1. Selecting Electric Power Setups John Hoddinott, 21 May 2015

2. Components of the Setup ●Brushless Motor ●Electronic Speed Controller (ESC) ●Battery (Usually LiPo, but could be NiCad, NiMH, LiFe, etc) ●Propeller ●Connectors/Wiring

3. Why Brushless Motors? Brushless motors offer several advantages over brushed DC motors (according to Wikipedia!): ●high torque to weight ratio ●increased efficiency ●increased reliability ●reduced noise ●longer lifetime (no brush and commutator wear) ●reduction of electromagnetic interference

4. Size Matters!

5. Why is the Setup Important? ●Performance ●Efficiency (longer flight times/smaller & cheaper batteries) ●Safety

6. Getting it Wrong!

7. Some Definitions V - Voltage (Potential Difference) in Volts (V) I - Current in Amperes (A) P - Power in Watts (W) P = V x I (Ohm’s Law) RPM - Rotations per Minute kV - RPM per Volt mAh - milliamp hours (a measure of battery capacity) C rating - A measure of the discharge (or charge) rate of a battery as a multiple of its capacity

8. My Process 1.Estimate Power Needed 2.Decide on Maximum Flying Speed 3.Calculate Ideal Thrust 4.Calculate (or Measure) Maximum Propeller Diameter 5.Select Preferred Battery Voltage 6.Find a Setup 7.Test/Check the Setup

9. Step 1 - Estimate Power Model Type or Flying StyleExample Power Range in Watts (W) per pound (lbs) Trainer/Powered Glider/Scale Light Aircraft/Vintage Mentor, Habicht, Cub, Junior 6060 - 100 Sports/Scale Warbird/Bi-PlaneWot4, Mustang, Gemini80 - 120 Aerobatic/Pattern Ship/Warm Liner Yak 54, Angel, Blaze120 - 200 3D AerobaticShock Flyer, AddictionX150 - 250 Hot Liner/Pylon RacerSpeedy, Nemesis200 - 300+

10. Step 2 - Flying Speed Model Type or Flying StyleTarget Flying Speed (mph) Trainer/Powered Glider/Scale Light Aircraft/Vintage 30 - 50 Sports/Scale Warbird/Bi-Plane40 - 70 Aerobatic/Pattern Ship/Warm Liner50 - 80 3D Aerobatic25 - 50 Hot Liner/Pylon Racer80 - 100+

11. Step 3 - Thrust How much thrust do we need to fly? Less than you might think!

12. Step 3 - Thrust to Weight Examples Aircraft (full size)Thrust to Weight Cessna 1720.28 Concorde0.373 BAE Hawk0.65 Harrier1.1 Typhoon1.07 Space Shuttle1.5

13. Step 4 - Propeller Diameter Bigger is better (usually)

14. Step 5 - Battery Voltage Use Ohm’s Law to calculate the battery voltage that provides the desired power with sensible current level. P = V x I Therefore V = P / I But what is a sensible current level?

15. Step 5 – Battery Current Capacity Battery current capacity is calculated by multiplying the pack capacity (in mAh) by the C rating. Example – a 2200 mAh pack rated to 25C can produce: 2200 x 25 = 55,000mA = 55A

16. Step 5 - Connector Current Capacity Deans - 100A XT Series - 30/60/90A EC3 - 60A EC5 - 120A JST - 3A

17. Step 6 - The Setup Using the data we now have (power, flying speed, thrust, propeller diameter and voltage) we now have all the information to find a setup that works. But how? Get on the internet and search!

18. Step 6 - Typical Motor Specs Nominal Voltage (V) LiPo Cell Count Typical Motor kV Typical Stator Diameter (mm) Typical Motor Weight (g) Typical Prop Diameter (inches) 7.421200 - 200015 – 2210 – 100Under 10 11.13800 - 140018 – 3025 – 2006 – 14 14.84600 - 100022 – 40100 – 25010 – 15 18.55450 - 70030 – 40175 – 35012 – 16 22.26350 - 55040 – 50200 – 40014 – 18 29.68250 - 30050 – 60400 – 80016 – 22 37.010180 - 25060 +600+18 - 24

19. Step 6 - Some Good Web Sources AXI Motors http://www.modelmotors.cz/index.php?page=1http://www.modelmotors.cz/index.php?page=1 Hacker http://www.hacker-motor-shop.com/?shop=hackerhttp://www.hacker-motor-shop.com/?shop=hacker Scorpion Power Systems http://www.scorpionsystem.comhttp://www.scorpionsystem.com Eflite http://www.e-fliterc.comhttp://www.e-fliterc.com Emax http://www.emaxmodel.comhttp://www.emaxmodel.com

20. Example Setup for Seagull E-Pioneer

21. Example Setup for the Yak 54 120e

22. Step 7 - Testing Physical Testing Using a Watt Meter

23. Step 7 - Testing Testing using ESC Data Logging Capabilities

24. Step 7 - Testing Testing using a Calculator Tool (e.g. eCalc)

25. Summary 1.Estimate Power Needed 2.Decide on Maximum Flying Speed 3.Calculate Ideal Thrust 4.Calculate (or Measure) Maximum Propeller Diameter 5.Select Preferred Battery Voltage 6.Find a Setup 7.Test/Check the Setup 8.Charge Batteries 9.Go Flying!

26. Thank you That's it, I'm off ohm... That’s it,I think you’ve heard Amp’le from me. I’m off Ohm...