Re: Any interest in a Group buy of Polyimide tubing?

From: <leop_at_lyradev.com>
Date: 11 Jan 2014 06:29:35 -0800

Everyone,
 

 There are more successful F1D fliers to copy but here is the polyimide tubing sizes I use for my F1D. My vp hubs use 0.072" ID tubing to hold the spars. I use both thin wall (0.00125") and thick wall (0.00375") for the hubs depending on the particular hub details and the desired final weight of the hub/prop combination. The thick wall tubing weighs about 9mg more than the thin wall in my F1D vp hubs. My prop spar sizes, 0.072", (as well has the vp tube ID) are the same that Ivan Treger specifies in his 2010 an 2012 F!D plans. I do not jam a square spar into the tube but rather have rounded ends on double tapered spars. This is important as the spar/tube combination provides the hinge support for the vp hub. The prop spars are locked to the tubes using a drop of Ambroid cement although the fit is very snug. There is at least one world class flier who has used Treger type vp hubs with 1/16" diameter spars. Spar size design decisions take more into account than just diameter (wood type, density, boron, etc.). BTW, my F1M and PP vp hubs use the thick wall 0.072" ID tube and corresponding size prop spar successfully. This does not mean that my F1D parts are too big and strong but rather reflect the balsa densities used (6# or less for F1D and 8# or more for the F1M/PP) for the prop spars.
 

 I use 0.064" ID thick wall (0.00375") polyimide tubes for all of my wing/stab spar to post connections. This is a design decision as I have found that the thin wall tube does not work for my designs and planes. Others have made the choice to use thin wall tubing in these circumstances and their planes have been quite successful. Again, such decisions are made by each individual. I also use round wing and stab posts. Others successfully use rectangular posts inserted into the (initially) round tubing. Again, these are individual design and build decisions and work well for the fliers that use the various different methods. BTW, I use the same size wing post tubing for my F1L and LPP planes.
 

 Finally, before Small Parts was bought out by Amazon, they had a very good selection of polyimide tubing sizes. However, I purchased most of my current supply of polyimide tubing from Furukawa, a Japanese manufacturer, as Small Parts had not yet started to carry a good selection of polyimide tubing when I first started using the tubing (for use other than in indoor planes). Mike Kirda has found an excellent US source for polyimide tubing in just about any size imaginable (Kudos to Mike) and at a reasonable price. The tubing is, I believe, actually made in the US. The only problem is that the minimum quantity for a purchase of any particular size is large (often 50' or more). Thus, Mike is trying to put together a group purchase. Again, many kudos to Mike.
 

 LeoP
Received on Sat Jan 11 2014 - 06:29:36 CET