stunthanger.com
Building Tips and technical articles. => Building techniques => Topic started by: John KruziK on November 22, 2009, 01:19:12 PM
-
What is a good clean way to mount cowl? I was thinking of using some strong magnets. Trying to hide mounting screws always seems overly . Thanks John
-
Alot depends on what plane your building.
-
I realize their would be differences from plane to plane, but I am looking for generic way that might work for most planes. Say anything from a Perky to an Oriental Thanks John
-
Where would one get those strong magnets to hold on a cowl?
-
I've used 1/4"-diameter rare earth magnets. Sometimes they work; sometimes the cowl blows off. They only work if they are very close to the target: another magnet or, in my case, a bolt head. A local guy uses them with his electric plane, but had to supplement them with tape because they made an audible rattle. Now he uses bigger ones and is careful not to have positive air pressure inside the cowl. The T-Rex ARF uses big magnets:aybe 1/2" diameter. I haven't heard of them not working.
http://www.kjmagnetics.com/categories.asp?gclid=CLCc-cTSn54CFSn6agodZzxglQ
-
Big question here is would they work with 'audiment recovery system' (the electronic replacement push rod system that has received so much gadabout)?
Seriously, thanks for the site for the Rare Earth magnets. Gonna use them on the new Gee Bee and Mystery Ship cowls.
Look at the offerings, guys. There are drilled cube-shaped magnets, both along the line of magnetism and perpendicular.
An added dimension in our otherwise everyday mundane building...(joke)
-
I tired the rare earth magnets once. That was enough. Like Howard's experience, sometimes they worked fine, other times the cowl blew off. I've built several cowl that the screws were not evident. With the current PA plane, the cowl has a fixture that allows it to be held on with one screw from the front, behind the spinner. No exposed screws. The drawback is, you have to take off the spinner to get to the cowl screw. Not a big deal, but it is an inconvenience. I also had one that snapped into place. That worked really well, but was a bit@h to get aligned and set up properly and I was always afraid that as it wore in, it would get loose. Never did, but it was something to worry about.
As noted, a lot is dictated by the design. On the PA plane I'm painting right now, the cowl keys into the spinner ring and has two bolt that hold the rear on. The come up from the bottom and can't be seen when the plane is sitting on the gear. Should work out really well. It's all a matter of your creativity and what you want.
-
On my Nobler I duct the air from the engine cylinder right behind the engine, in the center bottom of the cowl. Way down inside that flat black duct there's a flat black hex socket screw that holds the cowl on.
It looks really slick. If the rains ever stop I'll tell you how it works.
Note that the cowl is keyed in place with plywood tabs so that when on it is only free to move straight down off the plane. So the screw only has one thing to do -- hold the cowl up to it's mounting.