A little plan for an R/C plane's engine.

[Joseph Kerman]

I want to be able to throttle the engine, just like a real one, but also be able to keep a steady speed when needed, like a car's cruise control.

I am thinking of an inverse gearbox, in which the power transmission switches between the two motors, thereby changing the flight mode.

Will it work? If you want to, you can try it out yourself. 

[Green Baron]

Combustion or electric ?

30 years ago we used a servo for the carburettor of a combustion engine, or a control unit (simplest way: adjustable resistor) for an electric one ...

Have things changed :-) ?

Edited September 7, 2017 by Green Baron

[magnemoe]

45 minutes ago, Joseph Kerman said:

I want to be able to throttle the engine, just like a real one, but also be able to keep a steady speed when needed, like a car's cruise control.

I am thinking of an inverse gearbox, in which the power transmission switches between the two motors, thereby changing the flight mode.

Will it work? If you want to, you can try it out yourself. 

You can adjust engine with throttle or electrical if electric engine as green baron says. An gearbox is not needed and would probably not work well 
That you need it to increase power then engine is running slow and reduce it then it run fast. 
This can be done electrical but is far easier to do with software as the electrical has to be tuned for each engine and estimated load. 

[YNM]

Jet ? Piston-propeller ?

If you mean something like constant speed propeller, then I guess the only way out is to have variable pitch.

If you mean actually "holding airspeed" like autothrottle / speed control on some full-size planes, then that's a tough call.

[munlander1]

I believe a jet engine would be easer, but it is still extremely complex.

[Kerbart]

8 hours ago, Joseph Kerman said:

Will it work? If you want to, you can try it out yourself. 

Having two engines, and a gearbox, to use only the one based on the way you want to control it (manual or with some automatic mechanism) does not sound like a  weight-optimized solution. And aeronautics is obsessed with weight.

If anything you should just have a "gearbox" for the throttle control (manual/automatic), and then some kind of feedback mechanism that can regulate airspeed.

[Nuke]

old way, use a servo to control throttle on engine, new way get rid of the engine and use a brushless. ive never heard of anyone doing a mechanical solution other than maybe variable pitch props (considered this for my hovercraft but abandoned the idea for a simpler thrust deflector).

Edited September 7, 2017 by Nuke