Tuesday, September 26, 2017

Ch 9.5: MLG Access Close-Out

Thinking Ahead for Access

The last thing to do is close-out the top of the MLG area.  The plans have you leave two small diameter holes for inspection access to the MLG.  Since I routed the brake lines on top of the MLG, I needed slightly bigger holes to ensure I could get to the brake lines if needed.

Trace out the round corner rectangles using a template
So, rather than the plans round inspection holes, I built rectangular holes to give me more room.  I also wanted to build access hole covers to help muffle any noise coming from there.  With these, I can access any of the adel clamps holding the brake lines if I needed.

After following the plans to glass one side of the PVC foam, cut it to shape, and fit the pieces to the MLG bulkhead area, I traced rectangular panels symetrically on the port and starboard side of the horizontal panel.

View of bottom of panel with inspection panels cut out
at a roughly 45 degree angle before installation in fuselage.
These covers were then cut out with an angle inward from the top such that they would be self supporting when laid in place.  The top and side panels were then floxed in place in the fuselage.  Then, with the covers laid in place, I glassed the entire thing per plans.  Before it cures solid, I was sure to cut the inspection panel covers lose...it would have been much harder after cure.

After the the full panel is fitted and floxed in place and
inspection holes are taped up with box tape. 
After the MLG close-out was cured, I removed the panel covers that I had already cut lose and did some clean up work to make sure the openings for the inspection panel covers were nice an symetrical. Then I placed box tape all around the area were the inspection panel covers will go.

Glassed 2xBID over the inpection panel covers in place.

I placed the inpection panels in place with dry micro around the edges to help create a nice clean and gapless seal.  After cleaning up the excess micro that squeezed out the top, I glassed over the panesl with 2xBID extending past the edges of the panels approx 1".  I peel ply'd and allowed it to cure.

Inspection Panels, one trimmed up, one not, after being
removed after cure.

After cure, I popped them lose and trimmed the edges of the covers to approx 1/2" wide and cleaned up the excess micro.  I think the only thing I'll do to secure them is maybe use a dab of clear silicone sealent in a few spots.  That should keep them in place with no rattles.  In theory, I'll only need to remove them every once in a while to inspect the top of the gear or brake lines.

Inspection panels fit nicely !

Finished !  Nice MLG inspection panels that provide access while helping keep out unecessary noise.

Chapter 9 Complete...On to the first airfoil !

Ch 9.5: Brake Lines

SS Braided or AL Tubing ?
For this step, I'm only running the brake lines from the calipers, up the strut, and through the fwd MLG bulkhead.  At that point I'll cap them off and wait until a later chapter to run the lines up to the front where the resevoirs and master cylinders will be.

I chose to use SS braided PFTE lines (purchased from Pegasus Racing) from the calipers and up the strut because of the flexibility and movement of the MLG bow.  Once through the Fwd MLG bulkhead, I'll convert to lighter weight AL tubing to run to the nose where I'll probably convert back to SS braided to the resevoirs.

Here are links to what I used..
-3 SS Braided brake line
-3 PTFE Hose End
-3 Brass sleeves (Extra's in case I needed to redo a hose end)

The angle at the caliper end was such that I chose a 45 degree angle NPT/AN fitting and ran the line directly to the connection.  With the direct connection I didn't feel I needed to include a service loop in the brake line as I have some slack I can pull from up between the bulkheads if needed.  Don't forget to use a bit of pipe sealant seal on the NPT end...NOT on the AN ends.  I used Permatex thread sealant that you can get at most local auto supply stores.

1st attempt to run brake line...abandoned because there
was not enough room to secure the line without getting
in the way of the MLG access cover.
Routing Challenges:  My challenge was where to run and mount the braided line in the gear-well.  It needs to be run in a way so it won't chafe on any structure, and doesn't get in the way of my main gear cover.  I first ran it below the gear bow to a connection at the fwd bulkhead, and then planned to convert to AL tubing and complete the run to bulkhead connectors.  This would give me easy access to disconnect the lines if I ever needed to remove the MLG bow.  This would have worked, but I wasn't comfortable with how the line transitioned from the gear leg to down under the bow...I couldn't find a good way to secure the line without causing fit problems with the MLG cover.

So I rethought the routing and decided to run the lines up over the MLG bow and secure the lines with a few adel clamps.  The adel clamps are secured with Clickbond studs floxed to the MLG bow and secured with 2xBID.  The lines then go directly to the bulkhead connectors via 90 degree AN-3 hose end connectors.  This seemed to work out better and I can still access the bulkhead connections to remove the MLG if needed.
Final design.  SS lines, secured with adel clamps and
nylon split tubing for abraision protection in certain areas.
90 Degree AN-3 hose connectors attached
to straigh-through bulkhead connectors.

Next...Close out of the MLG Access and Ch 9 completion !