Trade-offs in WWII Fighter Design

[M.B-5]

Hey Surgeon, I can get how "fresh meat" would be your thing,

- it sure beats hacking on stinkin' ol' corruption-raddled gangrenous rot...

But - if facts can intrude on the niceties fo' a mo', then fo' sure, we can straighten some sheets..

 

You want WW2 piston-power for fighter take-off, forget about a lazy-bones radial, check this intense machine out...

 

http://www.flightglobal.com/pdfarchive/view/1945/1945 - 2284.html

 

&, liquid-cooling allowed that "climbing" power rating to be enabled for an hour, something an air-cooled engine aint doin'

[LostCosmonaut]

Linking to period documents is always a good start, welcome.

[M.B-5]

Cheers, LC. 

You may find some data of interest in this table here too;

 

http://www.flightglobal.com/pdfarchive/view/1947/1947 - 1491.html

 

Note also the fuel efficiency of the sleeve-valve Napier Sabre V, 56.7 gallons per hour making 890hp/2500rpm,

versus the R-R Merlin 500 @ 71.5 gph for 90 hp more at 2650rpm  - while needing another +6.5lb of forced induction boost.

 

For comparison, an earlier Napier, an unsupercharged sea-level DOHC 4V W12 Lion race engine on 10:1 comp ratio made 880hp @ 50 gph.

 

http://www.flightglobal.com/pdfarchive/view/1945/1945 - 1118.html

 

 

[Collimatrix]

16 hours ago, M.B-5 said:

Hi y'all.

 

Some interesting views put forth, here in this thread.

Do allow some corrections, though, won't you fellas...

 

1,The rear "Aux" fuselage tank in the P-51 wasn't actually a "drop tank" - it was for transit flying & was used 1st,

rather than in combat.

2, P-38 did ok against the lesser forces of Nippon, but could not technologically* hack the pace in the ETO,

  & was replaced by the P-51.

3, P-47, like the other P&W R-2800 powered fighters  - was a real gas-hog,  even at a slow cruise speed,

& like the P-38, was dumped by the 8th AF, on the advent of the P-51 - arriving in numbers.

4, P-51 did not need the "dive flaps" belatedly attached to both P-38 & P-47 to recover control,

& pull out safely - from 'Mach crit' high speed dives.

5, Victory stats collected by the USAAF in the ETO, confirmed their top choice of the P-51 as air-superiority fighter,

- was the right one**.

 

* P-38 was a real handful of control complexity to simply fly, let alone operate in combat - esp' against the faster diving 109/190, whose pilots could spot the big twin-boom Lockheed from a distance,

& then choose an attack profile - to suit themselves. 

 

**The RAF wanted all the Mustangs they could get, (even the Allison powered ones, which they used 'til war's end),

but didn't want P-38's, & relegated the hundreds of lend-lease P-47's they received - solely to combat against the lesser forces of Nippon, too. 

 

 

 

 

Hello M.B-5, and welcome to SH!

I am not well-versed in the specifics myself, but I would suspect that plenty of P-38 fans would come forth to defend its honor, even in spite of its shortcomings in the European theater.  Among other things, a lot of the P-38s in combat early on in Europe were the downgraded export models which lacked handed propellers, and, at least according to some sources, received inferior maintenance to P-38s in the Pacific Theater.  P-38 was a very maintenance-intensive bird, and it would not give its best performance if not looked after very carefully.

There were other problems too, like improperly mixed fuel.  The Americans were far, far ahead of other nations in av-gas formulation in WWII, and some of the fuel used in the ETO didn't have the anti-knock agents mixed correctly.  Bottom line was that the V1710s in a combat wing of P-38s were very likely not performing how they would on a test stand in the Indianapolis factory.

By the time the P-51 showed up, these problems were a lot better understood, so in large part the P-51 benefited from a lot of experience gained on earlier models of fighter.

I'm a little curious to know why exactly a Bf 109 could out-dive a P-38.  According to the parasite drag and thrust chart posted before, the P-38 had a very low drag coefficient despite being twin engine.  Might have had something to do with the fairly low Mcrit.

