Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Aero 2010

1,349 views

Published on

Lecture to Lehigh University engineering students on the design of an electric powered model airplane seeking to break the World Endurance record.

Published in: Design, Business, Technology
  • Be the first to comment

  • Be the first to like this

Aero 2010

  1. 1. Aero Project 2010 Design a FAI World Record Setting Electric Powered Radio Controlled Model Airplane •Project design requirements, objectives and criteria •FAI Requirements and criteria •Physics of challenge •Design approaches ~ airplane •Design approaches ~ propulsion •Design trade studies •Program ScheduleCurrent Record; 12 h 36 min 46 secDate of flight: 30/07/2008
  2. 2. Project design requirements, objectives and criteria• Set World Endurance Record – Recognized by FAI – Just/vastly exceeding current record• Other Objectives and Criteria – Use commercial parts; • Motors • Batteries • Propellers • Flight controls etc. – Transportable in? – Weather conditions – Location of attempt – Level of autonomy / telemetry – Ease of construction / skill / tools / materials – Durability; • Number of flights anticipated • Number of attempts (set up and tear down) – Cost – Schedule – ?
  3. 3. Physics of Problem Speed LiftThrust Drag Weight
  4. 4. Physics of Flight Induced Drag Di Lift L • Other Vorticity Profile Drag = ½ ρ . V2 Sw. CDOLift, L = ½ ρ. V2 S. CL. e Drag D = Profile Drag + Induced DragIdeal Power Required L/D HP = T x V / 550 Flight Speed V plus induced speed vi Flight Speed V plus induced speed 2vi Flight Fuel Speed V Horse Weight Thrust Power of fuel . Mass Flow Rate m Propeller Weight of Disk area A engine and Efficiency ηp propeller Weight = Structure, controls + L/G Propulsion . Thrust T = m . 2 vi Fixed Useful Load Fuel Power Required = T . (V+ vi) Payload 550 . ηp
  5. 5. Flight Conditions for Maximum Endurance and Maximum Range at Fixed Weight ED UIR R EQ ER MINIMUM POW POWER, MAXIMUM Power ENDURANCERequired Drag 0 0
  6. 6. Gliding Flight Lift Speed RateOf Descent Drag is D/L Glide Slope Weight
  7. 7. Aerodynamic Trades
  8. 8. Reynolds Number Issues with Aspect Ratio
  9. 9. The Endurance Potential for Electric AirplaneLift, L = ½ ρ. V2 S. CL. e = WV= √ {W /(½ ρ. S. CL. e)} = K. √ {W/S}For a given airplane size and aerodynamics;V = K1 . √W For fixed airplane aerodynamicsV = K1 . √{We + Wb} the L/D at Vbe is aproximately constant with variation in gross weight*Power = V . Drag/550 = V . (W/L/D)/550Drag = W/(L/D) = K. W = K2 . {We + Wb}So Power = K3 . {We + Wb}1.5Endurance = K4. {Wb . Kb}/Power Endurance Potential with Battery Fraction 1.000Endurance = K5. Wb / {We + Wb}1.5 0.800 EnduranceMax endurance occurs with Wb = 2 x We 0.600 0.400But What should the size 0.200and weight be? 0.000 0 0.5 1 1.5 2 2.5 Battery Weight/Weight Empty
  10. 10. Model Design Parameters FAI REQUIREMENTS•Wing Area•Wing Aspect Ratio •Max weight 5Kg•Wing airfoil (flaps?) •Max wing + tail surface•Tail volume area 1.5 sq M•Control surfaces•Empty Weight (All Up Weight less Batteries)•Motor/gearbox/propeller•Maximum speed•Maneuver envelope•Drag enhancement / rate of descent•Maneuver capability•Maximum rate of climb•Minimum rate of climb•Visible altitude•Transport dimensions•Wing construction•Tail construction•Fuselage construction
  11. 11. Size and Weight FactorsAerodynamics (Reynolds Number) Size Weight (speed)Wing Loading (power required)Structural weight ~ SizeWing aspect ratio ~ aerodynamics ~ Structural weightWeather ~ wind capability ? aspect ratio (structure)Transportability ?Visibility in thermals ~ size aspect ratioPossible answer;Max size max weight A/R 10;Wing span 145 in mean chord 14.5 in, w/s 12 oz/sq ft.Empty weight 58 oz Battery weight 117 ozL/D max ~ 17
