Glider Speedmph3045 LabVIEW S193MechanicalCN1Fuselage Cross Sectional Areain Caliper S209MechanicalCN9Fuselage Material Tensile Strengthpsi CF is ideal materialMatWeb Lookup S219MechanicalCN9Wing Material Tensile Strengthpsi Foam Mat'l ComparisonMatWeb Lookup S223TimeCN9Repair Downtimehour241 Stopwatch S233TimeCN8Time Between Flightsmin305 Stopwatch S243TimeCN4Training Flight Hourshour121Training DocumetationStopwatch

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- Destruc tively Achieve Tether Tension Flight Path Non- Destructive Landing

Proposed System Design Taken from MSD1 Areas of DesignFinal System Fuselage DesignAerodynamically Optimized Rectangular Volume Wing DesignLinear Taper, Fixed Angle of Attack, Dihedral, Flaps Horizontal Tail DesignH-Shaped Tail Fuselage MaterialFoam with 3-D Printed Protective Electronic Housing Wing/Tail MaterialCarbon Fiber Strip Leading Edge, Foam with Coating On-Board Electronics (Control Feedback)In-Flight Data Recorder with Software Plane Take-Off MethodPropeller hand launch Plane-to-Tether ConnectionOne Point/Ball and Socket Joint Prop LocationPush Prop on back of fuselage Non-Destructively Achieve Tether TensionHand Spool Flight PathOffset Vertical Circle Non-Destructive LandingLand on Airframe "Smooth"

MFG - Foam Parts Foam Cutter Foam cutting manual lacked information Steep learning curve Tapered Wing Produced in 3 sections Difficulties with taper, TE thickness, hole Horizontal & Vertical Tails

MFG - Foam Parts Manual Foam Cutter Spar Holes Difficulty producing acceptable hole tolerances with foam cutter Manual Foam cutter worked much better Fuselage Fuselage cut manually for same reasons Image of manual foam cutter

MFG - 3D Printed Fuselage Design modifications made to reduce material & cost Wall thickness reduced Production in multiple parts considered Post-Processing Spar holes rounded Wiring thru holes enlarged Motor mount hole enlarged for snug fit

MFG - Spar Connections Wing Spar/Tail Spar/Boom Hollow CF tubes Anti-rotation spars in wing and horizontal tail CF wrap after break Tail spar reinforcement

MFG - Electronics Bay Electronics Bay Cut Out Cut with manual foam cutter Houses: All 3 batteries Speed Controller Reciever Wring for servos and motor Large battery placed in nose to shift CG forward

Assembly - Tail

Assembly - Wing

Assembly - Fuselage

Weather Data

MSD II – Pre-Flight Opportunities Foam Cutter Motor Mount/ propeller Control Surfaces CG location Budget Constraints

Foam Cutting Inverse Taper Thin Trailing Edge Spar Hole

Motor Mount and Propeller Prop cannot mount to motor Motor unthreads propeller No method to mount motor to fuselage

Control Surfaces Trailing Edge of EPP too thin Attempted fiber glassing EPO Foam Fiber glassing did not meet needs, used cardboard

Center of Gravity Location CG Location not aligned with design post assembly Added counterweights to the front of the nose for adjustment

Flight Testing - Maginn Over 55 Flights in MSD II Hand Launches First flight impact Initial problems discovered Car Tethered Testing Determining stability and control surface performance Longboard (proxy winch system) Tether to board Difficult to maintain velocity Tether to plane Difficult to maintain tension

Flight Testing Specification Number Importance Source (PRP, interview, etc) Specification (Metric)Unit of MeasureTarget ValueToleranceComments/StatusLink to planConcluded Condition S43Eng ReqMax Roll Angledegrees8010Controllable at 75 degLink to S4 planO S69Eng ReqInput EffectivenessCooper-Harper Rating319 or 10 on CH RatingLink to S6 planX S73Eng ReqStatic StabilityStable vs UnstableYesNeutralNeutral StabilityLink to S7 planO S181Cust ReqService Ceilingft10025 Link to S18 planX S191Eng ReqFlight Path Diameterft5010 Link to S19 planΔ S203Eng ReqFlight Path Velocitymph4515 Link to S20 planΔ S259Cust ReqTime to Relaunchmin minLink to S25 planO SS19PerformanceLaunch Method-Yes-Skateboard WinchLink to SS1 planΔ KEY for Concluded condition XDoes not meet expectation ΔCaution-Undetermined if specification is met OMeets specification

MSD II – Post-Flight Opportunities Nose shearing off Wing Spar and Tail Spar Failure ESC Failure/ Motor Intermittency Tail Drag – Wheel Budget Constraints/ Problems

Electronic Speed Controller (ESC) Battery Eliminator Circuit broken after 1 st flight Added secondary power supply for receiver with 5V voltage regulator circuit Broken Chip Regulator Circuit

Final System Design Major Differences: Secondary battery supply Shorter fuselage with counterweights Addition of 3D printed motor mount Cardboard Control surfaces EPO Vertical Tails Spars carbon fiber wrapped together

Engineering Requirements - Maginn

Customer Requirements Customer Rqmt. # ImportanceDescriptionDid We Meet?Why Not? CN19 Tethered glider system (with electric prop assist for launching) that demonstrates at least 3 minutes of continuous circular flight path with taunt tether. No We were unable to get into the flight path. CN21Clean appearanceMarginal Due to electronics issue, electronics bay is cramped and compact. CN39Human controlled planeYes NA CN43No special flight skill requiredYes NA CN59Use existing base station designYes NA CN69Tether tension is measured and recorded during flightsNo We were unable to get into the flight path. CN79Tether direction is measured and recorded during flightsNo We were unable to get into the flight path. CN89 Videos with accompanying data files of all flight tests (even ones that don’t work) Yes NA CN99Able to survive crashes with minor repairs (short downtime)Yes NA CN109Replaceable PartsYes NA CN113Maintenance GuideYes NA CN129Full Systems Drawing PackageYes NA CN133All parts ordered by the end of MSD1Marginal Snuggie parts and pieces like glue were delayed. CN141Team trained for use of foam cutterYes NA

Risk Assessment – Hindsight RiskDid 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/malfunction Yes. 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 Softly Yes. 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.) RiskDid 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 Transmitter No 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 impact Yes we experienced failure on impact. Our action to minimize risk was not sufficient. Weight shifts inside of plane during flight No we did not experience this risk. Our action to minimize risk was not necessary. Inability to manufacture selected airfoil No we did not experience this risk.Our action to minimize risk was sufficient. Servo hardware loss in flight No 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 Fatigue No we did not experience this risk.Our action to minimize risk was sufficient.

Accomplishments Designed, built, and tested a plane with the full intension of it crashing into the ground Manufacturing Aerodynamic Surfaces with Foam Cutter Integral 3d printed fuselage Implemented the novel plane wrap or “snuggie” idea Repair time was very low Repair costs were low Successful lift off Team and individual growth

Lessons Learned Designing a plane is easier said than done Durable materials are much more expensive than normal model aircraft material Hand launching the plane is not the best method Hollow carbon fiber tubes have low radial strength H-Tail is not a durable design

Moving Forward Purchase new speed controller and receiver 3D print control surfaces (lightweight/rigid) Remove material from motor mount plates to allow for more airflow Winch/launch system design 2 nd wheel for tail stability Snuggie design changes