XP-82 Almost Ready to Fly

[MIflyer]

May 23, 2018 - The restorers of a North American XP-82 Twin Mustang, one of the most unusual fighter/escort aircraft ever deployed by the U.S. military, are aiming to make EAA AirVenture Oshkosh 2018 its first public appearance to celebrate completion of an arduous 10-year restoration project.

The restoration project in Douglas, Georgia, began after aircraft restorer Tom Reilly discovered the complete airframe on a farm in Ohio. Reilly then scoured the earth seeking engines, propellers, and a multitude of other XP-82 parts to continue the restoration.

"The interest and enthusiasm for this restoration has been wonderful and gratifying," said Reilly, who has chronicled the restoration process online. "There is no better place than Oshkosh to make the first public flights of this aircraft, which is why it is our intent to complete the restoration and testing so we can be a part of AirVenture 2018."

The XP-82 restoration brings back a unique flying example of an aircraft designed late in World War II as a long-range fighter escort to accompany B-29 bombers for thousands of miles on missions over the Pacific Ocean. Based on the highly successful P-51 Mustang design, the XP-82 used twin fuselages and two specially designed Rolls-Royce, Packard-built Merlin engines to supply the speed, range, and armament needed for the task. Fewer than 300 of the airplanes were produced as the P-82, with all but five scrapped in the years after the Korean War as the military moved to jet aircraft.

"It has been decades since people have seen this aircraft type fly anywhere," said Rick Larsen, EAA's vice president of communities and member programs, who coordinates AirVenture features and attractions. "The return of this historic aircraft to the sky is a tribute to the vision and perseverance of the restoration team, and it's fitting that the group has AirVenture as a goal to fly this beauty before a huge, appreciative audience."

XP-82 Twin Mustang Project: HOME

 

[Fishboy]

That is fantastic!

 

[jetcal1]

I see he snuck in an update. Thanks!

 

[GregP]

Hope I get to see it in person sometime; definitely worth following.

Kudos to the team. Looks like a first-class restoration.

 

[vikingBerserker]

That's awesome!

 

[MIflyer]

My next trip up to GA I think I will swing by there. I'm sure the dog will enjoy it. Maybe she'll get to pee on the tires.

O'Reilly's used to be in Kissimee, FL. I flew over there in 1999 and took the tour. But Hurricane Charley came through in 2004 and all but wiped it out. At least the B-17 they had just rebuilt was saved.

I guess the XP was the actual one where they had to swap the engines from side to side to get it to fly.

Now, if they had told Fisher that the XP-75 idea was nuts and put them to work on building a Twin Mustang......

By the way, back in the mid-80's I decided to build a 1/48 P-82 using two Monogram P-51D's. It won't work!

 

[Shortround6]

By the way, back in the mid-80's I decided to build a 1/48 P-82 using two Monogram P-51D's. It won't work!

Didn't use enough putty,


and stand back far enough

 

[Capt. Vick]

Weren't they based on the "H"?

 

[MIflyer]

They had more in common with the H than the D - but purely in appearance. The guys restoring the XP-82 said there was about one part in common between the H and the 82 aircraft, and it was nothing major. And the canopy is that of the P-51F, or something like that

The P-82 fuselage was stretched as compared to a P-51D, by a lot. If you try to insert a plug in the aft fuselage of a P-51D model to reach the P-82 length you find out you can't do it that way. The fuselage tapers such that it radically changes shape over that added length. Talk about needing putty!

Fine Scale Modeler had an article on how to convert a 1/32 P-51D to a P-51H using a combination of Monogram and Hasegawa (I think) parts and I used that as a guide. The author joked about doing a 1/32 P-82 next and that inspired me to give it a try.

The P-82 differed from the F-82 primarily in keeping the Merlin engine in the usual P-51 installation. It worked great.

The F-82 changed to the V-1710 with the auxiliary supercharger such as used in the P-63. They switched because:
1. The Merlin required payment of $1500 each to RR for licensing.
2. And probably because the first SECAF was a former GM executive, and Allison was part of GM then (ironically, it is now part of RR).

The V-1710 gave them so many problems that virtually the entire production run of F-82's was shipped from Inglewood to the former Vultee plant at Downey, where they sat for years waiting for reliable engines. NAA tried fixing the V-1710, added antibackfire screens, and that seemed to help. The Air Force told them they were not an engine company, did not know jack about Allison's products and should stop insulting the engine company by fiddling with their products. Of course, by that time Allison was focused on jets and did not give a rat's rump about the V-1710.

