XP-46

Some additional info -Post-1
 

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Wonderful! You have put a smile on this big Curtiss fan's face!
 
Hi guys! Does it exist a kit (1/72) of this aircraft? (plastic or resin, it doesn't matter)
 
Hi Redstar72, thank kou for the link, but the XP-46 is unfortunately sold out...
 
A drawing by Jan Kadlec from Czech L+K magazine, 9/1969:
 

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Here's a shot I haven't seen before of the unarmed XP-46A (40-3054) doing what looks like a high-speed taxi test. -SP
 

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I found these XP-46 era Curtiss test pilots but I do not which one was the pilot:
Henry Lloyd Child
Barton Travers "Red" Hulse
Everett Edward "Ed" Elliot
Herbert O. Fisher
William O. "Bill" Webster
Robert W. "Bob" Fausel
 
Has anyone read of an explanation for why some of the pictures show the inboard landing gear doors open when they should be closed?
 
Apparently USAAF took delivery of the two prototypes 40-3053 and 40-3054 and used them? Anybody who has information of their use?
 
Looks a sweet bird: What did designer get so wrong ? Wing-span short ? Was it just the weighty accumulation of real-neat features ??

{ Apologies for terseness, duty-cat has woken and resumed her enthusiastic sub-editing... }
 
Looks a sweet bird: What did designer get so wrong ? Wing-span short ? Was it just the weighty accumulation of real-neat features ??

{ Apologies for terseness, duty-cat has woken and resumed her enthusiastic sub-editing... }

I think the balance of tail beam,it need to be longer and smooth.
 
Looks a sweet bird: What did designer get so wrong ? Wing-span short ? Was it just the weighty accumulation of real-neat features ??

{ Apologies for terseness, duty-cat has woken and resumed her enthusiastic sub-editing... }

Curtiss reputation and efficiency was going down the drain at the speed of sound or even faster.
 
Looks a sweet bird: What did designer get so wrong ? Wing-span short ? Was it just the weighty accumulation of real-neat features ??

{ Apologies for terseness, duty-cat has woken and resumed her enthusiastic sub-editing... }
The design was already largely obsolete. The Allison engine was insufficiently powerful and not yet fully reliable. . The early reduction gear was a problem. Worse, it lacked adequate altitude performance. The single-stage supercharger was too small and too inefficient, having been designed for use as a second stage following a first-stage turbocharger . Fitting a turbocharger into something the size of the P-46 would have been pretty much impossible (look at the bulk of the installations in P-38s and P-47s). Without a better engine, the P-46 did not offer enough improvement over the P-40 to warrant production.
 
The P-40F with the Packard Merlin did not very much either, was it just a 'draggy' airframe or overweight?
 
The P-40F with the Packard Merlin did not very much either, was it just a 'draggy' airframe or overweight?
Looks a sweet bird: What did designer get so wrong ? Wing-span short ? Was it just the weighty accumulation of real-neat features ??

{ Apologies for terseness, duty-cat has woken and resumed her enthusiastic sub-editing... }
The design was already largely obsolete. The Allison engine was insufficiently powerful and not yet fully reliable. . The early reduction gear was a problem. Worse, it lacked adequate altitude performance. The single-stage supercharger was too small and too inefficient, having been designed for use as a second stage following a first-stage turbocharger . Fitting a turbocharger into something the size of the P-46 would have been pretty much impossible (look at the bulk of the installations in P-38s and P-47s). Without a better engine, the P-46 did not offer enough improvement over the P-40 to warrant production.
The 'standard' for comparison was the X73 prototype which flew some 4 months earlier than the XP-46. Same engine V-1710-39, same fuel capacity (156gal)

The X73 was basically 10% larger in length, wing span and wing area, 265 pounds lighter with full fuel of 156gal, full load of ammo, armor plate, self sealing tanks (X73 7400 to XP-46 7665).

The X73 flew 20mph faster with full load of fuel/noguns (375 to 355) and farther (900 to 755). The improved cooling system of the NA-73 production Mustang flew 30mph faster and also 300 mi farther - only two months after the first prototype XP-46 and before XP-46 #2.

