Bottom Installation

Once the bottom cures, installation is pretty straightforward. A block is glued in to support the foam at the landing gear bulkhead, then flox is spread on every mating surface, and the bottom is put in place and weighted down.

The plans say to hot glue a block to the forward side of the forward landing gear bulkhead, in order to keep the foam 1/8″ higher than the NACA scoop.  I glued this block in place before installing the bottom, but later realized that I shouldn’t have bothered.  The 1/8″ offset is to help in carving the joggle for the landing gear cover, but I later decided I would follow Wayne Hicks’ method, which doesn’t require a joggle.  If you are building your own, I would suggest researching the landing gear cover construction before you flox in your bottom.

Heather and I spread flox all over the mating surfaces, then set the bottom in place.  Unfortunately, I didn’t think to take any pictures of the weighted down bottom, but we used about everything heavy that we could lift!  I crawled underneath and wiped off the excess flox, but saved the taping for later.  It’s a good thing too, there is a lot of taping to do, and it would be very tough to do over your head while on your knees.

The next day I went to set about taping, and found we had made a mistake in the glassing of the bottom.   The front edge of the bottom is supposed to be rounded over, and have glass on the front face.  This face floxes on to the bottom of F-22, and you want to have a flox to glass bond there, not flox to foam.   The shear strength of the foam alone is not nearly strong enough, the flox would separate very easily, destroying the joint.

Fixing the improper glassing took a day of my working time.  First I cut the flox joint with the fein tool and a hacksaw blade, then I cut a 45 degree bevel on the corner with the fein tool, and sanded it round.

Once that was done, I pulled a sheet of plastic into the joint so that I wouldn’t get micro on F-22, and spread micro on the now exposed foam, using one of my mixing sticks.

Plastic barrier

I then made a 2-ply BID tape about 4 inches wide, pried F-22 off as far as I could, and laid it around the corner (very successfully, I might add). I then removed the plastic, spread flox in the joint just as I had done with the micro, and put a 2″ 2-ply BID tape over the corner and peel plied the joint.

Completed joint repair

As you can see in the pictures above and below, I used a couple clamps to make sure that the bottom stayed flush with the bottom of F-22.

Joint repair outside

The next day I removed the peel ply, trimmed up the fiberglass, and was quite pleased with how the joint turned out.  I proceeded to do about half of the joint taping, and half of the joint taping the next day.  I had the fuselage laying on it’s side for most of this procedure, and was amazed at how difficult it was to get the BID tapes to stick to the joints that were upside down.  Doing this with the whole fuselage upside down would have been a real chore.

Fuselage on its side for taping

Front joints

Forward side of instrument panel joint

It was quite exciting to see the fuselage interior come together like this.  Looking just at the inside, it’s starting to look like a plane!!

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