[CLOSED] Climb rate appears to be to high, even for 109k

[NineLine]

Full power, although understand at full power the effect is lessened substantially... that said, ED's pilot described that it was flown just under max (non-boost) power most of the time, only using full if absolutely needed, so that's how I *try to* fly ;)

Edited May 19, 2015 by NineLine

[Hummingbird]

The Spanish Buchon apparently climbs at 5,580 ft/min with a 1,680 hp Merlin engine at a weight of 3,200 kg.

 

This leads me to believe that climb rates were measured abit differently by the Germans.

[Echo38]

The Spanish Buchon apparently climbs at 5,580 ft/min with a 1,680 hp Merlin engine at a weight of 3,200 kg.

 

 

Where did you hear that?

[NineLine]

Topic is about the DCS Bf 109K-4 and the issues with the climb rate, lets not start down the chest puffing path...

[Yo-Yo]

YoYo,

 

Is it possible in your opinion that the Mtt Projektbüro calculations do not include exhaust thrust, as it appears to be the case in the Fw D9 calculations?

 

It's very plausible. To calculate exact rate of climb with accuracy higher than, say, 10% you have to know exact jet thrust and radiator drag. Even not saying a word about exact prop efficiency measurement.

I still have not seen any evidences that they took all this factors in account.

[NineLine]

To OP, this has at the very least been fixed internally. I am not sure if its made it into release yet, but you should be seeing 25-26 m/s initial if it has.

[Pilum]

It would be interesting to compare this result for 3400 kg and ~1850 hp of the 109 to the test of 3850 kg Mustang having the same power at 75 "and giving 23.6 m/s climb, even more than you estimation gives for 109.

 

http://www.wwiiaircraftperformance.org/mustang/na-p51b-150grade-climb.jpg

 

Or to compare to this test

http://www.wwiiaircraftperformance.org/mustang/p-51b-24771-climb-blue.jpg

for the mass of 9680 lbs ( 4400 kg) - 22.4 m/s less than 1 m/s slower than 3400 kg plane of the same power.

 

I do understand the difference in prop diameters, L/D ratio, etc, etc.... but 1000 kg advantage for the Mustang? Do you really believe that it's possible?

 

Since this is OT I will not delve in it but yes I agree this looks optimistic and I would expect lower climb rates for the P-51 under these circumstances.

[Pilum]

YoYo,

 

Is it possible in your opinion that the Mtt Projektbüro calculations do not include exhaust thrust, as it appears to be the case in the Fw D9 calculations?

 

It's very plausible. To calculate exact rate of climb with accuracy higher than, say, 10% you have to know exact jet thrust and radiator drag. Even not saying a word about exact prop efficiency measurement.

I still have not seen any evidences that they took all this factors in account.

 

Well on this we have to disagree: Exhaust thrust is included in my calculation and without it the climb rate for the K4 at 1.8 ata would be around 21.5 m/s i.e. 1.8 m/s lower. So since exhaust thrust has a significant effect on the climb rate I have no doubt whatsoever that neither Focke-Wulf nor Messerschmitt would publish a climb chart without this effect included but I’m wiling to stand corrected if proof to the contrary can be produced. :)

[Solty]

Since this is OT I will not delve in it but yes I agree this looks optimistic and I would expect lower climb rates for the P-51 under these circumstances.

I thought it would be around 21m/s. I remember reading about it some time ago.(I might be wrong though)

 

23m/s realy does feel optimistic, when we take into consideration that P-51D with 67'hg has ROC of 18m/s at SL.

Edited May 19, 2015 by Solty

[Pilum]

To OP, this has at the very least been fixed internally. I am not sure if its made it into release yet, but you should be seeing 25-26 m/s initial if it has.

 

Good and that is a step in the right direction but still too high IMHO. Anyway, thanks for update!

[Pilum]

I thought it would be around 21m/s. I remember reading about it some time ago.(I might be wrong though)

 

23m/s realy does feel optimistic, when we take into consideration that P-51D with 67'hg has ROC of 18m/s at SL.

