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jobu
12-07-2005, 02:45 AM
I am messing with a build and haven't decided on 2 geared 400s or 4 direct drive 400s or 350s. The plane wiil have 48"ws and between 30+35oz fw.

Looking for better performer and how differently the performance will change from 2gb to 4dd s.

I like the look of 4 dd 400s...anyone have suggestions on either set up and if so what size props?
I will probably parralel 2 kokam1500 3s or 2 TP2100 3s 10c (old discharge rate).

Most of air frame built. Not sure on type Ju88...Mosquito... A20 or c130...b17...b29?


Thanks...Joe

Matt Kirsch
12-07-2005, 02:33 PM
Just for edification purposes, "350" is a number specific to GWS, and refers to a gear drive system. That system actually uses what we normally refer to as a "Speed 300" or "370" motor. GWS's "300" systems use a cooler wind of the 300/370 design that is not commonly used anywhere else in R/C.

Anyhoo, with the 4x400 DD setup, you'll be putting twice as much power to the propeller, though the props will be smaller and turning faster. Overall, I would expect acceleration to be about the same between the two setups, but the 4x400 DD setup will have a higher top speed if the plane is a clean design.

One thing you need to remember is that you're running twice as many motors with the 4x400 DD setup, which means the power demands are double what they would be with the 2x400 geared. Both the battery and ESC need to be capable of twice as many Amps. I'd estimate 20 Amps with the dual motor setup, and 40 with the quad. If you're going to use the quad, I'd run at least a 3P setup of ThunderPowers if you have them. 2P will be borderline, but if you're careful about throttle management, and don't need to fly around at full throttle all the time (you shouldn't considering a 35oz plane), it should be okay.

Also, using a 3S LiPoly, I would recommend a 7.2V Speed 400 motor instead of the customary 6V. The hotter motor will tend to overspeed on a 3S LiPoly, and won't last long. For props, I would recommend the customary Gunther "Zagi" props for a direct drive Speed 400.

jobu
12-07-2005, 04:31 PM
Yeah, the 4x370 looks like it my be higher mantainance, I think that the 2x400gb is a better fit with less potential problems.

While on the subject...I am thinking of a P-38 down the road and have two identical 2025 Himaxx motors/gbs. When running brushless, 2 escs are needed but do you use a Y connector before the rx? and instead of parraleling 1st do you plug a battery in each esc's battery connection as normally done?

Thanks
Joe

jobu
12-20-2005, 01:31 AM
Not really sure what to call it but something between a c130 and b25???
2 geared 400's was the choice....it flew well but is a little slow acccellerating. has 10x8x4 blades gws props any good suggestions for props? 2parralelled 1500 kokams
thanks
joe