F28 and doublers installation

The F28 is the last bulkhead to be installed.

I started out by cutting the doublers to the dimensions shown in the plans.

I then sanded the edges round.

After test fitting them onto the fuselage, I noticed how the top inside corner was getting in the way of the fillet that was made with flox when the upper longerons were glassed. To have a proper fit, I decided to trim a 45 degree chamfer off the doublers.

 Showing the chamfer notch...

I then proceeded to measure the 5.9" from the forward face of the F22 bulkhead - this is where the forward face of the F28 needs to go (NOT the doubler!).

I then test fitted the F28 and made sure the notches were giving me a proper level fit.

Mixed up some flox and in it went...

I then applied flox onto the doublers and installed them as indicated in the plans.

A few clamps to hold everything in place during cure...

Eh, a few more clamps... why not?

After cure, I sanded everything flush and got ready for the 1 ply BID that goes over the doublers.

Mixed up some dry micro and filled any voids....

I then prepregged 1 ply of BID and installed it - making sure to overlap onto the F28 bulkhead, top longeron and fuselage side.

A few peel ply strips to have a nice smooth transition...

After cure, I removed the peel ply and trimmed the edges using the vibrating multitool and the dremel.

And there you have it! F28 and doublers are installed!


Ron said...

Ary, again outstanding effort on the entire body of work. do you know if, other than possible cost,if honeycomb core could be used rather than foam? I know it would probably be more work but would there be any value to its use?

Ary said...

Hi Ron,

I don't think there would be value in it. One would have to do a weight analysis to see how much of a difference it would really make. Also, I'm not sure about its physical properties. A lot of analysis goes into designing a composite structure - so one would also have to see if it would still contain the same physical strength (both in shear and normal stresses). My gut feeling is any benefit you would gain is not worth the work required to re-calculate the design of this already proven airplane design.