XP-40Q fuselage (1 Viewer)

[Piper106]

Does anyone have information on the changes made to the fuselage of the XP-40Q prototypes compared to standard P-40s.

As you know the XP-40Qs were powered with two stage (F27 and F-28) Allison engines which are both longer and heavier than a single stage V-1710 used in the P-40D / E/ K / M / N.

If the engine block for a two stage Allison was the same distance in front of the XP-40Q wing as a standard P-40, where did they find the room for the auxiliary stage supercharger? in the "Q" ??

If the XP-40Q mounted the engine block further forward from the wing to make room for the aux supercharger than standard P-40, how was balance / center of gravity maintained?? Even without moving the engine block, there is the extra weight of the 2nd stage supercharger plus the extra weight of a four blade propeller compared to a standard Allison powered P-40. Fuselage extended (ala Fw190D vs. Fw190A)? Lead block in the tail??

 

[Supercharged]

Please have a look here:

Curtiss XP-40Q Fighter

The XP-40Q was a final attempt by Curtiss to extend the life of its P-40 fighter design. While it was a good aircraft, the XP-40Q was on par or outclassed by other fighters already in production.

oldmachinepress.com

 

[tomo pauk]

If the XP-40Q mounted the engine block further forward from the wing to make room for the aux supercharger than standard P-40, how was balance / center of gravity maintained?? Even without moving the engine block, there is the extra weight of the 2nd stage supercharger plus the extra weight of a four blade propeller compared to a standard Allison powered P-40.

FWIW, the 'Prestone' radiators were reloacetd in the wing from the frontal undrnose position; on the early XP-40Qs, these were relocated under the fuselage in an ungainly 'box'. The whole liquid cooling system was about 300 lbs in a P-40, obvioulsy tnat includes the liquid iteslf and the tank, plus any pumps that are not attached to the engine. Cooling system on the 2-stage V-1710s should weight a bit more - the rather colosely-coupled system on the P-63 was at ~350 lbs.

Similar 'trick' was used on the Bf 109s when the switch from Jumo to the DB happened, as well as when the Italians were trying with DBs in the nose of their fighters.

 

[Piper106]

I had looked at te XP-40Q a number of times, but it never registered that the coolant radiators had been moved to the wings. I guess I saw that big scoop under the nose on the second and third XP-40Qs and 'assumed' the coolant radiators were still under the nose, just like a standard P-40.

As stated in the file provided by 'Supercharged', Curtiss lengthened the nose on the XP-40Qs. That takes care on the room needed for the Allison second stage supercharger. Moving the coolant radiators from the nose back to the wing near the CG, must have taken care of the balance / CG issues with the lengthened nose and heavier engine.