# Aircraft Modifications



## The Jug Rules! (Jan 26, 2005)

If you could modify any aircraft from ww2(guns,engines, etc.) what would you do??


----------



## the lancaster kicks ass (Jan 26, 2005)

an 8 engined lancaster zwilling style bi-plane...................


----------



## The Jug Rules! (Jan 26, 2005)

The lank already had enough engines already!!!


----------



## the lancaster kicks ass (Jan 26, 2005)

yes but when i've got two lenghtend fusilages and a bi-plane wingspan of well over 150ft, i'll need atleast 4 more..............


----------



## DaveB.inVa (Jan 26, 2005)

How bout getting the Lanc a second pilots station while your at it.


----------



## DaveB.inVa (Jan 26, 2005)

I wouldve gave most WWII bombers and fighters water/methanol injection. Fighters did use it quite a bit for extra power in a dogfight but the bombers could've used it to allow more power during takeoff. Almost all sides sent their bombers off with as much bombs and fuel as they could (adjusting accordingly for range to target) and Im sure the extra power for takeoff would've been appreciated. 

For the B-29 I've saw pictures of a couple versions with a probe extending forward of the cockpit for aerial drogue refuelling. That would've been nice. It would've been hard to refuel as many aircraft as were normally sent on a large mission, but perhaps have a couple squadrons equipped so they could really reach out there. The crew of Bockscar would have appreciated that on the Nagasaki mission as well.


----------



## the lancaster kicks ass (Jan 26, 2005)

DaveB.inVa said:


> How bout getting the Lanc a second pilots station while your at it.



why?? the lanc's pilot often trained his flight engineer to hold the craft straight and level so the crew could bail out if the pilot was incapacitated..................


----------



## DaveB.inVa (Jan 26, 2005)

Yeah, but had they're been a second pilot aboard then he could've quite possibly brought the aircraft back to friendly territory. The crew wouldnt have became POW's and you probably could get the pilot some medical attention. They might have even been able to save the entire aircraft! Pretty big gamble to me just having one dude in the whole aircraft thats properly trained to fly.

Asking why to that question is like refusing a surgeon just because moms at home and handy with the knife!


----------



## the lancaster kicks ass (Jan 26, 2005)

dude this is my modification, i don't want a second pilot's posistion and no-one will make me change my mind....................


----------



## DaveB.inVa (Jan 26, 2005)

Never was forcing you to do it. Just a suggestion... perhaps another flight engineer or so to take care of all those powerplants then?


----------



## mosquitoman (Jan 26, 2005)

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


----------



## the lancaster kicks ass (Jan 26, 2005)

stop messing with my mod!!!!


----------



## mosquitoman (Jan 26, 2005)

I'm not, that was my mod


----------



## The Jug Rules! (Jan 26, 2005)

You guys can use experimental aircraft too.  

I would have given the p-38 Packard Merlins with 4 blade Hamilton standards, and as many 20mm cannons as I could cram in the nose.


----------



## Lightning Guy (Jan 26, 2005)

The problem with cramming 20mms in the nose of a P-38 is that you run out of room for ammo. Lockheed did design an installation to fir 4 20mm cannons into the nose of a P-38 but the firing time was down to a mere 5 seconds.


----------



## Lightning Guy (Jan 26, 2005)

Ok. I gave this some thought.

Of course I would modify a P-38. In the first place I would replace the V-1710s with Griffons (the airframe could have handled the extra power and the engines were nearly identical in size). Since the Griffons had their own mechanical supercharges I would remove the B-33 turbos making room in the booms for a water-methanol injection system and a second generator. I also would have fitted the engines with exhaust shrouds to provide some residual thrust. Finally (to the engines anyway) I would have fitted the HS paddle-blade props.

The airframe I would modify along the lines of the 'Swordfish' P-38 to delay the onset of compressibility and improve diving speed.

Finally, I would have adopted the 2 20mm cannon and 4 .50cal armament that Lockheed was intending to fit to the P-49.


----------



## Anonymous (Jan 27, 2005)

DaveB.inVa said:


> I wouldve gave most WWII bombers and fighters water/methanol injection. Fighters did use it quite a bit for extra power in a dogfight but the bombers could've used it to allow more power during takeoff. Almost all sides sent their bombers off with as much bombs and fuel as they could (adjusting accordingly for range to target) and Im sure the extra power for takeoff would've been appreciated.
> 
> For the B-29 I've saw pictures of a couple versions with a probe extending forward of the cockpit for aerial drogue refuelling. That would've been nice. It would've been hard to refuel as many aircraft as were normally sent on a large mission, but perhaps have a couple squadrons equipped so they could really reach out there. The crew of Bockscar would have appreciated that on the Nagasaki mission as well.



Many bombers did have ADI (water/methenol injection - though the Allies used a higher ratio of water to methenol than the Germans). It is listed as ADI if its listed, but it was not critical for anything but takeoff, as most bombers didn't use "WEP" for combat. Check out the B-26 and A-26 in particular (the A-26 did use it for "combat power").

By late in the war almost German/British/American fighters had water injection. The most notable exception is the P-51. It didn't have any overheating issues and the radiator thrust system worked best if the engine were running at full temp, so it was not felt to be useful.

=S=

Lunatic


----------



## Anonymous (Jan 27, 2005)

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



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.


----------



## Anonymous (Jan 27, 2005)

Lightning Guy said:


> Ok. I gave this some thought.
> 
> Of course I would modify a P-38. In the first place I would replace the V-1710s with Griffons (the airframe could have handled the extra power and the engines were nearly identical in size). Since the Griffons had their own mechanical supercharges I would remove the B-33 turbos making room in the booms for a water-methanol injection system and a second generator. I also would have fitted the engines with exhaust shrouds to provide some residual thrust. Finally (to the engines anyway) I would have fitted the HS paddle-blade props.
> 
> ...



This is the plane I'd change too.

Merlins (as suggested by Jug) would not have done much for the P-38, the turbo-supercharged Allisions were every bit as good.

I don't think the Griffon would be an option without a very major redesign, as they are considerably bigger and heavier than the Allisons and require much bigger radiators. Late model P-38's had ADI (water injection). And you still need to mount one stage of the supercharger externally. If you're going to go that far, why not put R-2800's on it and get even more usuable power for less weight and avoid the cooling problems? Also, there was no US source for the Griffon and British supplies were fully utilized by the Brits.

I'd have made the following changes to the P-38 (assuming no technology transfers from any other country are possible).

1) Use a more conventional wing design, or a laminar flow type wing. Use squared off wingtips to ease production. Increase the fuel load in the outboard wing panels using the added space.

2) Put the 3 bladed paddle props ala the P-38K on the production model. (or maybe 4 bladed - not sure of the issues).

