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-   -   Plastic propellant motors? (http://www.oldrocketforum.com/showthread.php?t=16867)

blackshire 10-04-2017 09:41 PM

Plastic propellant motors?
 
Hello All,

Has any model rocket company ever tried plastic-based (as opposed to synthetic rubber-based) solid propellants? The British produced LAP (Light Alloy [casing], Plastic [propellant]) military rocket motors in large quantities for decades, and many of them were used in Australian sounding rockets at the Woomera Range. The binder-fuel used in the LAP and LAPSTAR motors (“STAR” referred to the shape of the propellant grain void) was polyvinyl chloride (PVC) plastic. Polyurethane plastic (such as the polyurethane casting resins) could also be used as a fuel-binder. Also:

Such plastic propellants might work well in the same parallel-wound, rolled-paper motor casings that are used for black powder model rocket motors, as the liquid propellant—before it cured into a solid—would bind itself to the inner casing walls (clay or phenolic nozzles could be used in such plastic propellant motors). I had noticed that the polyurethane casting resins, when spilled (or deliberately poured) on cardboard or card stock before the mixed liquid resin cures, soaks into the upper layer of the material and bonds to it tenaciously.

Jerry Irvine 10-05-2017 07:43 AM

I have made PVC Arcite propellant motors for the military for space borne uses. Had my motors not been summarily decertified by TRA without cause and without the legally prescribed burn down period in about 1993 I would have started making our then certified nozzle less motor with a variant of Arcite and later reloadables would follow along.

CTI uses a thermoplastic and they have a production capacity several times that of Errortech as a result.

cite:
http://v-serv.com/usr/motors/H90nozzleless.htm
http://v-serv.com/usr/NAR-TRA-93.2.htm

blackshire 10-06-2017 07:27 AM

Quote:
Originally Posted by Jerry Irvine
I have made PVC Arcite propellant motors for the military for space borne uses. Had my motors not been summarily decertified by TRA without cause and without the legally prescribed burn down period in about 1993 I would have started making our then certified nozzle less motor with a variant of Arcite and later reloadables would follow along.

CTI uses a thermoplastic and they have a production capacity several times that of Errortech as a result.

cite:
http://v-serv.com/usr/motors/H90nozzleless.htm
http://v-serv.com/usr/NAR-TRA-93.2.htm
Your bureaucratically-blocked, plastic propellant hobbyist rocket motors gave me a few ideas (which I'll get to below), but first:

To "Physician, heal thyself" should be added the admonition, "Regulators, regulate thyselves" (before even *considering* regulating others--the recent stupid Food and Drug Administration ruling, that a bakery couldn't list "love" as one of their products' ingredients, is a case in point...). PVC Arcite--that sounds like one of Atlantic Research Corporation's solid propellant formulations (if it is, TRA's action was even more senseless, as such a "recipe" is surely very well proven after so many years and motor firings). Even NASA's (it may have been the N.A.C.A., soon before it became NASA) Wallops station had developed a successful case-less--and also nozzle-less--solid rocket motor (its slow-burning fiberglass case "burned down" along with the "propellant-formed, shallow cone nozzle," leaving just the payload after burnout). Also:

Good for CTI--such a rigid, yet cast-able, thermoplastic propellant has production and manufacturing consistency advantages over case-bonded (or "liner tube-bonded") synthetic rubber-based propellants. Your PVC plastic propellant could also have other applications:

Formulated ^without^ an oxidizer, it could be used in hybrid rockets and in solid-fuel ramjets. If produced with just enough oxidizer to keep it burning without air (if made very "fuel-rich," that is), the propellant could be used in solid-fuel ramjet/ducted-rocket motors (the low oxidizer content would keep it lit--and thus eliminate flame-outs--when the airflow through the motor was momentarily reduced or became turbulent, such as during sharp turns and similar maneuvers. (This "fuel-rich" characteristic would also make it useful for hybrid rockets whose liquid oxidizers were lower in oxygen than LOX or nitrous oxide, by "making up for" the oxidizers' lower concentrations of--or more strongly-bonded--oxygen.) As well:

