WI: Effects of an earlier development of P-51 on Allied air campaigns?

Just Stuffing a Merlin XX or 61 in a Mustang one only gives you a test aircraft. the RR Merlin was heavier than the Allison and IIRC the wings had to be moved forward several inches to get the aircrafts CoG back to within limits that gave a performance and handing suitable for combat.

Merlin XX weighted about the same as the V-1710 + two HMGs installed under it - basically no change in weight distribution. Unfortunately, there was no such thing as Merin XX/V-1650-1 on the Mustang fuselage, let alone many hundreds of them like it was the case with P-40F/L.
P-51B introduced fuselage deeper by 7 in, longitudinal position of wing remained the same. Heavier engine was counterbalanced by heavier radiator system, that now included a radiator that served the intercooler (similar 'trick' was used on Spitfires and Bf-109s), as well as with introduction of the fuselage tank by the P-51B-5. Mustang X featured intercooler under the chin, it was still working fine.

It is really too bad that powers that were didn't insisted in turning the Mustang X project (5 total modified from Mustang I) into a pattern for actual combat aircraft, that should amount to many hundreds by May/June 1943.
 
Even one squadron with 1945 Allied pilots would probably be sufficient to remove all the Stukas and therefore prevent the crossing?

To be fair, you can same the same with Hurricane, Spitfire, Hawk or D.520. If you have an equivalent to the UK's air defence system running in France then any half decent fighter is going to slaughter Stukas (as happened several times during the Battle of Britain). The biggest problem the Allied air forces had in 1940 (other than some French commanders really preferring not to have their fighters take off) is that they're forced to waste huge amounts of time patrolling then reacting to German moves at a disadvantage whereas in the Battle of Britain the RAF could do without standing patrols that exhausted pilots, wasted hours on the aircraft and left them vulnerable to being jumped by the Luftwaffe. By the time the Mustang was in its pomp over Germany, of course, the Germans had a number of disadvantages that meant they could never exploit their radar systems anywhere near as well as the RAF could. A proper air defence system would also prevent the attacks on airfields being able to take so many aircraft out on the ground.

Improving the French air defence system means you can concentrate fighters against raids rather than having to spread your fighters all over the frontiers on patrols. The Mustang has an advantage over the Bf.109Es compared to the early war fighters but any of them are so superior to the Stukas that if they can get at them in numbers it'll be a slaughter.
 
I have Skippy the Alien Space Bat on the speed dial just for these occasions :)
(Indiscriminate chirping)

"What's that Skippy? There's some upengined P51Ds stuck down the well?"

(Slightly disturbing subsonic cawing)

"And there's a little plane in danger who's plumb tuckered out?"

(Several eeks and a caw)

"Strewth Skippy! Fly to her with your leathery wings!!!"

(The sky darkens as a webbed forearm stretches across the horizon)

"Floi to her Skippy! Floi!"

(The screen changes to the "to be continued" card. The credits roll as the theme tune strikes up)

"Skippy, Skippy, the bush alien space bat! Skippy, Skippy..."
 
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This conversation makes me wonder just how well would US airframes have done with Hispano Suiza 12Z engines if France held. Ford was apparently far more interested in producing this in the US than the Merlin, and the Swiss wanted to cooperate on its development too. The Swiss did quite a nice job with the Saurer YS-2 and 3 based on the HS-12Y (or early Z).
 
This conversation makes me wonder just how well would US airframes have done with Hispano Suiza 12Z engines if France held. Ford was apparently far more interested in producing this in the US than the Merlin, and the Swiss wanted to cooperate on its development too. The Swiss did quite a nice job with the Saurer YS-2 and 3 based on the HS-12Y (or early Z).

If Ford was really more interested in producing the HS 12Z than the Merlin in the USA, it was a huge mistake on their part.
Both 12Z and Saurer's engines were all-new engines vs. 12Y. By 1945, the benchmark for V12 engines was 2000 HP, neither of those came close (1800 HP figure for the 12Z - any - is bogus). Unlike Merlin, there was no 2-stage supercharger on either of those, even if we look at post-war developments.
 

