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Skoshi_Tiger

World Altitude Record Lagg

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Just for a bit of fun I tried to see how high I could get the LaGG3. As I haven't seen any other similar posts, here is my claim for the world record.

Details

Date/Time:2013-11-20/3:36PM WAST

Height:8200 Metres

Engine settings

RPM:2700

Full throttle

Supercharger:second gear

Indicated speed:~200kph

Notes: mushy controls. Hard to keep level

 

post-80-0-96328900-1384934273_thumb.jpgpost-80-0-90704900-1384934281_thumb.jpg

 

OK Guys! This record is meant to be broken!

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I got it up to 9000 m without too much trouble:
2013_11_19__3_26_24_zps99cb6092.png

This was using 'Normal' rather than 'Expert' settings.

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I got it up to 9000 m without too much trouble:

2013_11_19__3_26_24_zps99cb6092.png

 

This was using 'Normal' rather than 'Expert' settings.

Mine was in expert mode so I'd be taking that as the baseline for a world record. It's interesting that you had dropped your mixture to 25% I'd forgotten about adjusting that. Also I would have been loaded up with about 33% fuel on take off.

Edited by Skoshi_Tiger

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10,100m for me, highest I could hold. Note that the cheat instruments show AGL, not ASL.

 

post-13947-0-99414500-1384936398_thumb.jpg

Edited by =LD=King_Hrothgar

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@Skoshi_Tiger - In 'normal' mode, the mixture control is automatic.

 

@=38=Tatarenko - It's worth bearing in mind that service ceiling figures are probably based on standard atmospheric conditions. We don't know for sure what the map conditions are, though they are presumably colder, which might improve performance slightly.

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Ceiling should be 9700m I think.

 

Yup, with effort I hit something over 9600m on the cockpit altimeter yesterday. I wanted to get to 10km but couldn't quite make it.

 

Engine controls set to what you would expect, full throttle and rpm, lean mix, supercharger 2nd gear. I remember using flaps in the last few hundred meters.

Edited by pixelshader

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hey up there have you checked if the bos world is rounded?

 

you can know by levelling the plane and seeing if the gunsight aims at the horizon or above :)

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hey up there have you checked if the bos world is rounded?

 

you can know by levelling the plane and seeing if the gunsight aims at the horizon or above :)

 

can't see much horizon.. only whiteness

 

it seems the ceiling of this plane is actually 10.2km

 

q5yHLwA.jpg

wi3CBTu.jpg

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One beef I've always had with sims (apart from MSFS-X) is that at a certain point the ground just stops. Okay, sure it cuts down on performance costs, but all the same, part of the majesty of flight is seeing the ground just going further and further away...

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I could not get higher than 8990 meters. Expert mode, full throttle, lean mixture, full rpm, second gear and fully closed cooling flaps for minimum air resistance...  :mellow:

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So I put her up to 9800m. Full lean mixture, both radiators shut and 2nd gear of the supercharger. In the end at 170-180 k/ph. Full real mode. Its more about patience I guess, it took kind of long time to get there. And its hard to keep it leveled because there´s no artificial horizon and the outside horizon...well its a total whiteout.

Also there is obviously no contrail modeled right now. Would expect it at 7000m or even lower due to the cold conditions.

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I might be wrong, but wouldn't it make more sense to set the prop governor to lower RPM at high altitude to force a coarser pitch that grips the thinner air better?

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I might be wrong, but wouldn't it make more sense to set the prop governor to lower RPM at high altitude to force a coarser pitch that grips the thinner air better?

On a 3 meter prop, at 10 km altitude, on a plane going 230 km/h IAS, the propeller tips are Mach at ~1800 RPM (someone might want to check my math). Propellers are not very efficient once they go supersonic. Running the engine at 1800 RPM will lose you LOTS of power versus running it at 2700 RPM, though, so you probably don't want to do that.

 

I don't know what the best RPM would be. I'd lean towards max RPM since the prop is going to be supersonic at any reasonable power setting anyway.

 

Minus the effects of Mach number, you'd definitely want max RPM. The prop advance ratio is already very high due to your high TAS at altitude, making it even higher by reducing RPM is only going to make your efficiency worse.

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On a 3 meter prop, at 10 km altitude, on a plane going 230 km/h IAS, the propeller tips are Mach at ~1800 RPM (someone might want to check my math). Propellers are not very efficient once they go supersonic. Running the engine at 1800 RPM will lose you LOTS of power versus running it at 2700 RPM, though, so you probably don't want to do that.

 

I don't know what the best RPM would be. I'd lean towards max RPM since the prop is going to be supersonic at any reasonable power setting anyway.

 

Minus the effects of Mach number, you'd definitely want max RPM. The prop advance ratio is already very high due to your high TAS at altitude, making it even higher by reducing RPM is only going to make your efficiency worse.

 

that can't be right

 

i think your mistake is taking engine rpm as equal to prop rpm

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Today I managed 9,600m on expert, but couldn't quite drag it the last 100m (or the 700m that would be required to beat the current record). Interestingly enough, it had nothing to do with airspeed, I was still doing around 210 km/h IAS, but I simply couldn't keep the plane steady enough at that altitude and had to deploy a little flaps to manage just level flight. Once trim is implemented, I'm sure I'll be able to get to 10km.

 

This might be faulty engine management on my part, but I noticed that the oil temperature seemed to reach it lowest point around 8,000m, where I could close the radiator completely without the oil temp rising, but when I climbed above 9,000, the temperature started rising again and quickly hit 100 degrees. At the highest point I had to keep my oil radiator open around 20% to keep it at 80.

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And the variation of results people get shows, that it's not just a matter of cutting the LaGGs performance at a preset altitude, but a dynamic model, that allows a good pilot to press the machine just beyond its nominal limits without necesarilly flying out into space.

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that can't be right

 

i think your mistake is taking engine rpm as equal to prop rpm

Oops, yeah. I don't know what the gearing is.

 

Double that 1800, then. You want full RPM.

Edited by NonWonderDog

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Here is the highest I ever went, so far:

 

2013_11_20__6_5_29_zpsa0e67ceb.png

 

:salute: MJ

Edited by =69.GIAP=MIKHA

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