Engine Instrument Question.

[bradmick]

So, I did some fam flying in the Black Shark yesterday and this morning, definately going to take a little getting used to, as she flies a little differently then i'm used to. My biggest question is this, as a US aviator, i'm used to looking at Torque. Torque tells me everything, I pull in this much torque and i'm going to go this fast. I pull this much torque and i'm going to hover at 5 feet, or 80 feet. But I always know that number and am able to reference it. In the Black Shark i've got Rotor Pitch, Engine RPM, and EGT. Which of those three is going to give me a correlation to a set Cruise Speed, or Hover Power? As with my example, at a set gross weight i'll have to pull say....54% torque to maintain 110 KTAS.

 

Appreciate it!

 

Brad

[press]

Rotor pitch.

[deephack]

Hi People,

 

Sorry Press but I don't think thats what Bradmick is looking for as the rotor pitch will remain constant no matter how much effective power the engine is producing. Now keeping in mind I'm a PPL pilot and as such have no real world experience with a machine this complex I think you are after either the EGT gauges on the right of the front panel or the engine power indicators on the wall panel.

 

Neither of these will be exactly what you are used to but I think the engine power indicator is as close as you will get to a torque indicator. It actually measures air pressure at the compressor outlet but that should be a good gauge of the power being produced. The only problem with it compared with a torque readout on an Apache is the scale is a little hard to read accurately.

 

Still should do the trick.

[nemises]

see...as a non pilot, I just keep my eye on the VVI and PAI and blag it with adding / dropping collective..

...guess that wouldn't cut it in the real world though :( ..

 

Now that I know such a requirement exists for piloting accurately, I hope someone can explain the equivelant in the shark! :)

 

If EGT is it, I'd better start paying more attention to it!

Edited December 18, 2008 by nemises

[ryuzu]

Well on the right hand wall console on the top there is an engine power indicator - it has marks for Takeoff, max continuous and cruise engine power settings.

 

Rotor Pitch is more easily readable and the one I'd use - assuming the helicopter is functioning properly (i.e. the governors are working, the FCLs are set to auto etc) then a particular pitch setting is going to generate a fixed amount of lift in a given situation. So for a given mass and environment, the helicopter will hover with a given rotor pitch.

 

Someone else mentioned EGT - that might work in pistons (although I doubt it with helicopters) since they're relatively low temperature but in a turbine helicopter with temperatures in the high hundreds of degrees, the change of temperature in the 10s for different power settings is too small to read on the gauge and too inaccurate for power setting purposes.

 

r.

[ryuzu]

see...as a non pilot, I just keep my eye on the VVI and PAI and blag it with adding / dropping collective..

...guess that wouldn't cut it in the real world though :( ..

 

Now that I know such a requirement exists for piloting accurately, I hope someone can explain the equivelant in the shark! :)

 

If EGT is it, I'd better start paying more attention to it!

 

Well, the above approach (pull power to meet requirements) is fine until you get to somewhere moutainous - can you clear the mountain ahead? Only way to be sure is to see how much power is available to you. Conversely, you want to approach a target but you're upwind of it meaning you need to come to a hover (or at least slow flight) while going downwind and out of ground effect - will you be able to or are you going to risk of yaw control and/or vortex ring state?

 

There are lots of very good reasons you try and know these things in the real world - in a sim, if you overstress the aircraft nothing happens. In the military if you overstress the aircraft, you probably get chewed out and possibly killed (in the Civilian world if you overstress the aircraft you possibly kill your pax and yourself and you potentially lose your job!).

 

So it is important, but this is only a sim so pull away :) I guess the logical next question is how can you know how much power you have in hand and how much do you need in various scenarios? That will take more testing than I've done in the Sim to work out the BS performance - I imagine it's something KA50 pilots have various rules of thumb for.

 

r.

[deephack]

Hey ryuzu, like I said I could well be wrong but I don't think the rotor pitch is useful in this respect as it is purely a product of how much collective you are pulling. It doesn't take in to account airspeed, pitch, roll, altitude, temperature, engine state etc etc.

[ryuzu]

Hey ryuzu, like I said I could well be wrong but I don't think the rotor pitch is useful in this respect as it is purely a product of how much collective you are pulling. It doesn't take in to account airspeed, pitch, roll, altitude, temperature, engine state etc etc.

 

Well, yes, I think you are wrong.

 

Not because you're incorrect about EGT, but because it is not a suitable instrument for a pilot to use for performance prediction. In a turbine helicopter EGT will show a range of 0 degrees C up to somewhere around 1000 degrees C. Going from ground to hover will require a temp. change of around 50 degrees C - the movement on the already small EGT guages is too small to be useful to the pilot and that is for a major change from ground to hover - cruise changes will be smaller still. Finally, the EGT indication will not advise you of over pitching or overloading the transmission system.

 

To put it another way, if I see any significant movement on the turbine outlet temp gauge during any phase of flight, I'm expecting something bad to happen with that engine and thinking about a precautionary landing.

 

In lieu of a TQ meter, Rotor pitch and the engine power indicators are the primary performance instruments.

