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Old Mar 06, 2014, 09:34 AM
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Making a CF "backbone" tube for CF F3P plane

Hi,

I've been watching the Lantsov's thread about his "backbone" CF tube he uses for his extremely light F3P planes. I'm not about to say that this is a substute but it may begin to get some fliers thinking about how to make some light tubes.

Give this some thought looking at the pictures.

1. Roll out the .2oz veil on a clean/ hard/flat surface such as glass take a 3mm steel rod and apply a little contact cement. Take the rod and stick it to the end edge of the veil.
2. Roll the rod up the veil about 60 mm. While it is rolled up heat the veil with a heat gun. The heat will impart a set to the veil and will facilitate rolling up the veil once it is wetted out with epoxy.
3. Un -roll the rod and weigh it down at both ends.
4. Prepare a 5mm x 1000mm length of silicon fuel tubing by blocking off one end with a piece of dowel. Insert a loose fitting steel rod inside the fuel tubing (this will help keep the tubing straight as you roll up the veil). Remove the steel rod from the tubing and blow into the open end of the tubing and pinch off the end to keep the pressure in the tubing ( this will help keep the tubing stiff). Lay the tubing down against the 3mm rod that is attached to the veil.
5. Wet down about 6mm of veil along the entire length of the tubing. Use a sharp #11 blade and cut the 3mm rod from the veil (cut between the rod and the tubing). The veil will wrap itself around the tubing. Wet the veil some more and roll up the tubing for a distance of 100 mm.
6. Keep the veil roll weighted down so that you can work the tubing tight as you roll it up.
7. Once you are happy that the veil is rolled up tightly, cut the tubing/veil roll from the large veil roll.
8. Wax an area of the work surface and keep rolling the wrapped tubing several times to insure the veil is completely wetted with the least amount of epoxy.
9. Wax a clean area of the work surface and lay the tube/veil roll out. Wax a straight edge and set it against the tube/veil roll to keep it straight until the epoxy cures.
10. After it cures, remove the dowel plug from the far end and tape the end of the tube down. Slowly pull on the silicone tubing to remove it from the tube.

This will result in aproximatly a 6 gram tube about 90mm long. . Let the epoxy cure for a week before checking the strength of the tube.

George
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Last edited by Ampbomber; Mar 06, 2014 at 11:21 AM. Reason: more info
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Old Mar 07, 2014, 04:38 AM
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Nice information, I wonder how that metalized Mylar benefits Lantsov's cf tubes
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Old Mar 07, 2014, 04:44 AM
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Quote:
Originally Posted by akfreak View Post
Nice information, I wonder how that metalized Mylar benefits Lantsov's cf tubes
My guess is that it keeps the tube from splitting if the tube is made from unidirectional CF. The veil is not unidirectional. It is made up of a web of CF fibers.

Maybe he will let us know.
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Old Mar 07, 2014, 03:57 PM
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The tube is made of unidirectional carbon in one layer of metalized mylar. Larit resin. One tube weighs 1.3gr Dried under high pressure in the furnace.
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Old Mar 07, 2014, 05:36 PM
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wow!
are the tubes pressurized for cure? or are they cured in a pressurized vessle? (i was thinking pipe would be eazy)
does the Mylar hold the final shape with wet tow inside or are the tubes formed?

thank you!
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Old Mar 07, 2014, 05:40 PM
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Ampbomber

you get the prize for getting to work on this project. emaxmodel.com has cheepish carbon stock for your build.
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Old Mar 08, 2014, 12:40 AM
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Unidirectional carbon resin-impregnated metallized Mylar wrapped in aluminum tube loading Our tubes 800mm
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Old Mar 08, 2014, 03:02 AM
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[QUOTE=mattnat;27721777] (i was thinking pipe would be eazy)

I had the same thought using a small bore tube as a former, also I was thinking that if I were to wrap the wetted carbon material in the mylar that would stop it sticking to the inside of the tube.Then I also wondered if a rubber pipe wrapped in mylar free to expand was inside the carbon that would also stop any sticking there, but all that sounds a bit fiddly and complicated and probably likely to fail.

