How real is real?

[159th_Falcon]

Ok just curious here and i hope someone can tell me what is simulated and what not.

Last night i flew convoy hunt together whit Panzertard, after a good while of having great fun one of my engines got shot up thus losing quite alot of power.

now i dumped all my weapons to lose wait and made way for the return trip.

I had a mountain to climb thus i was thinking reducing the load on the engine even further, though im not sure to what lvl this is simulated.

:smartass:So here come the questions if the following is simulated;

 

Shutting down electrical systems (laser/Hud/Abris/lights) causes the generator to generate less power thus the engine has more power available for driving the rotors.

 

Flares have weight, dropping all your flares makes you lighter thus you need less power to fly.

 

Cannon rounds have weight, expending all your (gun) ammo makes you lighter thus you need less power to fly.

 

Is there an difference in power requirement from the engines when performing turns? for example an left hand turn needs more power then a right hand one???:smartass:

 

I guess thats it for now, curious if this is modelled in the shark and to what extend.

 

Also, im quite sure there is something like emergency power modeled and i believe you can activate it by pressing Page Up key. Though whenever doing this i have never seen an engine getting above 97% rpm

(is there an torque indicator in the shark?)

 

Looking forward to the replies and an possible oncoming discussion, please keep everything on topic though.

[Yskonyn]

Interesting concepts.

Please note that the following comments are just my opinion and might very well be incorrect:

 

-I think shutting down electrical systems do lower the load on the generators, however I do not think you will notice any difference in engine power because of this.

Usually bleed-air load or pneumatic taps are a big hit on engine performance, but I don't think electrics will impact too much.

 

-I have no idea how much Flares weigh, but I think their weight is insignificant as to whether you could create more performance by launching all flares.

 

-Cannon rounds might be different though. They are heavier without a doubt (at least as seen as the total amount you carry).

 

-The Shark has counter rotating blades which should nullify the tendency to torque to one side or the other, so no I don't think you need extra power for either turn.

[Waldo_II]

Shutting down electrical systems (laser/Hud/Abris/lights) causes the generator to generate less power thus the engine has more power available for driving the rotors.

I'm not sure if this is modeled, but if it is, the effect would be so small that there would be no notable difference in power to the rotors. I mean, if you were driving your car, would you go faster if you turned off your headlights and radio?

 

Flares have weight, dropping all your flares makes you lighter thus you need less power to fly.

I actually do not believe this is modeled. If you go to the options menu in the editor for a Ka-50 spawn (where you can change the amount of flares/chaff, gun load, weapon load, fuel load, skin, etc), the overall weight value does not change when you modify the amount of flares loaded. The difference woudn't be significant if they were modeled anyways, like the above example.

Cannon rounds have weight, expending all your (gun) ammo makes you lighter thus you need less power to fly.

This one is modeled. Just like for flares, if you go to the Ka-50 spawn options and you modify the gun load, you will see that the overall weight changes when you modify the load.

Is there an difference in power requirement from the engines when performing turns? for example an left hand turn needs more power then a right hand one???:smartass:

There is never a need for the engines to change the amount of power for a turn. At first thought you may think that for a rudder turn you may need to change engine power, but due to the coaxial rotor system, the engines should be giving the same power output as going forward (extracts power from the bottom rotor and adds to the top and vise versa. Same power all the time).

 

Also, im quite sure there is something like emergency power modeled and i believe you can activate it by pressing Page Up key. Though whenever doing this i have never seen an engine getting above 97% rpm

Yes, the top level on the throttle is emergency power. This gives the engines 100% of the power available all the time. This won't necessarily mean engines will reach 100% RPM, however. 100% RPM probably occurs in nonstandard circumstances, like when the air temperature is very high, the humidity is low, collective is at 0 degrees, and you are 3,000 meters in the air with no wind or clouds, and the engine governors are off. A constant 100% RPM could damage the engines, so I wouldn't doubt that the engine governors limit power to keep it below said percentage.

Answers in red.

[sobek]

Also, im quite sure there is something like emergency power modeled and i believe you can activate it by pressing Page Up key. Though whenever doing this i have never seen an engine getting above 97% rpm

(is there an torque indicator in the shark?)

