Sorry you feel that way it's not my intention, maybe guilty of style but
not content.
On Tue, Apr 28, 2020 at 6:29 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Ken,
Please don’t say you’re not trying to turn this discussion into a heated
debate because that’s exactly what you were doing - read back your posts –
it’s not subtle!
Fortunately this list is wise enough to appreciate that with propulsion
systems (as with many other things), there are horses for courses. Some
things are suited to solids, some are suited to liquids and others are
suited to hybrids and other. For a long time now we’ve all moved on from
the narrow-minded “my favourite system is the only choice worth
considering” due to these (cherry picked) stats.
I think there’s general agreement here for quite some time now that
liquids are the only sensible option for manned launch vehicles. There’s
little to be gained by jumping up on a soap box here (repeatedly) and
preaching that. Maybe save your efforts for your local congressional
representative?
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *roxanna Mason
*Sent:* Wednesday, 29 April 2020 10:49 AM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Restart-able solid rocket motors for cubesats
No Bill, just talking about propulsion failures. Also the liquid core had
a leak to failure in another flight, but I'm not really trying to turn this
discussion into a heated debate just showing both systems are not perfect..
On another topic completely for early am tomorrow:
*Asteroid* 1998 OR2
<https://www.ucf.edu/news/asteroid-visiting-earths-neighborhood-brings-its-own-face-mask/>,
a 1.2 mile (2 kilometer)-wide space rock. And though the asteroid is on the
list of potentially hazardous objects (PHOs), the April 29th pass at
0.042 Astronomical Units (AU) from Earth at 9:56 Universal Time (UT)/5:56
AM Eastern Daylight Saving Time (EDT),
dawn your hardhats.
On Tue, Apr 28, 2020 at 5:42 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Ken:
Are you intentionally overlooking the three Titan 4’s lost due to other
failures?
Facts matter: One SRB failure in 78 flights vs. three other failures in 39
flights; one in 78 vs. one in 13. It is not SRB failures that drove
reliability in that vehicle.
Bill
On Tue, Apr 28, 2020 at 5:51 PM roxanna Mason <rocketmaster.ken@xxxxxxxxx>
wrote:
FYI, Another major solid failure on a Titan 4,:an SRM exploded at T+101s.
Non tit for tat but it seem liquids
are inordinately successful despite their complexity. I think as time
passes this discussion will fade as
Space X all liquids dominates the west and Russia the other side with
China the wild card pending the outcome of the new deal with US and the
virus.
On Tue, Apr 28, 2020 at 3:20 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Sigh.
As I have posted many times before, a careful analysis of all space
launches worldwide between 1980 and 2010 shows that liquid stages (of space
launch vehicles) fail twice as often as solid stages.
Even if we ignore all non-western launches, liquid stages still fail more
often, although not quite twice as much.
The reason for this difference appears to be complexity. An open
question—for which there is some statistical evidence—is whether reuse
improves reliability, a potential advantage that would tend to favor liquid
stages.
Bill
On Tue, Apr 28, 2020 at 4:03 PM roxanna Mason <rocketmaster.ken@xxxxxxxxx>
wrote:
On the liquid side of the equation let's throw in the liquid Centaur,
almost 100% except for that pesky purge failure where the turbopump iced up
preventing its start up. So a know failure mode led to a reliable fix a
hindsight issue of fixing something that worked just fine.
On Tue, Apr 28, 2020 at 2:51 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Tue, 28 Apr 2020, George Herbert wrote:
I would add the Titan III and IV solids to those numbers. Segmentation
is a good breakpoint.
Also the original H-II solids. JAXA switched to one-piece solids for the
H-IIA and H-IIB. Ironically, although the switch was partly meant to
improve reliability, I think the only big-solid failure they've had came
*after* the switch -- hot-gas leak caused a separation failure.
Henry