 

r.

[deephack]

Sorry I think I was unclear in my post, I was actually recommending the use of the engine power gauge not the EGT gauge. You are of course totally correct that the EGT is useless due to the small changes in it's readings.

[RvETito]

As far as Kamov helicopters (with TV3-117VMA engines) are concerned the available and current power is estimated from the gas-generator RPM, EGT and engines power indicator. Pitch no, nowhere in the flight manual it's mentioned as contol parameter. One simple example to illustrate it- with the same weight you'll need bigger collective pitch to hover at 1000m compared to 0m (excluding the RIG effect).

 

Few words about the engine power indicator. The yellow marks indeed move up and down as a function of the comrpessor outlet pressure and what the indicator actualy measures is the compressor's presusre ratio. The position of the red index in the middle with the take-off, max continuous and cruise marks is controlled automaticaly as a function of the ambient temperature and static pressure. That's why it is the most accurate instrument to estimate the current and available power- it takes into account the outside conditions to calculate the max cruise, max contrinuous and take-off marks.

 

Another very important indication are the amber lights ENG PWR LIMIT on the overhead panel- when they lit up that means the EEG has reached the treshold of it's software and it's limiting the engine power either by GG RPM or EGT, whichever occurs first. The EEG aslo gets ambient temperature and static pressure to calculate it's treshold (the maximum GG RPM for the given conditions, the EGT is fixed to 985+-5'C). So when you see those lights to illuminate you should know that further increase of collective will cause rotor RPM drop since the engine power is electronically limited.

[AlphaOneSix]

Where I work (we fly the Mi-17), we put tape over the EPR gauge (the power gauge above the battery switches) and only use EGT for performance limitations. You can easily tell EGT changes as small as 5 degrees. It's also easy to get used to what the EGT will be when you're hovering, when you're cruising, etc. As an example, we tend to cruise at about 860 degrees EGT (well, PTIT on Mi-17). Whatever that gives us in terms of airspeed, then that's what we get.

 

Brad, with regard to your question, the Russians just don't think that way (in terms of torque required to do things). They have EGT and EPR limits. The EPR limits are right on the gauge, the bottom red mark is your power limit for cruise, the middle one is for max continuous power, and the upper one is takeoff power. The EGT limits are specified in the flight manual for regimes such as cruise, takeoff, OEI, etc. Also, very unlike U.S. military aircraft, the rotor and engines don't spin at 100%, you want your rotor at 95% and your engines will be around 93% in cruise.

 

In other words, in the game, your best bet will be to use your EPR gauge and maybe correlate your blade pitch to certain regimes, such as saying it takes 10 degress of blade pitch to maintain an IGE hover with your typical combat load. Me, i tend to look at the pitch indicator pretty offen, although I don't do anything with te number I see. If you're cruising along and you EPR gauge is up around the takeoff power mark, the engines will be failing soon, so I'd say the EPR gauge is your best bet, although you won't get anything like you're used to with a torque reading.

Edited December 18, 2008 by AlphaOneSix

[RvETito]

Yeah, that kinda differ from aicraft to aircraft. In the Mi-17 for example you have the EMI-3 3-needle indicator with the top needle indicating nozzle fuel pressure while in Kamov helicopters this is not used and this sector is painted black. The UR-117V power indicator thouhg is all the same for all helicopters powered by TV3-117.

[Prophet]

OK, this thread is worthless without pictures!

 

:music_whistling:

[bradmick]

Where I work (we fly the Mi-17), we put tape over the EPR gauge (the power gauge above the battery switches) and only use EGT for performance limitations. You can easily tell EGT changes as small as 5 degrees. It's also easy to get used to what the EGT will be when you're hovering, when you're cruising, etc. As an example, we tend to cruise at about 860 degrees EGT (well, PTIT on Mi-17). Whatever that gives us in terms of airspeed, then that's what we get.

 

Brad, with regard to your question, the Russians just don't think that way (in terms of torque required to do things). They have EGT and EPR limits. The EPR limits are right on the gauge, the bottom red mark is your power limit for cruise, the middle one is for max continuous power, and the upper one is takeoff power. The EGT limits are specified in the flight manual for regimes such as cruise, takeoff, OEI, etc. Also, very unlike U.S. military aircraft, the rotor and engines don't spin at 100%, you want your rotor at 95% and your engines will be around 93% in cruise.

 

In other words, in the game, your best bet will be to use your EPR gauge and maybe correlate your blade pitch to certain regimes, such as saying it takes 10 degress of blade pitch to maintain an IGE hover with your typical combat load. Me, i tend to look at the pitch indicator pretty offen, although I don't do anything with te number I see. If you're cruising along and you EPR gauge is up around the takeoff power mark, the engines will be failing soon, so I'd say the EPR gauge is your best bet, although you won't get anything like you're used to with a torque reading.

 

 

Wow, that's just wickedly over complicated for no good reason by my thinking, but interesting. Any reasoning behind why Torque isn't used? By my thinking it simplifies things by giving me a single number and point of reference to keep in my head.

