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The topic of rolled balsa fuselages leads me to ask why?
Kevlar motor tubes are available in sizes fitting P-30, F1G, F1B, and unlimited models.
They may be a little more expensive, but they are much stronger and lighter and withstand blown up rubber motors. Don’t require any covering or finishing either.
I currently have F1G motor tubes, .80″ OD x 15″ long, they taper from front to back by .05″.
Dave,
I think they are fine for smaller models, but when you get up to 34 to 36 inches in length, the balsa is lighter. So, for big unlimiteds, they may get a little heavy.
BillWeight comparison ofr actual costruction.
“Store bought” kevlar tube section.
Length 20″, O.D 30mm tapered to 28mm (Approx.1.2″ to 1.1″)
Weight 25.7 grams / 1.285 gm/in“Home made” rolled balsa/composite tube.
Constructed thus:
0.6 oz. glass “deck cloth” inner layer bonded with epoxy matrix
4′ x 1/16″ 8# A grain sheet balsa core
Polyspan outer layer spirally wrapped after forming with 4 coats nitrate dope
Glass is laminated and cured before forming, chamfered joint bonded with same epoxy as glass (layer of glass lapped in the joint)
Length 36.5″, O.D. 33mm (approx 1.3″)
weight 32.9 grams / 9.013 gm/inThe kevlar tube is much nicer in appearanc and probably much stronger,
You have to figure out how to bond two of them together unless you get the two different sizes available and “nest the joint. Then you’d have a more or lest blast proof fuselage tube aprrox 40” longThe balsa tube on hand is pretty scruffy looking in comparson and I’m sure some of the craftsmen out there can do a much nicer looking and probably lighter weight tube. One piece and no taper thoug, and adequate for the job. Maybe cheaper, maybe not, definitely more time consuming and no shiny bits for accessory parts available.
Cheers!, PeteFor unlimiteds, I use a 1/16 rolled balsa tube. Tissued on the inside and outside. No glass or resin, except a couple inches in from the front and rear. About 18 grams for a 34″ long tube.
Bill,
The first liar never has a chance does he?
The above referenced tube was an experiment to see what was possible.
I was looking for a possible F1B fuselage variation that had a chance of surviving a broken motor.
It sure SEEEMS hell for stout.
I like 18 grams better.
Same 4″ wide sheet?
Tissue: Esaki, Silkspan, or Polyspan?
How applied?
Cheers!, PetePete,
Balsa is 4×34 6 1/2 lb stock. Weight is 14.5 grams. Tissue applied on one side with dope, two coats. Tissue is pre-war white.
The glass cloth is the .56 oz, applied with the thin instant glue then sanded. One coat of dope over that, then tissued. The entire tube, including pylon, carbon wing joiner and aluminum rings front and back comes to 32 grams. These won’t stand up to a blown motor. I have made tubes for wakefields using a method similar to what you described, and the weight/ strength difference is significant. The reason is not due to the covering or balsa, but the epoxy. This adds weight like crazy.
These weights are pretty much in line with other modelers. I know Carl Redlin’s tubes are even lighter. I don’t have the intestinal fortitude to try to get to his weights!.JPG)
Bill,
Thanks.
I had a fair stock of good tissue in the late fifties but sadly, gave it away when I went back to college. The stuff you can get now doesn’t seem to work the same at all.
I’ll try your method and see what I get. It seems that I am continually re-inventing the wheel since returning to Free Flight after a forty year lay-off.
Cheers!Hey Pete, its important to rememberwhen re-inventing the wheel that first improvement over the square wheel was the iriangular wheel.
One less bump per revolution.Hi,
I’ve been lurking around here.
When you use a tube for a body, you do you prevent the rubber lub from getting on the tube?
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