Author Topic: Fw190 D-9 2.03 ata (Read 6973 times)

MANDO · « **Reply #15 on:** April 04, 2005, 07:55:51 AM »

Naudet, calculated or not, there is something named "sonder Notleistung mit A lader Bodenmotor" or something like that (hardly readable). I suppose this is not a "calculated" powersetting, but an actual powersetting. Question would be whether this was operationally allowed during 1945.

Naudet · « **Reply #16 on:** April 04, 2005, 08:12:37 AM »

Mando, we are kinda beating a dead horse hear. The curves are all calculated.
It doesn't matter that the power settings did exist (in case for curve 1, 3 & 5) or where a proposal or may have existed.

I draw a very straight line between documented facts and "wishful thinking".

D9s using 2.02ata belongs in the "wishful thinking" category, as with the current source situation it is not possible to prove the testing of such a setting nor the operational use.

If in the future documents turn up that show such a power settings as operational, i will be the happiest Dorphile around and i surely will search for them in the archive.
But unless i have it black on white i will not speculate.

mw · « **Reply #17 on:** April 04, 2005, 08:48:22 AM »

Hallo Naudet:

Interesting work. Could you cut to the chase for me and describe, in your view, that curve which best represents performance of the 190 D in operational service? Thanks. I've found very similar issues with late 109s as you have encountered with the 190 Ds.

Mike

Naudet · « **Reply #18 on:** April 04, 2005, 08:54:22 AM »

Hi Mike, check your PM box in the allaboutwarfare boards.

HoHun · « **Reply #19 on:** April 04, 2005, 05:26:51 PM »

Hi Mike,

>Could you cut to the chase for me and describe, in your view, that curve which best represents performance of the 190 D in operational service? Thanks.

Have a look at this:

http://hometown.aol.de/HoHunKhan/Fw190D-9Analysis.gif

The blue curve is extrapolated from flight tests, combining the drag factor of a Fw 190D-9 tested in a close to finalized configuration with a sub-standard engine with the power curve from a standard engine.

(It's conservative as the substandard engine is assumed to give full power albeit at a lower full throttle height.)

So the blue curve is a pretty realistic estimate of minimum Fw 190D-9 performance with a 2100 PS (MW50 injection) engine without bomb rack.

Curve 4 is the Focke-Wulf estimate for a Fw 190D-9 with a bomb rack. That's quite a bit faster than my extrapolation, but it makes sense as the Focke-Wulf estimate probably includes the engine compartment seal that the aircraft I based the blue curve on didn't have. I believe Naudet could find no documentation on whether this seal was ever fitted to operational aircraft.

Based on curve 4 and my rendition of it (note slight deviation at low altitude), I have tried to match curve 3 by increasing engine output.

I found that I needed 2400 HP at sea level to achieve curve 4 performance. (Some guesswork involved, but it shows the order of magnitude.) Higher power also yields higher exhaust thrust, which is not indicated in the power curve but plays a big role, too.

My conclusion from this analysis is that curve 3 probably is for a Jumo 213A engine that is run at such a high boost that it doesn't use low gear because low gear full throttle height is below sea level.

Whether such an engine was ever built is not clear, but in my opinion it's highly unlikely that it ever saw operational use. Von Gersdorff et al. list a Jumo 213S engine that was a project for low full throttle heights, yielding a maximum power of 2400 HP, which looks like it could be the engine curve 3 is based on.

Regards,

Henning (HoHun)

mw · « **Reply #20 on:** April 04, 2005, 06:11:40 PM »

Hello HoHun:

Thanks for sharing your analysis. Its very nicely thought out and concisely presented. Strikes me as being perfectly plausible. I have a much clearer picture now of the factors that you fellows have been grappling with in your deliberations. That's strong performance...

Regards,

Mike

MANDO · « **Reply #21 on:** April 05, 2005, 02:06:53 PM »

Quote

Originally posted by Naudet
but also the accompanying pages which show the calculations.

Naudet, these calculations use real plane/engine data as input parameters, or parameters are estimate values?

HoHun · « **Reply #22 on:** June 08, 2005, 05:41:27 PM »

Hi again,

http://hometown.aol.de/HoHunKhan/Fw190D-9Analysis.gif

>I found that I needed 2400 HP at sea level to achieve curve 4 performance. (Some guesswork involved, but it shows the order of magnitude.) Higher power also yields higher exhaust thrust, which is not indicated in the power curve but plays a big role, too.

>My conclusion from this analysis is that curve 3 probably is for a Jumo 213A engine that is run at such a high boost that it doesn't use low gear because low gear full throttle height is below sea level.

I'd like to suggest a slightly amended interpretation of the data we have in order to eliminate some of the "guesswork" I mentioned above. My guess was that the engine in question had the same high-altitude characteristics as the standard Jumo 213.

In order to get the high-altitude speed of my extrapolation to match the high-altitude speed of curve 3, I assumed that the curve 3 aircraft had somewhat more drag at the same power, and worked from there.

My new suggestion: The curve 3 aircraft has the same drag as the standard Dora, but the supercharger gearing has been changed to operate the supercharger at a lower speed, yielding better low-altitude power at the cost of decreased high-altitude performance.

(This is comparable to what was done to the Spitfire LF V with "cropped" supercharger, though in a slightly different way.)

It might be possible to confirm that from looking at the boost levels, though I don't have good data on these.

I admit the difference to my previous interpretation is somewhat subtle, but I think it's a progress anyway :-)

Regards,

Henning (HoHun)

niklas · « **Reply #23 on:** June 09, 2005, 06:03:37 AM »

Quote

Originally posted by HoHun
I found that I needed 2400 HP at sea level to achieve curve 4 performance. (Some guesswork involved, but it shows the order of magnitude.) Higher power also yields higher exhaust thrust, which is not indicated in the power curve but plays a big role, too.

