Vac chamber for degassing

JR North fired this volley in news:gPWdncarTqmW3bzRnZ2dnUVZ snipped-for-privacy@posted.isomediainc:

You're thinking of Candy fuel. Zn/S heated to the temperature that will fuse the sulfur will start to react immediately -- injuring you.

There are solvents that will dissolve sulfur, but the traditional way to treat Zn/S so it will not break up during thrust is to VERY slightly dampen it with a tiny bit of alcohol (just for processing, to keep down the dust), then pressing it under hydraulics to about 6800 psi on the composition (which makes the sulfur go amorphous, acting as if it had dissolved, but at a much lower temperature). When it dries completely, which takes weeks, it becomes a solid grain than can be lightly machined, and will not break up easily.

But --- WHY? Zn/S has one of the lowest impulse figures of any fuel available. APCP is a strong fuel, inexpensive, easy to make, and fun to shoot.

Despite what a prior poster said, it's NOT "difficult to light". It burns like Hell's Fury with the mere touch of a match. But it was accurate to say it doesn't function by exploding, and has a shallower P/R curve, so it doesn't run away in a casing as easily as some other sorts of propellants.


Reply to
Lloyd E. Sponenburgh
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That's right...long time ago. We used acetone, I think. JR Dweller in the cellar

Lloyd E. Sp> JR North fired this volley in

Reply to
JR North

I agree with the suggestion that a window is a great idea - urethane resins can foam up to triple the original volume and it's nice to be able to use the vacuum valve to control the rise. Not sure about your resin but a window is nice. Go to ebay and search for "vacuum degassing chamber" for some examples made from stockpots with a flat acrylic lid. You can use bain marie pots, too, if you have any steam table leftovers :-). Or PVC pipe with the bottom glued on. Putting the fittings in the flat lid along with an oring groove makes the chamber simple. You can make a seal by making a wide flat groove, greasing the top of your chamber with vaseline, and filling the groove about halfway with rtv silicone. Press the lid gently onto the chamber partway through the rtv so you have contact all the way around and let it cure and presto!, custom oring.

----- Regards, Carl Ijames

Reply to
Carl Ijames

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Reply to
JR North

A guy I watched casting pewter belt buckles at the Amana colonies in IA degassed his RTV in a chamber consisting of a metal plate, some rubber sheet, and a thick glass cake cover.

Reply to
Don Foreman

They are made for both pressure and vac. The pressure is greatest. The heavy weight on top that spins, drops down with the lack of pressure and prevents the air from re-entering the chamber as it cools. It would depend on the specific model if it could be rated to a very low torr value.


Mart>> >>> Getting ready to cast new bumper finials for the Roadster. They are the

Reply to
Martin H. Eastburn

JR North on Tue, 22 Jun 2010 12:58:15

-0700 typed in rec.crafts.metalworking the following:

Decades ago, a prof tried making the AL & Sugar rocket fuel. never got the mix quite right. Usually just produced a massive amount of smoke. Till the time he was asked if he could make a smoke bomb for a college prank (ah, the good old days...). That time, he wompted up a batch in a coffee can, and when the guy lit the fuse -Whoooshhh! It went off like a rocket engine. Fortunately, it was "aimed" down onto the ground. But Tom said it shot out a tongue of flame two storys high, and burned out in seconds. Only time he got it "right".

tschus pyotr

Reply to
pyotr filipivich

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