Are LH/RH Lim lit up with overtorque or reaching the point right before?

[Reticuli]

My rear throttle detent is a nice spot for when they first come on intermittently. The slightest amount backed off that and they never light up. Is that over torque or about to over torque at the detent with these intermittent? Are the warning lights triggered by over torque or by reaching safe limit?

[msalama]

Core RPM overspeed will trigger them IIRC, not 100% sure however.

[-MadCat-]

The yellow lights are mere indications for that the EEG is limiting the corresponding engine so it does not over-speed or step over other limitations

(cumbustor nozzle temperature e.g.).

 

Engines are operating at the limits, don't worry too much about it as long as you don't make it a habit.

It's ok for short periods of time when you really need all the power to get over a mountain or the like, while staying within (mostly) safe engline limits.

 

Flying at the limits for a prolonged time however, is not recommended !

 

Greetings

MadCat

[ShuRugal]

Flying at the limits for a prolonged time however, is not recommended !

 

 

That said, I've flown my KA-50 at govenor limits continuously for over an hour with no ill effects.

[Dr_Arrow]

That said, I've flown my KA-50 at govenor limits continuously for over an hour with no ill effects.

 

Probably this doesn't matter in the game, but in real life you decrease the service life of the engines and their components considerably...it can be as much as 1 second of operation at limits takes 5 to 10 seconds of service life or even more.

[Isegrim]

Flying the Ka-50 with Govenor lights on = Damage within 5-90 Minutes IIRC.

[Flagrum]

Probably this doesn't matter in the game, but in real life you decrease the service life of the engines and their components considerably...it can be as much as 1 second of operation at limits takes 5 to 10 seconds of service life or even more.

Is that really so? Or rather, does that really matter that much? I mean, if I fly always at 100%, the governors prevent me from going to 101% or more, then I reduce my service life of 5 hours per flight hour.

But if I would just fly at 99% all the time, all would be fine? Wouldn't it be rather that in this case I would reduce the service life by i.e. 4.75 hours per flight hour?

 

What I try to say is, the service life is an estimated value based on some "average" flying characteristics. With higher average strain on the engine, the wear rises exponential, allright, but as long as the engine is operated within it's defined limits (and the governors are ensuring that), everything is fine, no? There is no "technical order" that specifies that flying at 100% must be resticted to 10 minutes max or something like that.

 

Yes, there is a reason why the cruise speed and the max speed are not the same, but if I need to get fast to some place, then I fly fast - we are at war after all! :o)

 

edit:

Flying the Ka-50 with Govenor lights on = Damage within 5-90 Minutes IIRC.

If that is true, then there IS some sort of "technical order"? Where did you read that - the manual?

[Isegrim]

Sorry what i have written is not correct.

 

The transmission is made to run 5-30 minutes without oil.

 

The *LH/RH set Lim* indication lights only shows that the *EEG* has limited the torque of the Engines to maximum after overtorgue.

 

So this should not have a big effect to the engines.

But if you give them to much (the Rotorblade angle will increase more cause it isnt limited via the *EEG*), the transmission can get damaged after a while.

 

Edit: Madcat did write this already.

Edited August 15, 2014 by Isegrim

[Dr_Arrow]

Is that really so? Or rather, does that really matter that much? I mean, if I fly always at 100%, the governors prevent me from going to 101% or more, then I reduce my service life of 5 hours per flight hour.

But if I would just fly at 99% all the time, all would be fine? Wouldn't it be rather that in this case I would reduce the service life by i.e. 4.75 hours per flight hour?

 

What I try to say is, the service life is an estimated value based on some "average" flying characteristics. With higher average strain on the engine, the wear rises exponential, allright, but as long as the engine is operated within it's defined limits (and the governors are ensuring that), everything is fine, no? There is no "technical order" that specifies that flying at 100% must be resticted to 10 minutes max or something like that.

 

 

It is different for every engine as defined by its manufacturer. For example the engine I am currently working on has the following service life schedule: Up to 80% of the current limit 1 second of real operation equals 1 second of service life. Above 80% of the current limit up to 90% it linearly increases from 1 to 5 and from 90-100% it again linearly increases from 5-8. So if you operate it at 99%, one second of operation costs 7.7 seconds of service life.

