Northrop XP-56J

[steelpillow]

Some of you will be familiar with the Northrop XP-56 "Black Bullet" project during WWII. It was a tailless fighter of all-magnesium construction, with pusher propeller and curious turned-down wingtips. Two examples were built. The first flew just long enough to establish that it was barely controllable, before it was destroyed when its nosewheel collapsed during high-speed taxiing trials. The second was heavily modified. It suffered nose-heaviness when the gear was down, while engine cooling was insufficient to attain high-speed flight. Today the machine is a museum piece. So much is well known. But fewer people know that there was a third follow-up machine a couple of years later. This abandoned the troublesome rear piston engine installation for a de Havilland Goblin. Although the de Havilland vampire, first UK fruits of the Goblin, was a lighter craft than the XP-56 and with a smaller span, fuselage lengths are almost identical. The Goblin fitted the XP-56 comfortably, using the same root-mounted air intakes as the piston engine's radiators. The plan was to fit the more powerful Ghost engine when it became available (Which in the Vampire turned it into the Venom).

Related modifications included a revised nose undercarriage, cut-down canopy rear frame and the upper fuselage behind, reduced area of the lower fin and equivalent increase in the upper fin, and two stubby extensions to the wingtips. These were rigged with a negative incidence to produce a downforce in level flight. Perhaps paradoxically to the uninitiated, this cured the stability issues. The basic theory was worked out by J W Dunne between about 1904 and 1909. It was in fact Northrop trying to cut corners with Dunne's theory that caused the aerodynamic problems in the first place.

The prototype jet was naturally enough dubbed the XP-56J and flew in 1946. It was fast, manoeuvrable and - you can guess - politically the wrong machine at the wrong time and in the wrong place. It got tarred with the XP-79 flying wing brush and cancelled with the same red pen. Anyway, here it is:

[kitbasher]

Very similar to de Havilland's Viper (http://www.arcair.com/Gal-Archives/jet/Viper/01.shtm).

[Jesse220]

Not bad  

[PR19_Kit]

Logical and looks great, what's not to like? 

[NARSES2]

As kit says it's logical and looks good 

You mention Titanium being used in the build of the XP-56 ? I thought it was Magnesium alloys which is why it was such a fire hazard and they had a heck of a job welding the thing ? I think they had to weld it in a sand pit so they could keep putting the fires out. Or am I thinking of another aircraft entirely ?

[Tophe]

Lovely! I imagine a twin-pod zwilling version, but the twin-boom version that I dream of would be quite different, less pure.

[Tophe]

Lovely! I imagine a twin-pod zwilling version, but the twin-boom version that I dream of would be quite different, less pure.

Here is my dream, thanks!

[PR19_Kit]

That'll be the XP-112 then........... 

[Tophe]

And the XP-56 reached 465 mph, the XP-56J reached 600mph (steelpillow will confirm), so the XP-56ZJ reached 1,200mph, this is mathematics, no?

[steelpillow]

Lovely! I imagine a twin-pod zwilling version, but the twin-boom version that I dream of would be quite different, less pure.

Here is my dream, thanks!

That looks eerily close to the XP-79B https://commons.wikimedia.org/wiki/File:Northrop_XP-79.jpg

[steelpillow]

 

And the XP-56 reached 465 mph, the XP-56J reached 600mph (steelpillow will confirm), so the XP-56ZJ reached 1,200mph, this is mathematics, no?

Ah, but it reached it in the Z direction, which as we all know is straight down...

Actually the XP-56J may have been fast by the standards of the day but it wasn't that fast compared to say the near-contemporary and similarly engined tailless swept de Havilland DH.108 Swallow. Being bigger it was really waiting for the more powerful engine, and while the tip extensions cured the instability they added drag. Max speed was 612 mph, comfortably faster than say the 580 mph of the Lockheed F-80 but less than the Swallow's 677 mph. With the planned engine and redesigned wingtips, max speed of the production version was estimated at 635 mph. It would have been limited by the critical Mach number of the gently-swept wing rather than anything else.

[Captain Canada]

Very cool. Those things look so big and heavy tho....still be a cool build !

[steelpillow]

ou mention Titanium being used in the build of the XP-56 ? I thought it was Magnesium alloys which is why it was such a fire hazard and they had a heck of a job welding the thing ? I think they had to weld it in a sand pit so they could keep putting the fires out. Or am I thinking of another aircraft entirely ?

That's funny, I always thought Magnesium was spelled with a "T". Thanks for the tipoff. I have now corrected my spelling, ahem. 

[Jesse220]

Good, but even if they made a jet variant of that plane, it would also be to difficult to fly.

[Tophe]

And the XP-56 reached 465 mph, the XP-56J reached 600mph (steelpillow will confirm), so the XP-56ZJ reached 1,200mph, this is mathematics, no?

Actually the XP-56J may have been fast by the standards of the day but it wasn't that fast compared to say the near-contemporary and similarly engined tailless swept de Havilland DH.108 Swallow. Being bigger it was really waiting for the more powerful engine, and while the tip extensions cured the instability they added drag. Max speed was 612 mph, comfortably faster than say the 580 mph of the Lockheed F-80 but less than the Swallow's 677 mph. With the planned engine and redesigned wingtips, max speed of the production version was estimated at 635 mph. It would have been limited by the critical Mach number of the gently-swept wing rather than anything else.

Thanks for this top-secret part of History