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Throttle and Choke Servos

A project log for Goliath - A Gas Powered Quadcopter

A BIG Gas Powered Quadcopter

peter-mccloudPeter McCloud 08/24/2014 at 14:591 Comment

Connecting a servo to throttle and choke is one of the last things to be done before the hover test.  I've been taking a look at the hardware on the engine to see what's required.

The engine user manual doesn't cover anything regarding the mechanical connections.  A bit of research on the internet hasn't shed any light on the details on the throttle plate either.  I know that the fuel solenoid is what has the electrical connection.  The lever arm attached to the fuel solenoid is likely the throttle.  That means the lower hardware where is likely the choke.  There's a few springs and connections, which don't seem straight forward. The one thing that's clear is the the vertical push rod is the only part that interacts with the rest of the engine.  If I'm going to just connect a servo, this seems like the best place and the rest of the hardware could just be removed.

If any one has better knowledge or access to a schematic on this, any inputs would be helpful.

Discussions

zakqwy wrote 08/24/2014 at 19:28 point
My guess is that the throttle has at least one heavy duty spring that pull the throttle plate closed, either when the throttle is manually retarded or if the throttle cable breaks. If you can replace the spring with something quite a bit lighter (and disconnect the throttle cable entirely), you'll be able to use a smaller/faster servo. I'd say the easiest way to understand the mechanism is the pull off the intake ducting and air filter so you can see the throttle plate more easily.

My ancient 40hp outboard motor has a (currently unconnected) solenoid-based choke. Might be easier to do that then try to use a second servo for this function.

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