Fw-190 vs Spit/P-51/P-47

[Soren]

Although the round engines were more robust, they could be a lot more difficult to work on (I say that from experience).

And I 2nd that ! Having worked on Radial engines before I know it can be a real pain in the *** just having to change the sparkplugs.

[Jank]

From a poster on THE GREAT PLANES forum:

THE GREAT PLANES Community - P-38 Lightning as Long-Range Escort

Data on flight hours and labor hours on these engines. I have no idea where it came from so take it with a grain of salt.

1945 1st quarter

V-1650
flying hours: 302
labor hours: 251

V-1710
flying hours: 362
labor hours: 134

R-2800
flying hours: 580
labor hours: 147


1945 2nd quarter

V-1650
flying hours: 200
labor hours: 259

V-1710
flying hours: 387
labor hours: 153

R-2800
flying hours: 500
labor hours: 241

[Jank]

P-38J tests with 44-1 fuel:

P-38J Performance Test

VII CONCLUSIONS

c. The maintenance difficulties experienced throughout the tests were considerable. These consisted mainly of induction, exhaust system, and spark plug failure. However, these difficulties could not be attributed directly to any action of the 44-1 fuel.

VIII RECOMMENDATIONS

a. Because of the mechanical and maintenance characteristics of the engine and the P-38J installation this rating should be limited to a very short time. Periods between overhaul should be shortened for the engines using this power.

[Jank]

P-47D tests with 44-1 fuel:

P 47D Performance Test

The issues with the P-38J do not appear present and there is no mention of shorter intervals between overhauls.

[Parmigiano]

Back to the original topic, I just want to add my 2 cents of common sense:

Spit IX vs P51: they shared the same engine (actually we could take the Spit XVI that was basically a IX with a Packard-Merlin), but the Spit was about 1400 pounds (empty) or 5000 pounds (full load) lighter.

It seems very unlikely that the P51 could have delivered the same performances of the IX, even if we assume that the aerodynamic design of the P51 was MUCH better than the Spit (that is, at least, a very bold assumption)
In general, we can say that the wing design allowed the Mustang a higher cruise and top speed, but at further expense of lift and other positive parameters.

From the RAF report (source: Spitfire, Alfred Price) the comparison between a Spit IX and a Fw190 (I think was the same A3 or A4 previously compared with the Spit V) revealed a substantial tie between the 2 aircrafts, the main differences being the tight turn (advantage for the Spit), the roll rate (for the Fw190) and the zoom dive (Fw190).

This test was made up to 25000 ft, above that height we know that the drop in power of the BMW801 was impacting the 190A performances

Since during production there were thousands of micro-changes, on-going improvements etc., it is impossible to rationally say or deny that 'a certain version of XX was a bit better than a certain subtype of YY' but in terms of
'macro differences' (and a weight difference of 25% in the best case is a macro difference) the above considerations should be a fair assessment of the relative performances of the 3 aircrafts.

Another 'general common sense' consideration: if the Fw 'A' pilots were experiencing a serious lack of performances in dogfight, they had an easy way to improve handling and performances, that is to remove the outer Mg151 saving about 3-400 pounds and retaining enough firepower to shoot down any enemy fighter.
I am not aware that there was an official 'U' or 'R' specific configuration of this kind, and considering the appassionate love of the Germans for classification I think it is safe to assume that this change was not felt as necessary by the Luftwaffe.

[Soren]

Parmigiano, the Fw190 tested by the British suffered severe engine troubles as-well as aileron adjustment-difficulties which significantly influenced the test-flight-results with this particular a/c - A decrease in power seriously affects both turn and climb performance, and obviously it also affects speed quite dramaticly. The improper adjustment of the ailerones affected turn rate dramaticly, causing premature departures in tight turns.

Also Spitfire IX pilots, despite the availability of increased performance, certainly didn't speak to positively about their own chances when faced by FW190's over the channel.(Despite what some test report might tell you) And according to FW190 pilots, they frequently accepted turn-fights with the Spitfire and came out on top - ofcourse the Spitfire did have a tighter turn radius, but for the first 1/3 of a 360 degree turn the FW190 actually turned abit faster, and combined with its superior energy retention this made the FW190 a truly nasty opponent for the Spitfire in a dogfight.

[Jank]

Soren, while your point is well taken, I do not believe it is accurate to characterize the engine problems as "severe."

[Parmigiano]

Soren and Jank,

to summarize the story:
if my 'common sense' is correct we should have
1 - Spit IX and Fw190
3 - P51

if your comments are correct we should have
1 - Fw190A
2 - Spit IX
3 - P51
at least up to 25000 ft

... quite a strong statement !

[wmaxt]

Originally Posted by Jank

Can you share where you saw that "it has been reported that it also wore out most quickly to an overhaul/war weary status"?

I am interested because I have read an account from a crew chief (I wish I had it to share) that indicated that the R-2800 could go longer between maintenance intervals than the Merlin powered Mustang - I think, in part due to the spark plug problems suffered by the Mustangs but I'm not sure.

