electric fans, questios

[Airwolfie]

is this the right place for this?? :confused:

I want to know...
-if two electric ducted fans (like the GWS ones) rotate in the same direction, would that not cause oscillation of the model in one direction as per say?
-can you get contra-rotating electric ducted fans(ie. one clockwise, the other anti-clockwise? if so, where can i get them??

[BMatthews]

You're talking about torque reaction. It's more prevalent on propeller models and more so where the diameter is larger compared to the wingspan. For ducted fans the diameter is very low and the ducts have supports for the motor unit that act as flow straighteners so the effect, if any, will be very minimal in this case. I wouldn't worry about it with two or even 4 fans.

[Airwolfie]

thanx for that!!
anybody else's comments??

[raptor22]

I beleiveGWS has some 2and four fan models w/ noprobs

[Berdie]

Unless the mass of ducted fans is large compared to the weight of the rest of your aircraft then there's no real problem. Don't know if Bruce has already said this (don't exactly know what he meant by torque reaction) but the torque resulting from gyro precession of the motors should be faily weak so there's no real need to counter it by using a contra-rotating fans, a small bit of trimming would be just fine.

[Airwolfie]

thank you all for your help!!