MOST OVERRATED AIRCRAFT OF WWII (1 Viewer)

GregP · Jul 13, 2016

The strategic situation was where it was because of earlier actions.

It didn't just evolve all on its own to suit the USAAF. Germany was PUT in that situation by the earlier war actions. Hitler was a former enlisted man, but even he should have know that a 3-front war is lost.

Shortround6 · Jul 13, 2016

The Strategic situation was what it was but even given the situation what other single seat land based day fighter could have done as well as the P-51B,C,D ?
The P-47 wouldn't have the range needed until the N showed up and that was too late.
The P-38 was the other US choice and while it sometimes is not given the credit it is due for the late versions they still weren't as good as the P-51.
The US might have been able to smash the Luftwaffe using P-47Ds and P-38J/Ls but it would have taken longer and cost more US lives.

What British fighter could have substituted for the P-51 from the spring of 1944 on?
Swap it around:
What German fighter could have flown the same escort missions?
What Russian fighter could have flown the same escort missions?
What Japanese fighter could have flown the same escort missions?

And P-51s could play fighter bomber and other missions (V-1 interceptor?)
P-51 not only maxed out with a 1000lb bomb under each wing, it could carry a pair of 500lb bombs on a mission radius of 400 miles if fitted with rear tank.

pbehn · Jul 13, 2016

The P51 was a pure enigma, no one can take away from its performance as Shortround has pointed out. However I would point out the following.

If the British didnt need fighters in 1940 it would not exist
If the British didnt take a chance on a new design it would probablynot exist.
If NA didnt produce it in the agreed time frame it would probably not exist
If the Merlin didnt fit in it it would have been a very sound but unremarkable tactical recon fighter
If German industry was as far away as Moscow it would be of n use and if it was as close as Belgium it wouldnt be needed.
If it didnt have a US champion to keep it in production as a dive bomber it probably would have been a "what if"
The role of escort fighter was first considered unnecessary and then considered impossible, when the role was proved to be needed and the P51 could do it it suddenly became obvious how great it was. Whether it was under rated or over rated it was surely the luckiest piece of machinery to exist. It combines the product of two industrial competitors doing a job that didnt exist before it took flight.

stona · Jul 14, 2016

Shortround6 said:
The US might have been able to smash the Luftwaffe using P-47Ds and P-38J/Ls but it would have taken longer and cost more US lives.

'Big Week'/Operation Argument in February 1944 was really the beginning of an effort to fulfill the requirements of the Pointblank Directive promulgated nine months earlier. It also announced a change in USAAF tactics. It is no coincidence that the date of 'Big Week' coincides with the culmination of the initial build up of US fighter forces in NW Europe AND the arrival of the P-51. From around this time the 8th AF fighter force essentially started to convert to the P-51, retaining almost none of the other types except in specialist roles (like P-38 reconnaissance types) and at 'stick in the mud' Groups like the 56th. The P-38 otherwise almost disappeared from this theatre, and the P-47 took on other important and complimentary roles with tactical forces.
It was clear to the 8th Air Force Command that the P-51 was the tool for the job, and with hindsight it is clear to us that it was correct.

At the time of 'Big Week' only a small proportion of 8th AF fighters were P-51s, but by the time the Luftwaffe was defeated towards the end of the year there was hardly anything else.

It's difficult to see how the P-51 can be overrated for it's effect on the campaign. It did a lot of things well and a few very well. You can say the same about any good aircraft.

Cheers

Steve

drgondog · Jul 14, 2016

pbehn said:
The P51 was a pure enigma, no one can take away from its performance as Shortround has pointed out. However I would point out the following.

If the British didnt need fighters in 1940 it would not exist
If the British didnt take a chance on a new design it would probablynot exist.
If NA didnt produce it in the agreed time frame it would probably not exist
If the Merlin didnt fit in it it would have been a very sound but unremarkable tactical recon fighter
If German industry was as far away as Moscow it would be of n use and if it was as close as Belgium it wouldnt be needed.
If it didnt have a US champion to keep it in production as a dive bomber it probably would have been a "what if"
The role of escort fighter was first considered unnecessary and then considered impossible, when the role was proved to be needed and the P51 could do it it suddenly became obvious how great it was. Whether it was under rated or over rated it was surely the luckiest piece of machinery to exist. It combines the product of two industrial competitors doing a job that didnt exist before it took flight.

