P-61 alternatives

[Shortround6]

The Later SCR-720 mounted in a P-61
.

Please note that the dish could and did turn 90 degrees from the fuselage axis and is nearly there in the photo.

The radar used on the F4U, F6F and P-38M used a 19in parabolic reflector.

 

[XBe02Drvr]

Interesting thread. If I've got it right here's the definitive NP38 so far.
Somewhat elongated central nacelle with a boat tail extension aft and a longer canopy with a more gradual downsloping "fastback" to accommodate the RO. I read somewhere that NACA determined the P38's aerodynamics were negatively affected by the center nacelle's "bobtail" shape, but production commitments prevented a fix from being applied.
SCR 520 in the nose, with a mod engineered for 720 when it would be available. Bigger dishes enhance radar performance, but in practical terms antenna azimuths beyond 60° aren't worth the extra drag the larger radome produces.
Four 20MMs under the nose to minimize flash blindness. Moving the guns and ammo down and back along with the boat tail extension will shift CG aft so as much electrical and electronics as possible can go in the now vacated nose. Expendable ammo is now closer to the CG. The further forward the radar boxes are, the more separation they have from the cannons and their vibrations.
Night fighters don't "dogfight", but they do require a stable gun platform, so the additional keel effect of the longer boat tail aft of CG can be viewed as a gift, not a burden, and the existing flight controls should be adequate (boosted ailerons, of course). Redesigned larger "bolt on" rudders may be required for engine-out handling reasons.
This is all speculation, and given the time frame it would have been needed, the decision to proceed would have to be made long before the real world shortcomings of the P61 would become evident. On paper it would have looked like a world beater from the perspective of 1941-42. Nice exercise in retroscopy.

 

[Glider]

Quick and easy way to get a RIO in a P-38

Not a great place to be for a belly landing

 

[XBe02Drvr]

Not a great place to be for a belly landing

Well they're not Radar Intercept OFFICERS. They're Radar Operators, corporals and sergeants, so they're expendable.

 

[GrauGeist]

I hate to be the one to spoil the party, but that pod on the F-5 (P-38) was actually for Medivac...

 

[tomo pauk]

The 'Swordfish' P-38 modification would've been a good start, minus the wing appendices of course: link

 

[MIflyer]

The SCR-720 radar used in the P-61, late Mossies, and the P-82 was the best night fighter radar of WWII. It had a range of 10 miles and worked well even down to altitudes as low as 500 ft. AGL. Deliveries of the SCR-720 began in Nov 1942.

The Hellcat and Corsair night fighters were equipped with the APS-4. Production began in late 1942. It had a range of only 5 miles and was more adversely affected by ground clutter than the SCR-720.

The SCR-720 was much larger than the APS-4. Take a look at the pod that held that radar on the P-82; it was huge. There was no way to incorporate the SCR-720 in a P-38.

Comparing the P-61B and P-38M, the USAAF concluded that the P-38M had higher performance but for aircraft that both fighters were capable of intercepting the P-61 was superior. Both aircraft were found to have the same range, and the P-61's range was found to be inadequate in the Pacific.

 

[Glider]

I hate to be the one to spoil the party, but that pod on the F-5 (P-38) was actually for Medivac...

True, but it's still not good place to be for a belly landing

 

[Thumpalumpacus]

Interesting thread. If I've got it right here's the definitive NP38 so far.
Somewhat elongated central nacelle with a boat tail extension aft and a longer canopy with a more gradual downsloping "fastback" to accommodate the RO. I read somewhere that NACA determined the P38's aerodynamics were negatively affected by the center nacelle's "bobtail" shape, but production commitments prevented a fix from being applied.
SCR 520 in the nose, with a mod engineered for 720 when it would be available. Bigger dishes enhance radar performance, but in practical terms antenna azimuths beyond 60° aren't worth the extra drag the larger radome produces.
Four 20MMs under the nose to minimize flash blindness. Moving the guns and ammo down and back along with the boat tail extension will shift CG aft so as much electrical and electronics as possible can go in the now vacated nose. Expendable ammo is now closer to the CG. The further forward the radar boxes are, the more separation they have from the cannons and their vibrations.
Night fighters don't "dogfight", but they do require a stable gun platform, so the additional keel effect of the longer boat tail aft of CG can be viewed as a gift, not a burden, and the existing flight controls should be adequate (boosted ailerons, of course). Redesigned larger "bolt on" rudders may be required for engine-out handling reasons.
This is all speculation, and given the time frame it would have been needed, the decision to proceed would have to be made long before the real world shortcomings of the P61 would become evident. On paper it would have looked like a world beater from the perspective of 1941-42. Nice exercise in retroscopy.

