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RDS 2 Stage Nebulous

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matt_taylor

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hey guys
here are few pics of a poject me and Gerry Munden (they only importer of rocket stuff in NZ) have undertaken. This rocket when built will be the biggest ever built in New Zealand, its a 2 stage with both stages having 98mmt's its 22FT tall , does anyone have any tips for attaching fins? as im not sure Carbon fibering them to the mmt will be enoguh. here are some pics
 

matt_taylor

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here is a pics of just the fins, thats a B-6 on top for scale
 

Elapid

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that's a big one!
:D

do the instructions give any clues as to how to attach them?

and along those lines, how do you like the kit?
does it seem complete?
are there instructions, and are they well written?

i'm interested in buying one of their kits, thanks for any info!
 

matt_taylor

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it came with no instructions, im not sure if there smaller kits come with instructions, i really like the kit, its pretty basic, no chutes, only on strap nylon shock cord.

matt
 

Jerry Irvine

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Originally posted by matt_taylor
it came with no instructions, im not sure if there smaller kits come with instructions, i really like the kit, its pretty basic, no chutes, only on strap nylon shock cord.

matt
I am familiar with those tubes and that construction methiod.

I strongly suggest glassing the entire rocket which will also help keep the fins on. The most likely failure mode is still fin inertia ripping them away from the arframe.

Jerry
 

matt_taylor

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yeah i am going to glass the whole airframe, and also use carbon fiber to attach the fins to the MMT, once question is , watweight glass? i think 6oz is to light and i would rather do one layer of say 12oz and a veil of 3oz than 2 layers of 6oz and a veil of 3oz

matt
 

GL-P

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There are places that sell like 40oz cloth for boats and aircraft.

I would personally go for many layers of 6oz cloth. You will get better epoxy absorption. Many layers is stronger than one.
 

kgholloway

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For what it's worth the biggest rocket I've seen that was glassed was an "Ultimate Endevour", at 6" diameter by 108" long, that was built by a friend of mine. It had two wraps of 6oz. fiberglass, no veil, and finished quite nicely.

As for attaching the fins he used his standard method of glassing the inside of the fin can. To do this you cut the fin slots **only** the length of the fin, not completely to the end of the tube. You then glue the forward centering ring to the MMT and glue the assembly into the rocket with the rear centering ring being left loose upon the MMT. The rear centering ring is only used to center the MMT in the airframe until the epoxy on the forward ring sets up.

Once the forward ring and MMT is glued in place you insert the fins through the slots in the airframe and glue the root edge of the fins to the MMT. Now cut a piece of fiberglass cloth as long as the length of the fin root and as wide as the sum of the distance between the MMT and the airframe and the distance between the fins measured along either the inside of the airframe or the outside of the MMT, depending on which joints you are reinforcing. You need to do both, one at a time of course.

Soak the fiberglass reinforcement in a good epoxy like "West Systems". Now it gets a little tricky. You take the well wetted fiberglass cloth and roll it up around a small dowell sized to reach to the front centering ring and still leave enough sticking out of the fincan to hold. Touch the cloth to one of the fins about 1/2 of the way from the MMT to the airframe and slowly unrap the cloth from the dowel forcing the cloth into contact with first the fin, then the MMT or airframe, and finally the other fin. When done the fiberglass cloth should look like a a square bracket "[" with the short legs going up the sides of the fins and the long leg laying along the MMT or the airframe. Repeat this for both the MMT to fin and airframe to fin joints for each of the pockets formed by the fins. This will completely glass the inside of the fin can and create a set of tremendously strong fin joint reinforcements.

Ken Holloway
 

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