D-12 on Initiator's Maiden Flight

D-12 on Initiator's Maiden Flight

Post by Dave Johnston http://www.telusplanet.net/public/davidrj/homepg.htm » Fri, 22 Aug 1997 04:00:00



I finally had a perfectly calm day to launch my Initiator on a D-12-3.
It was something I had to try just to see this large rocket barely get off
the pad, lumber into the air and eject just in time to fill the chute slow
down and land with very little drift time.
The small field that I have at home would be plenty big for a flight like
this.
I asked about doing this awhile ago on this 'ng' and said I would report
back if I did try.
Well, the question if this would be enough power for this rocket with a
short enough delay before ejection became moot when the baby Cato'd three
feet off the rod.
It lifted off very nicely, no doubt it was going to be a good flight up and
then 'BLAM', I wish my ignitor cable was extended to its' full 50+ feet.
The concusive force reminded me of my field artillery piece (an inch and a
half, smooth bore that burns 750 grains of single F blackpowder and pushes
two-thirds of a pound of lead to 600+ ft./sec.).
The explosion blew the nose cone off and pushed the Arrowtech baffle plug
half-out and blew the engine and adapter completely out the back. It was
such a hot blast it blistered the paint on the body tube about even with
the top of the motor tube. It burnt a thin layer (coating?) off the inside
of the body tube about halfway up, and the top of the motor tube was torn
and burnt (I suspect the glue held somewhat on the baffle plug, therefore
the tearing).
I will be able to rebuild it, but I haven't made up my mind on how to
proceed. I am thinking about somehow removing the motor tube and rebuilding
it stock, however at this point I could just as easily make some integral
changes. Getting the other two centering rings free could be a good trick,
so I am considering other options.
I like the idea of some kind of piston system. Should there be a vent in
the body tube at a point that the piston slides by allowing ejection gases
to escape and therefore not drive the piston right out?
Any such system probably would require a CG/CP check. I am sensitive to
this as I had a recent CP/CG mishap which I will outline in another post.
Anyway, any comments or suggestions are welcome.
--
Dave Johnston

d
rj
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