I'm building a RC griffon, based loosely on Mark Porter's excellent plans at [link=http://www.model-hovercraft.com/]http://www.model-hovercraft.com/[/link]. I'm quite experienced at building aircraft so know the basics, but this is a new venture. Now, being based in the UK it would be illegal for me to use my 6 channel transmitter since this is on the 35MHz band. I have a 40MHz 2 channel car transmitter, so am looking to run the model with this. The throttle will work the propulsion fan via a speed controller, but I'm not sure what to do re the lift fan. The lift fan needs to operate whenever the propulsion fan is in action. I guess I only need on/off control for this, but this raises a few issues:

- If the fan doesn't need to run at full power to lift the model (time will tell...) is there a way of reducing the power without using a speed controller (obviously other than changing the motor....)

- I've had suggestions of putting a servo in tandem with the speed controller, that would flick a microswitch on and off. This switch would then control a relay which would operate the lift motor. Does this sound like a good approach

The propulsion motor will have normal / reverse (could be useful...) control. So essentially the lift motor needs to be 'off' in the neutral position. Any way of achieving this using some electronics rather than the above?

Any thoughts/comments welcome - I can't find anything the web re this.

Thanks - Richster

I sent you a PM

It is going to be difficult to operate a hovercraft wth two channels only, really need three for thrust , rudder and lift fan but you could use a Action Quadswitch to swtch the lift fan on and off by pulsing the rudder stick. This would be better than a micro switch on the rudder, tendency is to switch off when turning if not very careful. The lift fan motor would be direct feed from battery possibly via a relay if the amperage is too high for the switch. If you need to throttle the lift motor , try Maplins voltage regulator RN41U (£14.99)