Over torque and climbing

[gaspuch62]

This seems to happen every time I want to fly through mountains. I'll fly the black shark a good ways through, but at some point the machine just won't generate enough lift to get over the mountains (even short parts). Most recently, I had a loss of lift and I couldn't get the thing to stay aloft. I couldn't pull the collective without overtorquing the engines. Is the BlackShark not designed to fly at high altitudes?

[Paganus]

It can fly over all the mountains on the current map. It sounds like you are over speeding the engines to the point of one of them shutting down.

 

When flying just make sure those engine overspeed lights stay off.

[GGTharos]

Fly at 130Kph IAS. This is your best climbing speed. If you're at that speed and you see you won't get over the mountain, you started your climb too late. Turn around and try again.

 

This seems to happen every time I want to fly through mountains. I'll fly the black shark a good ways through, but at some point the machine just won't generate enough lift to get over the mountains (even short parts). Most recently, I had a loss of lift and I couldn't get the thing to stay aloft. I couldn't pull the collective without overtorquing the engines. Is the BlackShark not designed to fly at high altitudes?

[Raptor9]

Like GGTharos said. You can also spiral or zigzag your way up; just keep your bank angles shallow otherwise you'll offset the vertical lift too much. If you start getting the low rotor rpm warning, reduce the collective slightly to get the rotor rpms back within limits. RPM's have more of an impact on total lift than pulling more pitch.

 

Lightly loaded with fuel and no weapons or ammo, I've had the Shark at 24,000 feet, my personal best. Took forever though, lol.

[Odin_74]

Also you have to turn on the rotor deice system.

For some reason you lose performance when it's below zero C, even in clear air.

It's a DCS thing.

[sobek]

For some reason you lose performance when it's below zero C, even in clear air.

It's a DCS thing.

 

That's because of engine icing, and that is definately not just a DCS thing. Also, engine de-ice will cut a few hundred HP from your shaft HP because bleed air from the compressor is diverted to keep the intake free of ice.

[Odin_74]

I'm talking about rotor deicing.

 

If the dewpoint spread is low, you do risk icing on the engine intakes even in clear air, yes.

Intake deice uses power, indeed.

I haven't noticed any negative effects using the rotor deice, but I haven't done any serious testing.

[sobek]

If the dewpoint spread is low, you do risk icing on the engine intakes even in clear air, yes.

 

The effects of humidity on icing are not modelled at this point. However in general performance of all aircraft increases greatly as temperature decreases, as it should.

[flanker0ne]

Maybe that's a good occasion for learn to use the ABRIS.

By asking him to calculate the Initial Climb Point based on datas you are able to provide.

[Raptor9]

The effects of humidity on icing are not modelled at this point. However in general performance of all aircraft increases greatly as temperature decreases, as it should.

 

To a point, once you get further below the freezing point, turbine engines actually start to suffer performance. Each model of engine varies of where that point is, but it's more of an issue with helicopters since the engines directly power the lifting surfaces.

 

From my own play, it would seem that the Ka-50's rotor de-ice in DCS is indeed electrical, since I only get a power loss when using engine de-ice.

[Isegrim]

More Altitude=thinner Air=less rotor lift=less engine Performance

+Anti ice engine performance drop. Prevents Helicopters from flying into Space since 1936.

[BitMaster]

Learned that too on a mission with the Ka-50 that I modded for heavy snow and cold weather.

 

About half way to the traget I lost so much lift that I had to land and rethink my knowledge about the Kamov systems. It turned out that I had the rotor anti-icing turned on but mis-switched the engines' anti-icing. So I landed, switched on anti-icing for the engines,

waited like 5 minutes with turbines left at full throttle auto and then gently began to fly forward again. I noticed an impact on performance but I expected that, the energy needs to come from somewhere. I was never above 100m SL, fully fueled and armed to the teeth.

 

On the other hand, I had the Ka high in the skies, like 20.000+ feet at some points in other scenarios without engine anti-icing engaged. I might have had rotor anti-icing on but for sure none for the engines and I happily climbed way way higher than Mt. Elbrus. But that was done without weapons ( VA Server ) and fuel was 50% or less.

 

One more thing we gotta cope when we fly. I love this ! :)

 

 

Bit

[sobek]

To a point, once you get further below the freezing point, turbine engines actually start to suffer performance. Each model of engine varies of where that point is, but it's more of an issue with helicopters since the engines directly power the lifting surfaces.