You certainly put the advantages in better, and more technical terms, than I have, but that's essentially the basis underlying my suggestions. And yes, there's a bit of hindsight involved, but I've been known to climb up my own ass as well before, lol.

 

[Thumpalumpacus]

The 'Swordfish' P-38 modification would've been a good start, minus the wing appendices of course: link

That's what I'm talking about!

 

[SaparotRob]

What are those appendages?

 

[XBe02Drvr]

What are those appendages?

Some sort of airfoil cuff to enhance lift in the propwash stream and guarantee a root stall prior to a tip stall?? Some sort of a coolant radiator?? "Conformal aux fuel tankage?? An embryonic Boundary Layer Control system?? You never know what Kelly and the Skunks will come up with next. Watch the Billboard Hot 100 every week to find out!

 

[XBe02Drvr]

Take a look at the pod that held that radar on the P-82; it was huge.

Was that beast configured as a two pilot airplane with full flight controls on both sides, or was it a Pilot/WSO (or enlisted RO) configuration?

 

[swampyankee]

What are those appendages?

NACA was testing airfoils.

 

[MIflyer]

Was that beast configured as a two pilot airplane with full flight controls on both sides, or was it a Pilot/WSO (or enlisted RO) configuration?

The normal configuration for the P-61 is the pilot in the front, the gunner behind him in a seat that rotated 360 degrees with the turret, and the radio operator in the rear of the center fuselage. The only flight controls were in the pilot's position. Since the turret was either removed from late P-61A and early P-61B airplanes and in some cases replaced by fixed forward firing guns, one of the ETO units (421st?) moved the RO position to the gunner's position behind the pilot so to enable both men to acquire targets visually.

 

[XBe02Drvr]

The normal configuration for the P-61 is the pilot in the front, the gunner behind him in a seat that rotated 360 degrees with the turret, and the radio operator in the rear of the center fuselage.

My apologies for the ambiguous question. I was asking about the P82. The P61 has been discussed at great length here and I think, well understood.

 

[ClayO]

Comparing the P-61B and P-38M, the USAAF concluded that the P-38M had higher performance but for aircraft that both fighters were capable of intercepting the P-61 was superior. Both aircraft were found to have the same range, and the P-61's range was found to be inadequate in the Pacific.

Which says that maybe all they needed to do with the P-61 was leave off the turret and one of the crewmen from the beginning. Less weight for higher speed and faster climbing to altitude as an interceptor, or more room for an extra gas tank for longer endurance on patrol. Without the complexity and airflow problems of the automatic turret, the development time would have have been shorter, so maybe it would have been fully ready for service in early 1944 instead of needing further trials, undergoing second-guessing, etc.
Which crewman to leave out? They probably would have kept the rear guy, since he could operate the radar and keep an eye out for approaching fighters. That means that there would still have been the problem of the tail cone falling off, but maybe they could have solved that quicker if they could have focused more effort on it.

 

[Dana Bell]

The normal configuration for the P-61 is the pilot in the front, the gunner behind him in a seat that rotated 360 degrees with the turret, and the radio operator in the rear of the center fuselage. The only flight controls were in the pilot's position. Since the turret was either removed from late P-61A and early P-61B airplanes and in some cases replaced by fixed forward firing guns, one of the ETO units (421st?) moved the RO position to the gunner's position behind the pilot so to enable both men to acquire targets visually.

Actually, the gunner controlled the turret up to the 3:00 and 9:00 positions - aft of the the RO was to take over with his own gun sight and controls.

Cheers,



Dana

 

[GrauGeist]

Was that beast configured as a two pilot airplane with full flight controls on both sides, or was it a Pilot/WSO (or enlisted RO) configuration?

The P(F)-82 had dual controls so one pilotnwas able to relieve the other on long escorts/patrols.
The NF version, however, saw the flight controls removed from Starboard cockpit to make room for the RO's equipment.

 

[MIflyer]

For ferry purposes in the Pacific the P-61 did have a fuel tank mounted in location for the turret. Ugly thing, but I guess it was not used in combat.

Looking out behind was not a big deal; the aircraft had the APS-13 tail warning radar, so if they had relocated the RO forward to the gunner location they would not lose anything. P-61's in the Pacific were directed not to engage enemy aircraft in daylight but the pilots did not always heed that restriction.