Wrong Russian fighters performance at high alts again

[6./ZG26_5tuka]

Quicktest Fw 190 at GL (250m AMSL):

 

- 530 km/h at 1.32 ata

- 555 km/h at 1.42 ata

 

Just going for GL data so far to see how the test results compare to each other and how accurately this testing method is. If it's worth it I may extend it to a real testing series.

[Matt]

You could create a MP mission with an airfield which has all planes avaliable, even using multiple different starting altitudes. Would be the most time efficient way.

 

Assuming that you can host a MP mission, not 100% sure if that's possible now, have not tried it myself. If that's not possible you would indeed have to create a mission for each plane and starting altitude each.

 

Since we're totally off-topic i guess, there's always been something iffy with the Bf 109 radiator. With 15 °C outside temperature, the radiators open very wide (almost to fully open) even with 1.3 ATA at ground altitude, so testing with automatic radiators makes no sense.

 

Now this was before the most recent update, maybe it got changed.

Edited February 26, 2015 by Matt

[6./ZG26_5tuka]

You could create a MP mission with an airfield which has all planes avaliable, even using multiple different starting altitudes. Would be the most time efficient way.

 

Assuming that you can host a MP mission, not 100% sure if that's possible now, have not tried it myself. If that's not possible you would indeed have to create a mission for each plane and starting altitude each.

 

Since we're totally off-topic i guess, there's always been something iffy with the Bf 109 radiator. With 15 °C outside temperature, the radiators open very wide (almost to fully open) even with 1.3 ATA at ground altitude, so testing with automatic radiators makes no sense.

 

Now this was before the most recent update, maybe it got changed.

If you referr to my test I indeed used automatic radiator contorll (expert mode). I can not comment on it's influrence but it seemed to be as oyu described, far more open radiators than in winter conditions. The water temperature didn't rise above 90° though, which is the optimal temperature for best engine performance.

[Brano]

Thats why you have to perform test according real conditions.As I did for Yak.It is essential to keep engine within its operational limits.Same with radiators.If you are pushing too much on engine,it needs more cooling which leads to radiators being more open.This is contraproductive as fully open ones can reduce your max speed by significant margin.

So if you want to test Me109F,better search at kurfursts site how it has been done and under which cicumstances etc.Pushing throttle fully-up till engine dies is not the way how those tests were performed.

[6./ZG26_5tuka]

I agree with you Brano though this was just a quick test to detrmine the basic difference between standard atmospheric and BoS winter condition. I had no intention performing accurate testing yet to compare it to real data, I'm just trying to gather first results and judge their credebility.

 

I'll probably redesing the mission completely as soon as I managed to edit the terrain to be flat and at SL so I dont have to bother about trees and mountains while testing.

[JtD]

Thanks guys for checking & posting figures.

[6./ZG26_5tuka]

Allright I think I slowly get the basics together. Here is a set of basic, generic test missions under ISA conditions (760 mmHG / 1013 Hp, 15°C) on the official Stalingrad Test Map (GL = 0 - 30m AMSL)

Other properties: Season = summer (don't know if it changes anything) , time = 12:00:00, no wind / turbulences at all altitudes, clear weather setting

 

Due to not being able to set airfields (yet) all missions include airspawn at ~1500m AMSL. Also I've only included fighter aircraft of BoS so far due to having the highest testing priority.

 

Hope this is helpful until I can figure out how to improve my editor skills.

 

Installation: Put the extracted "Performance Test Mission ISA" folder into your IL-2 Sturmovik Battle of Stalingrad\data\Missions folder and start the game. The missions are availabel in both Offline as well as Online mode.

Edited February 26, 2015 by Stab/JG26_5tuka

[303_Kwiatek]

Unfortunately mission dont work for me - during loading mission i got game freeze.

[SCG_Space_Ghost]

Unfortunately mission dont work for me - during loading mission i got game freeze.

 

Same. Uninstalled again until things get worked out. I need the room on my SSD.

[6./ZG26_5tuka]

Unfortunately mission dont work for me - during loading mission i got game freeze.

That's strange, I'm sure everythign worked fine for me I'll take another look at it and reupload it once I have cleared out that issue....

[6./ZG26_5tuka]

Tested the Bf 109 -4 and G-2 mission, no freezes for me. The loading times are a little long so I expected it to be freezed at some point, but it worked. Donnu what got wrong with the dowload.

 

New tests: Comparison F-4 / G-2

          1.32 ata, radiator auto        1.32 ata, closed radiator            1.45 ata, closed radiator

F-4             499  km/h                                551 km/h                                 565 km/h

 

G-2            498 km/h                                 535 km/h                                  -----------

 

Don't know with which radiator mode both 109s were tested in reality, but it seems we have to use manual raidator for most of the tests as Matt pointed out since auto will always fight you to keep the water temperature at point 80°C. The tolerance area reaches to roughtly 110 °C though so this is of course a major downer if you want to acchieve max performance (aside, despite flying wiht closed rads and time compression, my engines didn't overheat past 90°C n ISA conditions).

 

Still, taking the difference between the G-2 and F-4 into consideration, I feel Kwiatek is right in his assumption of the F-4 being overperforming.

[Saurer]

According to this they kept the water at 103°C

 

http://kurfurst.org/Performance_tests/109F4_Datenblatts/109F4_dblatt_calculated.html

[Brano]

According kurfurst max sea level speed of Fridrich was 523km/h at 1.3 Ata/2500rpm/1200PS.

Radiators were opened 50% during climb and during level flight in such condition that coolant temperature was 103C.I guess somwhere around 25% +/-

These are the values you have to follow when performing test.To be comaprable with original tests

[6./ZG26_5tuka]

I see but as I said even with time compression I struggled to even reach that high temperatures Guess something is wrong with the 109's radiators ingame than...

 

Talking about relative performance though the F-4 clearly is superiour to the G-2 which is wrong.

[Brano]

One more remark.You should take of from the airfield to preheat the engine properly.Spawning in the air gives you minimal engine temperatures.In mission builder there is condition for aircraft,smtg like "place on ground" This will enable a/c to take off from where you position it.Like lets say from parking stand.

[303_Kwiatek]

Tested the Bf 109 -4 and G-2 mission, no freezes for me. The loading times are a little long so I expected it to be freezed at some point, but it worked. Donnu what got wrong with the dowload.

 

New tests: Comparison F-4 / G-2

          1.32 ata, radiator auto        1.32 ata, closed radiator            1.45 ata, closed radiator

F-4             499  km/h                                551 km/h                                 565 km/h

 

G-2            498 km/h                                 535 km/h                                  -----------

 

Don't know with which radiator mode both 109s were tested in reality, but it seems we have to use manual raidator for most of the tests as Matt pointed out since auto will always fight you to keep the water temperature at point 80°C. The tolerance area reaches to roughtly 110 °C though so this is of course a major downer if you want to acchieve max performance (aside, despite flying wiht closed rads and time compression, my engines didn't overheat past 90°C n ISA conditions).

 

Still, taking the difference between the G-2 and F-4 into consideration, I feel Kwiatek is right in his assumption of the F-4 being overperforming.

 

Yes it looks that F-4 is overperforming here comparing to G-2.

 

German speed tests IRL were made mostly with 25% open radiator.

 

Speaking about Russian planes we know that they have IRL problem with overheating so probably in past they were need to keep more open radiators casue engine overheat.

 

Question is also if BOS simulate it adequatly becasue if in game Yak-1 could fly for long time with only 25 % open radiators it could achive more speed then it could do IRL with e.x 50 % open radiators.

Edited February 27, 2015 by 303_Kwiatek

[Sokol1]

Adjusted IAS to TAS using this : http://www.hochwarth...Calculator.html

 

There is no place to put IAS on that page.

 

 

Based on previous pages Kwitek calculations, and looks like the "dossie" collect by Celestiale use this page for calculations... 

