1937-45: Doubling down on the 2-engined 'day fighters' (1 Viewer)

[tomo pauk]

If bomber interception is the mission you are doubling the fuel consumption per mission, which with the fuel situation in 1940 is not a good idea.
To justify a twin merlin for the interception role it must be twice as effective per mission (ie double the kills) for the same expenditure of resources.

How effective in the bomber killing business were the Gladiators, Defiants and fighter Blenheims in 1940?

 

[Dimlee]

Thinking about Do 335 and Fokker D.XXIII and similar designs... I just discovered this good thread:

Tandems (and push pulls, maybe?)

Something that has seen surprisingly little discussion even here. Why was there no successful tandem or push pull twin? The only ones to ever reach production (sorta kinda) I can think of were the VB 10 and Do 335 respectively. Both pretty much pointless by the time they came out, Do 335's job...

ww2aircraft.net

 

[tomo pauk]

The P-322 (turboless P-38) was rejected by the British and the USAAF only used it at home as a training plane - because it was simply not good enough.

P-322 used by USAAF for training was not the same as the Lightining I - the former was with the low-altitude V-1710s, the later was with 'normal' altitude V-1710s. It can be only expected that the former will be lower performing.
Problem with the Lighting I was that it took some 20 months between the contracts signed and 1st piecemeal deliveries (some people don't like me doing this, but I put the most of the blame on Lockheed for the huge delays of the P-38 program), that was not helped with Allison making no progress on altitude power of their engine between mid-1940 and mid-1942, while both Germans and British made huge improvements in that time. Even the Japanese were outfitting their fighters with engines with better altitude power by mid-1941.
From the British perspective, that were supposed to pay cash (= gold) for the Lighting I and II (= turboed version), it looked the worse money spend by every day already past late 1940.

 

[Shortround6]

The RAF took on those in the pipeline already but found them unsatisfactory as delivered and wanted no more and spent their money on Hawk81 Tomahawks to replace the Lysanders in Army C-operation Command initially.

The time line doesn't work. The first P322 didn't leave the production line until Aug 1941, What the British did or did not know about it is subject to question, The first P-322 to get to Britain doesn't get there until Dec 1941, how soon it is tested I don't know. The 2nd P-322 Arrived in England in Jan 1942. Yes they wanted no more of them but.............BIG BUT...

By Aug 21st 1941 (about the time the first one is rolled out the door) Curtiss has built 694 H81A-2 and -3 aircraft had been built for the British. In fact in April of 1941 #3 squadron of the SAAF gets Tomahawk IIBs in North Africa. And on May 7th 1941 the British order 420 P-40Es, This is just about 1 year after they ordered 560 H87A Kittihawks.

They may have gotten a lot more for their money with the Curtiss machines but they did not spend the money on Tomahawks that they 'saved' on the P322s. the money for the Tomahawks had already been paid to Curtiss.
In fact the British had ordered a total of 620 NA Mustangs back in Sept of 1940. The First Mustang showed up in England about two months before the first P322.

British gave the Tomahawk Is to the Army Co-operation squadrons because they didn't know what else to do with them. The Tomahawk Is (ex French contract?) didn't have self sealing tanks and had little or no armor or BP glass. After the BoB the British were NOT going use them as fighters in a combat theater.

 

[Zmauky]

The USAAF used the original Lightning I - part as P-322-I (with Allison C) and the rest with newer (short gearbox) Allison as P-322-II.
And RS models has both variants (with associated different engines) as models in 1/72 .
However, this does not change the fact that when the first Lightning I units finally arrived in the UK for testing (March 1942), they were not exactly top class.
Although I have to admit that the Lightning I with long Alison C resembles the XP-38 and looks better than the P-38D-H.

 

[Shortround6]

P-322 used by USAAF for training was not the same as the Lightining I - the former was with the low-altitude V-1710s, the later was with 'normal' altitude V-1710s. It can be only expected that the former will be lower performing.

There may have been 3 engines used the Lightning Is?
about 20 were supposed to have gotten the original long nose (P-40 style) -15 engines that maxed out at 1040/1090hp even for take off (unless abused)
The Rest are supposed to have gotten handed V-1710-27 and -29 engines which used 6.44 supercharger gears and no turbos. These engines would give 1150hp but only at very low altitudes. As the war went on some of them may have gotten -49/-53 engines as replacements but still without turbos?

