Could you have designed a better Warbird?

[Shortround6]

I've thought it was Allison/turbo combo that needed to be treated in a certain way, while turboed 1830 was void of such an issue?
Were the P-43 experiencing any issues with their powerplants?

The P-43 and early B-17s (Bs, Cs, and Ds for sure) had issues along with the early P-38s, different issues than the later ones but still issues. Add what works on a slow climbing, slow diving B-24 with a flight engineer to monitor the engines may not work on a fighter with rapid altitude changes and a busy pilot.
Early turbo controls measured the exhaust back pressure (pressure in the exhaust manifold) and tried to keep it at a value near an open exhaust near sea level. This pressure device opened/closed the waste gate to control the pressure and thus the speed of the turbine and thus the intake pressure to the carburetor. It was actually not very precise leading to rich or lean conditions and with the moisture in the exhaust it was prone to freezing in the sensor line, which could lead to runaway (exploding) turbines. Later turbo controls just measured the pressure coming out of the turbo compressor before the carburetor and offered better pressure control and less chance of freezing. These controls (at least the early ones) were part of the Army designed or specified turbo package and not really up to the airframe manufacturer. A lot of problems were caused over the years because certain items, like guns, radios, some instruments and even engines/propellers were "government furnished equipment" to the airframe manufacturer. The Government wrote separate contracts to the suppliers of those items and then supplied them to the airframe manufacturer who then installed them.
This lead to a lot of finger pointing when things went wrong.
One reason for R-R success was back in the thirties they established their own flight center to test engine installations and were able to make modifications and test them themselves rather than waiting for third parties to do the testing. With small contract before the US got in the war airframe manufactures could not afford to build, equip and test 'extra' aircraft over what the government ordered in order to catch problems the the Army or Navy weren't catching or rating high on the list of problems to take care of.

 

[tomo pauk]

Many thanks for the detailed info

 

[drgondog]

I have occasionally considered a deeper chord wing with reduced t/c (but same 'actual depth), same wingspan, with more taper to achieve a similar AR/Oswald efficiency.

Greater wing area, etc - for a P-51, would result in more possible fuel capacity eliminating most of the fuselage tank requirements. It would also result in lower lift loading making it more manueverable in turn and climb, and slow transonic drag rise due to the thinner wing.

Assuming the knowledge of today was available to re-think the P-51 wing, boundary layer control might be improved with no weight penalty - resulting in better drag and lift and improving pre-stall characteristics as well as theoretically raising the CLmax..

I would apply that to the P-51H concepts which lightened the airframe back to P-51B levels, which also improved yaw stability by extending fuselage 13 inches.

 

[tomo pauk]

Okay, lets continue with my what-if

FAA was also interested in having a fighter of great performance, since their Hurricanes, Martlets and Fulmars were lacking performance in late 1941. The new fighter in pipeline, was about to be flown just prior 1942, and the prototype was notably slower then both Spitfire Mk.VIII prototype and Mustang. Not just that, FAA was fearing that advent of new high performance Allied fighters would've spurred Axis forces to introduce even better planes for themselves, threatening FAA.
So they decided to go for each-way bet - to navalize Spit and to bolt the most powerful engine onto Firefly airframe.
The navalized Spit VIII offered better U/C layout than 'hooked Spitfire' FAA was experimenting so far, but it's wing (optimized for high speed) was regarded as a liability for a naval plane. The part of the wing outboard of hinges was of broader chord, resembling of a dog tooth (with tooth being at trail edge), so the wing area was increased 10%. The resulting Seafire III have had performance somewhere in between of RAF's Spit V and VIII, with an useful combat range. The 1st squadrons receive their planes early in 1943, and use it to a great success during invasions of Sicily Italy.
As for the Firefly, FAA was thinkering about Sabre even erlier, but now they decided to use it really. In order to avoid issues with engine, FAA chooses to go with 2100 HP - enough for 360 mph. The 1st squadrons receive their mounts in mid 1943, using them in early 1944.

