[SS-Propellant] Re: SSTS New Member

[Rich Nakka]

Thanks, Rich, for the insightful comments/questions.
I'm providing my comments, although I am sure the other Propellant 
Development Teams members will have their own coments to add:

Rich Hansen wrote:

> Richard,
>
>  
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> I am signed up to both lists, although I haven't received any motor 
> messages other than the sign-up--I presume there is no traffic there yet.
>
>  
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> I have looked at your proposed design for the propellant production, 
> and it looks good.  I do have a couple of questions:
>
>  
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> 1) The heating elements--what type of heating element is envisioned?  
> From the sketch, it appears to be provided by resistive heating from 
> wires surrounding the container(s), and I don't know if this can 
> provide the amount of heat we would need, efficiently.  If hot water, 
> steam, or oil is envisioned, I think water/steam would be the way to 
> go, although we add the associated cost of pumps, etc.
>
First of all , let me  reiterate that the sketch is purely 
conceptual...the actual details are  TBD and to be worked out by the 
members of this team.
It is quite straightforward to calculate the heating power required, and 
it's not really that much. Earlier I calculated approx. 1 kilowatt  for 
a 2 kg batch, and that scales up directly. I would think electric 
heating elements would suffice, although we should certainly consider 
the pros & cons of alternate means of heating.
 

>  
>
> 2) The valve and piping arrangement--what's the word on the slurry 
> sticking to the inside of the piping, or the valves, and clogging?  
> Will depending on residual heat of the slurry be sufficient, or will 
> the pipes need to be heated as well?  What would we do if a clog of 
> some kind does occur, and does the system allow easy, fast, and safe 
> recovery from this condition?
>
Clearly a concern. I would think a combination of thermal inertia (e.g. 
heavy walled pipe) and insulation would work. Active heating could be 
worth considering. The consequence of a plugged pipe must be considered, 
nevertheless, and a rectifying action.

>  
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> 3) Are the valves meant to be automatic or manual?
>
Either, whichever we consider to be the best choice with regard to 
safety & practicality.

>  
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> 4) Are we planning on mixing the precise amount of the constituents 
> for a 2kg grain, and what do we do if a 1.8 kg grain comes out (due to 
> ineffective transfer from the mixing box, ie, sticking to the paddles 
> of the stirrer)?  If we mix more than we would need, are there any 
> concerns about the residual amount from the first batch being mixed in 
> with the second batch (none come to mind immediately)?
>
Each of the twelve grain segments will  have a mass of approx. 34 kg. As 
such, several batches will be required to produce a single grain 
segment. Residual material should not matter, as this won't affect the 
propellant ratio for subsequent batches.

>  
>
> That's all that comes to mind now--these questions may have already 
> been answered, or are irrelevant for one reason or another, but all 
> should be addressed during the design process.  I am definitely 
> interested in helping with the design of a prototype.  I have the 
> latest version of AutoCAD, as well as Visio--whatever the preferred 
> file type is.  I can always convert to PDF.
>
>  
>
> Also, I received my new mini-lathe last Friday, and plan on machining 
> a small nozzle here shortly.  I was reviewing the PDT testing 
> document, looking for items not yet assigned, and was thinking about 
> looking at the thrust characteristics for the various KNSB alloys.  It 
> would be awhile, however, until I manufacture a nozzle, test it, build 
> a test stand, make the alloys, etc... someone may well get to it 
> first.  Are there any pending items in the PDT test document that are 
> more immediately needed?
>
That'd be super. There certainly are items not yet assigned, see the 
following document:

http://sugarshot.org/downloads/pdt_investigations-assigned.pdf

>  
>
> Please forward to the propellant and/or main list (or I can), if any 
> of the above would generate useful discussion, and let me know what I 
> can do.
>
>  
>
> Thanks,
>
> Rich Hansen
>
> rhansen at mc2inc.net
>
Thanks again, Rich.

Richard
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