[SS2S-Main] Re: Rocket help request

  • From: Ben Brockert <wikkit@xxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Thu, 2 Jan 2014 11:12:37 -0700

Glad to hear from you, Jimmy, it's always interesting to see your projects.

If you do another experiment on this, try adding a small amount of
silicone oil to the propellant; between one drop per kg and 1% by
mass. When burned inside the engine it turns into incredibly fine
silicon dioxide dust that coats the surfaces of the nozzle. The slag
then isn't able to stick, and won't build up; there's been papers
about using it in APCP rockets to reduce aluminum oxide slag on the

It's available from most drugstores in small bottles, intended for
other purposes related to its slipperiness. You can also get it in
gallon jugs from a variety of industrial suppliers because it's used
as an inert liquid for heated baths.

Keeping with one of the themes of sugar rockets, both the oil and the
silicon dioxide are nontoxic. You don't want to inject the oil under
your skin, but it's safe to eat.


On Thu, Jan 2, 2014 at 10:44 AM, James Yawn <jyawn@xxxxxxxx> wrote:
> 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:
> http://www.jamesyawn.net/endburner/
> 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
> jyawn@xxxxxxxx
> www.jamesyawn.net
> 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
>>>> problem:
>>> 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.
>>> -p.
>>> -----
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