[SS2S-Main] Re: Rocket help request

  • From: "James Jason Wentworth" <blackshire@xxxxxxxxxx>
  • To: <sugarshot@xxxxxxxxxxxxx>
  • Date: Thu, 2 Jan 2014 18:09:22 -0900

Hello Jimmy,

That sounds encouraging, as a little 'tweaking' should improve the motors' performance (as well as the "smoothness" of their exhaust emissions)--Thank You for this information and the link! I've passed it along to the Jet-Ex-Press Jetex/Rapier forum. Aerotech's D2 reload (which is intended for R/C rocket gliders) uses ammonium perchlorate, and while it's a bit on the large/heavy side for most F/F model jets (although there are some big enough to use it), its thrust and 8.6 second burn time are usable for model jet applications. While I'd rather buy jet motors such as Dr. Z's Rapiers "off-the-rack," making them--if necessary--doesn't appear to be terribly difficult, which is welcome news to Jetex & Rapier flyers.

-- Jason

----- Original Message ----- From: "James Yawn" <jyawn@xxxxxxxx>
To: <sugarshot@xxxxxxxxxxxxx>
Sent: Thursday, January 02, 2014 8:44 AM
Subject: [SS2S-Main] Re: Rocket help request

I just sent a "wake up" message to the SugPro list, and have not seen it back in my in-box. But I did not get a bounce either, not yet. I would love to see that list come back, and it would certainly be an appropriate forum for this discussion.

I did a little experimenting with sugar-propelled Rapier clones a few years ago, and got them to work... more or less. I did not pursue it to the point of making practical motors. Challenges were that burn time was too short (less than 10 seconds, as I recall) and thrust too strong - several times what a Rapier would produce. Another problem is that the combustion of KNO3 with any form of sugar produces a lot of potassium carbonate. In high-pressure motors this product is blown out the nozzle at high velocity and thus atomized into that fine white smoke we all love. Or hate, because in low-pressure motors, it often collects into globs, which are blown out the nozzle in spurts. Hot spurts. Really hot spurts if they hit your skin. This might be a problem for someone wishing to hand-launch their models. Appropriate protective gear might mitigate this problem. Leading me to wonder if an ammonium perchlorate propellant could be induced to burn slowly enough to serve this purpose? It could be formulated so that all products of combustion are gaseous, much like the nitroguanadine used in Jetex motors. But I have only made AP propellant a couple of times, so will defer this idea to those who have more experience.
Oh, I found my page on those experiments:


I hope to see the SugPro list return. I miss those conversations, and the marvelous resource of it's aggregate intelligence. If I can help with that, please let me know!

Jimmy Yawn

James Jason Wentworth wrote:
Hello Peter,

Thank you for replying to my query. Unfortunately, I know nothing about the SugPro list. However, the simulation you described below sounds like just the motor we Jetex/Rapier modelers could use! At the very least, it could serve as a baseline design "point of departure" that we could start with to develop such motors. That will be quite helpful--Thank You very much!

-- Jason

----- Original Message ----- From: "Peter Johansson" <rockets4kids@xxxxxxxxx>
To: <sugarshot@xxxxxxxxxxxxx>
Sent: Wednesday, January 01, 2014 9:22 AM
Subject: [SS2S-Main] Re: Rocket help request

On Wed, Jan 1, 2014 at 3:57 AM, James Jason Wentworth
<blackshire@xxxxxxxxxx> wrote:

Yesterday and today I have received numerous messages on the SS2S e-mail list. I was wondering if anyone here could offer suggestions to solve a

Before we get to that, Is there any news on the migration of the
SugPro list to the new mail server?  That list would be far more
appropriate for this discussion than ss-main.

something similar to this but optimized for model jet use (an end-burner producing 1/10 of a newton or so of thrust, for 10 - 20 seconds or more) would enable Jetex and Rapier flyers in the western hemisphere to enjoy our
hobby with no worries about being unable to obtain jet motors for our
models. Could anyone here suggest propellant formulas for such low-thrust,
long-burning jet motors?

Sugar propellants are generally not suitable for end burners because
it is difficult to get the burn rate fast enough for them to generate
sufficient thrust -- at least for rocketry applications.

However, I just attempted some simulations based on your requirements
and it does seem theoretically possible to hit that ballpark.  A 5mm
diameter grain (about the smallest you want to work with) will produce
about 3/10 N, and 40mm length will provide a 5.4 second burn time.
Total impulse is 1.68 Ns, 42% A.


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