All pretty good 'what if's' except that the 'US Champion' that found a way to bridge the end of the Mustang I and IA contract for NAA was Hap Arnold. He had made up his mind to a.) proceed forward with an AAF contract based on the merits demonstrated at Wright Pat and NACA Langley as well as the concept of armed recon, but had no clue regarding Merlin mod and b) pick the unused funding for additional Dive Bombers. That said, it is almost certain that he would have pushed for funding from another source absent the Dive Bomber slot. In rapid fire, the Brits completed their initial testing of the Mustang I and published the results on 1 May, 1941. In that report was the first push to try installing a Merlin 61. Then:

The A-36 contract was let April 16, 1942 - two weeks before the legendary "go Merlin decision had been made by RR/RAF' decision
NAA was drawn into the plan in late May.
The P-51A contract was let in June with a proviso that AAF could convert the balance of the orders with a P-51B should they so choose. The XP-51B contract was let in July,1942.
The P-51B contact in August, 1942

All before the first flight of the Mustang X.

drgondog · Jul 14, 2016

stona said:
'Big Week'/Operation Argument in February 1944 was really the beginning of an effort to fulfill the requirements of the Pointblank Directive promulgated nine months earlier.

A slightly different POV. Operation Argument was stimulated/prioritized as a subset of POINT BLANK when it became clear that the Combined Bomber Offensive failed to eliminate the threat that the LW posed to the Invasion. This was the true source of Doolittle's pronouncement (and incentive plan to rank a ground score the same as air to air toward "Ace") to "Destroy the LW in the air and on the Ground".

It also announced a change in USAAF tactics. It is no coincidence that the date of 'Big Week' coincides with the culmination of the initial build up of US fighter forces in NW Europe AND the arrival of the P-51. From around this time the 8th AF fighter force essentially started to convert to the P-51, retaining almost none of the other types except in specialist roles (like P-38 reconnaissance types) and at 'stick in the mud' Groups like the 56th. The P-38 otherwise almost disappeared from this theatre, and the P-47 took on other important and complimentary roles with tactical forces.

The P-38 survived as important LR escort within 8th AF operations until the late July timeframe then dribbled down to 474th in September, but the 9th AF added 367th and 370th in May, All of the 8th and 9th AF FG's flew escort missions under operational control of 8th AF as well as 354th and 363rd FG (P-51s) until late May 1944. The chart not only fails to include the Very Important operational contributions of 354th FG (Dec 1, 1943 through May 29, 1944) but also 363rd FG (Feb 22, 1944 through May 29, 1944) dedicated to 8th AF escort role. The initial ramp up began in February and March when the Mustang force structure for Argument was 4 in Feb, 5 in March and, 6 in April, 1944

It was clear to the 8th Air Force Command that the P-51 was the tool for the job, and with hindsight it is clear to us that it was correct.

At the time of 'Big Week' only a small proportion of 8th AF fighters were P-51s, but by the time the Luftwaffe was defeated towards the end of the year there was hardly anything else.

As noted above, the 4th, 357th, 354th and 363rd were dedicated from Big Week forward but the P-51 contribution to the destruction of the LW was disproportionate to the combine P-38?P-47 FG's.

It's difficult to see how the P-51 can be overrated for it's effect on the campaign. It did a lot of things well and a few very well. You can say the same about any good aircraft.

Cheers

Steve

The key attribute of the P-51B/C was that they made possible the continuation of the Daylight phase of Operation and were the main contributor to the daylight destruction of the LW prior to D-Day. Take what you want relative to its mantle of most important fighter in 1944, 1945 but defeat of Germany was #1 Priority of the Allies..

pbehn · Jul 14, 2016

drgondog said:
All pretty good 'what if's' except that the 'US Champion' that found a way to bridge the end of the Mustang I and IA contract for NAA was Hap Arnold. He had made up his mind to a.) proceed forward with an AAF contract based on the merits demonstrated at Wright Pat and NACA Langley as well as the concept of armed recon, but had no clue regarding Merlin mod and b) pick the unused funding for additional Dive Bombers. That said, it is almost certain that he would have pushed for funding from another source absent the Dive Bomber slot. In rapid fire, the Brits completed their initial testing of the Mustang I and published the results on 1 May, 1941. In that report was the first push to try installing a Merlin 61. Then:

The A-36 contract was let April 16, 1942 - two weeks before the legendary "go Merlin decision had been made by RR/RAF' decision

NAA was drawn into the plan in late May.

The P-51A contract was let in June with a proviso that AAF could convert the balance of the orders with a P-51B should they so choose. The XP-51B contract was let in July,1942.

The P-51B contact in August, 1942

All before the first flight of the Mustang X.

Great post, I was quoting from memory, the story is convoluted and much of it written in hindsight.

