Newsgroups: sci.space.policy
Subject: Re: Atlas Re: Advantages of Hydrogen vs. Hydrocarbons (for SSTOs)
From: gchudson@aol.com (GCHudson)
Date: 11 Feb 1997 21:24:15 GMT

>No pressure, no Atlas.  I believe we're talking 0.030 aluminum here.

A nit: 0.012-0.040 full hard 301 stainless steel.

Newsgroups: sci.space.policy,sci.space.history
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: early SSTOs (was Re: Zubrin on TV)
Date: Fri, 14 Feb 1997 03:13:08 GMT

In article <5dsv8d$1tf@dfw-ixnews4.ix.netcom.com>,
Scott Lowther <lexcorp@ix.netcom.com> wrote:
>...One interesting note: The structure of
>the HATV (essentially a stainless steel ballon supported by internal
>pressure) was to find expression in the hydrocarbon fueled Atlas...

Actually, the idea wasn't new with HATV.  I believe it goes back to Oberth
at least.  By the way, a vehicle designed as an orbital launcher would
probably use aluminum rather than stainless steel -- Atlas used stainless
because of thermal problems in some "depressed" ICBM trajectories.
--
Committees do harm merely by existing.             |       Henry Spencer
                           -- Freeman Dyson        |   henry@zoo.toronto.edu

Newsgroups: sci.space.policy,sci.space.history
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: Interesting articles in AIR & SPACE
Date: Thu, 30 Jan 1997 15:16:35 GMT

In article <5co2ug$5j4$6@cronkite.seas.gwu.edu>,
Dwayne Allen Day <wayneday@gwis2.circ.gwu.edu> wrote:
>: Arnold got his way, and in 1947 started funding the MX-774
>: and by 1957, the atlas missile was standing...
>
>Fast-paced innovative engineering requiring a special projects office and
>a total suspension of traditional Air Force contracting.

One interesting consequence of this, as Robert F. Coulam pointed out in
"Illusions of Choice", is that everybody learned the wrong lessons from
the Atlas effort.

What they learned was that it was possible to do concurrent development at
a fast pace and have everything fit together and pretty much work.

What they didn't learn was that to make this technique *work*, you need
streamlined management, plenty of spare cash, and a firm determination to
maintain multiple parallel suppliers for anything important until major
uncertainties are resolved by prototype testing.

Atlas management never, ever, took it for granted that just because an
interface document said that parts X and Y would fit together, they
actually would.  If there was any serious concern about the matter, there
would be two suppliers funded to develop part X, and often two for part Y,
and the winners didn't get picked until hardware was available and actual
testing established that part X1 fit part Y2.
--
"We don't care.  We don't have to.  You'll buy     |       Henry Spencer
whatever we ship, so why bother?  We're Microsoft."|   henry@zoo.toronto.edu

From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: One and a half stage boosters?
Date: Fri, 10 Jul 1998 04:36:36 GMT

In article <1998071001351400.VAA03446@ladder01.news.aol.com>,
MattWriter <mattwriter@aol.com> wrote:
>I'm curious how the 1 1/2 stage Atlas series works.  Are the booster engines
>complete engines, or just nozzles?  And do they drop off after booster engine
>cutoff?

They're complete engines.  (Beware, there is confused terminology here,
since some odd people think that an "engine" is defined by pumps, not a
combustion chamber, so that a cluster of engines sharing a set of pumps
would be counted as a single engine.  That approach gets terribly messy
for the Atlas booster engines, since in some versions they shared pumps
and in some they didn't.)  Immediately after booster-engine cutoff, the
outer structural ring of the engine compartment, including the two booster
engines, is jettisoned.  This is the moral equivalent of dropping an
entire stage, since the Atlas tanks are so light.

>Same question for the Russian boosters - the R-7 and its decendants.  Are the
>"side boosters" complete engines, and do they drop off from the core vehicle,
>or was the R-7 first stage just a weird-looking 20-engine cluster?

The R-7 is better thought of as a two-stage system with parallel burn.
The "side boosters" are complete rocket stages, with their own tanks,
pumps, and engines, and they are jettisoned partway up.  It happens that
the core is lit at the same time they are, instead of waiting until near
separation time.  (This is not invariably the case for such systems; the
Titan IV core is *not* lit at liftoff.)
--
Being the last man on the Moon is a |  Henry Spencer   henry@spsystems.net
very dubious honor. -- Gene Cernan  |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.tech
From: henry@spsystems.net (Henry Spencer)
Subject: common engines (was Re: Could Sounding Rockets...)
Date: Wed, 9 Aug 2000 20:40:07 GMT

In article <39910A5F.FA2E2DF@mail.com>, Bill Bonde  <stderr@mail.com> wrote:
>> I'm obviously trading elegance, and ultimate performance, for ease
>> of manufacture, and simplicity.
>>
>I've always wondered if there was some way to use the same engines for
>two of the stages. The engines would be mounted a top the first stage
>and below the second...

Unfortunately, it wouldn't save much.  Much of the mass of a stage is the
engines.  This is illustrated by the original Atlas, which took things to
the opposite extreme:  a two-stage rocket with common tanks, where the
first stage was just a pair of engines.  (Well, there were a few other
things jettisoned along with the engines; for example, the pressurization
system went with them, with the tanks functioning as a blowdown system
for the remainder of the sustainer-engine burn.)

Atlas was admittedly an extreme design with very lightweight tanks, but
the bottom line doesn't change much with more conventional structures.
Boeing designed a very respectable launcher using an S-IC (first stage of
the Saturn V) that jettisoned its outer four engines partway up.  No extra
upper stage was needed to get 25t or so into LEO.

The shuttle may appear to be a counterexample, but note that it takes its
drop tank almost all the way into orbit.  The (supposed) benefits of that
approach show up mostly in reentry and reusability, not in ascent.
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)