 

Based on what phenomenon? As the density of air increases, so does the maximum power output of turbine engines, because it is massflow dependant. I'd be interested to know what effect would mitigate this because i've never heard of it.

[Isegrim]

High Temperatures are also not liked by Helicopters.

[ShuRugal]

Based on what phenomenon? As the density of air increases, so does the maximum power output of turbine engines, because it is massflow dependant. I'd be interested to know what effect would mitigate this because i've never heard of it.

 

maybe he's thinking about excessively dense air leading to a compressor-stall situation? That's hardly a loss of performance, though, and something any good governor would be able to cope with.

[Raptor9]

sobek, ShuRugal,

 

The effect I'm referring to is Ng limiting, but not sure if that's the universal term or not. Depending on individual engine design, there is a limit to the volume of air or fuel that can be pushed through an engine. So yes, it is mass-flow dependent, but in very cold temperatures where the air is dense, the engine either can not spin fast enough to pull additional air, or the fuel system cannot physically pump enough fuel into the combustor.

[ShuRugal]

sobek, ShuRugal,

 

The effect I'm referring to is Ng limiting, but not sure if that's the universal term or not. Depending on individual engine design, there is a limit to the volume of air or fuel that can be pushed through an engine. So yes, it is mass-flow dependent, but in very cold temperatures where the air is dense, the engine either can not spin fast enough to pull additional air, or the fuel system cannot physically pump enough fuel into the combustor.

 

ahh, engineering limits, then, not anything imposed by the nature of a combustion engine, then. That does make sense.

[AlphaOneSix]

For the Ka-50, this dropoff starts at around 2600 meters. That is, below 2600 meters above sea level, colder air results in more power all the way down to the engine's minimum ambient temperature of -60C. Above 2600 meters, the drop occurs at warmer temperatures. For example, at 4000 meters above sea level, engine power output starts to drop at -5C, and it stays at about -5C all the way up to 6000 meters above sea level. For a midpoint, at roughly 3300 meters above sea level, engine power starts to drop off at around -30C. Beyond the "dropoff" points I've mentioned above (that is, as the air gets colder), the power output of the engine drops.

[sobek]

Interesting, but what is the reason for the drop off? I would have assumed that as the air gets colder, it counters the effect of decreasing density at increasing height, somewhat negating the power loss.

Edited March 28, 2014 by sobek

[Raptor9]

AlphaOneSix, do you by chance have open-source performance planning charts for the Ka-50 or Mi-8 or both? I built a sort of open-map COIN theater with Sharks and Eights and those would definitely help in planning precise en-route and on-station times. Up to this point I've been doing the old-fashioned fuel consumption check of noting X amount at Y time and waiting 15 mins and re-check, lol. I would imagine the Mi-8 charts would be out there on the net somewhere, not so much with the Ka.

Edited March 28, 2014 by Raptor9

[AlphaOneSix]

I don't have anything for the Ka-50 specifically. I have more Mi-8 documents than I know what to do with, along with the TV3-117VM manuals. For planning purposes we use 900 liters per hour on the fuel burn, although it's usually more like 800. I'll see what I can dig up, I know I have performance planning charts for the Mi-8 somewhere.

[Fishbreath]

I built a sort of open-map COIN theater with Sharks and Eights

 

Are you going to release this delectable-sounding piece of mission goodness? :P

[diveplane]

This seems to happen every time I want to fly through mountains. I'll fly the black shark a good ways through, but at some point the machine just won't generate enough lift to get over the mountains (even short parts). Most recently, I had a loss of lift and I couldn't get the thing to stay aloft. I couldn't pull the collective without overtorquing the engines. Is the BlackShark not designed to fly at high altitudes?

 

reduced fuel load will help in climbing performance .

[Raptor9]

AlphaOneSix, thanks. I'll use those numbers and see what I come out with. I'm always interested in how much loiter time I can wring out of these Russian birds. Usually ammo runs out first though. :gun_rifle:

 

Are you going to release this delectable-sounding piece of mission goodness? :P

 

It is by no means that comprehensive It's mainly just a 160x200km piece of Russia with a bunch of randomly generated insurgent units activated at each mission start. If you want to know more, send me a PM, and I'll explain more if your interested. I don't want to derail the core topic of this thread.

[WildBillKelsoe]

If you're referring to the other side mission I used to have the same problem but soon realised that I'm going too fast for the climb. 170 kts is usually good but get to the top first then nose down once over the hump. And don't get the overspeed RPM lights on.