Herbert Graf wrote:
>      Considering the size and weight of the car safety has been one of my number
> one concerns. I actually have a few layers of safety. First off the throttle
> and brake are handled completely seperately, and both will default to a safe
> status if a pulse from the receiver isn't received in the last 60ms (safe
> for the brake being completely on and safe for the throttle being completely
> off). Aside from this the steering system will default to fully left (or
> right, haven't decided) in case of loss of contact with the transmitter, so
> if everything else goes wrong at least the thing will go in tight circles
> instead of a straight line.
>
>         I might also add a redundant kill switch with a second transmitter and
> receiver, the only problem, and this is something I was planning to ask, is
> how do you stop a gas engine remotely? I thought about disconnecting the
> spark plug but how would I do that considering the voltages involved?
> Cutting the fuel flow is a second idea but my experience with two stroke
> engines is that they keep running, without any fuel flow for at least 30
> seconds, long enough to cause damage. Anybody have a better idea? Thanks,

I missed the first part of this thread, but you keep mentioning
transmitter and servos, so I'm assuming you mean regular hobby stuff. In
that case, have you looked at PCM systems? They have a failsafe mode
that the receiver will enter when it looses the signal from the
transmitter. The failsafe simply sets all of the servos to predefined
positions. The actual positions used are user-configurable through the
transmitter. You could easily set the failsafe to shut off the engine.

Generally for R/C stuff the servo throws are configured such that the
minimum stick throw idles the engine, but if you also run the engine
trim all the way down the engine will shut off. That effectively creates
the idle-screw type behavior that someone else mentioned, while still
allowing you full throttle control for safety purposes. Not sure how it
works for magneto engines though.

At the field I fly at, non-PCM systems are forbidden for safety reasons.
If you're creating a new vehicle I strongly suggest that you use a PCM
system, not just for the failsafe but for its greater resistance to
interference as well.

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