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I am at the point where I will be installing the 912ULS radiator on my model IV. But, I have covered and painted the aircraft and it seems that the photos in my circa 1997 manual show the radiator being installed under the cabin floor with the fuselage NOT covered but the photos showing the fuselage being covered do not have the radiator installed and I can't find where I missed instructions saying to install it before covering.
What should I do to install, cut the fabric and patch?
Only the bolts poke through the fabric on mine so the radiator goes on after the fabric and paint. Where are you at in Texas? We are getting an informal Kitfox/Avid club going here in Central Texas.
You still need some kind of support to bolt through for strength and to keep the top of the radiator flush with the bottom of the fuselage. Kind of like this... You can see through the fabric in this pic where my support is(I'm actually not using it because i decided to go with a differnt engine - HKS 700t). It's just a piece of cut down 1 x 4 epoxyed onto the bottom of the floor boards and it conveniently winded up being flush with the bottom of the tubes so the covering went perfectly over it. Drill through it where the radiator holes are and just have the heads of the bolts on top of the floor boards. Make sense? Sorry I don't have a better pic.
Unless you're able to pull up the floor boards easily you may have to cut and patch to install this. Although, you may be able to just drill through the fabric at the bolt mounting locations and use bushings/spacers instead of a full length board and only have to patch little circles. Not sure if this would be strong enough though since it relies only on the strength of the floor boards to hold the radiator.
I just checked my original construction manual and the way the radiator is mounted is to locate it toward the right side to minimize exhaust gasses passing through and so the mounting holes in the radiator are not over structural tubing then drill through the radiator mounting holes up through the floorboards. They recommend covering the floorboards with a piece of wood to reduce splintering of the floorboard. The radiator is bolted in place using large washers under the heads of AN526 10-32 screws and through tubular spacers to support the radiator at fabric level. Part numbers are mentioned but the hardware is readily available. This is the way I mounted it in my current project. I made the spacers of appropriately sized tubing. Having the fuselage covered is a non issue.
Lowell
Ahh, I see Lowel. So it actually is supposed to be mounted with spacers basically. Floor boards must be plenty strong enough then. I would go with what Highwing is describing... as it would require the least amount of destruction while being the easiest to finish out/reinforce the fabric at the bolt locations with simple small circle patches.
Thanks for the ideas. I can see that having the fabric there is not a big issue but had I known, I would have doubled it up where the holes are going to be. Now I'll just do it as a fabric repair of sorts.
Jerrytex, I live in College Station. Not too far from Bryan. Want to come and help me hang my engine?
Henry
Henry, I doubt the absense of the doublers will be an issue. I gathered from the instructions in the manual, that the location of the radiator is determined by the length of the aluminum radiator tubing wiith consideration to the exhaust flow and tube structure. With that in mind, it would be impossible to locate the radiator without mounting the engine. I guess it could be mounted and the radiator located, then removed, but it would add significant work and if it was an issue, I would think the factory would have mentioned it. I think what I would do is position the radiator and with someone holding it in place, burn the holes in the fabric with a soldering iron, then enlarge them with the iron for the spacer. That would melt and seal the fabric. This hole would be under the flange of the radiator so there will be no stress on the fabric there. Incidenally, the other day when I first responded, I went out and checked the stability of the radiator. It moves a bit, but is very firm in its mount.
Lowell