 

It's also really cool to see how a non western country (from what i've seen and read torque seems to be a pretty standard measurement for western countries aircraft) goes about doing things. It'll definately take a little bit of getting used to in flying the sim, a challenge I welcome :)

 

Brad

[tusler]

Thanks for serving!

 

Wow, that's just wickedly over complicated for no good reason by my thinking, but interesting. Any reasoning behind why Torque isn't used? By my thinking it simplifies things by giving me a single number and point of reference to keep in my head.

 

It's also really cool to see how a non western country (from what i've seen and read torque seems to be a pretty standard measurement for western countries aircraft) goes about doing things. It'll definately take a little bit of getting used to in flying the sim, a challenge I welcome :)

 

Brad

Hi Sir,

Having spent some time in H53's I too am lost without torque indications.

Thanks for your service! Now you could do many of us a big favor and put together some guides on non-radar combat helicopter tactical procedures to help us stay alive in BlackShark:joystick:

[bradmick]

I'll have to see what I can do. :)

 

Brad

[sobek]

Another very important indication are the amber lights ENG PWR LIMIT on the overhead panel- when they lit up that means the EEG has reached the treshold of it's software and it's limiting the engine power either by GG RPM or EGT, whichever occurs first.

 

So that means that the EEG will essentially keep you from overstressing the engines, or will they degrade, if you run them on the limit for a longer period (talking about the game here of course)?

[AlphaOneSix]

Any reasoning behind why Torque isn't used?

 

I have a bunch of guesses, but I really don't know. Maybe AirTito knows! :helpsmilie:

[sobek]

I have a bunch of guesses, but I really don't know. Maybe AirTito knows! :helpsmilie:

 

Is'nt torque measuring equipment rather complicated? I mean a dynamometer is not appropriate, given that it absorbs all the power that the engine produces. :) I would guess that it is measured by torsion of some drive-train part, which i imagine would be rather complicated.

 

Edit: Well i just read a little and have found, that torque measurement works indeed with strain gauges, which is not that difficult to realise but may be too fragile for russian military doctrine(?).

Edited December 19, 2008 by sobek

[Mugatu]

So if i've pulled on the collective and the warning lights are lit, I can continue pulling and I won't blow the engines? I've always dropped the collective a bit when it happens.

Edited December 19, 2008 by Mugatu

[Slayer]

Real pilots fly on gut instinct IMO :P When you are flying towards the mountains in this sim you can pretty much sense if your going to make it over or not. After flying this for a while you start to subconciously learn the limits of what can and cannot be done with the helicopter.

[sobek]

Real pilots fly on gut instinct IMO :P When you are flying towards the mountains in this sim you can pretty much sense if your going to make it over or not. After flying this for a while you start to subconciously learn the limits of what can and cannot be done with the helicopter.

 

I can hardly imagine that, given alone all the athmospheric factors that come into play. Add your own weight (of the aircraft, of course;)) and the possibility of icing to your equation and i'm sure you won't be able to anticipate the flight envelope properly without doing some basic calculations.

Edited December 19, 2008 by sobek

[RvETito]

So that means that the EEG will essentially keep you from overstressing the engines, or will they degrade, if you run them on the limit for a longer period (talking about the game here of course)?

 

Yes, the EEG is only to protect the engine from overstressing- limiting maximum compressor RPM, EGT (together with the EGT electronicgovernor) and power turbine protection (it shuts down the engine in case of power turbine (rotor) overspeed). IRL the operation at take-off and maximum continuous power are limited for the TV3-117VMA - 5% from the TBO for take-off, 40% from TBO for max continuous. The book also says that you must operate no more than 6min continuously at take-off power from 2 engines. In OEI there are different modes and power limits- 2.5min mode which is also called emergency power (2400hp) and 30min mode which is actualy the take-off mode power(2200hp). For the moment in BS, there is no overstressing of the engine operating at take-off power.

 

I have a bunch of guesses, but I really don't know. Maybe AirTito knows!

 

Torque measuring system is not so complicated to design. All russian turboprop engines have it. It represents an oil manometer and the torque is measured in bars. However, russian turboshaft engines don't have it. As for why is that, I can't really say, I would rather guess it's more a matter of design philosophy. Perhaps because of the operational time limits at take-off and maximum continuous power which are given in h.p. The marks on the red index of the engine power indicator correspond to exact value in h.p.

[McVittees]

Bradmick: don't know if you've seen this post by Wags, but being a trainee Apache piolet I think you'd be a good canditate to reply to it:

 

http://forums.eagle.ru/showthread.php?t=31840

[sobek]

Torque measuring system is not so complicated to design. All russian turboprop engines have it. It represents an oil manometer and the torque is measured in bars. However, russian turboshaft engines don't have it. As for why is that, I can't really say, I would rather guess it's more a matter of design philosophy.

 

I'd be intrigued to find out how that works :) Do those turborpop engines feature a torque converter? Maybe the system was deemed too heavy for helicopter use. I always thought the measurement would work with strain gauges, but these are probably hard to manufacture so that they withstand the vibration levels.