Merlin engined P40

[Shortround6]

P40 's were actually designed as a fighter bomber, hence the low end super charging.

Which P-40s were designed as fighter bombers?

This is among the Great Myths of WW II Aviation. The P-40 (no letter) was designed to be the best high altitude fighter the US Army could get in numbers in 1940. Not 1941 or in 1942.
The Army knew the Turbo charged P-38 and P-35 offshoot that became the P-43 were not going to be ready for squadron service in 1940. Allison could offer an engine that gave 1040hp at 14,300ft which was better than anything anywhere except the Merlin III (this was the Spring of 1939)
Now things get a little confusing because the Army doesn't get what they ordered right away. The $12,872,398.00 order to Curtiss on April 27th 1939 for 560 aircraft (524 complete aircraft and 36 as spare parts) takes a while to get going and Allison has to tool up to make the engines. The first Production P-40 wasn't flown until April 4th 1940 and it wasn't accepted by the Army for 3 weeks.
The confusion really sets in with the Army agreeing to defer deliveries so the French and British can get aircraft that they had ordered in 1939/early 1940. The Army doesn't get the 524 aircraft they ordered. They get 200(?) and take deliveries of of the rest as P-40Bs and P-40Cs.
To keep things short, the P-40 no letter and the P-40B did not have a belly rack for either fuel tank or bomb. That doesn't show up until the P-40C. The Early British (ex French) Tomahawks did not have the belly rack either. There are some sources that claim that the early versions could have under wing racks for small bombs.
Now the early versions with the under fuselage tank were not intended for bombing. It was found (by several people?) that they could sling a 500lb under the fuselage using the drop tank fittings.
In Fact the manual for the P-40D & E published April 25th 1941 and revised Sept 5th 1941 makes no mention of using a bomb underneath the fuselage. They do say that 3 20lb bombs can be carried underneath each wing with either M42 fragmentation bombs or type T7 practice bombs. Manual lists both manual release type and electrical release type (trigger).

As we all know the P-40D&E did carry bombs under the fuselage in service. But the fact that the P-40 was designed as a fighter bomber is a myth. It was adopted into one.
The type of engine used was what they could get their hands on, not a choice because they only intended the plane to be flown at low altitude.

 

[MiTasol]

Something I've encountered a lot is when people think Merlin engine, they immediately think of the Mustang and the Merlin 61 believing it was some kind of super engine not realizing it was, as you say, the two stage two speed supercharger.

P40 's were actually designed as a fighter bomber, hence the low end super charging. In North Africa P40s were encountering a lot of air opposition but in Italy there wasn't as many axis fighters to deal with IIRC so they could carry on without being bothered as much.

If the P-40 Warhawk had been designed as a fighter bomber it would have an A- designation for attack just like used on the A-36 fighter bomber version of the P-51. There never was an A version of the Warhawk series of aircraft.

The P designation indicates they were designed as a pursuit (fighter) aircraft from day one.

And the reason the Allison only had a "low altitude" supercharger is because that is what the US Army demanded.

 

[Frog]

Not really - Packard was producing the V1650-1s used in the P-40F/L, and also the 2-Speed Merlin 28, 38, and 224sseries engines used in some Hurricanes, and the Lancaster Mk III and the Canadian Lancaster Mk Xs.
Plus all the 2-stage Merlins for the P-51, Several different marks of Spitfire - It was only at the end of the War that a second American Merlin production line was set up - Continental Motors produced a few, then the war ended, and all U.S. Merlin production stopped (Licensing agreements, and demand.)

The 797 V 1650s produced by Continental were installed on P-51s.

 

[CD Baumann]

If the P-40 Warhawk had been designed as a fighter bomber it would have an A- designation for attack just like used on the A-36 fighter bomber version of the P-51. There never was an A version of the Warhawk series of aircraft.

The P designation indicates they were designed as a pursuit (fighter) aircraft from day one.

And the reason the Allison only had a "low altitude" supercharger is because that is what the US Army demanded.

No. Both it and the P39 were designed for ground attack, with a secondary fighter capability, under prewar doctrine. The idea was the P40's and P39's would attack ground troops of an invading army while the P38's would take care of bombers per Fork Tailed Devil by Martin Caiden. It's also mentioned in his book about the B17.