Arcright
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Old Mar 08, 2014, 03:20 AM
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Guys,

I've posted this only as a thought provoking process. Hope all of you interested in experimenting can use some of this info. Our indoor season is coming to a close in three weeks so I won't get the chance to build with this tube until late summer. Keep in mind that I don't ever expect to build as light as Lantsov does because of the cost involved but I do like to see what can be done on a shoe string budget.

George
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Old Mar 08, 2014, 03:56 AM
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Hi George
Yeah a good idea to get the grey matter churning I wonder just what the material is that morozov is using from his statement "Unidirectional carbon resin-impregnated metallized Mylar" it sounds as if it's a single ply material not a sandwich type as we would have to build.
I would prefer to purchase a couple of his rods as I have found these carbon models to be very robust, I've built two so far one is over 18 months old been crashed plenty of times and other is well over 2 years old and been sold on and still going strong .So I don't think that I'll have to have many of the rods to keep me fly for some time.

Arcright
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Old Mar 08, 2014, 04:29 AM
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Arcright,

I've built a few of Lantsov's CF planes the last few years (not as light by far) but enjoy every on of them. Nobody else around here builds them so they are a conversation piece.

BTW, how much do these tubes cost? Also, Lanstov uses a 6mm "backbone" for his large planes. It's difficult to keep up with what's going on with these carbon aircraft. To me it's dollar to weight that is the challenge. The least amount of dollars invested does equate to a heavier piece but I have to be a happy camper with what I have to work with. If I were into F3P competition and had the money I would buy the best that is out there.

I'm sure more info about the tubes will become avaiable in the future.

George
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Old Mar 08, 2014, 06:00 AM
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Hi George
Yes I'm with you on the money per gram equation.My mark one carbon Clik is 103 grams and flies loverly, the only reason I would like to build another one is I've had a fly of a foam one that weighed 89 grams and it flew so much more slowly.
That was my thinking regarding buying the tubes that once built I'll get a lot of use out of the model.
As you say let's hope more information becomes available as time goes on.

Arcright
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Old Mar 08, 2014, 11:59 AM
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Previously, we have built aircraft using 6mm tube. Now only 3mm. Achieved the minimum weight to 70g. Next year there will be changes to 60g. 71gr full plane flying weight.
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Old Mar 09, 2014, 05:05 PM
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A super light F3P fuselage tube

The technology for making a very light and strong fuselage tube is old stuff. Using this technique as a basis for an F3P tube, it might be possible to make a tube lighter than Alexey's and a lot stronger.

Here's the story:

Indoor freeflight planes for the F1D and Pennyplane classes have used a balsa tube for the fuselage for years. The tube has to support the flying surfaces, the propeller and resist the tension of a rubber motor with over 2,000 turns on it on an F1D model. The attached illustration shows a motor tube at the bottom of the picture with the tube and the bracing required to resist the largest force, that of the motor's tension.

The reinforcing is made of balsa peg/braces that go through the tube and support extremely fine wire made of tungsten or other metallic alloys. A braced motor tube weighs a little over 0.3 gram. Extending the technology for an F3P fuselage tube should produce a tube of little more than a gram and even that might be overbuilt.

Lately F1D flyers have been experimenting with another form of bracing, wrapping carbon or boron fibers on a diagonal around the balsa tube. I'm not familiar with the particulars of the technique but information should be available through <https://groups.yahoo.com/neo/groups/Indoor_Construction/info> or other Google searching. And instructions for making the basic balsa tube are readily available and in detail on about page 99 of the book Building & Flying Indoor Model Airplanes.

The F3P plane in a configuration like Alexey's is actually quite similar that of an F1D model. The carbon fiber frame would be bracing the balsa/carbon-boron tube in much the same way as the F1D tube is braced. I've had extensive experience with Pennyplanes and F1D models and enough flying indoor RC 3D that I have no doubt the F1D type tube would stand up to the rigors of F3P flying.
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Old Mar 10, 2014, 05:45 AM
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Ron,

Very interesting! Thanks for the info.

George
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