I have been unable to find good specific fuel consumption charts for the most common WWII piston engines, but my book on Allied piston engines claims that the R2800 was in the middle of the pack for efficiency.  True, it did guzzle fuel, but it produced a ridiculous amount of energy while doing so.  The lower fuel consumption of the P-51 vs the P-47 is, I would think, less a function of the Merlin being a more efficient engine than the R2800 and more a function of the Merlin being a much smaller engine than the R2800.

Sleeve valve engines generally had higher compression ratios, so I would expect them to have a modest advantage in specific fuel consumption compared to conventional poppet-valve engines.

[Meplat]

14 hours ago, Sturgeon said:

AHH, FRESH MEAT

Fuck, you have not seen my late granpap angry.

 

 

To re-illustrate for our confused poster...

 

The man already had a mechanics ticket in 1938. When he enlisted.

He was all but thrown out in 1968.

 

So, when I roll in about aviation history, rest assured it's from a pretty unique viewpoint. 

 I have worked on, and restored a number of Ww2 aircraft, and later, armor.

 

So.. When I say "What the fuck are you on about?!?"  it is without malice, but amazement.

[Domus Acipenseris]

No docs in this post, sorry.

 

The P-38 was designed as an interceptor.  As such, it was expected that the pilot could do things like switch fuel tanks, change prop pitch, and adjust the mixture at his leisure.  The main reason for the difference in combat performance between the PTO and ETO was the lack of an Integrated Air Defense System in the PTO.  Japanese interceptors were trying to climb up to reach the American strikes and the P-38's had the advantage in situational awareness and energy.  In the ETO the Germans had the edge in both due to their high quality (for the time) IADS.  The P-38's switchology was too difficult for the average pilot whereas the P-51 gave the pilot a better chance.  Other factors in the P-38's performance in the ETO were lack of experience and relative numbers.  The P-51 arrived when the US had more knowledge and more planes and the Germans had fewer.

 

The P-47 was a better fighter bomber than the P-51 due to greater range-payload and lower vulnerability.  The P-47 was capable of handling the German fighters but at $80,000 a piece vs $50,000 for a P-51 the P-47 had to be used where it was most effective.

 

 

[Domus Acipenseris]

Does anyone have any info. on bubble canopies?  I've read that many pilots preferred the razorback P-47 because it was faster, a more stable gun platform, and easier to escape from if the plane became inverted on the ground compared to the bubble canopy version.

 

Of course, we all know that the F-35 will be clubbed like a baby seal because it lacks a bubble canopy.  The reason the US lost so many planes in Vietnam?  Yes, you guessed it, no bubble canopies.

[Jeeps_Guns_Tanks]

The reason we lost so many planes in Vietnam,  is in the infinite wisdom of the Air Force and Navy leadership decided missiles made ACM obsolete. They then stopped training fighter pilots in ACM. Once they learned the errors of their ways and started teaching ACM again, the K/D ratio went right back up to near Korea War levels, and bubble canopies had very little to do with it. 

 

It's also a bit of a stretch to say the F-35 doesn't have a bubble canopy. 

 

 

 

 

[M.B-5]

P-38 missed out on a bubble canopy upgrade, unlike the P-47, & P-51.

P-47D got an improved windshield & bubble canopy - which was pretty much a straight copy

- from the Hawker Typhoon.

 

When the 'Mighty 8th' cast-off its P-38 & P-47 units for the more effective P-51, the 9th 'tactical' AF got them,

for 'mud-moving' tasks, even though they were expensively optimised for high-altitude work with turbochargers,

& not at their best - down low. 

 

The 9th AF quickly found the P-38 to be too big, & too vulnerable/costly to use in the A2G role,

( as were the A-20/A-24/A-26 in the ETO) & so then tried them as defacto medium bombers

( Mosquito style) instead, but they weren't too effective in this, either.

 

The 9th AF P-47s suffered fairly heavily in their new tactical duties on ground support for the invasion forces,

losing nearly 1500 in combat between D-day & VE-day, both to flak & Luftwaffe anti-JaBo ops,

which proved more profitable for the Jagdwaffe, than vainly trying to battle the P-51s.

