Cowling Fit

[Capflyer]

I had a fustrating afternoon today trying to mate up my top and bottom cowling. The front around the spinner and air inlets do not fit together properly. I tried removing material by heavy sanding on both halves but the fiberglass was getting too thin. It seems that major modifications will need to be made to the lower cowling.

Have others had a problem with the fit between the two? If so, what was your fit problem and how did you fix it?

 

[rv6rick]

They do this on purpose as part of the 51% rule .

I've had the fit on Vans cowls off as much as 3/4" in the inlets of the old gell coat cowls. The newer ones I've done have been less than perfect...along the line of what you are decsribing. Just do 'whatever it takes' to make them fit. It's as simple as adding fiberlass where you need it and removing it where you don't need it.

Keep poundin' .

 

[robertahegy]

Sometimes heating with a heat gun and reshaping helps. Other than that, enjoy the many talents you learn building a kit. It's the educational experience.

Roberta

 

[RV7Guy]

Right of Passage

I found that if you clean up the lip on the lower cowl and the inside of the upper cowl you can get a pretty good fit. I used my Dremel with the sanding drum.

This is a Right of Passage to build one of these planes. Just like the canopy and baffling.

EVERYBODY has the same complaints on all of the glass stuff. I questioned Van's on why the glass is so crappy in an otherwise great kit. The response shocked me. "We hardly get any complaints, so it must not be a problem."

I firmly believe if everyone who has a problem (and everyone does) complains to Van's then they might, make some changes. It baffles me that Van's supplies such substandard glass accessories. Just doesn't make sense.

 

[RV_7A]

Mike,

If you have a really poor fit with the overlapped surfaces, cut them all off of the lower Cowling, fit the two halves together and lay up a nice new one on the inside using about 5 layers of 10oz. glass attached to the bottom Cowling. It will then be a custom perfect fit and all your frustrations are over.

-Jeff

 

[Lars]

Anyone have any experience with how the James cowls fit compared to the Vans parts?

 

[MrNomad]

Cowling 101

Jeff's right. Before I starting chopping my cowl, I spoke to Jeff for about an hour out of fear I'd have to tell the wife I just destroyed a cowl and needed the checkbook again.

But we gradually trimmed the nostrils enough to allow the center section to come together. Then we trimmed the sides of the center a little to bring even more of it together. My build partner Chet says "we're sneaking up on it" and that's about right. In other words, approach it gradually. Using Jeff's other good idea, Chet made a wooden backing plate for the spinner so there was no flex giving inaccurate measurements.

Make the bottom half fit first cause you can swivel the top to mate to the bottom. Remember that, unlike alum, you can easily add material back to the cowl so keep your WEST kit handy.

We trimmed the cowl using an el cheapo Harbor Freight 4" angle grinder. Because we are building a 9a, we cut the gear leg opening with a 1 & 1/8" slot at first (versus the 1 & 3/8" required opening) thereby leaving material for a second cut when we found the true center. You'll find that the flat side of the angle grinder blade will sand nicely.

Cutting an underside gear leg slot was a good idea too.

Last, Chet made me a 4' long board for sanding the bottom edge of the top cowl. He glued 80 grit paper to it. That edge establishes the paint line and it better be straight or the plane will look like ?*&^%$.

Our cowl is now mounted using a huge bungee cord. It's a good thing I didn't screw this up cause the wife hid the checkbook.

 

[Capflyer]

Thanks to everyone for responding. I get the impression that what I'm finding is pretty normal. It's easy to get spoiled with the kit because so much of it goes together well then you hit on this part which is a departure from the norm.

I like Jeff's solution and it's probably much easier to mold on a perfect fit than to keep fiddling with the existing bad fit.

 

[Bob Axsom]

Mine was fine

I never had any significant problem with my cowl. I had to build up the lower corners to fit the fuselage at that point and some minor fill where the honeycomb ended, etc. but otherwise OK. It looks great in its final form.

Bob Axsom

 

[Jamie]

I had a similar experience to Bob. The lower half of the cowl (just outside the inlets) were recessed about 1/8 inch back from the top half. No biggie...I just built it up and now, even unpainted, I have to point it out to people for them to notice.

Don't worry about sanding stuff too thin. Get it to the point that it fits then you can just lay some glass over the thin parts and you'll never be able to tell.

 

[mike newall]

We had to remove a lot of material from the lower cowl - I simply built up with layers of BID and West Eopxy as areas got thin.

A useful tool is a Vixen file - the teeth are large, but they don't clog and it cuts the composite well and has an excellent safety edge that enables a really neat corner to be achieved.

The front edges are still curled out a bit from the mold and will need filling and forming but within one work day, we had both halves on and touching evenly.

 

[RV_7A]

We had to remove a lot of material from the lower cowl - I simply built up with layers of BID and West Eopxy as areas got thin.

A useful tool is a Vixen file - the teeth are large, but they don't clog and it cuts the composite well and has an excellent safety edge that enables a really neat corner to be achieved.

The front edges are still curled out a bit from the mold and will need filling and forming but within one work day, we had both halves on and touching evenly.

THREAD HIJACK!!!!!!!!!


Hey Mike,

Did you get you plenum fitted and installed? Another local guy is using one and I was wondering how your install went. Always open for suggestions as to improve on my part.

-Jeff