Sam James Cowl - planning some corrective surgery

I have a pretty bad misalignment at the air intakes of my James Cowl, despite trimming very carefully around the firewall and the side seams - and getting good results.

The extent of the misalignment can be seen in these photos (I wasn't able to rotate the first one - sorry)
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The fix I have in mind is fairly radical so I would appreciate some peer review before I go ahead. I intend to make a cut along the black Sharpie line and pull the top half of the air intakes into the correct position where I will clamp them. Then I will lay up a strip of fiberglass over the resulting gap and when it has hardened, I will repair the gap from the inside. Finally, i will grind off the excess fiberglass from the outside.

Once the cut is opened out, I will no longer have a smooth curve across it. So there will be some extra grinding and epoxy filling required to fix that.

Does this seem like a reasonable plan? I would appreciate any comments or better suggestions and I promise to report back with photos of how it eventually turns out.

I'd be more inclined to move the bottom one back. You might be able to add a slice to the bottom and use a heat gun to position things. Don't Cut it off all the way. Then just clean up the crack.

Example...when facing the cowl, the one on the left. Cut the bottom cowl just below your black marker. from the 9:00 position in an arc to the 4:00 position with a 1/8" cutoff wheel. Heat the glass and press the loose ring into place. Clamp it an let it cool. You may need to make a pie shape cut.

I would call Sammy/Will back up and tell him of the problem and have him send you another one. They are pretty good about that.

Scott

hydroguy2 said:

I'd be more inclined to move the bottom one back. You might be able to add a slice to the bottom and use a heat gun to position things. Don't Cut it off all the way. Then just clean up the crack.

Example...when facing the cowl, the one on the left. Cut the bottom cowl just below your black marker. from the 9:00 position in an arc to the 4:00 position with a 1/8" cutoff wheel. Heat the glass and press the loose ring into place. Clamp it an let it cool. You may need to make a pie shape cut.

Click to expand...

cowling

Im working on some sim problems sending PM.

Loman,

Hold off on the hack job.

I aligned the front and then put the back in.

The heat gun will help you.
I cut some of the spinner (inside) and this helped.


Patience

Great replies - thanks

Thanks for the feedback guys. Some further responses/info:

I was not intending to cut all the way across the front of the top cowl. What can't be seen in the photos is that the Sharpie lines do not meet. A three-four inch section over the middle would not be cut.

Two things about cutting the bottom instead of the top: Firstly, the top half of the 'spinner ring flange' (hard to find a good name for that but you know what I mean) is inclined slightly backwards and only contacts my spinner template disk properly at the top. Maybe you can just see the gap in the top photo (3/16 in. at the bottom). My planned nose job would fix this also. The bottom half of the ring is flat against the disk. Secondly, if I cut the top and open a gap, I have only one cut to worry about. If I cut the bottom, I have to cut two sides of a pie and I have to get them perfect so that the gap is closed very precisely.

I will indeed ring the 'James gang'. Note however that I am in Ireland and, from memory, they don't really 'do' internet/email. Is that still the case? It means I can only describe the situation verbally. The other thing about that is that any replacement cowl has to be sent a really long way and it will take a long time. I wouldn't ask for that without really trying to fix things here first.

The aft edges and side seams are all cut and match-drilled to hinges already so I have shot my bolt as far as starting at the front and working back. Besides, I was working with the 'spinner ring flange' (what is that called anyway?) firmly attached to my plywood disk. By the way, that plywood disk has been positioned 1/4 inch aft of the actual spinner aft edge to account for the required gap. So this is a mis-alignment between the air inlets and the spinner ring flange ("SRF"?) on the top half of the cowl only.

This is too big a job for heat. I would have to apply it over too big an area with very complex curves and I could not be sure of reforming it all nicely when it gets soft.

"Patience"? - Don't worry, I am not nearly at the end it and I still think this is fun.

Do a search of

"DanH" as he has written and demonstrated more on this topic than the law allows.

I think that Will James is the cowl guy while Sam does the plenum. If Sam shows up for breakfast tomorrow I'll ask him. Sam typically doesn't do computer stuff but Will does. A phone call heads up is helpful. BTW Will moved to the Pacific Northwest so allow for that time change.

Adjust

Loman,
I have just finished fitting a James cowling to a RV-6....
You may be creating some of your problems by forcing the spinner area to be perfect with your plywood form. From what I see and read, I would release the spinner area and see what you get. This should make the inlets better and the spinner not perfect. The spinner area is somewhat easier to adjust and the layup in that area is pretty thick and allows for more sanding to fit, etc. The same goes for the inlet areas, you may have to grind some areas and build up others, use heat etc, but with some manipulation, it should come together. FYI...it doesn't come perfect from "James"...and the instructions are very sparse at best. I had to adjust everywhere around the nose for an acceptable fit. Keep at it.

Bob Martin said:

You may be creating some of your problems by forcing the spinner area to be perfect with your plywood form. From what I see and read, I would release the spinner area and see what you get. This should make the inlets better and the spinner not perfect. The spinner area is somewhat easier to adjust and the layup in that area is pretty thick and allows for more sanding to fit, etc.

Click to expand...

I agree. Another thing to keep in mind ... you could pull the top/bottom half side joints true and then check the spinner area alignment. Since you'll have either camloks or hinges on the horizontal joints, they'll be pulled up tight all the time. The question is, what does that do to the alignment between the air intakes and the spinner flange? That's where I had used micro on my SJ cowl to make up the top/bottom misaligment. All other areas, including air intakes, matched up nicely.
The SJ cowl was quite a bit of work, but I'm very pleased with the looks and the cooling performance. That latter, with plenum, is spectacular.

Sam James cowl

I worked on mine over the weekend , perfect fit . I drilled out a few rivets at the firewall and clecoed the cowl in place , as I marked out the final trimmings. any support other than a stand under the inlet snout changes the shape. I would not cleco or clamp it to the spinner backplate , remember the cowl is only attached to the fuselage at the firewall , all ajustments need to take place there.
Some 40 grit on a 4"x12" board is perfect for "sneaking up " on the final fit.
I can email some photos of the install .
Tom