3) Subject to wind tunnel tests... extend the tail fins higher and raise the stabilizer fin to the top of the tail fins to avoid turbulence comming off the fuselage and/or wings and improve leverage. Kind of like on the North American OV-10 Bronco FAC/Counter-insurgency plane.

4) Redesign the canopy with a bubble top and move the cockpit forward a bit. Angle the front down some so the pilots downward view is improved.

5) Put at least a 4 mm armor plate over the top turbine containers and fuel feeds to the engines. Alternatively, install some kind of fire extinquisher system.

6) Remove the 20mm from the nose and replace it with a .50 BMG.

7) Install two 20mm's, one in each wing root, inside the propeller arc with 250 rpg (or more) with the ammo feeding from the fuselage using power assisted feeds. Stagger the left and right guns slightly to maximise ammo loads. (Remember the pilot is sitting more forward so there's pleanty of room).

=S=

Lunatic


----------



## cheddar cheese (Jan 27, 2005)

Ok, heres what id do.

Take a P.108A and replace its 1350hp Piaggio engines with Griffons. I would then add a an anxillary jet engine to each side, B-36 style. I would lengthen the wingspan in an effort to increase altitude and also add a fuselage section from a P.108C (as it was bigger) therefore it would be able to carry more bombs 8)


----------



## The Jug Rules! (Jan 27, 2005)

Hey lightning guy, what a p-49?


----------



## the lancaster kicks ass (Jan 27, 2005)

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
> ...



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....................


----------



## The Jug Rules! (Jan 27, 2005)

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.


----------



## Lightning Guy (Jan 27, 2005)

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.


----------



## DaveB.inVa (Jan 27, 2005)

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.


----------



## Anonymous (Jan 27, 2005)

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.
> 
> ...



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.

=S=

Lunatic


----------



## Lightning Guy (Jan 27, 2005)

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.


----------



## Anonymous (Jan 27, 2005)

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.



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.

=S=

Lunatic


----------



## Lightning Guy (Jan 27, 2005)

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.


----------



## DaveB.inVa (Jan 27, 2005)

RG_Lunatic said:


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



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!


----------



## Lightning Guy (Jan 28, 2005)

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.


----------



## Anonymous (Jan 28, 2005)

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.



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!

=S=

Lunatic


----------



## cheddar cheese (Jan 28, 2005)

That wouldnt be bad!


----------



## KraziKanuK (Jan 28, 2005)

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.



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?


----------



## cheddar cheese (Jan 28, 2005)

> 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.



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


----------



## Anonymous (Jan 28, 2005)

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.
> ...



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.

=S=

Lunatic


----------



## KraziKanuK (Jan 28, 2005)

cheddar cheese said:


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



I would not go that far Cheddar.


----------



## KraziKanuK (Jan 28, 2005)

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.


----------



## the lancaster kicks ass (Jan 28, 2005)

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


----------



## Anonymous (Jan 28, 2005)

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.



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.

=S=

Lunatic


----------



## KraziKanuK (Jan 28, 2005)

_However, the first flight was delayed by problems with the experimental Continental engines, which were not yet cleared for flight operations at the time they were delivered to Lockheed in April 1942. It was not until November 14, 1942 that the XP-49 took to the air for the first time, flown by test pilot Joe Towle.

The aircraft was grounded only a week later for replacement of the engines by XIV-1430-13/15 engines_

_The initial flight tests of the XP-67 were delayed by fires in BOTH engines that broke out during a high-speed taxiing run at Lambert Field in St Louis on December 8, 1943. After being repaired, the XP-67 was trucked to Scott Field in Illinois. The first flight of the XP-67 took place there on *January 6, 1944* with test pilot E. E. Elliott at the controls. However, this flight had to be abruptly terminated after only six minutes owing to engine problems._

_This accident, plus the seemingly endless series of problems caused by the temperamental Continental engines, caused the USAAF to recommend that work on the XP-67 project be halted._

Estimated power of the IV-1430 in the P-67 was *1060hp* from its hoped for 1350hp(G. White). The bugs were worked out? Does not look that way.

The Muskegon plant also built P&W R-1340s.


----------



## Anonymous (Jan 28, 2005)

KraziKanuK said:


> _However, the first flight was delayed by problems with the experimental Continental engines, which were not yet cleared for flight operations at the time they were delivered to Lockheed in April 1942. It was not until November 14, 1942 that the XP-49 took to the air for the first time, flown by test pilot Joe Towle.
> 
> The aircraft was grounded only a week later for replacement of the engines by XIV-1430-13/15 engines_
> 
> ...



I've never seen that info. Perhaps you are right.

Only about 35 of the hyper-engines were built, none were "production" engines.


----------



## Lightning Guy (Jan 28, 2005)

And the 'hyper-engine' projects ate up countless valuable hours of manpower without producing a single, combat-capable engine. One of the great flops in the history of the American aviation history if you ask me.


----------



## Anonymous (Jan 28, 2005)

Lightning Guy said:


> And the 'hyper-engine' projects ate up countless valuable hours of manpower without producing a single, combat-capable engine. One of the great flops in the history of the American aviation history if you ask me.



Umm... it ate up relatively few hours, mostly prior to the war. There were lots of such projects on all sides. The Bristol Centaraus project comes to mind as one of the biggest failed engine projects of the war. Far far more resources were spent on it than the hyper-engine, to produce a very few working bombers and left a few hundred Tempest II's sitting w/o a powerplant till after the war was over.

Had the hyper-engine recieved substantial attention, it probably would have worked fine. Instead, it recieved minimal focus, being relegated to a single rather minor project which was botched in many respects, not just the engine development.

=S=

Lunatic


----------



## Lightning Guy (Jan 28, 2005)

But the Centaraus did become a viable engine. And the Sea Fury with a Centaraus engine was one of the best piston-engined fighters of all time.


----------



## Anonymous (Jan 28, 2005)

Lightning Guy said:


> But the Centaraus did become a viable engine. And the Sea Fury with a Centaraus engine was one of the best piston-engined fighters of all time.



So would have the hyper engine, if the need to further develop inline aircraft engine had persisted. It did not, by the time the bugs were worked out of the Centaraus, the jet age had arrived. By the time the SeaFury was deployed, it was already totally out-of-date.


----------



## KraziKanuK (Jan 28, 2005)

Bristol did not have the engineering staff to properly develope the Centaurus. When Bristol's directors fired Roy Feldon in Oct 1942, the Centaurus engine took a big hit. Bristol did manage to poduce 2800 engines though befor wars end.

LightningGuy, the hypers were not a waste of time for much was learned from them.


