One was fantastic, two would be ...?

[pampa14]

Developed shortly after World War II, the Twin Mustang was not involved in the conflict, however, as it would have been his performance against the German fighters? The P-82 had anticipated the end of the war? What do you think? The link below provides an interesting report about these questions and an extensive collection of photographs, some rare and unreleased for me. To see the full report and the photos visit the link below:


Aviação em Floripa: North American P-82/F-82 Twin Mustang


Best Regards!

 

[Kryten]

I would think the roll rate would be poor compared to a P51, and it's handling and weight must be a real issue, that and the huge profile making it easy to spot?
Shudder at the thought of taking that to war.

 

[tomo pauk]

Developed shortly after World War II, the Twin Mustang was not involved in the conflict, however, as it would have been his performance against the German fighters? The P-82 had anticipated the end of the war? What do you think? The link below provides an interesting report about these questions and an extensive collection of photographs, some rare and unreleased for me. To see the full report and the photos visit the link below:
....

(sorry, Denniss and dougsboy)
And just where is the report??

 

[drgondog]

The XP-82 performance closely matched the P-51D, except it was faster and climber better at same RPM/Boost.

At 20000 pounds combat weight full internal fuel (575 gallons) the W/L was about 47. The 1650-11/21 developed 1405 Hp at 25000 feet, but capable of 1780 Hp at 22500 feet at 90" and 1860 hp at 19,400 at 90" and 2270 Hp at 4000 feet at 90"

By contrast the P-38L with full internal fuel 410 gallons, full combat load was 17,700 pounds and engines at 60" (Max Combat Power) at 26500 feet generated 1600 hp.

At max combat power the comparisons between the XP-82 (with Merlin engines) and P-38l (or K) were
P82 WL = 47, Hp/GW@ Max Combat Power = 2x2270/20000@90"= 0.277, carries 575 gallons of internal fuel. The P-82 HP and max Combat power at 22500 feet = 2x1780/20000 @90" = 0.178

P38L WL= 54, Hp/GW@Max Combat Power = 2x1600/17700@60"= 0.181, carries 410 gallons of fuel. The P-38L HP and max Combat Power at 26500 feet=2x1600 Hp/17700@60" = 0.181

The engine/boom mass combination for the P-82 is a smaller distance from Center of gravity than the twin boom P-38, has no center gondola and a shorter wing span (51 vs 54 feet). It should roll as well or better than the P-38 and accelerate, turn and climb better. It will certainly Dive better.

I have not seen maneuverability related data but the wing loading and Power ratios strongly suggest a significant advantage in all aspects from Drag and overall agility plus guaranteed speed and climb advantage based on the hard data.

The P-82 was much faster

 

[GregP]

The P-82 was a later design and much had been learned aerodynamically and practically since the XP-38's original design. I'd be a bit disappointed with North American if the P-82 wasn't a bit better than the P-38 in at least most respects. I'm not too sure the P-82 was the best North American could do in the twin-boom layout, but the P-51 had some significant design improvements over the original XP-38, at least as far as aerodynamics go. So a twin made from P-51 basic layout SHOULD have been an improvement and proved to be so.

No real surprise. Actually, Lockheed could have done better, too, if allowed to develop the P-38 some in 1942 - 1943 ... but the Super P-38 really didn't show that to be true, did it?

What surprises me is that the Germans had such a hard time coming up with a good twin engine fighter.

The British Mosquito was no P-38. That is, not a fighter to combat other fighters as well as the P-38. But it was superb as a light bomber, recon, pathfinder and night fighter. It could hold its own or get away with sheer speed ... usually. The Japanese had some pretty good twins. The US has the P-38 and P-61 that was a really good night fighter, if a bit late.

The Bf 110 was an altogether pleasant airplane to fly and had very good flying characteristics, but it really wasn't anywhere near a match for either the P-38 or the Mosquito. Neither was the the Me 210. The Me 410 was better, but still was too heavy and ponderous for a fighter, though it flew and handled well for the weight and power, and had a really good punch in its guns.

The Bf 109 and Fw 190 were as good and many times better than all counterparts, but the German twins were always a few steps behind in performance in their originally-intended roles, though they WERE adaptable. The best German twin for my money that was made in any significant numbers was a Ju 88, and it wasn't exactly a svelt twin engine fighter. But it certainly did everything asked of it and more. But they had no counterpart for the Mosquito or P-38 directly. The closest I can think of would be the DB-powered Focke-Wulf Fw 187 that was rejected by the political-if-not-exactly-good RLM.

 

[Peter Gunn]

My question would be flying from one side or the other, initially I'd think it would be disorienting but I've read a couple of the Korean combat reports and it seems that wasn't really an issue, or perhaps training helped with that?

I always felt that the P-82 had some great unrealized potential, nothing against the Allisons but I seem to remember the Merlins performed better, or is that an urban myth?

I too did not see any report.

Although I think it was about the 15th picture down where there's a batch of them being assembled and there's what appear to be a pair of early Fury's being put together as well. Neat period shot of a very transitory time in aviation.

 

[drgondog]

The major differences between the two fighters were twofold. First, the aerodynamics of the wing. The NACA 66 series was used both on the P-51H and the P-82 and was cleaner than the NACA/NAA 45-100 and FAR less drag than the NACA 23016.

Second, the layout of the P-82 was a better platform for growth, both in mission (ultra long range escort, fighter bomber, night fighter, day/night interceptor). It was not tested enough in Korea to definitively state that it was as good a 'dogfighter' as the P-38 but the metrics of the airframe point to better maneuverability for the P-82 (with 1650-11/21).

The advantages are significantly less with the Allison 1710-143/145 because Allison never effectively fixed the high boost detonation - and according to Schmeud, didn't care to invest in the fix. As a result, the Allison which was rated at 90" with WI never ran past 61" in service with USAF.

