Fat Boy - cluster

Fat Boy - cluster

Post by Robert F. N » Wed, 12 Sep 2001 11:12:40





Quote:

>>I didn't take quite as extreme a position.  I put in 2-18 mm mounts
>>one to pop the nose and one to eject the parachute.  I flied this one
>>for the first time Friday on a B6-4 and a B6-6.

>>Check it out at:

>>http:www.mich.com/~ywu/rock/rpix/fb1.jpg

>>and

>>http:www.mich.com/~ywu/rock/rpix/fb2.jpg

>That's a very unusual clustering set-up.  What's the logic for the two
>stage ejection.  (For those who haven't seen the pictures, one of the
>18mm engine tubes extends all the way into a cut-out in the nose cone,
>while the other one seems to terminate normally inside the main body
>tube.)

I would image that the B6-4 is used to pop the nose cone and
destablize the bird while the B6-6 pops the chute.  This allows
the rocket to deploy its chute lower to the ground to prevent
drift.  I would say this is rather clever.  I may try it myself.

To the original poster:  Did you have any stability problems with the
addition of the second motor considering the model's short length?

Robert F. Nee

 
 
 

Fat Boy - cluster

Post by Jim Z in V » Wed, 12 Sep 2001 12:13:22


Quote:

> >>I didn't take quite as extreme a position.  I put in 2-18 mm mounts
> >>one to pop the nose and one to eject the parachute.  I flied this one
> >>for the first time Friday on a B6-4 and a B6-6.

> >That's a very unusual clustering set-up.  What's the logic for the two
> >stage ejection.  (For those who haven't seen the pictures, one of the
> >18mm engine tubes extends all the way into a cut-out in the nose cone,
> >while the other one seems to terminate normally inside the main body
> >tube.)

Robert F. Nee wrote

Quote:
> I would image that the B6-4 is used to pop the nose cone and
> destabilize the bird while the B6-6 pops the chute.  This allows
> the rocket to deploy its chute lower to the ground to prevent
> drift.  I would say this is rather clever.  I may try it myself.

        I tried something very close to this a couple years ago in a
scratchbuilt design I called "Poor Man's Dual Deployment" (basically a Fat
Boy sized BT with a Phoenix-type NC and six fins). A 2 x 18mm cluster ejects
into two internal stuffer tubes (toilet paper tubes actually), one with a
small chute or streamer and the other with a big chute. It flies very well
to about 500' on a C6-3 / C6-7 combo or 850' on D21-4 / D21-7. The dual
deployment feature is fun (takes people by surprise) but the 3 or 4 second
difference in delays is not very effective in reducing drift.....it really
hasn't fallen very far before the 2nd chute deploys.
--
Jim

"If you can't beat 'em,
arrange to have them beaten."
                                         - George Carlin