 

This was partially answered in the post above, i'll just add some explanation to make it clearer.

 

The engine governors not only monitor RPM, but also EGT. The relation between RPM and EGT is dependant on atmospheric conditions (pressure, temperature, asf.). Therefore, not at all atmospheric conditions will you be able to reach 100% RPM because the EGT would reach catastrophic values first, so the governor kicks in and limits fuel flow.

 

If you increase the governor setting to emergency power, that only means that the limits, at which the governor kicks in fully, are higher.

[Panzertard]

You did a good job bringing that bird back over the mountains in those conditions, Falcon. Good fun to watch :)

 

EtherealN managed to mangle himself into a similar situation yesterday.

He wasnt able to quite stay airborne when he lost some percentage of one of his engines plus the hydralics - but manaqged to put it down onto the grass while focusing on the task ahead.

PS: He was flying under the influence from some cheap swedish beer.

 

Shutting down the generator for the stricken engine, emergency power and tossing out the remaining beer seems to have given him the power he needed and get the bird back home again.

[sobek]

Shutting down the generator for the stricken engine,

 

That will not make a difference, because the generators are driven by the main rotor gearbox anyway.

 

PS: He was flying under the influence from some cheap swedish beer.

 

I always thought there was no such thing as cheap alcohol in sweden :D

Edited November 23, 2009 by sobek

[Panzertard]

That will not make a difference, because the generators are driven by the main rotor gearbox anyway, IIRC.

Interesting - from Ethereals point of view he seem to be able to get some more percentage out of the engine when he did that.

Hm, I could have gotten it wrong though. Maybe he shut down the generator for the healthy engine to be able to reach emergency power.

 

I'm sure we'll get a explaination what he did when he returns from hibernation.

 

Doesnt having generators online draw power the total being available to drive the rotors?

Power that otherwise would have been present to turn the gears will instead be diverted into turning the generators?

The energy cant be "free" - it's quite impossible.

I think you see where I'm going :)

Edited November 23, 2009 by Panzertard

[Yskonyn]

That will not make a difference, because the generators are driven by the main rotor gearbox anyway.

 

Just out of curiosity;

Why are they then referred to as tied to the engines? If the generators are driven by the rotor gearbox what relation do they have to any engine?

[sobek]

Doesnt having generators online draw power the total being available to drive the rotors?

Power that otherwise would have been present to turn the gears will instead be diverted into turning the generators?

The energy cant be "free" - it's quite impossible.

I think you see where I'm going :)

 

I think the generators are not being physically disconnected from the rotor gearbox, just electrically. This means that if one generator ceases to work, the other generator has to provide twice the electrical power (or the voltage would cave in), therefore needing twice the torque to be turned. Additionally to having more losses in the one generator (Note: i don't know if more loss in total, see, i suck at electrodynamics :D) that is still working, you still have to turn the generator that is idling (although with much less torque). Nothing to be gained here, unless you turn both gens off and run with batt power (it runs infinitely, iirc) sacrificing realism.

Edited November 23, 2009 by sobek

[sobek]

Just out of curiosity;

Why are they then referred to as tied to the engines? If the generators are driven by the rotor gearbox what relation do they have to any engine?

 

I do not recall reading that the generators are tied to the engines (although they are, via the main rotor gearbox;)). They have no relation whatsoever. Turn one engine off and observe how both generators still stay online. Do some autorotation and observe how generators are driven off the main rotor gearbox.

 

This [1] schematic might help you understand how power is distributed.

 

[1] http://www.digitalcombatsimulator.com/index.php?lang=en&end_pos=1630

Edited November 23, 2009 by sobek

[Panzertard]

I think the generators are not being physically disconnected from the rotor gearbox, just electrically. This means that if one generator ceases to work, the other generator has to provide twice the electrical power (or the voltage would cave in), therefore needing twice the torque to be turned. Additionally to having more losses in the one generator (Note: i don't know if more loss in total, see, i suck at electrodynamics :D) that is still working, you still have to turn the generator that is idling (although with much less torque). Nothing to be gained here, unless you turn both gens off and run with batt power (it runs infinitely, iirc) sacrificing realism.