  12. 12. Approximate Performance for Guessed Design Solution Power Required at 70% overall propulsive efficiency Possible answer; •Max size max weight A/R 10; 160 •Wing span 145 in 140 •Mean chord 14.5 in, 120 •w/s 12 oz/sq ft. Power ~ watts •Empty weight 58 oz 100 •Battery weight 117 oz 80 •L/D max ~ 17 60 40 20Cruise power required ~ 35 watts 0 0 10 20 30 40 50 60 Speed ~ fpsBattery energy using current LiPotechnology at ~ 4.5 watt hours / oz and 116ounces weight; 520 W hrs.Approximate endurance ~ 15 hours vicecurrent record of 12 h 36 min Design Space for optimization •Improved L/D •Improved propulsive efficiency •Reduced wing loading •Increased battery specific energy
  13. 13. Design Space Possible Solutions ~ L/D and W/S 30 Baseline Guessed Answer Minimu Power Required @ 100% 25 L/D 20 15 efficiency 20 15 25 30 10 5 0 6 7 8 9 10 11 12 Wing Loading ~ oz/sq ft. Airspeed at CL and Wing Loading at CL = 1.0 35 30 25Airspeed ~ fps 20 15 10 5 0 4 5 6 7 8 9 10 11 12 Wing Loading ~ oz / sq ft
  14. 14. Comprehensive Performance Math Model
  15. 15. Math Model Validation ~ Motocalc Big Stardust / Aveox 450.0 400.0 Initial Climb to 400 meters (1320 ft or 1/4 mile) in 64 seconds 350.0 300.0 Descent from 400 meters 600 seconds (ten minutes)Altitude Meters 250.0 Second Climb to ensure sufficient battery energy for the SAM 90 seconds climb 200.0 150.0 100.0 50.0 Dive down to end flight 0.0 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 Time seconds
  16. 16. Weight and Balance Model 108 inch Stardust Special Texaco CG inches 7.31 Chord 11.3 * from LE CG % 0.65 Target CG Location 7.375 Weight 63.2 Wing Loading 7.9 Weight at 8 oz 63.9 Weight Location* Moment CommentsAirframe From LMR Fuselage (aveox) pushrods servos 22 5.5 121.00 less motor @ 13.5 -13.5 0 Fairings 4 7 Wing 15 4 60.00 Empenage 3 41 123.00 L/G 3 2.25 6.75 Structure 0.00 W heels 0.00 Airframe Sub total. 33.5Propulsion Texaco 0.00 Motor/ Gearboxes 4 -2 -8.00 Hacker B20-36 with 4.4:1 and 2:1 in series Nose Weight 3.5 7 24.50 Prop 2 -3 -6.00 Aeronaut 20 x 11 Spinner 1 -5.00 Motor mount 0.00 Allowable 14 cells 1500 AUL cells in 2 x 7 Power Battery 15 7 105.00 Batt W t. 15.80 parallel. Propulsion wiring 1 -1 -1.00 ESC 0 0 0.00 0 -2 0.00 Propulsion Sub total. 25.5Systems 0.00 From LMR Radio Rx 4.2 10 42.00 FMA M5 0.00 2 cell LiPoly 0.00 0.00 0.00 0.00 2 x HS 85? 0.00 Servo Mounting 0.00 0.00 Systems Sub total. 4.2Ballast 0 0 0.00 Total Weight 63.2 63.2 462.25 CG inches 7.31 CG % 0.65
  17. 17. Weight Trends1000Wing Weight ~ grams Two-Piece Wing Trend y = 0.013x1.5011100 `````````````````````````````````````````````````````````````` One-Piece Wing Trend y = 0.0076x1.5482 10 100 1000 10000 Wing Area ~ sq inches
  18. 18. Wing Design and OptimizationDesign Space•Aspect Ratio•Airfoil•Maneuver envelope •Strength •Flutter •Control authority•Flutter•Flight modes •Climb •Cruise •Dive out of thermals•Construction and materials •Experience •Tooling•Transportation
  19. 19. Advanced Wing Design The Swiss solar powered aircraft Solar Impulse (HB-SIA prototype) flies for the first time with test pilot Markus Scherdel on board at the military airport in Payerne, Switzerland, Wednesday, April 7, 2010. The prototype with the wingspan of a Boeing 747 and the weight of a small car started to a two-hour test flight to examine if the plane can keep a straight trajectory.Minimize wing bending moments by distributing propulsion and batteries span-wise
  20. 20. Build and FlySee how it is done; www.dhaerotech.com/giantblog.htm

×