Re: ERPS-list Digest, Vol 7 #7

Ian,

>However, compared to a similar construction TSTO I found my payload 
>dropped precipitously, by 75%.
>
>That's *really* bad.
>
>So I have to either build my launch vehicle 4x bigger or launch 4x more 
>often. IMO neither seems like a brilliant idea. I think the costs go up 
>by 4x, and then you have to claw it back by making your launch vehicle 
>more reusable... but adding reusability also costs payload... it's 
>rather a slippery slope.
>  
>
Actually, requiring a 4x higher flight rate is not necessarily a loss, 
so long as you have at least some
payload.  That just means 4x as many flights to amortize your vehicle 
over, getting more efficiencies
of scale, etc.

However, there are slightly better ways of doing this than the straight 
up and down first stage, but
I'm not a real fan of "flyback boosters".  They tend to really start 
forcing your design in a route
that I personally don't like.

~Jon