Just one question, would it have been commercially possible for the British to specify a plane designed around the Merlin in 1939/40. I know merlins were wanted by all branches of the british military but if the first flight of the Mustang was with a Merlin it may have speeded things up.

Shortround6 · Jul 14, 2016

pbehn said:
Great post, I was quoting from memory, the story is convoluted and much of it written in hindsight.

Just one question, would it have been commercially possible for the British to specify a plane designed around the Merlin in 1939/40. I know merlins were wanted by all branches of the british military but if the first flight of the Mustang was with a Merlin it may have speeded things up.

It wouldn't have speeded things up by much, even assuming you could find a few spare Merlins in the fall of 1940. The single stage Merlins were roughly 250-300lbs lighter than the 2 stage engines, the P-51B used a prop that weighed roughly 100lbs more than the prop on the Allison models. SIngle stage Merlins and Allisons need different radiators and oil coolers from each other. The two stage engine is going to need bigger radiators and oil coolers let alone adding the inter-cooler so the whole radiator/oil cooler duct would have to be redone in any case.

There were roughly 1580 Allison powered Mustangs (counting A-36s) and they were used in Europe, the Med and the Far East. Coming up with 2100-2400 extra Merlins (including spares) during late 1941-42 and early 43 might be a bit of a problem without shorting several other programs. MAYBE you could swipe all the Merlins used to power the P-40Fs and Ls, Not sure how that would play out with more Es, Ks and Ms in use and needing more Spitfires and single stage Merlin Mustangs to fly top cover for them?

drgondog · Jul 15, 2016

Pbehn asked "Just one question, would it have been commercially possible for the British to specify a plane designed around the Merlin in 1939/40. I know merlins were wanted by all branches of the british military but if the first flight of the Mustang was with a Merlin it may have speeded things up.

The Merlin availability was the gating factor. Not just availability, but track record solid enough to prioritize as The in-line power plant - solid enough to bet the farm at NAA during pre-design of NA-73, solid enough to re-direct Griffon and other in-line engine production to Merlin to meet demand. I don't think it was a commercial issue, but a timing and reputation and foreknowledge of the Merlin development potential.

I don't recall that RR had the manufacturing capacity to keep pace with the Hurricane, Spitfire, Mosquito, Lancaster development and production - nor supply RCAF production

Regarding earlier development of the P-51B? Had Packard Merlin started delivering 1650-1's in early 1939 (impossible based on RR Merlin development lifecycle, the License discussion cycle, much less the amount of time to reproduce to US tooling and parts standards), then the 1650-1 may have been the selected engine for the XP-51... and the airframe would have been ready earlier (nearly, because the two stage S/C required changes to firewall and engine mounts).

As SR noted, Introducing the 1650-3 would have required changes to Radiator/oil cooler system but would not have to move the wing and change the firewall which were Major structural changes

But recall that NAA had more than 100 P-51B-1 airframes completed awaiting deliveries of the production 1650-3 engines caught up to NAA production from May to July, 1943.

That is an incredible stretch given AAF high command inclination to 'buy American' and not much was even known about the Spitfire and no two stage two speed in-line engines were ready to drop in. Had Allison been funded in 1938 with high altitude performance as a spec - then perhaps the Mustang could have been immediately available in 1942.

pbehn · Jul 15, 2016

Great info guys. One part of my question was about the legality, would the USA sanction airframes being shipped abroad given a hypothetical abundance of merlins from the merlin tree?

drgondog · Jul 15, 2016

pbehn said:
Great info guys. One part of my question was about the legality, would the USA sanction airframes being shipped abroad given a hypothetical abundance of merlins from the merlin tree?

The US approved British order for Model 322 Lightnings in June 1940.

Timppa · Jul 15, 2016

Ilyushin Il-2.

Known for its toughness, yet shot down in droves.

Shortround6 · Jul 15, 2016

drgondog said:
The US approved British order for Model 322 Lightnings in June 1940.

A correction from "AHT" The British ordered 143 model 322s in March of 1940.
June 5th 1940 saw the US give approval for an order of 524 Lightning MK IIs with turbo superchargers.

1939 and 1940 certainly saw the delivery of hundreds of Hawk 75s, some Hawk 81s, and plenty of Lockheed Hudsons, Martin Marylanders, Douglas DB-7s/Bostons/Hovacs and Grumman Wildcat/Martlets and others. Doesn't seem to be a big problem although a few planes did have to resort to some sort of skulduggery in order to make it out of the country.

davparlr · Jul 17, 2016

Here's a question from left field. Could the the two stage supercharger for the Merlin been adapted to Allison engine, and, if so could it have been produce quicker and in sufficient quantities to upgrade the Allison P-51s and provide a very capable high altitude fighter maybe a year earlier? Does the the development of the two stage supercharger support this scenario?

wuzak · Jul 17, 2016

davparlr said:
Here's a question from left field. Could the the two stage supercharger for the Merlin been adapted to Allison engine, and, if so could it have been produce quicker and in sufficient quantities to upgrade the Allison P-51s and provide a very capable high altitude fighter maybe a year earlier? Does the the development of the two stage supercharger support this scenario?

