P-51D "Mustang" vs. Fw-190 "Dora"

[Soren]

With proper performing engines the max climb rate of the Dora-9 was 22.5 m/s at SonderNotleistung m. MW50 (2,100 PS @ 3,250 RPM), and at SL, the a/c in the test on Mike's site suffered from a faulty batch of engines and gear issues, something which is noted in the documents.

Climb rate without ETC-504 rack, 22.5 m/s:

Climb rate with ETC-504 rack, 21 m/s:

 

[FLYBOYJ]

the a/c in the test on Mike's site suffered from a faulty batch of engines and gear issues, something which is noted in the documents.

How were they faulty?

 

[Juha]

hello Soren
gives the book indications are the info based on calculations or test flights. At least the first one is IMHO calculated, IIRC no Ta-154C-3s ever flew.

Juha

 

[drgondog]

I have a tendency to not discount calculated performance when the primary difference is related to one variable (i.e potential change in speed due to horsepower boost, or possible all same except new wing).

Performance calcs on a new airframe, however, is a 'hopeful' until flight test results validate/refute the dream.

 

[vanir]

Plus the initial climb rate at sea level is a little different to initial climb at 2000 metres, the best performance height of the Dora in the low gear (1800m with use of MW50 is best).
My output ratings are estimates, given ratings for early tests of the Jumo 213A at sea level (again from actual flight testing of early production Doras) at 1.68atm return ~1780PS no MW50 (which was not fitted back then), and for use of low pressure MW50 (mounted in the supercharger intake) at 1.76atm for 1900PS. For the use of high pressure MW50 tested in early 1945 (mounted in the supercharger exhaust) the Jumo is rated for 2000PS at 1800m.

My estimate of 1900PS at 2000m and 1.72atm is probably therefore a little generous, it is most likely let's say 1850PS, although the supercharger performance at this height is from actual flight tests conducted in Oct44 of werk number 210002, and it still has a good 250hp over the Mustang flat out at this height before even touching the MW50 switch. Of course against a Mustang you need that

 

[piet]

Sad to say but its the p-51

 

[DerAdlerIstGelandet]

Sad to say but its the p-51

And your reasoning behind your conclusion. Not saying you are wrong, but you might want to tell people why you came to that conclusion.

 

[Milosh]

What was the power output of the Mustang when using 150PN fuel?

The only data I have is for the RM14SM
WEP, 150PN: 2080hp @ 3000rpm @ 80"hg (25lb boost); 1850hp @ 22,500'

 

[drgondog]

What was the power output of the Mustang when using 150PN fuel?

The only data I have is for the RM14SM
WEP, 150PN: 2080hp @ 3000rpm @ 80"hg (25lb boost); 1850hp @ 22,500'

This engine was identical to the 1650-9 except it used a Skinner Fuel Injection system but the 1650-9 was equivalent in rating to the RM16SM.. we are talking about XP-51J and P-51H now as the -9 had more power than the -7.

-9 had 1930 Hp at 80" w/150 octane and WEP at 10,000 ft. IIRC, at 90" it was 2200 with WI at WEP

I'm going to look up the -7 for 75" at WEP for 150 octane.

 

[Mike Williams]

What was the power output of the Mustang when using 150PN fuel?

Here's what I have readily at hand:

1868 BHP at 7400' operating at 75" MP and 3000 RPM.

P-51B-15 AIRPLANE, AAF NO. 43-24777 USING 44-1 FUEL

2,000+ BHP operating at +25 lbs (80"), 3,000 RPM.

 

[Milosh]

Thanks Mike.

The reason I asked was because I believe 150PN fuel was in wide spread use by the Mustangs of the 8th AF. This would negate the 250hp difference stated by vanir.

 

[vanir]

I spent ages going over the various documentation and discussion regarding 150 octane at Mike William's site and you know what I came up with? Everybody was still using 130 grade. But I'll tell you what Milosh, I'll stipulate that all Mustangs in the 8th run at 80" Hg if you'll stipulate that all Doras in Luftflotte Reich use high pressure MW50 reliably.

Fair's fair. But this still brings us right to where we started, where I said the Dora was a competitive contemporary despite its shortcomings according to both the data and the reports.

 

[piet]

The P-51 shot down more germanfighters.....than germanfighters shot down P-51 , so it was better in my Opinion.....its all about the kill ratio.

Allthe best,
piet

 

[Milosh]

I spent ages going over the various documentation and discussion regarding 150 octane at Mike William's site and you know what I came up with? Everybody was still using 130 grade.

150 Grade Fuel Consumption by Theater (Tons)
Consumption of 150 Grade Fuel by Theater (Tons)

Consumption of 150 Grade Fuel - Barrels
Consumption 150 Grade Fuel - Barrels

Did you somehow miss this vanir?

That is almost 74 million gal. of 150PN fuel consumed. (1bbl=35Imp gal)

 

[drgondog]

I spent ages going over the various documentation and discussion regarding 150 octane at Mike William's site and you know what I came up with? Everybody was still using 130 grade. But I'll tell you what Milosh, I'll stipulate that all Mustangs in the 8th run at 80" Hg if you'll stipulate that all Doras in Luftflotte Reich use high pressure MW50 reliably.

Fair's fair. But this still brings us right to where we started, where I said the Dora was a competitive contemporary despite its shortcomings according to both the data and the reports.

Vanir - I thought the same as you - that 130 was used into September - then 150 thereafter.

