German Aircraft Tire Experiment

[Gil]

Hello All,

Decided that an attempt at making tires for the main gear of a WWII German aircraft would be a good way to exercise a continuing exploration of the open petal natural closing forming technique. The photo shows the result of the third attempt at forming a 16 segment tire.
As usual the initial idea didn't work quite the way it was envisioned. Several other methods were tried prior to falling on one that "sort" of works leaving room for further improvement. I'm pretty happy with the progress on this so far and have learned some interesting insights of this technique...,

+Gil

[Leif Ohlsson]

I wonder what kind of shaping tool you came up with for this one, Gil! - L.

[pahorace]

Hello Gil,
expect this your tip, to best manage this, in the red box:

Orazio

[Gil]

Leif, Orazio,

It uses a slightly modified version of the wound roll-up form. I've run into problems where the tire curves back in toward the rim. It might be a simple forming technique sequence which is not quite right in the forming order. As usual a break is required to ponder the problem.

Yes, Orazio, that's exactly the type of situation this technique is intended to solve. In fact part F may be key to the solution. It maintains the outer diameter of the torus which I've come to realize as important to the forming process. Thanks!

The goal is a technique that's easier than slabbing together enough layers and grinding away anything that's not a tire. Making the forming operation self closing with an easy to make building aid is still the central idea. I still feel that it's doable but needs a little further development to see it through...,

Idea inputs always welcome!

+Gil

[shrike]

Perhaps an hourglass or spool shaped hub for the petals to attach to?

[B-Manic]

How about something like an expanding tire building drum. You would only need to use the interior portion. Of course it would be very challenging.

[milenio3]

I'm eager to follow your techniques, Gil. Thanks.

[Gil]

After several further attempts it became apparent that the petals always folded at the same place. The self forming method only works if there is an "arch". Alas, the place where they folded was the point where the "arch" no longer exists, hence the reason they always "fold" at the same point (Homer Simpson sound here).
I decided to use a piece of 0.5 mm cardboard soaked with nitrate dope (to keep it from coming apart when damp). The cutout piece was formed around a brass tube of about the same circular cross section as the modeled tire. The part was allowed to dry before forming it into a circular shape and taping with a thin strip of low tack masking tape. PVA cement was then spread on the surface and worked between the petals and the part hand formed using a dapping block, a roll-up form and a clear plastic cup with a flat bottom. PVA was then spread inside and the part allowed to dry before being sanded. A coat or two of nitrate dope was applied in between sandings to aid in sandability.
Although it's not self forming it does have one redeeming feature, it models the original very well but does seem to be a lot of work. This may be because this is the first time through with the lot of it. I'll see if I feel this way after number two. Thinking about mounting it on a mandrel to speed up the sanding chore...,

+Gil

P.S. If you look closely you can see the yellow color and black printing from the cereal box the cardboard came from...,

[Gil]

A German Aircraft tire in the form of a 1:33 scale model of a 935 x 345 aircraft tire is presented below. Still has a few blems that I'll blame on the learning curve. Should clear up on the next one (now that I might actually pretend to know what it is that I'm trying to do...,).
The other tire sitting in the roll-up form is the first tire pictured in this thread (sorry about that too glossy finish, gah!).
The yellow inside shows that it's a piece of a genuine cereal box card board (the 0.5 mm cereal box kind)..., Can't be authentic without it!

+Gil

[Leif Ohlsson]

Hey, that's more like it - now I'm beginning to understand the application of the roll-up mold, too! You've got to turn it over and "bake it" on both sides, right? - Leif