I went to friends house and TRIED to build a 12" diameter tube for a rocket! His comments are copied below along with some links to pictures...
I talked Ray Stoner and Bob Yanecek into coming over and helping me lay up and vacuum bag the 12†diameter by 48†long body tube for Skeeter Eater Beater (23X mosquito) today. It took us about 3.5 hours from when we started to cut the fabric. Bob took over 70 pictures of the process while being the dry hands part of the team – Ray and I did the actual lay-up. I have uploaded four pictures to NW Rocketry and here is some description.
The first shows the placement of 3†wide Kevlar tape around the upper end of the tube to help prevent any zippering. There is already one layer of 6 oz glass on the bias and a layer of 6 oz carbon fiber in place. The carbon fiber was much easer to place than the glass.
Tube with Carbon fiber
The second shows some nice resin bleed out through the porous release film into the breather (quilting bat). We used 32 oz. of West Systems 105 + 206 for about 49 sq ft of 6 oz / sq yd cloth and tape (32.7 oz nominally).
Resin bleed out.
The third picture shows the cardboard tube that was being used the keep the 4 ¾†particle board disks apart that were used to reinforce the 12†builders tube that served as a mandrel for the tube build. We had not included the axial loads due to the vacuum – a 12†disk has a surface area of 113 sq in and this was at about 5†of Hg – about 280 lbf.
support tube
We replaced the cardboard tube with 3†heavy duty ABS pipe and resealed the bag (the tubular bags from Mr. Fiberglass and economy seal tape work great). Everything was going great, 10, 15, 18 in of Hg and then – THUMP. The tube buckled and imploded. After cleaning out our pants, we tried to beat the tube back round and use a section of bagging material as a balloon to push it back round using the pressure side of the pump (it does not work).
big oops
OK, so now I get to order more carbon fiber and Kevlar tape along with reprepping a 12†builder’s tube. We learned a lot along the way.
With the tube well supported it was fairly straight forward to place the cloth with two people doing the wet part and one handling dry goods and pictures.
A rotary cutter works very well to cut the fiberglass and the carbon fiber – not so well on the Kevlar.
The biggest thing is that a great deal of internal support is necessary when vacuum bagging a large tube. The next version will use ¾†plywood disks rather than particle board. In addition, I will run stringers along the length of the tube to tie the disks together and support the outer builder’s tube – 8 2x2 stringers should work well.
What did you do with your Monday off?
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Rocketdork
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My wife took me out on Sunday and we went to Matress Land.
We spent Monday waiting for our delivery... the Simmons Beautyrest World Class Exceptionale. It was normally $2,699 but we got it on sale for $1,599.
OMFG!!! For my back, this is the best thing ever! Of course, we had to buy new sheets (because the new matress is over 15" deep). Let me tell you... those are a bitch to find for less than $100.
Sleep... it's nice.
We spent Monday waiting for our delivery... the Simmons Beautyrest World Class Exceptionale. It was normally $2,699 but we got it on sale for $1,599.
OMFG!!! For my back, this is the best thing ever! Of course, we had to buy new sheets (because the new matress is over 15" deep). Let me tell you... those are a bitch to find for less than $100.
Sleep... it's nice.
