Stuck body tubes

[stevethecontractor]

I have an 8" diameter stretched pterodactyl with an eBay.
I cannot, with two adults get the body tubes/couplers to separate.
Any suggestions? It has an automobile paint job so it could chip if I tried to pry it.
Thanks
Steve

 

[David_Stack]

Small BP charge fed up through the motor mount tube (with the tube blocked off after insertion of the charge)?

No different than an apogee ejection charge. Start undersized in the event that the airframe is really stuck and does not want to come apart...

 

[rcktnut]

Cardboard tube?? High humidity? I would try warming it with a hair dryer then try pulling apart, with twisting motion.

 

[MarsLander]

Small BP charge fed up through the motor mount tube (with the tube blocked off after insertion of the charge)?

Use a motor casing with a standard forward closure. Feed the ematch through the front and rear closure leaving the match in the charge well. Put in BP, Dog Barf and tape off. Insert into the rocket and add your motor retainer. Fire the ematch with a launch controller.

 

[Antares JS]

This has worked for me, it might for you if the rocket is not too long.

-Get a long, thick dowel, insert it up the motor mount until the end of the dowel is up against the e-bay bulkhead. Make sure a decent amount of dowel is still sticking out the back.
-Throw the rocket down on the ground tail first. The dowel should slam into the ground and hold the top part of the rocket up while allowing the bottom part to slide off. Catch it before it actually tips over.
-Repeat until top part comes off.

 

[rcktnut]

This has worked for me, it might for you if the rocket is not too long.

-Get a long, thick dowel, insert it up the motor mount until the end of the dowel is up against the e-bay bulkhead. Make sure a decent amount of dowel is still sticking out the back.
-Throw the rocket down on the ground tail first. The dowel should slam into the ground and hold the top part of the rocket up while allowing the bottom part to slide off. Catch it before it actually tips over.
-Repeat until top part comes off.

Was just going to suggest that also. I wouldn't use a charge unless all other methods fail. Even then outcome might not be so good!! Sticking could be due to humidity or powder residue build up.

 

[lr64]

If humidity is the problem, maybe putting a bunch of desiccant inside might help. Keep in a plastic bag. I understand that baked bentonite clay is a good dessicant, i.e. cheap kitty litter. Also, expensive kitty litter. And a bunch of other things, too. Calcium chloride, I seem to recall. Any damp desiccant should be baked first, of course. I suppose the dessicant should be in a bag or other ventilated container to keep it off any surfaces of the rocket. This might take a few days. If humidity isn't part of the problem, then of course this wouldn't do any good.

 

[KenECoyote]

Four adults!

The problem here is that you don't want too much force crushing or marring the finish, but you need more grip. Just double the hands gripping the two sections and direct everyone to be careful.

 

[troj]

Since it's a Pterodactyl, an important question is what airframe material is it?

Is it phenolic, or is it quantum tube? If it's the latter, then your issue is possibly different thermal expansion coefficients between the quantum tube and the phenolic coupler. If that's the case, getting it warm may help - the quantum tube expands/contracts more than the phenolic does.

 

[lr64]

Four adults!

The problem here is that you don't want too much force crushing or marring the finish, but you need more grip. Just double the hands gripping the two sections and direct everyone to be careful.

Hmm....
One could wrap it with many layers of kraft paper, applied with rubber cement. Then glue something to the kraft paper to pull on. Something that can be cut off later without damaging the paint underneath.

 

[jmasterj]

Since it's a Pterodactyl, an important question is what airframe material is it?

Is it phenolic, or is it quantum tube? If it's the latter, then your issue is possibly different thermal expansion coefficients between the quantum tube and the phenolic coupler. If that's the case, getting it warm may help - the quantum tube expands/contracts more than the phenolic does.

It's phenolic based on the size.

 

[KenECoyote]

Hmm....
One could wrap it with many layers of kraft paper, applied with rubber cement. Then glue something to the kraft paper to pull on. Something that can be cut off later without damaging the paint underneath.

At one point I thought of something like that, but using blue masking tape first.

 

[SkyFire]

Strap wrench has worked for me.

 

[stevethecontractor]

Thanks everyone. It is phenolic.

So I tried the BP and it was a miserable failure, so I upped the quantity and it actually kicked back then casing I used . I used an AMW 54 casing plugged and put the bp on thru a vent hole.
I tried the dowel option and got only 1/4 inch.
So I am going to bring it into a cold ac room as I suspect swelling is what's going on.

Steve

 

[bschultz32]

What I'm about to type is about prevention, not fixing this particular case.
Some of my rockets fit tight. I spritz a little powdered graphite around the inside diameter of the tube every time I prep for flight. Then I rely on shear pins to hold things together until ejection.
IMHO, every rocket enthusiast should have a tube of powdered graphite in their range box. Just a couple bucks at most any hardware store.

 

[rtornatzky]

baby powder (talc) also works well as a lubricant.

 

[SkyFire]

Baby powder today is cornstarch which absorbs moisture.
Pure talc (still available) works better.

 

[terryg]

Two strap wrenches and four people two to hold and two to twist.