[WWII] Grumman XF5F Skyrocket naval fighter (USA)

[copeab]

Grumman XF5F Skyrocket
Copyright 2010 by Brandon Cope

The XF5F was a twin-engine, twin-rudder single-seat fighter built for the US Navy and first flew in 1940. The most distinctive feature of the plane was that the nose was behind the leading edge of the wing, giving the aircraft the appearance of a wing flying along that a fuselage had desperately latched on to for a ride. During testing, however, the nose was slightly extended, as well as other small changes. While the plane performed well enough in flight, it was decided that a fresh, more capable design should be undertaken (leading to the F7F Tigercat, which arrived too late for the war). The XF5F had double the climb rate of the F4F Wildcat and was better than the later F6F Hellcat and F4U Corsair. Unfortunately, the Navy wasn't yet ready for a twin-engine carrier=based fighter. The lone XF5F continued to be used for testing until it crashed in late 1944.

The Skyrocket was most famous as the plane used by the Blackhawks (a comic book flying group, first appearing in print in 1941) during most of the 1940's. In an alternate history, it might have been forced into production rather than waiting for the F7F to be developed. It did have some streamlining problems which were never really solved; hence it was slower than expected, but would have still been quite fast for a USN plane in 1942 (50 mph faster than the Wildcat and as fast s the Hellcat). Alternately, the Marines might have flown it, as they often got aircraft the Navy didn't want. As no armament was installed, the weaponry listed is a reasonable speculation.

The XF5F uses 89.5 gallons of aviation fuel per hour at routine usage.

Subassemblies: Medium Fighter chassis +3, Light Fighter-Bomber Wings +3, 2xLarge Weapon Engine Pods +2, 2x full three retractable wheels +0.
Powertrain: 2x895-kW aerial HP gasoline engines [Pods] with 2x895-kW props and 217-gallon self-sealing fuel tanks [Wings]
Occupancy: 1 CS Cargo: 16 Body

Armor
All: 2/3
Wheels: 2/3
Cockpit: F +0/30, B +0/30

Weaponry
4xVery Long Aircraft HMG/M-2 [Body:F] (300 each)*
* link fires all four

Equipment
Body: Medium radio receiver and transmitter, navigation instruments, autopilot, arrestor gear, 500-lb hardpoint. Wings: 250-lb hardpoint each.

Statistics
Size: 29'x42'x11'
Payload: 0.88 tons
Lwt: 5.07 tons
Volume: 100
Maint.: 35 hours
Price: $32,900

HT: 7.
HP: 120 [body], 120 [each wing], 120 [each pod], 12 [each wheel]

aSpeed: 383
aAccel: 4
aDecel: 17
aMR: 4.25
aSR: 2
Stall: 72

Design Notes
Design aSpeed was 359 mph and Stall 79 mph. The historical speeds have been used, as well as the actual wing area (305 square feet). Loaded weight was reduced 1.5%. Most of the unused body volume is treated as waste space.

Performance numbers do not include a bombload. The fuselage hardpoint can also carry a 58-gallon drop tank.

Variants
The XP-50 (1941) was a version built for the Army. The primary difference was that it used tricycle landing gear, requiring the nose to be extended past the propellor hubs. It also used turbo-supercharged engines, which started an engine fire leading to the crash of the lone prototype on it's maiden flight. The XP-50 was not really superior to the P-38 Lightning, which was further along in development, and the program was canceled. The XP-50 was the same as the XF5F in game terms, although the estimated top speed of 425 mph was never reached; given unexpected low speed of the XF5F, it might not have been reached.

[Anaraxes]

For the benefit of people like me that had never heard of this particular oddity:

http://aircraft-list.com/db/Grumman_XF5F_Skyrocket/74/

[Phaelen Bleux]

I always loved the look of this plane--it's ideal for an alternate history fighter squadron.

Are the bomb loads an estimate too, or where they part of the historical plane's intended design?

That should take care of the F#F series of prop planes, too!

[copeab]

Originally Posted by Phaelen Bleux

Are the bomb loads an estimate too, or where they part of the historical plane's intended design?

An estimate, based on the loads of the Wildcat and Hellcat. As best I can tell, no armament was ever actually installed in the XF5F.

[Anaraxes]

What particular advantages is this configuration supposed to have? Anything to do with aerodynamics over the wing?

It certainly would have a better view of the ground underneath than the more usual layout. I'm not sure if that's actually useful or not, since for bombing you probably want to see what's under your nose in front of you, not what's underneath you now.

[copeab]

Originally Posted by Anaraxes

What particular advantages is this configuration supposed to have? Anything to do with aerodynamics over the wing?

It gives excellent forward visibility, since there is no engine in the nose to block your view. Vision to the left and right is a little more restricted, although the Skyrocket sought to fix this by raising the cockpit a bit.

Also, being able to locate all the guns in the nose without the need to synchronize them is another advantage; you don't lower the rate of fire because of an interrupter gear for the prop (see p.W:MP8) and you don't need to converge the wing guns to some fixed range.

[Ulzgoroth]

Originally Posted by copeab

It gives excellent forward visibility, since there is no engine in the nose to block your view. Vision to the left and right is a little more restricted, although the Skyrocket sought to fix this by raising the cockpit a bit.

Also, being able to locate all the guns in the nose without the need to synchronize them is another advantage; you don't lower the rate of fire because of an interrupter gear for the prop (see p.W:MP8) and you don't need to converge the wing guns to some fixed range.

That sounds like advantages of wing-mounted engines. Doesn't so much explain the weird wing in front of fuselage thing.

[copeab]

Originally Posted by Ulzgoroth

That sounds like advantages of wing-mounted engines. Doesn't so much explain the weird wing in front of fuselage thing.

I can't explain that and I have yet to see a reason for it. It's possible it was done for center of gravity reasons.

[RyanW]

Twin engines also mean a little more security, and allows for counter-rotating props to eliminate torque effects, both concerns that interested the Navy in particular.

Originally Posted by Ulzgoroth

Doesn't so much explain the weird wing in front of fuselage thing.

Probably the result of some aerodynamic guesswork, or, as Brandon said, simply to put the centers of gravity and lift in the desired places.

If this thing had gone into production, I wouldn't be surprised if the production version was re-engined with the Twin Wasps that the F4F used historically. No real change in game terms, but the Twin Wasp was a few inches slimmer, and could mean a real difference in drag and thus airspeed.