Now that we have a running engine, how do we control it? That is also simple.

Let's start with the throttle.

It is controlled by the carburator. Itis so called carburator is no more than a mixing box. It consist mostly of a butterfly valve and a scensing system.

By moving the butterfly, thru the throttle control system, you restrict the amount of air that the engine is capable of aspirating.

Now the air/fuel mixture.

With the metering system, the carburator can add the proper amount of fuel to achive the desired fuel/air ratio. Thru the mixture control system, the pilot can "adjust" this ratio from "full rich" (the safest seting but use more fuel), to the "auto-lean" (ugually safe setting but save on fuel consumption) to the "cut off" (position to stop the engine by totaly stoping the fuel).

And the Carburator Heat.

Occasionnaly, the carburator's airways are subject to the formation of ice, disrupting the air/fuel ratio. This condition is resolved by a small "scoop" which permit warm air from the engine compartment to enter the engine airways to melt this ice formation. This scoop is controled by the carb heat control system.

For a complete interaction of these control systems just go tho the controls controls page.