 

[Gnomey]

Very cool!

 

[Kurtis Hooey]

The aircraft is surprisingly large when you see it in person. Quite an impressive machine. If anyone in the world can get this aircraft flying, its Tom.

 

[special ed]

Don't forget the one the CAF had when they were in Harlingen, Texas. Got to see it fly and photos. USAF took it back after it was restored and flying.

 

[chuter]

...
I guess the XP was the actual one where they had to swap the engines from side to side to get it to fly.
...

I've heard that about the plane not being able to fly with the propellers turning outboard, too, and yet most of the pictures of 887 in flight (see Wiki for instance) are with the props turning outboard. North American apparently flight tested the plane for a month before swapping the engines.

Wiki also states that the props were originally turning outboard (P-38 style) for better single engine performance which is wrong. Turning outboard gives better high-power, high-alpha handling and stall performance without a marked tendency for wing drop at the expense of single engine performance. Turning inboard moves the nose-up thrust-line (P-factor) inboard which, if only one engine is running, reduces the amount of rudder correction (and total drag) required BUT, because of the rotating propwash, increases the effective AoA of the wing outboard of the nacelle while reducing the inboard AoA making the outboard wing section the likely starting point for a stall making wing drop very much more pronounced.

 

[MIflyer]

The P-38 originally had the props turning the other way but they had a vibration problem and switched them to right turning right and left turning left to fix that. But the P-38 was a nosedragger and so the wing was not already in a nearly stalled out condition when in the three point attitude, unlike the XP-82.

Attached is an article I previously posted that provides remarks similar to yours.

 

[PStickney]

They had more in common with the H than the D - but purely in appearance. The guys restoring the XP-82 said there was about one part in common between the H and the 82 aircraft, and it was nothing major. And the canopy is that of the P-51F, or something like that

The P-82 fuselage was stretched as compared to a P-51D, by a lot. If you try to insert a plug in the aft fuselage of a P-51D model to reach the P-82 length you find out you can't do it that way. The fuselage tapers such that it radically changes shape over that added length. Talk about needing putty!

Fine Scale Modeler had an article on how to convert a 1/32 P-51D to a P-51H using a combination of Monogram and Hasegawa (I think) parts and I used that as a guide. The author joked about doing a 1/32 P-82 next and that inspired me to give it a try.

The P-82 differed from the F-82 primarily in keeping the Merlin engine in the usual P-51 installation. It worked great.

The F-82 changed to the V-1710 with the auxiliary supercharger such as used in the P-63. They switched because:
1. The Merlin required payment of $1500 each to RR for licensing.
2. And probably because the first SECAF was a former GM executive, and Allison was part of GM then (ironically, it is now part of RR).

The V-1710 gave them so many problems that virtually the entire production run of F-82's was shipped from Inglewood to the former Vultee plant at Downey, where they sat for years waiting for reliable engines. NAA tried fixing the V-1710, added antibackfire screens, and that seemed to help. The Air Force told them they were not an engine company, did not know jack about Allison's products and should stop insulting the engine company by fiddling with their products. Of course, by that time Allison was focused on jets and did not give a rat's rump about the V-1710.

I suspect that the real reason that the engines on the P-82/F-82 were switched from the V1650 to the V1710 was that at the end of the war, Packard stopped producing Merlins (As in August/Sept 1945, from examining the USAAF Statistical Digests. (1945 production is about half of the 1944 peak) It's understandable - Packard wanted to get back to its main business the war was over, and making cars was, after all, their real business. There were enough spare Merlins to support the P-51s already in service or in the pipeline (Most of which would be mothballed or scrapped), and tieing up Packard's factory space to make a small number of engines (The F-52 engine had enough differences that they had to be new-built) for an airplane that was proving to be several years out made no sense.
Allison was tooled up to build G model V1710s, didn't have any other business, and was being supported already in the push to get them up as a main jet engine manufacturer. Since the line was already in place, and the jets weren't being built there, it wasn't as much of a burden.
Consider that in 1946, it was well understood that the future was jets. Any reciprocating engines for combat aircraft (especially fighters) had reached their peak.
(Yes, P&W produced new engines for the Bearcat and the F4U-5 Corsairs, but they were adaptations of the C-Series engines that were in large scale production for other aircraft.)