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Author Topic: Tail Booms  (Read 1712 times)
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Sundance12
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MAAC #25680, VE4BDF (amateur radio callsign)

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« on: April 14, 2008, 09:26:42 AM »

I have a number of high grade graphite fishing rods that I scrounged at some point thinking that they would go good in a new design. They are .4375 OD tapering to .250 at the end and are 38 inches long. I want to use them in a Tip Launch design that possibley will be RC but that is not decided. The rods are pretty stiff with some bend. I believe that they would do the job but just needed another opinion.

I think that I can get away with them in a design without too much problem.

Anyone have any experience using fishing rod technology?

Cheers

Sundance12

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Dan G.
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« Reply #1 on: April 14, 2008, 07:16:48 PM »

Hi Sundance,

I do have some experience, but not a lot. Furthermore, my experience has been with glass rods, but I don't thing much changes in the handling.

The main concern will likely be marrying the fibre rod to the rest of the airplane. I didn't have much difficulty attaching the rods to my Nordics, but they didn't have to undergo the rigours of tip-launching.

Of course, only a mechanical bond can be achieved so the type of glue you choose will be important. Perhaps ca can be used, but I didn't try ... I stuck with e-poxy. As you probably know, epoxy, like many other glues, works best as a film. Any thicker and it is subject to fracture due to brittleness (makes you wonder about plastisizers ...).= So, if you anticipate the epoxy to be any thicker, you might consider adding a reinforcement -- some fibre ... I've never tried microballoons, but I understand it is sometimes used.

The key to success will be the surface prep of the rod -- the rougher, the better. Roughing isn't easy because that stuff is really hard, but nothing will stick if it isn't roughed. I used saw teeth. I can't think of anything else that would work better ... perhaps a coarse, slowly revolving, grinding wheel? What ever you try, it will probably involve slow speed to work, since gouging takes a little time to reach any depth -- which will never be much with that stuff.

You can probably expect a slight detachment at the glue edges due to the rod's flexing, which shouldn't progress unless the roughing was inadequate.

Dan. G
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Sundance12
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« Reply #2 on: April 14, 2008, 08:17:38 PM »

Thanks for the tips in construction, issues that I had not considered. I will do as you suggest in my construction.

Sundnce12

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GrahamC
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« Reply #3 on: April 15, 2008, 07:26:24 AM »

The fishing rods you have will probably do the job.

If you haven't already, I would suggest you take some time to review the many design of Mark Drela. He makes all his design details available and publishes them on the Charles River Model club's web site.

http://www.charlesriverrc.org/articles.htm

A lot of his designs use pod and boom - Apogee, Bubble Dance, Aegea, Allegro, Allegro Lite etc. Lots of good ideas and techniques and well worth the time to read through. Some of his designs might be larger than your project but it will give a good starting point to perhaps scale to your needs.

I have used fiberglass fishing rods for HLG/CLG's. Something to keep in mind is that frequently a fishing rod will have a gel coat (usually polyester) to give the rod a nice smooth glossy look. This can be carefully sanded off to the effect of a weight savings. Depends on the rods and I haven't looked closely enough at graphite rods to say that this would apply or not. I am constantly on the look out for broken fishing rods that I can recycle into model parts but so far have not found any graphite ones.

Another source for carbon tail booms are carbon/graphite golf clubs. Suitable sizes and often had very cheaply as broken or discards.

Carbon/Graphite rods/clubs/tubes etc are strong and tough but can be worked easily with coarse sandpaper and files. Getting a good rough surface for bonding as Dan as mentioned is top priority and easily obtained with a bit of for thought and work.

Attached is a photo of a small 8" CLG that uses the tip portion from a broken fiberglass fishing rod.

cheers, Graham
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Re: Tail Booms
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Sundance12
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« Reply #4 on: April 15, 2008, 07:45:36 AM »

My fears about these tail booms are lessening, thanks guys for the input. I will make sure that the connection to pod and boom is rough for a good joint and I will sand off all the clear finish on these rods to make them a bit lighter. They are certainly stiff and solid so I will design the one that is the largest diameter into a tip launched glider. I will keep you posted to some progress.

Sundance12
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