 

Ironically, the P-51's outright victory figures ( & victoty-to-loss ratios)  for both A2A, & A2G ops

- were better than the putatively 'rugged' P-47, let alone the pretty-much unwanted P-38.

 

Both 109/190 could lose the low Mach/high drag handicapped P-38 in a dive, as well as being able to contend effectively in A2A combat  with the fat-as P-47 below 15,000ft, (esp' when the 'Jug' was bomb-laden,

& even a forced ordnance jettison - was rated a 'success' for the hard-pressed LW fighters).

 

The P-38's low limiting dive-speed of ~440mph EAS was poor versus the single-engines fighters in the ETO,

(  ~100mph less - than some, such as the Tempest).

[Meplat]

15 minutes ago, M.B-5 said:

P-38 missed out on a bubble canopy upgrade, unlike the P-47, & P-51.

P-47D got an improved windshield & bubble canopy - which was pretty much a straight copy

- from the Hawker Typhoon.

 

When the 'Mighty 8th' cast-off its P-38 & P-47 units for the more effective P-51, the 9th 'tactical' AF got them,

for 'mud-moving' tasks, even though they were expensively optimised for high-altitude work with turbochargers,

& not at their best - down low. 

 

The 9th AF quickly found the P-38 to be too big, & too vulnerable/costly to use in the A2G role,

( as were the A-20/A-24/A-26 in the ETO) & so then tried them as defacto medium bombers

( Mosquito style) instead, but they weren't too effective in this, either.

 

The 9th AF P-47s suffered fairly heavily in their new tactical duties on ground support for the invasion forces,

losing nearly 1500 in combat between D-day & VE-day, both to flak & Luftwaffe anti-JaBo ops,

which proved more profitable for the Jagdwaffe, than vainly trying to battle the P-51s.

 

Ironically, the P-51's outright victory figures ( & victoty-to-loss ratios)  for both A2A, & A2G ops

- were better than the putatively 'rugged' P-47, let alone the pretty-much unwanted P-38.

 

Both 109/190 could lose the low Mach/high drag handicapped P-38 in a dive, as well as being able to contend effectively in A2A combat  with the fat-as P-47 below 15,000ft, (esp' when the 'Jug' was bomb-laden,

& even a forced ordnance jettison - was rated a 'success' for the hard-pressed LW fighters).

 

The P-38's low limiting dive-speed of ~440mph EAS was poor versus the single-engines fighters in the ETO,

(  ~100mph less - than some, such as the Tempest).

I'm waiting for you to explain how the P-38 could have benefited from a" bubble canopy"..

 

[M.B-5]

Have you sat in a P-38?

There are canopy frames which intrude on a clear view, & they're lateral-wise, right at eye-level,

annoyances which are notably absent from a proper,  blown 1-piece - bubble canopy.

[Meplat]

2 minutes ago, M.B-5 said:

Have you sat in a P-38?

There are canopy frames which intrude on a clear view, & they're lateral-wise, right at eye-level,

annoyances which are notably absent from a proper,  blown 1-piece - bubble canopy.

 

My grandad was a senior tech for Allison pre WW2, and spent the majority of WW2, working on P-38's, winning a bronze star for keeping them in the business of killing Nazis.. 

Prior to opening a business restoring WW2 armor, I worked on more than a few WW2 aircraft, being an A&P mechanic with more than a bit of hands on experience on WW2 era aircraft..

 

A blown/"Malcom Hood" would have contributed jack and/or shit to the performance/effectiveness of the P-38.

 

 

[Jeeps_Guns_Tanks]

21 hours ago, M.B-5 said:

Hi y'all.

 

Some interesting views put forth, here in this thread.

Do allow some corrections, though, won't you fellas...

 

1,The rear "Aux" fuselage tank in the P-51 wasn't actually a "drop tank" - it was for transit flying & was used 1st,

rather than in combat.

