A little cowl help?

[Weefle]

Started on the stock cowl today. Top went very well. I’m using Skybolts for the firewall and hing for the horizontal split. Set up the bottom cowl and trimmed it to fit. I thought there was supposed to be excess material to remove for the split. Not so with my cowl. The right side is just barely going to make it but the left side I have a 1/2” gap at the aft end. Not sure what the best move fwd is. Install the hinge and lay some flow between hinge and cowl scarf a slice into the lower cowl and then cut the line? The front corners all fit quite well.

Any advice appreciated .

Keith

 

[PaulvS]

The gap at the side can be fixed by extending the sides using a scarf joint and layup of an epoxy glass extension. This should definitely be done before fitting the hinges and with the lower cowl on the bench. But first, is the bottom of the cowl tight up against the lower firewall? While fitting my cowl (-6A) I used duct tape to pull everything together and hold it in place while checking and marking.

Also, is the disk that simulates the prop flange in the right position? It looks like you are using EZ-cowl tool, whereas I used the extension for the fixed prop, so maybe that is why it looks a little bit different.

There were gaps at the front on my cowl also, it takes a lot of filling and sanding to get the parts into a decent state.

 

[Kyle Boatright]

If you look at the second picture, the bottom of the cowl isn’t flush with the fuselage. It s sitting low. Not sure fixing that’ll give you enough to close the whole gap, but it will help.

 

[BravoAlphaRomeo]

It looks like in the picture that the line (or cut) on your upper cowl is wavy. That should be a straight line. Can be fixed with a long sanding block. After that is perfectly straight on both sides and the lower cowl is added on to when you transfer the “cut” line onto the lower cowl, it will be straight. Good luck

 

[mturnerb]

It looks like in the picture that the line (or cut) on your upper cowl is wavy. That should be a straight line. Can be fixed with a long sanding block. After that is perfectly straight on both sides and the lower cowl is added on to when you transfer the “cut” line onto the lower cowl, it will be straight. Good luck

I like the dimensioned hardwood (poplar) at the aviation department of Home Depot - usually a good flat/straight edge, and this sandpaper is great to use on the block: https://www.amazon.com/gp/product/B0000223SI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

 

[Weefle]

If you look at the second picture, the bottom of the cowl isn’t flush with the fuselage. It s sitting low. Not sure fixing that’ll give you enough to close the whole gap, but it will help.

Good observation. At both corners the cowl sits about .030 proud. But on the bottom it’s flush. It’s like the cowl radius is slightly off from the fuselage. Even at that there is not enough play to bring up the gap. I’ve sent a note to mothership but I’m sure im on my own to scarf the joint and build on. More dust in shop!

k

 

[Lerd]

Started on the stock cowl today. Top went very well. I’m using Skybolts for the firewall and hing for the horizontal split. Set up the bottom cowl and trimmed it to fit. I thought there was supposed to be excess material to remove for the split. Not so with my cowl. The right side is just barely going to make it but the left side I have a 1/2” gap at the aft end. Not sure what the best move fwd is. Install the hinge and lay some flow between hinge and cowl scarf a slice into the lower cowl and then cut the line? The front corners all fit quite well.

Any advice appreciated .View attachment 56500View attachment 56501View attachment 56502

Keith




View attachment 56499

my-10 cowl is the same as yours. Right side is a good horizontal fit with no trimming. Left side I have a 3/16 gap at the aft end. I sent an email to the mothership last week but I have not recieved a reply. There was no overlap in either side to trim off.

 

[wirejock]

my-10 cowl is the same as yours. Right side is a good horizontal fit with no trimming. Left side I have a 3/16 gap at the aft end. I sent an email to the mothership last week but I have not recieved a reply. There was no overlap in either side to trim off.

For what it's worth...7A
A couple things to check.
Make sure the cowls are snug. Probably done.
I wanted the cowl split to mirror the longerons so I used a straight edge to extend a line from the front split aft to the fuse aligned to the same level and made a mark on the fuse. Ultimately mine needed a scarf added to one side of the bottom cowl.
From there it waa easy to add a scarf before final trim.

 

[Dr_Dave_MT]

I like the dimensioned hardwood (poplar) at the aviation department of Home Depot - usually a good flat/straight edge, and this sandpaper is great to use on the block: https://www.amazon.com/gp/product/B0000223SI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

"Dimensional Hardwood and Home Depot" is an oxymoron, like Military Intelligence...

 

[raabs]

I scarfed the joints on both sides with carbon fiber sandwiched in fiberglass (same for aft edges all the way around) to prevent pillowing under pressure. Sandwich CF to prevent corrosion of skybolts (same for hinge) and added a LOT of rigidity. Then cut/sanded with long permagrit blocks. Worked well. Permagrit blocks worth every penny x1000 for the cowl. https://permagrit.com/collections/sanding-blocks

 

[Weefle]

my-10 cowl is the same as yours. Right side is a good horizontal fit with no trimming. Left side I have a 3/16 gap at the aft end. I sent an email to the mothership last week but I have not recieved a reply. There was no overlap in either side to trim off.

The reply I got from Vans was that I needed to have the prop installed to fit the cowl. Ok, but that’s why we use a spacer so we’re not fiddling with the prop in the way taking that cowl on and off. It was spaced correctly . I had to scarf the joint as others said to make up the gap. I think they are trimming too much off at the place that makes the cowls. Once you add the extra glass then you can straighten that horizontal line and proceed to doing the hinge or skybolt.

hope this helps.

keith

 

[FlightTwins]

We had to add 9/16 to the right side.

 

[mturnerb]

"Dimensional Hardwood and Home Depot" is an oxymoron, like Military Intelligence...

I realize your intent to be humorous but the pieces of poplar I got at HD were stable and flat, over a long period of time - I'm still using them after several years. I used a Starrett straightedge to check flatness: of course the wood is never as perfect as a reference metal edge but it was good enough for the purpose. 2 by 4's a different matter of course but I've dug through their piles a number of times - the kiln dried stuff - and came away with enough decent lumber to meet my meager needs.

 

[seattleworm]

I also had a gap between the top and lower cowling halves, though the gap is small, about 1/8"-3/16". I just sanded both halves straight, and filled the gap with flox mix without additional glass layer. For bigger gap, additional layer of glass might be needed.