----------



## Lightning Guy (Jan 28, 2005)

Maybe. But in time of war I feel your limited time and resources are better spent producing what works.


----------



## Anonymous (Jan 29, 2005)

Lightning Guy said:


> Maybe. But in time of war I feel your limited time and resources are better spent producing what works.



Well of course, but that is easy to say with 20:20 hindsight. All sides spent significant resources working on projects that did not work.


----------



## Anonymous (Jan 29, 2005)

KraziKanuK said:


> Bristol did not have the engineering staff to properly develope the Centaurus. When Bristol's directors fired Roy Feldon in Oct 1942, the Centaurus engine took a big hit. Bristol did manage to poduce 2800 engines though befor wars end.



The Centaraus engines were not really buildable until Bristol got a Thompson centerless grinder. I believe what happened was the required tolerance of 1/10000 of an inch for the sleeve valves was too tight for prior machine tools to properly fabricate. This resulted in very high oil consumption and poor cylinder unit durability until post war. The three of the Thompson centerless grinders provided to Britain during the war all went to the Napier Saber project. The Centaraurs engines that were produced were suitable only for bombers, such as the Warwick, which could carry a lot of oil. This is why several hundred completed Tempest II's, with installed Centaraus engines, were never deployed to combat units. They simply could not carry enough extra oil to make them safe for combat.

Do you mean Bristol engines including the Hercules? I only know of about 4-500 wartime Centaraurs engines.


----------



## DaveB.inVa (Jan 29, 2005)

KraziKanuK said:


> 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?



The XB-39 with the V-3420 wasnt produced mainly because most of the problems with the R-3350 had been worked out. 

The performance difference was only marginal. The V-3420 gave 3000 hp on takeoff but only had 2100 hp at 25,000 ft. It had an integral single stage single speed supercharger plus this was fed by a single turbocharger. The R-3350 on the other hand had an integral single stage single speed supercharger plus two turbochargers. This enabled the R-3350 to maintain its rated 2200 hp to around 30,000 ft. The R-3350 was also able to make some of its War Emergency power at this altitude as well. Later fuel injected R-3350's that employed newer turbochargers could certainly make more power at 30,000 ft plus. I have talked to many who have said late war R-3350's were underrated, meaning they were making more power than advertised. Some have said these late R-3350's in War Emergency power were making close to what later R-4360 made at takeoff. That equals out to around 3500 hp. I dont know whether thats true or not but I'll take their word on it, they were there!

The performance of the XB-39 was listed as 405 mph at 35,000 ft. This isnt exactly comparing apples to apples though. The XB-39 was converted from the first YB-29. Even though it was equipped with full armament it can be safe to say that this aircraft didnt weigh nearly as much as a like armed B-29 in the Pacific. It almost certainly didnt have a lot of the armor plating, electronics, radar and some safety equipment that a standard B-29 would carry. 

Another thing that should be considered is the propellers. The XB-39 was equipped with Curtiss Electric units that have a broader chord than the Hamilton Standard units found on most B-29s. This can be compared to the performance increase at altitude found between the B-17E and B-17F due to the paddle blade propellers. The F was heavier yet at the same power rating had a higher service ceiling and was faster at its ceiling.

A truer comparison perhaps would be to compare the XB-39 to the Silverplate B-29's of the 509th Composite Group. The Silverplates were stripped of turrets but did carry a full suite of electronics, radar and safety equipment. Silverplates also were equipped with the latest fuel injected R-3350's turning broader chord Curtiss Electric reversible pitch propellers. These were truly the finest B-29's that could be found in the Pacific. They were able to climb higher and fly faster than standard B-29's. During the Nagasaki mission at one time Bockscar flew over 39,000 ft fully loaded. In talking with 509th veterans, a few pilots, flight engineers and a couple NCO's, they have said during their practice pumpkin missions that coming out of their steep turn and running away that they frequently got over 400 mph. The aircraft at the time would have been unloaded and in its already light condition plus the Curtiss Electric props and being at War Emergency power I see this as being extremely possible. Like before, they were there!


----------



## HealzDevo (Feb 3, 2005)

A B-36 Peacemaker with extra guns and extra power, and depending on when we are talking about anti-aircraft missiles and cluster-bombs. That would really have an impact on an opposition pilot, something like that.


----------



## Anonymous (Feb 3, 2005)

The B-36 is clearly a post WWII design. I think this topic is restricted to WWII technology and planes.

(note: edited "P-36" to "B-36")


----------



## wmaxt (Feb 4, 2005)

RG_Lunatic said:


> The B-36 is clearly a post WWII design. I think this topic is restricted to WWII technology and planes.
> 
> (note: edited "P-36" to "B-36")



I'll try to find the reference but the B-36 design was begun in WWII. The fear was that bombing missions may have to be based on the East Coast of the US. The B-36 was to make that not only possible but more or less practicle.


----------



## DaveB.inVa (Feb 4, 2005)

Requests for preliminary designs for a bomber capable of 450mph top speed, 275mph cruise, 45000' ceiling, and max range of 12000 miles at 25000' carrying 10000lbs were issued to Boeing and Consolidated on April 11, 1941. And on November 15, 1941 a contract was issued to Consolidated to provide two XB-36's.


----------



## the lancaster kicks ass (Feb 5, 2005)

but it was soon realised that we could hold Britian (you don't show much faith in us, do you??) and the B-36 wouldn't be needed really so it didn't become much of a priority.............


----------



## HealzDevo (Mar 19, 2007)

A B-17 with side firing heavy gun plus a couple of light machine guns for close combat support like the AC-130 Hercules does for US troops today. Would have helped at Tarawa, Omaha, Iwo Jima and a few other places by acting as aerial artillery against bunkers and things...


----------



## FLYBOYJ (Mar 19, 2007)

HealzDevo said:


> A B-17 with side firing heavy gun plus a couple of light machine guns for close combat support like the AC-130 Hercules does for US troops today. Would have helped at Tarawa, Omaha, Iwo Jima and a few other places by acting as aerial artillery against bunkers and things...


It wouldn't of worked - they had no accurate way to target it.


----------



## Civettone (Mar 19, 2007)

What aiming devices did the succesful AC-47 have?



Kris


----------



## DerAdlerIstGelandet (Mar 19, 2007)

Also I dont think the aircraft would have been wide eneogh to incorporate the larger guns. I may be wrong though.


----------



## DerAdlerIstGelandet (Mar 19, 2007)

Civettone said:


> What aiming devices did the succesful AC-47 have?
> 
> 
> 
> Kris



AC-47s were not used in WW2. They were introduced in Vietnam in 1964 with the 4th Air Commando. By the end of 1965 there were 26 in service.

