Shrinking inner sleeve

[astjp2]

Re: Shrinking inner sleeve

It depends on the diameter and wall thickness of the tubing, I have used a 1/2 conduit bender for 5/8" .058 wall tubing for making brake pedals. I would recommend an additional 2' of tubing for larger stuff and if you need to, you can use a straight 1/2" drive long extension on the inside of the tube on some sizes. Tim

[Marv]

Re: Shrinking inner sleeve

Mike draw it out with chalk on the floor and measure it and add what you want for leverage. Marv

[Hank Jarrett]

Re: Shrinking inner sleeve

The difference between "structural" and "non-structural" depends on who you talk to. For an engineer, EVERYTHING is structural, BUT.....All the strength that is needed is enough to carry the load with sufficient safety margin for ALL the loads the part will ever see. If Peanut Butter is strong enough for the loads, Peanut Butter is good to use. If you can convince the Feds that paper is strong enough for an airplanes primary structure, you can use it (Molt Taylor did with great success). Getting the Weindecker Eagle certified (the first certified composite airplane) was so expensive that a GREAT design was lost to the public (it was fiberglass). The Cirrus SR-22 owes a lot to the Eagle. Very few still exist, but they are treasured by their owners.
For safe use you could use a lot of materials for your wing tip bow. You could probably use wood or a piece of copper water tube (aluminum would be lighter) and be perfectly safe. You would NOT be legal, and if you DIDN'T get the loads right, the tip could fail in flight. Needless to say, DON'T DO IT! Ribs are CERTAINLY structural. Almost every one I have seen was WAY over designed for normal loads, but there are some sneaky loads most people forget about. One is the load from slowly shrinking fabric with "Dope" on it (you will never forget the first time you see Dope on cotton turn a part into a pretzel. I saw a Taylorcraft wing trailing edge that looked like a washboard road from dope shrinkage.). Another is the tooling loads on the part during manufacture. For a lot of parts the design load is the one put on it while it is being built and it will never see that high a load again.
The FAA uses a completely different definition for "structural". They certify airplane parts and if you want to be legal you have to do it their way. We need an official airplane Fed to REALLY define FAA structural. It's too confusing for a lowly engineer like me.
Hank