 

[Rick65]

Not sure that I would have liked to be in a single Sabre engined naval aircraft even in 1944. The reliabilty of the Sabre was greatly improved by then, but still not so good that the Centaurus powered Tempest II didn't rapidly supersede the Sabre Tempest V post war.

 

[tomo pauk]

Perhaps Centaurus was chosen because it was perceived as more rugged, being air-cooled?
As for Sabre, toss some informations about reliability of it, for 1944.

 

[tomo pauk]

About the early German response, when encountering new Allied fighters:
The main adversaries Allied planes were facing in late 1942 were a good match for Spit VIII and Mustang, but Spit IX and Typhoon induced more worries for the Jagdwaffe. Luftwaffe also enjoyed (so far) better quality of pilots, but the numbers were not on their side. Therefore, they set to find the cure both in short- and long-terrm.
The short term solution was making DB 605 to run reliably at 1,42 ata, while BMW 801 are to receive MW system. Both systems were introduced in summer of 1943.
On long-term basis, Luftwaffe was to receive jet fighters. That approach have had few drawbacks, though. Jet engines were still at prototype stage, ditto for fighters that were to use them. Plus, it took two engines per fighter, if existing planes are to be produced only. So RLM demands a single-engined plane to be flown within half a year, and mass production to start before 1944. As a back-up, both 109 190 are to receive engines that would be 30% more powerful than existing ones, to be introduced early in 1944.
Unaware of all of that, Allied high commands decide to put pressure on Luftwaffe...

 

[tomo pauk]

...and that started on Aprils Fools Day, 1943.
USAAF mustered 150-odd P-47s and 100 P-38s, while RAF used 250 Mustangs, 200 Spits VIII and 300 Spits IX, plus 200 Typhoons; all equipped with drop tanks. As a bomber force, at disposal were 400 medium bombers and 150 B-17s. RAF will fly night bomber sorties vs. aircraft factories that were regarded as too dangerous for daylight force. The aim was to go 'beyond Ruhr', and all Luftwaffe-owned property was regarded as fair game.

At the end of the week, Luftwaffe in the west was only a pale shade of itself, despite relocating fighters from East and South.

 

[drgondog]

...and that started on Aprils Fools Day, 1943.
USAAF mustered 150-odd P-47s and 100 P-38s, while RAF used 250 Mustangs, 200 Spits VIII and 300 Spits IX, plus 200 Typhoons; all equipped with drop tanks. As a bomber force, at disposal were 400 medium bombers and 150 B-17s. RAF will fly night bomber sorties vs. aircraft factories that were regarded as too dangerous for daylight force. The aim was to go 'beyond Ruhr', and all Luftwaffe-owned property was regarded as fair game.

At the end of the week, Luftwaffe in the west was only a pale shade of itself, despite relocating fighters from East and South.

On April 1, 1943 only the 4th FG equipped with SpitV was operational. Neither the 56th nor the 78th FG were quite ready w/P-47C..55th FG P-38s didn't become operational until October 1943.

The first time the 8th AF FC could put up ~ 150 P-47s equipped to go to German border was after August, 1943 when the 353rd FG became operational and even then they weren't quite equipped to penetrate German airspace with enough fuel - and Spits were barely able to cross the Holland border.

On 1 April 1943 the entire 8th AF was only putting an average of 80+ B-17s (no B-24s yet). It wasn't until May that both B-24s and B-26 BGs became operational . The B-24s were assigned to Ploesti effort and did not return (significantly 'whittled down') until late August.

The B-26 in 3 CBW didn't put up a force exceeding 48 until August 19.

So, in mid-May 1943 was the threshold for the Entire 8th AF BC ability to put up 150+ B-17s, 12 B-26 (322BG) and ~ 40 B-24s. With 120 total effective P-47's...

Simply stated the LW was stronger than the 8th AF when considering the ability to fly west from Frankfurt through Hannover... and the only a/c capable of penetrating the German border in daylight was the 8th AF.. the 9th was just beginning to go operational.

