Italy VS USA: Different ways to improve the P-35

[Airborne2001]

One lesser known aviation story that fascinates me is how Reggiane and Seversky/Republic both evolved the P-35 into fearsome fighters through different means.

We start with the P-35:

One of the first of the new generation of modern monoplane fighters with retractable landing gear.

Then the divergence happens; Reggiane copies and improves it as the Re.2000 and Seversky tries the XP-41:

XP-41 Re.2000

Both aircraft have improved aerodynamics, and other modifications to the P-35. Both were (mostly) dropped in favor of other designs, but the Re.2000 did get some work with Italy and was exported to Hungary and Sweden.

Then differences become more apparent with the P-43 vs the Re.2001*:

P-43 Re.2001

The XP-41 was dropped in favor of the P-43 with its high altitude capabilities, and the latter was relatively fast for its first flight in 1940. The Re.2001 was more for medium/low altitudes), and the aircraft became different from Seversky/Republic in that the design now had an inline engine in place of a radial.

Finally the two developments couldn't feel more different with the P-47 and the Re.2005:

P-47 Re.2005

The P-47 emphasized high speed at high altitude in the form of a rather heavy aircraft design. The Re.2005, on the other hand, was a significantly lighter design that put an emphasis on mobility. The P-47 was a strong multi-role aircraft. The Re.2005 also could be used as a ground attack aircraft but it truly was a regular fighter at heart.

I've been interested in this for a bit, so I figured I would make this my first thread aside from my intro . This is a brief run through of how the Seversky P-35 took notably different developments through the lenses of Reggiane and Seversky/Republic. Being in the US resulted in a rugged, fast, and heavy multi-role fighter, whereas being in Italy resulted in an elegant and maneuverable fighter.

Thoughts?

(I take no credit for any pictures in this post.)

*The Re.2002 is yes integral to the Reggiane fighter development, BUT it was made as a dedicated ground attack aircraft. Therefore I left it out of the comparison.

 

[T Bolt]

Very interesting thread. Somehow, I never really made the connection that the P-47 and Re2005 descended from the same grandparent.

 

[bf109xxl]

Thoughts?

The answer from Captain Obvious: the Italians needed a maneuverable fighter and the Americans needed a heavy multi-role aircraft that could escort bombers and attack ground targets.

PS. Why only Italy and the U.S.? There was a "third way". Not exactly a direct descendant, but a very close relative.

 

[Airborne2001]

The answer from Captain Obvious: the Italians needed a maneuverable fighter and the Americans needed a heavy multi-role aircraft that could escort bombers and attack ground targets.

PS. Why only Italy and the U.S.? There was a "third way". Not exactly a direct descendant, but a very close relative.
View attachment 785460

Interesting! I can see some similarities for sure.

Though for me the PZL P-50 felt a bit more like an NA-50 to me:

(Not related but similar looks.)

Or perhaps a boomerang with the more similar wings:

 

[GrumpyOldCrewChief]

One of several of the major factors to be considered in this divergence in the paths will have to be the relative power from the available powerplants. Italy never domestically had the R-2600/R-2800/Merlin class of aero engines. The home-grown engines never rose to this level, and the license-built German ones were not what the Italian design philosophy would find a decent slot for.
My humble opinion, YMMV.

 

[tomo pauk]

One of several of the major factors to be considered in this divergence in the paths will have to be the relative power from the available powerplants. Italy never domestically had the R-2600/R-2800/Merlin class of aero engines. The home-grown engines never rose to this level,

Well put.
Engine - at least in the days of gunfighters - was a heart of a fighter aircraft.

and the license-built German ones were not what the Italian design philosophy would find a decent slot for.

Italians found very quickly the good slots for the licence-built German engines, talk a few months between the engine being made available and the flight of a prototype (several of them, actually). Problem for Italy was that the production of the said engines was meager, leaving the Italians between the rock and the hard place.
Germans shipped engines and whole aircraft in the attempt to bulk up the numbers required.

