With the Typhoon, armour was increased, bomb rocket load was increased, eventually the limit reached in some cases was what the tyres could withstand on take off and landing with your average post D-Day metal mat runway. That isnt the first thing that springs to mind.
Engine choices for P-51 mustang ?
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Shortround6
Major General
The Typhoon was an 11,000lb airplane with four 20mm guns and clean wings.
Thinking you can take the engine out of it and drop the engine, propeller and cooling system into a 8500-9000lb plane in place of the existing engine, prop and cooling system is really going to require some structural reinforcement.
the Sabre engine makes the Griffon look small.
Our enthusiastic friend has not even figured out how to drop the 2500lb Sabre into the engine bay that used to hold an under 1400lb Allison engine, or how much lead he needs to balance the big propeller, or where he is going to put the radiator that has two weigh almost twice what the old radiator weighed (including coolant).
Here is a hint at what the problem involved. A P-51 at 8,000lbs was rated at a "G" limit of 8 G. If you increase the weight of clean plane to 9,850lbs you lower the G limit to 6.5 G's
Which means you can start bending the plane at 6.5 Gs and break the plane several Gs lower than what it took to break the plane when it weighed 8,000lbs.
Heck, the Typhoon needed different wheels, tires an brakes to taxi with a pair of 1000lb bombs than it did with a pair of 500lb bombs. But hey, we can increase the weight of the Mustang by 2000lbs (a ton) and not have to make any changes?
Thinking you can take the engine out of it and drop the engine, propeller and cooling system into a 8500-9000lb plane in place of the existing engine, prop and cooling system is really going to require some structural reinforcement.
the Sabre engine makes the Griffon look small.
Our enthusiastic friend has not even figured out how to drop the 2500lb Sabre into the engine bay that used to hold an under 1400lb Allison engine, or how much lead he needs to balance the big propeller, or where he is going to put the radiator that has two weigh almost twice what the old radiator weighed (including coolant).
Here is a hint at what the problem involved. A P-51 at 8,000lbs was rated at a "G" limit of 8 G. If you increase the weight of clean plane to 9,850lbs you lower the G limit to 6.5 G's
Which means you can start bending the plane at 6.5 Gs and break the plane several Gs lower than what it took to break the plane when it weighed 8,000lbs.
Heck, the Typhoon needed different wheels, tires an brakes to taxi with a pair of 1000lb bombs than it did with a pair of 500lb bombs. But hey, we can increase the weight of the Mustang by 2000lbs (a ton) and not have to make any changes?
FLYBOYJ
"THE GREAT GAZOO"
Or remove 2,000 pounds from the P-39!
You guys are milking the P39 discussion for everything it's worth haha.
Well if you use the Typhoon fuselage behind the engine to cope with the loads that would help? And to counter the weight at the front you could use the rear fuselage of the Typhoon (may need beefing up a bit). I am still working on the details but I have a name, how about "P-51 Tiffie"
Shortround6
Major General
You are going to wind up with a lot more dihedral on wings after you land than when you took off 
Well I was thinking, Typhoon wings and landing gear would help too?You are going to wind up with a lot more dihedral on wings after you land than when you took off
buffnut453
Captain
I was actually being sort of serious. If you start with a Sabre engine and decide you want a ground attack plane that carried the max bombs and guns, you end up with something that looks like a Typhoon. Slapping a Sabre engine in a P-51 so you can carry a bigger bomb load is sacrilege anyway.Get thee to the naughty corner...FORTHWITH!!!
FLYBOYJ
"THE GREAT GAZOO"
GregP
Major
Hi Nuuumannn. I think the OP was saying that the Mustang was rapidly designed for the Allison. Supposing they had chosen a different engine, could a Mustang-like aircraft have resulted? I' m not too sure he was saying design it for the Allison and then change it, but rather, pick an alternate engine and design a different "Mustang" that may or may notr resemble the real P-51.
Myself, I think like you ... if we stay with the Mustang design, the only real alternate is the merlin.
But, if was start with an alternate engine, then there are a LOT of possibilities. The questions is, what were the alternate engines than were sufficiently developed to be used in the new airplane during the time the actual P-51 was developed, around April 1940?
The Sabre was first run in 1938, but wasn't really mature until 1944 or so. I say it isn't really a contender in 1940. English Electric bought Napier in 1942 and quickly solved the issues, but it WAS 1944 before things were peachy with the Sabre.
The Centaurus was first run in 1938 but production didn't start until 1942.
The Girffon was first run in 1939, and the Girffon II first ran in 1940, so it is a possibility.
The R-2800 was first run in 1937, and was introduced at 2,000 hp in 1939, so it has to be a contender, too. The Mustang used a U.S.-built Allison engine to start with, so no objecting to a U.S. engine.
I'm guessing the engine had to be one these two if we skip the Allison. The design might be very similar if they used the Griffon, but would look completely different if they were with a radial.
Here is a picture of the Reno racer Shockwave.
or
On SHockwave, there is a unique fuselage, Hawker Sea Fury outer wings, and F-86 tail surfaces and uses an R-4360, but COULD have been designed around an R-2800 instead. Suppose they moved the pilot position forward to emulate a Sea Fury and had straighter tail surfaces. Then, we have a smaller Sea Fury around the late 1941 timeframe or a Mustang-like Griffon fighter around the same time.
Interesting to contemplate but, in a "what if," there are NO incorrect answers. We can always use the Startgate and imagine that benevolent aliens magically came down and solved the technical difficulties for us.
Yup, Greg, but my post you quoted was in direct response to his suggestion that because the Sabre worked in the Tempest and Typhoon it would work in the Mustang, hence my reply. If you go back to the beginning of the thread you'll see my reply to his original query is not so specific.
GregP
Major
H Nuuumannn. OK, I believe you are correct, as usual. Cheers.
I still like the Shockwave thing. I hope we eventually see it race. But, you never know. do you?
How about THIS one?
Might be a winner ...
I still like the Shockwave thing. I hope we eventually see it race. But, you never know. do you?
How about THIS one?
Might be a winner ...
It's hard to imagine what else to power the Mustang with, given its history and the outcome of re-engining it. The suggestion by the original poster of the Hisso Y12 makes for a less than convincing what if, though!
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Greg, in your post (#51), that mid-engined Mustang sure looks alot like the Me509 or R2Y1.
Yeah, it does. It's the Rolls-Royce Flying Test Bed, powered by a mid-ships mounted Griffon engine. A mock-up was built at Hucknall using bits from surplus Mustang I airframes, but the project was cancelled in February 1945.
GregP
Major
I confess ... it is straight off an internet group of fantasy conversions. I have no authorship on it.
Personally, I'd love to see an La-7 with an R-2800 and with another designer having a look at it. How about a Yak-3 with a Merlin 66 in it?
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Well, there was the Piaggio P.119 that had a radial engine mounted behind the cockpit - that might qualify
The alternative engine has to do what the Merlin actually did, have good power from take off to 25,000+ feet, be very efficient to get the range needed, be as light and with smallest cross section possible with still room for growth and above all else doing all that with the reliability to fly thousands of miles on escort missions, what other engine meets that criteria?.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
When the BPC approached North American about manufacturing P-40's under license, it was a whole different world in Europe.
The Merlins were being manufactured in England and at the time, there was a real concern wether England might be next to fall under Germany's onslaught.
North American drew up a design using what was available, tried and proven. The V-1710 was a solid performing engine and was, in my opinion, the right choice.
We can look back and ponder what-ifs, but at the time, no one knew that there would be a need for long-range escorts battling at 35,000 feet and the early Allison powered Mustangs were also excellent performers at lower altitudes (including the A-36).
