I don't understand why these light helicopters are made to be so twitchy.

[Spacehamster]

I don't understand why these light helicopters are made to be so twitchy. This is not a complaint about the flight model, but a question about why helicopter manufacturers simply do not pre-stiffen the input (equivalent to adding a control curve or lowering the stick saturation in DCS). Because what is the point of having helicopters that are so twitchy that you can flip them over on take-off? Extra maneuverability? What for? Combat helicopters would not end up in dogfights like a ww2 plane where extreme maneuverability would be useful. They are bomb trucks that precisely move into position and fire their stuff.

[AOG]

In a sense they do. The actual cyclic and collective are much longer in the aircraft than the sticks we use. That means that for the same amount of angular deflection the actual motion required to move the stick is larger which makes it easier to add the tiny angular corrections required to keep the aircraft stable.

 

AOG

[Ramsay]

I don't understand why these light helicopters are made to be so twitchy.

AFAIK 'light' helicopters are 'twitchy' due to their small rotor discs and low masses.

 

... why helicopter manufacturers simply do not pre-stiffen the input (equivalent to adding a control curve or lowering the stick saturation in DCS). Because what is the point of having helicopters that are so twitchy that you can flip them over on take-off? Extra maneuverability? What for?

IIRC there were experimental tests to improve helicopter safety that increased the rotor mass. The increased mass/slower response improved control but in an emergency (engine failure, VRS, etc.), the lag made it harder for the pilot to respond and a 'couple of seconds' made the difference between 'life and death' in a number of air accidents.

 

Larger, heavier helicopters have similar issues due to increased response times but I believe they are mitigated by their larger rotor discs and usually more powerful engine(s), unlike a small heavy low powered helicopter.

[emko]

I don't understand why these light helicopters are made to be so twitchy.

 

In the case of Gazelle, see that there is an SAS system and an autopilot. So the manufacturer tried NOT to make it twitchy. But it's very hard to cheat the physics. ;)

[BronzeYardNo11]

In a sense they do. The actual cyclic and collective are much longer in the aircraft than the sticks we use. That means that for the same amount of angular deflection the actual motion required to move the stick is larger which makes it easier to add the tiny angular corrections required to keep the aircraft stable.

 

AOG

 

 

Not really. Your Thrustmaster Warthog is +/- 30 degrees per axis, while a real helicopter is around +/- 12 degrees (My own estimation based on various youtube videos (don't take it as a fact pls))

 

Yeah you get better control while extending your warthog, you just don't get realistic control deflections.

[NeilWillis]

Given the increased throw of our joysticks the result should be a LESS twitchy control input, not the other way round as it seems you are implying. If the Thrustmaster had less throw than the real thing, it'd be more sensitive, not the other way round!

 

If you want to get realistic control deflections, you have the option already to set the control inputs for every axis. Simply lower the saturation.

 

Given that the reason for the real thing being twitchy is low mass and low rotor mass, then what exactly is the issue being discussed, the irrefutable laws of physics are something we cannot change, so why complain about them?

[kam]

I got a 30min 'trial' flight in a Cabri G2 recently, and it really made me appreciate how twitchy the real thing is. The pilot took off, got us to 800ft then gave me control, flying and descending wasn't a problem for me but it really caught me out when we were hover taxiing to park and the speed got so low I needed to compensate with right pedal. We had wind pushing the helicopter left and almost full right pedal was needed. Skip to about 25:15 in the video to see what I mean.

 

ilmpQMS7usI?t=25m17s

[Spacehamster]

That video is great.

 

I am not wondering why small copters are so twitchy, but why they do not have more stability and dampening to counter it. Because at what point during a flight does a copter need the ability to flip itself on its head. The twitchier it is, the more a pilot has to spend training time getting used to it.

 

Note: I have never flown a real copter, I just wonder why that unnecesarry maneuverability outweighs the disadvantages of it

[Fri13]

What for? Combat helicopters would not end up in dogfights like a ww2 plane where extreme maneuverability would be useful. They are bomb trucks that precisely move into position and fire their stuff.

 

Actually the do, it is called Aerial Combat Maneuvers (ACM) for helicopters.

http://www.globalsecurity.org/military/library/report/1992/BRM.htm

 

The helicopters needs to be agile, but the thing is that they ain't so itchy as they are in simulators. In simulator you can move cyclic just couple millimeters and it can be full range of the helicopter input to flip it over. While in reality you have couple centimeters travel to have good feeling on it. They are still very sensitive for controls, but not like in simulators. And one reason for that as well is that many doesn't have a extension for their cyclic or keep it between legs.

 

Like example look the cyclic movements the trainee is doing:

[Fri13]

That video is great.

 

I am not wondering why small copters are so twitchy, but why they do not have more stability and dampening to counter it. Because at what point during a flight does a copter need the ability to flip itself on its head. The twitchier it is, the more a pilot has to spend training time getting used to it.

 

Because you are sitting in a light fuselage that has huge rotary wing above it, having all the time requirement to balance it as slight wind change or weight transfer can cause it to flip around because there is massive forces pulling forces on main rotor with gyroscopic effect.

 

You can start flying (or end up flying) helicopter so that center of gravity point is outside of the fuselage, even a meter or two. And if you don't have the capability to have range for control, you will flip over.