[roc-chat] Re: High Alt, Multi-staging, and Balloon Structure

  • From: Mike & Nancy Kramer <kramer@xxxxxxxxxxxx>
  • To: roc-chat@xxxxxxxxxxxxx
  • Date: Sun, 24 Jun 2012 10:40:36 -0700

For the airframe,
Yes there is there is thin carbon fiber cloth. 4oz cloth will be around .006 inch thick with a wet layup, 8 oz will be around .012 thick with a good wet layup. One thing to think about is having a thin ply on each side of the paper / cardboard to make a sandwich structure. Takes some practice but good solid structure.
balloon construction, are you talking about a pressure stabilized tube? If so, by using VERY light ribs and stringers I think you can get a much more reliable lightweight structure. 

Mike kramer

On 6/24/2012 10:22 AM, Richard Dierking wrote:
I got the high-alt bug at BALLS last year. I saw some multi-stage projects attempt to reach high-alt, and they all didn't seem to do too well. For one thing, I think it's difficult to design/build a stable N to M to M kind of rocket. So, many people just build the P, Q, whatever large single stage rocket or reduce the number of stages to two. I have ideas about a 3 stage rocket with strap-ons for the initial boost, and even have done some experimenting, but need some advice. *First, are there specific FAA restrictions on launching high altitude multistage rockets?* Again, I'm not planning minimum diameter, which I understand has some great advantages. But, the method for the strap-ons requires some attachment depth. Additionally, I like the idea of having some through-the-wall fin attachment. So, I plan on using 6" tube with 98 mm mount, and 4" strap-ons with 75 mm mount. To reduce weight on the first stage, I'm thinking about thin fiberglass over paper tube (I would like to use carbon fiber, but honestly, have no experience with this). Then, stripping the layers of paper out from the inside of the tube, adding the motor mount, and being able to pressurize the inside to 5 to 10 psi (over ambient of course) for a strong balloon structure. *Has anyone ever done this for a amateur-type rocket? Is there even such a thing as thin carbon fiber cloth?* 
**
*I would like to try the 1st stage core with balloon structure for my L3 project. Is this too weird? * I've messed around with modifying aquarium check valves and I think I can build a very simple and light pressure regulator to prevent over-pressure of the airframe. Strength must be maintained, and it must be very robust during launch, because I'm also planning on using 3 or 4 strap-ons attached to the centering rings of the airframe.. 
Richard Dierking
Level 2
TRA 11366
NAR 84983

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