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BP Rocket Spindle dimensions


15 replies to this topic

#1 longwaytofall

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Posted 31 January 2010 - 08:47 PM

I am looking for some dimensions for PB rocket spindles, any size really but would prefer 4oz and 1lb. I have access to a machine shop and would like to make some. I have noticed that spindle sets are quite expensive, if there is enough interest I may be willing to start producing them, I am sure I could do it for a reasonable cost. I would eventually like to get into whistle rockets, but for the time being BP should keep me entertained.
Another question, where does everyone buy tubes from?
Thank you!

#2 psyco_1322

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Posted 01 February 2010 - 12:54 AM

Here is one of the only places to get quality New England Paper Tubes (NEPT)

http://www.hobbyhors...yro_tubes.shtml

If you go view the recent thread titled "Helpful application for sketching rocket tools" You will find a program that will allow you to bring up common bp tooling specs within seconds. It literally would take you less time than it took me to type this. Go check it out, great work done by a dedicated pyro.
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#3 longwaytofall

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Posted 01 February 2010 - 01:29 AM

Hey you are right, that is WAY helpful!
I would like to make my nozzle dimensions a little better though, with a 45 degree convergent and 30 degree divergent angle. Is it possible to have the clay nozzle extending right to the end of the tube? It seems a waste to have a nice divergent section only to have tube going past it which has to hurt the performance. I'll start building some tooling and see if I can make it the way I see it in my head.

#4 dagabu

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Posted 01 February 2010 - 09:41 AM

I am looking for some dimensions for PB rocket spindles, any size really but would prefer 4oz and 1lb. I have access to a machine shop and would like to make some. I have noticed that spindle sets are quite expensive, if there is enough interest I may be willing to start producing them, I am sure I could do it for a reasonable cost. I would eventually like to get into whistle rockets, but for the time being BP should keep me entertained.
Another question, where does everyone buy tubes from?
Thank you!


All of my 3# black powder rockets use reclaimed paper tubes from laminator cores, tape cores or spiral wound mutts I found behind a print shop. These will not hold great pressures without hardening and I will be experimenting with plexi glass and MEK to dip them into this spring to harden them up.

I buy all my 3/4" (1#) tubes from Jim Biersach at Hobbyhorse for my whistles but have a quote coming from Marshall Paper Tube Company this week. They use recycled kraft for their tubes but i am talking to them about using virgin kraft for my tubes.

If I get a good price, I will be offering them for sale to everyone but at a price at least half of what Hobbyhorse sells them for.

D

#5 longwaytofall

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Posted 01 February 2010 - 03:55 PM

Nice!!! I ordered some from hobbyhorse, but I am certainly interested in more. As far as strengthening your tubes, what about some very thin epoxy?

#6 dagabu

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Posted 01 February 2010 - 04:24 PM

Nice!!! I ordered some from hobbyhorse, but I am certainly interested in more. As far as strengthening your tubes, what about some very thin epoxy?


I am sure that Mumbles and Swede will jump in here to explain it better then I can but the hardener (such as acrylic) has to be carried by a very high viscosity solvent to get the material to the inner core of the paper tube or it just sits on the outside like a rubber.

Too much epoxy will build up the size of the tube making it impossible to use a clamshell. I will styart the experimants once it gets above 30 around here..... June?

D

#7 Xtreme Pyro

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Posted 01 February 2010 - 05:12 PM

I am looking for some dimensions for PB rocket spindles, any size really but would prefer 4oz and 1lb. I have access to a machine shop and would like to make some. I have noticed that spindle sets are quite expensive, if there is enough interest I may be willing to start producing them, I am sure I could do it for a reasonable cost. I would eventually like to get into whistle rockets, but for the time being BP should keep me entertained.
Another question, where does everyone buy tubes from?
Thank you!