And the A36 was a dive bomber. Any attack bomber/dive bomber got the "A" designation. Hence the Dauntless was redesignated as A24 by the USAAF.

 

[wuzak]

No. Both it and the P39 were designed for ground attack, with a secondary fighter capability, under prewar doctrine. The idea was the P40's and P39's would attack ground troops of an invading army while the P38's would take care of bombers per Fork Tailed Devil by Martin Caiden. It's also mentioned in his book about the B17.

And the A36 was a dive bomber. Any attack bomber/dive bomber got the "A" designation. Hence the Dauntless was redesignated as A24 by the USAAF.

No, both the P-38 and P-39 were designed as interceptors.

That is, they were to climb fast to high altitude to tackle incoming bombers.

The XP-39 was designed and fitted with a turbocharger. But the installation, particularly regarding the intercooler, was poor and the turbo dropped.

The P-40 was an upgraded P-36, a fighter.

The P-40 might not have existed had the XP-37 and YP-37 not have issues with its design - from the poor pilot position, to the unreliability of the turbocharger.

I've never read Caiden, but he doesn't have a stellar reputation in here!

 

[CD Baumann]

No, both the P-38 and P-39 were designed as interceptors.

That is, they were to climb fast to high altitude to tackle incoming bombers.

The XP-39 was designed and fitted with a turbocharger. But the installation, particularly regarding the intercooler, was poor and the turbo dropped.

The P-40 was an upgraded P-36, a fighter.

The P-40 might not have existed had the XP-37 and YP-37 not have issues with its design - from the poor pilot position, to the unreliability of the turbocharger.

I've never read Caiden, but he doesn't have a stellar reputation in here!

No, both the P-38 and P-39 were designed as interceptors.

That is, they were to climb fast to high altitude to tackle incoming bombers.

The XP-39 was designed and fitted with a turbocharger. But the installation, particularly regarding the intercooler, was poor and the turbo dropped.

The P-40 was an upgraded P-36, a fighter.

The P-40 might not have existed had the XP-37 and YP-37 not have issues with its design - from the poor pilot position, to the unreliability of the turbocharger.

I've never read Caiden, but he doesn't have a stellar reputation in here!

I'm assuming you're referring to that big boxy monstrosity they fitted to the bottom of an Airacobra fuselage that caused too much drag? It was never installed in production P39's to my knowledge and thus relegated to lie altitude.

As far as I know the P40 was kind of the plan B for the YP37 because, as you say, they couldn't get turbo to work.

The P36 may have been a thoroughbred fighter but that doesn't mean it's successor was.


I politely encourage you to read them and come to your own conclusions. I gotta tell you, I don't do this "he has a bad rep around here" nonsense because I'm going to tell you something, I try to double check everything and while I know Caiden has a rep for storytelling, but all the facts mentioned in his books line up from what I can tell because what I stated above is backed up by Jeff Ethell's book on the P40.

 

[special ed]

The P-38, P-39 and P-40 were initially all interceptors as any attack on the U.S. would be coming in the air. No need for strafing ground troops. As with all fighters, as the type ages, they are assigned more to close support of our troops as newer fighters do the air to air fighting. Brother Martin has fiction and opinion in with his facts. I have most of his books, including his works of fiction.

 

[wuzak]

Circular Proposal X-609
[edit]
In February 1937, Lieutenant Benjamin S. Kelsey, Project Officer for Fighters at the United States Army Air Corps (USAAC), and Captain Gordon P. Saville, fighter tactics instructor at the Air Corps Tactical School, issued a specification for a new fighter via Circular Proposal X-609.[7]​ It was a request for a single-engine high-altitude "interceptor" having "the tactical mission of interception and attack of hostile aircraft at high altitude".[8]​ Despite being called an interceptor, the proposed aircraft's role was simply an extension of the traditional pursuit (fighter) role, using a heavier and more powerful aircraft at higher altitude. Specifications called for at least 1,000 lb (450 kg) of heavy armament including a cannon, a liquid-cooled Allison engine with a General Electric turbo-supercharger, tricycle landing gear, a level airspeed of at least 360 mph (580 km/h) at altitude, and a climb to 20,000 ft (6,100 m) within six minutes.[9]​

From Wiki.

