droggy

What exactly is throttle hold? Do I hit that switch to work on heli for checking pitch etc..?

tippy

Throttle hold is just another flight mode that has a special throttle curve. The pitch curve is the typical curve like the other flight modes. The "special" thing about the throttle hold throttle curve is that it's just one setting as opposed to a 3 or 5 or x point/setting curve. This means when you switch throttle hold on the throttle servo will go to the throttle setting and stay there ... regardless of what you do with the throttle stick.

So it "holds" the throttle at one setting but you still can move the stick and get pitch changes through the pitch curve.

What's this used for? Primarily to practice autorotations. This is when you have an engine outage in flight and you use the rotating energy of the rotor to bring the heli down hopefully without splatting. To practise this, you have to remove power from the engine so that the main rotor is no longer driven (ie engine is at idle). The use of a one-way bearing on the main shaft is how we can drive the shaft with engine power and allow it to free spin without engine power.

A secondary usage of throttle hold is for safety. When you start your heli in a flight mode (normal), if you accidently bump the throttle stick to full power ... things can get pretty exciting ... and dangerous. So, if you start your engine in throttle hold, the engine will go to idle. Now if you bumpt the stick, you'll get a pitch change but nothing else.

droggy

thanks tippy

RappyPilot

Clever trick starting a heli in throttle hold mode ... Never though of that before

Skarn

Throttle hold is FIRST and foremost a safety measure! You should ALWAYS have TH engaged prior to plugging in the heli. It's also a saftely measure for the heli....when you wreck, you should immediately hit throttle hold to lessen the damage. Preferrably, you should hit it JUST before impact, but of course that is very hard to do.

Skarn