16 replies to this topic

[ElliotHC]

Does anyone know where I can get thick (2.5-3mm) paper 24mm OD rocket tubes?

[Mortartube]

What I.D do you want? What size is your drift?

[ElliotHC]

Hi,

The ID is 18-19mm and the OD 23.8-24mm, not sure what you mean by drift..

[Mortartube]

The drift is the rod that you will use to compact the powder into the tube. Why don't you roll some? Lining paper from B&Q with slighty watered down PVA glue makes a good job. Tube rolling is a skill well worth learning.

Cover the rod you will roll them on, with strips of PVC insulating tape, running down the length of the rod (One layer thick). This will allow for shrinkage of the tube when it dries. Remove the tape and use the rod for consolidating your compositions.

I assume that you will be making rockets.

[dr thrust]

a drift, also called a rammer would be a piece of round bar either wood, aluminum, brass anything none sparking to press the rocket propellant into said cardboard tube, unless that is your casting the propellant? what are you making?
dam motartube beat me!

Edited by dr thrust, 06 December 2011 - 10:39 PM.

[ElliotHC]

Hi,

Thanks for all the tips, yes I'm making rockets.. Well, rocket motors.

I will be compacting the nozzle then with a plug pooring in the propellent mix as a melted liquid.

I'll give tube rolling a try as I am trying to do every aspect of designing and making the motors as possible.

I've got the cat litter and a coffee grinder, I'm currently modelling the block and nozzle moulds ready for milling.

Edited by ElliotHC, 07 December 2011 - 09:18 AM.

[ElliotHC]

I guess that usually people here are not so interested in the OD as the rocket wouldn't have to go in anything, I will have to keep checking the OD as I wrap the paper. What amount of shrinkage should I expect on the outside?

[megabusa]

The drift is the rod that you will use to compact the powder into the tube. Why don't you roll some? Lining paper from B&Q with slighty watered down PVA glue makes a good job. Tube rolling is a skill well worth learning.

Cover the rod you will roll them on, with strips of PVC insulating tape, running down the length of the rod (One layer thick). This will allow for shrinkage of the tube when it dries. Remove the tape and use the rod for consolidating your compositions.

I assume that you will be making rockets.

If you mean wallpaper lining paper, in my experience, I have found it to not be strong enough for rocket tubes, the pressure builds too high & the tube bursts into many fragments.

There has to be something stronger in there with a 'grain' such as Kraft. Even newspaper makes stronger tubes than wallpaper lining paper.

I use just 30cm of wall lining paper as the first bit on the drift, as it makes it easier to remove. The rest is Kraft or newspaper layered with fibreglass tape, depending on what it will be used for.

The ones with fibreglass are for rockets & are 19mm ID & 3mm wall thickness. They are light & extremely strong.


Phil.

[whoof]

pooring in the propellent mix as a melted liquid.

Im curious, what is the propellant ?

[ElliotHC]

Paraffin wax and something else it's very experimental.

[Sparky]

I'm guessing you are into hobby rocketry with the OD being so specific. The idea of ramming home BP to fill the motor casings fills me with dread. I like the idea of casting them!

Am I right about your intention being for a model rocket?

[ElliotHC]

Hi Sparky,

Yes that is what I am doing with the rocket motors, casting seemed like the best way to do it. It's safe and you get a nice steady burn.

[ElliotHC]

I've designed a block with holes and some nozzle moulds, also the compacting thingy which has a divergence angle for the inside of the nozzle. A local firm is going to knock them up in stainless steel.

[Arthur Brown]

Don't EVER assume a pyro compound is safe.

It's a very relative state, and ALL pyros and comps have the possibility to cause harm. Everything is part of your safety procedure. Remember that if it burns (ie propellant) it burns better when hot so casting has hazards too. Consider melting your castable material over warm water so that there is no flame present, don't let any sparks happen near the fumes of molten wax.

[ElliotHC]

Thanks for the tips, safer but not safe by any means, electric hob a non-stick pan and a wooden spatula..

Just to update, I've cooked up a mix and it burns really nicely, next I will test it in a spent motor tube as it already has a nozzle and is pretty well made to start with.

Launch on Saturday so I'll try a refill then, results are very good so far.