Climb test Yak-1 vs F-4 vs Fw 190

[JtD]

They are saying that if you close the radiators, your climb rate will improve. Some aircraft can do this in cold conditions without overheating, and get the benefit. Some aircraft like the Fw190 can't close the radiator, and therefore get no improvement from reduced drag.

 

So some aircraft have improved cold air climb performance because of a) more engine power and b) closed radiators, some aircraft just because of a) more engine power. That's true and applicable to the Fw190 situation, but I can't say if it really explains any differences there might be between the Fw190 and say the Bf109 in game in this situation.

Edited January 17, 2016 by JtD

[Dr_Molenbeek]

They are saying that if you close the radiators, your climb rate will improve. Some aircraft can do this in cold conditions without overheating, and get the benefit. Some aircraft like the Fw190 can't close the radiator, and therefore get no improvement from reduced drag.

 

So some aircraft have improved cold air climb performance because of a) more engine power and b) closed radiators, some aircraft just because of a) more engine power. That's true and applicable to the Fw190 situation, but I can't say if it really explains any differences there might be between the Fw190 and say the Bf109 in game in this situation.

 

To give an example, let's take the Fw 190A-5, which had radiator flaps.

 

Does the gain in climb, provided by the closure of radiators, will be the same at all altitudes ?

Edited January 17, 2016 by Ze_Hairy

[JtD]

No, it will as a trend gain more at higher altitudes, because drag as a trend costs more power up high than down low, so the same drag increase will cost more power up high than down low. But, as can be guessed by the "as a trend" phrase, this will not have an impact of several m/s, but a fraction thereof.

[Dr_Molenbeek]

No, it will as a trend gain more at higher altitudes, because drag as a trend costs more power up high than down low, so the same drag increase will cost more power up high than down low. But, as can be guessed by the "as a trend" phrase, this will not have an impact of several m/s, but a fraction thereof.

 

Ok.

 

Have you any idea/assumption of why does the A-3 in BoS loses so much when passing from 1st to 2nd supercharger speed, in winter ?

Edited January 17, 2016 by Ze_Hairy

[303_Kwiatek]

Cold denser air shoould give incrase in speed and climb not only radiator settings.

Edited January 17, 2016 by 303_Kwiatek

[Dr_Molenbeek]

Cold denser air shoould give incrase in speed and climb not only radiator settings.

 

Of course.

 

Take a look at the chart:

 

 

We see that in BoS winter, the 190 benefits from the +~4m/s (like the others BoS fighters) cold boost, but only at the first supercharger speed level. Once you reach ~1200m, something xxxx happens and when the supercharger switch on 2nd speed, the benefit of cold boost becomes almost insignificant (about 1m/s) compared to ISA climb rate.

 

Don't be surprised if an I-16 or a LaGG-3 can helicopter you at mid to high altitude. It's not the Russian fighter that overperforms in this domain, but your 190 that becomes a pork.

Edited January 18, 2016 by Ze_Hairy

[JtD]

Ok.

 

Have you any idea/assumption of why does the A-3 in BoS loses so much when passing from 1st to 2nd supercharger speed, in winter ?

To be honest, first thing I'd do before starting to speculate about an error in the FM or searching for a source to support the what I consider odd behaviour, is to reproduce your findings. Which I guess I won't do very soon, so I guess the rest has to wait as well.

[Dakpilot]

'Helicopter' and 'pork' are such good 'emotive' terms relating to....WWII  aircraft 'performance

 

always helps to bring that up

 

Cheers Dakpilot

[Dr_Molenbeek]

To be honest, first thing I'd do before starting to speculate about an error in the FM or searching for a source to support the what I consider odd behaviour, is to reproduce your findings. Which I guess I won't do very soon, so I guess the rest has to wait as well.

 

Well, keep us informed.

 

'Helicopter' and 'pork' are such good 'emotive' terms relating to....WWII  aircraft 'performance

 

always helps to bring that up

 

Cheers Dakpilot

 

Always as helpful on FM discussions.

 

Changes nothing, champion. 

[Crump]

Hi Crump, it's very nice to see you here

 

 

 

Now I don't understand you. As you mentioned above/before, Fw 190 Aa-3 should have settings 1,32 @ 2700 @ 0 m? I know almost nothing about Aa-3 (except well known basics), but in this list it seems, that there should be normal BMW 801 D with 1,42 @ 2700 @ 0 m (and 1440 PS on second gear). Am I lost something?

 

Thank you very much for any explanation.

The power is at 5700 meters....not 0 meters.

 

I will post the information.

 

Now please convert the Soviet power settings used on their captured example.