[Flagrum]

It is different for every engine as defined by its manufacturer. For example the engine I am currently working on has the following service life schedule: Up to 80% of the current limit 1 second of real operation equals 1 second of service life. Above 80% of the current limit up to 90% it linearly increases from 1 to 5 and from 90-100% it again linearly increases from 5-8. So if you operate it at 99%, one second of operation costs 7.7 seconds of service life.

Semi-OT question: how is the remaining service life of an engine "measured"? or estimated? I take from your explanation that pilots are "encouraged" to limit the use above 80% if possible. But how do you know what they really do? Is this logged somewhere somehow? Or is it just decided during inspections by assessing the general wear?

[Dr_Arrow]

Semi-OT question: how is the remaining service life of an engine "measured"? or estimated? I take from your explanation that pilots are "encouraged" to limit the use above 80% if possible. But how do you know what they really do? Is this logged somewhere somehow? Or is it just decided during inspections by assessing the general wear?

 

Yes, it is logged in the electronic engine control unit (EEC) or HMU (Health management unit) - it is dependent on the engine type, it is a part of FADEC - Full authority digital engine control system, which is presently used on most modern engines. You can read different engine logs from the unit (raw engine data), operational time, service life, number of starts, error codes, limits abuse, etc. The logged data are again proprietary for each engine type and architecture of the FADEC used.

[AlphaOneSix]

1. The engine operating time at take off power should not exceed 10% of the total operating time throughout the TBO, allowed time of continuous operation is 6 minutes. In case of necessity it is allowed to run the engine continuously for 15 minutes at takeoff power provided the summed operating time in these conditions does not exceed 1.25% of allowed operating time throughout the TBO (included in 10%). In case of failure (shut down) of one of the engines it is allowed to run the other engine at take off power for 30 minutes within 0.5% per TBO.

 

2. The engine contingency power is used only in case of failure of one of the engines. The engine operating time at contingency power should not exceed 0.1% of total operating time throughout the TBO. It is allowed to run the engine continuously at contingency power for 2.5 minutes without any limitations within the mentioned operating time.

 

TBO time varies, but is typically 1500 hours. So, for example, if you run at contingency power for 1.5 hours before the end of the 1500 hour overhaul cycle, the engines need to be overhauled at that time. You could run at takeoff power for a combined total of 150 hours within a 1500 hour TBO cycle, but only 6 minutes at a time with a 5 minute "rest" in between each 6-minute window. Once you go past 6 minutes, you enter into the 1.25% zone, where you can only have 18.75 hours per 1500 hour TBO cycle.

 

All of this is recorded manually by the flight engineer, whose responsibility includes tracking how long the engines are in each power regime.

 

Also, HMU on a turbine engine stands for hydromechanical unit, and does not typically exist on an aircraft with a FADEC. FADEC-equipped aircraft usually have an FMU (fuel metering unit) instead. But the naming conventions vary by manufacturer, it seems.

Edited August 16, 2014 by AlphaOneSix

[Dr_Arrow]

Thanks a lot Alpha for the great information, it would be interesting to have it implemented(but probably too complicated and only in campaign).

[Capt Zeen]

Thanks a lot Alpha, thats very interesting.

[BitMaster]

I havent managed yet to ruin a Kamov engine in flight just by misuse. From what they say ( the RL people who built it in a YT video) it is ALMOST impossible to ruin this engine in flight.

 

For the sake of realism I always try to avoid the limiters but sometimes you gotta get all there is to make it and it has proven to withstand it.

 

Good Kamov..I love you

 

Bit

[AlphaOneSix]

Kamov doesn't make engines. :P

[BitMaster]

Kamov doesn't make engines. :P

 

 

Sure, I know that. The reportage was about the Ka-50 series and they also talked about the engine and said it is almost impossible to destroy the engine while airborne ( "almost" ).

 

Just simplifying things, that's all.

[AlphaOneSix]

Fair enough. I'll add this, however. The reason it's nearly impossible to ruin the engines is not because the engines are made of magic, it's because they are limited by the governor (EEG) from getting too hot or spinning too fast. Turn off the governor and you can smoke those engines in no time. It's quite a different concept from Western aircraft.