I however do not know how they were aimed the guns at a specific target. I know at first it was used with a crude grease pencile target thing, but later on I am sure electronic devices were used. Not sure though.


----------



## FLYBOYJ (Mar 19, 2007)

Civettone said:


> What aiming devices did the succesful AC-47 have?
> 
> 
> 
> Kris




They had optical sights but were not as accurate as what we have today. The first AC-47s and AC-119s used "minnie guns" and just peppered the directed targets. When the AC-130s were introduced we started to see side looking radar, IR targeting systes and other systems that not only allowed accurate targeting, but allowed the use of larger guns.

Chris has a point - I don't think the fuselages in the B-17 would of been wide enough.


----------



## HealzDevo (Mar 20, 2007)

Okay, perhaps. In the end it was just an idea sort of thing.


----------



## Civettone (Mar 20, 2007)

Well, if the AC-47 used optical sights then the "AB-17" would have been equally accurate. 

Besides, if you recall, there was a heavy escort fighter variant of the B-17. Most had lots of heavy MGs but some had 40mm guns.

Kris


----------



## HealzDevo (Mar 21, 2007)

Just a good question on why it was never tried in WW2 when they had Tarawa and that which could have been good for softening up by air...


----------



## DerAdlerIstGelandet (Mar 21, 2007)

They did not have weapons suitable for the task.


----------



## FLYBOYJ (Mar 21, 2007)

Civettone said:


> Well, if the AC-47 used optical sights then the "AB-17" would have been equally accurate.
> 
> Besides, if you recall, there was a heavy escort fighter variant of the B-17. Most had lots of heavy MGs but some had 40mm guns.
> 
> Kris




The AC-47 had a battery of mini guns that blanketed an area and was designed for air-to-ground counter-insurgency supression. The B-40 was designed as an escort gunship.






here's the gunsight...


----------



## Civettone (Mar 21, 2007)

I know that Flyboy. If there was already a B-17 like the later AC-47 we wouldn't be having this discussion, would we?

My point was that the "AB-17" would have been possible: take the guns from the YB-40 (put pointed downwards) and the gunsights of the later AC-47 and you'll have an "AB-17" armed with a whole array of guns capable of "blanketing an area".

Not saying they should have build it, only that it was possible.
Kris


----------



## renrich (Mar 21, 2007)

The YB-40 was not a successful concept because of CG problems and because unless they had fired off most of their ammunition they were too heavy to keep up with the bombers on the way home. I don't believe any models of the B-17 ever carried any 40 mm guns.


----------



## MacArther (Mar 21, 2007)

Where to start.......

1. Produce the P40-Q, but forgo the six .50 cals in the wings and install four 20mm's instead. Give it plumbing for drop tanks, as well as some support for carrying around 1500 lbs of bombs/underslung ordinance max.

2. Give the Hurricane late models (from about IID to IV) a better engine, say one designed to give a better top speed than the ones that were used. Fix the 40mm S guns to planes on tank hunts via blow-away bolts, so the guns can be dropped in flight if need be. Finally, on the mentioned late marks, give the fighter a little more than the two .303 guns that were fitted besides the modular armament. It could be two more guns with less ammo, or it could just be two .50 cals, I just think that the planes should have more firepower for strafing on infantry and self defense if jumped by fighters.

More to come, just can't remember what I was about to write.


----------



## FLYBOYJ (Mar 21, 2007)

Civettone said:


> I know that Flyboy. If there was already a B-17 like the later AC-47 we wouldn't be having this discussion, would we?
> 
> My point was that the "AB-17" would have been possible: take the guns from the YB-40 (put pointed downwards) and the gunsights of the later AC-47 and you'll have an "AB-17" armed with a whole array of guns capable of "blanketing an area".
> 
> ...


With what guns? .50 cal? If we're talking about using a B-17 in a spooky role years later, sure - I don't think a YB-40 with all it's .50s pointed down would of been as effective. The thing that made the AC-47 was its guns.


----------



## DerAdlerIstGelandet (Mar 22, 2007)

Exactly and that is why I said there were no weapons suitable. You needed the mini guns man!


----------



## Civettone (Mar 22, 2007)

Aaah... I didn't know that the AC-47 used miniguns, I thought it used machineguns. Wiki just told me. My mistake! 

As miniguns weren't available in WW2, neither the AC-47 could have existed that soon. 

Kris


----------



## FLYBOYJ (Mar 22, 2007)

Civettone said:


> Aaah... I didn't know that the AC-47 used miniguns, I thought it used machineguns. Wiki just told me. My mistake!
> 
> As miniguns weren't available in WW2, neither the AC-47 could have existed that soon.
> 
> Kris




My brother was in Vietnam and witnessed AC-47 and AC-119 Spooky strikes. He said when they fired on a target everything within the blanket of the mini guns and .30 cals had lead through them. It was not uncommon to find 100 dead VCs or NVA regulars who were caught by one of these aircraft.


----------



## Matt308 (Mar 22, 2007)

I'm still struggling with Mac's suggestion of hanging 40mm cannon below a P-40 with explosive bolts so they could be dropped on a whim. 

I gotta give him credit...he's thinkin'.


----------



## DerAdlerIstGelandet (Mar 22, 2007)

I was fortunate to see the AC-130 unleash its might over Iraq during a mission. We were flying away off from the fight waiting for the call from the infantry to come back in and get them after they accomplished what they had to do and they called in for "Puff". Needless to say it was one of the most exciting things I have seen and also strangly beautiful.


----------



## MacArther (Mar 22, 2007)

> I'm still struggling with Mac's suggestion of hanging 40mm cannon below a P-40 with explosive bolts so they could be dropped on a whim.
> 
> I gotta give him credit...he's thinkin'.



Actually, the 40mm's attached by explosive bolts would be for the improved Hurricane IID-IV models.

And thanks, I rarely come up with something plausible or useful in relation to old style armament, planes, etc....


----------



## Grampa (Mar 25, 2007)

How whould you say if I whould make a plan to turn the de Havilland D.H98 Mosquito in to an divebomber. I whould basicly use the FB.Mk XVIII whit a modification by remove the 57-mm Molins antitankgun and replacing it whit the original 4x20mm cannon. and maby I also put a large bombdors in the fuselage same as the B.Mk XVI use so it could carry up to 1814-kg bombs if it goes well. Last and most importent thing I whould replace the original gunsight whit the m/42B bombsight instead. The m/42B whas probably the most eficient and advanced device for divebombing in WW2, it allovs the plane to divebomb to the target whit a angle low as to 30 degreed and it can also calculating the windspeed to make more accurate. That whould make no need of major reinforcement to the fuselage to handle the high G-force that comes when pulling out from the original divebombning that originality happens in 80-70 degrees or so, it whould also be no need for put in divebrake in the plane ether.