Bodie, Warren. The Lockheed P-38 Lightning. St. Paul, Minnesota: Widewing Publications, 1991. ISBN 0-9629359-5-6., p. 19.
Bodie, Warren. The Lockheed P-38 Lightning. St. Paul, Minnesota: Widewing Publications, 1991. ISBN 0-9629359-5-6., pp. 16–17.
Lockheed P-38 Lightning. Retrieved: 21 January 2007.

If someone has access to Circular Proposals X-609 (P-39) and X-608 (P-38), that would be a much better source.

 

[CD Baumann]

The P-38, P-39 and P-40 were initially all interceptors as any attack on the U.S. would be coming in the air. No need for strafing ground troops. As with all fighters, as the type ages, they are assigned more to close support of our troops as newer fighters do the air to air fighting. Brother Martin has fiction and opinion in with his facts. I have most of his books, including his works of fiction.

Are you sure?
American fighter Plane by Ted and Amy Williams.

 

[special ed]

Absolutely certain. Ted and Amy are not experts, but rewrite what others have written. My opinion, like it or not.

 

[wuzak]

Are you sure?
American fighter Plane by Ted and Amy Williams.

Is this the part you are referring to?

Essentially, the P39 was designed to be an efficient, airborne way to deliver heavy fire to the enemy

Doesn't exactly say if the enemy was in the air, or on land or sea.

Note that the P-38 was also designed with the 37mm M4 cannon.

As was the Bell XFM-1/YFM-1, which carried two aimable 37mm M4 cannons. And that was designed as a bomber destroyer.

The XP-67 was to be fitted with 6 M4s to destroy bombers, and the XP-54 was to have two.

The XP-54 had a pressurised cockpit for high altitude operation.

The XP-54 and XP-67 had their origins in Circular Proposal R40C, which sought fighters of the highest possible performance, beyond what was in service at the time and was expected to be in service in the near future

If the P-39 was to be designed as a ground attack aircraft, you would thinki it capable of carrying more bombs, and more ammunition (30 rounds for the M4 initially?).

 

[CD Baumann]

Is this the part you are referring to?



Doesn't exactly say if the enemy was in the air, or on land or sea.

Note that the P-38 was also designed with the 37mm M4 cannon.

As was the Bell XFM-1/YFM-1, which carried two aimable 37mm M4 cannons. And that was designed as a bomber destroyer.

The XP-67 was to be fitted with 6 M4s to destroy bombers, and the XP-54 was to have two.

The XP-54 had a pressurised cockpit for high altitude operation.

The XP-54 and XP-67 had their origins in Circular Proposal R40C, which sought fighters of the highest possible performance, beyond what was in service at the time and was expected to be in service in the near future

If the P-39 was to be designed as a ground attack aircraft, you would thinki it capable of carrying more bombs, and more ammunition (30 rounds for the M4 initially?).

Because close support means generally means ground attack at least in modern parlance. And the last I checked, bombers tend to be in the air when they drop their bombs.
That's not to say they could shoot other planes down because they obviously did.
And I fail to see what the other aircraft you mention have to do with it.

 

[CD Baumann]

Absolutely certain. Ted and Amy are not experts, but rewrite what others have written. My opinion, like it or not.

Yes there's a name for that, it's called research.
So suddenly because it doesn't agree with you, they don't know what they're talking about about?

Ooookaay then.

 

[MIflyer]

And we even had some not only in the the Western Desert but also at Guadalcanal.

 

[CD Baumann]

And we even had some not only in the the Western Desert but also at Guadalcanal.

View attachment 794618

Was there a law saying they could send them to Guadalcanal?

 

[MIflyer]

Was there a law saying they could send them to Guadalcanal?

I think it funny that the USAAF had P-40's with Merlin engines in the Pacific while the NZ and Aussies did not.

 

[CD Baumann]

I think it funny that the USAAF had P-40's with Merlin engines in the Pacific while the NZ and Aussies did not.

Ironic right?

 

[ThomasP]

re

Was there a law saying they could send them to Guadalcanal?

??

I do not understand this question. What kind of law would be necessary?

 

[Shortround6]

If the P-39 was to be designed as a ground attack aircraft, you would thinki it capable of carrying more bombs, and more ammunition (30 rounds for the M4 initially?).

It actually had 15 round in the early versions.

There are a lot of threads debunking this "designed" as ground attack aircraft nonsense over the years in this forum.

