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

  • From: Richard Dierking <richard.dierking@xxxxxxxxx>
  • To: roc-chat@xxxxxxxxxxxxx
  • Date: Sun, 24 Jun 2012 11:05:12 -0700

Thank you Jack and Kurt for the great info on the waiver.

Regarding Kurt's first question, good point.  But, I like to take
risk trying new stuff.  As usual, I will test along the way.  I'm thinking
a level 3 project with properly weighted upper "stages" to simulate the
stress on the booster.  Kramer knows a lot about airframe design, so I'm
considering ribs and stringers.  Dang, it would be cool to try the balloon
structure.
Again, has anyone heard about someone trying this before?

Richard
On Sun, Jun 24, 2012 at 10:50 AM, Kurt Gugisberg <kurtgug@xxxxxxxxxxxxx>wrote:

> I guess you can save a little weight going with a thin pressurized
> airframe, but is it worth the cost to experiment with such an unknown
> factor considering that it might collapse under the weight of the upper
> stage and/or the strap-ons?
>
> Also, I don't think there is any problem with the FAA in flying something
> like you are talking about.  You do have to submit your plans to have them
> approved (at least with Aeropac) if you are going over 25K.
>
> Kurt
>
> -----Original Message-----
> From: Mike & Nancy Kramer **
> Sent: Jun 24, 2012 10:40 AM
> To: roc-chat@xxxxxxxxxxxxx
> Cc: Richard Dierking **
> Subject: [roc-chat] Re: High Alt, Multi-staging, and Balloon Structure
>
> ** ** ** **** ** 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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> //www.freelists.org/list/roc-chat

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