----------



## DerAdlerIstGelandet (Mar 25, 2007)

Just my opinion but turning the Mossie into a Dive Bomber would defeat the purpose of the beautiful bird.


----------



## Grampa (Mar 25, 2007)

Mr Adler. You dident thougt that my idea to this whas to make the beautyful plane more usefull in some other offensive ways. Even if the "mossie" could divebombnin whit those "mods" it still wouldent mean that the plane newer can be in the main roll as a fighterbomber whit no influence on the original performance. A Figherbombing "mossie" that can also divebomb on the target efficient as a original divebomber whas my idea.


----------



## DerAdlerIstGelandet (Mar 25, 2007)

If that would be possible, but I just dont see the need for a dive bombing mossie. She did just fine how she was concieved. Just my opinion again.


----------



## Glider (Mar 25, 2007)

I think I am right in aying that one was modified as a dive bomber but the ad a problem with the dive brakes as they had to be quite large and ruined its performance. Its a very slippery aircraft, gained speed quickly and was hard to low down.

This is I admit totally from memory but I recall a photo of one and the airbrakes were all around the fusalage like an umbrella. 

On bomber was also fitted with a gun turret but it also lost a lot of speed and range due to the drag.


----------



## Glider (Mar 25, 2007)

Have dug a bit more and it seems to have been a Youngman circular segmented air brake.


----------



## Sgt. Pappy (Mar 26, 2007)

glider! i see ur okay and kicking! lol i remember u once said u were ill.. good to see u back! 

anywho if i had to modify anything, i would have given the 109 slightly larger wing area - maybe 10% more. it turned pretty well and giving it more wing area would probably allow it to turn tighter. 

i would also have that 33 Imp. Gal. tank and the 41 imp. gal. tank installed in the rear way earlier than 1945 in the back of spitfire IX's, XVI'x and XIV's. Anyone know how heavy one of those self-sealing 33/41 imp. gal. tanks are when empty? b/c if it was too heavy it would probably have affected maneuevrability.


----------



## Grampa (Mar 27, 2007)

If you whas a pilot of a "Mossie" and making a havoc on the german train, truck, tanks, briges and other small target, dosent it annoying you that there a great possible that you can miss the target, then whouldent you have something that help you redusing the possible of missing the target, speciallity when the target is protected whit flak and you dont whanna do another bombrun if you missed it. The more "mossie" hit the target whit more precision the less cost of planes, bombs and pilots it gonna be and the war gonna be shorter. Some of you who read this and playing some sort of combat flight simulator and doing fighterbombning, dont you often going in to the target in a like 30-40 degree dive more or less? dosent that tell you that the pilot of the "Mossie" must have done in a some sort of a low-degree divebombning whit it to? Like you doing in the same way in your simulator. Its is a perfect situation for using the M42/b bombsight for the "Mossie". the argument of not using the M42/B bombsight is like if I had a old WW1 gunsite on my WW2 fighterplane and someone says there no need for an replacement for the gunsight. well I whant a new one so I can be sure to hit the enemy fighterplane more often when i have it in my sight, otherwise he might gonna shoot me down if i miss him.


----------



## HaWk3r T3mP3sT (Mar 27, 2007)

Oh Guys (and ladies) i love the ideas you,ve come up with, but personally i believe mines the best.
I called it the Hawker Tempest mk7 its a standard Tempest mk6 but with another need for all u guys, a beer fridge!
What ya think?


----------



## Desert Fox (Mar 27, 2007)

I would choose the P-47, but with a larger airframe...its just a little too small 

Perhaps the Westland Whirlwind, but with Rolls Royce Merlin Engines, instead of those pesky Peregrine engines. I would have loved to have seen it in mass production...a rival for the Beaufighter perhaps?


----------



## DerAdlerIstGelandet (Mar 27, 2007)

HaWk3r T3mP3sT said:


> Oh Guys (and ladies) i love the ideas you,ve come up with, but personally i believe mines the best.
> I called it the Hawker Tempest mk7 its a standard Tempest mk6 but with another need for all u guys, a beer fridge!
> What ya think?



24 hours from the bottle to the throttle...


----------



## Gnomey (Mar 27, 2007)

DerAdlerIstGelandet said:


> 24 hours from the bottle to the throttle...


Yep...


----------



## Procrastintor (May 31, 2013)

I know this is an old thread but I'm bringin' it back. I'd grab a P-40E and put a Merlin engine in, and put two more .50's in the nose like the P-40C. I'd also make a tank buster variant like the Stuka and but a 37mm under the fuselage


----------



## Aozora (May 31, 2013)

Procrastintor said:


> I know this is an old thread but I'm bringin' it back. I'd grab a P-40E and put a Merlin engine in, and put two more .50's in the nose like the P-40C. I'd also make a tank buster variant like the Stuka and but a 37mm under the fuselage



Don't forget the interrupter gear lest that li'l ol' 37mm accidentally shoots off the li'l ol' propeller...


----------



## Shortround6 (May 31, 2013)

P-40Fs and Ls already had Merlins. 

Difference between a P-40C and a P-40E or F was a change in reduction gear that raised the propeller 6 inches making fitting the cowl .50s a tight squeeze. The Later P-40s also used the space from the guns and ammo to move the oil tank to. The >50 cal did NOT take well to synchronizing with many installations firing at less than 500rpm compared to the 800rpm for the wing guns. 

Blowing your own prop off is not going to impress the enemy tankers. NOBODY got a gun over 23mm into service in a synchronized installation. Some gun mechanisms are impossible to synchronize and other mechanisms, while suitable from mechanical stand point, fall down with large caliber shells. The large shells have a more variable burn time from primer initiation to shell exiting the muzzle. 
The P-40C had 9 prop blades pass in front of the cowl .50s for each time the guns fired (if they made 500rpm). You don't have a lot of time to fool around with for variations in charge burn. Nicking your prop with .50 is one thing, hitting it with a 37mm is another.


----------



## wuzak (May 31, 2013)

Wasn't the 37mm considered a poor air to air weapon?

And had a low muzzle velocity?

So, if you could synchronise it, the low muzzle velocity and the size of the round would make the timing interesting.


----------



## Procrastintor (May 31, 2013)

Well wouldn't two more .50s be useful even at a slower RPM? And as for the 37mm, would it be better in underwing pods like un the JU-87?


----------



## altsym (May 31, 2013)

I believe the P-40D experimented with 2x 20mm Hispano-Suiza in gun pods slung under the wings. IIRC, it was a failure.
The E,F,K,L,M,&N versions retained the mounted point under the skin however.

@ Procrastintor, interesting the drop tank on your signature P-40N is backwards. IF they really did that, the blunted end
facing backwards would create an area of low pressure, and create more drag.


