# Which US piston-fighter prototype do you like best?



## Oreo (Aug 3, 2008)

I may not post all the available possibilities here, but the basic idea is to see which of these prototypes intrigues you the most or makes you wish it could have made it into combat to prove itself. If you're not familiar with these types, I suggest you look up images of them. Google images will do if you can't find them elsewhere.

Don't squawk to me about jets. If you want one about jets, make your own poll!


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## FLYBOYJ (Aug 3, 2008)

XP-55!!!!


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## Oreo (Aug 3, 2008)

I chose the Boeing XF8B. A big heavy single-engine, single-seat fighter designed for carrier use, with 28-cylinder 4-row "corn-cob" engine, internal bomb bay for 3,200 lbs. of bombs, up to 6x20mm cannon, 2,800 miles range, a max speed of 432 mph, and a tail like a B-17. Could have done a lot of ground-pounding in Korea. . . . or invasion of Japan!


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## kool kitty89 (Aug 3, 2008)

In looks the XP-55 was pretty cool.


I like the XP-47J the best, more practical in terms of proven design and available timeline than the XP-72 (in terms of engine availability mostly, but also in cost and complexity -the huge torque of the R-4360 necessitated the use of contrarotating props to be managible). Recorded performance also seems to be better on the XP-47J, except climb.
But I guess that wouldn't count as it's just a variant of the P-47 (though in many ways so was the XP-72).

Of that list I'm not really sure what to choose yet though.

The XF5U was interesting and seemed promising, too bad the USN didn't allow Vought to even test the completed prototypes... (even while being eclipsed by jets it was interesting in the STOL/near VTOL concept, and possibly still useful, particularly considdering -with hindsight- the failure of Vought's later XF6U)


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## Gnomey (Aug 3, 2008)

Got to love the XF5U but for me it is the XP-55.


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## otftch (Aug 3, 2008)

McDonnel XP-67. Wow !
Ed


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## B-17engineer (Aug 3, 2008)

xP-55....lol


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## kool kitty89 (Aug 3, 2008)

Just curious, what are the reasons for choosing the XP-55? (Just looks?)


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## FLYBOYJ (Aug 3, 2008)

It's looks and advanced design - I think it probably could of worked out had more time and the right engineering staff worked on it.


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## kool kitty89 (Aug 3, 2008)

I think the Bell XP-59 (piston engined twin boom pusher, not jet) had some promise too.


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## johnbr (Aug 4, 2008)

What the xp55 need was a jet engine.The xp 67 it need RR Crecy with 2 stage.


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## SoD Stitch (Aug 4, 2008)

XP-58 "Chain Lightning", mostly because I really like the P-38.


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## kool kitty89 (Aug 4, 2008)

I'm not sure how the XP-55 would have done with a jet engine, possible but maybe not practical. The J31 would leave it underpowered, and the J33 would be too large, maybe the lisence-built Goblin -J36- would work. Maybe a pair of J30's would work, or a J34, but those weren't ready until the end of the war. (in the case of the J34, after) And either way the range would be shortened considerable over the piston engined version. 

It could have used a more powerful engine, probably the Merlin. (maybe one of the later Allisons, like the P-63 had)

I don't think the swept wing was used for mach limit/transsonic drag reasons though. (I think it was for stability reasons and proper positioning of the rudders) They would have an effect on the mach behavior, but like the Me 262, Me 163, and others it was a coincedental feature. The canard layout should also allow better control in the trans-sonic region. But the sewpt wing also resulted in the long take-off run, and dangerous tip stalling and spin behavior. 
This problem should have been fairly easily solved with leading edge wing slats though.


I hadn't realized there was a surviving example: Curtiss XP-55 Ascender: Murdoc Online
On of the few prototypes on this list that did.


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## ONE_HELLCAT (Aug 12, 2008)

I wish I could pick three. For looks and hopeful performance I would've gone with the XP-55,56, and XF5U. I chose the XP-56 overall for looks and because I forgot the Flying Pancake was on the list.

Also, anyone know where I can find more of this? Looks kinda interesting.


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## Screaming Eagle (Aug 12, 2008)

just type XF5U into google images. I did, and found a whole heap of interesting pics.


