Balloon tank
Encyclopedia
A balloon tank is a style of fuel tank used in the Atlas ICBM and Centaur
upper stage that does not use an internal framework, but instead relies on a constant internal pressurization to keep its shape.
Balloon tanks are very light, and this permits a good propellant mass fraction.
One disadvantage of balloon tanks is that if pressurisation fails, the vehicle collapses.
, who designed both the Atlas and Centaur rockets for the U.S. Air Force
and NASA
. Constructed of very thin stainless steel, the tanks, prior to integration into the Atlas or Centaur rocket body, are inflated with nitrogen to give the tanks their shape and strength. While other rockets, including the Titan and Saturn rockets (and even the Space Shuttle's external tank) can remain rigid due to the internal framework, balloon tanks must always remain pressurized, as any drop in pressurization will result in the failure of the vehicle.
. Instead of the traditional internal framework used on the rockets available at that time (especially the Redstone IRBM, a direct descendant of the V-2 rocket), the Atlas ICBM
designers used the balloon tank concept to lighten the rocket enough to hurl a 5 megaton thermonuclear warhead onto a target in the former Soviet Union
from a launch pad in continental USA. This tank technology made feasible a relatively simple stage-and-a-half design for Atlas instead of the more complicated staging used in later Titan
ICBMs.
After its initial development in the Atlas rocket, Bossart used the same technology with the high-energy Centaur
upper stage. The Centaur rocket, fueled with liquid hydrogen and powered by an RL10 engine, was originally planned to be used with the Saturn V
rocket for high-energy missions to the Solar System, but was later adapted for use as part of the Atlas and Titan rockets.
In May 1963 at Vandenberg Air Force Base
an Atlas/Agena vehicle under static testing suffered a pressurisation failure leading to the total collapse of the vehicle. Fortunately, only a dummy payload was installed.
With the introduction of the Atlas V
EELV, balloon tanks and half-staging are no longer used on the Atlas rocket. Centaur, however, retains this feature and it has not undergone a single catastrophic failure since the Atlas V's first flight.
Centaur (rocket stage)
Centaur is a rocket stage designed for use as the upper stage of space launch vehicles. Centaur boosts its satellite payload to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity...
upper stage that does not use an internal framework, but instead relies on a constant internal pressurization to keep its shape.
Balloon tanks are very light, and this permits a good propellant mass fraction.
One disadvantage of balloon tanks is that if pressurisation fails, the vehicle collapses.
Design
Balloon tanks get their name from the cylindrical party balloons which inspired Karel BossartKarel Bossart
Karel Jan Bossart was a pioneering rocket designer and creator of the Atlas ICBM...
, who designed both the Atlas and Centaur rockets for the U.S. Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
and NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
. Constructed of very thin stainless steel, the tanks, prior to integration into the Atlas or Centaur rocket body, are inflated with nitrogen to give the tanks their shape and strength. While other rockets, including the Titan and Saturn rockets (and even the Space Shuttle's external tank) can remain rigid due to the internal framework, balloon tanks must always remain pressurized, as any drop in pressurization will result in the failure of the vehicle.
History
The use of balloon tanks in the Atlas ICBM was the brainchild of rocket designer Karel BossartKarel Bossart
Karel Jan Bossart was a pioneering rocket designer and creator of the Atlas ICBM...
. Instead of the traditional internal framework used on the rockets available at that time (especially the Redstone IRBM, a direct descendant of the V-2 rocket), the Atlas ICBM
Intercontinental ballistic missile
An intercontinental ballistic missile is a ballistic missile with a long range typically designed for nuclear weapons delivery...
designers used the balloon tank concept to lighten the rocket enough to hurl a 5 megaton thermonuclear warhead onto a target in the former Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
from a launch pad in continental USA. This tank technology made feasible a relatively simple stage-and-a-half design for Atlas instead of the more complicated staging used in later Titan
LGM-25 Titan
The SM-68 Titan was the designation for two American intercontinental ballistic missiles, which were members of the Titan family of rockets...
ICBMs.
After its initial development in the Atlas rocket, Bossart used the same technology with the high-energy Centaur
Centaur (rocket stage)
Centaur is a rocket stage designed for use as the upper stage of space launch vehicles. Centaur boosts its satellite payload to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity...
upper stage. The Centaur rocket, fueled with liquid hydrogen and powered by an RL10 engine, was originally planned to be used with the Saturn V
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...
rocket for high-energy missions to the Solar System, but was later adapted for use as part of the Atlas and Titan rockets.
In May 1963 at Vandenberg Air Force Base
Vandenberg Air Force Base
Vandenberg Air Force Base is a United States Air Force Base, located approximately northwest of Lompoc, California. It is under the jurisdiction of the 30th Space Wing, Air Force Space Command ....
an Atlas/Agena vehicle under static testing suffered a pressurisation failure leading to the total collapse of the vehicle. Fortunately, only a dummy payload was installed.
With the introduction of the Atlas V
Atlas V
Atlas V is an active expendable launch system in the Atlas rocket family. Atlas V was formerly operated by Lockheed Martin, and is now operated by the Lockheed Martin-Boeing joint venture United Launch Alliance...
EELV, balloon tanks and half-staging are no longer used on the Atlas rocket. Centaur, however, retains this feature and it has not undergone a single catastrophic failure since the Atlas V's first flight.