 

I bet if used this one (think =FB=Visk use, or use НРК) the results will be slight different: 

 

http://www.avsim.su/f/utilities-21/navigation-slide-rule-nl-10-for-windows-29345.html?action=download&hl=

[6./ZG26_Emil]

Somebody mentioned earlier in the thread that since air combat rarely happens at maximum speed they thought it not to be a major issue. Surely if the engine is over performing at altitude then the LaGG and Yak will not only have too high a speeds but also improved climb rates as well, am I wrong about this? From what I've seen online the Yak-1 climb performance (at altitude) seems much better than I would expect compared to the G2 when (in the latter) a spiral climb should be a very effective tactic.

[Brano]

TAS at 3850m = 584km/h

 

TAS at 5000m = 544km/h

I just did the test as JtD suggested=measuring speed with help of stopwatch and grids on map (1 grid=10km).Tracked distance was 4 grids=40km

Same conditions as with my previous test,which was recalculated for ISA temp at given height (cant be precise as we do not know real temp at given alt in game)

 

Results>

TAS at 3850m=580km/h

TAS at 5000m=578km/h

+ additional

TAS at 6000m=569km/h

[CaK_Rumcajs]

I just did the test as JtD suggested=measuring speed with help of stopwatch and grids on map (1 grid=10km).Tracked distance was 4 grids=40km

Same conditions as with my previous test,which was recalculated for ISA temp at given height (cant be precise as we do not know real temp at given alt in game)

 

Results>

TAS at 3850m=580km/h

TAS at 5000m=578km/h

+ additional

TAS at 6000m=569km/h

Very nice to see TAS measured on the map. Probably the only reliable way to determine TAS precisely. (I just hope there was no wind)

 

Drop of only 11km/h in TAS 2150m higher than max speed height seems to be really suspicious. I don't see a way this to remain unchanged.

[Brano]

IMO what we have in game is Yak representing period in between s69 and s85 which is June-august 42 production.We can't take s69 as the only series fighting over Stalingrad in nov42-jan43.There were most probably even s99 yaks flying over there (early yak-1b with gargot)

And in no test report from NII VVS have I seen that they tested yaks over 5k.What for?

My conclusion is the same.There is no sensational overspeeding of yak as is suggested by OP.The only problem that I see is how vysotnyi korrektor is(not) working.

 

Howg

PS:there was no wind set

Edited March 3, 2015 by Brano

[JtD]

If you look at Yak-1 figures (or generally Yak's with PF engine) from the TsAGI book, you'll see speed drops of around 40km/h between full throttle altitude and 6000m. 11km/h is really wrong. I hope you're right and this is a consequence of the missing mixture correction. Have you had any feedback about this from the developers? I didn't follow the bug report topic in detail.

 

I'll also maintain until proven wrong that 15-69 tests with 510 / 574km/h were optimistic, because there was no radio installed on the aircraft during these tests. I've got it from two independent sources, but they only suggest and don't state for certain (anecdotal evidence). So even with variance in the series and possibly small improvements in series not modelled but represented in game, s69 figures should be the upper limit of performance. But, overall, it appears to be as accurate as the Fw190 as far as speed is concerned.

[Brano]

What I read in Stepanec book was,that surprisingly weight reduction didnt play significant role in achieving higher top speeds.Major improvements were done with tweaking of fuselage aerodynamics and general increase of manufacturing quality.All of these were done for PF equipped Yaks continuously from s69 up to s111,considered as first "trully" Yak 1b (lowered rear fuselage,retractable tail wheel,1xShvak+1xUBS...)

What I forgot to check during my test was MP decrease at altitudes above 4k.I guess it is not as significant as it should be.Because of vysotnyi korrektor.

