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From: (Henry Spencer)
Subject: Re: Atlas IIAR = Titan = EELV
Date: Tue, 21 Nov 1995 23:14:37 GMT
Organization: U of Toronto Zoology
Lines: 70

In article <48fg79$> John Pike <> writes:
>>Fighter         F-4         F-15        F-117         F-22
>                 F-4         F-15        F-15          F-15
>The "F"-117 is not a "fighter" but rather it is a light bomber, and the 
>F-22 is a future system...

Actually, the F-16 got missed somewhere in there -- in most ways it is
a rather better fighter than the F-15, and it was a somewhat later

> Space launch   Delta C     Delta 2910   Delta 3920    Delta II
>                Atlas LV3   Atlas SLV3C  Atlas G       Atlas II
>                Titan 2     Titan 3      Titan 34D     Titan 4
>Although the names have been kept the same to protect the guilty, the 
>current launch vehicles have only a vague family resemblance to their 
>progenitors of three decades ago [am I really that old???].

The family resemblance is a bit closer than that, I'd say.  The engines
are almost the same, with minor upgrades and tweaks.  The tanks have
gotten longer, in some cases (Titan IV) enough to impose serious
structural limitations.  The electronics boxes are better, although often
just modest improvements layered on top of the old stuff rather than full
rethinking (I'm told that an inspection of the Titan 34D guidance software
found three slightly-different values for Earth's radius).  These aren't
even new members of the family, just the same ones, now with middle-age
spread and thinning hair instead of bubblegum and sneakers. 

>But, another take: compare and contrast the boundless creativity of 
>nuclear weapons designers during the 1950s versus the past decade or two. 
>We are now on the verge of a Comprehensive Test Ban due in no small 
>measure to the exhaustion of technological possibilities...

You can find people who will say that this was much more a matter of
political restraints than of technological limitations.  An unclassified
analogy is that the US almost certainly ended exploration of the design
spaces for both fission reactors and fusion reactors too early, not
because people ran out of ideas but because decision-makers ran out of
patience.  For example, none of the major US fission-reactor designs can
be refuelled while in operation, yet this is not terribly hard to do (the
Canadian heavy-water reactors, whose basic design dates to about the same
time, do it) and it is a major advantage for an operational power plant.
For another example, the molten-salt reactor had a number of practical
advantages over existing designs, but never got beyond small testbeds.
The extent to which analogous situations might exist in bomb design is
hard to assess without a suitable security clearance (and hard to talk
about with one!).

I think one can make a good argument that, starting in perhaps the late
1950s, there began to be a perception that stability was desirable and 
that restraining technological innovation in bomb design might be a good 
idea, regardless of the potential technical merits of further advances.
It is very hard to evaluate the technological maturity of a field from
the outside when political considerations might have had the same effect
as exhaustion of technical possibilities.

As for the application to spaceflight, I think it is sufficient to note
that people were building workable ion engines in the 1960s, but they are
only now starting to be used in *some* of the applications which have been
crying out for higher Isp for two decades.  If you want an example more
relevant to launchers, consider that McDD rejected the aerospike engine
for the DC-Y design partly because nobody had ever flown one and hence
there were lingering unknowns about aerodynamic interactions at low
supersonic speeds.  (Wind tunnels?  Wind-tunnel tests said that the DC-X
landing was going to be very tricky, highly unstable, working the control
system to its limits... while in fact it was utterly benign.)  The idea
that this field reached technological perfection in the 1960s is absurd.
The problem is, every time something goes wrong,   |       Henry Spencer
the paperwork is found in order... -Walker on NASA |

From: (Henry Spencer)
Subject: Re: New Book on Challenger (WasRe: Challenger Report)
Date: Sun, 10 Dec 1995 22:20:22 GMT
Organization: U of Toronto Zoology
Lines: 22

In article <> (Thomas J. Frieling) writes:
>>>The author sees Challenger type accidents as inevitible as technology grows 
>>>ever more complex and the ability of mere humans to control...
>>This is silly.  Challenger-type accidents would occur even if technological
>>advance was completely frozen. 
>Isn't your logic a bit circular here?

The wording may have been poor, but the logic isn't. :-)  The problem is
not with ever-more-complex technology becoming less controllable, but with
mismanagement interfering with control of technology that is, if anything,
becoming *more* controllable.  Control diminishes as you go into the past,
not the future.

Those who argue otherwise are so preoccupied with the hazards of new
technology that they ignore the hazards of old technology.  To take a
particularly loaded example :-), the death rate among coal miners, per
kilowatt-hour of electrical energy produced, is far worse than anything
which would be considered tolerable in the nuclear-power industry. 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |

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