Rafael's introduction

[Botijo]

Hi:
Im restoring a 1938 Aeronca Chief airplane. The cowlings are a mess and need repairs and to manufacture 4 new pieces. My experience in metal forming is almost zero but it sounds like lots of fun so I would liek to get as much knowledge as possible

[HEATNBEAT]

Hi Rafael and welcome!

[Peter Tommasini]

HI Rafael welcome to the forum
Peter

[invision]

Welcome to AllMetalShaping Rafael. When you get a moment share some photos of your project, we love pictures.

[Botijo]

Thank you for the welcome. Here is a link with pics of the work so far. I need to post pics of the cowlings Im trying to rep[roduce. So far I have used a laser to trace lines on the arts and using a profile gauge I got cross sectiosn every 1/4 and made a flexible patter from them. Beyond that Im going to need you guys help in where to go from there
https://picasaweb.google.com/Fearles...iators/NC21366#

[Oraclejacket]

There is a market for someone to make nosebowls and bottom cowlings for these Pre-war Chiefs. I have two of them (airplane pojects), which I've posted about before, and I know of several other flyers and projects which could use new cowlings, since the originals are worn out and no new ones have been made in 70 years.

Is there anyone out there who would like to lose a few dollars making parts for old airplanes. ;-)

Rafael, what are the other two cowl parts you need (other than the nose bowl and bottom cowl)? The top cowl shouldn't be *that* bad to fabricate.

[Botijo]

My nosebowl is repairable, the bottom cowl is a mess with 15 patches and even patches over patches. Here is a link to the parts I need to make. I friend let me borrow these ones which are orignal and undamge.
https://picasaweb.google.com/1037476...eat=directlink#
I have no idea about metal working so Im trying to absorb all I can. So far I have used a profile gauge and have made templates fevey 1/4 of and inch with the idea of making a buck of the pice, dont kno what to do with it afterwards tho. I have also made the plexible templates of the entire pice but dont know what to do with it either.
I figure I try in these 4 pieces and then move to the bottom cowling. I was told of making a concrete mold male and female and just let the ewight do the forming but I dont know how to do that either.
Any ideas?

[Kerry Pinkerton]

Rafel, A couple things. First, you should read here a lot about basic shaping techniques. Second, you should buy David Gardiners "Shaping metal with hand tools" DVD. It will be the best $60 you spend on your restoration.

Now, regarding the flexible shape patterns or FSP, they are very powerful tools. They will tell you EXACTLY what has to be done to your panels. If they are loose in the center, you stretch, if they are tight on the edges, you shrink. You can shrink with a stump or tucking forks and hand tools. Again, do some reading. They will also tell you very quickly that there is NOT as much shape in the nose bowls as you think they are.

When you remove the FSP and lay it down on something flat, you'll see that while there is some shrinking required on the front portions, most of what you think is shape is actually just arrangement, that is, how the panel is bent and twisted. That is what the hard buck you made will tell you...how to twist and bend the panels to go into the proper arrangement.

If I recall correctly these are made from .050 3003 H14. Because they are so thin, I'd probably make them with shrinking techniques more than stretching techniques. If they were originally welded, it would have been with gas rather than TIG and you should be able to see the seams from the inside of your borrowed bowls. I could be wrong but it seems like I was told that the FAA will not allow TIG welding. Perhaps that only applies to structural components...

Originally Posted by Oraclejacket

...Is there anyone out there who would like to lose a few dollars making parts for old airplanes. ;-)...

Kyle, that is the heart of the matter. I'm not an airplane guy but we did take our machines down and set up in the vendor area of SunNFun for four years (last year was '07 I think...)...so I know what kind of parts you're talking about.

What I discovered is that a lot of folks came up talking about damaged cowls and wheel pants on their old planes. I actually cleaned up a set or two during each fly in just as a way of proving what could be done and because we were bored. However, MOST of the airplane guys were not interested in paying what it would actually cost to build or repair.

If you're serious about wanting some made, send me a PM.