I am hope to change twin prop drive on an old Aerokits 46" Crash Tender to brushless motors. Current drives are Graupner 820 Race motors with "Propshop" 35mm diam. 3 blade cleaver props. Would like to retain props as they are efficient but can someone with experience recommend some good inrunner brushless motors for me. Thanks in advance
Hi robhenry What volt battery are you running at present ?? 12 or 24 volts. If 24 volts those motors spec at 24,000rpm. Power is 511 Watts on 24 volts. 24,000 divide by 14.8(4S Lipo batteries) equal 1612 kv. So the closest motor would be 1700kv, eg water cooled 3660SL-1700kv which has a 5mm shaft and 44mm diameter with a length of 60mm( from Hobbyking). Power rated at 1800 Watts on 6S, so it would be lower than that. But if you are running 12 volts on the Graupner motor it would be about half the rpms. These brushless motors are far more powerful so check out the specs on the motors you are looking at !!! Canabus
Hi Canabus Thanks for your response. Very helpful. Currently the 820's are running on two 9.6v Nimh packs in series. Have not clocked amps in running conditions. I assume that I am not exceeding 20v x 20amps rated by Graupner spec sheet. Best regards Rob
Hi robhenry Your motor would be only running at about 9500rpm 0n 9.6 volts. The closest brushless motor would be a Hobbyking Turnigy L5055C-700kv on 4S Lipo batteries (10360 rpm), these are 50mm diameter, 6mm shaft. Note you require a separate ESC for each motor and a Y connector to link them to your throttle channel. Personally I would use the Hobbyking car 100A ESC's (HK-100A). Also both the motors and ESCs require no water cooling. Canabus
HI robhenry The L5055-700 are 1600watts on 8S, so only about/less than half that on 4S. I am installing only one in my crash tender with a 2 blade 52mm CNC alloy prop to start with and can upgrade later. I bought this one without running gear and single shaft. They only did 28 knots. Canabus
if you use a "y" lead to couple 2 ESCs ( or if you use 2 different channels) make sure you remove one of the red signal leads from the ESC that way you do not risk you receiver ( this presumes your ESC(s) have BEC)
"that's not a bug its just an undocumented creature."
Sir Terence David John "Terry" Pratchett, OBE (28 April 1948 - 12 March 2015)