Aircraft Modifications

Hey lightning guy, what a p-49?

RG_Lunatic said:

mosquitoman said:

IMO the RAF heavy bombers needed an ventral turret so I would have put them on Lancasters, Halifaxes and Stirlings. It would have prevented a lot of german nightfighter kills as the Schrage Musik cannons were fitted to fire upwards into a bomber

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Some Lanc's did have a ventral turret or gun position, but for some reason this was not felt worth the weight, crewman, or obstruction of the bombay in most Lancasters.

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whilst it would have been usefull, it prevented the use of H2S, was very heavy, not much ammo and generally not worth it, due to lack of time i haven't given many reasons but i can give more when i have more time....................

My second mod would be a p-39 with a supercharged Allison. I would lengthen the fulselage fore and aft the cockpit to make room for more .50 ammo and the supercharger. The intercooler would be mouted on the side (like on the experimental model). I would mount a laminar flow wing with clipped tips,and put two or four.50's within the wing structure. I would replace the 37mm with a 20mm cannon.

The P-49 was a development of the P-38 with a pressurised cockpit and utilizing expiremental XIV-1430 engine. The engines were crap so the project never went anywhere.

Fitting Griffons wouldn't have been that much trouble. It was not that much bigger that the Merlin and the Allison was a little bigger than the Merlin as well. It certainly would have been no more trouble than the swap made for the Spit.

R-2800s would have killed the range of the P-38 since it guzzled fuel at a far greater rate that an inline engine.

One other modification I forgot to mention. I would get rid of the stupid elevator balances since they didn't do anything other that kill a few pilots trying to bail out.

Ive seen some papers before that showed where a B-29 or two was tested with water methanol injection. It safely gave each engine around 400~600 more horsepower. Each R3350 had a port for it on the carburetor or throttle body for fuel injected engines. According to the documents I read the reason the ADI wasnt added was 1. for cost and 2. the War Emergency setting gave around that much power already, especially with the fuel injected versions. Of course they sortof overlooked the fact that the WE setting was not a great idea during takeoff whereas the ADI would have cooled the engine plus add the needed power.

Lightning Guy said:

The P-49 was a development of the P-38 with a pressurised cockpit and utilizing expiremental XIV-1430 engine. The engines were crap so the project never went anywhere.

Fitting Griffons wouldn't have been that much trouble. It was not that much bigger that the Merlin and the Allison was a little bigger than the Merlin as well. It certainly would have been no more trouble than the swap made for the Spit.

R-2800s would have killed the range of the P-38 since it guzzled fuel at a far greater rate that an inline engine.

One other modification I forgot to mention. I would get rid of the stupid elevator balances since they didn't do anything other that kill a few pilots trying to bail out.

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Griffons were bigger and heavier than Merlins/Allisons. The Allison weighed 1345 lbs (1 stage supercharger, 1710 ci), the Merlin weighed 1690 lbs (2 stage supercharger, 1647 ci), and the Griffon weighed 1980 lbs (2 stage supercharger, 2240 ci) and the R-2800 weighed 2350 lbs (2 stage supercharger, 2800 ci). By the time you figure in the weight of the coolant, the R2800 and Griffon probably weigh about the same. The Allison on the other hand was quite a bit lighter than even the 2-stage Merlin, and the Allisons turbocharger unit could be placed well back of the engine, which was not possible with the supercharger. So balance is a real issue even when considering a Merlin, let alone a Griffon.

1980 lbs in a near the front of the boom is a lot more than 1345 lbs at the front of the boom and a turbocharger in the middle, and of course the radiators would have to be made larger and more coolant would need to be carried. The booms would have to be significantly lengthened, and this would mean they'd need to be a lot heavier. With the R2800, the package was very stout, so less modification would probably be needed, as the props would sit nearer and probably below the wing a tad (like on the Tigercat), but again the booms and other structures would have to be beefed up to support the weight.