CalBear

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And even if the USA considered the P-40 inadequate the P-38 Lightning was in development and the P-39 Airacobra for that matter.
Imagine a P-39 with a Packard 1650 in 1939. Be death on flippin' stick from sea level to 35K (its more or less a P-63, which was itself a vastly underrated aircraft). The Airacobra was more maneuverable than anything in the sky in 1939, it just ran out of power at 17K, which was where the action started in the ETO and the Allison engine model in the P-39 was absolute shite in high humidity, making it pretty much worthless in the South Pacific.

Still have to get rid of the GD Car Door entry into the cockpit.
 

As it says on the tin.

What would be the effects on the Allied air campaigns in WWII if there was an earlier development of North American's P-51 Series, basically the aircraft being developed around the early 1930's, the same time as the Hurricane, Spitfire and Bf 109?

What would be the effects of these aircraft being in service from 1939?
What effect would it have on the Luftwaffe or even the Japanese?
How would the BoB or even Battle of France play out if either were used by the RAF or the French?
Would they be used as part of 'Lend-Lease' to the USSR?

Much obliged!
R9a0f28215ac6925476a1a89593215251

P-51 Mustang and Derivates Ideas and Inspiration

There are more than one set of ways to skin a BF-109. The FW-190 started as a radial-engined fighter. The Apache can be hog-nosed the same way.

Also, some things need to be kept in context.

Notice the role of the P-47 THUNDERBOLT?
 
Imagine a P-39 with a Packard 1650 in 1939. Be death on flippin' stick from sea level to 35K (its more or less a P-63, which was itself a vastly underrated aircraft). The Airacobra was more maneuverable than anything in the sky in 1939, it just ran out of power at 17K, which was where the action started in the ETO and the Allison engine model in the P-39 was absolute shite in high humidity, making it pretty much worthless in the South Pacific.

Still have to get rid of the GD Car Door entry into the cockpit.
So basically a lot more plausible that the US turns to an existing airframe with a lot of wasted potential rather jumping to a design like the P-51 born out of a very particular set of circumstances? Wonder what it would take to make the US decide they needed to upgrade the P-39 in 1939?
 
So basically a lot more plausible that the US turns to an existing airframe with a lot of wasted potential rather jumping to a design like the P-51 born out of a very particular set of circumstances? Wonder what it would take to make the US decide they needed to upgrade the P-39 in 1939?
Should have been France 1940.

One technical comment. The P-39 is a small bird with severely limited range. If you are an American in 1940, you better be fixing that P-38 in a BIG WAY because your expeditionary forces will have to have a fighter with a combat radius of no less than 1,000 km.
From the Aviastar citation (^^^) (Work not mine.)
Specification
CREW1
ENGINE1 x Allison V-1710-85, 880kW
WEIGHTS
Take-off weight3765 kg8300 lb
Empty weight2560 kg5644 lb
DIMENSIONS
Wingspan10.4 m34 ft 1 in
Length9.2 m30 ft 2 in
Height3.8 m12 ft 6 in
Wing area19.8 m2213.13 sq ft
PERFORMANCE
Max. speed620 km/h385 mph
Ceiling10670 m35000 ft
Range1200 km746 miles
ARMAMENT1 x 37mm machine-guns, 4 x 12.7mm machine-guns, 1 x 226kg bomb


3-View
Bell P-39 Airacobra
A three-view drawing (1650 x 1183)
 
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CalBear

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So basically a lot more plausible that the US turns to an existing airframe with a lot of wasted potential rather jumping to a design like the P-51 born out of a very particular set of circumstances? Wonder what it would take to make the US decide they needed to upgrade the P-39 in 1939?
Wide access to a better high altitude engine, the AAF knew the P-39 had "issues" but thanks to some really poor decision making regarding turbo/supercharger designs in USAAF standards the Allision simply wasn't up to the task of addressing them (hence the mention of the P-63, which had an Allision with proper supercharging).