 

[Zmauky]

According to Lightning I for RAF
Lightning I - originally-specified V-1710-15 but ...
Twenty of the P-322s retained their V-1710-C15 engines (USAAF designation V-1710-33 that would be last C model Alison) with unhanded propellers. The rest of the P-322s were fitted with manual engines (V-1710-27 and -29 that should be F model Alison same as USAAF ) but were not given turbosuperchargers. Only one Lightning II (AF221) was completed. It was taken over by the USAAF as P-38F-13-10.
Actually, it's strange that, when they were already putting the newer Alisons in P-322, they didn't put a turbo and produce them like regular P-38s.

 

[Shortround6]

Actually, it's strange that, when they were already putting the newer Alisons in P-322, they didn't put a turbo and produce them like regular P-38s.

Maybe they didn't have an extra 240 turbos?
Or the wing leading edges were not set up to be inter coolers?

Why they didn't stick 8.80 gears in the engines to restore even 10-15,000ft performance?
Maybe they didn't even stick oxygen equipment in them and kept them at really low altitudes?

 

[Zmauky]

Yes, of course I agree, but they must have put in some effort to change the Alison C to the Alison F (same difference between P-40B and D), and now maybe there were no more C models, so they had to or ... in any case, at that time the USAAF would probably have been happier with 200+ fighters but just as many training ones. So why not go another kilometer or mile.

Or the wing leading edges were not set up to be inter coolers?

? Meaning

 

[Shortround6]

? Meaning

I can't find any online pictures.
Early P-38s used the outer wing edge as the intercooler, on the later Js that was converted to fuel storage.
I don't know which way the air flow went but the hot air from the turbo charger was routed through the wing edge to be cooled off and then returned though pipes/ducts to the carb inlet. Which means the wing leading edge has to be air tight from about the engine nacelles to the near the tip and the pipes/ducts that either return the cooled air from the tips (or mover the hot air out to the tips) also have to be airtight or else you loose the pressure from the turbos.
If you don't have turbos you just have to make an intake duct to the carb inlet. Sealing up the leading edge for a non turbo plane sounds like a lot of work for the factory and even more work to take the lead edge apart and seal it up if you are trying to convert the aircraft over from non turbo to turbo

 

[Zmauky]

Really interesting, I didn't really pay attention, i.e. somehow I concluded that the coolers in the tail beams are for the glycol/oil , and the two small ones under the spinner are intercoolers for air from the turbo.
And now I know something new.

 

[Geoffrey Sinclair]

Rolls Royce figures, Merlin production

165 Jan-39
195 Feb-39
189 Mar-39
151 Apr-39
205 May-39
198 Jun-39
193 Jul-39
135 Aug-39
261 Sep-39
281 Oct-39
273 Nov-39
326 Dec-39
401 Jan-40
287 Feb-40
293 Mar-40
385 Apr-40
614 May-40
880 Jun-40
706 Jul-40
648 Aug-40
693 Sep-40
746 Oct-40
749 Nov-40
561 Dec-40
679 Jan-41
642 Feb-41
810 Mar-41
647 Apr-41
761 May-41
784 Jun-41
859 Jul-41
947 Aug-41
1,189 Sep-41
1,398 Oct-41
1,393 Nov-41
1,341 Dec-41
2,572 in 1939
6,963 in 1940
11,450 in 1941.

First engines, Crewe June 1939, Glasgow November 1940, Ford August 1941.

Merlin VIII from November 1939 (plus 4 March/April), Merlin X in production in 1938, Merlin XII 5 built September 1939 to February 1940 then from April 1940, Merlin XX from July 1940, Merlin XII from February 1941, Merlin 30 from November 1940, Merlin 45 from January 1941, Merlin 46 from October 1941, Merlin 47 from December 1941, Merlin 60 from November 1941.

Apart from Merlin Derby turned out 415 Vulture and 293 Peregrine 1939 to 1941 inclusive plus converted 1,039 Kestrel to mark XXX.

23 P-322 November 1941 to January 1942, 120 more in July 1942. The USAAF Delivery logs record AE981 to 994, 996, AF100, 105, 106, 108, 109, 112, 115, and 119 as P-322, the rest as P-322A. Engines listed as V-1710-F5L-F5R, the P-322 usually have engine serials mentioned, the P-322A do not. Most references call the Lightning I V1710 engines F5R, the mark II the C-15. AF105, 106 and 108 to Britain, the US reports exporting them in February 1942, Britain reports them arriving in March, the RAF says Taken On Charge at Speke 25 March 1942, all 3 later issued to USAAF. First Mustang export September 1941, first arrival in October 1941.

The 667 Lightning II became P-38F 43-2035 to 2184 and P-38G 43-2185 to 2558.

 

[Reluctant Poster]

How effective in the bomber killing business were the Gladiators, Defiants and fighter Blenheims in 1940?

