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What is the best way to hold a cowl on?

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What is the best way to hold a cowl on?

Old 06-18-2015, 08:58 AM
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Default What is the best way to hold a cowl on?

I have numerous planes with cowls, that eventually wind up with holes in the cowl oblonging and with screws that won't hold. I have tried putting CA hinge material under the cowl and the rubber backed washers. Velcro works in some situations, but distorts the cowl some. All hold for a little while but they also loosen up and either fall out or strip out. If some of you have ideas on the a better way please chime in and maybe some with pictures on what works for you. The best way so far for me has been with cowl rings attached to engine bulkhead, can't do that with all planes though.
Old 06-18-2015, 09:14 AM
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I've glued the correct size washers on the outside of the cowl with black or flexible CA. Holds for most of a season but needs maintenance.
Old 06-18-2015, 09:56 AM
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There is an excellent article in the latest RC Sport Flyer mag on making it to fit most planes.....
Old 06-18-2015, 11:46 AM
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The best solution really depends on the cowl and its mounting method. For a cowl screwed on around the perimeter of the rear edge which I assume you're talking about, I use pieces of thin G10 epoxied inside the cowl and a piece of inner nyrod in the cowl mounting block. This assumes that you have the ability to offset or recess the cowl mounting blocks to account for the G10.

Last edited by RBACONS; 06-18-2015 at 03:45 PM.
Old 06-18-2015, 06:57 PM
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You can also screw from the front, just behind the spinner, which needs to be removed. Thread it right into the glass motor mount. Locating pins on the rear of the cowl into the firewall are needed. I don't use cowls as a rule, but it is another method.
Old 06-19-2015, 03:14 AM
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I like to mount a cowl ring on the back edge of the cowling and conceal all fasteners.

Bob
Old 06-19-2015, 04:33 AM
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Originally Posted by RBACONS
... I use pieces of thin G10 epoxied inside the cowl .....
Hi please explain what 'G10" is, thanks.
Old 06-19-2015, 05:40 AM
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Circuit board epoxy/fiberglass. http://www.thunderboltrc.com/index.p...&cPath=113_146 There is also a carbon fiber sheet too.
Old 06-19-2015, 07:17 AM
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Thanks all for the input, I like using cowl rings but unfortunately some models do not have access to them as the front opening has room only for prop shaft. Haven't tried gluing the rubber backed washers on and haven't tried the flexible CA. Thanks all.
Old 06-19-2015, 03:07 PM
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What kind of cowl is it? Structural (it actually holds something, like the motor), or cosmetic (all it does is cover something, like the motor)?
Old 06-19-2015, 06:30 PM
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there are a couple P51 with gas engines, one is a sig 300xs, my yaks and sbachs all have cowl rings which I really like. The sig had an open cowl but has been enclosed as the engine is inverted an cooling is down below and can't reach to the top any more. I am try the flexible CA and rubber washers- see how that works out. I want to thank all for the input and will let you know if I find a great way to fix this simple but annoying problem.
Old 06-20-2015, 02:39 PM
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I was going to try and use bullet connectors and a cowl ring.
Old 08-02-2015, 09:56 PM
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I gave up with screws & now use clear mylar tape run around the edge of the cowl
Old 09-01-2015, 09:00 AM
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One word Silicone!

Plane old 100% silicone from walmart etc. Make sure you have all your holes lined up the way you want it, add silicone behind the screw location and around certain areas of the primiter for even more support.

What this dose it prevents the whole cowl from comeing lose working around the screw locations that cause the damge at those spots.

Me and my boys use it all the time on our Bigg 100CC + planes. Its great, and when you have to take off the cowl, once you remove your screws just slowly pully off the cowl. You will have to remove most of the old silicon before reapling as silicon will not stick well to its self.

It dose take all night to dry and its very easy to clean up if it squishes out past the cowl before it drys.

Good Luck Mike
Old 09-01-2015, 02:40 PM
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Fiberglass washers to the inside surface of the cowling, then drill the hole out of the washer. Waaalaaaa... No more messy holes
Old 09-01-2015, 04:00 PM
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+1. I use a piece of thin G10 epoxied on the inside of the cowl where the mounting screws go. G10 is forever.
Old 09-01-2015, 05:32 PM
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Originally Posted by IRCantankerous
I have numerous planes with cowls, that eventually wind up with holes in the cowl oblonging and with screws that won't hold. I have tried putting CA hinge material under the cowl and the rubber backed washers. Velcro works in some situations, but distorts the cowl some. All hold for a little while but they also loosen up and either fall out or strip out. If some of you have ideas on the a better way please chime in and maybe some with pictures on what works for you. The best way so far for me has been with cowl rings attached to engine bulkhead, can't do that with all planes though.
Do it just as you describe . . . but, back out the screws and CA the holes to strengthen them. Then, before you put the screws back in (wait half an hour so the CA doesn't grab them) cut a 1/8" piece of glow fuel tubing and put it on the screw. This smushes out and makes a gasket that prevents vibration from opening the hole. I use the Futaba servo screws that have the flange around them and a shaft with out threads so it doesn't cut into the cowl. I make the firewall blocks out of maple or basswood.

The CA on hinge material is a good step as well.

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