Tuesday, January 11, 2011

How I build "Rocket Fuel" Bladder Tubes

After taking a huge amount of crap for my bladder tubes made from bi-directional tape I have refined them into a really cool part and saved building time in the process. First find a suitable mandrel, if you are building Streamer Shuttles the bladder tube ends are in the kit and are 1.5", I use a plastic tube from the hardware store. I put a reference line on the mandrel 90 degrees to the end and put it loosely on a stick so I can easily turn it.


Next I wrap clear packing tape sticky side out around the mandrel at an angle that only has about an 1/8" to 1/4" overlapping each time around.


Wrap all the way past the end of the mandrel.


You can be really fancy at this point and draw up some graphics for the tube on the computer. I also measured the size I wanted so they would print on the plastic film. Print.


Here are the sheets for 8 rocket tubes and some graphics in the fill spaces to use up the whole sheet.If you are not going to print the sheets I would imagine any film that is say 4mil or thicker would work here just as well. Just don't use bi-directional packing tape or your buddies with make fun of you...


I pre cut the film to the correct size (that I pre printed on the film) and align it on the reference mark on the mandrel.


While smoothing the surface with your finger to keep out any air bubbles rotate the mandrel working all the way around. I use a strip of tape to attach the overlap.


The part can now be slid off the mandrel with a little twisting and pulling and trim off the excess tape.


Glue the wood caps on both ends, I like the super thick CA for this. Repeat for how ever many Streamer Shuttles your building, say 20... like Kevin.

The tubes are going to be as sealed as you want them to be. The more care you take when gluing on the end caps and sealing the covering to the tube the better the chances of not having fuel in your wing after a bladder pops in the tube.

If you have better ideas, let us hear them in the comments section below.

eles1

5 comments:

  1. Hi Lester

    I you have a hard landing with a full bladder the pressure from the fuel can force the spars apart and destroy the model from the inside.
    If you have some bi-directional tape in stock you might use it to make a “safety belt” for you bladder.

    http://www.f2d.dk/lester/RocketFuelTape.jpg

    Enjoy
    /Henning

    ReplyDelete
  2. Henning thanks for the note. I have seen a few planes damaged in this manner. So even though the tape is longer than the span between the spars it is able to keep them from spreading? I will try this on the next couple of planes to test.

    Thanks for commenting on the blog!!

    eles1

    ReplyDelete
  3. Really nice work. Lester is taking f2d planes to a new level!

    ReplyDelete
  4. The "plastic tube" looks like sink drainpipe.. should be easy to find.

    Any reason not to put the plastic sheet on the inside and the tape on the outside? Also, there's fluorescent light protector tubes - the larger size might work for this.

    ReplyDelete
  5. Yes the bladder tubes are 1.5 inches ID.

    No reason that wouldn't work

    The tube proctors work fine but they are a bit heavy.

    eles1

    ReplyDelete