Those are all failures after the match is lit. Primary payload doesn't
care about that.
A solid sitting still with a mechanical dead short or 3 across it's
ignition leads is fairly inert compared to a custom made set of tanks,
pressure vessels and valves all full of interesting chemicals .
On 28/4/20 4:21 pm, ken mason wrote:
That is an interesting statement/claim and one of which I'm not disagreeing with but I'd like to bring up some interesting observations on the topic of solid rocket reliability keeping in mind I have no horse in this race and enjoy working with both solid and liquid systems my entire life.
In my aerospace career the following major rocket failures occurred related directly to a solid rocket motor.
Space Shuttle Challenger
Titan 34D, VAFB SRB failed ~T+15, loss of a 1 B$ DOD payload, possibly KH-11, 12 or Lacrosse.
Delta with SRB failure ~T+15, I forgot the date/mission but you all remember the shower of flaming solid propellant onto PRV's, Privately Owned Vehe's
IUS failed at orbital insertion, circa ~1986
I was involved in the investigations of #2&4, both occurred mid 80's while working at UTC/CSD San Jose,CA.
.Also generally speaking when a solid fails it's usually catastrophic while a liquid usually doesn't mean loss of mission/payload like POGO in a Saturn or the resent Space X engine out.
Yes, I know this will fire up a storm of opinions and I know some of the caveats, I just bring these cases up for discussion and thought among colleagues.
Ken
On Mon, Apr 27, 2020 at 10:32 PM Jake Anderson <dmarc-noreply@xxxxxxxxxxxxx <mailto:dmarc-noreply@xxxxxxxxxxxxx>> wrote:
For a cubesat if it's a secondary payload the primary payload may
feel happier about it from a "less to go wrong" POV.
That said having a primary be ok with anything more potent than a
decent spring would probably be an achievement in the first place.
On 28/4/20 2:58 pm, roxanna Mason wrote:
That the unknown, time. Can't test for it other than spending the
time to test a system. If 15 moths were an upper limit then a
liquid bi or mono prop is
still a good contender. Liquids worked at 100% reliability at
Pluto after a 10 year journey and beyond to some asteroids didn't
it or was it 100% gravity assist after initial boost?
Still, the fundamental question remains - Why solid over liquid?
On Mon, Apr 27, 2020 at 7:29 PM Henry Spencer
<hspencer@xxxxxxxxxxxxx <mailto:hspencer@xxxxxxxxxxxxx>> wrote:
On Mon, 27 Apr 2020, ken mason wrote:
> ...And does the solid propellant of the fired motor, which
has been
> exposed to the vacuum of space, not degrade?
Depends on what it's made of. There have been concerns about
this in the
past, leading to use of nozzle plugs, but also some
counterexamples, e.g.
Magellan's VOI motor spent 15 months in space without a
nozzle plug, and
worked fine when it was fired at Venus.
Henry
