Use throttle or rpm engine governor switch?

[Nooch]

Hi everyone!

 

Which one should I use to change my engine rpm, the throttle (twist grip on the collective) or the governor switch (also on the collective)? They seem to both do exactly the same thing...

I've just done some research on the topic but can't find any good clear answer to the question. Thanks for the help!

[Socket7]

Set your throttle to maximum, then use the governor for fine adjustments.

 

You should only be managing rotor RPM with the throttle if the governor fails.

 

Edit: Found some excerpts from the flight manual that explain things.

 

C. Governor switch

The GOV switch is located on the ENGINE control panel. AUTO position permits the overspeed governor to automatically control the engine rpm with the throttle in the full open position. The EMER position permits the pilot or copilot to manually control the rpm. Because automatic acceleration, deceleration, and overspeed control are not provided with the GOV switch in the EMER position, control movements must be smooth to prevent compressor stall, overspeed, over-temperature, or engine failure.

Note. If GOV switch is in EMER position and throttle is full opened, main rotor rpm can exceed the limit, so pilot should control engine and rotor rpm manually by rotating the throttle twist grip.

 

2.4.4. Governor RPM Switch

The pilot and copilot GOV RPM INCR/DECR switches are mounted on a switch box attached to the end of the collective pitch control lever (Figure 4.6). The switches are a three-position momentary type and are held in INCR (up) position to increase the power turbine (N2) speed or DECR (down) position to decrease the power turbine (N2) speed. Electrical power for the circuit is supplied from the 28 VDC essential bus and is protected by a circuit breaker marked GOV CONT.

Edited December 29, 2014 by Socket7

[Nooch]

Ok so the throttle is there mainly as a backup and should normally remain set to the maximum.

When do you need to adjust the turbine rpm? I do not see why one would want to set it lower than near full speed while in the air. Except maybe for minor fuel savings... I don't know, I'm still a helicopter noob lol

Edited December 29, 2014 by Nooch

[TXSailor]

Ok so the throttle is there mainly as a backup and should normally remain set to the maximum.

When do you need to adjust the turbine rpm? I do not see why one would want to set it lower than near full speed while in the air. Except maybe for minor fuel savings... I don't know, I'm still a helicopter noob lol

 

My understanding, in ANY of the helicopters, don't touch an RPM governor at all, unless you have some kind of failure of the main system. The engine is designed to run at full throttle, and manage itself.

[Socket7]

I don't know, I can't find any documentation on the governor switches use. It allows you to set the turbine RPM. In addition to changing the Rotor RPM, this also has an effect on engine EGTs.

 

I guess the governor switch is used as part of thermal management. I think it also has some effect on load capacity, since you have to turn the governor off for heavily loaded takeoffs.

 

I'm really just guessing though.

[iFoxRomeo]

Set your throttle to maximum, then use the governor for fine adjustments.

 

You should only be managing rotor RPM with the throttle if the governor fails.

 

Edit: Found some excerpts from the flight manual that explain things.

 

C. Governor switch

The GOV switch is located on the ENGINE control panel. AUTO position permits the overspeed governor to automatically control the engine rpm with the throttle in the full open position. The EMER position permits the pilot or copilot to manually control the rpm. Because automatic acceleration, deceleration, and overspeed control are not provided with the GOV switch in the EMER position, control movements must be smooth to prevent compressor stall, overspeed, over-temperature, or engine failure.

Note. If GOV switch is in EMER position and throttle is full opened, main rotor rpm can exceed the limit, so pilot should control engine and rotor rpm manually by rotating the throttle twist grip.

 

2.4.4. Governor RPM Switch

The pilot and copilot GOV RPM INCR/DECR switches are mounted on a switch box attached to the end of the collective pitch control lever (Figure 4.6). The switches are a three-position momentary type and are held in INCR (up) position to increase the power turbine (N2) speed or DECR (down) position to decrease the power turbine (N2) speed. Electrical power for the circuit is supplied from the 28 VDC essential bus and is protected by a circuit breaker marked GOV CONT.

 

My understanding, in ANY of the helicopters, don't touch an RPM governor at all, unless you have some kind of failure of the main system. The engine is designed to run at full throttle, and manage itself.

Totally right!

 

I don't know, I can't find any documentation on the governor switches use. It allows you to set the turbine RPM. In addition to changing the Rotor RPM, this also has an effect on engine EGTs.

 

I guess the governor switch is used as part of thermal management. I think it also has some effect on load capacity, since you have to turn the governor off for heavily loaded takeoffs.

 

I'm really just guessing though.

