Trade Study 2 Motor Selection and propeller matching 1 Hadrien guepet

Conclusion from the previous trade study  We will use a propeller with a 0,7 tau ratio  The Bigger the Diameter the better the efficiency is.  A electric motor need a small propeller to avoid avoerloading your electric motor at static thrust 2

Propulsion System Battery controller Electric Motor propeller 3

brushless electric motor modelling Electric Power (Bat)  Power Diagram Controller Loss Mechanical power Copper loss due to wiring Iron loss due to hysteresis and eddy current friction 4

Comparaison between our model and experimental results KV1100 Tension3S:11,1V I02A Rext0,025 ohm Rmotor0,025 ohm After comparing 10 motors : 4% error max 5

Our Propeller : 12 x 8 APCE  Performance Chart : 6

Power required and prop efficiency for our aircraft Design point : 25° at 40ft/s Power required for the propeller : 8210 rpm 7

Motor matching  According to our model a motor with a KV of 977 will match perferctly exactly  The closest possible choice is a 1000KV motor  We choose The Turnigy SK KV  (the smaller SK 3542 could fit but we want to be sure it 8

Selected motor  Turnigy Aerodrive SK KV 9 KV1050 Tension3S:11,1V I02A Rext0,025 ohm Rmotor0,025 ohm Weight0,391lbs I max50 Power0,75hp

Efficiency diagrams 10 Climbcruise

Aircraft performance 11 Max speed about 83 ft/s Max climb speed = 40 ft/s

Speed diagram 12 Stall Speed 20 ft/s 22,5 ft/s Speed for max angle of climb (33°) 40 ft/s Choosen cruise speed 45 ft/s Max speed at 25° of climb 49 ft/s Speed for max Vz (19ft/s max) 83 ft/s Max speed in level flight