Tube Contraction Issue

The Rocketry Forum

Help Support The Rocketry Forum:

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
My wife lost her Super Batray to a rocket eating grove a few months back. A good friend was able to find and recover it. Even though it had rained several times, the rocket appears to be in immaculate condition. One issue we have found is that the tube have contracted. The diameter is much smaller now. We would like to try and salvage the rocket as is. It's only had one flight.

Does anyone know a method for expanding the tubes?

I've been considering the idea of moistening the inside and using a Tubular balloon. I'm not sue there would be enough force to actually expand it again. Thoughts?
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
13
Is the issue with the nose cone or motor? Or both?
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
Actually it's most prevalent around the a/v bay.
 

RocketFeller

Well-Known Member
Joined
Sep 15, 2009
Messages
1,185
Reaction score
72
Apply CA to both surfaces and then sand?

If you do try to expand the tube, steaming it may be better than moistening it with a sponge?
 

JJSR

Well-Known Member
Joined
Dec 12, 2012
Messages
777
Reaction score
65
If you don't want to sand for ever, you could try peel a layer off the av-bay coupler tube.
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
I'm afraid it may be too contracted to allow for sanding. I've considered that approach, but I believe it may leave the walls too thin. Also of note, for edge protection, we always ca about 3" of the inside of our cardboard tubes. So there's already ca there and the weather managed to force even that area to contract.

It's a long shot, but that may be the approach we have to pursue.
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
If you don't want to sand for ever, you could try peel a layer off the av-bay coupler tube.
That's also a consideration I had not thought of. I could sand the bulkheads and try to peel a layer or two on the a/v bay.

I realize this may be a lost cause, but I don't want to throw in the towel without at least trying.
 

rcktnut

Well-Known Member
Joined
Oct 26, 2009
Messages
1,689
Reaction score
252
Location
Sheboygan WI
I sure wouldn't use a method that includes re-wetting the tube. Moisture is what caused the problem in the first place. Get a drop of water on a piece of paper it wrinkles up. Ever see a cardboard box dry out after being wet? They wrinkle up, it is the nature of paper products.
 

JJSR

Well-Known Member
Joined
Dec 12, 2012
Messages
777
Reaction score
65
That's also a consideration I had not thought of. I could sand the bulkheads and try to peel a layer or two on the a/v bay.

I realize this may be a lost cause, but I don't want to throw in the towel without at least trying.
Usually the coupler tubes are thick enough to allow you to do it, just go slow.
 

mccordmw

Well-Known Member
Joined
Jan 18, 2016
Messages
1,020
Reaction score
49
Location
St. Louis, MO
If it's just a small area that's wrinkled, can you cut that off?

I wouldn't do it myself, but if you want to try re-wetting, I'd try using isopropanol so it will dry better. I don't think a balloon would guarantee an even cylinder along the length of the area you want to reshape. Can you slide a coupler in it when wetted to act as a form?

Also, can you post pics so we can see what it looks like?
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
I'll post pics once I get home. There could also be some coupler swelling.
 

Nytrunner

Pop lugs, not drugs
TRF Supporter
Joined
Oct 15, 2016
Messages
7,830
Reaction score
3,502
Location
Huntsville AL
Hey, Congrats for getting it back!

It was a really good looking rocket.
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
Hey, Congrats for getting it back!

It was a really good looking rocket.
Thank you. My wife built it. I painted it. And it got one whole flight. I warned her to make the nose tight. She didn't listen. But it's home now. That's a start.


Sorry I did t get the pics taken and posted. Had to work late. Then when I got home, life got in the way. Hopefully tomorrow will be better.
 

K'Tesh

OpenRocket Chuck Norris
TRF Supporter
Joined
Mar 27, 2013
Messages
15,618
Reaction score
2,193
I've made several thousand dollars doing balloon art. I'm sure that if the body tube is wet enough, the balloon will have enough force to stretch it. Perhaps too much force.

This is presuming that you are using high quality balloons, and not those dollar store POS balloons. Balloon wholesalers in your area might have a few samples lying around (and save you the cost of buying a bag). Kits you find in bookstores with pumps tend to have pretty bad balloons too, they tend to be printed here in China, sit around in a warehouse for who knows how long before getting loaded on a container ship (and again with warehouses) before being sent around the country. With the heat and moisture, the balloons degrade pretty bad, and are more likely to blow up in your face than allow you to make something out of them. The pumps are typically OK though, and the books themselves can be a gold mine of ideas.

I have to say though, watching the uninitiated try to inflate pencil balloons by lung is pretty funny, so long as someone is standing behind them ready to catch them should they decide to check out their eyelids for a few seconds (it's only happened to me personally once, and fortunately, I was standing in front of some clean Rubbermaid trash bins which broke the fall).
 
Last edited:

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
Well, boys and girls, we have a new issue. Finally got around to breaking the rocket down tonight. And it gets worse. But I'll let you decide.

I managed to get the recovery harness out and sorted. The sustainer has two eye bolts in the forward centering ring. I have a 3' Y-harness that made. The quick links were almost corroded shut. Took me 30 minutes to get them loose.