 

The Soviet units are millimeters of mercury. Simply convert to inches and then used the chart Improvided to go from inches of mercury to German "ata".

[Dr_Molenbeek]

 

Really close to the one made by JtD, months ago: 

 

Edited January 18, 2016 by Ze_Hairy

[Crump]

Cold denser air shoould give incrase in speed and climb not only radiator settings.

True Airspeed is reduced but IAS is "improved". A pilot is happy looking at his airspeed indicator in the winter but sad when he looks at his ground speed. Now that is in a typical winter day were pressure is high and temperature is low. In BoS, you have a less typical winter environment of low pressure and low temperature. Since winter started I can count on one hand the number if days pressure has equaled or been below standard.

[SR-F_Winger]

 

Really close to the one made by JtD, months ago: 

 

i bow before your persistence. Ist like fighting stubborn arrogant windmills. Practically no point. But you keep doing it.

[MK_RED13]

i bow before your persistence. Ist like fighting stubborn arrogant windmills. Practically no point. But you keep doing it.

... He has my admiration!!! 

[Dr_Molenbeek]

BTW if anyone want to send a PM to Han, about the 190 climb rate issue (especially winter), using the charts posted here, go now, because i feel like they are "hot" at the moment since they have reworked the behavior of Bf 109s at high speed (coming for next patch i guess), and it will not last long: http://forum.il2sturmovik.ru/topic/2396-pochemu-samolyoty-ne-razvalivayutsya-na-skorosti/?p=373477

[Guest deleted@50488]

Are you sure it is not because of your weight Hairy when you perform the tests ?  

[Dr_Molenbeek]

Are you sure it is not because of your weight Hairy when you perform the tests ?  

 

I specified the weight on the charts.

 

The thing is... even at 3850kg (no outboard cannons), the plane, ingame, climbs worse than it should do at ~3970kg IRL, according to datas. The bonus gained by removing the outboard cannons is of about ~0,5m/s.

 

And... we are still waiting for an answer to this question: http://forum.il2sturmovik.com/topic/7-questions-developers/?p=319816

[Guest deleted@50488]

I look fwd for it to Hairy... was just a joke that post of mine :-)

 

And I still do not like the induced snap-roll followed by inverted, most of the time irrecoverable spin the 190 enters sometimes.... 

Edited January 18, 2016 by Herr_Target

[Dr_Molenbeek]

I look fwd for it to Hairy... was just a joke that post of mine :-)

 

And I still do not like the induced snap-roll followed by inverted, most of the time irrecoverable spin the 190 enters sometimes.... 

 

I apologise then.

 

I tend to take things too often in the first degree, on this forum...

Edited January 18, 2016 by Ze_Hairy

[6./ZG26_5tuka]

Sry for driving this offtopic but what do they intent to rework for the Bf109?s Vne, wing flutter at high speed or both?

(Sry, but google translator is pretty cheesy when it comes to technical things and sayings).

[Dr_Molenbeek]

Sry for driving this offtopic but what do they intent to rework for the Bf109?s Vne, wing flutter at high speed or both?

(Sry, but google translator is pretty cheesy when it comes to technical things and sayings).

 

Current state: Shaking starts at 800km/h and Vne is around 850km/h

 

After changes: Shaking will start at 700km/h and Vne still around 850km/h

[Kurfurst]

It would give me a really hard time to refind the post... since it was on russian forum. 

 

EDIT: Done.

 

Bf 109s: http://forum.il2sturmovik.ru/topic/2965-voprosy-razrabotchikam-2/?p=329653

 

Russian fighters: http://forum.il2sturmovik.ru/topic/2965-voprosy-razrabotchikam-2/?p=330512

 

People asked for Fw 190A-3, but NOPE, totally sikret dokumjants.

 

Its nice to see the Devs build so strongly on the historical documents I made available publicly on my site and ignore some pseudo science spouted around on these boards by frustrated individuals.

[6./ZG26_5tuka]

Current state: Shaking starts at 800km/h and Vne is around 850km/h

 

After changes: Shaking will start at 700km/h and Vne still around 850km/h

Thx for clarifying that. So Vne will not be increased at all.

 

I wonder if they use the gernan Bf-109 dive test evaluation report (availabel in english, too) for modeling the high speed appearances of overstress.

 

Would be nice to see a similar effect for other planes as well wheb approaching Vne. The only feedvack we got right now is that controll surfaces are ripping off, which is quite weak.

Edited January 19, 2016 by Stab/JG26_5tuka

[SR-F_Winger]

So all thats being corrected is nerfing german planes. Awesome:P

[Kurfurst]

Thx for clarifying that. So Vne will not be increased at all.