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## eddie_brunette (Aug 12, 2008)

Moonbat for me:

Specifications (XP-67)

General characteristics
Crew: one, pilot
Length: 44 ft 9 in (13.64 m)
Wingspan: 55 ft (16.76 m)
Height: 15 ft 9 in (4.80 m)
Wing area: 414 ft² (38.50 m²)
Empty weight: 17,745 lb (8,050 kg)
Loaded weight: 22,114 lb (10,030 kg)
Max takeoff weight: 25,400 lb (11,520 kg)
Powerplant: 2× Continental XI-1430-17/19 twelve cylinder inverted vee liquid-cooled engine, 1,350 hp (1,000 kW) each

Performance
Maximum speed: 405 mph at 25,000 ft (650 km/h)
Range: 2,385 statute miles (3,840 km)
Service ceiling 37,400 ft (11,400 m)
Rate of climb: 2,600 ft/min (13 m/s)
Wing loading: 53.4 lb/ft² (260 kg/m²)
Power/mass: 0.06 hp/lb (0.09 kW/kg)

Armament
Six 37 mm M-4 cannon










edd


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## drgondog (Aug 12, 2008)

eddie_brunette said:


> Moonbat for me:
> 
> Specifications (XP-67)
> 
> ...



With the Merlin 1650-9 it might have had spectacular performance at 25,000 feet, similar to Do 335, with approximately 900 more Hp in each engine at 90" boost


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## kool kitty89 (Aug 14, 2008)

Probably would have done well with turbocharged Allisons as well. (particularly as it had already been designed to encorporate turbocharged engines)


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## Trilisser (Jul 13, 2012)

The XF8B: good performance, excellent and easy handling (the pilot manual allows even snap rolls without external stores) coupled with excellent load carrying capability with highest VNE for a piston aircraft I know of (625 mph IAS according to the pilot manual reproduced in Jared Zichek's superb XF8B monograph).


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## oldcrowcv63 (Jul 14, 2012)

Northrup XP-56... 

General characteristics

Crew: one, pilot
Length: 27 ft 6 in (8.38 m)
Wingspan: 42 ft 6 in (12.96 m)
Height: 11 ft 0 in (3.35 m)
Wing area: 306 ft² (28.44 m²)
Empty weight: 8,700 lb (3,955 kg)
Loaded weight: 11,350 lb (5,159 kg)
Max. takeoff weight: 12,145 lb (5,520 kg)
Powerplant: 1 × Pratt Whitney R-2800-29 radial, 2,000 hp (1,492 kW)
Performance

Maximum speed: _*465 mph at 25,000 ft*_ (749 km/h)
Range: 660 miles (1,063 km)
Service ceiling: 33,000 ft (10,061 m)
Rate of climb: 3,125 ft/min at 15,000 ft (953 m/min)
Wing loading: 37 lb/ft² (181 kg/m²)
Power/mass: 0.18 hp/lb (0.96 kW/kg)
Armament

2 × 20 mm (.79 in) cannons
4 × .50 in (12.7 mm) machine guns

Unfortunately, like my other favorite, The XP-67 Moonbat, it never fullfilled its promise,


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## wuzak (Jul 15, 2012)

oldcrowcv63 said:


> Northrup XP-56...
> 
> General characteristics
> 
> ...



The performance shown in that chart would only have been Northrop's predicted performance. Its actual performance was around 100mph less. I believe it was also very unstable. I have a book around here on the XP-54, XP-55 and XP-56 - but I can't find it at the moment.

Talking of unstable - two of the XP-55s crashed. The first stalled and flipped on its back during stalling tests. The engine cut out and with no forward momentum no recovery could be attempted. It fell several thousand feet vertically and landed on its back. The test pilot managed to escape - though it took him some time to get out. The other one to crash did so at an air show demonstration, hitting a car on a highway and killing (IIRC) its occupants - this is post war.

The XP-67 showed similar performance to the XP-49 - a cleaned up P-38 fitted with turbocharged Continental IV-1430s.