You found the explanation. Why this guessing now. That guess is wrong. Especially the part with "you have to turn the governor off for heavily loaded takeoffs". This "thinking" came with the Elbrus mission and is total nonsense. So please eradicate it from your memory.

 

Fox

[Socket7]

If you weren't EVER supposed to touch the turbine governor why would it be in the helicopter at all?

 

Obviously, there is a situation that it is used.

 

The information from the manual just tells you what it does, not why it is used.

 

Do you have any insight on this what situations the RPM governor control switch is used? Or are you just telling me I'm wrong?

[Buzzles]

I think people might be not entirely explaining which switch they are referring to, as there are two in play in the Huey:

 

 

A) Switch on center console with the red triangle cap. This is the Governer Auto/Emergency switch.

 

You leave this at Auto and the collective throttle at full for all of your flying unless the governer system is broken.

If it is broken, then you flip this to the Emergency setting (which disables the governer) and use the collective throttle to control the engine RPM and by extension: the rotor RPM.

 

B) The silver/grey Governer RPM three way momentary switch on the top of the collective.

 

This is used when the Governer is in AUTO mode. This is effectively for controlling rotor RPM. Functionally this is very similar to the RPM lever in the P51. Think of it as setting your desired rotor RPM target and that the governer will then adjust the engine RPM to try and match the setting.

 

You can play with this as much as you want during normal flight, although I don't really find a need to at the moment as the Huey still doesn't have EGT overtemp modelled. As far as I remember, if you've turned the governer off, this switch is non functional.

 

(Note, these are functional descriptions, not technical, and I've avoided mentioning the effect the collective itself has on both RPMs)

 

Hope that helps.

 

TL;DR:

Don't touch red triangle or collective throttle under normal flight conditions leave in auto and full, but feel free to use the silver three way switch.

If something has gone nips north. Flip the red triangle to emergency and use the collective throttle. Ignore silver switch.

Edited December 30, 2014 by Buzzles

[HuggyBear]

To clarify a little, the Gov RPM 'beep' switch directly affects the N2, which in turn affects the NR.

 

Also the beep switch isn't for EGT management. If you find the EGT approaching limits, manage your collective/torque setting to protect the engine.

 

The beep switch is there because a real UH-1H is not a precision instrument and does not have FADEC.

 

Despite the excellent work of the engineers a UH-1H governing system will often have a little droop, either positive or negative, and the N2 will wander from 6600 with different torque settings and even different environmental factors.

 

For example, after setting N2 to 6600 during start, then lifting to the hover (thereby placing load on the system), it is not uncommon to find that the N2 has positively drooped and is now sitting at 6400. The beep switch is then used to trim the N2 back up to 6600.

 

The N2 will likely not wander too much throughout the flight, but will probably negatively droop to a higher setting when on the ground with no power applied. The N2 can be beeped back to 6600 on the ground but most pilots won't care as a slightly high N2 on the ground won't cause damage and it's easier not to have to beep back up as you pick up to the hover again.

 

Ideally the governors and droop cam would keep everything perfectly trimmed, but the old girl was built in simpler times so the beep switch is a simple and effective countermeasure.

 

When in maintenance the engineers and maintenance pilots will try to eliminate any droop but you wouldn't ground an aircraft for a little droop unless it was causing a real problem.

 

Modern helicopters usually have FADEC which will do all the work for the pilot and keep things at 100%.

 

The DCS UH-1H is a far more reliable girl than the real one, so the beep switch isn't really of much use, except to beep the N2 nice and high when more power is required, however you should then reach your torque/EGT limits earlier and negate much of the benefit.

 

Hope that helped, feel free to ask for clarification.

 

- Bear

[iFoxRomeo]

Set your throttle to maximum, then use the governor for fine adjustments.

 

You should only be managing rotor RPM with the throttle if the governor fails.

 

Edit: Found some excerpts from the flight manual that explain things.

 

C. Governor switch

....

 

2.4.4. Governor RPM Switch

....

 

You explained what these switches are for.

There is no need for guessing here.

 

I don't know, I can't find any documentation on the governor switches use. It allows you to set the turbine RPM. In addition to changing the Rotor RPM, this also has an effect on engine EGTs.

 

Documentation should be in the flight manual you used for your previous post.

 

I guess the governor switch is used as part of thermal management. I think it also has some effect on load capacity, since you have to turn the governor off for heavily loaded takeoffs.

 

That is what I wanted to say: Eradicate this procedure from you memory. It is completely wrong.

 

I'm really just guessing though.

 

If you weren't EVER supposed to touch the turbine governor why would it be in the helicopter at all?

 

Obviously, there is a situation that it is used.

 

You have to use the Governor switch in case of governor failure to switch the governor off. Or for training of a governor failure.