 

[Peter Gunn]

I imagine then that Allison was probably more interested in developing jets than any further work on the 1710, pity, I always felt the V-1710 was a pretty damn good engine that never fully realized its potential.

Thanks for your response, I'd still, just looking at it, think it would take a little bit of adapting to be sitting a bit off the centerline and all, but apparently that wasn't an issue.

I would imagine that with the endurance it had, pilot fatigue could become an issue, even with splitting the flying duties.

 

[GregP]

I used to fly RC aircraft and sometimes flew with Col. Bob Thacker, of P-82 fame. According to Bob, it felt like it would roll around his canopy, and it didn't make any difference which canopy he sat in at the time. He said that took many P-82 pilots pleasantly by surprise as they expected to feel like it was rolling about the center of the wing.

 

[drgondog]

I heard the same thing - that there was nothing dis-orienting about rolling in a P/F-82

 

[GregP]

That being said, I think it was a very good fighter for a piston twin. It just came near the end of piston fighter lifetime and so had little chance to make a mark. Had it been introduced in, say, 1944, it might have been a totally different story.

I know, the dreaded "what if," but I think the P-82 had great potential and, during the war, there would have been no political pressure to move away from the Merlin engine.

 

[tomo pauk]

The P-82 with war-time 2-stage V-1710 would've been a pretty useful bird IMO.

 

[Shortround6]

Kind of depends on when and if you could get intercoolers into the plane.
The first P-63C with the E21 engine wasn't delivered until Dec 1944.
The E11 engine was great at sea level ((1800hp) using water injection but even using water injection power fell to around 1500hp at 15,000ft and a bit over 1200hp at 20,000ft. This was the engine used in the P-63A with first delivery of a production plane in Oct 1943.

 

[tomo pauk]

Hopefully with F series engine of similar power would allow for some 420-430 mph? Plenty enough for 1944, very useful for 1945, especially against Japan, by what time something along the lines of V-1710-121 would be in service use (was flight tested in March 1944, at 3200 rpm and 75 in Hg). With 1200 HP at 25000 ft, no ram, we'd be looking at 450 mph?

Versus P-38, it would have much more fuel aboard, far less problems with compressibility, less pilot fatigue.

(unfortunately, in the Vee's the altitude power of the -121 (F28R) is way over-estimated at, IIRC, 1600 HP at 26000 ft - it is ~1600 HP at 17000 ft)

 

[drgondog]

Tomo - the 1710-119 was the primary engine for the XP-51J and experienced the same issues with speed density carb as the 1650-9, to the point that WI was not effective. It remained ineffective through August 1945 when testing was suspended. The 1710- The 121 IIRC was the same basic engine as the -119 and -143/145 and the engines finally solved the carb/boost control issue but not backfire/detonation.

 

[tomo pauk]

The -119 was featuring intercooler and 'speed density pump' instead of carb, the two features absent on the -121. The -121 was featuring less power, but also less of issues - basically 'old tech' that worked, vs. 'hi tech' that had problems.
The counterpart of the -121 in the P-63E, the -109 (E22) was also trouble free.

 

[BarnOwlLover]

Sorry to resurrect this thread, but I previously asked about roll characteristics about the F-82, and whether it rolled around the axis of one fuselage or another (depending on where inputs originated) vs the centerline of the wing. Now I'm confused as to what is true based on the previous comments about that. Especially after asking about this previously elsewhere that seemed to hint that it rolled about the the centerline of the wing.

 

[GregP]

The major differences between the two fighters were twofold. First, the aerodynamics of the wing. The NACA 66 series was used both on the P-51H and the P-82 and was cleaner than the NACA/NAA 45-100 and FAR less drag than the NACA 23016.

Second, the layout of the P-82 was a better platform for growth, both in mission (ultra long range escort, fighter bomber, night fighter, day/night interceptor). It was not tested enough in Korea to definitively state that it was as good a 'dogfighter' as the P-38 but the metrics of the airframe point to better maneuverability for the P-82 (with 1650-11/21).

The advantages are significantly less with the Allison 1710-143/145 because Allison never effectively fixed the high boost detonation - and according to Schmeud, didn't care to invest in the fix. As a result, the Allison which was rated at 90" with WI never ran past 61" in service with USAF.

Joe Yancey ran a G-series Allison at Reno in a Yak-9 at 110" MAP. Grahame Frew owned the aircraft and flew it. Ran great. Won Bronze. Won Silver. The engine never missed a beat and STILL runs great.

I'm not really sure what the high-boost detonation issue was and, since Allison never got it sorted, perhaps they weren't sure, either. But WE surely didn't see it at Reno. Of course, the density altitude was likely somewhere around 7500 feet during the race and that might not be in the envelope where the G-series engine had an issue. We never took it to IFR altitudes.

 

[GregP]

As we said above, the 2 pilots of a P-82 both felt as if the aircraft was rolling around their seat. That said, it is logical that it was actually rolling around the centerline and they just weren't far enough away from centerline to feel any effects from it ... logically anyway.

I doubt you will find a technical discourse on it, but we DO have pilot notes saying that both pilots felt as if it was rolling about their position. That's about the extent of what we have in writing, as far as I have been able to dig up.

If anyone has more, please post or link to it.

Cheers.

 

[Shortround6]

It would certainly seem to me (not a pilot or aircraft mechanic) that trying to rig the aircraft controls (mainly ailerons?) to use different deflections per side depending on which set of controls was used and trying to figure in the different response at different speeds would have been a nightmare of both design and rigging.

Maybe it could be done with a modern flight control fly by wire system with computers between the sticks and the control surfaces ???
But in 1945-48 with cables and/or push rods?