Fiberglass airplanes have a bunch of neat features, one of which is that antennas can be buried inside the airframe, and I am taking advantage of that feature. Trouble is that then you have to be careful about where you put long pieces of metal, lest your radio's speech and hearing be messed up.
Anyway, push/pull tubes of fiberglass instead of aluminum alloy are indicated in several places. So, how to build them? I am asking for any of us amateurs who has tried to build these things to answer back with words of wisdom, preferred methods, etc. I was thinking in terms of both table rolling and braided tubes to get higher stiffness in the axial direction.
One of the things that is easy is a source of mandrels for 1.5" ID Tubing – used fluorescent light tubes. When the part is done, just flex it and the glass mandrel falls out in pieces. My elevator linkage is currently two 81" long push/pull rods with an idler in the middle, so a 1.5" ID tube has got to get pretty thick to get enough EI, so I want more like a 2" tube. Anybody know of any ready sources for 2" - 2 1/2" mandrel or paper tube 7 feet long?
What I know from people who do this as a business (besides the fact that their parts are heavy and pricey):
ICE table rolls from cloth, and everything is +/-45 degrees. They are heavier than aluminum for the same mission. They use a permanent mandrel, heavy layup on one end, and a big hydraulic machine to pull the mandrel from the part, and the part has to be sturdy enough to survive the mandrel pull operation;
MGS and K-Mac are pultruded tube, quite heavy. MGS is claiming an E of only 2.5 Mpsi. News is still out on K Mac;
A*P Technology braids fabric tubes and sells direct. Aerosleeve sells A&P tubes. Soller also has braided tubes. They recommend pulling their tubes over a mandrel, but Aerosleeve has a way of using Mylar film to allow use of a permanent mandrel that might work for long tubes – anybody tried this? Most of Aerosleeve customers are building model rocket tubes, and thus are not as slender as what I am taking about;
So, have you got any experience with these things? Or am I to be a pioneer and get to report back on all of the failures and the few successful methods? Thanks!
Billski
Anyway, push/pull tubes of fiberglass instead of aluminum alloy are indicated in several places. So, how to build them? I am asking for any of us amateurs who has tried to build these things to answer back with words of wisdom, preferred methods, etc. I was thinking in terms of both table rolling and braided tubes to get higher stiffness in the axial direction.
One of the things that is easy is a source of mandrels for 1.5" ID Tubing – used fluorescent light tubes. When the part is done, just flex it and the glass mandrel falls out in pieces. My elevator linkage is currently two 81" long push/pull rods with an idler in the middle, so a 1.5" ID tube has got to get pretty thick to get enough EI, so I want more like a 2" tube. Anybody know of any ready sources for 2" - 2 1/2" mandrel or paper tube 7 feet long?
What I know from people who do this as a business (besides the fact that their parts are heavy and pricey):
ICE table rolls from cloth, and everything is +/-45 degrees. They are heavier than aluminum for the same mission. They use a permanent mandrel, heavy layup on one end, and a big hydraulic machine to pull the mandrel from the part, and the part has to be sturdy enough to survive the mandrel pull operation;
MGS and K-Mac are pultruded tube, quite heavy. MGS is claiming an E of only 2.5 Mpsi. News is still out on K Mac;
A*P Technology braids fabric tubes and sells direct. Aerosleeve sells A&P tubes. Soller also has braided tubes. They recommend pulling their tubes over a mandrel, but Aerosleeve has a way of using Mylar film to allow use of a permanent mandrel that might work for long tubes – anybody tried this? Most of Aerosleeve customers are building model rocket tubes, and thus are not as slender as what I am taking about;
So, have you got any experience with these things? Or am I to be a pioneer and get to report back on all of the failures and the few successful methods? Thanks!
Billski