 

I wonder if they use the gernan Bf-109 dive test evaluation report (availabel in english, too) for modeling the high speed appearances of overstress.

 

Would be nice to see a similar effect for other planes as well wheb approaching Vne. The only feedvack we got right now is that controll surfaces are ripping off, which is quite weak.

 

I am not sure if the engine is capable of simulating such depths - in the old Il-2 there was a Vne limit too, then pieces started to fall off. However in real life each plane will behave differently and the stresses come from the planes uniqie flight behavior at high speeds, and also maintenance issues, such as that the then used tailplane grease tended to freeze up and lock the tailplane. The 109F tested for example demonstrated dutch roll oscillations (in conjunction with the modified tail that was being inspected in those tests) and aileron overbalance (which might be a trait of that individual plane though, other tests I have with modified ailerons claim that no overbalance was observed).

 

Maybe a hybrid solution could be to script such behaviours, such as Dutch Roll, elevator ineffectiveness above certain Vne, control reversal, nose tucking etc. and assign such "traits" to each aircraft near VNe. But this also leads to documenting issues.

[Guest deleted@50488]

Yesterday I tried with the G2, and surely there was some intense stick shaking when approaching Vne, and probably flutter too ...

[6./ZG26_5tuka]

Whatever they plan for it I have not found any evidence about "shaking" yet. The Höchstgeschwindigkeit test I mentioned says that the 109 with F model fuselage and G wings showed roll and yaw unstability above pretty much 650 km/h. Exchanging the tail fin with an enlarged one (which was later used as standard for G and later models) improved the instability at the lower end of high speed flight.

 

So if modeled correct, the Bf109 G should offer better controllebility at high speeds. I hope this is being taken into consideration.

 

I'd also like to know more about the rudder changes" biavlov mentioned some while ago.

Edited January 20, 2016 by Stab/JG26_5tuka

[303_Kwiatek]

Wonder if any changes will also affect russian planes?

[MiloMorai]

Exchanging the tail fin with an enlarged one (which was later used as standard for G and later models) improved the instability at the lower end of high speed flight.

 

 

That should be the G-6 and later models but even then the small rudder and large rudder could be found in the same WNr production batches of the G-6. The G-14 had a mix of rudders.

[Dr_Molenbeek]

I do not understand russian and hence need to rely on google translate, maybe some of you can help me out. But when I translate Hairy's link to Han's decision to decrease the limit of shaking by 100km/h (!!), I get the strong impression that this is based on anecdotal evidence. Please help me out and show me I am wrong - otherwise that would mean, anecdotals are valuable in the russian forum section although they are refused and ignored here.

 

(It is off topic, I know. For that, PMs are welcome, too)

 

The post of Han that i've linked, is a reply to a guy that made a report about 109s Vne being too high (claiming that 109s should rip at about ~750km/h, since this speed is know to be their top safe speed).

 

Han replied with some anecdotes of Finnish pilots (mainly), with their 109s that have reached ~850km/h IAS in dive.

 

IMO a Vne of ~850km/h is ok, and the decision to make shaking start at 700km/h rather than 800km/h is a good decision.

Edited January 20, 2016 by Ze_Hairy

[Crump]

BMW801C leistungen:

 

 

Soviet Test Power Settings:

 

 

вэлетная мощнос мотора = Engine Take Off Power = Start-u-Notleistung = 970mmHg @ 2700U/min = 1.32ata @ 2700U/min

 

970mmHG = 38.189121inHg = 1.32ata @ 2700U/min

 

 

номинальная мощность мотора = Rated Motor Power = Steig-u-Kampfleistung = 935mmHg @ 2400U/min = 1.27ata @ 2400U/min  

 

(This is the power setting for the VVS FW-190A4 climb performance...WHY is the climb performance at normal rated power of 1.32ata being compared to the lower power setting performance???)

 

935mmHg = 36.81inHG = 1.27ata @ 2400U/min

 

 

максимальн (одноминутнау) мощность мотора =  Maximum (One Minute) Power = Nothing in the German Fighter Engine Rating scheme.....???Bomber Engine Rating??? = 990mmHg @ 3000U/Min = ????

 

 

 

 

IMO a Vne of ~850km/h is ok, and the decision to make shaking start at 700km/h rather than 800km/h is a good decision.

 

The Vne of the aircraft is listed plainly in the Operating Instructions.  

