Wednesday, April 30, 2014

April XP-82 Twin Mustang Restoration Update

 April was a great month with lots of good progress.

Wings/Sheet Metal
The men have been making excellent progress on both wings. The majority of the skinning and riveting on the forward top and bottom of the right-hand wing is now completed. All of the in-conduit wiring, pitot, and aileron cable tubing, and drop tank pressure and feed lines are now pre-installed in the right-hand wing. 

The final structure set-up on the left-hand wing has now been completed and the preliminary dimpling, counter-sinking and skinning of the top skins is progressing.

Due to the spring/summer temperature changes, the crew must check the washout, sweep and dihedral each morning when it is cool and each afternoon as the temperature increases 30 to 40 degrees. The wings are fixtured to not allow the temperature variations (expansions and contractions) to change the set-ups.  We must maintain the exact dihedral and the washout measurements to within one-twentieth of one degree so that the aircraft will fly “hands off”. 

With the dihedral and washout locked in to those degree settings, the final reaming of the .3735 lower wing-attach bolt holes on both wings has now been completed.  (A reamer is a precision cutting tool to bring a reduced-drilled-size hole out to final size. A drill bit will not drill a precision hole.)

On wing-attach angles, nut plate channels are used where one cannot gain access to the wing-attaching nuts to tighten them. North American, however, installed nut plate channels with nonstandard spacing on the upper sides of the lower attach angles located in the fuel tank bays. None of the original channels we had were repairable, and the uneven spacing made it impossible to purchase a standard nut plate channel from any supplier.  Thus we had to make up all the new nut plate channel strips.

Wing attach nut plate channels

Left-hand lower wing attach angle with nut plate channels riveted on.

One of our sub-contract machine shops is now heavy into completing the aileron sectors and mounting hinge points for both wings.

Canopy, Windshields and Glare Shields
The second canopy glass has now been fit into the repaired canopy frame. It took parts out of all three damaged canopies that we had to repair and complete the right-hand canopy frame

The damaged and corroded right-hand canopy frame

Repaired right-hand canopy frame with fitted glass

The right-hand glare shield was another story.  The restoration to the left-hand one was relatively simple as it was basically undamaged.  The damaged right-hand one required a major amount of repair and splicing together many repressed parts to complete an airworthy unit. 

Munched right-hand glare shield

Newly repaired right-hand glare shield

We have completed both center 1.5” thick, bullet-resistant windshield glasses.  We are in the process of forming our four windshield side glasses to fit the windshield bows and glare shield frames. 

 New 1.5" thick, bulled-resistent windshield glasses

Throttle Quadrant Cables
One of our men is currently completing all of the cable hook-ups that simultaneously link both quadrants together through cables that run through the center section from one cockpit to the other. 

The original throttle quadrant

Throttle quadrant cable hook-ups with detail (below)

Inside Skins for Outboard Gear Doors
Pat Harker (F-82E, Anoka, MN) has built the tooling and has successfully pressed one set of skins for his serpentine-shaped outboard gear doors. He has offered to sell us a pair for our project.  Thank you, Pat!

Heat Treating
We brought another batch of parts that needed heat-treating to Thrush Aircraft in Albany, GA, to be brought up to T-3 condition. The amount of special help Thrush has given us has been priceless. Thank you, Thrush.

Thrush Aircraft's new 710P
"Unmatched power.  Unquestioning control"

The Katz
They took two weeks off to go to Daytona for Spring Break.  More on the Katz next month.



  1. I still have countless questions about this amazing aircraft. How many flight hours did the longest-serving airframes reach? What sort of problems did they develop over time? You mentioned magnesium aileron attach fittings that were prone to cracking; what other high-fail items or systems caused headaches? If you are too busy to answer all these questions or reluctant to encourage me to ask hundreds more, can you recommend reading material?
    all the best,

  2. Sean … thank you for your questions. I believe I read somewhere, where I don't remember, that one Korean War survivor had just under 1,000 flight hours. The magnesium trim tab fittings did not crack due to inflight stresses, but to the electrolysis between the steel pressed-in bearing/attach bolts and the magnesium fitting. The only known high-fail items were the Allison-powered F-82 series with continuous engine problems. The Merlin-powered P-82s were very dependable. We cannot discern from the blurred data card the amount of total hours our XP-82 had flying for NACA. The numbers that we can read, which are not in chronological order, are in the 5,000+ hour range, but very confusing as some of the numbers are dramatically higher on a previously recorded dates than the entries on the succeeding dates. I question the 5,000+ figure which seems to be dramatically high considering the aircraft was a research and development test bed for approximately five years.
    Tom Reilly

    1. Hi Tom,
      Thanks for your answers. My mechanic's curiosity is almost limitless. Looking at the phenolic blocks clamping lines, I am reminded of my years maintaining USAF Sikorsky H-3s. A one-time inspection of these clampings revealed a heap of seriously chafed hydraulic lines. Access was pretty easy as they were in the cabin ceiling with only dripcatchers to remove. I realize helicopters are a whole 'nother beast when it comes to opposing forces and airframe flexing and twisting.
      I await each monthly newsletter with great interest, and am very thankful that you and your team share so much of this fascinating project. It is also great how you recognize all who contribute time, equipment, and materials to your efforts.
      all the best,

    2. Hello again. Are you also manufacturing the windscreens?

    3. Sean …

      On some of the close-up pictures, one can see the thin rubber anti-chafe strips that are glue-installed in between the phenolics and tubes.

      And, yes we are manufacturing the windscreens.

      Thank you again for your interest in our aircraft.

  3. I have watched your project with great interest and finally decided to write and say Well Done. My father was an F82 pilot during the Korean Conflict and flew the all weather version. He has since passed on and is buried at the end of a run way believe it or not. His plane was Ain't Miss Behaving and had the same picture that you can find on the internet of a squadron flying, in a frame on the wall in his home. I sure would love to be there when your plane and the other F-82 finally make their flights, again. Take Care, Mark Harp

  4. Thank you for your Dad's service. He will be looking down from above when she takes that first flight---again.
    Tom Reilly and the XP-82 Crew.