I have goldberg edge 540 and I'm trying to find a scheme to mount the cowl so vibration is reduced. I have always had problems trying to keep the holes in the cowl from enlarging from vibration in my other glow airplanes. I want to do this one right ANY IDEAS?

After you have mounted the cowl, enlarge the holes to 1/4"

Insert a short piece of fuel tubing in each hole and secure with a screw and washer.

I like to use 5/32 nylon screws into hardwood blocks behind the cowl. At least 4 seems to contain the 4-stroker vibrations so far.

Go to the hardware store and get some sealing washers, they come in several sizes.

They have a rubber gasket sealed to one side and work PERFECTLY for this.

This is a picture of them http://www.apmselfsealingfasteners.c...ng_washers.asp

The best way is like MinnFlyer pictured! I have mounted nacels and cowels that way for years and not had one shatter out from vibration. Just make the hole large enough to "Squeeze" the fuel tubing in and that way it holds your screws in when you remove the cowl. Also check for prop balance. That can cause MAJOR shakes that you dont want!!

Thanks for the responses. It is appreciated!

Just a thought. Could you enlarge the holes in your cowl enough to insert short sections of small size silicone fuel tubing, insert a screw through the tubing and hope the fuel tubing mushroomed out enough to secure the cowl? You could test it on a scrap of something. An electrical supply store may have various size rubber gromets to feed wire through a sheet metal electrical chassis also.

Bill

Hey Mr. Smarty pants, keep shareing your "priciples" please.

Bill

The washer on top of the cowl under the screw is important

You can get nylon washers at the hardware store for this that are easier on your cowl

Does anybody have any pictures of their setups?

Perfect. You could even epoxy or CA them to the inside of the cowl and the mounting screw wouldn't even have to touch the cowl.

Bill

I've got to tell you. I have learned so much from guys like you during the past few months of being a member here. It's real nice. Decades of experience in just a few months. I'm going to take a long look at the cowl mounting on my new Brodak Oriental.

Thanks,
Bill

I use round servo grommets. Drill out the hole with a 5/32 bit, squeeze the grommet in. It stays in place in the center of the cowl, and also stands off the cowl from the covering or paint to reduce abrasion. A small washer can be used under the screw to compress the grommet. Here is an example. Most of us will have these grommets laying around.

PS. I wish I could do diagrams like Minnflyer.

Very nice. I KNEW there was a grommet out there somewhere.

Bill

I have used RTV / Silicon Sealant for years with great results. You actually "glue" the cowl to the fuselage. The trick is where to apply and how much. If you have wood blocks that stand off the firewall you apply a liberal amount to the blocks insuring it gets into the predrilled holes. When you secure it with screws/washers the RTV acts as a mild thread lock and will also form a silicon sleeve as depicted in post #2. Removing the cowl is accomplished by inserting a thin blade E-Prop or similar between the fuse and cowl to break the RTV bond. If you have a setup where the cowl slides over a Fiberglass fuselage "lip" you apply the RTV to the flat sides of the cowl only. - Stay away from the corners of the cowl with the RTV as they will not allow the insertion of the removal tool. Apply the RTV in 1" widths only where your pre drilled bolt holes are located. I have several Giant scale warbirds which contain a pound or more of leadshot/epoxy mix glued to the front inside of the cowl for balance and this method has worked perfect.

I use the method that Minn described as above and it's worked well for me. Just remember to not crank down on the wood screws too much. Just as the tubing makes contact with the cowling,,,maybe an 1/8 of a turn more in and that should do it. Don't want to compress it too much.

Good luck.

I just went to the Dubro website and they have a new cowl mount on the first page that you might be interested in.

Bill

http://www.shopatron.com/product/part_number=998/101.0
This is a direct link to the Dubro Cowl Fastener System
This is invaluable for the screws and washers even if you don't need the "L" brackets

Least obvious is simply to back the cowl with plywood sheet. Thin works fine. It doesn't crack or wallow out. And you only have the screw head and small washer outside the cowl, so it's a lot less noticable.

Hey w8, let's cut to the chase. What's your home phone number? (joke0

Bill

Since I adhere to the idea that "simple is good", and I'm cheap, my solution for many years is to use CA hinge material as a backing. After the initial hole has been made, I use about 1/2 of a CA hinge to cover the hole and CA it in place. Let it completely set, then redrill the cowl hole through the CA hinge. This stuff id remarkably tough and resilient. It gives good results on fiberglass or plastic cowls.

Those of you using ABS (plastic) cowls

Be forewarned that Epoxy doesn't stick to ABS for very long even if you rough up the plastic. About the first time you run the engine, it comes loose.

The solution is a can of ABS pipe cement from the discount store. Use the swab in the can to attach your fiberglass or CA hinge material. It will not get really hard for a few days. But it never comes loose.

You can then use epoxy on whatever you attached to the plastic.

I don't use epoxy on any type of plastic. I have had your experience. Elmer's makes their own sort of Gorilla glue which appears to adhere to anything but it's not very flexible. Thanks for your tip.

Bill

Servo grommets work in every material, and on any cowl. Cheap, available, easy to install without the need for glues, will not slip or allow the cowl to slide underneath as fuel tubing can (I used to use this method), reduces the contact of the rough back of a fiberglass cowl to the covering or paint around the fuselage, stays on the cowl when removed and reinstalled, can be painted to match the airframe, indeed, what is not to love.

Man, you should be in sales. You got my head bobbin'. Seriously, thanks, you make sense.

Bill