 

[GrumpyOldCrewChief]

I meant that the Italians generally hewed to roughly the same sort of fighter philosophy the Japanese did. Lighter, more maneuverable airframes were preferred over heavier, but more ultimately versatile designs. The rigidity of thought of the separation of fighter v. light attack v. heavy bomber was also clung to long after the Allies were seeing the utilities of powerful fighters being multi-role. Big, heavy engines that were needed to generate the power wanted had a difficult time being shoehorned into smaller, lighter airframes designed for lower power, lighter engines, and more emphasis on maneuverability over utility. An R-2800 could not be put in a P-35 airframe.

 

[SaparotRob]

Not with that attitude.

 

[Airborne2001]

Well put.
Engine - at least in the days of gunfighters - was a heart of a fighter aircraft.


Italians found very quickly the good slots for the licence-built German engines, talk a few months between the engine being made available and the flight of a prototype (several of them, actually). Problem for Italy was that the production of the said engines was meager, leaving the Italians between the rock and the hard place.
Germans shipped engines and whole aircraft in the attempt to bulk up the numbers required.

I meant that the Italians generally hewed to roughly the same sort of fighter philosophy the Japanese did. Lighter, more maneuverable airframes were preferred over heavier, but more ultimately versatile designs. The rigidity of thought of the separation of fighter v. light attack v. heavy bomber was also clung to long after the Allies were seeing the utilities of powerful fighters being multi-role. Big, heavy engines that were needed to generate the power wanted had a difficult time being shoehorned into smaller, lighter airframes designed for lower power, lighter engines, and more emphasis on maneuverability over utility. An R-2800 could not be put in a P-35 airframe.

Not with that attitude.

I made a post back in March talking about Reggiane's Re 1 engine series. Had they been able to produce these engines in a more industrialized Italy with better access to resources, then this series would have been their Merlin/DB 6 equivalent.

Reggiane Re 10X Engines

https://oldmachinepress.com/2015/08/31/reggiane-re-101-to-re-105-aircraft-engines/#comments http://www.reggiane.info/lang1/motori.html (Full credit to the above sources for information.) In an alternate reality where Italy had a production capacity on par with the other major powers, these...

www.secretprojects.co.uk

 

[tomo pauk]

I meant that the Italians generally hewed to roughly the same sort of fighter philosophy the Japanese did. Lighter, more maneuverable airframes were preferred over heavier, but more ultimately versatile designs. The rigidity of thought of the separation of fighter v. light attack v. heavy bomber was also clung to long after the Allies were seeing the utilities of powerful fighters being multi-role. Big, heavy engines that were needed to generate the power wanted had a difficult time being shoehorned into smaller, lighter airframes designed for lower power, lighter engines, and more emphasis on maneuverability over utility. An R-2800 could not be put in a P-35 airframe.

I'd say that Allied heavy bombers were still the very different beasts when compared with their light attack aircraft, let alone the fighters. Neither the Spitfire nor Mustang were any good when it was the time to drop 4000 lb cookies above Germany, while neither A-20, SBD nor Mosquito were any good to take off with the 12000 lb cookie, let alone to deliver it where needed. Allied powerful fighters in multi-role happened mostly after Italy signed armistice.
We can note that Italians had no problems in outfitting their light aircraft (including these with fighter A/C genes) with good-sized bombs, and even torpedoes.

Italy have had no heavy, 2000+ lb/2000 HP class engines anyway. The 1300-1500 HP engines were good for the Italian fighters, once available (1943 and on), making the up-engining a pretty easy job, while giving an useful boost in performance vs. their legacy fighters. Again, making handful of these engines in 1943-44 will not going to cut it.

