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Atlas B

 

 

 

ATLAS PROGRAM BACKGROUND
Written and Edited by Cliff Lethbridge

 

Originally developed as the first U.S. ICBM weapons system, the Atlas program rapidly evolved into an extremely viable and successful family of space boosters which remain in use today.

Atlas vehicle design can be traced back to the days following the conclusion of World War II.

In a letter issued on October 31, 1945, the U.S. Army Air Technical Service Command invited proposals from manufacturing concerns on the broad-based design of unmanned flying vehicles capable of carrying a weapons payload 20 to 5,000 miles.

Although this would have seemed preposterous several years earlier, the concept of unmanned vehicles carrying destructive weapons over great distances had been validated to the satisfaction of the U.S. military by the lethal German V-2 missile during World War II.

Consolidated Vultee Aircraft Corporation (Convair) based in San Diego, California, presented several design proposals for consideration.

On January 10, 1946, Convair was given military funding to begin preliminary design work on a class of missile capable of delivering a weapons payload 6,000 miles or greater, even surpassing the requirements originally requested.

Convair engineers first set about reviewing as many German missile documents as they could get their hands on. Both ballistic missile and more conventional jet-powered winged cruise missile concepts were explored.

By the end of 1946, Convair canceled its cruise missile efforts, perceiving that competitors had developed successful designs. Indeed, preliminary designs for Northrup's Snark and the Martin Company's Matador cruise missiles were already on the drawing board at the time.

But pioneering ballistic missile research continued at Convair, and the company received about $2 million to build ten missiles for flight testing under the MX-774 "Hiroc" (High-Altitude Rocket) designation on April 19, 1946.

Design work for the MX-774 began at Vultee Field near Downey, California in June, 1946. Originally, three distinct versions of the MX-774 were considered. The first, called MX-774 Design A and nicknamed "Teetotaler" because it did not burn alcohol, resembled a cruise missile.

MX-774 Design B, nicknamed "Old Fashioned" due to its resemblance to the V-2, was designed as a supersonic test vehicle. MX-774 Design C, nicknamed "Manhattan" due to its presumed nuclear capability, was intended to be an operational missile.

Ultimately, only the Design B version of the MX-774 was built. Fabrication of the missiles began in the fall of 1947. The first MX-774 static engine test firing was conducted on November 14, 1947.

Remarkably, this MX-774 design contained technical innovations which would actually carry through to today's Atlas vehicles, effectively laying a foundation for major breakthroughs in post-war rocketry.

These included a single-wall construction made of stainless steel rolled so thinly that the missile body had to be pressurized to keep from collapsing like a balloon.

The missile's propellants would inflate the main missile body and make it rigid, thus saving weight by eliminating the need for an internal support structure.

In the Atlas missile ultimately introduced, the skin weighed less than 2% of the fuel it carried. If the skin's thickness varied by as little as 1/1,000 of an inch, the missile's weight could increase by 100 pounds and its range could decrease by 100 miles.

The MX-774 also featured a separating nose cone which could carry scientific instrumentation or a weapons payload. This also saved critical weight since the missile body itself did not require aerodynamic equipment to guide it to a precision impact.

In addition, the missile incorporated a gimbaled engine exhaust nozzle to facilitate steering. While other ballistic missiles of the day, including the German V-2, used exhaust deflector vanes to guide the missile, gimbaled engines would set a new standard.

Giving credit where credit is due, it was Reaction Motors, Inc. and not Convair that actually developed the gimbaled engine exhaust nozzle that was adapted for use on the MX-774.

Despite this groundbreaking effort, the MX-774 project was canceled on July 1, 1947. This was just three months before the missile's first scheduled test-flight. Pentagon leadership initially felt that long-range ballistic missiles, still an unproven technology, would compete for funding with traditional manned heavy bombers.

However, the grandfather of the modern Atlas did not die. Some of the MX-774 funding remained available after official cancellation, and Convair was given permission to build and test-launch three of ten missiles originally authorized.

The first missile was completed in October, 1947. It was test-fired on a static launch stand at Convair's Ft. Loma facility on November 14, 1947. Several more static test-firings were conducted in the following months.

Static engine tests were completed by May, 1948. The first MX-774 was then trucked to the White Sands Missile Range in New Mexico for flight testing. It was erected at an old, modified V-2 launch platform.

