Fuel Tank Rebuild, new Trailer and Firewall rebuild
|the exposed pink foam shows the area I cut away.|
|cut foam and sanded inside laminate|
this shows what the edge looks like before dry Micro was troweled into the cut. Dry Micro was used, but that by itself has very poor adhesion properties. The technique here is to paint the surface first with raw resin and then trowel the Micro in.
2 plies of 8 oz fiber glass was added over the micro and exposed foam. Its only necessary to wet out only 1/8" beyond the edge. In approx 12 hours the epoxy will be cured to a semi hard state that allows easy knife trim. after trim, the edges can be slightly rounded over because the micro will be exposed.
This is a common technique that is used to finish out a structural edge. Sometimes, the foam us routed out flush down to a 1/4" and unidirectional roving is added in place of Microballoon, this would greatly increase the bending stiffness of the canopy frame. It is not required on an Ultralight however.
The next big job was to redesign the fuel tank, again this is a temporary solution. I am going to adapt an off the shelf polypropolyene tank, this will offer the maximum resistance to Ethanol. Its unreasonable to assume that pure gasoline will only be available in the future. I need to talk to Leon about revising the carb and Engine seals. I am really amazed what happens to epoxy when exposed to ethanol in gasoline. 20 years ago when I made fuel tanks similar to this for my old Wren, Ethanol was not used in fuel and I never had any issues. Because of this, I would NEVER consider buying a home built composite airplane that uses Mogas. Wet wings especially like the Lancair would be destroyed.
|existing fuel tank mold|
The rebuild started by laying up 3 ply's of 8 oz and one face ply of 120 glass in the existing mold. The mold was prepped with 5 coats of mold release wax. This mold is well seasoned, so 3 coats is sufficient
3 plies of 8 oz and a surface coat of 120 glass were laid up. All seams are overlapped a minimum of 1.5 inches
|Bottom surface mold form|
|lower surface mold form|
I added bondo to fill the foam surface, and then sand able primer over the top of the mold form. 10 coats of mold release wax was added and then a coat of spray able PVA water soluble release. After the mold was treated, I laid up 3 plies of 8 oz fiberglass and one surface coat of 120 glass.
|bleed air being added to aid the cure of the sloshing compound|
After the bottom surface was cured and released, I bonded a glass bearing block into the base of the sump. This will be drilled and tapped to accept some barbed nipples for the fuel line and primer line. I rough sanded the inside of the main tank and the bottom surface. I mixed up some epoxy and cotton Flox to a peanut butter consistency, its very important that this mixture have a shiny surface. I then bonded the upper surface to the lower surface. After the tank bond cured, I drilled a 3/4" hole where the fuel gauge will go and started the sloshing process. I am banking on this sealant to give me enough life of this new tank for the flight test program. I will constantly check the tank for signs of ethanol degradation
And Finally!!! The reason I was late in updating this blog was a trip I made to Pearson Georgia to South Georgia Cargo. I got a hell of a deal on a 24' enclosed cargo trailer. I will convert the interior into a camper and a hauler for my plane. The trailer was sold thru Allpro Trailer out of Florida http://www.allprotrailers.com/ Ask for Brian Robison firstname.lastname@example.org The price was $3800 base , but I ordered 5200lb axles, the final price came to $4300. After my buddy Ed and I picked up the trailer, we immediately headed north to Wilson, North Carolina where Ed bought a very nice Piper J3F cub project. Ed started a blog similar to this, http://nc35447.blogspot.com/2012/06/data-plate-confusion.html give him a visit sometime.
|Robins new Home away from Home|