Italian airframe designers were realistic - there is no point in designing a fighter for a 2000 HP engine, when the 850-1000 HP engines were all that was available from the engine companies in the late 1930s. Trying to hand-wave the big and powerful engine is all fine and dandy, but it will not make anything in reality.
The R-2800 will not fit on the P-35; installing the V-1710 on a P-36 airframe was a good job however.

 

[Shortround6]

The Unbuilt XP-44 pretty much the shows the limit of the P-35.

The P & W R-2180 engine was also sort of a 1/2 way point. 14 of the same size cylinders used on the R-2800 so the engine isn't any smaller in diameter and at 1650-1700lbs it was approaching the limits of the airframe. About 200lbs heavier than the R-1830 using in the P-43. By the time the US got the P-43 where they wanted it in regards to fuel tanks, armor and guns (four .50s) the plane was heading for 7500lbs normal gross and and overload of under 8500lbs.
Now stick in a larger, heavier engine and six .50s ??

For the Italians the problem is that none of their 18 cylinder engines paned out and the two 14 cylinder engines were not big enough or strong enough (no center bearing).

 

[marathag]

For the Italians the problem is that none of their 18 cylinder engines paned out

Look at that Piaggio beast, monster displacement

light for its displacement, but Big frontal diameter, and SLOW turning to get that 1500hp from 87 octane.
To use that in a fighter, would need cranked wings to get the ground clearance for that also big prop

With say, the development that Dodge put into fixing the Wright R-3550 to a somewhat reliable powerplant by 1945, this engine along with a decent supercharger, this engine could have done something.

The way that the Moose ran Italy, Fiat would always be favored so this was a slim chance.

Only way this could happen if Italy joined the Allies in 1940, and would get boatloads of tech advisors, machine tools and high octane gasoline

 

[Shortround6]

With say, the development that Dodge put into fixing the Wright R-3550 to a somewhat reliable powerplant by 1945, this engine along with a decent supercharger, this engine could have done something.

Only way this could happen if Italy joined the Allies in 1940, and would get boatloads of tech advisors, machine tools and high octane gasoline

Now go back to the page for the Wright R-3350 and note some of the differences. The Wright used a bigger piston and shorter stroke. But the big difference was the weight. The Italian engine was about 600lbs lighter than even the early R-3350s used in the XB-19. There were reasons, The engines used in the B-29s gained another 200-300lbs.

I will note that the Italians claim to be getting about 1 hp per 1.25lbs of engine weight. The early R-3350 got 1 hp per about 1.2lbs of engine weight. I don't know if Piaggio actually reached their goal ?

 

[marathag]

Now go back to the page for the Wright R-3350 and note some of the differences. The Wright used a bigger piston and shorter stroke. But the big difference was the weight. The Italian engine was about 600lbs lighter than even the early R-3350s used in the XB-19. There were reasons, The engines used in the B-29s gained another 200-300lbs.

I will note that the Italians claim to be getting about 1 hp per 1.25lbs of engine weight. The early R-3350 got 1 hp per about 1.2lbs of engine weight. I don't know if Piaggio actually reached their goal ?

I think the late R-3350 were around the normal maximum safe piston speed of 3000ft/m, while the Piaggio running a sedate 2425 and a bit less compression. Playing it really safe, and still had issues.

I think their poor fuel really handicapped them, along with primitive supercharger section, but still seemed to have the same fuel consumption rate per HP as the Wright, so efficiency should also be similar.

 

[Jugman]

Actually the P-44 mock-up ( a YP-43 fuselage and left wing) had one of the R-2800-A pre production example installed in it. The oil cooler installation wasn't great but otherwise it fit just fine. According to Bodie Republic records refer to this version as proposal P-44-IV or model AP-4J. Many sources list AP-4J as the model number that was ordered.

Regardless of what was to power the P-44, it's not at all impossible for an aircraft that size to handle an engine in the weight and power range of the R-2800. It is uncommon, but not impossible or necessarily difficult to modify an existing design to handle such an increase in size. The Spitfire, Bf 109, and P-36/40 are all good examples.