Dholmes wrote:
"Ian Woollard" wrote in message
...

If this is so, it's still a win to make the vehicle smaller and simply
launch more; since that's a 15% decrease in costs per doubling. However,
I'm not as convinced that this 5-10% decrease is real. Do you have a
reference to this scaling law?

No just comparing rockets a different sizes but it appear consistent and
logical.

As I understand it, apart from minimum gauge and atmospheric drag,
there's no definite reason why larger rockets should be cheaper per kg.

However, there is likely to be an *apparent* decrease in cost with large
rockets as they are invariably scaled up version of previous rockets.
It's institutional learning, simply because it was version B; the
organisation has learnt how to build rockets better. For example, that
seems to be the case with Ariane V.

There where actual design studies to create a module for the cargo bay that
would have carried 75 people.

Yes, but what happens if it crashes? It's bad enough when Columbia or
Challenger crashed. If just one person dies, it's sad, but you don't get
the great upswelling to anything like the same degree. 75 people is a
different ballpark entirely.

75 people just isn't practical with the Shuttle; it's just not reliable
enough; and by the time it could have launched enough to be made
reliable, there would be several hundred dead.

With a single person, you can have an escape tower. With 75, there's no
chance of survival if there is a failure just after takeoff. People are
much less concerned about single deaths, although it would be newsworthy.

The market just is not there to support it.

Only Soyuz have seriously tried, and they have found that there is a market.

Interestingly a 6 man OSP would weight about 20 tons and require a heavy
lift vehicle so it would really use three rockets.
Half the number your 1 man plan uses. So even that increases volume of
rockets just not launches.

The OSP itself would be almost twice as expensive per person though.

By way of contrast the cost of developing a small vehicle is
proportionately lower, and you launch it much more often, so the
amortised cost of the development is far lower. Consider that the far
bigger Shuttle costs have never significantly amortised away; because it
has not, and could not be, launched enough.