 

While I have no doubts that pilots saw "850Kph" on their airspeed indicators the fact is airspeed measurement in the 1940's at those speed was wildly inaccurate.  That does not mean the Aircraft exceeded Vne by a wide margin.  The fact the pilot survived the excursion past Vne is evident he did not exceed it by any large margin at all.

[6./ZG26_5tuka]

Noteable airspeed indicator errors were present for all aircraft back in WW2 and leaves too much room for speculation to be modeled accurately in full detail. In the Hochgeschwindigkeitstest pilots dived as fast as 800km/h. The test was not to measure Vne (which is a pretty terrible idea) but to determine coombat effectiveness and nessecary design changes at speeds above max permitted manual speed (750km/h).

Edited January 20, 2016 by Stab/JG26_5tuka

[Crump]

Noteable airspeed indicator errors were present for all aircraft back in WW2 and leaves too much room for speculation to be modeled accurately in full detail. In the Höchstgeschwindigkeitstest pilots dived as fast as 800km/h. The test was not to measure Vne (which is a pretty terrible idea) but to determine coombat effectiveness and nessecary design changes at speeds above max permitted manual speed (750km/h).

 

 

He did not reach 800kph IAS at anytime during that test.

 

 

You cannot make the claim he dove to 800kph IAS.  Once again, Vne is set by very real and adverse behaviors. 

[6./ZG26_5tuka]

Yea I think I got thinngs mixed up with the Vw graph a few pages after, my bad. Was not at home so I couldn't recheck.

 

Still we know finnish pilots claimed to have reached as high airspeeds in their 109s.

Edited January 20, 2016 by Stab/JG26_5tuka

[Crump]

No Issue's and we all make mistakes.

 

Ze_Hairy....

 

I notice your climb test is at 1.32ata @ 2700U/min.  That is too much power and will not match the Soviet Test's.

[Dr_Molenbeek]

Ze_Hairy....

 

I notice your climb test is at 1.32ata @ 2700U/min.  That is too much power and will not match the Soviet Test's.

 

Is this ironic ? I don't get it...

 

Well anyway, if i trust what you said about settings that Soviets used for climb test (A-4) --> 1.21 ata/ 2400 RPM, at a weight of 3990 kg

 

It means that:

 

 

In BoS, at 1.32 ata/ 2400 RPM and 3850kg, you get ~11,5m/s when you reach the 2nd supercharger speed level. And ~11m/s at 3970 kg.

 

We see that in the Soviet test, the plane reaches 11m/s at about the same level, but... at 1.21 ata/ 2400 RPM and 3990 kg...

 

Well, i'll hang myself.

[Crump]

 

 

In BoS, at 1.32 ata/ 2400 RPM and 3850kg, you get ~11,5m/s when you reach the 2nd supercharger speed level. And ~11m/s at 3970 kg.   We see that in the Soviet test, the plane reaches 11m/s at about the same level, but... at 1.21 ata/ 2400 RPM and 3990 kg...   Well, i'll hang myself.

 

 

 

Looks like someone has used the measured data point for performance at 1.27ata as the performance for 1.32ata.   

[Dr_Molenbeek]

Looks like someone has used the measured data point for performance at 1.27ata as the performance for 1.32ata.   

 

Definitely plausible, since the plane ingame at 3970kg and combat power reaches a "peak climb" of ~14,6m/s (if not less) iirc. Now look at the Soviet chart...

 

EDIT: Soviet test was made at 1.21 or 1.27 ata ?

Edited January 23, 2016 by Ze_Hairy

[Crump]

Definitely plausible, since the plane ingame at 3970kg and combat power reaches a "peak climb" of ~14,6m/s (somewhere between 14,5 and 14,7m/s). Now look at the Soviet chart..

 

14.6m/s at 1.32ata?? 

 

If so, then that would potentially make the entire FM underpowered, btw.

 

In the F = Ma of newtonian physics, there is not enough Force in your FM....Patawan!  LOL

Edited January 20, 2016 by Crump

[Kurfurst]

 

The post of Han that i've linked, is a reply to a guy that made a report about 109s Vne being too high (claiming that 109s should rip at about ~750km/h, since this speed is know to be their top safe speed).

 

Han replied with some anecdotes of Finnish pilots (mainly), with their 109s that have reached ~850km/h IAS in dive.

 

IMO a Vne of ~850km/h is ok, and the decision to make shaking start at 700km/h rather than 800km/h is a good decision.

 

 

Agreed. Yawing/Rolling instability was appearantly caused by then insufficient vertical stabliser size on early/mid 109 - later ones with the final tall tail had their Vne increased to 850 km/h (IAS/TAS at low altitudes, progressively decreasing with altitude, roughly corresponding with Mach numbers).