[SS2S-Main] Re: Sugar Shot Weekly Activity Report - Dec.16-20, 2013

  • From: Ben Brockert <wikkit@xxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Wed, 25 Dec 2013 17:47:29 -0700

On Wednesday, December 25, 2013, Cliff Bates wrote:
>     I kind of wonder about the terrific amount of build up of slag in the
> diversion part of the exhaust nozzle however.  It would appear that in
> flight if this happened it could cause a considerable yawing in the
> trajectory.

On APCP solids it's been shown that the addition of a small amount of
silicone oil will dramatically reduce slagging. It's also a powerful
anti-foam agent, and may help to reduce bubbles in the propellant.

>     Also it appeared to me that the exhaust velocity was noticeably lower
> than normal.  But I'm kind of negatively bias on this diffusion plate idea
> anyway.

Measuring the chamber pressure before and after the plate would give a good
idea of how much it's hurting thrust, but it's also something that could be


>     Cliff
> ----- Original Message -----
> *From:* Jeppe Locht, Mainstage Co.
> *To:* sugarshot@xxxxxxxxxxxxx
> *Sent:* Wednesday, December 25, 2013 1:37 AM
> *Subject:* [SS2S-Main] Re: Sugar Shot Weekly Activity Report -Dec.16-20,
> 2013
> And the prize for showing remarkable restraint despite fair reason to go
> ballistic, goes to Rick ;-)
> On Dec 25, 2013 03:52 "Rick Maschek" <rickmaschek@xxxxxxxxxxxxxx> wrote:
>  Eric,
> I can appreciate your comment. I could easily have left the four failed
> attempts out of the video and made it look like things went wonderful. I
> know many that try not to show things that don't work.
> This was the first time we did this type of motor. The tops of the grains
> were inhibited with polyester resin and a layer of pyrogen was
> painted across the top and down the two sides of the grain. During motor
> assembly, the floating nozzle slid forward and cracked the igniter's bridge
> wire, this was discovered after the first attempt and inspection of the
> igniter. On the second attempt with a new igniter, continuity was lost. On
> the third attempt, the igniter was not of sufficient intensity to ignite
> the pyrogen painted on the top surface. On the fourth attempt, a larger
> igniter was used and managed to burn the pyrogen painted on the top
> inbitited surface (seen in the 4th picture of the video) but failed to
> continue to burn down the sides of the grain. On the fifth attempt, a 0.125
> thick slice of APCP propellant was cut from a 38mm grain and the igniter
> place in its center. That ignited the motor. This small K-class motor was
> to test this very thing, how to ignite these grains, would the sliver
> catcher work, and would this grain geometry burn as predicted. We were
> successful with these three things. A new bulkhead and igniter design has
> already been machined that should solve this problem.
> If you look at our many previous videos of motor tests, you will see we
> have nearly 100% ignition on the first attempt. Thank you for your comments.
> Rick

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