----------



## Procrastintor (May 31, 2013)

I know they did the drop tank thing on real ones in Burma, don't know why though. And thanks for the info on the P-40D, I never knew they tried that.


----------



## Shortround6 (May 31, 2013)

Procrastintor said:


> Well wouldn't two more .50s be useful even at a slower RPM? And as for the 37mm, would it be better in underwing pods like un the JU-87?



The P-40E and later versions were already carrying too much armament for the engines, adding cowl guns just makes it worse. You can lug all the guns you want but if you can't put them on target they are useless. 

A P-40C was carrying 230 KG of guns and ammo but not including gun mounts, ammo boxes/chutes, gun heaters, solenoids, etc. A P-40E went to 332KG of guns and ammo without "accessories" with very little increase in power. 

Sticking a pair of .50s in the cowl with just 200rpg is going to add 112kg without the "accessories". 

Attempts to improve combat performance of the P-40 included pulling a .50 cal from each wing and limiting the remaining guns to 201 rounds apiece, pulling the electric starter and using a smaller battery, taking out one fuel tank, Using magnesium wheels and aluminium radiator and oil cooler cores. 

The P-40 was under powered/over weight for most of it's career. Stuffing in more guns just makes it worse. 

You better have good fighters flying escort for you if you try and use this for ground attack.


----------



## Procrastintor (May 31, 2013)

I see, I never thought about that, thanks!


----------



## merlin (Jun 2, 2013)

With the Wellington version optimised for torpedo dropping i.e. 2 18" - replace the bomb aimer's position with the 37mm COW cannon (which later became the Vickers 'S), - it would certainly put the aim off any target ship's flak guns!!


----------



## MacArther (Jun 3, 2013)

merlin said:


> With the Wellington version optimised for torpedo dropping i.e. 2 18" - replace the bomb aimer's position with the 37mm COW cannon (which later became the Vickers 'S), - it would certainly put the aim off any target ship's flak guns!!


I like the idea, but you might need that position on a plane that big to help drop the torpedo's. Also, I don't know if structural integrity could support such a gun at the front, but more knowledgeable people would have to comment on that.


----------



## Shortround6 (Jun 3, 2013)

You might be able to fit it in but the 37mm COW cannon (which did NOT become the Vickers' S without a LOT of development/modification) wasn't that _HOT_ of a cannon. 

It used a lighter shell at a lower muzzle velocity than the "S" for about 60% of the muzzle energy of the S (depending on ammo) and fired slower, not that the S was any great shakes in the rate of fire area to begin with. The COW was feed with 5 round clips which _might_ have been extended. 

Video of a COW firing: skip to 0.46 if you want. 

[video]http://video.search.yahoo.com/video/play;_ylt=A2KLqIDB1KxReBgAUPH7w8QF;_ylu=X3oDMTBrc3 VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=37mm+COW+cann on&vid=5b2caef8ee3659be2873f23ab410b5bd&l=1%3A29&turl=http%3A%2F%2Fts1.mm.bing.net%2Fth%3Fid%3DV.46 35439006549468%26pid%3D15.1&rurl=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DRz 1MSHglGP4&tit=C.O.W.+37mm+cannon+fitted+to+Blackburn+Perth+f lying+boat&c=0&sigr=11au2isnj&age=0&hsimp=yhs-01&hspart=mcafee&type=mcafee&tt=b[/video]

Notice the recoil and movement of the gun in this mount? 

A couple of MGs would do better for flak suppression.


----------



## tomo pauk (Jun 3, 2013)

A favorite plane modification of mine would be the A-36 with Vickers S cannon, the 'S' being outfitted with Littlejohn adapter. Ditch the wing MGs prior that.


----------



## merlin (Jun 3, 2013)

MacArther said:


> I like the idea, but you might need that position on a plane that big to help drop the torpedo's. Also, I don't know if structural integrity could support such a gun at the front, but more knowledgeable people would have to comment on that.



My thought there - was the bomb aimer is not necessary - the pilot can do that. In that the bomb aimer looks down to drop bombs, you don't look down when torpedo dropping, but line the plane to drop in the direction you expect the target to be. 
I had the idea that the armourers at an experimental Squadron comes across the cannon seemingly abandoned and forgotten, and try an installation on some aircraft giving some enemy ships a surprise!!


Shortround6: thanks for the info and video clip. I assumed with such a weapon - its effective range would be greater than MGs, and besides the Wellington would still have the two 0.303" in the front turret.


----------



## Shortround6 (Jun 3, 2013)

If you are torpedo bombing the nose of the plane is pointed ahead of the ship (unless it is a _really_ slow ship). torpedo is dropped on a collision course with the ship. Fixed guns don't do a lot of good for AA suppression on torpedo bombers until AFTER the torpedo is dropped at which point the pilots concentration SHOULD be on getting out of there.


----------



## MacArther (Jun 6, 2013)

Shortround6 said:


> If you are torpedo bombing the nose of the plane is pointed ahead of the ship (unless it is a _really_ slow ship). torpedo is dropped on a collision course with the ship. Fixed guns don't do a lot of good for AA suppression on torpedo bombers until AFTER the torpedo is dropped at which point the pilots concentration SHOULD be on getting out of there.


Agreed! If you are going to do a straight at pass at a ship, there are bombers better suited to skip bombing or mast-top bombing styles.


----------



## Boa (Jun 8, 2013)

I would like to modify the Yak-3, making the Klimov VK-107 more reliable, putting the exhaustvalves on the outside, making the supercharger more effective at all altitudes. A more effective wing with a more laminar flow and highspeed flaps and slats. I want 3 20mm guns, Hispano Mk. Vs. 
I think I want the Cockpitheater to give a more even heat to the pilot, at a 21* celsius. And a cooling box with icecream, vanilla... And beer... a friendly stewardess... and.. and... *

This is BOAs mom... Please, please dont let him make wishes on aircrafts, his brain just cant cope with it. 
Now he is here on the floor, drooling.
Thanks a lot..
//
BOAs mom


----------



## Civettone (Jun 9, 2013)

I would modify the Ambrosini SAI.403. It was an Italian wooden fighter. Taken into production but probably none served before the Armistice. It had a 770 hp air cooled engine, which gave it an amazing maximum speed of 640 kmh. It lacked a bit in climb rate and also its engine was single stage, plus a light armament and armour made it unsuited for high-altitude bomber interceptions. It could however be turned into an excellent dogfighter. A major problem was its light armament: it carried two Breda-SAFAT HMGs and two Mauser cannons. The SAFATs weighed 27 kgs and the MG 151s 42 kgs. These could have been replaced by 4 MG 131s, each weighing 17 kgs, giving it a similar armament as the P-51B/C. Hereby saving 70 kgs of weight.
Also possible would be to use the Hispano-Suiza 12Y engine. This produced around 950 hp and weight (dry) only 50 kgs more. CoG would be okay because the Hispano Suiza was much shorter than the Italian engine. Plus, it could get a cannon firing through the propellor hub. With the 20% added engine power, its maximum speed would be around 660-670 kmh? And also climb rate would be improved.