Drogue and main both look great. Shroud lines are strong and the stitching is tight. Minimal color fade and no tears or burns.

The a/v bay is currently stuck in the payload tube. The bulkheads are stuck in the coupler. I'm going to attempt to tap it out by using a pvc pipe against the bulkhead.

Nose cone is fine, shirt of a few scrapes from either the landing, wind in the limbs rubbing it, or it's recovery from the tree.

I also got my Aeropack 29/38 adapter back. The motor was a DMS so no issue there.

Now the bad part. The motor tube and adapter held water. A lot of water. Removing the motor and adapter literally tore the motor tube asunder. But I did get the retainer off successfully. A little clean up and it'll be viable for reuse.

Two centering rings and ttw fins. What are the chances that the motor tube can be replaced without tearing the rocket apart?
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
Hey Jim. In addition to the balloon, I was looking at lining the tube with a piece of aluminum. Not foil, but actual thin aluminum. The stuff I have is designed to line the valleys of a roof for water running down. It's very flexible along its long edge but still very rigid along its short length when rolled. Just one option I've considered.
 

K'Tesh

OpenRocket Chuck Norris
TRF Supporter
Joined
Mar 27, 2013
Messages
15,618
Reaction score
2,193
Kruegon,

I can't make that call for you. I'm presuming that the aluminum is a temporary thing, and not a permanent thing.

Photos would help show what you are talking about. However, from what you've said, I'd be thinking about tearing it down, and rebuilding it with new tubes. Presuming that the CR's are attached to the fins, you could remove the damaged motor tube, and insert a new one in its place, then redo the internal fillets. Slotting the tube for the fins isn't too hard to do (especially if the fins are flush with the back of the tube, or really close to it). Then you'd install the whole assembly as one unit.

Once you get it right, you might want to seal the inside of all the tubes with some Minwax wood hardener to prevent water damage from any potential future problems.

Just my :2:
 
Last edited:

Incongruent

Well-Known Member
Joined
Oct 25, 2016
Messages
1,735
Reaction score
5
Hey Jim. In addition to the balloon, I was looking at lining the tube with a piece of aluminum. Not foil, but actual thin aluminum. The stuff I have is designed to line the valleys of a roof for water running down. It's very flexible along its long edge but still very rigid along its short length when rolled. Just one option I've considered.
Aluminum flashing?

Also, I don't think you can shape the tube without removing material or wetting.
Paper is made by laying pulp onto screens (to let water run out) and running it through heated rollers to remove the remaining water. If you had a water damaged sheet of paper, you could iron it on low heat and steam to flatten it, (protected by something on either side) but that forms it into a flat shape; I'm not sure how that could be applied to a tube.

I think K'Tesh's tube replacement solution is the best in terms of future durability and quality, but then you have the "If a ship gets all of its parts replaced, is it really the same ship?" problem and have to paint it again...

As for the motor tube, I'm by no means experienced in this, but if after you removed the body tube, you (first) used wood blocks or something to space out the centering rings and C clamp them in (so the fin-CR attachment isn't as strained) then one at a time used a saw, knife, or other cutting tool to slice the middle and front of the motor tube out, (maybe the back, but you might be able to remove the majority of that with pliers) then filed & sanded out the remaining motor tube, you might be able create enough room to slide a new one in.
See if you can find a second opinion or easier suggestion first.
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
Kruegon,

I can't make that call for you. I'm presuming that the aluminum is a temporary thing, and not a permanent thing.
Yes. Just to allow even pressure across the target area.
 

cbrarick

Wildman CT
Joined
Jan 23, 2009
Messages
2,597
Reaction score
318
I bet before you're done fixing everything would take more time then getting a new one. But hey, we're rocket people and have attachments. I'd attack the fin can by pealing away the outside tube after measuring carefully the length of the tube and the location and length of the fins and transcribing it to a new tube. Once the old tube was peeled away, take off the fins and clean up, then measuring and peeling out the motor tube and clean the centering rings up. at that point, new motor tube in, airframe on, fins glued & ready for paint. I'd call it a rebuild - my definition is any rocket that still has an original piece on it is a rebuild. I've got a LOC tweed-B that still has the original fins and retainer after a severe "bonus delay" issue....
 

Kruegon

Well-Known Member
Joined
May 21, 2014
Messages
1,885
Reaction score
4
Ok. I had to violently drive the a/v bay out of the tube. The bay got soaked. During its removal, the batteries shook loose. One of them snapped the programming button off one of the StratologgerCFs. I'll have to see if it can be soldered back on then test it.

The payload section is accepting the nose cone well. The aft of the payload is still slightly damp. I'll have to let it dry and see what happens. The sustainer is too small to even accept a new coupler. The stretching process has begun.

I have inserted a nose cone, point first, into the tube until snug and then pushed a little more. If this is successful, I'll have 1/2" to 1" of insertable length. Next I'll just have to figure out how to extend that three more inches.

The sled is trash. One switch is trash. Part of the wiring may be trash. Testing of the altimeter will have to wait for now.

So considering the start of restretching the tube, any suggestions on how to extend this idea further into the tube? The start seems to be working well if not exactly perfect.
 
Top