carbon or fiberglass?

[bachsta]

i want to add strength to an estes tube but i want to keep it as light as possible. i would also like to use an aerosleeve. so which type would best suit my goals Carbon, Fiberglass, Or a Carbon Kevlar mix? or should i just make a tube out of fiberglass and carbon aerosleeves or something like that?

 

[rocketsonly]

How large is the rocket? What motor will you be flying it on?

 

[bachsta]

about 25" long with nc and 1.3" in diameter. i want to fly it on 29mm motors

 

[rocketsonly]

For such a small rocket, I think the tube alone would be fine. If you really want a stronger tube though, just put a full length coupler inside (but be sure to leave room for the nose).

However, composite tubings look really cool. I'd personally go with the carbon if trying to style up the rocket.

 

[bachsta]

i just found the weight specs the carbon/kevlar mix is lightest so i think i might go with that but where could i find a coupler long enough and skinny enough?

 

[edwardw]

People greatly underestimate the strength of a good cardboard tube. I have some LOC 54mm tubing that I have flown near mach and never had a problem with it. The only thing I had to do was get a longer coupler to prevent it slopping around. I also have a 38mm minimum diameter rocket that flies on a EX J 900 motor. Some serious kick and never had a problem with the tubing. If your really worried I would first add a full length coupler (Balsa Machining www.balsamachining.com) would be the best bet - easy to do and your not laminating anything. That would be my first choice. I have also seen a lot of club rockets that are 29mm fly fine on G's and H's no problem.

If you want to make your own tube out of fiberglass/carbon/kevlar, remember even composite materials are better when paired with another. Pure carbon tubes, while light and stiff, can lack strength. Fiberglass is strong but not that stiff. Kevlar, in my opinion, just adds weight. I personally like the combination of carbon/fiberglass composite. Much better overall blending of the strength characteristics of both composites to get a better end product.

I'm sure other people will chime in, but that's my opinion on the subject from my experience.

Edward

 

[wwattles]

You can either make one or buy one. You make one by doing a little geometry (yeah, it actually does have a practical use!) and removing a strip from the length of a regular tube so that the OD of the new tube equals the ID of the old tube. Remember that pi*diameter rule? Now you get to use it.

Depending on the size of the tube, Andy might have a full-length coupler for it.

WW

 

[AlexM]

If you are going for a mach buster, then a full length coupler is gonna be to heavy.

 

[bachsta]

looks like a coupler would definetly be cheaper but which would be lighter any composite would add about 5-7oz. would that be lighter than a full lenght coupler? i know id be adding lots of waight if i add something to it but could a stock estes tube actually handle a 29mm F or G? or should i jsut replace the original tube altogether with an loc or similar tube?

 

[edwardw]

I looked in RockSim and had it make a tube from Balsa Machining that was a BT-55 tube and a full length BT-55 coupler. The overall OD is 1.325 and the ID is 1.212. RockSim gave me a weight of 2.7 ounces total on the body tube. I was using cardboard as the material. If you even double that you have something that is under 6 ounces. Not bad. The cost would e $7.75 for both the tube and coupler.

Edward

 

[bachsta]

the reason im asking is i saw red arrow hoobies has a bbII by estes and i wanted to strengthen the bt and turn it in into a mpr bird.

 

[solrules]

build it stock (add noseweight, of course) but put a layer of 1.5oz-2oz glass on the body tube and tip to tip on the fins. Plenty strong for any 24mm motor (including the Ellis Mountain G37). No need to overbuild!

 

[GL-P]

Yeah, glass should be plenty fine in this case.