35 replies to this topic

[a_bab]

I can aquire some spiral wound supposedly high quality tubes made by a known european supplier. These tubes are 1" internal diam. and the wall thickness could be as much as 1/4" or even more.

My question is if there's anyone with some experience regarding what kind of rockets I can make out of these? Since they are for 3 pounds, the motors will be quite powerfull and I'm afraid even a simple BP (cored of endburner) will fail given the weak nature of the spiral wound tubes.


Any opinions please?

[digger]

I guess that is a tricky one. It depends on all sorts of factors such as what material is being used in the tube manufacture. Is it going to be a few turns of thicker card or loads of turns of 60gsm Kraft?

[a_bab]

Well, I don't know yet. Generally speaking most of these spiral tubes are made with the cheapest sort of cardboard, which happends to be the weakest.

I see lots of people here ranting about the mortar cardboard tubes; I know the'd work for that but I'm wondering weather someone has some experience with everyday spiral wound tubes in rocketry (not specially ordered, but recovered from some other applications such as spools etc).

[Potassium chlorate]

Paralell from these guys works well. Spiral I don't know.

But it would be extremely cool to make some really big rockets, although I'm more of a mortar man.

[Arthur Brown]

The suitability of these tubes really depends on the number available to you and their uniformity! If there are many you can do tests and see what they withstand then use them for that. If they are uniform over the months then you can continue to rely on them. If they are infrequent ore not reliably the same each time then they are not really useable as you can't be certain whether the next one will be the same!

[dr thrust]

yeah thing is, a 3lb'er is a serious motor , ten inch long!, 8 inch core,weighing in at 250g your best bet is to buy the best quality tubes you can, so when it catos (and it will) you can factor out tube quality, and work on the propellant , has the amateur really got time to test, test, test?
no because of the nature of our hobby launching a 3 lb'er with a four inch shell is not something you can do on a regular basis! so you need to make the best you can and not skimp on materials

[digger]

One note on the spiral tubes is that a former regular poster here from the states used to use 3" ID spiral tubes with a 15mm wall for making whistle motors that would lift 10" and larger shells.

If anyone wants any of these tubes I get them for free from where I work as they are just a waste from our robot packing lines.

I am not prepared to post them about the country as they are heavy, but if anyone wants them when there is an event I will bring a few along. There are a few people here who have had a few in the past, I am sure they will testify to their strength.

[dr thrust]

yes, those tubes you get digger are superb, ideal for Clark's fountains, or large bp based fountains of yesteryear? as well.
there super strong but as for putting a stick on it... i think you'd need a very large open space, like a desert!

[Arthur Brown]

Yes Digger's tubes are superb! However I wouldn't like to use one as a rocket as it must land somewhere and the tube and a scale (ie large!) stick will cause serious damage on their descent.

[digger]

Sorry for the confusion, I was not recommending using them as a rocket. Before the boring stuff, I just Don't think that there is a big enough open space in the UK to fire one. I was just suggesting there are a few tubes available for the next meeting whenever that is and that spiral tubes can hold some serious pressure.

For your enjoyment here is a link back to the rather wonderful 3" whistle rocket with a 12" header Clicky Clicky

[dr thrust]

no confusion what so ever pal, i know the quality of your tubes, and its a very kind offer indeed
great video by the way, dont hear much from him these days though

[Deano 1]

I thought this pyro lark was a bit of a hobby thing. Why is everybody talking about buying tubes, whats wrong with making them. Paper, thats all they are, paper. I bet 60% of the people on this forum throw enough paper and card in their recycler every week to make enough tubes to last a year. I use cereal boxes, newspaper, old catalogues and even the wrapper around my fish and chips on a friday night. With a bit of good quality wood glue (not just pva ) you can get some strong tubes with a bit of practice. All my rocket motors are made this way and on inspection afterwards, I could actualy use them again.

[Dagabu]

Hey everyone, I am new here but a few of you may know me from across the pond at APC.

Anyway...

I wanted to chime in on the spiral wound tubes and tell you all about my experiences with them. I started making rockets 20 plus years ago with spiral wound tubes that I got from steel rods that were covered by these tubes. I had no idea what a good deal I had at the time! Anyway, I started out trying BP tooling and they all blew up, I switched to convolute wound tubes and I was able to make them work but the spiral wound tubes still sat in the shop staring at me daring me to try another rocket with them.

Well, they would always blow up until some bloke from APC suggested making nozzleless rockets. I thought he was full of crap and wouldn't listen until one day about two months ago, I tried one and it worked!

A 1" ID tube, 10" long, using both the Universal Hybrid tooling and standard BP tooling shortened to 6" worked just fine (video) and will lift 300 grams to 500' with ease.

-D

[a_bab]

Dagabu, thank you for your input. These are probably exactly the tubes I could get. As I said before, mine can have a wall thickness of about 1/4 inch. (5-7 mm, custom). I always suspected these nozzle less BP rockets can't develop the pressure of a cored nozzled one. And I was hoping these spiran wound tunes would work for nozzle less BP as they do for you and now I have the confirmation. Ypeee!

Could you please post a pic of your tubes? Wall thickness? Amounts of fuel? Were these rockets rammed or pressed?

On the other hand I don't think they'd work for whistle.



@Deano: Hand rolling is the way to go for sure. Especially when aiming for high performance rockets.

[dr thrust]

nozzle-less motor's cato,in fact the perfect motor is just on the edge of a explosion! they can and will, develop high pressures , if you look on my nozzle-less rocket thread sambo had plenty of catos, success is down to a wider core design (similar to whistle) and the availability of a hydraulic press