So you would have a wooden fighter, with a speed of at least 660 kmh, 1 MK and 2-4 HMGs ... sounds like an Italian Yak-3 to me 

In fact, Ambrosini was working on the SAI.503, which would have received the air-cooled IF Zeta engine or maybe the DB 605.
Kris


----------



## Dogwalker (Jun 9, 2013)

Really the 403 was equipped with an Isotta Fraschini Delta IV RC.17/50 (the same was used in one the SAI 207 pre production aircrafts, the MM8433), the same used in the Caproni Ca.331b _Raffica_. It was the last developement of the _Delta_, with a two speed supercharger, 870ps at takeoff, and 850ps at 5000m.
The prestations indicated for the 403 were those projected, however, we know that the SAI.207 obtained 580 km/h at 4500m with the Delta III RC.40, 750ps at 4000m, so, the 403 could reach, at best, 604km/h for the adjunctive power alone, plus something for the higher critical alitude, plus (likely) something for the different airfoil, less something for the larger wing surface.
A shame the Zeta was never fully operational, as a Zeta engined 207/403 would reach about 680 km/h (without taking into account the larger frontal surface of the Zeta, and the higer critical altitude of the Zeta RC.27/60)


----------



## Civettone (Jun 9, 2013)

DW, is 604 kmh a typo? Did you mean 640 ?

The SAI.403 had other aerodynamical refinements which added to max speed.

I think the Zeta would require a new airframe alltogether. The Zeta was essentially a double Delta, thus quite heavy!
If the Italians had managed to make it reliable and deliver 1,500 hp, it would have been their perfect engine, suited for all their fighters and bombers.

Kris


----------



## Dogwalker (Jun 9, 2013)

No, I mean 604 km/h _for the adjunctive power alone_, to which we have to add something for the higher critical altitude (850ps at *5000m*, vs 750ps at *4000m*), something (likely) for the more refined airfoil, but something less for the larger wing surface. To me, a realistic maximum speed for the 403 is from 615 to 620 km/h at about 5500m. The SAI 207 and 403 were aerodinamically very similar, it is unlikely that ing. Ambrosini has been able to do miracles from one to the other. And we can already say that Ambrosini and Stefanutti have really made miracles. Those performances are however comparable to those of a "5 series" fighter, with 500ps less.
The Zeta was not a double Delta, but a double Gamma (smaller and lighter than the Delta: 19.2l, 420kg, and the duplication of the cylinders obviously didn't duplicate the weight, since the crankcase was the same). The double Delta was the projected 1600hp _Sigma_. Don't know the actual weight of the Zeta, but Zeta engined Breda 201 was projected to weight 100kg more than the DB601 engined one. An higher weight adequate with the higher power and critical altitude.
The Zeta already would be a great engine. It's true that its power was less than that of a DB605A/RA.1050, but there wasn't the additional drag of the radiator.


----------



## Civettone (Jun 9, 2013)

I don't know if these drawing are accurate but they indicate that the design was much altered. The SAI.207 had more of a triangular cross section and the .403 a rounded one. Also the tail wheel was retractable. Is the 640 kmh figure not an official number? The aircraft was built and tested by both Italians and Germans. No data known?
I also wonder if the critical altitude shift from 4,000 to 5,000 m was not more decisive? I am not an aeronautical engineer but I do know that two-speed superchargers add a lot of maximum speed higher up.











Good call on the double Gamma, I was never sure which version was true. The Zeta delivered 1,250 hp but this seems to have been below what was expected. The Zeta was expected to get up to 1,500 hp. That made me believe it must have been a double Zeta. A 1,250 hp engine is of course not going to do be worth much, compared to the existing DB 601 aka RA.1000. 

I remember seeing the Re.2001 with the Delta engine and it had a large air intake, I assume the Zeta would require one even bigger to cool it properly. 
Kris


----------



## Dogwalker (Jun 9, 2013)

Those drawings are artistic impressions (as it's easy to say confronting the two cockpits. Or that of the 403 is too large, or that of the 207 is too small). Little differencies in the shape of the fuselage of the two aircrafts exist, but the SAI 207/403 was really hidden behind its engine (so the triangular cross-section) and a pair of MGs' barrel over it. Having the Delta III and IV the same shape and dimensions, the 403 could have a different cross section only increasing the frontal surface. As you can see in those pictures, there are little differencies in the cross ection of the aft part of the fuselage (apart from the obvious differences in control surfaces), but these can lead only to marginal differences in performance. The aerodinamic of the SAI 207 was already extremely efficient, and it is very difficult to improve much something already extreme.
The 640 km/h is official, in the sense that was estimated by the manufacturer. Unfortunately the test data did not survive to the war. 
The effects of the different critical altitude (1000m) can be estimated from 10 to 20km/h (Gianni Cattaneo, while being very critical of the project in general, estimate it in 20 km/h), but do not forget the larger wings and two cannons.









The Ra.1000 gave 1050ps at 4100m. The Zeta Rc25/60 had the critical altitude at 6000m. At that height was more powerful than a DB601E, and a little less powerful than a DB605A, but without the drag of the radiator. In fact, the Caproni Vizzola F6Z was faster than the DB605 engined F6M.

Here you can see the air intake of the Zeta (below is the oil radiator), at the time of it's homologation.













On the F6Z, with Alfa Romeo propellers.


----------



## Civettone (Jun 9, 2013)

Very interesting stuff! 

You mentioned the DB 601E. I assume that was again not a typo. Have you ever read anything about Alfa Romeo or any other company trying to upgrade their DB 601Aa to the DB 601E? It also remarkable that the DB 605 was licence produced not to AR, but to Fiat. I assume Fiat had to learn from scratch how to build these engines while AR could have switched production. Of course, AR engine works would have to be enlarged or been given control over other factories. 
Also, I have read that the DB 603 was going to be licence produced. Then again, I read a lot of rumours. I have read the Ca.313, CA.331, SAI.403 and AR.135 engine being ordered by the Germans, Kurt Tank examining the Fiat G.55 for production, etc. All seems to come from Italian publications without any evidence in non-Italian sources. Drives me crazy :/

Kris


----------



## wuzak (Jun 9, 2013)

What was the bore stroke of the IF Zeta?


