I purchased a Nitro models yak. it comes with a cowl ring but it is not attached to the cowl.
Any suggestions how to mount it to the cowl and what glue would be best?

Thanks for the help

Eric,

Is the cowl fiber glass ? If it is, get your hands on some HYSOL 9462. Its a bit pricey and a slow set time but will hold the ring for the life of the plane.
I dont think there is anything better for this application (wood to fiber).

Thank you.
yes it is fiberglass and where do i find this stuff?

Its a Loctite product so you may be able to find it locally. Automotive ,Marine and aircraft supply houses sometimes carry it. To order from the web,

http://troybuiltmodels.com/AdhesivesHysol.htm

While we are on the subject of cowl rings.

I am putting together a Sea Fury ARF and it includes a ply cowl ring. The instructions dont show how this is put on the model..

Do I glue the ring into the cowl then use screws to screw the cowl ring to the fuse?

If so whats the best way to make sure the cowl will sit straight etc?

I was thinking of inserting the wooden ring into the cowl and lining everything up. Then put a couple of drops of CA onto where the cowl ring sits on the cowl.

Once this is set use 30 minute epoxy to glue the ring onto the cowl fully??

If I am way off track let me know.

Dont want to stuff this up.


Or is the cowl ring there just so the cowl stays round when its screwed to the model?

Note: this is generic... the same technique I've used on many different arfs...

Temporarily install the engine into the plane w/o muffler or any other protrusions.

Put plastic over the firewall.

Place the cowl ring in place against the firewall.

Put four or six dabs of 30 minute epoxy on the edges of the cowl ring. DO NOT saturate it, you merely want the epoxy to hold it in place...

Slide the cowl into position.

Put on the thrust washer, spinner and prop.

Align the cowl to the spinner leaving enough clearance for spinners ( remember that some spinners are "deeper" so allow for this in case you upgrade later.. ).

Tape the cowl into the final position it should always sit once installed.

Look through the cooling holes and make sure the ring is in contact with the cowl and there is a bit of expoxy joining the two at, at least four points... if needed CAREFULLY drip or apply a bit more epoxy.

Let dry.

Remove the prop, spinner, cowl and engine.

Since you used only a little epoxy you can always break or cut it out in case of an error.

If everything is OK apply a bead of epoxy on the inside and outside of the cowl ring ( or rather in front and behind... ).

Let dry... done.


Ca dries too quickly to make minute adjustments, use the technique above...



It depends upon the plane...

Some planes actually have magnets in both the cowl ring and the firewall. These are also VERY easy to install yourself!

Recess the magnets into the firewall so they sit ALMOST flush with the firewall, leave them protruding about 1/32" from the firewall... round magnets work best...

Place INK on the magnets.

Slide the now dry cowl ring in place and press.

Drill ( I dremel ) holes for the opposite magnets into the ring where the ink made a mark.

Recess & glue the magnets in the ring again letting them protrude about 1/32" from the ring... get the POLARITIES RIGHT!!!

You'll never need to use screws, particularly if you use at least four pairs of magnets...

To remove the cowl, merely remove the prop, and pull it off!

Simple!

Okay, I'm the king of cowl rings.

I first tried it on my GP Patty Wagstaff Extra 300S ARF. I built about four of those each with a cowl ring. Next was the GP Christen Eagle ARF and we encorporated the cowl ring into the kit.

I've now built four GP 27% Extra 330S ARFs of my own, each using a cowl ring and finally my GP 27% Edge 540 ARF also using a cowl ring.

All have fiberglass cowls, but I'm not certain what resin they were "laid up" with (epoxy or polyester). I would bet they were made with polyester resin.

First, attach the cowl ring without the cowl to the fuselage. For my first Extra I used 6-32 socket-head cap screws, but now I use 4-40 and those are fine for up to (and over?) 50cc planes. Use blind nuts on the back of the former that you are bolting the cowl ring to. And you'll need an extended ball-end Allen wrench to get to the screws once the cowl is glued on. You can make an extended Allen wrench first by using a Dremel with a cutoff wheel to cut a regular Allen wrench in half. Then, using silver solder, splice a piece of 4-40 pushrod wire between the two halves using 1/8" (or is it the next size larger?) brass tubes to "sleeve" them together.

Also, once you have your cowl ring bolted to the fuselage, drill a 1/8" hole through the cowl ring and into the former on each side. Insert 1/8" wood dowels into the holes and glue the dowls to the ring, but not to the fuse. This will perfectly align the ring with the fuse when installing the cowl later on.

Mount your engine. This is when I "rough-cut" the hole in the cowl for the head of the engine (if it sticks out). Just cut the hole where you think it should be, starting extra small. Test fit the cowl and mark, then cut where necessary to get the cowl on.

Once you can get the cowl over the engine, roughen the inside of the cowl where the ring will go with coarse sandpaper. Fit the cowl over the fuse and ring, mount your spinner (and prop if necessary), then somehow "clamp" the cowl to the ring and fuse. You can use masking tape, but what I found works best is to hook five or six #64 rubber bands together and put them around the cowl over the cowl ring as though it is one large rubber band. Now you can adjust the position of the cowl and it will stay put without glue.

Okay, your cowl is lined up (be sure to look it for a wile from all angles), so time to glue. All you need to do is tack it in a few spots so it won't move when you take off the cowl so you can securely glue it later.

This can be the hardest part, so work carefully. What I do is drip medium CA down into the cowl in a few spots trying to get it to land on the ring and cowl where they touch. You don't want to use too much otherwise it may leak onto the fuse gluing the ring to the fuse. I usually have the model upside-down and can drip glue down through the opening in the bottom of the cowl for the air outlet. You can always follow up with accelerator so the CA doesn't wick past the ring onto the fuse.

Once the ring is tacked to the cowl, use your extended Allen wrench to un do the scews and remove the cowl. Now securely glue the ring to the cowl. I used to use epoxy, but I have found that CA adheres better - at least to the kind of fiberglass used on GP ARFs.

Now that the ring is permenantly glued to the cowl, you can perfect the cutout for the engine head and any other holes needed (for the muffler, needle valves, etc.).

Notes:
In some cases you will not be able to get to all the screws through the front of the cowl. Then, you will have to cut slots in the cowl to accommodate your wrench.

If you use the correct-size drill to drill the holes in the ring for the screws, they won't fall out when you take off the cowl. I forget the exact size, maybe I will post size later.

When it's all done, fuelproof with epoxy thinned with alcohol.

Here are a few verious pics from my recent Edge build and my Extra;