Certification Project
Tripoli Level 3 for Mike Brest TRA #9383
Dynacom SAAB RB-05A (˝-scale)
TAP advisors: Tom Rouse, Ken Biba
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The Process Begins…The Motor Mount My first
issue to work out is the 4” motor mount, which is too big for the 98mm
Aerotech motor. A 4” motor mount is great
in the long run, because I’d like to fly some EX motors with this rocket if
it survives the L3 Cert flight. But
the size difference between a 98mm and a 4” has to be worked out. The difference in size shown clearly when
I wedge nearly the whole thickness of a pencil between a 98mm motor case and
the motor mount. This creates a
situation where the motor’s aft closure can easily slide right on into the
motor mount tube. The fix for this is
simple, I just happened to have a length of 4” paper tube that I used for an
adaptor (after peeling the surface layer of paper.) |
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These pictures left & right, give various perspectives on
the bad fit of the 4” motor mount using the 98mm Aerotech 10240 Ns case. |
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Motor Retention… The kit
provided aluminum motor retainer just barely stops the aft closure of the 98mm
motor from running right up through the rocket. And it does nothing to enhance the strength and tolerance for
impact of the aft end of the rocket.
To address this, I designed a new tail-cone / motor retainer
ring. I had two generous offers to
help from fellow rocketeers to do the lathe work making the retainer
ring. Tony Alcocer, and my primary
TAP Tom Rouse both offered their services.
Tom is a bit more of a drive and is already contributing significantly
by serving as my TAP Advisor, so I took Tony up on his offer. |
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On the
left, the design I gave to Tony. On the right is the part Tony built for
me. It’s going to look nice! |
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Left, is
the retainer installed in the rocket (both unfinished). Tony fine tuned the fit & anodized
the part once the rocket was near complete (right). |
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