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'[EE]: Rocket Science (Altimeter Project)'
2001\01\18@212629 by Barry Gershenfeld

picon face
>> BTW, why does cracked
>> propellent cause an explosion? It was a very violent explosion, too; did a
>> lot of damage to the base of my launch stand.
>
>        From how I understand those motors are constructed I do believe age
was the
>factor. The bottom of the engine is an epoxy based nozzle. If that nozzle
>cracks it will fly apart when the engine ignites. Since the whole
>contraption now has the whole diameter of the engine to flare out it burns
>much more violently.

I think you'd have less thrust and the gas can escape more easily.

What would really do it is if the propellant cracked and a piece of
it blocked the opening in the nozzle.  Then the pressure would
rise until something gave way (in other words you just created
a bomb).

Barry

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2001\01\18@234931 by Herbert Graf

flavicon
face
> >        From how I understand those motors are constructed I do
> believe age
> was the
> >factor. The bottom of the engine is an epoxy based nozzle. If that nozzle
> >cracks it will fly apart when the engine ignites. Since the whole
> >contraption now has the whole diameter of the engine to flare
> out it burns
> >much more violently.
>
> I think you'd have less thrust and the gas can escape more easily.
>
> What would really do it is if the propellant cracked and a piece of
> it blocked the opening in the nozzle.  Then the pressure would
> rise until something gave way (in other words you just created
> a bomb).

    Didn't think of that, that would make more sense! TTYL

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2001\01\19@004122 by David VanHorn

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face
>
> > I think you'd have less thrust and the gas can escape more easily.
> >
> > What would really do it is if the propellant cracked and a piece of
> > it blocked the opening in the nozzle.  Then the pressure would
> > rise until something gave way (in other words you just created
> > a bomb).


I have also seen occluded nozzles in the estes products. This would give
you low thrust, but I don't believe a longer burn duration. I think the
chamber pressure and temp goes up, hopefully it dosen't split the casing.

The aerotech system is SO much better! Graphite nozzles, O-Rings, Composite
propellant, which dosen't crack, because it's like a pencil eraser, gummy
not like a rock.

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