The shorter wing span of the XP-46 should have been a slight advantage but it used the NACA 23015 airfoil section compared to the high speed/low drag wing NAA/NACA 45-100 of the Mustang.

The fuselage of the Mustang is a 2nd degree conical sections with gradually increasing velocity gradiant all the way to the intake scoop under the cockpit and behind the lifting line. The XP-46 has an immediate 'bump'/disruption with the presence of the first intake scoop, then has the non-adjustable intake scoop immersed in the wake of the boundary layer separation aft of the lifing line of the wing.

I have no idea what the surface quality of the XP-46 ws, but NAA began with high quality, even though X73 was hand made. Tight butt joints, no gaps, flush rivets, but without the now famous wing surface treatment of the production Mustang.

The production NA73/Mustang I was 30 mph faster than XP-40, despite growing 1000 pounds (8642 vs 7665), and flew 300 mi further with full combat load.

The difference wasn't just Schmued vs Berlin, as Kindelberger formed a project manager team which transformed the Preliminary design parts and asemblies to high tolerance, semi-mass production standard process plans/production assemblies to build high quality with both an eye to minimizing time on the plant floor.

If there ever was a smoking gun condemning Materiel Command's CO, Col/Gen Oliver Echols lack of judgment, the attempts to 'fix' the XP-46 while ignoring the XP-51 is very high on the list. His later attempt to bury the A-36, then the P-51A IMO showed vindictiveness toward NAA for saluting him with middle digit when rejecting his order to build the P-40 for the Anglo France Purchasing Board. When he clung to the XP-75 despite the introduction of the 85 gal fuse ank for P-51B and LE fuel tank for P-38 showed perhaps his stupidity - or perhaps planning for future career after WWII ended?
 
NA-73X was the original Mustang prototype.

NA-73: Mustang 1, XP-51
NA-83: Mustang 1a
NA-91: P-51, Mustang 1a
NA-97: A-36
NA-99: P-51A
Etc. up through NA-139 which was a canceled block of P-51H.

Note that while the NAA NA numbers have been used as model numbers, they're actually
engineering charge numbers.
 
...The shorter wing span of the XP-46 should have been a slight advantage but it used the NACA 23015 airfoil section compared to the high speed/low drag wing NAA/NACA 45-100 of the Mustang...

What was the correct airfoil for the XP-46?

Wikipedia used to say "Airfoil: root: NACA 2215; tip: NACA 2209" (supposedly taken from NASA/Langley Research Center archive documents).

Now, Wiki has "Airfoil: root: NACA 23016.5; tip: NACA 23009" based on David Lednicer's list:
-- https://m-selig.ae.illinois.edu/ads/aircraft.html
 
NA-73X was the original Mustang prototype.

NA-73: Mustang 1, XP-51
NA-83: Mustang 1a
NA-91: P-51, Mustang 1a
NA-97: A-36
NA-99: P-51A
Etc. up through NA-139 which was a canceled block of P-51H.

Note that while the NAA NA numbers have been used as model numbers, they're actually
engineering charge numbers.
You are correct. NA-73 was the charge number. All the accrued P-509, X73, XX73 (Static Test version) funding were rolled into the NA-73. X73 and X-73 is the NAA project nomenclature for the prototype.

That said, the charge number for the most part is freqently synonymous with the model diferentiation. For example the NA-102 P-51B-1-NA is clearly different from NA-104 P-51B-5, -10 and -15. The Contract AC 30479 with AAF spawned NA-99, NA-104, NA-106.

NA-103 for P-51C was under AC 33940 for C-1,-5 and first two blocks of C-10, but NA-111 picked up last block of C-10, then phased nto D-5-NT, and so on.

When NA-106 for P-51D & D-1 were cancelled in October 1943, the NA-106 funding was rolled into NA-109 and NA-104 for extension of B-10-NA's beyond 42-106540. When NA-107 was canceled, the funding was rolled into NA-103 and NA-111.

I have been down many ratholes, as I see you have.
 
Possibly be changed to XP-46 thread, But-

I have never seen the Profile General Arrangement drawing showing location of radiators for glycol cooling as well as the oil cooler.

Does anyone know where I can look?

Regards,

Bill Marshall
 

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