I am confused
#1
Thread Starter
I am confused
I bought a used Sukhoi SU-31 electric park flyer at a swap meet. It had a Himax 2025-4200 motor with a 6.6:1 Cobri Gearbox, a 12x6 electric APC prop, and a Jeti advance 40A speed controller. I am using a 2100MAH 11.1 volt 20C cont. and 40C burst battery. It flew well enough untill I tried to take off in tall grass and the prop hit. I was going to hand launch it but as I ran up the motor the motor shaft broke at the end bell. The local hobby shop did not have a Himax in that size so I bought the E-Flight Park 400. EFLM1100.
I put this motor on and noticed that the plastic gear on the drive was worn but thought it would be OK. It also took the 12T pinon gear to match up with the spur gear on the geardrive which gave me a 5.33:1 gear ratio. As I slowly advanced the throttle in the basement everything seemed OK but when I took it out to fly the shaft and pinion went bouncing across the wing again at about 3/4 throttle. Another trip to the Hobby shop and another Park 400. Upon closer inspection I have found that the Cobri gearbox has a GWS C 64Tooth spur gear on it which is why the 12T pinon gear meshed better than the 10T. I definately need to replace the spur gear.
I have found replacement motor rotors for the Park 400 but not for the Himax. The Cobri web site that I found did not show a 10 or 12 tooth pinon gear or 64 or 66 tooth spur gears. I have spent the whole day going thru forums trying to find answers to figure out power options. Most of it makes a little bit of sense untill it comes to prop sizes and gearbox ratios.
If anybody can help put me on the right track I would appreciate it.
Steve
I put this motor on and noticed that the plastic gear on the drive was worn but thought it would be OK. It also took the 12T pinon gear to match up with the spur gear on the geardrive which gave me a 5.33:1 gear ratio. As I slowly advanced the throttle in the basement everything seemed OK but when I took it out to fly the shaft and pinion went bouncing across the wing again at about 3/4 throttle. Another trip to the Hobby shop and another Park 400. Upon closer inspection I have found that the Cobri gearbox has a GWS C 64Tooth spur gear on it which is why the 12T pinon gear meshed better than the 10T. I definately need to replace the spur gear.
I have found replacement motor rotors for the Park 400 but not for the Himax. The Cobri web site that I found did not show a 10 or 12 tooth pinon gear or 64 or 66 tooth spur gears. I have spent the whole day going thru forums trying to find answers to figure out power options. Most of it makes a little bit of sense untill it comes to prop sizes and gearbox ratios.
If anybody can help put me on the right track I would appreciate it.
Steve
#3
Thread Starter
RE: I am confused
That is an option but I have already spent 120 dollars on motors and for another 20 dollars for a rotor will have two new motors. As this is my first venture into electrics I didn't want to spend a lot more money on parts before I decide on sticking with electrics.