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Version of the Atlas II with no sustainer?



 
 
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  #1  
Old September 19th 04, 02:20 AM
Explorer8939
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Default Version of the Atlas II with no sustainer?

I vaguely recall that in the long era of the 1990s, there were a few
Atlas II launches did not carry the small sustainer engines, but
rather just the two booster engines, which fired until all propellant
was consumed. Was this just a dream, or did Lockheed build a few of
these?

Or am I simply confusing Atlas III with Atlas II?
  #2  
Old September 19th 04, 05:13 AM
Jim Davis
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Explorer8939 wrote:

I vaguely recall that in the long era of the 1990s, there were a
few Atlas II launches did not carry the small sustainer engines,
but rather just the two booster engines, which fired until all
propellant was consumed. Was this just a dream, or did Lockheed
build a few of these?

Or am I simply confusing Atlas III with Atlas II?


The Atlas II had the 3 chamber (2 booster, 1 sustainer) Rocketdyne
MA-5A engine. The Atlas III has the 2 chamber RD-180.

The MA-5A did not have the two small vernier engines that previous
Atlas engines had. Could that be what you are thinking of?

Jim Davis

  #3  
Old September 19th 04, 05:21 PM
Pcrecycling1
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I vaguely recall that in the long era of the 1990s, there were a
few Atlas II launches did not carry the small sustainer engines,


pcrecycling1

this is true
  #4  
Old September 20th 04, 12:13 PM
John Pelchat
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It seems that this question has two possible replies but to get the
answers is going to take someone who has access to their resources. I
was not entirely clear on the original question so I will take a shot,
hoping folks remember that I am doing this from memory with NO
references.

At liftoff, the sixties-era Atlas (such as the types that served as
ICBM's and as the Mercury booster) had five engines running. At the
base were two outboard booster engines, and a centerboard sustainer
engine. In addition, two vernier engines were on the side of the
vehicle. If the question asks about an Atlas configuration without
the centerboard sustainer, I believe that only early test versions of
Atlas flew this way while the vehicle was under initial development
and no operational versions of Atlas flew this way. If on the other
hand, the question refers to the two vernier engines, later versions
of Atlas (Atlas III or V) deleted the two vernier engines.

I am hoping others will correct my mistakes and provide either
corrections or amplifications.

Take care . . .

John M. Pelchat
  #5  
Old September 20th 04, 04:28 PM
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Jim is correct. No Atlas II ever flew without a sustainer engine, but
Atlas II did delete the two small side-mounted vernier engines that
were on earlier Atlas vehicles.

General Dynamics was working on a new design called Atlas IIAR, that
would have replaced the booster/sustainer MA-5A engine with a straight
two-chamber design. Rocketdyne bid an engine design. So did Russia's
Energomash (in combo with Pratt). Energomash won when Rocketdyne
pulled out of the competition. Eventually, General Dynamics space
division was sold to Martin Marietta, which was later merged into
Lockheed Martin - and the new Atlas IIAR was renamed "Atlas III".
Lockheed used the new Atlas as the starting point for its EELV design -
which it called "Atlas V". Next year, the last Atlas III will fly and
Lockheed will shut down the last remnants of the long-running
Convair/General Dynamics heritage Atlas program at the Cape.

- Ed Kyle

  #6  
Old September 21st 04, 12:37 PM
John Pelchat
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wrote in message roups.com...
Jim is correct. No Atlas II ever flew without a sustainer engine, but
Atlas II did delete the two small side-mounted vernier engines that
were on earlier Atlas vehicles.

General Dynamics was working on a new design called Atlas IIAR, that
would have replaced the booster/sustainer MA-5A engine with a straight
two-chamber design. Rocketdyne bid an engine design. So did Russia's
Energomash (in combo with Pratt). Energomash won when Rocketdyne
pulled out of the competition. Eventually, General Dynamics space
division was sold to Martin Marietta, which was later merged into
Lockheed Martin - and the new Atlas IIAR was renamed "Atlas III".
Lockheed used the new Atlas as the starting point for its EELV design -
which it called "Atlas V". Next year, the last Atlas III will fly and
Lockheed will shut down the last remnants of the long-running
Convair/General Dynamics heritage Atlas program at the Cape.

- Ed Kyle



Ed,

Good morning. You seem to have provided the answer I think he was
looking for. Now I have one. Was the 2 booster noozles/1 sustainer
nozzle as considered to be one MA-5A engine? Did the Atlas sustainer
and boosters share a lot of equipment that made them suitable to
consider it all one engine? if so, it must have taken a lot of
engineering to design it such that when the booster skirt was
jettisoned, that the shared equipment came a part in such a way that
the sustainer had what ever it needed to continue to operate. If you
know of one, please suggest an on-line resource where I could learn
more about how Atlas was designed and operated.

Off topic but related: Later designs (such as the S-1C stage of Saturn
V with five F-1's) had seperate engines. Was the first stage of Titan
II considered to have two engines, or an single engine with two
nozzles?
  #7  
Old September 21st 04, 11:11 PM
ed kyle
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(John Pelchat) wrote in message . com...


Was the 2 booster noozles/1 sustainer
nozzle as considered to be one MA-5A engine? Did the Atlas sustainer
and boosters share a lot of equipment that made them suitable to
consider it all one engine?