Yes, it could have.

I think that, if anything, the conversion would take longer. It would require setting up the supercharger manufacturing facility and modifying the design to suit the Allison. It would then need to go through reliability testing, etc.

Packard were already building the V-1650-1. It was far easier for them to change to 2 stage production (the V-1650-3) than it would be for Allison.

The V-1710 was run in conjunction with a Merlin 2 stage supercharger (around 1944 IIRC), but it wasn't connected directly to the engine. Performance was near enough identical to the Merlin.

Shortround6 · Jul 18, 2016

In a lot of engines the "back half" of the supercharger is part of the engine casting or at least the mounting bosses/points are. adding and subtracting superchargers is not quite as easy as doing it on car engines. Perhaps all that is needed is a new crankcase mold for casting, perhaps not.
Aircraft superchargers take several hundred horsepower to drive. The two stage superchargers could take 3-400hp and so need substantial drive mechanisms. It took Allison about a year to deliver single stage engines using 9.60 drive gears because they needed to increase the thickness of the drive gears to handle the load over using 8.80 gears. This required new castings. The Merlin required new supercharger drive components to go from 15lbs boost to 18lbs and above. They broke supercharger drive shafts on occasion in testing
when trying for 18lbs boost.
IIRC correctly Allison went through several (3?) Merlin superchargers when doing the testing referred to by Wuzak. They suffered bearing failure in the superchargers. The first stage of the Merlin supercharger was an 11.5- 12in diameter impeller spinning at 24,000rpm plus so any misalignment or vibration in the drive system could mess things up in a hurry. How much the crankcase acted like a heat sink or contributed to the supercharger cooling might also be a factor. AIr in the supercharger could easily be at a higher temperature than the engine coolant and oil. Perhaps the bearing failures were due to excessive oil temperature in the bearings?
Service use of the copied supercharger could only come at the end of a thorough testing phase.

davparlr · Jul 19, 2016

Thanks wuzak and SR6 for the great info, as I expected from you guys. I was just thinking that it would have been easier to adapt another supercharger than to create an entirely new engine plant, but that would have been needed anyway.

V-1710 · Jul 21, 2016

Take a look at the 2 stage supercharged Allison used in the P-63. It was a novel design, using a fluid coupling to drive the second stage, and performed well at high altitudes. May not have been practical for installation in a Mustang though.

drgondog · Jul 21, 2016

pbehn said:
Great post, I was quoting from memory, the story is convoluted and much of it written in hindsight.

Just one question, would it have been commercially possible for the British to specify a plane designed around the Merlin in 1939/40. I know merlins were wanted by all branches of the british military but if the first flight of the Mustang was with a Merlin it may have speeded things up.

I forgot to answer this. According to Lee Atwood, the NAA contract with the British Purchasing System agreed to Brit authority for all Brit furnished equipment, including engine change if so specified.

RCAFson · Jul 21, 2016

Shortround6 said:
It wouldn't have speeded things up by much, even assuming you could find a few spare Merlins in the fall of 1940. The single stage Merlins were roughly 250-300lbs lighter than the 2 stage engines, the P-51B used a prop that weighed roughly 100lbs more than the prop on the Allison models. SIngle stage Merlins and Allisons need different radiators and oil coolers from each other. The two stage engine is going to need bigger radiators and oil coolers let alone adding the inter-cooler so the whole radiator/oil cooler duct would have to be redone in any case.

There were roughly 1580 Allison powered Mustangs (counting A-36s) and they were used in Europe, the Med and the Far East. Coming up with 2100-2400 extra Merlins (including spares) during late 1941-42 and early 43 might be a bit of a problem without shorting several other programs. MAYBE you could swipe all the Merlins used to power the P-40Fs and Ls, Not sure how that would play out with more Es, Ks and Ms in use and needing more Spitfires and single stage Merlin Mustangs to fly top cover for them?

I suspect that the UK would have been willing to forgo some Hurricane production if it meant fitting their engines into Mustangs. Also if Ford hadn't decided to pull out of the Merlin engine deal, Ford would probably have had the Merlin in volume production ~6 months sooner than Packard and Ford volume production would have been somewhat higher, sooner, compared to Packard.

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