32 replies to this topic

[Prometheus]

Just seen these  http://www.oliverbro.../copy_of_1.html

 

By the way I prefer 4oz core burners as they take much less comp  (about 16 grams) they still lift a nice header and are much lighter in terms of fallout.

 

Rod

 

I bought a load of the 7 1/2" x 3/4" tubes from oliverbrown but they turned out to be spiral wound, completely useless for core burners, even if they're nozzle-less... these are more expensive: http://www.pyrosuppl...ubes/4520679386 but they are parallel wound and much stronger, I've had good results with 60/30/10: .

. 

[dr thrust]

Very Nice rocket, did you ram or press? And did you use a sleeve

[starseeker]

Starseeker - I've seen very little about using sleeves when ramming. I know they are used a lot when pressing as it is vital but less so for ramming.

I would say that a sleeve is a must,even when i had some nept tubes they still split without a sleeve.I can see your concern regarding possible hazards regarding using them with hand ramming but good techniques should negate this to exceptable levels.

 

Failing this a arbor  press can be bought very cheaply.  

[Prometheus]

Very Nice rocket, did you ram or press? And did you use a sleeve

 

Thanks, I used a 1 tonne arbour press and a split pvc sleeve with hose clamps. The propellant was made with airfloat pine charcoal just screen mixed, didn't bother granulating it, I just held a rag around the top of the tube as I inserted the rammer to prevent it all shooting back out. 

[Sparky]

What composition did you use?

 

Oh and I'm using the same spiral wound tubes. 

[Sparky]

Also how do people use an arbor press to press into 7 inch long tubes. Most arbor presses I've seen aren't large enough to take a 7 inch long tube. Is there one people could recommend?

[dr thrust]

People extend them with threaded bar,http://www.pyrobin.c...arbor press.jpg

Edited by dr thrust, 29 June 2013 - 10:09 AM.

[Prometheus]

I used 60/30/10.

 

This is my arbour press, it has a 10mm steel plate which allows me to adjust the working height. I've since added a wheel bolt to the pinion so I can use a 1/2 drive torque wrench, I think I set it to 90-100 ft lbs. 

 

Edited by Prometheus, 29 June 2013 - 11:56 AM.

[Sparky]

What are NEPT tubes by the way?

[helix]

NEPT stands for New England Paper Tubes - NEPT make pyro tubes in the US, these tubes are probably the best tubes you can buy.  I believe NEPT used to make the tubes for Estes Rocket Motors.

 

The problem with using them in the UK is that after paying postage and import duty they become quite expensive.

[Sparky]

I'm now using the parallel wound ones from pyrosupplies and so far so good!

[michaelp]

Just to add my bit my first ilb rocket cato'd, quite disenchanting especially when the wife is looking and you are seeking moral approval for the time locked away in one's den, the second made it to about 15 feet before calling it a day so i read more and bought a dead blow mallet, Mk 3 and Mk4 both went to heaven quite nicely, being a boy and with xmas approaching jewellery has been got so hopefully santa will bring me a hydraulic press, but in the mean time dead blow is the way to go and i do half a heaped teaspoon full each increment.

 

Oh once above the spindle i put some metal in the mix to give sparkle, wife likes pretty

[pyrothrust]

NEPT are expensive, only relatively though, having used NEPT for some time on 3 and 4 pound motors which are close to the Red line, their is nothing else I would use. I have tried some of the parallel tubes from over here and to be honest they are fine for low power but not much more.and they are not high quality Kraft paper but more chipboard which is fine for the lower power outputs. 

 

 

I have previously tried many manufactures in Europe and none will produce anything other than Chipboard tubes as they are not set up to do otherwise. Thus parallel is only just better than spiral wound as the chipboard has very little grain.

Edited by pyrothrust, 19 November 2013 - 02:35 PM.

[helix]

I would agree that although NEPT are expensive, they are hard to beat - especially when you take into consideration the time and effort involved in making the motor and heading.

 

I don't know if any one else here has been experimenting with waxing the inside of the tubes as per Dave F's method.  Ive been trying this out and have had pretty impressive results.  Using straight 75/15/10 BP on a longer than standard 1lb BP spindle without a CATO.  The motor was pressed to 9000psi on the comp using a hydraulic press.

 

I have one of Peret's test stands and recorded the thrust:

 

http://www.pyrobin.c...1lb rocket .jpg

 

I doubt it would be possible press straight BP on a 1lb motor like this without the wax.

 

If you are having CATO problems its worth a try.

 

Projected height lifting a 4" cannister shell if anyone is interested:

 

http://www.pyrobin.c...b rocket ht.jpg

Edited by helix, 19 November 2013 - 05:08 PM.

[pyrothrust]

Could try wood hardener ,This works well in hardening and strengthening the tube.