[Fishbreath]

I'm gonna have to try that tonight. <.<

[Isegrim]

I havent managed yet to ruin a Kamov engine in flight just by misuse. From what they say ( the RL people who built it in a YT video) it is ALMOST impossible to ruin this engine in flight.

 

For the sake of realism I always try to avoid the limiters but sometimes you gotta get all there is to make it and it has proven to withstand it.

 

Good Kamov..I love you

 

Bit

 

I did managed this serveral times with EEG on and doing hard Maneuvers and Aerobatics with the KA-50.

You just need to do fast full collective/no collective drops and pulls.

After quite a while you will notice that one of the Engines is running hot and does less power than the other one.

But never killed them completly.

[BitMaster]

Yep, the Governour... the magic piece of hardware :lock:

 

I am going to fiddle with it, with & w/o GOV and see how I can ruin one of those Turbines ;)

 

 

If you look at the Su-25T and it's engines, there you have to go 100% when fully armed and fueled to even make it off the ground and into the air. They seem to be made to run at 100%

for a considerable time, at least in DCS, dunno how long you can go 100% in RL but it's gotta be at least 10-15 min to get altitude and speed when on a SEAD mission ( that's my favorite thing to do in the Su-25T ).

 

Small site note:

One of our Club members is the maker of the world smallest turbine, Kolibri, just around my corner. My friend Peter and the him did a test run on one of the development stages of a Kolibri ( after some considerable amount of german beer, that must be noted to understand this ! ).

Usually the ECU/GOV however you call it, limits this 200ml Coke can size beast to 250.000 rpm

with about 25N thrust. The stable working dev models do around 280k with 28N and they wanted to see

how much is possible...well..they put on some motorcycle helmets ( remember the beer ?) and

unlocked the ECU.. 300k rpm...temp OK, thrust 30N..lets move on...310k...still OK...320k...ahh we are getting close and Peter left the room cause he was scared by blades flying off and cutting his head off, well, Martin went on...330.000 rpm 33N thrust and just about at the point where the

hot and elongated blades were about to scratch the housing... temp was abnormal and Maertin shut it down before some serious incident could happen. the turbine was DONE but they knew that at least 300k rpm are manageable with the current materials and ECU, pump and exhaust.

AFAIK his most recent Kolibri is around 30N @ 300k rpm, weighting about 300 grams +/-

That's what happens when you give german engineers too much beer and some technical stuff to research..LoL

When run inside parameters, afaik 50h run time is what they do before inspection and change of bearings ( ceramic ) and some other stuff too.

It is amazing how you can squeeze that much technique into a 200ml coke can sized housing and have it run reliably.

That same guy built a unique rotor blade balancing machine for the Swiss SAR team, they were not pleased with the manufacturer balanced blades ( think it was Bo-105, but not sure ) and service intervals were too short and wear & tear too high. A real genius mind.

 

 

 

Bit

[AlphaOneSix]

Temperature of the turbine blades is the single biggest limiting factor in turbine engine power production. Hopefully, one day we'll have ceramic blades or something that can withstand much higher temperatures, and then you will see much higher power output for a given size.

[sobek]

Not so sure, the problem with higher exhaust temperatures is that they increase nitrogen oxide emissions. I don't know about regulations for aviation engines, but, not without some irony, what limits evolution of efficiency in piston engines most currently are the regulations on emissions.

[BitMaster]

Efficiency... with Newtons laws there are well defined limits as how much you can gain from what you pour in. Afaik the max you might get is 50%, the other 50% go into the engine and produce heat ( at least with standard cyl. orientation and movement, a Wankel might have some advantage here with rotating instead of oscillating masses ).

 

I actually prefer electric, OMG that TORQUE, from RPM-1 on it wants to break your neck and burn that Porsche next to you... if there wasn't the max mileage thing still.

 

 

I ultimately want a flying Saucer as my Motorhome...hehe With AGP, Anti Gravity Propulsion.

 

Guys, have some more beer and make me one...

[ShuRugal]

Um, Bit, what part of Newtons Laws of Motion have anything to do with efficiency of a heat engine?