A question on liquid propellant as it relates to stage size and fuel weight. . .

In article ,
Jonathan Silverlight wrote:
(More recently, during MOST planning we got the same message -- although
in relation to satellites rather than launchers -- from some of the Amsat
folks: forget about faking up hardware simulations of stuff that isn't
ready yet, unless it takes almost no effort; concentrate on getting the
first iteration of the real hardware running ASAP.) ...

I have a horrid feeling that European designers haven't learned either
lesson. I gather that Beagle 2 went through some drastic redesigns
before the final version emerged...

In itself, this is not inherently bad...

and as for putting valuable payloads
on the very first one, Cluster comes to mind.

Arianespace gets a lot of criticism for that, which I think is only partly
justified. Cluster got a large price break for taking a chance on the
first launch, and indeed the Cluster program could not afford to pay full
price for an Ariane 5 -- it was *designed* around the opportunity for a
cut-price risk-sharing launch. (And yes, this had design implications,
most notably the fact that the satellites needed extra maneuvering
capability, because they were to be dropped off in an orbit that suited
the launcher test rather than the Cluster mission.) Note that when
Cluster 2 rose from the ashes (or the swamps :-)), it did not fly on an
Ariane 5, but rather used a lower-cost launch option that wasn't available
at the time when the original mission was put together.

On the other hand, I do think Arianespace deserves part of the blame for
that mess, because they were far too optimistic about reliability. Had
they been honest and realistic, Cluster might not have flown with them.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |