U-2 Forward Fuselage Skins
Metal Work with the TM Technologies Air Power Hammer

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In 2013 Kent undertook a contract with Lockheed-Martin Skunk Works, Palmdale, CA to make a set of forward fuselage skins for a U-2, which was being upgraded.

Tooling arrives

The parts to be made required very precise tooling, which was made from machined foam. The first panels were small but had subtle shapes in the corners where two flat surfaces intersected in a radius bend. After making analytical paper patterns and then having several failures, I called Engineering, and they said, “We’re sorry Mr. White, but we have no idea how those parts can be made.” Hmmmm, okay. Time to make super-accurate patterns to .002” - .050mm. And then analyze exactly how the shape can go in and exactly the geography of the shape lays out on the surface. Aha, bingo. Although their one-inch trim requirements added a huge headache element to these problematic shapes, I was able to get them done to spec.
Materials

The skins were shaped from .032” 2024-T3, using the TM Tech Air Power Hammer. All parts were to be dye-chemmed and ultrasonically inspected before acceptance. The shaping was so severe though, that even though my work looked good under my magnifiers, I got an 8 x 10 image back after Lockheed’s inspections – with a huge crack showing. When I phoned their Inspection & Approval department, they laughed and said, “The crack was less than .050” (1.27 mm) but our cameras have 1000X magnification and it is on the outside edge of our one-inch trim zone. These skins passed and were accepted." Well, it was only one crack on four heavily-shaped corners, and they could trim it off …. what a relief.
Initial shaping

Kent hammers shape into the 2024-T3 material for the second set of panels.
Nitpicking

During this shaping process it was necessary to “nitpick” areas so that the whole surface was smooth and uniform. Here Kent works out tiny imperfections.
Final Fit

Once the shapes fit the tooling very closely, it was time to ship the parts for inspections and approval.
Third set of skins

Here another pair of skins being hammered into shape. You can see the different shape of this part in the tooling behind Kent.
Checking surface quality

The surface has decent reflection and quality (paint-grade).
Precision fit

Both skins fit tightly on the tooling (less than .020” anywhere).
Shop bottleneck

Tooling started to pile up in the shop as the job progressed.
More skins

Kent begins yet another set of skins for the job. As the job goes on the skins keep getting larger!
Surface reflection

Happily, the surface keeps looking good which is important to since the inspections find the tiniest flaws – but NO rejections, yet (knock on wood.)
Curve Ball

The job got a wee bit harder when a substitution was made in the design of one panel at the very end of the job. This final part required a reverse (saddle) shape. Even though the part was five feet long, Lockheed-Martin engineering decided to spec it for 2024-T0 .032” with cold working and then heat treating to T3. Kent doesn’t second-guess a company like Lockheed Martin, so he said “yessir” and got on it.
Heat Treat challenge

His contact at Lockheed (Dave B.) was a great guy to work with, despite the huge workloads he carried, so Kent jumped in and hammered out the new skin. He then wrangled with heat treat to get the LM specs in order, and ended up tying the skin down for the quench. Bingo! It came back needing only a few hours of correction, and the shape and fit were pretty right on.
Topography

The panel was not too large, so Kent was able to handle finishing it in the Air Power Hammer by himself. However making a large reverse shape like this takes extremely careful planning and keeping very accurate topography throughout the process. Once the topography was analyzed and marked out, Kent had to stay within his marked boundaries. Gradually the shape came in, and finally it all laid down tightly (exactly) everywhere. The final part had “regular” shape in some areas, with “irregular” shapes in other areas of the part. It was a very unusual shape when compared against the other pieces that were made.
Job completed

Whew! All the tooling is crated up and shipped back to Skunk Works, in Palmdale. Yeehaw. No rejections on the entire contract.