And Griffon's didn't get great fuel economy either. It's not that radials didn't get as good of fuel economy as inlines, it is that they were bigger. Bore and stroke of the Griffon was 6 inches x 6.6 inches, where for the R2800 it was 5.8 inches x 6 inches, so we'd actually expect the R2800 to get better fuel economy per cylinder than the Griffon (of course, it had half again as many cylinders). There was a fuel charge burn efficiency issue with large cylinders and the R2800 was a little past the threshold, the Griffon moreso.

But really I think it is inapporpriate to consider taking an engine from another country for such a "mod". The Griffon simply was not available for the P-38. Also, there were no reverse direction Griffons available even in England (maybe this could be handled through gearing? But if so, why was it not done on the P-38 to start with?).

I think for this topic to be legitimately considered, we have to limit ourselves to technology and parts that were available to the country in question at the time.

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Lunatic

Why not take the Alisons from the P-82 then?

My problem with the R-2800 (in a P-38) is that this would require a MAJOr redesign to the booms (it's 4ft wide remember). Also, range would drop considerably and there really wasn't anywhere to put extra fuel in a P-38.

Lightning Guy said:

Why not take the Alisons from the P-82 then?

My problem with the R-2800 (in a P-38) is that this would require a MAJOr redesign to the booms (it's 4ft wide remember). Also, range would drop considerably and there really wasn't anywhere to put extra fuel in a P-38.

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I agree the R-2800 would be inpractical. I just think the Griffon would be as well. I don't see anything wrong with the Allison, with the K type prop the plane had plenty of usable power.

There would be plenty of room in the wings for more fuel according to my suggested re-design. The wings would probably be kinda like the P-47N wings, perhaps with the max chord a tad more forward of center (making it more traditional but still somewhat laminar flow), so there would be much more room outside the engines than on the actual P-38 wings. There would also possibly be some space for fuel behind the cockpit (which is moved forward), and the fuselage section could maybe even be extended back a tad as the tail fin is high so turbulence does not have to settle out between the back of the fuselage and the front of the tail plane.

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Lunatic

I think that would start running into problems with weight. And all the extra weight ourboard the engines would do nothing for maneuverability. All in all, it's starting to look nothing like a P-38.

If you want to add fuel, I think a better option would be to add fuel in the enlarged center wing section from the Swordfish. Being closer to the rotational axis there would be less effect on roll rate.

RG_Lunatic said:

I don't see anything wrong with the Allison, with the K type prop the plane had plenty of usable power.

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Exactly! The Allison combination used in the P-38 is pretty dang good as it is. Its got turbos feeding the single stage supercharger. In my opinion thats better than the 2 speed 2 stage Merlin. Many are so enthused by the Merlin because thats what powered most P-51's and just assume that Merlin is Gods gift to engine! But they fail to account the induction arrangement and exactly WHY most Allisons performed the way they did and WHY most Merlins performed the way they did. They just flat out discount the Allison and can not explain WHY!

LG I know you understand this and I dont mean it as anything personal at all, I just see this a lot in other places and with people and had to get it off my chest!

I don't take it as anything personal and I agree with everything you've said. When Lockheed ran the numbers of a Merlin powered Lightning the numbers were not really any different. The only real advantage I think the Merlin would have offered is a better reliability earlier in the war.

Lightning Guy said:

I think that would start running into problems with weight. And all the extra weight ourboard the engines would do nothing for maneuverability. All in all, it's starting to look nothing like a P-38.

If you want to add fuel, I think a better option would be to add fuel in the enlarged center wing section from the Swordfish. Being closer to the rotational axis there would be less effect on roll rate.

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Wings don't weigh that much, especially outside the landing gear. Added wing area would improve turn and climb rates, and it was clearly shown that properly designed wings that are not too long can be rather broad without harming manuverability. Rate of roll is more dependant on wing length than broadness. The main thing I'd change would be the sharp angle of rear of the wing, I'd make it more P-51 or P-47N like. Weight increases would mainly occur while there was fuel in the outer cells, which need not all be filled. P-47N's rolled very well, on a par with P-38L's.