According to Boeing:

"The Rocketdyne MA-5A propulsion *system* consists of a
429,500 lb thrust booster *engine* with two thrust *chambers* and
a 60,500 lb thrust sustainer *engine* all using liquid oxygen and
RP-1 as propellants. ... Both bell-shaped booster thrusters are
connected to a central power package consisting of a turbopump
for each chamber, a single gas generator, a pneumatic control
package, and a liquid oxygen regulator. The sustainer engine
turbopump is engine-mounted."

So Boeing considered it a system consisting of two engines -
a two chambered booster and a single-chambered sustainer.

... it must have taken a lot of
engineering to design it such that when the booster skirt was
jettisoned, that the shared equipment came a part in such a way that
the sustainer had what ever it needed to continue to operate.


You betcha. Atlas development was part of one of the largest
military-industrial efforts ever marshalled by the United
States. Atlas was a troubled bird for quite a few years.
Go see a real Atlas at Cape Canaveral (not Kennedy Space Center)
or the one in Huntsville to get an idea of how complicated the
engine section was.

Was the first stage of Titan
II considered to have two engines, or an single engine with two
nozzles?


According to the U.S. Air Force:

"Titan II was boosted by an Aerojet LR87-AJ-5 two chamber
liquid propellant rocket engine of 430,000 lbs. thrust"

- Ed Kyle
  #8  
Old September 22nd 04, 01:38 AM
Mike Walsh
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"Explorer8939" wrote in message
om...
I vaguely recall that in the long era of the 1990s, there were a few
Atlas II launches did not carry the small sustainer engines, but
rather just the two booster engines, which fired until all propellant
was consumed. Was this just a dream, or did Lockheed build a few of
these?

Or am I simply confusing Atlas III with Atlas II?


Back when the first Atlas missiles were flown the first test vehicles
had only the two booster engines and the propulsion system was
not separated. This was back in 1957-58.

I don't know of any later Atlas missiles that didn't have the sustainer
engine until the Atlas III.

Mike Walsh


  #9  
Old September 22nd 04, 02:08 AM
Damon Hill
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(John Pelchat) wrote in
om:


Good morning. You seem to have provided the answer I think he was
looking for. Now I have one. Was the 2 booster noozles/1 sustainer
nozzle as considered to be one MA-5A engine? Did the Atlas sustainer
and boosters share a lot of equipment that made them suitable to
consider it all one engine? if so, it must have taken a lot of
engineering to design it such that when the booster skirt was
jettisoned, that the shared equipment came a part in such a way that
the sustainer had what ever it needed to continue to operate. If you
know of one, please suggest an on-line resource where I could learn
more about how Atlas was designed and operated.


The booster engines and the sustainer have separate turbopump
assemblies, so I think they could be considered an engine set, but not
a single engine. On separation, the booster engine package slides down
a pair of rails taking its turbopump assembly with it; there are a
couple of propellant disconnects plus other plumbing/electrical
connections, but otherwise the engines are functionally separate, I
believe.

Off topic but related: Later designs (such as the S-1C stage of Saturn
V with five F-1's) had seperate engines. Was the first stage of Titan
II considered to have two engines, or an single engine with two
nozzles?


Two combustion chambers powered by a single turbopump, as I recall.
The nozzles steer independently so can provide roll control without
verniers. I consider a turbopump/multiple combustion chamber package
to be a single engine; opinions vary. The RD-180 is similar; it was
derived from the four-chamber RD-170 but I'm not clear if the latter
had a single turbopump or a pair, each feeding a pair of nozzles.

Atlas originally used steerable verniers and Atlas II replaced them with
roll thrusters (hydrazine monoprop?). I assume the verniers got their
propellants tapped off the sustainer's turbopumps.

Atlas III and V of course are similar to Titan in the use of steerable
nozzles; Delta IV's single RS-68 ducts its turbopump exhaust through
nozzles on each side of the main engine; one of the nozzles is
steerable and provides the roll control. If I recall correctly,
Delta II has two steerable verniers at the base of the first stage.

(more information than you probably wanted to know, yes?)

--Damon
  #10  
Old September 22nd 04, 06:40 AM
Pat Flannery
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ed kyle wrote:




... it must have taken a lot of
engineering to design it such that when the booster skirt was
jettisoned, that the shared equipment came a part in such a way that
the sustainer had what ever it needed to continue to operate.



You betcha. Atlas development was part of one of the largest
military-industrial efforts ever marshalled by the United
States. Atlas was a troubled bird for quite a few years.
Go see a real Atlas at Cape Canaveral (not Kennedy Space Center)
or the one in Huntsville to get an idea of how complicated the
engine section was.


It's fairly involved back the
http://www.siloworld.com/ICBM/ATLAS/ATE/TRANS13.jpg
http://www.geocities.com/atlas_missile/diagrams.html
http://www.geocities.com/atlas_missi...tdyne_ma5a.jpg
Speaking of involved Atlas's, did anyone have this model when they were
a kid? I had it at least three times:
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?

According to the U.S. Air Force:

"Titan II was boosted by an Aerojet LR87-AJ-5 two chamber
liquid propellant rocket engine of 430,000 lbs. thrust"


Don't ever get Henry Spencer started on this one... trust me. ;-)


Pat

 




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