As I mentioned before,I did not get answer from devs.I posted my "doubts" in "Question for developers" thread.Twice 

 

Happy testing 

[II./JG77_Manu*]

I just did the test as JtD suggested=measuring speed with help of stopwatch and grids on map (1 grid=10km).Tracked distance was 4 grids=40km

Same conditions as with my previous test,which was recalculated for ISA temp at given height (cant be precise as we do not know real temp at given alt in game)

 

Results>

TAS at 3850m=580km/h

TAS at 5000m=578km/h

+ additional

TAS at 6000m=569km/h

Ok did you test any other bird? Luckily i got some time on the weekend, will test every fighter at 0, 3650, and 6k, then we can compare our results. Will make Fraps vid, just in case

[Brano]

No,only Yak.Don't have much time for that.And finally I am not a chart monkey or test pilot.I'm casual hobby simmer.Will leave further testing for those who think that it's what this game is all about.

[II./JG77_Manu*]

Will leave further testing for those who think that it's what this game is all about.

You mean those who care about historical accuracy rather then game balacing

[Dakpilot]

Oh dear there you go again losing all credibility you have gained....

 

Cheers Dakpilot

[JtD]

I just found that this topic is misnamed - it should be called "wrong high altitude performance for several fighters".

 

I went and took the Fw190 for a spin at 9000m, usual procedure, and achieved a top speed of 608km/h@9000m. According to Fw, the top speed at that altitude should be about 570 km/h. So while about matching historical performance at full throttle altitude, the aircraft is about 35 km/h too fast 3000m above that altitude. It's not a Yak specific problem, in fact I'd now expect it to be a general problem for all aircraft.

Edited March 6, 2015 by JtD

[303_Kwiatek]

At which power settings? RL A-3 got  580 kph at climb and combat settings and 620 kph at emergency settings at 9 km.

[II./JG77_Manu*]

Oh dear there you go again losing all credibility you have gained....

 

Cheers Dakpilot

Thanks for your overly important contribution to this thread. As ever. Cheers Celestiale

[JtD]

At which power settings? RL A-3 got  580 kph at climb and combat settings and 620 kph at emergency settings at 9 km.

Obviously I've been testing at combat/climb, as always. 580km/h RL not corrected for compressibility, right?

 

Speaking of which - does anyone know if the Soviet figures of the time were generally corrected for compressibility? Does anyone know standard correction methods they applied?

[L3Pl4K]

Looks like the Yak1 is still to fast on high alt, when will this bug been fixed?

[Dakpilot]

Looks like the Yak1 is still to fast on high alt, when will this bug been fixed?

 

Probably when the Bf 109 F4 and Lagg 3 high alt performance is addressed as well 

 

Cheers Dakpilot

[L3Pl4K]

 

 

Probably when the Bf 109 F4 and Lagg 3 high alt performance is addressed as well

Ok then Yak1 Lagg 3 and F4. In the G2, you feel ripped ago at high alts

[II./JG77_Manu*]

Probably when the Bf 109 F4 and Lagg 3 high alt performance is addressed as well 

 

Cheers Dakpilot

 

F4 overspeeding by what like 10-20kph? Yak overspeeding around 70..you can hardly compare that

[303_Kwiatek]

Probably when the Bf 109 F4 and Lagg 3 high alt performance is addressed as well 

 

Cheers Dakpilot

 

So probably never

Edited January 8, 2016 by 303_Kwiatek

[Nocke]

For level flight, aircraft mass should not change max speed !

Really? I am no expert in this, but I would guess that a heavier plane needs a higher angle of attack, thus increasing drag.

Any expert here to confirm or not this?

 

Just for curiosity

[JtD]

It has an effect on top level speed, but it is near negligible. Increased weight causes increased lift induced drag, which - compared to the parasitic drag at top speed - is very small. In about the region of 5-10% of the total drag would typically be lift induced. So at the speeds typical for these aircraft, as a ballpark, a 10% weight change would cause a 1% speed change.

Edited January 10, 2016 by JtD

[Nocke]

It has an effect on top level speed, but it is near negligible. Increased weight causes increased lift induced drag, which - compared to the parasitic drag at top speed - is very small. In about the region of 5-10% of the total drag would typically be lift induced. So at the speeds typical for these aircraft, as a ballpark, a 10% weight change would cause a 1% speed change.

Wow.

 

Perfect answer.

 

Thx a lot!