Do the same thing with the P-40 and you wind up with the P-40F with 1,500 miles of range carrying a REALLY big belly tank (141 gallons, P-51 would carry two 110 gallon tanks, but the 110 gallon tanks hadn't be brought into service in 1939 and the P-40 didn't have "wet" hard points on the wings at that time). The P-40 was, of course, a design that had pretty much hit the wall as far as bettering top end performance, even the much later "N" model tapped out a 378mph at high altitude. That said, in 1939, it would have been an almighty handful at any altitude against any opponent in the sky, as fast a Spitfire IIa and far more heavily armed.

The downside is that a way better P-39/P-40 might delay the P-51, and the Mustang was a spectacular fighter, definitely in the argument about best prop fighter of all time.
 
Imagine a P-39 with a Packard 1650 in 1939. Be death on flippin' stick from sea level to 35K (its more or less a P-63, which was itself a vastly underrated aircraft). The Airacobra was more maneuverable than anything in the sky in 1939, it just ran out of power at 17K, which was where the action started in the ETO and the Allison engine model in the P-39 was absolute shite in high humidity, making it pretty much worthless in the South Pacific.

Still have to get rid of the GD Car Door entry into the cockpit.

Car door was probably the least of concern in everyday use of P-39 in American or British hands. Real problems were pitiful range/radius (no wonder, 120 gals of internal fuel on -D and on and meagre drop tank of mostly 52 or 75 is useless in Asia/Pacific, and barely useful in ETO and MTO) and lack of power at altitude of the V-1710 of 1941-42 vintage. In any climate the air was was fought.
At 18000 ft, the V-1710s with 1-stage S/C (= on P-40s, P-39s, Mustangs if RAF is in question) in 1941-42 were delivering 900 HP, vs. Merlin 45 and XX making 1150 HP, the 2-stage supercharged R-1830-76 was making ~1050 HP. Even the Zero's engine of second half of 1942 was doing 950 HP at 18000 ft.
Airacobra had every reason to be very maneuverable in 1939 - it carried no guns, protection or radios
P-63 was of no use for the AAF for similar reasons - 136 gals of internal fuel is about half of what P-51B-5 to -K had. The 390-400 mph speed figure was 30-40 mph under what the trio of AAF premier fighters were doing by winter of 1943/44.
 
Wide access to a better high altitude engine, the AAF knew the P-39 had "issues" but thanks to some really poor decision making regarding turbo/supercharger designs in USAAF standards the Allision simply wasn't up to the task of addressing them (hence the mention of the P-63, which had an Allision with proper supercharging).

Do the same thing with the P-40 and you wind up with the P-40F with 1,500 miles of range carrying a REALLY big belly tank (141 gallons, P-51 would carry two 110 gallon tanks, but the 110 gallon tanks hadn't be brought into service in 1939 and the P-40 didn't have "wet" hard points on the wings at that time). The P-40 was, of course, a design that had pretty much hit the wall as far as bettering top end performance, even the much later "N" model tapped out a 378mph at high altitude. That said, in 1939, it would have been an almighty handful at any altitude against any opponent in the sky, as fast a Spitfire IIa and far more heavily armed.

The downside is that a way better P-39/P-40 might delay the P-51, and the Mustang was a spectacular fighter, definitely in the argument about best prop fighter of all time.

Allison had nothing to do with how the turbocharger & cooling installation was executed on the XP-39 (or on the XP-38 for that matter), that was Bell's (mis)conception - we can recall that P-47s excellent turbocharger installation was Republic's brainchild, not P&W's. Drag was horrible on the XP-39 (it have had the drag coefficient of a biplane and was immediately shipped to NACA for a clean up), intercoolers were not controlable ( = easy to over-cool or under-cool the compressed air).
The early, lighter P-40 with a V-1650-1 would've indeed been a fine fighter.
Last of the P-40s, the XP-40Q-2, was good for 420+ mph with a 2-stage supercharged V-1710 in Spring of 1944, ie. about as good as Fw 190D.
 