Only the Defiant used the Merlin. I don't see the relevance of gladiators and Blenheims or are you proposing to use the freed up Mercurys in a single seat twin?

 

[tomo pauk]

Only the Defiant used the Merlin. I don't see the relevance of gladiators and Blenheims or are you proposing to use the freed up Mercurys in a single seat twin?

My point is that, in the RAF's inventory, there was a whole forest of dead wood deserving the axe. A high-performance defensive fighter armed with perhaps 12 .303s is far less deserving of a critique than the Defiant, Gladiator and fighter Blenheim - let's forget the bombers for now - that required resources to make, pilots and fuel to to fly without making a dent on LW during the BoB.

RAF was in much worse position with trained pilots than it was in fuel stocks in 1940.

 

[don4331]

P-322's intake is on top of the boom ahead of the wing leading edge. Air comes in and make a 90* down into the carb. All the intake plumbing for the turbo is simply left out; the outer leading edge can probably be simplified aka made lighter is it isn't being used as an intercooler (or turned into fuel tank to extend range).

P-322 to Lightning I is the same change as P-40B to D: i.e. change from Allison C to F engines. The problem with the "C" nose is it uses: a: an internally toothed gear for reduction box (needs custom machining equipment) and a huge plain bearing. With number of engines being ordered and power increases to the engine, it was more challenging to increase capacity than to change to the 2 externally toothed gears. So, Allison changed production to the F nose*. But the actual thrust line doesn't change that much (Curtis/Lockheed still probably need to manufacture new cowls).

Could the low supercharger ratios be part of the contract for the French i.e. They wanted engines to be able to run on 87 (or worse) fuel. Then Allison was just fulfilling the contract they had in hand. I know there is a lot of bad blood between Lockheed and British over what was ordered versus what was needed.

*It makes commonality with the Allison E series easier too. C nose engines drove the supercharger via a shaft from the reduction gear. But the P-39 doesn't have a reduction gear on the engine, adding the reduction gears - crankshaft and internally tooth gear to drive the supercharger are expensive solution. Taking the drive off the back end of the crankshaft for the supercharger is a common solution.

The ~200 Merlins lost in Summer '40 when RR workers went on strike in middle of BoB would have powered 100+ Lightning Is... (You can see the dip in numbers G Geoffrey Sinclair provides). But there was no better time to get concessions from gov't for better housing, etc.

 

[Reluctant Poster]

My point is that, in the RAF's inventory, there was a whole forest of dead wood deserving the axe. A high-performance defensive fighter armed with perhaps 12 .303s is far less deserving of a critique than the Defiant, Gladiator and fighter Blenheim - let's forget the bombers for now - that required resources to make, pilots and fuel to to fly without making a dent on LW during the BoB.

RAF was in much worse position with trained pilots than it was in fuel stocks in 1940.

All airforces had deadwood. It's a fact that you can't replace your entire inventory at once. The USAAF still had P-26s based at Pearl Harbor on Dec 7 1941.

 

[Reluctant Poster]

P-322's intake is on top of the boom ahead of the wing leading edge. Air comes in and make a 90* down into the carb. All the intake plumbing for the turbo is simply left out; the outer leading edge can probably be simplified aka made lighter is it isn't being used as an intercooler (or turned into fuel tank to extend range).
View attachment 797377
P-322 to Lightning I is the same change as P-40B to D: i.e. change from Allison C to F engines. The problem with the "C" nose is it uses: a: an internally toothed gear for reduction box (needs custom machining equipment) and a huge plain bearing. With number of engines being ordered and power increases to the engine, it was more challenging to increase capacity than to change to the 2 externally toothed gears. So, Allison changed production to the F nose*. But the actual thrust line doesn't change that much (Curtis/Lockheed still probably need to manufacture new cowls).

Could the low supercharger ratios be part of the contract for the French i.e. They wanted engines to be able to run on 87 (or worse) fuel. Then Allison was just fulfilling the contract they had in hand. I know there is a lot of bad blood between Lockheed and British over what was ordered versus what was needed.

*It makes commonality with the Allison E series easier too. C nose engines drove the supercharger via a shaft from the reduction gear. But the P-39 doesn't have a reduction gear on the engine, adding the reduction gears - crankshaft and internally tooth gear to drive the supercharger are expensive solution. Taking the drive off the back end of the crankshaft for the supercharger is a common solution.

The ~200 Merlins lost in Summer '40 when RR workers went on strike in middle of BoB would have powered 100+ Lightning Is... (You can see the dip in numbers G Geoffrey Sinclair provides). But there was no better time to get concessions from gov't for better housing, etc.

What strike was that. The only one I am aware of is at Hillington in 1943