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Top Cowl Inlet Ramps - when/how to install?

J

John Courte

Well Known Member
I'm a little confused by this step, which I'm rapidly approaching. The manual says something to the effect of installing the fiberglass inlet ramps with the cowl halves on and hinge pins in because with the ramps glassed in, the cowl is going to flex a lot less and may not actually allow the hinges to line up anymore.

I may be reading it wrong, but how in the known universe am I supposed to do an inverted fiberglass layup through the cowl inlets and another layup on the transition from the forward edge of the ramp to the cowl inlet itself?

I saw no mention of the acceptability of drilling/clecoing the ramps to the top cowl for the initial fit, then glassing that, which would minimize any drift in the hinges.

How did you install your fiberglass inlet ramps?
 
Upside down.

John, we glassed the ramps on our -6A with the upper cowl lying on a foam pad....drilled and clecoed the wet glass mixture.

After it dried, we removed the clecos and filled the lip with bondo and sanded smooth.

Best,
 
I don't recall seeing that instruction when I did mine but I just drilled the holes through the ramps where they attach to the top of the cowl first, then drilled and clecoed them to the front, then attached both cowl halves off the plane via the side hinge pins, dropped a light inside to illuminate the holes from the outside and drilled through the top cowl half into the illuminated holes. There was no problem, and it didn't feel like anything special.
 
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I've installed these ramps on a couple of RV's, and must admit that I didn't do anything special - just drilled, clecoed, and glassed them on with the top cowl sitting on the bench. I don't recall seeing any sort of detailed notes in the instructions - but then again, neither manual was "latest generation".
 
The instructions don't want you to warp the cowl while they cure. I just did mine a couple days ago with some pics on my site. To be safe I drilled some temp Cleco retaining holes in the inlets and top cowl when it was hinged in place. Then epoxied and set it back in place while it cured.

Careful as the epoxy can grab onto those Cleo's pretty hard. They came out for me though.

www.704ch.com
 
Thanks for the advice.

So basically: drill/cleco them for fit, glass them, and reinstall the cowl before the epoxy cures but after it's stiff enough not to peel away or drip down onto the (adequately covered and protected) engine?

What type of foam is that? Is that just Great Stuff?
 
Clecos

Touch the Clecos with Vaseline when fiberglassing. Keeps them from sticking
To the glass.
Bill
 
Foam is two part polyurethane from tap plastics. I would recommend that.

Of course make sure you sand everything and prep prior. But what you said is pretty much the process I used.
 
You must not let cooling air pass "under" the inlet ramps and bypass the cylinders.
Chads foam method is one way. Others have fabricated a complete fiberglass dam on one end or the other. I fabricated a partial dam to support the seal fabric near the spinner. It works great. Offered as an option. Builders choice obviously.

Link to my cowl page with the ramps
 
Yes, either way, but even with the foam, you need to do a fiberglass lay up. Using the foam for shaping purposes seemed like the way to go for me.

I have just finished mine, and it has come together pretty solid. Will update my blog shortly.

Good luck
 
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