Documenting my rocket build

Moderator: Mike Everman

Post Reply
Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

Documenting my rocket build

Post by Zippiot » Sat May 20, 2006 1:27 am

While I await the propellant to arrive I might as well build a test mule huh?

Made a trip to tap plastics, and found a good highschool friend of mine working; he hooked me up with 3 yards of 4.7 ounce (14 inches wide) carbon fiber for 6 bux!!! Also gave me some great cardboard tubes for the body.

Tonight I will take many pics of the beginnings of construction, I plan on fabin' the nose cone and most of the body tonight, motor mounts this weekend.

Rocket should be able to accept 29mm motors in the d-g class range, or that is the plan so far.
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: Documenting my rocket build

Post by Zippiot » Sun May 21, 2006 10:45 am

Vacuum/vacume bagging is a tricky thing...never have I ever seen a very sturdy carboard tube completely collapse inside the bag!!

That tube and bacth of carbon fiber is scrapped...I might have to pick up some polycarbonate or solid acrylic tubing for the job.

No idea how much Hg the pump was pulling, I will try to take a measurement.

Well I'll take another crack at it tomorrow, meanwhile I will start making a mold for the fin canister.

The digital camera is outta town until tuesday, I have some pics on my celll but I wont get up some of the collpsed tube until tuesday...
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Ray
Posts: 187
Joined: Thu Nov 11, 2004 12:48 am
Antipspambot question: 0
Location: Washington State, USA

re: Documenting my rocket build

Post by Ray » Mon May 22, 2006 12:07 am

Try pulling the bag down the inside of the tube, then wrapping it back around the outside...that way it clamps only the tubing and doesn't have the ability to collapse the tube.

Works well for me.

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: Documenting my rocket build

Post by Zippiot » Mon May 22, 2006 12:18 am

That sounds great!!

I am used to vacume/vacuum (finding many different spelling on the web) sailboats and boards, so sticking an item isnide an actual bag is new to me...

Most sites say plug the ends so the bag wont creep inside, do you have a pic of your technique so I dont ruin another batch of cf?
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Ray
Posts: 187
Joined: Thu Nov 11, 2004 12:48 am
Antipspambot question: 0
Location: Washington State, USA

re: Documenting my rocket build

Post by Ray » Mon May 22, 2006 3:53 pm

Sorry, no pictures, but if you use your imagination you'll get the idea. Basically you are bagging only the walls of the tube, not the whole tube. You'll use twice as much bag for any given project, but the results are MUCH better.

You pull the right side out bag through the middle of your tubing, then turn it inside out and back over the outside of the tubing. Seal the ends together and pull the vacuum on only the tube walls.

I did a 12" Carbon Fiber/Kevlar/Fiberglass tube this way. Like you, I lost the tube and material on the first pass. When I did the calculations on how much pressure I was exerting on the tubing, it came out remarkably high...18000 pounds at 20 inches of vaccum.

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: Documenting my rocket build

Post by Zippiot » Mon May 22, 2006 7:06 pm

I think I'm getting like 5-8 inches of Hg...

Back to tap plastics to get a different sized bag!

How many layers of Composite do you use? With sailboat/boards you fill a gap and sand it down, weight is no issue. But a rocket needs to be light and strong.
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Ray
Posts: 187
Joined: Thu Nov 11, 2004 12:48 am
Antipspambot question: 0
Location: Washington State, USA

re: Documenting my rocket build

Post by Ray » Mon May 22, 2006 7:43 pm

tell me more about the bird...is this the one for G powered motors?

What diameter is the tubing, what's the wall thickness, etc.

You may not even need to wrap it. G motors are relatively small and don't load an airframe like a K motor.

Details, man, Details.

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: Documenting my rocket build

Post by Zippiot » Mon May 22, 2006 8:16 pm

Well I have some thick cardboard tubing and sum thin stuff, both with a diameter around 1.5-1.8 inch id. I wanted to reinforce the thin stuff as its wall is 2mm thick and the thick tube is 3.5 mm thick.

Actually it is just going to be the test mule rocket, I have a near finished G class KNSU motor and am starting 3 differently sized composite motors (E F and G). 29mm motors and a neat little system I made so that the rocket accomodates all 3 sizes.

The cardboard is pretty sturdy on both, but I wanted to reinforce it incase an ejection charge doesnt go off...but I guess if the parachute doesnt deploy a little kevlar wont help a whole lot.

The cardboard is pretty heavy, so I doubt the rockets will get too high.
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Ray
Posts: 187
Joined: Thu Nov 11, 2004 12:48 am
Antipspambot question: 0
Location: Washington State, USA

re: Documenting my rocket build

Post by Ray » Mon May 22, 2006 8:46 pm

I don't know that I would spend too much time re-inforcing the tubing for the rockets...you'll just add strength and weight that you don't need. And substatially increase the amount of time you spend on the bird. You won't want to lose it.

Build them cheap and tough, but don't spend much time on them.

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: Documenting my rocket build

Post by Zippiot » Mon May 22, 2006 10:07 pm

Good idea, I'll give it a nice paint job to make up for its shotty construction.

Well now that I'm dont with the main body tube, its time to make a nose cone and fins, plus glue in the motor mount.

The camera gets back tonight so I can make some pics of the crushed tube and the rest of the construction. I used to make the kits this is my first completely scratch build and I wanted it to be strong, all money spent will just go away when it lands in a tall tree.
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: Documenting my rocket build

Post by Zippiot » Mon May 22, 2006 11:18 pm

I do have some nice tubes from wrapping paper, but those would definately need to be reinforced.
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Post Reply