2, P-38 did ok against the lesser forces of Nippon, but could not technologically* hack the pace in the ETO,

  & was replaced by the P-51.

3, P-47, like the other P&W R-2800 powered fighters  - was a real gas-hog,  even at a slow cruise speed,

& like the P-38, was dumped by the 8th AF, on the advent of the P-51 - arriving in numbers.

4, P-51 did not need the "dive flaps" belatedly attached to both P-38 & P-47 to recover control,

& pull out safely - from 'Mach crit' high speed dives.

5, Victory stats collected by the USAAF in the ETO, confirmed their top choice of the P-51 as air-superiority fighter,

- was the right one**.

 

* P-38 was a real handful of control complexity to simply fly, let alone operate in combat - esp' against the faster diving 109/190, whose pilots could spot the big twin-boom Lockheed from a distance,

& then choose an attack profile - to suit themselves. 

 

**The RAF wanted all the Mustangs they could get, (even the Allison powered ones, which they used 'til war's end),

but didn't want P-38's, & relegated the hundreds of lend-lease P-47's they received - solely to combat against the lesser forces of Nippon, too. 

 

 

 

 

 

I have some objections to this post. 

 

1: You seem to have misread something in the thread here, I don't recall anyone claiming the rear fuselage tank was a drop tank, and I even posted a pic showing its capacity. 

2: The P-38 did just fine in every theater it fought in. It may not have done as well in the hands of the 8th, but there were other issues involved, that had more to do with the 8th Air Force's problems in how they handled the P-38, funny how their use Alaska and Iceland had few issues with cold weather operations and the P-38. To dismiss its success in the Pacific like the Japanese were vastly inferior to the Germans is a cop out, and German aircraft were not all that great, and neither were their pilots by 43/44.  The P-38 was never fazed out of the ETO, the 9th used them to the end, they were in demand in every theater and stayed in demand in every theater right to the end of the war, but the P-51 coming onto the scene dropped the demand a lot in Europe.  The P-38 was actually more technologically advanced than the P-51 as well. The turbo system was cutting edge. The P-51 did save the 8th Air Forces bacon, and for that, it gets all the glory, because the 8th got a lot of press.  By 1944, the US was producing the best-trained pilots in the world, period. 

 

3: Odd, I do not see anything I would call a VAST difference in fuel consumption at various setting in the R-2800 and Merlin.  Some sure, but nothing I would call vast. I would chalk up range differences mostly being fuel tank capacity of the plane. As the war progressed, the P-47 and P-38 also gained fuel tanks and late war P-47s would outrange the P-51.

4: The P-51 didn't get dive flaps, not because it couldn't get into compressibility, but because it took a little longer and pilots were trained to avoid diving with to much power. When it did get into compressibility it had a tendency to lose its tail when trying to pull out. Granted a weak tail was a known issue. The reason it was a big deal on the P-38 is that the P-38 was one of the first planes clean and heavy enough to run into it. The P-51 benefited from a lot of lessons the US Air Force learned because of the P-38. 

 

5: Yeah, sounds like they surveyed only P-51 and Bomber pilots in the 8th. Wooooopdy doo. A link to a source on this would be nice though. 

 

All WWII Aircraft had complex controls, at least on the US side of things, it wouldn't be until later P-47 models were they started toying with a lot of automatic controls. The P-38 was a tad worse, but the very well trained pilots coming out of the US training system could handle it fine since they tended to send the best performers into the P-38 pipeline, well at least the ones that went everywhere but the 8th Air Force. 

 

 

[Jeeps_Guns_Tanks]

51 minutes ago, M.B-5 said:

P-38 missed out on a bubble canopy upgrade, unlike the P-47, & P-51.

P-47D got an improved windshield & bubble canopy - which was pretty much a straight copy

- from the Hawker Typhoon.

 

When the 'Mighty 8th' cast-off its P-38 & P-47 units for the more effective P-51, the 9th 'tactical' AF got them,

for 'mud-moving' tasks, even though they were expensively optimised for high-altitude work with turbochargers,

& not at their best - down low. 