 

Of course - as you say, using 2 vs 1 generator may have that effect.

However I wonder if the cost running 1 or 2 generators versus none is neglegtable.

You could theoretically run on the batteries for a little while I suppose?

So how much power will a generator (or two) steal from the total power being provided by the tubrines (or rather derived from the gearbox)? :)

1%? 10%?

[Yskonyn]

Thanks for the input, appreciated.

Though I do question your theory about only one generator online needs to put out twice the power.

 

Its only logical to assume that the system has a split generator/electrical philosophy in normal operation, but in terms of redundancy I would expect one generator to be sufficient for all electric needs in case one generator fails. The power is just transferred by a tie-bus. (note that I did not yet look at your diagram) That's how most aircraft work.

 

Besides if the remaining generator would put out twice the power, all systems would melt down because of the amps increase. And how would it provide twice as much power? The gearbox is driven by the engine and normally the gearbox runs at a constant speed. If the remaining generator would have to double its poweroutput the gearbox would have to double its paces as well.

Edited November 23, 2009 by Yskonyn

[Frederf]

Probably 1% or much less. 2400HP engines are 1.8MW (millions of Watts). All the lightbulbs and computers and pumps in an aircraft might take a few thousand Watts at most?

 

Batteries provide DC power. No amount of batteries can provide AC power.

 

Power is voltage times current. If one generator would fail then the other would simply draw more current (amps, common unit). The voltages wouldn't change.

[Panzertard]

:thumbup: You're right - but there's also the efficiency of the generators to consider. A very inefficient generator may take quite a bit of power to run so it can maintain the level of consumption by the systems.

 

Ah, well - I'm not going to go that road because it's beyond the scope of the post ;)

 

I suppose I'll trick Ethereal into another ambush while he's sober and test it over again. ;)

[Yskonyn]

Batteries not providing AC power is not a matter op quantity, it's the current-type. Batteries provide direct current (one way) and AC systems need alternating current (back and forth).

I am sure you meant it that way, Frederf, but just to be clear enough. :)

Edited November 23, 2009 by Yskonyn

[Yskonyn]

:thumbup: You're right - but there's also the efficiency of the generators to consider. A very inefficient generator may take quite a bit of power to run so it can maintain the level of consumption by the systems.

;)

 

Isn't that a moot point, with all respect?

There's only one type of generator in the sim and that's the one provided for the KA-50. There's no issue about inefficiency because Gen 1 and 2 are modelled the same and are coded into the sim.

Wear, maintenance and model differences are irrelevant because they're not in-game. :D

[Panzertard]

Isn't that a moot point, with all respect?

There's only one type of generator in the sim and that's the one provided for the KA-50. There's no issue about inefficiency because Gen 1 and 2 are modelled the same and are coded into the sim.

Wear, maintenance and model differences are irrelevant because they're not in-game. :D

If you consider it that way - yes.

It wasnt what I meant really - but still - we're way past the OP right now so I'll stop here :)

[Yskonyn]

The title of this thread is quite big in scope, you know! ;)

[Panzertard]

The title of this thread is quite big in scope, you know! ;)

My intention was to indicate that if (theoritcally) the generators in the Ka-50 was extremly inefficient (the only one's in the game, indeed), let's say 1% then they would have to draw (consume) 100 times the power to provide 100% needed by the systems.

 

Assuming the systems need 1kW:

Of 2400HP/1790kW thats about 100kW.

If the systems require 5kW (at 100%), then you technically would loose 500kW.

Am I correct?

[sobek]

Thanks for the input, appreciated.

Though I do question your theory about only one generator online needs to put out twice the power.

 

Its only logical to assume that the system has a split generator/electrical philosophy in normal operation, but in terms of redundancy I would expect one generator to be sufficient for all electric needs in case one generator fails. The power is just transferred by a tie-bus. (note that I did not yet look at your diagram) That's how most aircraft work.

 

You got me totally wrong. If both generators put out P amount of power, one generator naturally puts out about P/2. One generator fails, the other generator has to put out P amount of power, thus twice the amount than before.

