Re: Multiple Engines???

Heinrich Zinndorf-Linker ([EMAIL PROTECTED]) <[EMAIL PROTECTED]> wrote:
>Am 24 Nov 2003 10:43:17 -0800 schrieb "George William Herbert":
>>>I know of occurences, where the term 'hard start' WAS used as an
>>>euphemism to explain, why a mission goal could not be achieved. 
>>>
>>>One example I can pick out is the Ariane-5 mission (L#142) that should
>>>have launched Artemis and BSAT-2B to GTO - BSAT was lost completely,
>>>and Artemis lost much mission time by that so called hard start...
>>
>>So, find a second such incident.
>
>ok, look back to the development history of the first American liquid
>fueled multi-stage sounding rockets somewhen in the 19'fifties - there
>was that very same euphemism chosen for describing a failure cause. Or
>read the history of X-planes - you will find that term used in this
>way, too.

This is not an argument about whether Hard Starts ever happen.
They clearly have happened, a lot in engine development, and some
in early flight programs.  I was never challenging that.

I am challenging that Hard Starts are in any way a significant
contributor to production space launch vehicle launch failure
rates.

>But btw: I would not need to find more incidents than one - even one
>single documented use of that term (you're free to chose one :-)
>proves my words right, undeniable and without doubt.

Umm, no.  What you said earlier was:
Heinrich Zinndorf-Linker  <[EMAIL PROTECTED]> wrote:
>Am 22 Nov 2003 19:21:55 -0800 schrieb "George William Herbert":
>>>>Engines actually rarely explode on failure; going back
>>>>through the history of flight failures shows almost exclusively
>>>>systems failure followed by shutdown, or accidental shutdown,
>>>>without any uncontained failure.  It's not unknown but is a lot
>>>>rarer than 'graceful' shutdowns.
>>>
>>>Ok, then search for "hard start" instead - that's the euphemism used
>>>for engine explosion when it occurs on ignition. You will maybe
>>>surprised to find a significant number of them...

You specifically argued here that not just did hard starts
happen in production flights, but that there were a significant
number of them.

"one" is not "a significant number".

As I said; take the Space Launch Systems guide, 3rd edition,
and detailed failure histories of the various rockets,
and look at the failure causes.

Your assertion that there are a significant number
of them is not born out by the data, based on my
qualitative analysis when you first brought this up.

You are welcome to, for example, take all the failures listed
and categorize them and provide statistics, if you want to
argue the contrary.  But as I said... I didn't find any hard
start induced launch failures through 1999 in the book,
leafing through it to see what the historical occurrances
looked like.  I missed one or two somewhere?  Credible.
I missed something statistically significant, out of the
hundred or so entries for failures?  Less credible.


-george william herbert
[EMAIL PROTECTED]