 

The 9th AF quickly found the P-38 to be too big, & too vulnerable/costly to use in the A2G role,

( as were the A-20/A-24/A-26 in the ETO) & so then tried them as defacto medium bombers

( Mosquito style) instead, but they weren't too effective in this, either.

 

The 9th AF P-47s suffered fairly heavily in their new tactical duties on ground support for the invasion forces,

losing nearly 1500 in combat between D-day & VE-day, both to flak & Luftwaffe anti-JaBo ops,

which proved more profitable for the Jagdwaffe, than vainly trying to battle the P-51s.

 

Ironically, the P-51's outright victory figures ( & victoty-to-loss ratios)  for both A2A, & A2G ops

- were better than the putatively 'rugged' P-47, let alone the pretty-much unwanted P-38.

 

Both 109/190 could lose the low Mach/high drag handicapped P-38 in a dive, as well as being able to contend effectively in A2A combat  with the fat-as P-47 below 15,000ft, (esp' when the 'Jug' was bomb-laden,

& even a forced ordnance jettison - was rated a 'success' for the hard-pressed LW fighters).

 

The P-38's low limiting dive-speed of ~440mph EAS was poor versus the single-engines fighters in the ETO,

(  ~100mph less - than some, such as the Tempest).

3

 

The P-38 didn't need a bubble, and if anyone had proposed one, it wouldn't have made it into production, because the P-38 was considered too important to slow the production down for a minor thing no one complained about. 

 

The mighty 8th was mighty good with the press, but are hardly a shining example of a great Air Force. Go read about the things the 5th did. 

 

The 9th used the P-47 and P-38 right to the end of the war, so what's your point?

 

On the 9ths P-47s stats, do you have links or references, cause that sounds interesting, but well you know...

 

By the point in the war, we are talking about most German pilots could barely fly, so talking about how they could, if they really knew their shit, outperform a P-38 or any other allied fighter by flying their German shitbird to the limits is pretty silly if you ask me. 

 

 

[Jeeps_Guns_Tanks]

37 minutes ago, M.B-5 said:

Have you sat in a P-38?

There are canopy frames which intrude on a clear view, & they're lateral-wise, right at eye-level,

annoyances which are notably absent from a proper,  blown 1-piece - bubble canopy.

 

 

Were you in a neck brace when you sat in a P-38? You know you can move your head around right? The general complaint by P-38 pilots about visibility was they couldn't see below it will cause the engines got in the way. 

[Meplat]

Just now, Jeeps_Guns_Tanks said:

 

 

Were you in a neck brace when you sat in a P-38? You know you can move your head around right? The general complaint by P-38 pilots about visibility was they couldn't see below it will cause the engines got in the way. 

In truth, I was... Just got out of a plane crash...

 

But yeah..

 

[Meplat]

Shit, like it or not, most of the P-38 info in wart-chunder I provided.

last I heard, my name was still in the credits, even if I can't post int he forums.

[Jeeps_Guns_Tanks]

4 hours ago, Collimatrix said:

Hello M.B-5, and welcome to SH!

I am not well-versed in the specifics myself, but I would suspect that plenty of P-38 fans would come forth to defend its honor, even in spite of its shortcomings in the European theater.  Among other things, a lot of the P-38s in combat early on in Europe were the downgraded export models which lacked handed propellers, and, at least according to some sources, received inferior maintenance to P-38s in the Pacific Theater.  P-38 was a very maintenance-intensive bird, and it would not give its best performance if not looked after very carefully.

There were other problems too, like improperly mixed fuel.  The Americans were far, far ahead of other nations in av-gas formulation in WWII, and some of the fuel used in the ETO didn't have the anti-knock agents mixed correctly.  Bottom line was that the V1710s in a combat wing of P-38s were very likely not performing how they would on a test stand in the Indianapolis factory.

By the time the P-51 showed up, these problems were a lot better understood, so in large part the P-51 benefited from a lot of experience gained on earlier models of fighter.

I'm a little curious to know why exactly a Bf 109 could out-dive a P-38.  According to the parasite drag and thrust chart posted before, the P-38 had a very low drag coefficient despite being twin engine.  Might have had something to do with the fairly low Mcrit.

