DelRay

One method I have used to hold the extentions on a totally in cowl application where I didn't want to notch the cowl for cowl removal was the use of a spring. A throttle return spring found at any autostore or hardware store has the long straight ends on them and are perfect for this application. I cut a piece of aluminum tubing with an i.d. to fit over the end of the muffler pipe, and is long enough to go outside of the cowl area. I attach the one end of the spring to the upper end of the muffler by drilling and tapping the muffler or a smal clamp around the header pipe.There are many possibilities for securing that end of the spring. Laying the sping along side of the muffler I cut the other end of the spring long enough to be reached through the cowl pipe opening with a pair of needle nose pliers. This end of the spring I bend a hook in it. Install the pipe extention, pull the spring down and hook it on the end of the extention. I use this method even if the cowls are notched for removal. That aluminum tubing polishes up real nice also.

Deadeye

Could you supply a picture of this? The idea sounds great, but a picture is worth a thousand words.

opjose

Yes please I'm not visuallizing what you are saying.

DelRay

Ok, here's a few pics, like you said, a pic is worth a lot of words. I left the cowl on the 1/4 scale Cub and tried to get close enough to show the spring hook in the end of the extention pipe. The other pics with the cowl removed are of the 1/5 scale Cessna 182. The extention on the 182 exits so close to the edge of the cowl I went ahead and notched the edge of the cowl. I make longer header pipes with steel brake or fuel line and silver solder the stock fittings onto my new pipes. While I had the ends off I put the top spring attachment point over the pipe, just a small piece of aluminum with two holes in it, one hole about the size of the pipe the other for the spring to hook into. Cheap and dirty, but it works. Both of these applications are on four strokes, although the same technique could be used on a two stroke as well, just different methods of attachment for the top of the spring. A small width metal strap to go all the way around the muffler and held together with a small through-bolt could be used for the top end of the spring. I built a support bracket to help cut down the vibration on the 182 muffler, just some scrap aluminum .

mintie

A good idea....this is a common practise on some homebuilds,micolights and other full size. works fine. Sometimes the full size do have problems with the heat on the springs and they lose their tension. Models will be fine.....cheers