Indeed, the MX-774 was described as a "streamlined" version of the German V-2. The missile was 31 feet, 7 inches long by 2 feet, 6 inches wide and had a finspan of about 6 feet. It weighed 1,200 pounds empty.

The first MX-774 static engine firing on the launch platform was conducted on May 26, 1948. Several more static test-firings followed. The first MX-774 was launched on July 13, 1948. The missile's propulsion system shut down unexpectedly about one minute into the flight, causing it to crash prematurely.

Much of the wreckage was recovered and examined, and it was concluded that a major flaw in missile hardware probably did not cause the engine cutoff.

The second MX-774 was launched on September 27, 1948. It flew to a height of 40 miles before breaking up due to an undetermined malfunction. However, flight dynamics were verified, and useable data was transmitted from the missile to the ground during the test.

The third and last MX-774 was launched on December 2, 1948. A mysterious propulsion system cutoff similar to that experienced in the first test-flight occurred, although the missile reached a higher altitude before dropping to the ground.

Convair continued ballistic missile research and design work following the expiration of the MX-774 project. At the time, U.S. Air Force funding centered around more conventional winged cruise missile applications, most notably the Navajo, built by North American.

Regardless of this funding situation, Convair conceived another pioneering mainstay of the eventual Atlas missile in 1949. This was the "one and one-half stage" propulsion system.

In this configuration, a series of "booster" and "sustainer" engines would all be ignited at liftoff. During the flight, the booster engines would shut down, then be jettisoned along with their associated fairing structure.

The sustainer engines would remain burning after jettison of the booster engines, remaining attached to the vehicle for the duration of its flight.

While a debate still rages as to whether or not a configuration whereby all engines are ignited at liftoff can truly be defined as more than one stage, the "one and one-half stage" description has stuck with Atlas vehicles ever since.

It was also in 1949 that the U.S. military showed a renewed interest in ballistic missile technology. In August of that year, the Soviet Union exploded their first atomic weapon.

The start of the Korean War on June 25, 1950 indicated yet another need to press ahead with long-range missile development. On January 23, 1951, Convair was granted a contract under what was called the MX-1593 project.

The U.S. Air Force sought to determine the most effective method of delivering nuclear weapons over vast distances. Again, winged cruise missiles were pitted against ballistic missiles, although both would eventually be approved.

When the MX-1593 contract was issued, Convair already had available for the U.S. Air Force detailed ballistic missile design proposals that had been refined in-house following the expiration of the MX-774. The company offered design proposals for both pure ballistic and semi-ballistic concepts.

In the pure ballistic approach, the missile would fly a ballistic pattern to its target. In the semi-ballistic approach, the missile would be launched in a ballistic pattern, but would glide toward its target using wings.

A firm decision was made by the U.S. Air Force to press ahead with Convair's pure ballistic missile warhead delivery system in September, 1951. It was decided that the semi-ballistic version would be too easy to intercept. Even though a pure ballistic guidance system had yet to be developed, the semi-ballistic approach was scrapped.

The MX-1593 stage of Atlas development is worthy of special note because the name of the long-lived missile and rocket program was approved at that time. In January, 1951, Convair engineer Karel J. Bossart proposed the name "Atlas" for the company's missile.

It was perhaps a bit optimistic at the time to assume that an "Atlas" missile fleet would "carry the world on its shoulders" like its Greek god namesake.

It was somewhat more apparent that the "Atlas Corporation" was the parent company of Convair, and perhaps deserved special tribute. Other names considered by Convair included "Boxcar" and "Hot Rod".

The U.S. Air Force approved the name "Atlas" for the Convair missile program in August, 1951, although a few more changes in numerical designations were in store.

The "Atlas Missile" was briefly reclassified as the "Atlas Bomber" and designated B-65 late in 1951. Early in 1952, the "Atlas Bomber" was reclassified as the "Atlas Missile" and designated SM-65.

In July, 1952, the U.S. Air Force allocated additional funds to the Atlas program. After a progress review in December of the same year, a decision was made to continue development of the missile.

Soon afterward, the U.S. Air Force gave the Atlas its highest priority rating of "1A" and went forward on what is best described as a "crash course" development program. The new U.S. rush to develop an operational ICBM was primarily due to the "cold war" combined with scientific advances of the day.

In 1953, the U.S. Atomic Energy Commission produced a classified report indicating that nuclear weapons would soon be produced that could be light and small enough to carry aboard an ICBM.

