Version of the Atlas II with no sustainer?

In article ,
Pat Flannery wrote:
http://www.geocities.com/atlas_missi...r_missions.htm
Is that supposed to be a four-engined variant of the Centaur on the
Atlas Cargo Vehicle? Or has somebody started clustering Agena motors?

The first Centaur concept had four engines. Engine size and number varied
somewhat during the early design work.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
Damon Hill wrote:
Atlas originally used steerable verniers and Atlas II replaced them with
roll thrusters (hydrazine monoprop?).

Hydrazine monoprop; the little bump on the interstage ring is the thruster
package.

One basic design principle of the original Atlas was that all, repeat all,
engines were firing before liftoff and were not shut down until they were
no longer required. High-altitude rocket-engine startup scared people
then. Hence the continuously-firing verniers, and also the unorthodox
staging concept. But the verniers were heavy, and their Isp wasn't as
good as the main engines.

When Centaur became a standard fixture on top, there was no longer any
need to use the verniers for velocity trim -- Atlas proper always drained
its tanks dry. The remaining role of the verniers, roll control after
booster-engine staging, required so little thrust and total impulse that
quite a small self-contained thruster package could do it. So when the
Atlas guys got some company-internal funding to cut costs and improve
performance, as part of the post-Challenger commercialization of
expendable launcher operations, that was one of the things changed.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Henry Spencer wrote:

The first Centaur concept had four engines. Engine size and number varied
somewhat during the early design work.


It would have been interesting to see what sort of payload weight a
manned derivative of such a combination could have delivered to
orbit...maybe Atlas/Centaur could have become our equivalent of the
Soviet Soyuz booster- our "get crew or cargo to a space station"
delivery vehicle using a evolved Gemini-based spacecraft....the path not
taken... :-\

Pat

Henry Spencer wrote:

One basic design principle of the original Atlas was that all, repeat all,
engines were firing before liftoff and were not shut down until they were
no longer required. High-altitude rocket-engine startup scared people
then. Hence the continuously-firing verniers, and also the unorthodox
staging concept. But the verniers were heavy, and their Isp wasn't as
good as the main engines.


The Soviets used the same "fire all motors on launch" concept on the R-7
(SS-6 "Sapwood") ICBM. I was always fascinated by their use of
interstage girders to allow the second stages of their rockets to ignite
before the first stage had finished firing; thus avoiding the use of
ullage motors to seat the second stage's propellants.
I am pretty sure we used the same technique on the Titan II ICBM.

Pat

In article ,
Pat Flannery writes:


Henry Spencer wrote:

One basic design principle of the original Atlas was that all, repeat all,
engines were firing before liftoff and were not shut down until they were
no longer required. High-altitude rocket-engine startup scared people
then. Hence the continuously-firing verniers, and also the unorthodox
staging concept. But the verniers were heavy, and their Isp wasn't as
good as the main engines.


The Soviets used the same "fire all motors on launch" concept on the R-7
(SS-6 "Sapwood") ICBM. I was always fascinated by their use of
interstage girders to allow the second stages of their rockets to ignite
before the first stage had finished firing; thus avoiding the use of
ullage motors to seat the second stage's propellants.
I am pretty sure we used the same technique on the Titan II ICBM.

Indeed we did. The colloquial term for it was "Fire in the Hole". If
you look at a good image of a Titan first stage (Titan Is did it, as
well) you'll see the vents for the rocket plume of the second stage.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

l (Peter Stickney) wrote in
:

In article ,
Pat Flannery writes:


Henry Spencer wrote:

One basic design principle of the original Atlas was that all, repeat
all, engines were firing before liftoff and were not shut down until
they were no longer required. High-altitude rocket-engine startup
scared people then. Hence the continuously-firing verniers, and also
the unorthodox staging concept. But the verniers were heavy, and
their Isp wasn't as good as the main engines.


The Soviets used the same "fire all motors on launch" concept on the
R-7 (SS-6 "Sapwood") ICBM. I was always fascinated by their use of
interstage girders to allow the second stages of their rockets to
ignite before the first stage had finished firing; thus avoiding the
use of ullage motors to seat the second stage's propellants.
I am pretty sure we used the same technique on the Titan II ICBM.

Indeed we did. The colloquial term for it was "Fire in the Hole". If
you look at a good image of a Titan first stage (Titan Is did it, as
well) you'll see the vents for the rocket plume of the second stage.


And an occasional spectacular burst of the first stage; I saw
this happen once on a Gemini launch and initially thought we'd
just lost a mission. Most stagings weren't like that; I assume
the upper tank dome collapsed and caused the tankage to burst.

--Damon

Peter Stickney wrote:

I am pretty sure we used the same technique on the Titan II ICBM.



Indeed we did. The colloquial term for it was "Fire in the Hole". If
you look at a good image of a Titan first stage (Titan Is did it, as
well) you'll see the vents for the rocket plume of the second stage.


I was about 99% sure of that, but didn't want to get caught in a slip;
particularly since it looks like Titan I used ullage motors on the
second stage to seat the propellants. Of course you can see the second
stage exhaust blow the interstage apart in the films of the Titan II
staging.
The really interesting staging technique is the one used between the
second and third stages of the Proton launch vehicle; in that case four
small rockets fire and in some way (I've never gotten a really precise
description of this that isn't garbled in the translation from Russian
to English) burn through _something_ (wiring? propellant plumbing?*)
that causes the second stage's motors to stop firing and initiates the
separation sequence via six forward facing solid fuel rockets mounted at
the top of the second stage. The process takes around three seconds from
the ignition of the four vernier motors on the third stage.

*The "Cosmonautics-A Colorful History" book says it's the second stage
propellant lines; but that sounds like a really good way to spray
nitrogen tetroxide all over the place. On the other hand, Chelomei
wasn't exactly a conservative designer, as the single walled bulkhead
separating the two hypergolic propellants in the Proton's second stage
shows: http://www.astronautix.com/graphics/u/ur500pol.jpg
....one pinhole leak, and it all ends spectacularly.

Pat

Damon Hill wrote:

And an occasional spectacular burst of the first stage; I saw
this happen once on a Gemini launch and initially thought we'd
just lost a mission. Most stagings weren't like that; I assume
the upper tank dome collapsed and caused the tankage to burst.


On the inflight films of staging I've seen, the dome stays intact as the
first stage backs away, but the interstage structure disintegrates.
(there's a B&W video of the staging he
http://www.geocities.com/titan_2_missile/videos.htm ...also another
video of a Titan II silo launch which does a nice recreation of the
Peenemunde A4 launch that headed toward the Luftwaffe airfield.)

Pat

On Wed, 27 Oct 2004 02:25:12 -0500, Pat Flannery
wrote:

On the inflight films of staging I've seen, the dome stays intact as the
first stage backs away, but the interstage structure disintegrates.

....Do any such films exist of the S-IV interstage blowouts?

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

On Tue, 26 Oct 2004 21:44:43 -0500, Pat Flannery
wrote:

I am pretty sure we used the same technique [open interstage] on the Titan II ICBM.

....Yup. Been some nice footage of the interstage turning into sheet
scrap when the 2nd stage fired off. Almost as interesting as the Atlas
half-stage falling off and catching fire.


OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr