R

RV8R999

Well Known Member
I'm at the point in building the airbox kit where I'm supposed to extend the inlet by laying up some glass so as to allow the cowl to be removed vertically.

Wondering if you guys were happy with this solution and the quality of the seal? Any thoughts on how you would improve it if doing it over?

Thanks,

Ken
 
Not an -8...

...but I did build a -6A. The lower cowling was fabricated as per Van's instructions for the O-360 carb, vertical induction. The fabrication was not difficult, but the maintenance removal / install of the lower cowling is a pain.

If I were to redue this (still working the mental aspects), I would do everything as before, except I would not install the rubber gasket seal material between the snozzle and the inlet port on the FAB.

Instead, I would fabricate a seperate "sleeve" that would be inserted into the cowling snozzle and impinge into the opening of the FAB. To remove the cowling, this "sleeve" thing would have to be removed first. It would also need to be aerodynamically compatible with the existing snozzle design on the lower cowling.

Another item that somewhat hinders the removal / install of the lower cowling is the baffle material that surrounds the air intakes for the cylinder cooling. This and the item mentioned above both contribute to the difficulty in removing / installing the lower cowling.

Now for the time lines...it takes me about 4 min to remove the top cowling, and about 8 min to install.

It takes about 10 min to remove the bottom cowling, and 30 min to install. I do not have wheel pants or gear leg fairings installed yet.
 
There is no doubt about it - a tight fit is going to mean some fiddling during installation and removal. However, I built mine just the way Van's plans and instructions called for, and removal of the lower cowl takes a minute (after pulling the pins) and reinstallation maybe two minutes. Yes, the baffle seal material that seals the "snout" to the airbox has to be tucked in correctly, but that rarely takes me more than a minutes.

Paul
 
Ironflight said:
There is no doubt about it - a tight fit is going to mean some fiddling during installation and removal. However, I built mine just the way Van's plans and instructions called for, and removal of the lower cowl takes a minute (after pulling the pins) and reinstallation maybe two minutes. Yes, the baffle seal material that seals the "snout" to the airbox has to be tucked in correctly, but that rarely takes me more than a minutes.

Paul
Click to expand...

I absolutely agree with Paul. If you build it to plans it will work great. The things that will play a part in easing the removal of the lower cowl are: spinner gap(I have 3/16's in.), front horizontal baffle to cowl inlet gap(I have about 1/8 to 3/16's gap), the amount of overlap from the cowl seal material that extends onto the front baffle deck, and the gap between the aft end of the scoop extension that you're going to build and the airbox.

In a perfect world you would have all these gaps or overlaps match. To remove the lower cowl, you remove the pins then slide it forward against the aft face of the spinner bulkhead, the scoop extension is now clear of the airbox rubber seal, and the front baffle seal material is just brushing the forward edge of the front horizontal baffle edge. Then the lower cowl can be lowered straight down. On my aircraft, I probably have a little too much baffle seal material overlapping the front. I could either trim the baffle or the seal to make removal or reinstallation easier, but as it is I can do either in 30 seconds to a minute and not scratch the front, so it's now a D.F.W. item!
 
Question on this same issue

I'd like to weigh in on this question. We're building a 6A and received this photo from a friend reflecting how he did it.

fwf0030.jpg


The theory here is that, during installation of the cowl, the fiberglass cowl air inlet will fold the seal material as it passes over the airbox seal. Once the cowl is in place and past the lower seal, the seal will fall below the air inlet. The second piece of seal atop the airbox will stop the air from escaping above the box.

The problem I have with this design is that the incoming pressure at 150kts could lift the upper portion of the seal and air will leak rather than get forced into the airbox.

I'm ready for this step and look forward to comments on my friend's design.
 
Same result, easier cowl removal:

An alternate way to do it is to mount the U-shaped piece of seal fabric to the cowl and the flat top piece on the airbox. I did this and reinforced each with spring steel bands to keep them in contact with the mating parts. Based upon the wear patterns, it is clear that I am keeping them in contact.

This configuration allows the cowl to drop straight down when removing. Same for reinstalling the cowl.
 
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