Mumbles gave me some plans to a good core burner spindle awhile back.
Here's the link to the topic, along with some pictures of my tooling made from the plans provided, hope this helps ;)
http://www.apcforum....s...ost&p=50365
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#8 longwaytofall

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Posted 01 February 2010 - 07:46 PM

If your solvent/reinforcing liquid was thin enough, I couldn't imagine that it would be an issue for fitting it into your clamshells. Could you build plugs that fit into the ends of the tube, and then spray a thin layer of wax over the outside of the tube to protect it? Then you could remove the plugs and apply the glue from the inside, and when it hardens simply heat up tube to remove the wax. You could also apply some wax to the clamshell, and after you soak the tube you could put it into the clamshell and tighten it just slightly, and then allow it to dry. That way you KNOW it will fit, because it is already in it.
I was also thinking, you might be able to get some of the glass fibers they use in fiberglass and grind them down to very small sizes, and then when you roll your own tube, you could apply them to the surface of the paper, so when you soak it in resin later it would become very very strong.

Does anyone have any input as to why a gap is typically required between the rocket nozzle and the end of the tube? I should think that it wouldn't be necessary. As I mentioned before, I would like my divergent section of the nozzle to extend to the very end of the tube so that the flow is not interrupted by tube sticking past the nozzle. I'll give it a go if nobody comes up with any legitimate reasons why I shouldn't.

Xtreme, thanks for the link!

#9 TheEskimo

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Posted 01 February 2010 - 09:05 PM

Skylighter suggest using Minwax Wood Hardener to strangthen tubes. http://www.skylighte...works-tubes.asp
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#10 dagabu

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Posted 01 February 2010 - 09:09 PM

Sorry, I must be missing something. I am not aware of any solvent that would allow the catalyst to cure the base on an epoxy. You can try it but I dont think that you would want to keep the liquid from the outside, more then half your surface is on the outside.

As I understand it, the reason for the nozzle to be inset is two fold. 1.) it gives a small amount of tube at the end that is not under pressure. 2.) It helps protect the tube end.

Personally, I have made tooling that runs to the end but my divergent is about twice the angle as is accepted to capture the thrust as it leaves the motor.

D

#11 psyco_1322

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Posted 02 February 2010 - 01:18 AM

A guy I know through the PGI uses a thinned epoxy bath to dip and harden up his tubes. He first heats the tubes in an oven, then dips them, and stands them on end and bakes dry again. Mind these are only 3/8" tubes, for his whistle rockets. Mind his whistle also output over 45lbs of thrust and will put 3" salutes too far in the air to be enjoyed. He also carbon fibers some tube for higher output engines. These are also NEPTs he uses, special ordered to a specific size.
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#12 Arthur

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Posted 02 February 2010 - 01:39 AM

Look in recent threads by Pudidk for his app for designing rocket tooling -very well regarded.

#13 longwaytofall

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Posted 02 February 2010 - 04:45 AM

I thought any epoxy can be thinned out with acetone? I know the kind normally used with fiberglass, resin, can be for sure. I have seen it water thin before. The reason I suggested protecting the outside is because you said that you were having problems with your clamshell. A long enough soak with a thin enough mixture should soak it completely through, even if the outside is covered.

#14 dagabu

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Posted 02 February 2010 - 10:18 AM

I just bounced the question off a friend of mine, Tom Schroeder who is a chemist and answered the issue this way but with the addition that there are thousands of epoxy's and most are thinned with MEK or Acetone, go figure.

"For fiberglass the resin used is usually a polyester/styrene cured with MEK peroxide and it is not an epoxy."
-Tom S.-

#15 longwaytofall

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Posted 02 February 2010 - 03:00 PM

Ok my apologies, I am used to using regular 20 minute epoxy with fiberglass, as well as resin. If anyone out there is in the HE section, and you get a chance to smell the peroxide catalyst for resin, it smells EXACTLY like AP. Took me a minute to remember where I had smelled it before hahaha.
So would that resin work for your tubes??

#16 dagabu

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Posted 02 February 2010 - 04:02 PM

Ok my apologies, I am used to using regular 20 minute epoxy with fiberglass, as well as resin. If anyone out there is in the HE section, and you get a chance to smell the peroxide catalyst for resin, it smells EXACTLY like AP. Took me a minute to remember where I had smelled it before hahaha.
So would that resin work for your tubes??


You wont like his answer to that question, "I am not really a fan of the idea of soaking tubes to make them harder. I would just purchase better quality tubes if that is what the device required."

Sorry



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