 

[tomo pauk]

You're right all the way, Bill, but this is merely a what-if that starts with premise Merlins were on board P-51s from day 1, thus accelerating development of Spitfire Typhoon, and encouraging a more offensive attitude vs. Luftwaffe. I've started it with post #332 of this thread

 

[davebender]

You need about two years to put the Merlin into U.S. production. Meeting your timeline requires Packard to sign a license agreement with RR during 1939.

 

[tomo pauk]

Not really, Merlin was provided by RAF here, so Mustang prototype can go airborne in second half of 1940

 

[drgondog]

Not really, Merlin was provided by RAF here, so Mustang prototype can go airborne in second half of 1940

TP - If the merlin engine mounts, cooling system revisons to radiator core, etc were in the original design, and if the engines were available to be installed in US at NAA or upon arrival in UK, then it would have a shock to the LW on early and often fighter sweeps deep into Germany in early 1942

Had that happened you might also contemplate how the RAF might have invested in daylight bombing more with escort available. I also perceive a reduction in Spitfire and Hurricane production with licenses granted to England to start making the P-51 in the UK in 1941.

You could project that a reduction in Hurricane production would fill some of the potential merlin bottlenecks

 

[tomo pauk]

Hmm, Mustang produced by Blackburn Boulton Paul perhaps? Boy, Luftwaffe would've been given good run for their money Guess cancellation of Hurricane mass production (mid 1942?) would've make easier for Hawker to ramp up production of Typhoon too, while locating/curing the airframe issues earlier?
As for LR fighter sweeps, I'm all for usage of overwhelming power if possible, that's why I've contemplated spring of '43 as start of offensive. That way Mustang would've been backed by other designs from my posts, too.

 

[davebender]

Historical P51 production.
US Warplanes
618 Mustang Mk I. 1941.
150 P51. 1942.
500 A36 dive bombers. 1942.

Nothing like optimism!

U.S. production of the P-51 didn't shift into high gear until 1943. How many are you planning to build in England during 1941?

 

[drgondog]

Historical P51 production.
US Warplanes
618 Mustang Mk I. 1941.
150 P51. 1942.
500 A36 dive bombers. 1942.

Nothing like optimism!

U.S. production of the P-51 didn't shift into high gear until 1943. How many are you planning to build in England during 1941?

With a Merlin design profile for the XP-51 all of those could have been P-51B and production tooling in place in early 1942 in the UK.

The A-36 most likely would have been killed due to higher priority and the P-38 production probably would have been killed in late 1943 in the US with the P-51B replacing it.

 

[The Basket]

The reason NAA were given the contract was because the UK couldn't build enough aircraft.

And there was certainly no idea that the P-51 was any good.

It would have been the P-40 that the British would have produced in the early 1940s timeframe.

 

[drgondog]

The reason NAA were given the contract was because the UK couldn't build enough aircraft.

And there was certainly no idea that the P-51 was any good.

It would have been the P-40 that the British would have produced in the early 1940s timeframe.

The reason NAA was given the contract was that Curtis couldn't produce enough P-40s and NAA convinced the Brits that they could design and produce a Better fighter.

The point that TP was making is that a 'better aircraft' would have been the P-51B in 1940 instead of 1943 with no reason why not. The bottleneck was lack of USAAF support and a steady production allocation from Rolls until Packard could replace them.

As to British 'not being able to build enough aircraft' - it all depends on priorities doesn't it? Would the Brits rather build and deploy P-51B/Mustang III in 1941 or Hurricanes? - and I realize that switching aircraft in production and then deploying them is not so simple... BUT mechanics and logistics for the most crucial component was the engine and Hurricane crews would be maintaining the same engine.

 

[davebender]

I'll buy that. UK production of the Mustang starts during 1942 (with Merlin engine) and achieves large scale production during 1943.

Of course you also need to massively increase Merlin engine production. Historically Britain didn't produce enough for the Lancaster Bomber program. Building P51s in Britain makes the engine shortage even worse.

 

[tomo pauk]

Cancellation of Hurricanes solves that problem in mid/late 1942.