No P-51 Mustang

[zoomar]

Let's imagine that in 1940 the British Purchasing Commisison that was negotiating an order with North American Aviation for mass production of P-40s for the RAF rejected NA's offer to design and provide a production prototype of their own plane - a design that became the P-51 - and instead insisted on the P-40s.

How might that affect the mix of allied aircraft in the ETO and PTO and the broader course of the air war? Would the USAAF be satisfied with the P-47 and P-38 combo that was their original intent, or would other designs be sought? If so, which ones? How might that affect the later development of North American as a major producer of their own fighter designs such as the F-86 and F-100?

 

[Just Leo]

Things that happen by accident or serendipity often surpass the abilities of things that were planned. The P-75 was planned.

 

[MattII]

How would a Merlin engined P-40 have performed do you think?

 

[tchizek]

How would a Merlin engined P-40 have performed do you think?

They tested several P-40 airframes and it had basically the same performance as a P-40N.

 

[zoomar]

Things that happen by accident or serendipity often surpass the abilities of things that were planned. The P-75 was planned.

That's what happens when you ask General Motors to design a fighter. Imagine the joy of the Luftwaffe finding these in the skies over Europe instead of Mustangs!

 

[MattII]

They tested several P-40 airframes and it had basically the same performance as a P-40N.

Better high altitude performance though, surely. I mean that's why the P-51 ended up with the Merlin, because the Allison couldn't hack it above 15,000 feet.

 

[Peg Leg Pom]

Things that happen by accident or serendipity often surpass the abilities of things that were planned. The P-75 was planned.

I don't know what the designers of that contraption had been drinking, but where can I get some?

 

[Just Leo]

Somebody hasn't been doing enough googling. The Merlin-powered P-40F was a standard model. That's why the Packard company started making Merlins in the first place. Easily identified by the lack of carb air intake atop the cowl, the P-40F had slightly improved altitude performance but it's lack of aerodynamic finesse precluded the transformation that happened with the Mustang.

The P-75 Eagle was designed by GM engineers led by Donovan Berlin, ex-Curtiss designer of the P-40. He left Curtiss in a huff about poor corporate decisions. Neither Berlin nor Curtiss benefitted from the split.

 

[zoomar]

Glad you cleared the Merlin thing up, Leo. The P-40's problem really was less about its engine than its airframe.

I didn't know about the P-75 being designed by team under an ex Curtiss designer, but that just maybe proves the old joke about Texans and Oklahomans: if you move from one state to the other you lower the IQ of both.

Curtiss certainly couldn't come up with a creditable fighter after the P-40 no matter how many design/production contacts they got, and GM should never have even been offered the chance.

Case in point. Can't you just see this making the Luftwaffe shake in their boots?

 

[tchizek]

Better high altitude performance though, surely. I mean that's why the P-51 ended up with the Merlin, because the Allison couldn't hack it above 15,000 feet.

Nope the P-40N had fine performance up to about 25K. Which was about where the Merlin started running out of power as well, they both had mechanical superchargers.

The P-51 got the Merlin because Packard could produce them and the Allison production was already over-allocated. The Allison was fine with a turbo up to 30K+ and 25K with a supercharger. Which was true of all piston engines, the Merlin worked in the P-51 above 15K because it had a two stage, two speed supercharger. Without that the Merlin ran out of power at ~7-9K.

 

[bsmart111]

Remember the Mustang that North American initially sold the British on was Allison powered. I think if the BPC had not accepted the North American proposal North American would have continued working on the design. Everyone knew the P-40 wasn't the long term solution. With the breathing room of having more than 120 days to do the prototype they may have thought of the Merlin for the first production planes.

 

[Sior]

Would Britain then gone for the Martain Baker 5 as their long range escort fighter?

 

[Just Leo]

The North American design team consisted of some pretty sharp design engineers. I'm a bit of a fan of Edgar Schmued myself. (What if his parents hadn't emigrated from Germany? Would there be a German Mustang?) The genesis of the Mustang occurred during a confluence of new ideas in aerodynamics. In AH, it's common to "push things forward 3 years because of increased priority" but the Mustang arose when factors were just right for it to happen, and the 60 series Merlin was brand new. The NACA "laminar flow" airfoil had just hatched, resulting in a voluminous location for the fuel tanks. The Spitfire rad used Meredith effect, but the Mustang rad was pure Meredith, benefitting from both the effect, and the location.