I´m convinced that it is for 2600PS. The difference of 2400 to 2240PS is not enough to give the extra power by exhaust thrust which would be necessary to reach 640km/h. Furthermore, due to the higher critical altitude compared to curve 2, you lose compared to the first stage of curve 2 power in the supercharger. Additional losses due to higher mach number all over the aircraft makes 2400PS look too low also.
In the book "Flugmotoren and Strahltriebwerke" 2600PS is mentioned as a projekt in the last days, i´m sure that curve 3 is for that project.

niklas

mw · « **Reply #24 on:** June 09, 2005, 07:02:15 AM »

Hi HoHun:

>"The blue curve is extrapolated from flight tests"

Flight tests of which aircraft? What speeds were achieved at what boost?

Thanks.

Naudet · « **Reply #25 on:** June 09, 2005, 01:20:38 PM »

Niklas, the document i mentioned in the AAW boards include curves for a FW190D9 with a JUMO213 using C3 fuel. Those speedcurves match with the powercurves and power seetings listed on the JUMO213 chart with the 2240PS curve. That D9 was calculated for roughly 620km/h SL using C3 + MW50 injection.

And none of the Junkers doc i found in Munich ever mention 2600PS as the next projected power for the JUMO213. "Flugmotoren und Strahltriebwerke" is a little bit of in that regard.

The most promising engine according to Junkers was the JUMO213J, an engine with four valves technique and a rated power of ~2400PS@3700rpm@1,6ata. That engine ran succesfully on the benches btw.

HoHun · « **Reply #26 on:** June 09, 2005, 01:52:26 PM »

Hi Niklas,

>The difference of 2400 to 2240PS is not enough to give the extra power by exhaust thrust which would be necessary to reach 640km/h.

Note that curve 4 sea level speed is achieved at 2100 PS, so curve 3 benefits from a 14% shaft power increase, not from a 7% power increase as you assume.

(Naudet found out that we had always used the wrong power curves originally, that's why we had so many problems making it fit.)

>Furthermore, due to the higher critical altitude compared to curve 2, you lose compared to the first stage of curve 2 power in the supercharger.

Curve 2 actually is for C3 fuel - I'm basing my estimate on curve 4 which is based on B4 fuel, just as curve 3.

I'd guess the better performance evident in curve 2 is probably due to using a higher compression engine with the same boost as curve 4, but I haven't thought too hard about it yet :-)

>Additional losses due to higher mach number all over the aircraft makes 2400PS look too low also.

Definitely not :-) Mach number at sea level is only 0.55, far below the critical realm. Curve 3 tops out at Mach 0.60 at around 3600 m.

(The Mach-induced loss of propeller efficiency is figured in by my spreadsheet, and it does in fact play an important role. Before I included it, I actually thought 2100 PS should be enough for 640 km/h, but I was wrong there.)

>In the book "Flugmotoren and Strahltriebwerke" 2600PS is mentioned as a projekt in the last days, i´m sure that curve 3 is for that project.

I'm pretty sure my calculation is accurate enough to rule out 2600 PS. I got within 1% of the flight test speed data, so for a single point, I should be within 3% of the power. So it's really 2400 PS +/- 70 PS - and that's the worst case error, I have a complete speed over altitude curve instead of a a single data point after all.

The same book you quoted also mentions the Jumo 213S with 2400 PS, and in my opinion, there can be no doubt that this is our curve 3 engine.

Regards,

Henning (HoHun)

HoHun · « **Reply #27 on:** June 09, 2005, 02:06:23 PM »

Hi Mike,

>>"The blue curve is extrapolated from flight tests"

>Flight tests of which aircraft? What speeds were achieved at what boost?

Here's the full story of the analysis:

http://p069.ezboard.com/fluftwaffeexperten71774frm9.showMessage?topicID=372.topic

I used flight tests of three different aircraft with end-numbers 002, 006 and 043.

I don't have the boost figures ready because the Jumo 213 was not regulated for constant boost, but for constant charge mass, making boost a parameter of secondary importance. (For example, high gear and low gear boosts were markedly different, and the maximum boost varied even below full throttle height.)

Maybe Naudet can help with the exact figures?

Regards,

Henning (HoHun)

Wotan · « **Reply #28 on:** June 09, 2005, 04:49:19 PM »

Naudet posted this over on Butch's AAW2:

Quote

There it was a package from the NASM, truely amazing as i ordered just four weeks ago.

And the day got even better when i quickly read a frist time through the pages, cause they not only contained the performance numbers/curve i expected. No there was testflight data for the FW190D9 Wk.-Nr. 210 002 with both "Erhöhte Not-/Startleistung" and with MW50 injection!

We finally have it, real flight test speeds for a Dora with the Special Emergency power settings.

Last I read he was busy with real life but once he gets settled he said he would post some info...

Guppy35 · « **Reply #29 on:** June 09, 2005, 09:11:44 PM »

Don't think this is hijacking the thread since it's D9 related. I came across a used copy of Dietmar Hermann's book on the FW 190 "Long Nose"

I assume this is the book Naudet is referring to up thread a ways as a good source on the D9-D13.

A couple of questions after having gone through it.

My impression was that there were very few if any D12s that made it to combat units and only a couple of D13s including the surviving Yellow 10.

Is this a fair assumption?

Also, how many D11s were produced and saw combat? I couldn't find that info in the book

I was also surprised to read about the test flights flown by German pilots in the D13 including the one against the Tempest a month after the war was over.

First to admit my LW knowledge is far below my RAF and USAAF knowledge, but always trying to learn more

Dan/CorkyJr