Sunday, October 5, 2014

Ch 9.1: Main Gear Reinforcements (3 of 3)

Last But Not Least

Ok...down to the last strength reinforcements of the landing gear bulkheads.  This one beefs up the area between the forward and aft LG bulkheads themselves.   This is the area where the main gear bow will actually be installed.
Piecing together the template

The last reinforcement went so well using the template, I decided to try it again on this one.  I thought it might be the only way I was going to get the glass fibers running the correct direction all the way around.

I first pieced together a template using pieces of paper and tape.  I used a sharpie to mark the corner areas and planned to trace these on to the plastic before I wet the glass so I could get it positioned correctly on installation..

Since the area to be glassed has a major bend in it  (see right side of pic), I had to decide where to cut it in order to get it to lay flat for cutting the glass. It is mentioned in the plans that you'll have to cut the glass somewhere and overlap it or it will otherwise bunch up....but make sure you don't overlap on the hard points...these need to be flat.

Paper template
(as if looking down at the copilot's side).
Note the triangle cutout (top) where
the glass  will fold and overlap in the bend.
Looking around at other builder sites, I came across Charles Fernweger's builder site.   He showed a template that looked a lot like me a little confidence that I was on the right track.  He cut his from the front corner, where the three separate planes come together, diagonal up the 90 degree inside corner in the forward bulkhead.  When the template is laid flat, you get something like the top picture to the left.  The cut I made is represented by the open triangle.

Paper template
(as if looking down at the pilot's side)
Note the triangle gap is closed.
I closed this gap up with another piece of paper running horizontal until it met the other side of the open triangle like in the 2nd pic.  Note this is flipped as if for the other side.

When cutting the wet glass to shape, I made one cut from the location of the sharpie in the 2nd left pic, to the 4-way intersection.  The 4-way intersection is the corner where the three planes meet  (fwd upper bulkhead, fwd lower bulkhead, and fuselage side).  Now when I installed the glass, and it folds up, I had a side of excess glass to overlap onto the angled upper portion of the fwd bulkhead for a strong bond.  I hope that makes sense...EZ to do, hard to explain.

After the "all over" reinforcement is complete, there is one more 2xBID that goes over the hard points just like the other reinforcements.  Using the same process, I cut 2xBID 19"x 6" and laid it in from hard point to hard point.  EZly done.  (OOPS: The next morning when I completed the pilot's side I realized that I had accidentally made this lay-up with 3 ply's instead of 2...oh well...I guess a few extra once's wont hurt.)

Reinforcements Complete
Pilot's side, between the fwd & aft LG Bulkheads
Reinforcements Complete
Copilot's side, between the fwd & aft LG Bulkheads

All the fuselage main landing gear reinforcements are now done!  It's time to start working on the main gear bow itself.


Saturday, October 4, 2014

Ch: 9.1: Main Gear Reinforcements (2 of 3)

Center NACA foam between the
Firewall (left) and Aft LG Bulkhead (right)
(view is looking from right side of the a/c)
Adding strenght between the firewall and aft LG bulkhead.  

First the center foam piece is glassed w/2x BID (left).  This is the foam that forms the top side of NACA Scoop.  Easy enough.

Paper template used for second layup.
The sharpie lines mark the corners
of the layup area to help align it when installed.
Second, each side is glassed with 3xBID that wraps from the back of the aft LG Bulkhead, around the side, and on to the fwd side of the Firewall.  I followed the plans method for these pieces...make a paper template, wet out the glass on 3 mil plastic over the template, cut out the glass to match the template, install, squeegee  air out, pull plastic off. Voila!
Installing the glass this way made these layups pretty easy and were probably some of the best layups I've done...too bad they won't be visible as this area will end up being covered by the main spar.  One template will work for both sides but it is not symmetrical so remember to flip it over before you do the other side.  Peel ply from hard point to hard point as there is one more layup that covers that area.  You could do this layup and the next one all at one time, but with the tight space, I was afraid I would mess up the work I'd already done.  So I waited for this one to cure before going on to the next layup.

Pilot's side firewall (left)  to
aft LG bulkhead (right) layup
Copilot's side firewall (right)  to
aft LG bulkhead (right) Layup

The last layup in this area is another 3xBID that wraps from the firewall, across the floor, and up the aft side of the aft LG bulkhead hard point.  In total, this whole reinforcement places an additional 6 ply's of fiberglass over the aft gear hard points and the bottom engine mount hard points of the firewall.  Again, I peel ply'd the hard points and the edges of the glass which you can see in the pics.

With this area now protected, it's time to move on the "hell hole" between the forward and aft landing gear bulkheads where the main gear will actually be installed.