What would have happened with no Mustang? Something else would have happened. Maybe CalBear's Corsairs could fill the void, but they were expensive too, compared to the Grumman. Maybe the P-47N would have received the AH push and been developed sooner. Maybe the Lightning would have been multiple sourced sooner. Other aircraft could have done the job, but the Mustang was cheap, easy, and good at the right time. It would have made the war more expensive. Maybe if they stopped supplying GIs with chewing gum, they could make up the difference. But then, Wrigley Field would become derlict, and Chuck Yeager wouldn't break the sound barrier.

 

[tchizek]

Glad you cleared the Merlin thing up, Leo. The P-40's problem really was less about its engine than its airframe.

Absolutely, that was the point I was trying to make - but badly. Thanks Leo for finishing making it! The P-51 airframe was amazing!

I didn't know about the P-75 being designed by team under an ex Curtiss designer, but that just maybe proves the old joke about Texans and Oklahomans: if you move from one state to the other you lower the IQ of both.

Curtiss certainly couldn't come up with a creditable fighter after the P-40 no matter how many design/production contacts they got, and GM should never have even been offered the chance.

Well Donovan Berlin left the company in mid 1940 and joined up with Northrup(I think?). Curtiss was never able to replace him, so they were rehashing old designs and attempting to make due with less experienced designers.

Case in point. Can't you just see this making the Luftwaffe shake in their boots?

If it can fly it might make them laugh so hard they can't fly...

 

[Just Leo]

Would Britain then gone for the Martain Baker 5 as their long range escort?

James Martin got the idea for the rad from somewhere that didn't exist anymore. The MB-5 would have had the same Me-109-style rads as the MB-3, resulting in the same lack of internal fuel storage volume that plagued the 109. The Tempest, Fury and Hornet would not have had the evidence of Laminar flow performance advantage waved in their face. Other designs tried the airfoil and it didn't work. The Mustang showed it did work.

 

[voss749]

More likely than not they would have just stuck with the proven P-47, and figure out ways to enlarge the fuel tank and extend its range.

 

[Andras]

P-38s with combat flaps could hold their own against single engine planes.

P-47s could have been fitted with long range wings (N model), but the D model with long range external tanks could go 1700miles

Corsairs w 300gallons external fuel could make it to Berlin and back.

The P-75 used Mustang wings so that may use something else and still be a failure.

The US wouldn't export P-38s w/turbochargers, so maybe the Brits fit Merlins to their P-38 instead. The Xp-49 was a P-38 designed to take the 24cylinder 2000hp X-1800, which never came about. Maybe the Brits order it with Napier Sabres (473mph)

The advantage the Merlin had in 1942 was a two stage- two speed supercharger. The USAAC wanted it's high altitude fighters to use turbochargers and actively dissuaded the engine manufacturers from developing better superchargers. Of course, it then blocked the turbochargers from export.

 

[CalBear]

Glad you cleared the Merlin thing up, Leo. The P-40's problem really was less about its engine than its airframe.

I didn't know about the P-75 being designed by team under an ex Curtiss designer, but that just maybe proves the old joke about Texans and Oklahomans: if you move from one state to the other you lower the IQ of both.

Curtiss certainly couldn't come up with a creditable fighter after the P-40 no matter how many design/production contacts they got, and GM should never have even been offered the chance.

Case in point. Can't you just see this making the Luftwaffe shake in their boots?

If had managed to hit designed speeds (and with a 2,300 HP engine and contra-rotating props, it was a good candidate for that speed) they would have found it ugly and scary as all hell.

450MPH is nothing to sneeze at, nor were the 4 20mm cannon it was designed to carry.

 

[CalBear]

Things that happen by accident or serendipity often surpass the abilities of things that were planned. The P-75 was planned.

In the P-75's defense it was meant to be built from the parts bins of several other aircraft, including the Mustang (later the P-40), Corsair, SBD, and other planes.

It was designed to have 400 miles more range than the P-51 and it carried TEN .50 Cal MG.

If you think the result as it came out was... odd, consider this: The original design also called for it to have the same sort of inverted gull wing as the Corsair.

 

[Just Leo]

It turned out surprisingly well considering it started with a Dauntless tail Corsair maingear, P-40 outer wing panels, Airacobra engine layout, Mustang rad layout, and a Buick cockpit canopy.