And I agree, it might be a better idea to simply put the fuel behind the pilot and ammo store in the fuselage section, or make the fuselage section or booms a little taller to accomodate it. A taller fuselage center section with flat sides might improve lateral stability and make the P-38 a better gun platform.

I agree with all the changes I suggested it would not look that much like the P-38 we know - but each change is relatively minor from an engineering point of view, and the plane would actually be easier to construct.

The biggest change would be the gun package. What do you think about that? 2 x 20mm's with 250+ rpg, 5 x .50's with 400+ rpg. That's a lot of firepower!

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Lunatic

That wouldnt be bad!

RG_Lunatic said:

Some Lanc's did have a ventral turret or gun position, but for some reason this was not felt worth the weight, crewman, or obstruction of the bombay in most Lancasters.

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As well, the position where the turret was is where the H2S went. With the long bomb bay this is the only place it could go. When the Lancs started doing day bombing, the H2S was not needed and the belly gun position was re-installed.

There was a 'movement' to fit the P-38 with Merlins but lobbying by GM (Allison was a sub of GM) had it squashed.

The Allisons were more reliable than the early Merlins.


What I would do would be to give the Lanc a few more feet greater wingspan but would rather see the Halli replace the Lanc.

Anyone know why the Allison V-3420 when fitted to the B-29 (YB-39), even though gave the a/c better performance, were not used?

What I would do would be to give the Lanc a few more feet greater wingspan but would rather see the Halli replace the Lanc.

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Me too! And in turn see the Stirling replace the Halifax. Fwaha!

KraziKanuK said:

RG_Lunatic said:

Some Lanc's did have a ventral turret or gun position, but for some reason this was not felt worth the weight, crewman, or obstruction of the bombay in most Lancasters.

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As well, the position where the turret was is where the H2S went. With the long bomb bay this is the only place it could go. When the Lancs started doing day bombing, the H2S was not needed and the belly gun position was re-installed.

There was a 'movement' to fit the P-38 with Merlins but lobbying by GM (Allison was a sub of GM) had it squashed.

The Allisons were more reliable than the early Merlins.

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And if you look at it there is really no advantage. The Merlin's with a single stage supercharger produce no more power than the equivalent Allision, and they run much rougher, and weigh about the same. And there were no production lines to produce a Merlin running the opposite direction.

The big advantage to the Merlin was its integral supercharger stage, which the Allison lacked. One could have been built for the Allison but the choice was to instead setup a Packard plant to produce Merlins, mostly so these could be supplied to the Brits to power Spitfires and Lancasters in addition to their use in the P-51. If this had not been done, the Continental Hyper-engine would probably have been produced, and it would have made even more power than either the Merlin or the Allison. The Hyper-engine was a "hemi" head design, and was ready to go but was not built because there was not sufficient tooling capacity to build both it and the Merlin.

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Lunatic

cheddar cheese said:

Me too! And in turn see the Stirling replace the Halifax. Fwaha!

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I would not go that far Cheddar.

There was lots of bugs to be worked out of the Continental IV-1430. It never produced the power it was theoretically capable of. The Army did not help either.

how would you modify the stirling?? becauce it would need major mods if it was to replace the lanc and halibag.............

KraziKanuK said:

There was lots of bugs to be worked out of the Continental IV-1430. It never produced the power it was theoretically capable of. The Army did not help either.

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It was producing 1600 HP with a single stage supercharger, which is exactly what it was supposed to produce. All the "bugs" were worked ut by 1939. The problem with the XP-58 project was the result of continually changing Army specifications, which required increasingly larger engines for a increasingly heavy plane.

The IV-1430 was actually slated for production. When they decided to produce the Merlin, the Packard plant was already in the process of gearing up for the Continental engine, and was diverted to produce the Merlin instead.

It was a much more compact inverted V design than the Merlin or Allison, and it was also designed in such a way that it would be more damage resistant. On the otherhand, it was relatively heavy for its size because of this.

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Lunatic