Throttle Hold?

[Rickster]

Hi
I asaw a thread here in the last day or two - (which for some reason I can't see now for looking!) about landing with Throttle hold.

What is throttle hold - how is it used and why is it used please?

thanks

[carpman]

Heres the link , i only did a search http://www.rcheliaddict.co.uk/t-rex-...ttle-hold.html

[Rickster]

for some reason I was convinced it was in the beginners or main discussions - no wonder I couldn't find it - you'd have thought I'd have just search the lot wouldn't you!

[Rodsport999]

Throttle hold is used to cut the engine to idle speed to allow you to perform an autorotation.

Autorotation is the phenomenon which results in the rotation of and lift generation by a rotorcraft's primary rotor through purely aerodynamic forces, under certain conditions. Autorotation is employed in the normal operation of an autogyro as the primary lifting mechanism, whereas it is used in helicopters only in an emergency mode after failure of the helicopter's powerplant or transmission.
Blade regions in vertical autorotation descent.


In helicopters, autorotation of the main rotor allows a controlled descent to an emergency landing in case of powerplant failure. Proper design of the helicopter is necessary to assure that autorotation can be usefully employed, and skilled changes to the collective and cyclic pitch are necessary during the maneuver to manage the energy of the rotor and the airspeed of the craft. Autorotation depends on the maintenance of air velocity through the rotor, and during an emergency autorotation maneuver this airspeed is provided by the helicopter's descent. In autogyros, airspeed is provided by power from an airplane-type propeller which propels the aircraft horizontally; autorotation is the sole source of rotational power for the main rotor.

Here's a quick example I've found
[ame]http://www.youtube.com/watch?v=YgPXh6mtaw8[/ame]

Hope this clears the matter up!
regards

[Holst]

Another use for throttle hold is to stop you from accidentally spooling up the heli in the pits or when carrying it to the flightline.
This is probably the most important reason to have throttle hold.

Its also a good idea to hit throttle hold if you are going to crash, to prevent your heli doing a funky chicken and smashing itself up after it hits the ground.

[chopperaddict]

Hi Holst

Your point is a VERY good one, hitting the throttle hold switch before the crash happens is something so few people thionk of doing, but it can save one hell of a lot of uneccessary damage.

I must add that as a tip to my tutorial PDF's, thanks for reminding me about it.

[Steve]

I think the original intention of throttle hold was for safe startup and to disengage the engine from the blades at the clutch in the event of a mishap. Pilots using hold to do autos is an added bonus to the facility. One time when it is dead handy is in the event that you loose the tail control and the heli goes into a mental sudden death pirouette. If you can keep the heli in the air and the right way up, hitting the throttle hold will usually stop the pirouette as it disengages the engine, and the heli will weather-**** into wind, allowing you to auto it down nice and gently. It's worked a treat for me a couple of times and saved a lot of wallet-pain on contact with terra-firma.