 

Yup, I agree and if the P-51 is to have historically correct climb rates then we want the same for the K4 right? :thumbup:

[NineLine]

Yup, I agree and if the P-51 is to have historically correct climb rates then we want the same for the K4 right? :thumbup:

 

And that is what Yo-Yo is doing.

[Pilum]

And that is what Yo-Yo is doing.

 

Targeting 23 m/s? I thought you said 25-26 m/s?

[NineLine]

Targeting 23 m/s? I thought you said 25-26 m/s?

 

Targeting historically accurate performance.

[Pilum]

Targeting historically accurate performance.

Well, I guess that is a goal we all can agree to!

 

Can't wait to see what a historically correct Spitfire Mk9 climbs like though:music_whistling:

[NineLine]

Well, I guess that is a goal we all can agree to!

 

Can't wait to see what a historically correct Spitfire Mk9 climbs like though:music_whistling:

 

I would imagine it will climb like a real Spitfire Mk9 ;)

[Pilum]

Time will tell, time will tell :)

[NineLine]

I'm not worried at all. Anyways. This issue has been fixed, I am just not sure if its been merged with release yet.

[Yo-Yo]

I thought it would be around 21m/s. I remember reading about it some time ago.(I might be wrong though)

 

23m/s realy does feel optimistic, when we take into consideration that P-51D with 67'hg has ROC of 18m/s at SL.

 

I refered not to calculations but to the FLIGHT TESTS. See 75" boost results.

[Kurfürst]

Uhm, Il-2's K-4 was a true beast with 28-29 m/sec climb rate.

 

And its no wonder if you get pessimistic figures for the K if you 'tune it' to the Kennblatt (sic!) figures, given that the Glc datasheet has the DM engined K-4, with much different (weaker) 30-min rating compared to the DCS one with almost 200 hp more..

[NineLine]

Its not only the point about how they built their FMs, but also how much data they collected to do so, that's a question we really cant answer.

 

Bottom line is its Yo-Yo's job to research, collect and interpret all this data and have the FM end up flying like the data shows.

 

SO we are back to the start of this thread, ED has fixed some issues with the 109 that caused the climb rate to be too high, its lower now (at least internally) and they are happy with that, not to say there isn't more tuning to go of course.

[Anatoli-Kagari9]

K4 Climb rate...

 

At another thread which was supposed to be about max level speed of the K4 near MSL, Standard Day Conditions ( I guess ), the topic of climb rates was brought.

 

I had already got lost in the middle of many references, mostly to documents I can't read ( they're in German ) although I can tray to interpret their charts...

 

But, regarding the climb rate on the present state of the beta version of the K4, and since it was apparently overdone when it was initially released, I wonder if it was addressed in any of the patches, because it seems to me it doesn't climb so "fast" as it did before ?

 

Presently is it:

 

1) Still higher than expected Climb rate;

 

2) Lower than expected Climb rate;

 

3) OK!

 

?

[Kurfürst]

Here is the historical Messerschmitt curves for the variant we have - K-4 with DB 605DB at 1,8ata / 2800 rpm (1850 PS)- see first, thick continous line.

 

http://kurfurst.org/Performance_tests/109K_PBLeistungen/Leist_109K_EN.html

 

[Anatoli-Kagari9]

Here is the historical Messerschmitt curves for the variant we have - K-4 with DB 605DB at 1,8ata / 2800 rpm (1850 PS)- see first, thick continous line.

 

http://kurfurst.org/Performance_tests/109K_PBLeistungen/Leist_109K_EN.html

 

 

 

What CAS is used for those tests ?

 

What should I use in DCS to run similar tests ? And, BTW, should I set fuel to 100% and guns to 100% ?

 

Thx!

[Kurfürst]

3400 KG, ie. 100% guns and fuel

full power and MW WEP on (1.8ata manifold pressure, 2800 rpm)

 

Radiators roughly 2/3s open up to 6-7 km.

Above rated altitude (7500) coolant radiators gradually closing, reaching 1/4 open at ceiling (probably could be done on AUTO?)

 

This is the condition the figures on the chart represent.

 

Climb at roughly 270 kph IAS.

Edited December 26, 2015 by Kurfürst