BAR: Single stage engines in upper stage?

BAR: Single stage engines in upper stage?

Post by Helen Rapoz » Tue, 08 Oct 1996 04:00:00




Quote:
> Q:In a pinch, can I use a single stage engine in the upper stage of a two
> stage rocket? (Estes engines.)

> I'm selecting engines for our upcoming Cub Scout Rocket Launch.
> We have some boosters left over from last time, but no uppers.
> If possible. I'd like to use A8-3s on top of B6-0s. This way, I
> won't have to buy A8-5s. I know I could use the A8-5s in a single
> stage model, but they're only recommended for light models,
> which we won't have.  (Scouts tend to build on the heavy side.)
> Only a couple of kids have 2 stage
> rockets, so I don't want to buy A8-5s for everyone, especially
> if none of the 2 stagers shows up.

************
Depends on the rocket.  If it was a Warp II (or Loadstar) and
it had carried a 1/2 to 1 ounce payload then yeah, using a
A8-3 engine would be wise.

If it's a Mongoose, maybe not unless you load it with some
baby powder.

 Honolulu Community College         _^_     Twas the second month of
 874 Dillingham Blvd.              /   \    fall.  TV shows are airing
 Honolulu, HI 96817                |   |    new episodes, parks are not
 Ph#:  (808) 845-9202              |   |    that crowded on the weekends
 FAX#: (808) 845-9173              |   |    and I can't think of anything


 
 
 

BAR: Single stage engines in upper stage?

Post by Bill Michae » Wed, 09 Oct 1996 04:00:00


Q:In a pinch, can I use a single stage engine in the upper stage of a two
stage rocket? (Estes engines.)

I'm selecting engines for our upcoming Cub Scout Rocket Launch.
We have some boosters left over from last time, but no uppers.
If possible. I'd like to use A8-3s on top of B6-0s. This way, I
won't have to buy A8-5s. I know I could use the A8-5s in a single
stage model, but they're only recommended for light models,
which we won't have.  (Scouts tend to build on the heavy side.)
Only a couple of kids have 2 stage
rockets, so I don't want to buy A8-5s for everyone, especially
if none of the 2 stagers shows up.

TIA!

 
 
 

BAR: Single stage engines in upper stage?

Post by The Silent Observe » Wed, 09 Oct 1996 04:00:00


Quote:

> Q:In a pinch, can I use a single stage engine in the upper stage of a two
> stage rocket? (Estes engines.)

Well, yes, but...

Quote:
> I'm selecting engines for our upcoming Cub Scout Rocket Launch.
> We have some boosters left over from last time, but no uppers.
> If possible. I'd like to use A8-3s on top of B6-0s. This way, I
> won't have to buy A8-5s. I know I could use the A8-5s in a single
> stage model, but they're only recommended for light models,
> which we won't have.  (Scouts tend to build on the heavy side.)
> Only a couple of kids have 2 stage
> rockets, so I don't want to buy A8-5s for everyone, especially
> if none of the 2 stagers shows up.

With the motors you specify, unless the rockets are either heavy or
draggy, or both, the A8-3 will eject well before apogee, with the rocket
still rising a considerable velocity.  The A8-5 would be perfect -- if
you can find any.  They've been discontinued by Estes, who apparently
decided no one would want to fly a minimum-diameter altitude type model
on an A (and recover it instead of losing it on a B), and only wimps
would put an A motor in the upper of an 18mm model.

You may be able to get away with A3-4Ts tighly friction fitted into
expended 18mm casings (knock out the nozzles of the casings with a
hammer first); the slightly longer delay and lower thrust would be pretty
close to right for an average 2-stage, like the Mongoose.  You might even
want to try using 1/2A3-4T motors the same way -- these would have almost
perfect delays for this use, and both mini motors are cheaper than the
A8-3s and A8-5s.

--
+----------------------------------------------------------------------+
| It's easier to create chaos than order -- 2nd law of thermodynamics  |
+----------------------------------------------------------------------+

| TableTop Publications http://members.aol.com/silntobsvr/ttop_pub.htm |
+----------------------------------------------------------------------+
| All opinions expressed are my own, and should in no way be mistaken  |
| for those of anyone but a rabid libertarian.                         |
+----------------------------------------------------------------------+

 
 
 

BAR: Single stage engines in upper stage?

Post by RichFre » Wed, 09 Oct 1996 04:00:00


You didn't mention what kind of rocket you were trying to stage.  The
shorter delay upper stage engine will work, but probably will eject before
apogee on most rockets.  However, if the rockets are heavy, they should
work fine.

BTW, as I understand it, Estes has discontinued the A8-5 engine, so if you
see them somewhere, buy them.  They won't be available for long.

PSC #473 Newsletter Editor
*** Freed, NAR 24586

Live long and perspire!  \\//_

 
 
 

BAR: Single stage engines in upper stage?

Post by Adrian Hu » Fri, 11 Oct 1996 04:00:00


Quote:

>Q:In a pinch, can I use a single stage engine in the upper stage of a two
>stage rocket? (Estes engines.)

>I'm selecting engines for our upcoming Cub Scout Rocket Launch.
>We have some boosters left over from last time, but no uppers.
>If possible. I'd like to use A8-3s on top of B6-0s. This way, I
>won't have to buy A8-5s.

I've used exactly that combination in my Estes Hercules.  (I didn't
want it going far; I just wanted to see the thing fly with two stages.)

One thing to bear in mind is that if the rocket is supposed to have finished
its climb 5 seconds after end of thrust, then it will still be going up at a
fair speed 3 seconds after thrust.  That means if you put in an A8-3, the
ejection charge will fire while the rocket is still going fast, which will
put a lot of strain on the parachute.  I got around this by fitting my
Hercules with a streamer instead of a parachute.

--
 "Keyboard?  How quaint!" - M. Scott