By *purposely* using a rather "anemic" solid oxidizer, your plastic propellant would be a safe and effective propellant for use in Jetex/Jet-X/Rapier-type F/F (Free-Flight) and even micro R/C (Radio-Control) model jet planes. Such long-burning, relatively low-thrust jet motors (which might also benefit from your nozzle-less feature, as there would be no nozzle to potentially fail) could be made single-use (a rolled paper, forward-plugged casing might be ideal [the Rapier jet motors are also single-use, forward-plugged paper-cased units, see: http://www.google.com/search?q=rapi...1.0.-ZX0fUY9szI ]) or reusable. (Such "RMS jet motors" could be similar in arrangement to re-loadable composite propellant rocket glider motors, as the jet motors--like the rocket glider motors--would also have no delay or ejection charges). Also like the Rapier jet motors, plastic propellant jet motors could be made in end-burning and core-burning variants, to enable different thrust levels, burning times, and jet model flight characteristics.

Jerry Irvine 10-07-2017 04:34 PM

Most of your non-consumer wishes already came to fruition. The original smokey sam was in effect a nozzle less motor. It had a casing but it was weak. Spiral wound phenolic treated tubing. It had a foam nose cone and tail unit. Dirt cheap. Vulcan was one of the vendors. I think Navy was the primary user.

Our nozzle less motor had two parts:

1. Casing
2. Propellant

Like an A10-0T it used propellant as the bulkhead and the near zero thrust on the bulkhead burn acted as a delay. They were all about 2-3 second effective delays.

If you have a heavy 13mm motor rocket you can use a A10-0T with a 1/8-1/4g ejection charge added with a paper cap inserted with the rear of an x-acto knife. I suggest 3G or 4G BP. It is easier to dispense it volumetrically than by scale.

Tech Jerry

The propellant it used is not listed on the U.S. Rockets "reads" page. :D

Jerry Irvine 10-07-2017 04:50 PM

Quote:
Originally Posted by Jerry Irvine
Most of your non-consumer wishes already came to fruition.

BTW the way you emphasise words reminds me of the style John Cato used on rmr back in the usenet days.

Cite:
http://v-serv.com/tr/

blackshire 10-08-2017 03:44 AM

Quote:
Originally Posted by Jerry Irvine
Most of your non-consumer wishes already came to fruition. The original smokey sam was in effect a nozzle less motor. It had a casing but it was weak. Spiral wound phenolic treated tubing. It had a foam nose cone and tail unit. Dirt cheap. Vulcan was one of the vendors. I think Navy was the primary user.

Our nozzle less motor had two parts:

1. Casing
2. Propellant

Like an A10-0T it used propellant as the bulkhead and the near zero thrust on the bulkhead burn acted as a delay. They were all about 2-3 second effective delays.

If you have a heavy 13mm motor rocket you can use a A10-0T with a 1/8-1/4g ejection charge added with a paper cap inserted with the rear of an x-acto knife. I suggest 3G or 4G BP. It is easier to dispense it volumetrically than by scale.

Tech Jerry

The propellant it used is not listed on the U.S. Rockets "reads" page. :D
I don't modify motors, but competition flyers in other countries often do. Also, a jet motor market niche has opened up, which you could fill with scaled-down Smokey Sams. Dr. Z (Dr. Jan Zigmund) was forced to cease production of his Rapier jet motors (paper-cased, deliberately "weakly-formulated" zinc-sulfur rocket motors) after the Czech government changed their classification from "smoke device" to "firework," which triggered onerous requirements that he couldn't overcome.

blackshire 10-08-2017 03:48 AM

Quote:
Originally Posted by Jerry Irvine
BTW the way you emphasise words reminds me of the style John Cato used on rmr back in the usenet days.

Cite:
http://v-serv.com/tr/
I've heard the name, but know nothing about him.


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