I have been unable to find good specific fuel consumption charts for the most common WWII piston engines, but my book on Allied piston engines claims that the R2800 was in the middle of the pack for efficiency.  True, it did guzzle fuel, but it produced a ridiculous amount of energy while doing so.  The lower fuel consumption of the P-51 vs the P-47 is, I would think, less a function of the Merlin being a more efficient engine than the R2800 and more a function of the Merlin being a much smaller engine than the R2800.

Sleeve valve engines generally had higher compression ratios, so I would expect them to have a modest advantage in specific fuel consumption compared to conventional poppet-valve engines.

 

 

Nah, the dumbass Brits ordered their P-38s with non-contra rotating props and no turboes because they wanted commonality with the early P-40s. Lockheed warned them how bad that would be, but Brits being Brits, they did their thing, then canceled the order at like 8 planes when they realized how dumb their decision was.   No combat P-38s had non-contrarotating props. 

 

The clearest reason for the 8th Air Forces P-38 problems were morale and competence related to the guys maintaining the planes right up to the Generals. 

 

See my post a few back for fuel consumption charts

 

[Meplat]

1 minute ago, Jeeps_Guns_Tanks said:

 

 

Nah, the dumbass Brits ordered their P-38s with non-contra rotating props and no turboes because they wanted commonality with the early P-40s. Lockheed warned them how bad that would be, but Brits being Brits, they did their thing, then canceled the order at like 8 planes when they realized how dumb their decision was.   No Combat P-38s had non-contrarotating props. 

 

The clearest reason for the 8th Air Forces P-38 problems were morale and competence related to the guys maintaining the planes right up to the Generals. 

 

See my post a few back for fuel consumption charts

 

Yeah, grandad did have some less than kind words about some "mechanics".

By the time he was a CWO4, I'm sure he saw all kinds of ass-hattery.

When he had me working on his Navion in JHS, it was brutal. 

But looking back, it was worth it.  "Be meticilous in your work" .

 

Also- "sleeve valve mills love to fucking eat oil" .

[Jeeps_Guns_Tanks]

Oh Hey @Collimatrix

 

The early F4U-1 models had fuel tanks in the outer wing panels, these were dropped by the -1D model, they were not popular and like the main tank had a tendency to leak. 

 

The P-38 gained wing tanks when the moved the intercoolers from the leading edge of the wing, they used the space for a 55-gallon tank in each.  The early wing leading edge intercooler was a big part of the early P-38s issues. 

[Meplat]

8 minutes ago, Jeeps_Guns_Tanks said:

Oh Hey @Collimatrix

 

The early F4U-1 models had fuel tanks in the outer wing panels, these were dropped by the -1D model, they were not popular and like the main tank had a tendency to leak. 

 

The P-38 gained wing tanks when the moved the intercoolers from the leading edge of the wing, they used the space for a 61-gallon tank in each.  The early wing leading edge intercooler was a big part of the early P-38s issues. 

They always had issues with the prestone tanks as well.  That shit would seep through the smallest crack. (it still does)

One of my grandad's anecdotes was of a pilot who claimed his P38 was "the tits", but it always came back with scary low prestone.

 

Turned out that at manually applied high boost, it was leaking (spraying) prestone into the intake after the pressure carb, and providing a skosh of ADI.

Once it was fixed, "it never ran the same".

[Collimatrix]

2 hours ago, M.B-5 said:

 

Both 109/190 could lose the low Mach/high drag handicapped P-38 in a dive, as well as being able to contend effectively in A2A combat  with the fat-as P-47 below 15,000ft, (esp' when the 'Jug' was bomb-laden,

& even a forced ordnance jettison - was rated a 'success' for the hard-pressed LW fighters).

 

The P-38's low limiting dive-speed of ~440mph EAS was poor versus the single-engines fighters in the ETO,

(  ~100mph less - than some, such as the Tempest).

 

 

Whoah whoah whoah.

