On Sun, 25 Aug 2002 09:11:03 -0700, The Silent Observer
<[EMAIL PROTECTED]> wrote:
>To disagree with Ian a bit, ISTM that Delta V is the factor that can be
>increased by actual engineering
That was my conclusion as well. It's also the best indicator of raw
performance.
>Assuming KISS II had a Delta V of around 400 m/s (subsonic plus gravity
>losses for that 6500' flight -- and it's a guesstimate), will KISS III
>be capable of 800 m/s?
KISS II was more like 200 m/sec. KISS III will be somewhat less,
initially: while the thrust will not tail off, the burn time will be
shorter, and the vehicle will be heavier.
It is theoretically possible that KISS III will have double the
performance of KISS II - if we fill the peroxide tank to 10 liters
instead of KISS II's 4 liters. This would add over 8 kg of liftoff
weight to a vehicle whose T/W is already alarmingly low. We'll try to
work up to a 10 liter fill, but if it's too risky, we won't chance the
vehicle or our scarce peroxide. RIMTIP: Reliability Is More Important
Than Performance. (Acronym rearranged in the interest of
articulability :-)
But let's assume for a moment that we can apply Moore's law, with a
coefficient of one year, to ERPS vehicles' delta-v.
2002 KISS I, II, III 200 m/sec
2003 Spike? 400 m/sec
2004 Spike B? 800 m/sec
2005 ReSOAR? 1600 m/sec
2006 ReSOAR 3200 m/sec
2007 PROTO 6400 m/sec
2008 PROTO 12,800 msec
Two things stand out here. One, I doubt we can work that fast, and
this *isn't* a projection, prediction, promise, or commitment, past
performance is no guarantee of future results, and use only in a well
ventilated area. Two, even if we double the coefficient in deference
to our amateur status, these numbers take us from small sounding
rockets to nearly escape velocity in six years. That's not realistic.
Getting to serious suborbital flight is "just" engineering, but as we
get near the magic 10 km/sec, life is going to get a lot harder, and
performance numbers will threaten to plateau short of that goal.
(That's when we start looking seriously at Dan's scary ideas.)
Another thing occurs to me. If one or two ERPS members could devote
themselves to ERPS full time, going from KISS III in 2002 to Spike B
(B for biprop) in 2004 would probably be achievable. I won't hold my
breath.
-R
--
"Sutton is the beginning of wisdom -
but only the beginning."
-- Jeff Greason
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