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Helicopter multi engine control

SierraB

SierraB

Messages
240
Country
germany
Hello!

I'm working on the eh101-type flight dynamics for a helicopter. The two engines are working fine except I can't control them seperately.

start-up and shut-down is individually possible, BUT the throttle only controls both engines together.

BTW, the governor is inactive so I can definately control them manually...

Although I assigned one joystick lever to engine #1 and another one to engine #2 each lever always controls both engines.

Does anybody know why this doesn't work?

Best regards,
Steven
 
The EH-101 flight model uses joystick throttle inputs as collective inputs. A collective increase is treated as a throttle increase plus propellor pitch increase.

The tooltiptext_Collective says it all:
"Collective Lever (Rotor Pitch - %((A:GENERAL ENG THROTTLE LEVER POSITION:1, percent))%!d!%%, Throttle - %((A:GENERAL ENG PROPELLER LEVER POSITION:1, percent))%!d!%%)"

So the rotor pitch readout comes from the throttle position variable and the "throttle" readout comes from the prop lever position variable. The throttle controls/condition levers for the real world engines are modeled by the mixture controls for each engine. However, in this model the mixture just works as a fuel on/off lever. They do not allow individual engine control like they do in real world.

If you disable the governor, the engines will not be adjusted to control rotor RPM at 100%.

In general the governor works quite well if its PID constants are fine tuned, the stock 101 values are awful. It works well if the engines are running when the helo is selected. If you do a cold/dark start the result is very different from real world and that IMHO is the main problem with the model.

Roy
 
Thanks a lot, Roy!

So the only way I could have controled them is the mixture lever, but this one is only on/off...that's a pain.
But it just confirms what I've found out:
start-up and shut-down is individually possible, BUT the throttle only controls both engines together.
Click to expand...

I can also confirm the throttle and prop_pitch axis. But what makes me wonder is that although I assigned a prop_lever to each single engine (in the options menu), these two lever "worked as one".

Regarding the gov your right, it's acceptable when running, but it is not suitable for start-up or IDLE or...
Thats why I don't use it, set my engines manually from cold to IDLE to flight and from then at least the important torque readings control themselves :D

Steven
 
In this type of helicopter, you want all the engines to give equal power/torque to the rotor, so that is why they operate together. That part of the simulation is accurate.

Thats why I don't use it, set my engines manually from cold to IDLE to flight
Click to expand...

Ideally you would start one engine first, with the rotor brake on and run it at ground idle. Then start the second engine and release the brake, get the rotor up to speed and set the engines to flight idle. This is very hard to do in FSXA.
Roy
 
Well, the heli I'm working on has FADEC so the procedure would be: start one engine(idle), rotor at idle, start second engine(idle), rotor rpm slightly increases, set both engines to flight, rotor at 100%.

This is achieved so far. In fact it would not bother me too bad if the last step is not individually possible, because it is not often practiced in real life either.

BTW i'm talking about the ec135

Steven
 
Steven,
I think you are saying that you get 100% rotor RPM control with no governor?
Not sure how you can do that. The governor has a PID that is effective in flight and on the ground, but when it is used, the start procedure is abnormal.

The rotor brake also has a 5 second cycle and when used with the standard PID it can give results that cause the rotor to turn in a negative manner for a while, then speed up correctly.

The start set-up can be achieved using Simconnect. Start one engine with rotor brake engaged. Wait to start next engine and release brake etc.

Although autorotation is not a priority with two engines, it probably has to be achieved in case of double engine failure and that is a challenge with the 101 model.

Roy
 
Roy,
I don`t get exactly 100% , but with full collective the rpm is only around 10% lower which might be even realistic. if I wanted less reduction it could be acjieved as well. I`m using kind of fake solution, but it works brilliant so far: rotor is kept at 96-101% during flight, torque readings are proportional to rotor last, tiy depends on collective and is constant...Only the engines n1 is steady,which is the disadvantage of not using the gov.

If you watch my video (http://www.youtube.com/watch?v=u5MwJAiibDI&desktop_uri=/watch?v=u5MwJAiibDI&gl=DE),
you can see how it looks. In this old video I yet didn`t know how to control both eng so I used ctr+e. It is much better know ;)

Concerning autorotation I can either set my engines to idle or cut them individually off. Yes the rotor won`t gain/maintain rpm during descent, but there is still enough time to get the heli down safely ;)

Steven
 
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