Positive Motor Retention For a lOC Vulcanite

Positive Motor Retention For a lOC Vulcanite

Post by Mark Simpso » Thu, 04 Jul 2002 03:05:34



I've been working on several rockets that I've never flown, for various
reasons, in anticipation of flying them at NYPOWER2002.  One of those
rockets was a LOC Vulcanite H76.  I built it mostly stock (years ago, I
still followed directions) with the exception of using the, then touted,
anti-zipper technique.  What a mistake that was. I lost over 2' of
usable space doing that...but I digress.
The rocket has no positive motor retention. At the time that I built it,
I wasn't as gung-ho on it as I am now, but now I wanted to add positive
retention.  Looking at my options, T-nuts were out; not enough room in
between the 38 mm motor tube and 2" body tube.  Being a sensible person,
I can't see paying $30 for "slimline" motor retention on a rocket that
didn't cost much more than that when I bought it, so that was out.
I got a bright idea of using 3' sections of allthread and running them
the full length of the body tube from anti-zipper to past the rear
centering ring. No go. Besides the fact that the allthread rods were a
few inches short, I failed to remember that I'd also have to go through
the centering ring at the front of the motor; a ring that would be
difficult to drill holes in.
So, I was standing there holding my 3' section of 10-24 while sweat
rolled off my nose when it came to me.  Put a hook in the end of a piece
of the allthread rod and feed it into the centering ring.  As you
tighten it, the hook part grabs the inside of the centering ring and
voila!, positive retention.
Now, I'm sure that I wasn't the first to use that technique, but I had
to share my epiphany with all of you while I enjoyed a little air
conditioning in between trips to the very hot garage.

Mark Simpson
NAR 71503 Level II

 
 
 

Positive Motor Retention For a lOC Vulcanite

Post by BJames » Thu, 04 Jul 2002 13:49:36


Quote:
> T-nuts were out; not enough room in
>between the 38 mm motor tube and 2" body tube.

I built mine with T-nuts.  I just ground down the flanges of the T-nuts to
clear the motor mount and the main airframe.  I used 10-24 but later realized
that 8-32 would probably be just as good.

 
 
 

Positive Motor Retention For a lOC Vulcanite

Post by LOC PRECISIO » Fri, 05 Jul 2002 05:20:55


I did the same thing- careful not to burn your fingertips when grinding....
experience.
May also want to checkout the Slimline type retainer system.
barry

Quote:
> > T-nuts were out; not enough room in
> >between the 38 mm motor tube and 2" body tube.

> I built mine with T-nuts.  I just ground down the flanges of the T-nuts to
> clear the motor mount and the main airframe.  I used 10-24 but later
realized
> that 8-32 would probably be just as good.

 
 
 

Positive Motor Retention For a lOC Vulcanite

Post by Bob Kapl » Fri, 05 Jul 2002 09:30:12


Quote:

> So, I was standing there holding my 3' section of 10-24 while sweat
> rolled off my nose when it came to me.  Put a hook in the end of a piece
> of the allthread rod and feed it into the centering ring.  As you
> tighten it, the hook part grabs the inside of the centering ring and
> voila!, positive retention.

Does tha threaded rod stick out past the end of the MMT. The whole idea of
using my Klip design is you don't have sharp pointy things sticking out the
bootom of the rocket, where they can scratch a car or tear a tent even on a
gentle landing.

        Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"

Kaplow Klips & Baffle:      http://www.FoundCollection.com/
NIRA:   http://www.FoundCollection.com/    NAR:    http://www.FoundCollection.com/

        "I tell you, freedom and human rights in America are doomed.
        The U.S. government will lead the American people in and the
        West in general into an unbearable hell and a *** life."

        26-October, 2001: A day that will live in infamy
        Support Freedom: http://www.FoundCollection.com/

 
 
 

Positive Motor Retention For a lOC Vulcanite

Post by Bob Kapl » Fri, 05 Jul 2002 09:30:52


Quote:

>> T-nuts were out; not enough room in
>>between the 38 mm motor tube and 2" body tube.

> I built mine with T-nuts.  I just ground down the flanges of the T-nuts to
> clear the motor mount and the main airframe.  I used 10-24 but later realized
> that 8-32 would probably be just as good.

That's what I did on mine, but for retrofit like Mark needs, you could use
threaded brass inserts.

        Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"

Kaplow Klips & Baffle:      http://www.FoundCollection.com/
NIRA:   http://www.FoundCollection.com/    NAR:    http://www.FoundCollection.com/

        "I tell you, freedom and human rights in America are doomed.
        The U.S. government will lead the American people in and the
        West in general into an unbearable hell and a *** life."

        26-October, 2001: A day that will live in infamy
        Support Freedom: http://www.FoundCollection.com/

 
 
 

Positive Motor Retention For a lOC Vulcanite

Post by Mark Simpso » Fri, 05 Jul 2002 09:50:21


Not enough room for threaded inserts. I thought of that first.

Mark Simpson
NAR 71503 Level II

Quote:


> >> T-nuts were out; not enough room in
> >>between the 38 mm motor tube and 2" body tube.

> > I built mine with T-nuts.  I just ground down the flanges of the T-nuts to
> > clear the motor mount and the main airframe.  I used 10-24 but later realized
> > that 8-32 would probably be just as good.

> That's what I did on mine, but for retrofit like Mark needs, you could use
> threaded brass inserts.

>         Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"

> Kaplow Klips & Baffle:  http://www.FoundCollection.com/
> NIRA:   http://www.FoundCollection.com/    NAR:    http://www.FoundCollection.com/

>         "I tell you, freedom and human rights in America are doomed.
>         The U.S. government will lead the American people in and the
>         West in general into an unbearable hell and a *** life."

>         26-October, 2001: A day that will live in infamy
>         Support Freedom: http://www.FoundCollection.com/

 
 
 

Positive Motor Retention For a lOC Vulcanite

Post by Mark Simpso » Fri, 05 Jul 2002 09:51:22


Unfortunately, yes.  It was a retro-fit. I don't usually like things
*** past the motor, either.

Mark Simpson
NAR 71503 Level II

Quote:


> > So, I was standing there holding my 3' section of 10-24 while sweat
> > rolled off my nose when it came to me.  Put a hook in the end of a piece
> > of the allthread rod and feed it into the centering ring.  As you
> > tighten it, the hook part grabs the inside of the centering ring and
> > voila!, positive retention.

> Does tha threaded rod stick out past the end of the MMT. The whole idea of
> using my Klip design is you don't have sharp pointy things sticking out the
> bootom of the rocket, where they can scratch a car or tear a tent even on a
> gentle landing.

>         Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"

> Kaplow Klips & Baffle:  http://www.FoundCollection.com/
> NIRA:   http://www.FoundCollection.com/    NAR:    http://www.FoundCollection.com/

>         "I tell you, freedom and human rights in America are doomed.
>         The U.S. government will lead the American people in and the
>         West in general into an unbearable hell and a *** life."

>         26-October, 2001: A day that will live in infamy
>         Support Freedom: http://www.FoundCollection.com/