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Old 03-08-2018, 10:04 PM
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majuro15 majuro15 is offline
Join Date: Feb 2013
Location: Charlotte, NC
Posts: 387
Default Splitting a Show Planes Lower Cowl

As Iím seeing more and more flying examples of the Show Planes cowl, Iím wondering if it would be possible to modify the lower cowl to make it two pieces. This would immensely aid in removing it and not having to take the spinner or nose pant off.

My thought is to simply cut down the center line (body buttocks line as USAF calls it) and lay up a sturdy fiberglass or aluminum flange for Skybolts or a piano hinge. The top comes off as normal and then each side of the lower cowl simply comes off to each side.

Itíd also eliminate the nose wheel slot requirement. The rear of the lower cowl near the exhaust would still mount to the bracket per the plans.

Am I crazy?
Tim Huneycutt, Capt, NCANG
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Old 03-08-2018, 10:37 PM
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Mike S Mike S is online now
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Location: Dayton Airpark, NV A34
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Originally Posted by majuro15 View Post
My thought is to simply cut down the center line (body buttocks line as USAF calls it) and lay up a sturdy fiberglass or aluminum flange for Skybolts or a piano hinge.

Am I crazy?
No, not crazy at all.

I have no actual knowledge of the way the cowl is made, but I can tell you how to do the work you are proposing. Most likely there are many ways to do this, but I have had success on other fiberglass parts with this method.

First lay out the line where you want to do the split. Then, cut 3 or 4 inch long sections along the line, leaving about a 1/4" uncut to hold the two parts in correct alignment.

Once you have the cuts from end to end, clean and scuff one side of the cut line on the inside of the cowl. On the other side, lay packing tape or duct tape or whatever release material you choose. lay it wide enough to have plenty of of safety margin so there is no chance of the wet layup you will be doing goes wide of the release tape.

Now, do a layup across the slit line, centered over the slit. I would guess 4 inches wide would be fine. Use bid, 3 or 4 layers depending on the weight of fabric. If in doubt, more is better than less----------you do not want this to come apart in flight

After your layup is fully cured, drill holes for your fasteners from the outside, on the side with the release tape. These can be just pilot holes at this time.

Now, cut through the tabs you left in the split line and make the split continuous. Now you should be able to pop the two halves apart, and you will have a correctly contoured flange with matched holes for fasteners to hold it back together.

The cowl is most likely made with honeycomb center, if so, you should dig out a bit of this along the split line, and fill with flox to strengthen the cut edges.

Also, if there is honeycomb, it would be a good idea to back drill from the inner skin----do not drill through the outer skin!!--- to open up the area around the fasteners, and add flox to the areas of the drilled holes so the fasteners dont crush the honeycomb. After the flox cures, re-drill the fastener holes from the exterior.
Mike Starkey
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Flying as of 12/4/2010

Phase 1 done, 2/4/2011

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Last edited by Mike S : 03-08-2018 at 11:18 PM.
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Old 03-09-2018, 03:01 AM
Skymanw Skymanw is offline
Join Date: Jan 2015
Location: Nolensville, TN
Posts: 30

I have the Show Planes cowl and really like it. Love the looks of it!

I had considered splitting the lower cowl as well and wish I had. I enlisted help finishing the project and we just didn't take the time to do it but I certainly think it would be worth while. I don't necessarily have trouble taking the bottom cowl off but it really goes a lot better with two people. Splitting it, I think, would make it so much easier for one person to remove.

Sounds like Mike S. laid out a good process for it. Best of luck with it.
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Old 03-09-2018, 04:14 AM
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Jesse Jesse is offline
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We have done this a number of times with the standard cowl and it works great. It makes changing the oil much easier as well as any work in the lower cowl area. We used the process Mike S describes, more or less.
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Old 03-09-2018, 08:23 AM
rocketman1988 rocketman1988 is offline
Join Date: Jun 2010
Location: Sunman, IN
Posts: 800
Default cowl

I have the showplanes cowl.

I am not sure why you would want to split it. There is a f/g fairing that goes around and forward of the nose gear assembly. The lower cowl is secured to this fairing using 8 camlocs. This allows you to create a long slot in the lower cowling, much like the ones detailed in this forum for the stock cowl. The difference is that when you install the showplanes lower cowl, that slot is automatically covered and secured by the fixed inner fairing.

The point is, when removing the cowl, I can drop it nearly straight down from the spinner, over the nose gear leg, and then forward between the prop blades. The prop/spinner does not need to be removed to remove the cowl.

I have been able to install and remove my cowl many times by myself with no issues...of course, it isn't painted yet. When painted, I think I would want another pair of hands to help just to preserve the paint job.

Splitting the cowl was something that I toyed with while doing the install. It is a honeycomb structure that you would be splitting. If you were going to do the split, you would probably need to do it AFTER you fit the entire cowl, if you are using the showplanes induction system. The intake plenums are, well, a bit of a challenge to get lined up properly with the cowl. Splitting it before you get the plenums would add another variable to the mix.

All that being said, I really like the cowl and induction system now that it is installed. I used the Skybolt kit, and their preformed brackets work really well. It looks great and cowl removal/installation takes about two minutes.
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Old 03-09-2018, 05:07 PM
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majuro15 majuro15 is offline
Join Date: Feb 2013
Location: Charlotte, NC
Posts: 387

Good feedback, thanks.

I'd definitely fit the cowl and intake before splitting it. Splitting it would be the last thing, honestly. I just know of a lot of folks who have issues with installing it. I'd like it to be a one person job.

But again, as always, to each their own and this is the great thing about experimental aviation!
Tim Huneycutt, Capt, NCANG
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Old 03-09-2018, 06:36 PM
rockwoodrv9 rockwoodrv9 is online now
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Location: Meridian ID, Aspen CO
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I may try it on the James cowl I have on my 9A next winter. I can barely get it on and off now with no gear fairings or pants on with my 3 blade Catto. Im not sure I could with them on.

The only issue on the 9 and James cowl is the air intake. Splitting or going to one side would take some work. I have seen pictures of it done so it has to be possible!
Meridian Idaho
O-320 D2A
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Old 03-10-2018, 05:48 AM
Chris Engler Chris Engler is offline
Join Date: Aug 2012
Location: Greene, NY
Posts: 53

I've got a Showplanes cowl on an 8 and have installed and have removed many times by myself with the prop/spinner on. I've got Skybolt fasteners around the firewall perimeter and hinge pins along the top/bottom horizontal seam. I'm planning to leave the Skybolt retainers off after paint and remove the fasteners completely whenever I remove the cowl to avoid scratches.
Chris Engler, Greene, NY

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Old 03-10-2018, 06:05 AM
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snopercod snopercod is offline
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Location: Asheville, NC
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Default Cod Piece

I have no idea what a "Show Planes Cowl" looks like but, on my Lancair, I made the bottom of the lower cowl removable so I could change the oil, check the carburetor linkages, and gain access to the air filter without removing the top and bottom cowling halves. This is the bottom cowling half with the "cod piece" removed:

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