The critical mach number problem was mainly an issue of sonic shock waves forming over the wings of the aircraft.  All wings will do this if the airflow over them gets fast enough, the problem was just that most airfoils designed in the 1930s would form shock waves at fairly low mach numbers.  The reason that the Tempest out-dives a Lightning is that it has laminar flow wings, not that it has a single engine.  Laminar flow wings have a higher critical mach number than the traditional airfoil designs that were used in the late 1930s.

Very few Axis fighters had laminar flow wings, the J2M Raiden being the only one I can think of offhand.  The Bf 109, being a mid 1930s legacy design definitely started with traditional airfoils, and I can find no reference to the Bf 109 having ever been re-designed to have laminar flow wings.  Likewise, the FW-190 seems to have lacked laminar flow wings as well.  So the Bf 109 and FW-190 would also have problems with their critical mach numbers while diving, and most likely at around the same airspeeds as the P-38.  If their airfoils were slightly less cambered or had a slightly higher chord to thickness ratio then M_crit may have been somewhat higher, but it would have been a small difference of degree rather than kind.

[M.B-5]

On ‎15‎/‎11‎/‎2017 at 1:14 AM, Jeeps_Guns_Tanks said:

Don't forget the wonderful for making the plane handle poorly so it was drained before the drop tanks behind the pilot fuel tank in the P-51D.

 

"...drop tanks behind the pilot..."

 

Yeah, sorry to be a grammar Nazi, J_G_T, but that's a real lousy sentence.

 

& sleeve-valve engine oil-consumption was certainly better than the big US radials, with their loose clearances

plus a multitude - of leaky joints...

 

The P-51 was not only much more fuel efficient/aero-slick than the R-2800 powered gas-hogs,

_ its cruise speed was ~ 100mph faster.

 

Funny that both the P-51 & P-47 were deemed worthy of significant revision (despite being in high demand),

but the P-38 wasn't, - due to the Lockheed being fairly close to being past its 'best by date' - by USAAF appraisal/reckoning.

 

& the German forces were a far more effective/dangerous enemy than those of Hirohito,

just as the USAAF losses lists - clearly show.

 

[M.B-5]

1 hour ago, Collimatrix said:

 

 

Whoah whoah whoah.

The critical mach number problem was mainly an issue of sonic shock waves forming over the wings of the aircraft.  All wings will do this if the airflow over them gets fast enough, the problem was just that most airfoils designed in the 1930s would form shock waves at fairly low mach numbers.  The reason that the Tempest out-dives a Lightning is that it has laminar flow wings, not that it has a single engine.  Laminar flow wings have a higher critical mach number than the traditional airfoil designs that were used in the late 1930s.

Very few Axis fighters had laminar flow wings, the J2M Raiden being the only one I can think of offhand.  The Bf 109, being a mid 1930s legacy design definitely started with traditional airfoils, and I can find no reference to the Bf 109 having ever been re-designed to have laminar flow wings.  Likewise, the FW-190 seems to have lacked laminar flow wings as well.  So the Bf 109 and FW-190 would also have problems with their critical mach numbers while diving, and most likely at around the same airspeeds as the P-38.  If their airfoils were slightly less cambered or had a slightly higher chord to thickness ratio then M_crit may have been somewhat higher, but it would have been a small difference of degree rather than kind.

 

No, the 109/190 readily exceeded the P-38's Vne in the dive, & like the P-51, didn't need 'dive flaps' to regain control.

 

The thick-winged Typhoon was still cleared to dive at a 525mph EAS limit, though the Tempest's 'high speed wing ' profile allowed a later onset of drag/extra control capability & gave another ~25mph advantage - across the flight regime , by comparison.

 

P-38 'buffet' - bad enough to cause structural damage - was noted by the USAAF as a fundamental problem.

 

The Tempest was very robust though, with an ultimate stress rating of 14G, rather more than the USAAF design max.

 

See: period drag/structure documents; http://www.ww2aircraft.net/forum/threads/structure-weight-data-and-drag-analysis.42716

 

[Sturgeon]

More primary sources, less contesting the sentence structure of established members' posts.