First G to E Help please

[Magnumeng]

Since the plank guys have not helped out yet, I come to the faithful rotor heads.

This will be my first G to E converstion so be nice.

This will be a direct drive system swinging about a 9x4 - 10x4 prop.

Plane: Lanier Ripper
Plane weight: 2.5-3 lbs
Motor: Align 430L Brushless Outrunner 3550Kv
Speed contol: 35A (Not sure which one yet)
Battery: 2100 3cell Lipo 16-25C

Am I way off with my set up?

[mike5334]

I'm at work at the moment. As soon as I get home though, I'll plug the numbers into MotoCalc and see how it looks.

At first glance though, it looks like it'll pull a lot of amps. Base motor rpm on that 3 cell is around 39K (3550kv x 11.1v). Thats high for a direct drive propeller setup. Perhaps a lower Kv motor or a 2 cell lipoly might be better. Again, I'll be able to try some options when I get home after work.

[Magnumeng]

Thank you for your reply. I can alway count on the rotor heads to help me out.

[mgg1]

I have a direct drive Align 430L with an Align 35 amp esc turning a 5x3 3 blade prop turning 19500 rpm with a 2500 3s 25c.
It is on a Goldberg Gentle Lady glider which is a little over 2 lbs ready to fly.
Very pleased with the performance and flight duration compared to a .061.
It will take off and climb at a little over half throttle.
The motor runs very warm at full throttle with the 5x3 for more than a brief period of time.
To use a 9x4 you will probably need a gear reduction unit on the motor to keep it from over heating due to the high current draw.

[Magnumeng]

Sounds like i am going to have to go with a different motor or through a .15 on the front.

This just gives me more reasons to put together that other TRex I have.

[mike5334]

Ok. I finally managed to run some numbers through Motocalc.

The combo you have would pull a whopping 55 amps turning the 9x4 prop at 11.3K rpm. The amp draw would not only blow the esc but melt the battery pack down. heh.

Playing with diffrent motor conbos, it looks like a motor with around 1500 - 1700 kv would work nicely with the battery/esc combo you have. The Great Planes 35-48-1600, 1600 kv motor gave us a 34.8 amp draw at full throttle on the 9x4 prop, 42 oz of thrust, and 310 watts (100 watts per pound is very good).
If you used the Axi 2814/10, 1640 kv motor, it would draw 34.5 amps, 44 oz of thrust, and 349 watts.

Both of those power combos would be straining your battery at full throttle. If you kept the 2100 mah pack, it would need to be a 15C or better to prevent puffing. A 20C pack should work nicely.

[Magnumeng]

Thank you for the info... I def do not want to burn up my packs since they are my TRex pack. Guess I will go get a engine and a gallon of gas.

Will look into a speed plane for the align motor.