Specifications (XP-49)

General characteristics
Crew: One
Length: 40 ft 1 in (12.2 m)
Wingspan: 52 ft (15.8 m)
Height: 9 ft 10 in (3.0 m)
Wing area: 327.5 ft² (30 m²)
Empty weight: 15,410 lb (6990 kg)
Loaded weight: 18,750 lb (8505 kg)
Powerplant: 2 × Continental XI-1430-1 inverted V-12s, 1,600 hp (1,193 kW) each

Performance
Maximum speed: 406 mph (653 km/h) 15,000 ft (4,570 m)
Range: 679 mi (1,093 km)
Rate of climb: 3,300 ft/min (16.8 m/s)

Armament

2 × 20 mm (.79 in) cannons
4 × 0.5 in (12.7 mm) machine guns

It is unlikely that the IV-1430s ever reached their rated power in flight, and probably barely made over 1000hp.

Merlins or Allisons of 1600+hp would have been great in the XP-67. Drop the 6 x 37mm for 4 x 20mm, put in 2 stage Merlins or Allisons - or, more radically, try out some Sabres hooked up to C-series turbos (from scale drawings it looks as though those nacelles are large enough to house a Vulture (which was discontinued before the XP-67 was started, of course) or a Sabre. Imagine 4800hp in that baby instead of the 2000hp or so that they had! And with the turbo this power could be maintained to 30,000ft.

Yes, the XP-67 is it for me. 

btw, the book I mentioned before

Amazon.com: American Secret Pusher Fighters of WWII: XP-54, XP-55, and XP-56 (9781580071253): Gerald H. Balzer: Books


shows a drawing of the predecessor of the XP-67 - the McDonnell Type/Model 1, with fuselage maounted single engine (V-3420, H-2600 among the options) driving a pair of wing mounted pusher props via gearboxes, right angle drives and extension shafts.


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## R Pope (Jul 18, 2012)

I figure the Blackhawks knew best! They flew F5F's! Hawkaaaaaaaaa!


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## grampi (Jun 14, 2017)

I'd pick one that wasn't on the list...don't know if it qualifies as a prototype, because it was a variant of a plane that was produced, but it was the P-51G...it was said to have a top speed of 500 MPH, and a climb rate of 5000+ fpm...in fact, I'm not quite sure why the P-51H was chosen over the G model as it sounds like the G was a better performer...


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## tomo pauk (Jun 15, 2017)

grampi said:


> I'd pick one that wasn't on the list...don't know if it qualifies as a prototype, because it was a variant of a plane that was produced, but it was the P-51G...it was said to have a top speed of 500 MPH, and a climb rate of 5000+ fpm...in fact, I'm not quite sure why the P-51H was chosen over the G model as it sounds like the G was a better performer...



The P-51H was the 'useful P-51G' - 150% more fuel + drop tank facility, and 50% more .50s. The speed was in the ballpark - 470+ mph for both.
link


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## davparlr (Jun 20, 2017)

Old thread but I have to comment. In my opinion, one of the most impressive XP plane was the XP-72 which first flew in February, 1944. With its supercharged 3500 hp, with a future possibility of 4000 hp, it seems by all accounts, to have "displayed exceptional performance" per wikipedia and others, so much so the Air Force ordered production of 100. If aggressively pursued, it could have reasonably been a 500 mph fighter in the summer and surely fall of 1944. Changing war situation emphasized long range escort over high speed interceptors and the order was cancelled.


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## wuzak (Jun 22, 2017)

davparlr said:


> Old thread but I have to comment. In my opinion, one of the most impressive XP plane was the XP-72 which first flew in February, 1944. With its supercharged 3500 hp, with a future possibility of 4000 hp, it seems by all accounts, to have "displayed exceptional performance" per wikipedia and others, so much so the Air Force ordered production of 100. If aggressively pursued, it could have reasonably been a 500 mph fighter in the summer and surely fall of 1944. Changing war situation emphasized long range escort over high speed interceptors and the order was cancelled.



Doubtful that more than a handful P-72s could be built before the end of 1944. 

Also, at that stage the R-4360 was "only" producing 3,000hp. 3,500hp was a couple of years into the future and 4,000hp was some way off.

And I dare say that the advent of jets would have cut the P-72's career very short.


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## swampyankee (Jul 4, 2017)

X5U was probably the most innovative piston-engined aircraft prototype of its era. That's why it got my vote.


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