Nobody yet has produced a document that shows that the USAAC was looking for "ground" attack aircraft or that shows that the P-39 and P-40 were tailored for low altitude work.
Low altitude in refence to 1938-39, not low altitude in 1941/42 and later. A lot of writers used the retrospectroscope even in the 1950s and 60s.

Standard Army "Attack" planes carried four .30 cal guns for strafing. This went from the about the A-3 through the A-20 (early versions) the the desired bomb load/s were large quantities of small fragmentation bombs. Started with 200lbs on the A-3 (435hp Curtiss D-12 engine) and the bomb load was increased as engines got more powerful. By the A-8 the guns were ALL outside the propeller arc. By the A-17s the bomb load was normally around 600lbs which was comprised of twenty 30lb fragmentation bombs. These were the planes that were being delivered in 1937.
Now the P-36 carried one .50 cal and one .30 in cowl as standard armament. With 200rounds of .50 cal ammo and 500 rounds of .30 cal ammo, and no bombs in US service(?).
The XP-40 carried two .50 cal guns and the production planes are listed with either two .50 cal guns or two .50s and two .30s (more modern books) which is actually not that good for ground strafing.
The early P-36s had engines that were rated for 900hp at 10,000ft. Later ones with 100 octane fuel were rated at 1050hp at 6,500ft. The P-36B (one built) was given an engine rated rated at 950hp at 14,300ft. It was later changed for the same engine the other P-36Cs had. They didn't like the loss of 100hp for take-off that the higher altitude engine had. All single speed, single stage engines.

So let's take another look at the "designed" for ground attack (or at least, fighting enemy low altitude ground attack planes) P-40. No bombs, or at best (?) six 20lbs bombs? two .50 cal guns with not much ammo, when the extra pair of .30s showed up? Ordered in April 1939. First plane shows up in April of 1940. Needing more armament than the asked for pair of .50s was becoming rather evident from combat in Europe.
And the P-40 got an engine that gave 1040hp at 14,300ft. (9.5% increase at 14,300ft) now please note that Allison could supply engines that gave 1150hp near sea level using different supercharger gears. So where are the attributes that would show that the P-40 was 'designed' for low altitude work? Best high altitude engine the US could get in quantity. (P & W could not supply even close to 300 two stage R-1830s in 1940-41) and the bomb racks were either non-existent or vestigial and the gun armament was certainly nothing to brag about for strafing.

Let's also look at the fighters actually built in America in 1940 both for domestic and foreign use. 1685 Fighters were built of all types.
Lockheed, the Defender of America's high altitude spaces, built one P-38. Yes One, in Sept.
Bell built 13 YP-39s in 1940, 10 of them in Dec. They built II YFM-1s/1As/1bs.
Republic built 2 P-43s (and about 106 P-35A/EP-1s)

Curtiss built 481 P-36s/Hawk 75s
Curtiss built 778 P-40, P-40G and H81A aircraft.

The bulk of the remainder were navy fighters, like 160 Buffalos of assorted varieties.

The P-40 was not designed for low altitude work. It was designed and ordered to be the best all round fighter the US could build in quantity in 1940 and 1941.
In 1941 Curtiss (and Allison) built 2248 P-40s. Bell built 926 P-39s. Lockheed built 207 P-38s.
You want the US to wait for higher altitude fighters with turbo Allisons (or turbo anything) or with mechanical two stage superchargers?

Hundreds if not over 1000 fewer fighters built in 1940-41 for the US and the Allies.

 

[MiTasol]

I'm assuming you're referring to that big boxy monstrosity they fitted to the bottom of an Airacobra fuselage that caused too much drag?

As far as I know the P40 was kind of the plan B for the YP37 because, as you say, they couldn't get turbo to work.

The P36 may have been a thoroughbred fighter but that doesn't mean it's successor was.


I politely encourage you to read them and come to your own conclusions. I gotta tell you, I don't do this "he has a bad rep around here" nonsense because I'm going to tell you something, I try to double check everything and while I know Caiden has a rep for storytelling, but all the facts mentioned in his books line up from what I can tell because what I stated above is backed up by Jeff Ethell's book on the P40.

Dig out the specification that the P-40 was designed to meet and you will find PURSUIT only. I do not have a copy but at least one copy is floating around here.

As has already been mentioned the model 87 was the first to carry bombs. None of the model 81 aircraft in USAAC/F, RAF or French service carried bombs or drop tanks.