 

 

And how would it provide twice as much power? The gearbox is driven by the engine and normally the gearbox runs at a constant speed. If the remaining generator would have to double its poweroutput the gearbox would have to double its paces as well.

 

No, this is wrong. AC (and DC) Generator Power is not solely dependant on RPM. Explaining this would go beyond the scope of this post. Just research synchronous and asynchronous generator designs on the net.

 

Basically, the RPM can stay the same, but the torque needed to turn the generator at the same RPM increases, this way, the generator draws more mechanical power and puts out more electrical power.

 

The baseline is, if the sim electrical systems are modelled correctly, shifting power needs from both generators to just one should not increase the power available to drive the rotor.

Edited November 23, 2009 by sobek

[sobek]

 

Batteries provide DC power. No amount of batteries can provide AC power.

 

 

With an inverter, they can.

[Yskonyn]

You got me totally wrong. If both generators put out P amount of power, one generator naturally puts out about P/2. One generator fails, the other generator has to put out P amount of power, thus twice the amount than before.

 

Still this does not have to be? That depends on if they are both supplying the same systems. That's what I meant with seperate electrical circuits for each generator which, in empergency, can be joined by tie-busses.

Granted, I dunno how this works in the KA-50, you seem to know much more about it. It's not a statement of mine, more a question.

 

No, this is wrong. AC (and DC) Generator Power is not solely dependant on RPM. Explaining this would go beyond the scope of this post. Just research synchronous and asynchronous generator designs on the net.

 

Basically, the RPM can stay the same, but the torque needed to turn the generator at the same RPM increases, this way, the generator draws more mechanical power and puts out more electrical power.

 

The baseline is, if the sim electrical systems are modelled correctly, shifting power needs from both generators to just one should not increase the power available to drive the rotor.

 

Thanks for clarifying. I will look that up. :thumbup:

[Griffin]

"The left generator is switched to the CDU-1 (Central Distribution Unit) and the right to the CDU-2, which supplies the buses that feed the consumers. In case one generator fails, its buses are automatically switched to the buses of the serviceable generator."

 

It seems that the working generator has to do double work in this case.

[sobek]

"The left generator is switched to the CDU-1 (Central Distribution Unit) and the right to the CDU-2, which supplies the buses that feed the consumers. In case one generator fails, its buses are automatically switched to the buses of the serviceable generator."

 

It seems that the working generator has to do double work in this case.

 

Correct. To support this statement, please look at this [1] diagram of the onboard buses.

 

[1] http://www.digitalcombatsimulator.com/img/technology/HelModelDesc_Electrics_En.html

[EtherealN]

Interesting - from Ethereals point of view he seem to be able to get some more percentage out of the engine when he did that.

Hm, I could have gotten it wrong though. Maybe he shut down the generator for the healthy engine to be able to reach emergency power.

 

I shut down both generators. I also shut down all unecessary electronic equipment (even though battery draw isn't modeled from what I remember, since exact information of the draw of each component wasn't available to ED).

 

Basically, the stricken engine was notched down to idle, meaning it was still supplying power but not much. I compensated through setting the healthy engine to emergency power. This was where I first hit the wrong key combination, causing the stricken engine to shut down completely instead of going to idle, wherefore I was forced to land since my altitude just wasn't enough to make another go at it.

 

With that damaged engine not able to supply full power (it died when I tried on the ground), and even on idle it died as soon as I activated generators (not too much of a surprise really. :P ). I didn't attempt changing between the generators, which might have been good to test I guess.

 

You could theoretically run on the batteries for a little while I suppose?

 

IRL, yes, for a while. Though you will not have all systems running.

 

In the simulator, yes, forever. Though you will not have all systems running. At least if memory of past threads serve. This is caused by ED not knowing the actual power draw of all components causing some limitations on modelling of battery power.

 

Something that I know with relative surety to be modelled is the fact that engine dust protection does steal power from the engines, wherefore you shouldn't leave it on at altitude just because you'll get down to the deck eventually anyhow. I suspect that other such influences would also play a part.

 

I suppose I'll trick Ethereal into another ambush while he's sober and test it over again.

 

Good luck. :P

Edited November 23, 2009 by EtherealN