----------



## altsym (Jun 10, 2013)

According to an article by David Shepherd, 160mm stroke, 132mm bore.


----------



## wuzak (Jun 10, 2013)

So the Zeta produced roughly 1/2 horspower per cubic inch.

With 132mm bore and 160mm stroke the capacity is 52.55l or 2545 cubic inches.


----------



## Dogwalker (Jun 10, 2013)

Civettone said:


> Have you ever read anything about Alfa Romeo or any other company trying to upgrade their DB 601Aa to the DB 601E?


Anything. After the DB601, the goal was to produce the DB605.



Civettone said:


> It also remarkable that the DB 605 was licence produced not to AR, but to Fiat. I assume Fiat had to learn from scratch how to build these engines while AR could have switched production.


The engine was called FIAT RA.1050, but has to be produced by Fiat (5000 ordered), Alfa Romeo (750 ordered) Isotta Fraschini (3000 ordered) and OMIR (1000 ordered). Isotta Fraschini and OMIR had not the time to set the production, and Alfa Romeo, still in 1943, had problems in building enough engines to replace the existings Ra.1000 (whose expected life was of about 60 hours of flight only. See, for example, the difficulties for IMAM to have a pair of engines for the RO.58 prototype), so the engine, in the end, was produced only by Fiat.


----------



## vinnye (Jun 10, 2013)

I would think it was a bad idea, slower rate of fire, less ammo carried, weight penalty - structural reinforcement etc.


----------



## wuzak (Jun 10, 2013)

vinnye said:


> I would think it was a bad idea, slower rate of fire, less ammo carried, weight penalty - structural reinforcement etc.



Posted in the wrong thread?


----------



## Civettone (Jun 10, 2013)

Must be ... 


Kris


----------



## Dogwalker (Jun 10, 2013)

132X160 was the Delta, and so the projected _Sigma_. The Gamma, and so the Zeta, was 125 bore, 130 stroke.


----------



## wuzak (Jun 10, 2013)

So, 38.29l/2336.5ci capacity.

Still lowish power for its capacity. 

The Rolls-Royce Exe managed 2/3 more power per litre.

I miscalculated earlier - 24 cylinders @ 132mm x 160mm = 3206ci/52.55l.


----------



## Civettone (Jun 10, 2013)

Wuzak, does the fact that it is an air cooled engine make a difference in your appreciation?

What was the rpm for these engines?

Kris


----------



## Shortround6 (Jun 10, 2013)

While the RR Exe was air cooled it ran at 4200rpm and weighed 1530lbs dry. 

The Sleeve valves may have been a problem, While both Bristol and Napier could produce prototypes that ran well ( or small scale production), mass production gave both companies quite a bit of trouble, at least to start. . Perhaps RR would be different, perhaps not.


----------



## Dogwalker (Jun 10, 2013)

wuzak said:


> The Rolls-Royce Exe managed 2/3 more power per litre.


With which gasoline?


----------



## wuzak (Jun 11, 2013)

Dogwalker said:


> With which gasoline?



Not sure. It was either 87 or 100, but probably the former because it ran pre-war.

Edit: Lumsden says it was 100 octane fuel.


----------



## wuzak (Jun 11, 2013)

Civettone said:


> Wuzak, does the fact that it is an air cooled engine make a difference in your appreciation?



I was comparing to another air cooled engine.


----------



## wuzak (Jun 11, 2013)

Also, in the scheme of things, it doesn't much matter what the specific power (power to capacity) is, but rather more what the weight of the engine is compared to teh power and the specific fuel consumption.

As Shortround says, the Exe was 1150hp but weighed 1500lbs+, with a maximum projected performance (not tested) of around 1500hp.

The de Havilland Gipsy Twelve (King I) made less than 500hp but weighed over 1000lb.


----------



## Dogwalker (Jun 11, 2013)

Civettone said:


> I have read the Ca.313, CA.331...


The Ca.331 was another aircraft worth modifiyng. With a 1000kg bomb bay, 12.7mm dorsal and ventral turrets, 2 external hardpoints, and six forward firing 12.7mm MGs (or 4 20mm cannons) it reached 505 km/h at 5300m with two Isotta Fraschini Delta IV, 850hp at 5000m.
Those prestatios and armament already compares very well with those of a Ju88 C-6 heavy fighter/nighfighter, having about 40% less power.
It would be interesting to see what could do a two seat version, without defensive turrets, and with more powerful engines.


----------



## Dogwalker (Jun 11, 2013)

wuzak said:


> Not sure. It was either 87 or 100, but probably the former because it ran pre-war.
> 
> Edit: Lumsden says it was 100 octane fuel.


Otherwise, it would have been more powerful than a 87 octane gasoline fuelled Merlin, with a lower displacement. Quite an achievement.




wuzak said:


> but rather more what the weight of the engine is compared to teh power and the specific fuel consumption


True. In this regard, it's interesting to note, for example, that a SAI.207, with 210kg of gasoline, had more range than a C.202 with 250kg (1000km vs. 765), and even the F6Z had more range of the F6M with the same amount of fuel (400kg). Other than the specific fuel consumption, we have to see the effect on consumption of the lack of radiator (less hp, and so less consumption to, achieve the same speed).


----------



## MacArther (Jun 17, 2013)

A little off topic, but can anyone tell me why two .303 machine guns were used as "aiming" devices/strafing weapons on the Hurricane Mk. IID and the Mk. IV's universal wing? I can understand the argument that Britain had an excess of .303 machine guns for craft, but wouldn't a larger round be more conducive to helping the aim of rockets, bombs, and 40mm guns? To me at least, it would seem like the lighter .303 round might not be very predictive of the path of the heavier weapons. I understand that there were sights and markings on the Hurricane's to help with aiming, but I know I've read about pilots somehow (can't remember the exact method) using the 2 machine guns to line up their target before firing the heavy weaponry.

Note: If I sound redundant in any of my questions, its because its a test day and I'm working on exactly 0 hours of sleep (mind was too active the night before with math equations).


----------



## Shortround6 (Jun 17, 2013)

A. they had them, unlike .50 cal guns.
B. the 40mm wasn't that high a velocity round.
C. the range was relatively short. Much further under 1000 yds than over 1000yds. 

MGs don't do much at all for aiming bombs and not much more for rockets.


----------



## MacArther (Jun 17, 2013)

Shortround6 said:


> A. they had them, unlike .50 cal guns.
> B. the 40mm wasn't that high a velocity round.
> C. the range was relatively short. Much further under 1000 yds than over 1000yds.
> 
> MGs don't do much at all for aiming bombs and not much more for rockets.



But would the MGs at least be loaded with Incendiary-tracer rounds so that they could track the fall of the shot better?


----------