I have also read in The Report on Joint Fighter Conference 1944 that the mechanical maintenance on the P-38 was more complicated and troublesome.

I don't know where it originated, where did I read it? I can't tell you that, either, I didn't note the source at the time because I didn't put any credence to it until I had seen it several times, sorry. Since I don't know the source I consider it a possibility only at this time. If anyone else has info on this we'd like to hear about it.

The P-38 was very closely packed and could be very tough to work on. Someone here posted a cutaway drawing, on this forum, of the P-38 and its quite an eye opener.

As for the Joint Fighter Conference report, I don't know the mix or the conditions. Was there an experienced P-38 crew and pilot there, that could make a huge difference in the perception of the aircraft. How about proper facilities, spares etc.? I've seen Navy comparisons where the AAF aircraft were flown and compared with Navy aircraft using METO power settings against 70" in the Corsair. To add insult to injury the Corsair had its stores pylons removed and faired over while the P-38s are fixed (even the show plane Yippee has its pylons, they weren't removable). Maintenance wise I've heard both sides of the same coin. Typically the newer mechanics found the P-38 very daunting and difficult it was so densely packed and a lot of the systems were fairly new in the war years. For instance it was the first with hydraulic ailerons. Once the systems and proper techniques were worked out it wasn't much different than anything else. Art Heiden flew his P-38 320 combat hours on the same engines and didn't miss any mission time due to maintenance. Given proper maintenance and treatment the P-38 was as good as they got in WWII. On the other hand jam the throttles forward before the mixture was richened and your going to have a dead stick landing so you better start pumping the landing gear down !

wmaxt

[Soren]

Originally Posted by Jank

Soren, while your point is well taken, I do not believe it is accurate to characterize the engine problems as "severe."

They were quite severe for the outcome of the test-flights, as available power was well under the normal output.

[Jank]

Parmagiono said, "Soren and Jank ... if your comments are correct we should have
1 - Fw190A
2 - Spit IX
3 - P51
at least up to 25000 ft"

My comments do not lead to that conclusion. All I said was that I thought Soren's characterization of "severe" engine problems was excessive. I have read that test and there were engine problems. No, they were not "severe." I was not passing judgement on your common sense judgement.

Bottom line - if you are conducting a flight test and experience "severe" engine problems, you immediately land. If you continue on with the test, that is definitive evidence that the problems did not rise to the level of "severe."

[DerAdlerIstGelandet]

Originally Posted by Jank

Bottom line - if you are conducting a flight test and experience "severe" engine problems, you immediately land. If you continue on with the test, that is definitive evidence that the problems did not rise to the level of "severe."

That is correct....

[Soren]

I apologize for not making myself clear enough Jank, what I meant, as I wrote in my last post, is that the engine troubles proved severe for the outcome of the test - I admit calling the actual engine troubles "severe" (although they were serious for the testing), is rather excessive indeed, I hope you accept my apology.

From the British report:
There are indications that the engine of this aircraft is de-rated, this being supported by the pilot's instruction card found in the cockpit. Further performance tests and engine investigation are to be carried out by the RAH and more definite information will then be available.

Throughout the trials the engine has been running very roughly and as a result pilots flying the aircraft have little confidence in its reliability.

[Parmigiano]

Jank, sorry for having misunderstood your comment, my perception was that you were meaning 'that 190 was not in optimal condition although not to the extent implied by Soren'

Rather than establishing an order, I am more interested about the 'common sense statement', I think it is the interesting part of the discussion, so I try to rephrase it :

Is it possible that an aircraft who is (in the best possible case) 25% or 1400 pounds heavier than another aircraft - who is widely recognized as one of the best performing of the era - and share the same engine can have overall equal or better performances?

We are not talking about tactics, sheer numbers, easiness of construction, we are talking about flight performances.

Based on rational thinking, I would say 'no way' for every machine, aircraft, GP motorbike or F1 racing car.
I can accept that a more refined airframe design can cope with a 5-10% weight handicap, not with a difference of this magnitude.

I would like to have this concept challenged with rational reasons, pilot reports are too often biased, even if in 'bona fide'.

For instance, I rationally accept that the heavier craft can be faster because of a different wing airfoil, but I also rationally assume that (since in physics nothing is free of charge) that airfoil optimized for low drag is paying fee in terms of lift and other parameters, further enhancing the gap vs the lighter machine in performances like climb and turn.

I.e. rational reasons could be:

- the assumption is wrong because the real weight data are different and the real difference is only 200 pounds
- The propeller of the P51 was much more efficient than the Spit, so the P51 was more efficient in trasforming power in thrust.
- Weight is not really an important parameter for flight performances (but in this case why? this would be a revolutionary concept)
- The Packard-Merlin was in reality a substantial improvement vs the RR Merlin

Sorry for bothering, but I am really curious...

[FLYBOYJ]

Originally Posted by Soren

And I 2nd that ! Having worked on Radial engines before I know it can be a real pain in the *** just having to change the sparkplugs.

I bet you and I have the same scars on our knuckles!