Other than that keep it in the AUTO position all the time. No other case there for switching the governor off.

No heavy load thing.

 

As Buzzles and Huggybear said: Governor RPM Switch is for fineadjustment of rotor(loaded)/turbine(N2) rpm. N2 continuous operation within 6600rpm and 6400rpm.

6400rpm is recommended to reduce vibrational stress on the rotorhead during cruise flight.

But 6600rpm is recommended for hot and high environment and/or heavy loads during take off and landing. The difference here is not that you can carry more, but the really weak tailrotor gets some more rpm to produce more thrust.

 

The information from the manual just tells you what it does, not why it is used.

The manual should tell you when and why most things in the helicopter are used. Did you use the DCS manual or the real one? Didn´t look intensively into the DCS one.

 

Do you have any insight on this what situations the RPM governor control switch is used?

 

Yes I have. See above.

 

Or are you just telling me I'm wrong?

You unfortunately got the wrong information either from some forum or the "Elbrus" mission.

 

Sorry Socket7 when I sounded rude to you in my previous post. It wasn´t meant to be so. But that "heavy load-> switch the governor off" thing is just total nonsense and is so persistend in the community´s mind. I didn´t want it to be uncommented, but was too sloppy in my writing.

 

Fox

[Frostregen]

So how do you manage a heavy load take off then?

Max out rotor rpm with 3-way-momentary switch?

Or simply accellerate in GE until TL takes over?

 

I "learned" this gov-emergency stuff from UN-Pilot campaign. (And even put this switch on my G940 setup.) Stupid mission ;)

 

UPDATE:

Sorry, did not read this:

-6400rpm for cruise flight

-6600rpm for heavy take off

Edited December 30, 2014 by Frostregen

[iFoxRomeo]

So how do you manage a heavy load take off then?

Max out rotor rpm with 3-way-momentary switch?

Or simply accellerate in GE until TL takes over?

 

I "learned" this gov-emergency stuff from UN-Pilot campaign. (And even put this switch on my G940 setup.) Stupid mission ;)

 

If there were some kind of damage modeled for the rotorhead and engine due to overspeed then it would make sense to have this switch easily accessible. But for now it is only necessary if you train governor failures.

 

UPDATE:

Sorry, did not read this:

-6400rpm for cruise flight

-6600rpm for heavy take off

 

That is good. My personal recommendation would be:

-6400rpm for cruise flight

-6600rpm for everything else except cruise flight

that way you stick to the safe side

 

 

Fox

Edited December 30, 2014 by iFoxRomeo
text added

[Socket7]

Thank you for the information on what the governor RPM switch is used for!

 

Sorry for being a bit rude.

 

Switching the governor to emergency mode for anything other then a governor failure has been duly deleted from my list of proper procedures.

[HuggyBear]

So how do you manage a heavy load take off then?

Max out rotor rpm with 3-way-momentary switch?

Or simply accellerate in GE until TL takes over?

 

I "learned" this gov-emergency stuff from UN-Pilot campaign. (And even put this switch on my G940 setup.) Stupid mission ;)

 

UPDATE:

Sorry, did not read this:

-6400rpm for cruise flight

-6600rpm for heavy take off

 

For realism, leave the N2 at 6600.

 

Beeping up will reach an engine limitation (TQ/N1/EGT/NR droop) sooner.

 

Accelerate to ETL in ground effect or offload cargo. In the real aircraft you can't help

anyone by crashing or breaking your aircraft, unfortunately the sim doesn't provide this aspect.

 

Beeping down in the cruise will require more TQ to compensate, negating any fuel flow saving. You also risk forgetting to beep back up during an approach.

 

Having said all that, it's just a sim so you can do what you like. :)

 

For realism, leave the N2 at 6600.

 

- Bear

Edited December 31, 2014 by HuggyBear
Corrected 'aim' to 'sim'

[Frostregen]

Thanks for the information :)

[iFoxRomeo]

...

 

For realism, leave the N2 at 6600.

 

...

So reality changes with the operator... Interesting:D:D

 

Frostregen I suppose you´re from Germany?! Use the German Air Force skin, then 6400N2 is also real.

 

Fox

[HuggyBear]

My apologies, I didn't realise some operators still used 6400. :)

 

Is there a reason apart from the suspected fuel flow savings?

 

The ADF also used to use 6400 in the cruise but abandoned it several years ago due to the reasons I mentioned.

 

Cheers,

 

- Bear

[DSPALLASVI]

For realism regarding EGT, maybe this thread might help a little:

 

http://forums.eagle.ru/showthread.php?t=142452

 

DSPALLAVI