At our 355th FG reunion last month I cornered the crew chiefs. All recall 150 used from June-July till end of War as well as 1/2 time to run on same plugs w/o replacing them.

150 was in full supply throughout 8th FC by end of July for sure.

 

[DAVIDICUS]

"The P-51 shot down more germanfighters.....than germanfighters shot down P-51 , so it was better in my Opinion.....its all about the kill ratio."

Keep in mind that the Germans were tasked with stopping the bombers too. The Americans were tasked solely with stopping the German fighters.

I suspect that this additional and often primary focus on the part of the Germans accounted for some of the lopsided kill ratio. The Germans would often engage in such a way that American fighters were setting upon them first.

 

[Demetrious]

This post was worth the whole thread, for me, because it gave me some insight into the dynamics of speed as they effected dogfights between these contemporary foes. Roll rate is generally considered the most important axis of manuverability (and for good reason,) and the peak roll rate of 190 degrees of roll/second that old NACA chart shows is absolutely mind bogglingly amazing performance for any fighter of the war.

However, I never considered that 50lbs of stick force might be difficult or even impossible to input at higher speeds, making the peak possible roll rate unavailable in higher-speed engagements. That further solidifies the nature of the fight dynamic between the 190 and the P-51- one wanting to keep the fight fast and high, and the other wanting to slow it down and drag it to lower altitudes.

If there's one thing I have learned by studying WWII aircraft, is that these engineers generally knew what they were doing. Even the "horrible" planes that history has called "unmanuverable" (the F4F, F6F, F4U and P-40, for starters,) or even flat out hopeless (the Buffalo and the I-16) were far more capable then popular knowledge gives them credit for. If even those aircraft had impressive enough performance to put up a good fight, then you can imagine how narrow the margins are between two of the finest fighters produced in the entire war- the P-51D and the FW-190-D. Simply put, the performance margins are far narrower then the skill margins of the pilots.

What shaped the actual battles had more to do with strategy then tactics- i.e, the altitude and situations these fighters were forced to engage at, and which one was on it's "home turf."

 

[vanir]

Vanir - I thought the same as you - that 130 was used into September - then 150 thereafter.

At our 355th FG reunion last month I cornered the crew chiefs. All recall 150 used from June-July till end of War as well as 1/2 time to run on same plugs w/o replacing them.

150 was in full supply throughout 8th FC by end of July for sure.

Cheers. Fair enough. Now that I think about it I was actually looking up RAF deployment of increased boost related to 150 octane fuel and iirc found out it was only about three squadrons of MkIX using it towards the end of 1944 where someone was supposing widespread use of +25lbs in MkIX Spits in 44-45. Not relevant and I'm sorry for the confusion.


Indeed Milosh, comparing say JG26 Doras to 8th AF Mustangs should account for +25-28lbs being used on the Mustangs, which returns around 1900hp at about 2000m WEP or roughly equivalent output in a cleaner airframe. I would still stipulate that the official sondernotleistung rating for the 213A however was ten minutes use without trouble, which is much different to the Me109 sondernotleistung rating during 1944 varying from 1-5min tops before damaging the engine, and the Merlin was rated for 5min WEP normally at +18lbs I'd imagine this wouldn't significantly increase by actually raising manifold pressure.

I still don't see where we should say the Mustang can use +25lbs for comparison but the Dora may only use start u-notleistung with no MW50 when the high pressure system was reliable and in common use during 1945. Initial deliveries Oct-Nov 1944 were a bit different, some with low pressure MW50 or others with the fuel pump operated erhönte notleistung but these definitely aren't in the majority and perhaps it's a bit like me forcing you to compare the Allison P-51 against the 1945 Dora because that was the initial deliveries of the Mustang design.

 

[Milosh]

The 5 min restriction of the Merlin was the recommended time limit but not because it would have a catastrophic failure after 5 min. I can't think of any British or American engine that had more than a 5 min restriction on WEP. To many people read to much into this 5 min restriction.

I am sure drgondog can give you examples of 25lb Mustangs using WEP for much longer than 5 min. I have read about Spitfires using WEP for much longer than 5 min.

Who is comparing 25lb Mustangs to start u-notleistung with no MW50 Doras?

If the Doras were around when the Allison Mustangs were introduced, a comparison could be made but they weren't.

 

[drgondog]

The use of WEP boost excessively resulted in documented engine failures early in the Mustang cycle but they were pretty rare. On the other hand I'm sure pilots exceeded the 5 minutes but I have not read of any documented and accurately recorded upper limits.

I suspect they became rarer simply becuase pilots were warned that you could blow an engine in a place you didn't want to be and you only used it when it a.) might enable you to quickly close on a firing solution, or b) give you enough edge to escape someone else's firing solution.

The 'real' upper limit was probably closer to 7-10 minutes with 5 given as a safety margin - but sure wasn't much above that. At the end of the day how many individual fights lasted more than 5 minutes at full throttle?

My father respected it (the manual) enough to put a hard stop on 67" (fo take off) on his 51 (peace time bird in late 59-61) to make sure I didn't do anything dumb. On the other hand (it has been way too long ago) I think we used 110 in the 1960 era.

Independent of all that MW 50 is necessary to keep the speeds comparable between the 51D with 150 octane and using 72" boost.

I will still remain convinced that tactical situation and pilot skill are far more important than the low % differences between these two ships in equivalent mechanical and fuel purity state.