Ballistic Rocket Chute FS

RAM wrote:
"Gig 601XL Builder" wrDOTgiaconaATcox.net wrote in message
...

"RAM" wrote in message
news:wWV0g.930487$xm3.207853@attbi_s21...

It appears then that the rocket is the link in the "system" that is most
likely to degrade with time. Given a choice (and assuming I needed it),
I'd
rather have a system with a questionable rocket than none at all!!


There are other names for a questionable rocket. One that comes to mind is
bomb.



That's a valid point, although I've never heard of a solid fuel rocket in a
ballisticaly deployed parachute "exploding". I believe that it the event of
an instantaneous and total ignition of the charge (which you alude to) the
container would fail long before an explosive pressure could be generated.
I think the issue of rockets that are "old" is the previously mentioned
oxide which forms resulting in a misfire.


A cow-orker and his brother used to build and launch model rockets in
Williams Bay, Winsconsin. Two of them, using off-the-shelf solid
propellant motors blew up on the launch pad. Both incidents occurred
in the dead of Winter. He thinks the manufacturer of the solid motors
recommends against use below some critical temperature.

One supposes that the BRS makers have taken such effects into
consideration.

But it is not an unreasonable concern.

Besides, if you use the bang chute and it fails the particulars of the
failure mode are probably of little consequence. Don't most
manufacturers repack the chute and replace the rocket for a fee?

--

FF

The very early chutes were deployed with what amounts to a shotgun shell,
with a big rifled slug. I don't know how well that worked or didn't. They
must have had a reason to start using rockets.

Anyway, I have a whole box of WW2 vintage 30-06 ammunition that still works
fine. I find myself wondering if any of those first chutes are still
around...

wrote in message
ups.com...

...

A cow-orker and his brother used to build and launch model rockets in
Williams Bay, Winsconsin. Two of them, using off-the-shelf solid
propellant motors blew up on the launch pad. Both incidents occurred
in the dead of Winter. He thinks the manufacturer of the solid motors
recommends against use below some critical temperature.

One supposes that the BRS makers have taken such effects into
consideration.


That's a common failure mode for black powder rocket motors (e.g. Estes
motors). IIRC, the grain shrinks away from the case and you have too much
surface exposed which causes it to burn faster and generate more pressure
than the case can withstand.

If I were to guess, I would say that the rockets used in the balistic
'chutes is more likely an Ammonium Percloric (spelling? ain't got a clue)
based propellent with a rubber binder. They seem lest susceptable to this
particular problem.

You could ask over on rec.models.rockets...

--
Geoff
The Sea Hawk at Wow Way d0t Com
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When immigration is outlawed, only outlaws will immigrate.