Making fairings for struts

[gizmos]

I made enough for a couple sets, still have to cut tubing slot

[Av8r3400]

What about covering with fabric instead of fiberglass?

[gizmos]

I like to glass them. It make them stiffer than fabric and will not dent. I use west system epoxy, I have made numerous r/c plane molds. I made a 110in long sr71. The trick is to keep it light by using paper towels to dry excess resin off.

[gizmos]

One strut ruffed in

[gizmos]

Foam on, first coat filler

[HighWing]

Here is another idea from the Lancair crowd. Lay a piece of polyethylene sheet on a flat surface. a bit wider and longer than the fiberglass. Lay the glass on top of the plastic and pour on the resin. Spread to saturate the cloth and lay another piece of the Poly on top and squeegee as much of the resin out of the cloth as you can. Brush the styrophone very lightly with the resin using a brush. Remove the top poly sheet and using the bottom one as sort of a handle, carry it to the foam. Press the cloth to the foam and remove the final layer of polyethylene. Smooth with a gloved hand.

The image shows the technique for the horizontal strut fairings - very light.

[Dravenelle]

just a question

why don't you make a mold when you have
the plug ( foam shape)?

if you make a mold, you have a full composit
fairing... not foam inside?

just my 2 pen

David

[gizmos]

You need something to hold in place. You could make a mold and put foam in spots. How many times have you seen people leaning on struts getting in and out of plane.

[gizmos]

I used 3m contact to attached fiberglass cloth to struts before I apply epoxy, west system epoxy is the best

[HighWing]

just a question

why don't you make a mold when you have
the plug ( foam shape)?

if you make a mold, you have a full composit
fairing... not foam inside?

just my 2 pen

David

I did exactly that on my first Model IV. But removed them after some BAD advice from a hangar neighbor - something he said about the materials I used being corrosive. The last place I wanted corrosion was on the lift struts. FHIW, I made up a test section on some 4130 and after 15 years no corrosion - even aganst the clean sanded metal section. Not knowing for sure, I removed them and used the PVC.

What was mentioned regarding their security and stiffness is a factor unless you placard - No Push and cross all your fingers. I have very thin aluminum fairings on my landing gear - .008". At the Arizona Desert Fox fly-in a guy leaned against one side with his leg looking in the cockpit and pushed a wrinkle into it. I made them raplaceable and have patterns so replacement was not a problem.

For the lift strut plug mold, I used a length of the extruded PVC. It was riveted to a long piece of sheet aluminum on the trailing edge to eliminate the overlaps of the glass sticking together. The ridges were sanded off and filled,then smoothed and painted. Once the fiberglass skins are cured, it is easy to trim excess to width with a carbide blade in a table saw. Once installed on the lift struts, I drilled holes at intervals and injected two part Urethane foam as a stiffener - it was the foam that the hangar neighbor didn't like (corrosive?). The foam exerts a lot of pressure as it foams up so you have to support the exterior surface of the fairing skins to prevent some parts of the fairing resembling a Greatest Loser Contestant. The weave still has to be filled and sanded, but it is not that big a deal. One of the real nice things about glass is that finishing the "V" becomes pretty easy. I would guess about a 7 or 8 lb. weight saving total