Newsgroups: sci.space.policy
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: MSFC engine
Organization: SP Systems, Toronto
Date: Mon, 25 Dec 1995 03:55:38 GMT

In article <m2n38jhxmf.fsf@harvey.cyclic.com> kingdon@harvey.cyclic.com (Jim Kingdon) writes:
>Microcosm specifically mentions operability--they do not require a
>launch tower (because their vehicle is wide and fat and has all its
>umbilicals connected at the bottom).

Actually, Proton doesn't use a tower either.  (Yes, it has plumbing up the
side of the lower stages for fuelling the upper stages.)  The towers used
at launch (as opposed to some of the ones used for preparations) do not
contribute significant mechanical strength to existing vehicles; they're
there solely to hold electrical connections, plumbing, and swarms of guys
with clipboards.

Quite a few of the new launch outfits have noticed that towers are of very
limited utility, especially if you consider the guys with clipboards to
be liabilities rather than assets.  Taurus doesn't use a tower, and I don't
think LLV does either.
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu

Newsgroups: sci.space.policy
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: towers (was Re: MSFC engine)
Date: Wed, 27 Dec 1995 00:51:29 GMT

In article <4bmjrg$v5k@usenetw1.news.prodigy.com> MMFF37A@prodigy.com (Michael Gallagher) writes:
>> ... Quite a few of the new launch outfits have noticed that towers are 
>>of very limited utility ... Taurus doesn't use a tower, and I don't
>>think LLV does either.
>
>Bad examples: both Taurus and LLV are solid fueled rockets, so neither 
>REQUIRES towers for fueling.

Uh, so?  Are you under the impression that towers are required for fueling
of liquid-fuel rockets?  Not so, not even if the rocket is multi-stage.
See my original posting.

>Furthermore, since Taurus is designed to be 
>launched from a site offering no more than a concrete slab, they errect a 
>temporary scaffolding as they assemble the rocket, and take it down 
>before launch...

I'm not sure what you're trying to say here.  I make a distinction --
which was mentioned in my original posting -- between fixtures used for
assembly and erection, and the classical umbilical tower which remains
in place until launch.
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu

Newsgroups: sci.space.policy
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: towers (was Re: MSFC engine)
Organization: SP Systems, Toronto
Date: Thu, 28 Dec 1995 22:01:53 GMT

In article <4bskrp$q5u@ddi2.digital.net> Edgar Zapata <edgar.zapata-1@kmail.ksc.nasa.gov> writes:
>>Are you under the impression that towers are required for fueling of 
>>liquid-fuel rockets?
>
>For a cryo fueled rocketsuch as Shuttle it should be noted that the 
>towers as needs could be classified as "access" (due to poor 
>supportability), "hazards" (no free hydrogen venting) and "lack of 
>robustness / more hazards" (no ice allowed; the tile is not robust enough 
>for ice debris, such as from a GOX vent at the top of a tank.)

There's a false dichotomy here:  no tower does not imply free venting.
Just run a vent line down the side, connecting to permanent vent plumbing
in the pad.

As for "access"...  Access for *what*?  If you put the vehicle together
and test it before rollout, you don't need elaborate access on the pad.
Look at Ariane 5, which has only a stumpy little umbilical mast on the
pad, or Proton, which doesn't even have that.  This works partly because
these vehicles are built around a philosophy of minimizing on-pad work.
(Ironically, this was also the basic philosophy for KSC.  The one time
NASA actually made a strenuous effort to do things that way -- for the
Skylab workshop -- it worked very well and saved quite a bit of money.)

>...Also, the vehicle skin would have to be 
>able to take blows.  An aircraft like structure would likely do...

Do note that Atlas and the Saturns used uninsulated LOX tanks, which grow
a layer of ice during fuelling and shed it at launch, with no particular 
difficulties in this area.  Agreed that you can't do it if you've got
something as fragile as the shuttle tiles exposed.
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu

Newsgroups: sci.space.policy
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: towers (was Re: MSFC engine)
Date: Fri, 29 Dec 1995 03:56:41 GMT

In article <4bu969$1cje@usenetw1.news.prodigy.com> MMFF37A@prodigy.com (Michael Gallagher) writes:
>>Uh, so?  Are you under the impression that towers are required for fueling
>>of liquid-fuel rockets? 
>
>That wasn't my point.  You were talking about fueling liquid-fueled 
>rockets without towers, and you used Taurus as an example of a booster 
>that doesn't have a tower.  MY point is you can'y use it as an example of 
>a tower-less liquid-fueled rocket because it isn't a liquid-fueled rocket 
>in the first place!  Ok?

I was talking about *launching* without towers.  You're the one who
decided that the discussion was specifically about fueling.

While solid-fuel rockets don't have to worry about getting fuel into the
upper stages, by the way, typically they *do* have to worry about arming
the igniters and other pyros in the upper stages.  This sort of thing is
one reason why NASA tends to insist on towers, but other people seem to
be able to do without somehow.

Incidentally, I did supply an example of a tower-less liquid-fuel rocket,
in fact a rather large one.  Name begins with "P"...
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu

Newsgroups: sci.space.policy
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: towers (was Re: MSFC engine)
Date: Sat, 30 Dec 1995 17:52:13 GMT

In article <4c2elf$r7p@vixen.cso.uiuc.edu> jbhopkin@ux4.cso.uiuc.edu (Joshua B Hopkins) writes:
>Proton has no launch tower, and neither does Zenit...
>Both of these are large, liquid fueled boosters.  It's pretty
>clear that towers are not a major requirement for anything but
>crew-launch vehicles, or biological sample which have to inserted in
>an experiment at the last minute. 

Even vehicles which do have on-pad access, like the shuttle, typically
want loading of things like biological samples to be complete several
hours before launch.  This could be handled without on-pad access, for the
most part, if you adopted a philosophy of "roll it out, fill it up, and
launch it".  Not even the Russian launchers go quite that far toward
minimizing on-pad time, though... at least, not with their normal
peacetime operational practices.

As for things carrying people...  It's interesting to note that Zenit was
meant to replace the "A" series boosters, meaning that it would have taken
over the manned launches among other things.  One wonders what would have
been done about crew access.
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu