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PostPosted: Thu Nov 02, 2006 9:58 am
by JPXman
Been thinking about this problem:

like Karl says, the key is to start with one side of the skin temporarily fastened to (i would say) the BOTTOM of the spar.

then, with the help of straps, buddies, whatever - bend the skin up so its pointing up vertically (with the skin nice and tight against the noseribs on the bottom), and then with a marker, make marks where the front of the noseribs are touching the skin on the inside.

take the skin off, make a line connecting the dots, and then use a long steel pipe of about 1" radius (guess?) to make the new tight bend leading edge round over this pipe along the marker line.

then you should be able to fold over the skin to the top of the sparcap and make your new holes in the skin to make it tight. tighten the whole thing with straps before you make the finished holes.


PostPosted: Thu Nov 02, 2006 10:17 am
by russell
The real obstacle here, for me, is the fact that one end has a bend radius of 1/2" and the other has a radius of about 4" at he nose. I can't wrap my brain around that just yet. You guys keep talking.


PostPosted: Thu Nov 02, 2006 11:24 am
by Shannon
I'm thinking that tapered wood shaped like a Pool Que or table leg could be tested. Maybe a complex jig is the only way to get this done properly. I don't know ?

There is also the issue of material. Can the metal be purchased in the needed width. A 4x8 sheet of aluminum is fine for doubler material on the main (large) portion of the D-cell. Fabricating the end portion of the D-cell skin may be a different story as you may need wider material. You see the aluminum has a grain in it and ideally you want to bend and shape the metal "with" the grain. On a 4x8 sheet of aluminum the grain runs across the 4' width rather than the 8' length.

This would be a super time for anyone familiar with the original fabrication process to step forward with some ideas, hints, pics maybe ???? Something ? Anything ? Hello, anybody out THERE...There...there ?

PostPosted: Thu Nov 02, 2006 12:29 pm
by russell
Man, you're right about that! I keep hoping that smart fellow named Dale Kramer might still be following this site and toss me a life vest!

PostPosted: Thu Nov 02, 2006 1:29 pm
by flyalaz
Good one SHANNON...Shannon...shannon!

If a couple more intermediate ribs were made from wood, would it not be possible to form the skin around them? The material is thin enough that even though it isn't bent around a form, it should take and keep the form where it is bent around a rib.

If that doesn't work, then a full leading edge form for that tip section could be made by first stacking foam blocks and cutting the entire profile from inboard rib to outboard tip, separate, trace onto wood blocks, cut and glue / nail those together, and then you have your form. Heck of a production, but after filling and sanding (the bottom surface ribs would have a bevel I think) you will have the proper shape.


PostPosted: Thu Nov 02, 2006 5:08 pm
by Shannon
I'd imagine Ultraflight used some type of "press-form" jig where an "outer" mock-up of the D-cell (or nose of the D-cell) pressed flat sheet into another corresponding "inner" D-cell shaped form. Think of it as flat sheet being pressed into continuous row of wooden wing saddles.

Could such jigs could be made entirely from wood using the foam ribs as a pattern ? They would be a good bit of work to construct as they would need to be smooth and uniform. Systems for hoisting and alignment surely would be needed to ensure a uniform press. Pondering the hypothetical process maybe if the metal being formed was intentionally left long it would be an easy matter to mark and trim off excess after a preliminary fit over the ribs and spar.

Lots to think about.... lots of questions.... very few answers. I'm sure it could be done by anyone intrepid enough to try it. If going through the trouble of figuring it out meant the difference between having a Lazair or not you can bet I'd "Get er' done".

PostPosted: Thu Nov 02, 2006 11:53 pm
by Shannon
russellrewis @ Nov 2 2006, 07:54 AM wrote: Shannon, not that it's any help to Lazair 4 Ever's plight, but just for discussions sake I thouhgt I'd just jump in and say that none of the foam ribs in the wings of my Lazair have glue on them any where except on the spar.

Russell I think there was a bit of an evolution on how Ultraflight applied glue to the foam ribs. Initially I think the chain of thought was to simply glue the back of the ribs to the spar channel. At some point the paradigm shifted with glue applied around the entire perimeter and/or continuous beads run along the nose of the skin.

How best to apply new adhesive would be open to personal interpretation. My idea is to apply enough in the right places to feel good about the whole situation for another 20+ years.

PostPosted: Fri Nov 03, 2006 8:15 am
by russell
Shannon, glad to learn that the later kits had the ribs glued all 'round because I really wanted to do this but was hesitant for I thought there possibly was a reason not to. I respect Dale Kramer's knowledge of design and fear my lack of same so I figured he probably knew better than to do it.
As for trying to devise a method to form the skin, I become relentless in trying to solve a problem and even though I may succeed, I might have no use at all for what I've accomplished! Just self gratification I quess. Kinda like that song you can't get out of your head and you go around all day catching yourself humming it.

PostPosted: Fri Nov 03, 2006 10:38 am
by JPXman
I would recommend scuffing the inside of the skin where the glue will be applied too - that aluminum is pretty smooth and only the best glue might grab it. scuff it up and anything will stick to it.

as for the increasing-radius-bend, you could accomplish this with a 1/2" pipe, just don't bend the outboard part as much? its not rocket science - bend a little and fit and check, take it off, bend it a little and fit and check etc... who has ever done something to their lazair properly on the very first attempt?????


PS: oh yah, no need to make a new outboard skin with that little sharp end on it for the wingtip bow - buy mike mckusicks fibreglass tips and bolt them on. that sharp bit is not required and actually gets in the way

PostPosted: Fri Nov 03, 2006 12:14 pm
by bdiedenhofen
Is Mike Mckusick still in business? I want to get some fibreglass wing tips, but the email address and phone number listed don't work. Has anyone spoken to him recently?
Brian D.