Allied deployment of a P-51 would increase Axis fighter pilot attrition, something they couldn't afford
It would also reduce Allied bomber attrition that would not be good for the Axis
The Axis power to suffer most from this would be Germany
The luftwaffe was already spread thin, they would have to pull back more units from the Eastern Front , not a good thing
 
Ignoring the technicalities and assuming ASB: Almost no strategic effect (probably).

The P51 was a great escort fighter due to its range, it wasn't systematically better than its peers in other dimensions, so I'm going to look at the effects of longer range but equivalent performance fighters in other periods with no overall increase in fighter numbers.
1940: I don't see it having much effect since the Allies were operating on the defensive. It is possible that it might have been used as an escort in the daylight raids in 1939/early 1940, but while this might reduce bomber losses it would raise allied fighter loses, both with very minor effects
1941: RAF fighter operations over France are at less of a disadvantage, but the German defenders retain the initiative and it doesn't have much effect. A radical (and unlikely) change would be to shift bomber command to daylight raids escorted in force by fighters. This would impose heavier losses on the German fighter force by attacking targets they want to defend, forces the Germans to withdraw fighters from other fronts. However, the British are unlikely to commit sufficient fighters to this campaign to inflict real damage on the luftwaffe. This is because the British wanted to preserve fighter command in case of Russia being defeated and the Luftwaffe returning to the West, so in this case fighter command losses might be similar and German losses higher than actual but bomb damage inflicted is likely to be similar (ie trivial).
1942: similar to 1941, the fighter command just does not have the strength to defeat the Luftwaffe, although it can impose heavier losses and force units to be withdrawn from other fronts.
So up to this point German losses are a bit higher but Germany has a better daylight air defence system and has probably produced more fighters and fewer bombers than in OTL. The net effect of a little less air support in the Med or on the Eastern Front is probably small.
1943: Fighters are available to properly escort the US 8th air force from the start, but this is where my assumption of no extra fighters starts to really limit the impact. As in the earlier years there are unlikely to be sufficient fighters to impose crippling losses on the Luftwaffe until Autumn/Winter and at this point the weather intervenes. It's important to understand that the Luftwaffe was suffering increasingly unsustainable losses throughout the 2nd half of 1943 The importance of the P51 here was psychological as much as anything. Being able to escort the bombers throughout their mission reduced their losses, raised their morale and gave strategists confidence in the plan. The relatively small number of P51s employed in escorting the bombers at the furthest extents of their journey saved some bombers and inflicted some losses but wasn't critical. They did allow the US to raid more distant targets than would otherwise have been the case but again this probably wasn't critical.

There are a few hypotheticals that I think are interesting
1. Salerno was chosen as the invasion beach in Italy because it was just within spitfire range (it turned out to be too far really). What if longer ranged fighters lead instead to a landing near Anzio? Given longer flight and shipping times this means less air support and a slower build up, so the landing is more likely to be defeated, but if successful it accelerates the Italian campaign by about 8 months.
2. What if Fighter command is fully committed to long range escorting of the 8th Air Force from the start of 1943? Fighter command might have been able to inflict similar luftwaffe losses to those the 8th air force inflicted in the spring of 1944 but a year early. US bombing is unlikely to inflict much more damage on German output than OTL, although if bomber command switches to daylight bombing this could change (but is unlikely). From 1944 the luftwaffe was still able to gradually build up a reserve to use on specific operations, but of decreasing quality, and this is likely to be the case with higher losses in 1943. The allies generally had significant air supremacy from the 2nd half of 1943, this change might bring this forward in time and make it greater in degree, but neither are likely to bring the war to an earlier end. Essentially airpower was critical for victory but was not sufficient.
3. DDay was in Normandy because it was within spitfire range, as with Salerno longer range fighters enable a wider range of invasion locations to be considered. However, given build up requirements and the coastline it's not obvious to me that there is a better alternative, although the Germans might have had to disperse their troops more widely
 
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