Here's this morning's project. I started back on the tailgunner's compartment, as some material and sheet metal equipment arrived late yesterday afternoon. I know it's crazy how I go from one project to the next, but it keeps the job from getting monotonous. Sorry if this jumping back and forth is confusing to anyone.
The first step in making the lower portion of the tailgunner's compartment was to make a posterboard outline of the upper bows for duplication. Frankly, I screwed up with this particular project right from the start. I should have just made a form block out of wood or similar, so that each of the three bows would have been made from the same mold. The way I've done it here takes much longer and allows for more mistakes. Anyway, here's the process on the last bow...
I measured the length of the other bows and cut out a straight piece of bulb angle...
I just used the new shrinker/stretcher that we got yesterday, but discovered right away that just because you have decent equipment, with pnuematic actuation, it doesn't mean you can get in a hurry. I scrapped one piece within minutes of starting it. The key here is to
take your time!...
I used the posterboard pattern after each application of the shrinker. I worked from an index point in the center and went outboard, one half at a time. You can see here how it slowly starts to come to shape...
Here it is after the shrinking is complete. It is extremely time consuming to get this right and you have to not be afraid to just start over if you have screwed up too badly. I got lucky here and this particular piece has no imperfections from the pattern over .040". That should suffice for this installation...
After the shrinking is complete, I had to polish the marks from the shrinker jaws out of the aluminum. A scratch is a potential crack...
And here is the piece clamped onto the airplane. I'll get it clecoed into place and start on the lower sheet metal part of this project next...
Gary