It was also apparent that the Soviet Union was well underway with its own missile programs, which combined Soviet research with captured German V-2 technology. U.S. missile programs, including Atlas, were accelerated due to this very tangible military threat.

Convair recommended that Atlas test missiles similar to the proposed operational ICBM be produced to validate the missile's airframe, launch systems and propulsion hardware. Any potential problems with the basic missile design could be ironed out in this test phase.

Convair and the U.S. Air Force determined that the fabrication of test missiles which closely resembled an operational model could quicken the development of an operational weapons system by as much as a year.

The risk of uncovering a major flaw which might scuttle the entire Atlas program was outweighed by the time savings leading to ultimate deployment of the missile.

Therefore, U.S. Air Force approval was given to Convair for the development of two series of Atlas test missiles in May, 1953. The first Atlas test series was designated X-11, while the second, more advanced test series, was designated X-12.

By 1954, Solar Aircraft Company completed the first Atlas thin-skin tank. In August of the same year, the missile's design was modified to accommodate practical improvements in nuclear warhead design.

In October, 1954, a decision was made to make the most significant Atlas modification to date. This was a reduction from a planned five engines to three. Since nuclear weapons payloads had become smaller and lighter, less overall thrust would be needed to carry them.

The five-engine Atlas would have been 90 feet long and 12 feet wide, while the first three-engine Atlas actually introduced was scaled down to 75 feet, 10 inches long and 10 feet wide.

The Atlas missile design was frozen in December, 1954. On December 16, 1954 Convair and the U.S. Air Force made the first official public announcement that Atlas production was underway. Atlas was intended to be revealed by its code name "Model 7" but in fact the name Atlas had appeared in Aviation Week magazine as early as March 8, 1954.

After an intensive series of inspections of Atlas production designs, the U.S. Air Force officially issued to Convair a contract for the long-term continuation of the Atlas program on January 14, 1955.

The Atlas was given its final numerical designation of Weapons System-107A (WS-107A), calling for a missile capable of carrying a nuclear payload 6,000 to 9,000 miles with a circular error of not more than ten miles.

It should be noted that some sources exclusively refer to the Atlas weapons system as WS-107A-1. This is primarily due to the fact that the Titan missile program was later designated WS-107A-2.

Since the Titan was designed well after Atlas development was already underway, the initial designation of WS-107A alone is historically accurate for the Atlas missile.

However, it is equally acceptable to refer to the Atlas program as WS-107A-1 for the specific purpose of contrasting it with the Titan designation of WS-107A-2. Strictly speaking, both missiles were initiated under WS-107A, with Atlas being first and Titan second.

Upon receiving the WS-107A production contract, Convair subsequently began construction of a new facility called Convair Astronautics based in Kearney Mesa, outside San Diego, California.

In May of 1955, the U.S. Air Force inspected a mock-up of the Atlas missile, and about three months later gave their final approval for the construction of the first operational test vehicles.

The first Atlas missile was completed in August, 1956, although this missile was not built for flight. It was delivered to the U.S. Air Force for static systems testing at Sycamore Canyon, California on August 29, 1956.

The first Atlas to arrive at Cape Canaveral was a dummy version designed to test compatibility of the Atlas body with launch systems. At the time, Atlas missiles were too large to transport by aircraft. Instead, the missile had to be transported aboard a specially designed truck trailer.

The Atlas "cradle" which delivered the missile from the factory to the launch pad was built by Goodyear Aircraft Corporation. It was 64 feet long by 14 feet wide and required two "back-seat" drivers to maneuver the vehicle around turns. The dummy Atlas left San Diego aboard such a trailer on October 1, 1956.

The trip was arduous, at best. Due to the size of the trailer, tight turns and all bridges and underpasses under 13 feet, 10 inches high were avoided. To maintain security, detours were made around large cities and a police escort was employed.

The journey was made in daylight hours only, and resulted in numerous pit and overnight stops. The missile body itself was shrouded in an aluminum-colored canvas. During this maiden trip, security officials were reportedly dismayed during a pit stop when a child identified the "secret" cargo as an Atlas missile.

The first Atlas completed its 2,622-mile journey to the Cape in nine days. A flight-ready Atlas would soon be able to cover the equivalent distance in about 18 minutes.

The first flight-ready Atlas, designated Atlas #4A, was received at Cape Canaveral in December, 1956. The foundation was thus laid for a plethora of Atlas missile and rocket launches which followed.


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