One of the greatest efforts, and adventures, in history has been the race between the US and the Soviet Union (USSR) to put the first man in space. As we now know, the USSR "won" the initial race by putting the first man, Yuri Gagarin of the Soviet Air Force, in space. The US soon responded by putting an American in space, then two, and then finally men on the moon.
The gargantuan efforts that went into the US space effort, Projects Mercury, Gemini, and Apollo, are a matter for the historical record, and we can find that out from any number of books. But ours is the story of a project that few of us get to hear about. The project is seldom remembered of outside the world of engineers who work on space, but that project has had probably as much impact on modern space flight as anything else. Project X-15, "Rocketship X-15" (see figure 1), blazed a path that can be traced to the Space Shuttles we see today.
Figure 1: Side and front view of the X-15. Note that the X-15 uses skids instead of wheels for its landing gear to save weight.
The X-15 was the fifteenth of a line of experimental (that is what the X stands for) aircraft that started with the famous X-1 "Glamorous Glennis." The X line of aircraft started in 1945 when the US Army Air Force needed an aircraft that could fly faster than the speed of sound to help them design the next generation of US fighter planes. The speed of sound, usually known as Mach 1, is 760 mph (1216 km per hour) at sea level and 670 mph (1072 km per hour) at 30,000 feet (9,091 meters) and above. Near the end of the Second World War, when fighter planes started reaching those speeds, they started breaking up in flight. Some people started saying that there was a wall out there that would destroy anyone trying to go faster than the speed of sound. They called that wall the "sound barrier. Those people were wrong, there was no scientific basis for that idea, and a young Air Force Captain called Charles E "Chuck" Yeager proved them wrong in the Bell X-1 that he had named "Glamorous Glennis" after his wife.
By 1952, the US Army Air Force had become the US Air Force, and the USAF needed to see what would happen when they tried to fly faster than Mach 3 (that is three times the speed of sound) at heights of 100,000 feet (30,300 meters) and higher. They needed another X-plane and they had North American Aviation make them the X-15. In the nine years from 1959 to 1968, the X-15 would set the record for the most successful experimental aircraft in US history.
The X-15 was designed for two things: to fly faster and higher than anything else. It was basically a rocket with wings and just enough extra space to hold a pilot ( see figure 2). At six times the speed of sound and higher, the X-15's skin was expected to reach temperatures of 1,200 degrees Fahrenheit (649 degrees Celsius)! At those temperatures, normal steel and aluminum become weak, so the X-15 was made of Titanium and a new alloy called Inconel-X. These metals were so exotic that North American had to learn how to use them as they made the plane.
The X-15 was expected to fly higher than 200,000 feet, that is more than 37 miles. At those heights there is so little air left in the atmosphere that the normal methods for controlling an aircraft don't work, the X-15 was like a spaceship at those altitudes (see figure 5). Therefore, the X-15 had a set of 12 reaction jets in its nose and wing
Figure 2: Cutaway view of the X-15. The compartment behind the pilot held the instruments to monitor the flight, the rest was mostly fuel tanks for the rocket engine.
tips, by using these jets, the pilot could move the nose of the X-15 up, down, or sideways while he was above most of the atmosphere. To save weight, the X-15 was designed to be taken up under the wing of a B-52 bomber (see figure 3) and then released before its rocket engine was started (see figure 4). By the time the X-15 program ended with the 199th flight in October 1968, the two X-15s had flown up to Mach 6.33 at up to 354,200 feet (107,333 meters). That is more than sixty seven miles above the surface of the Earth.
Figure 3: B-52 bomber taking off from Edwards Air Force Base in California with the X-15 under its Right wing. The B-52 was called the "Mother Ship" for the X-15.
Figure 4: The X-15 immediately after being released by the Mother Ship. The Rocket engines in the X-15 haven't started yet. In essence, the X-15 is falling like a bomb at this stage!
Figure 5: A Typical X-15 mission. Because the X-15 was flying so fast, it took a long time to turn. Therefore, the flight was kept straight. The Mother Ship would fly to the Idaho border with the X-15 under it from Edwards Air Force Base, turn around and release the X-15. The X-15 would then take about fifteen minutes to get to California.
In a typical X-15 mission, the pilot would put on a flying suit that was actually a space suit (the same space suit that was worn by the Mercury Astronauts) about six hours before the flight. Then the pilot would get into the X-15 and it would be sealed. The B-52 Mother Ship would then take off from Edwards Air Force Base (see figure 5) in California and head for the Idaho Border. Over the Idaho border, the B-52 would turn around and point towards California. The X-15 would then be released. The rocket engines would still be off at this time, that was to avoid blowing up the B-52 (see figure 4). As soon as the engines were ignited, the X-15 would go almost straight up, beyond 99.9 percent of the Earth's atmosphere. At this stage, the pilot of the X-15 would be flying a spaceship. The X-15 would then come down, and land back at Edwards Air Force Base.
A lot of people think that the X-15 was probably the first into space. Space is defined to be the height at which there is no atmosphere. According to those people, there is practically no atmosphere more than fifty miles above the Earth. They also think that
the X-15, an aircraft flown by a pilot that flew through the atmosphere and then beyond into space was the right way to go. In fact, the engineer in charge of the X-15 program, Harrison Storms, actually proposed a redesigned X-15 (see fig 5) that would probably have put man into space before project Mercury. But that idea was proven irrelevant by politics and history.
Figure 5: The final design proposed for the X-15. In one of these ideas, this X-15 would be mounted atop a Titan rocket instead of under the B-52 and then shot straight up into space like the Mercury capsules. Only, unlike the Mercury capsule, the X-15 would fly in and land like a plane. Like the Shuttle, only twenty years early.
The X-15 is still considered the most successful experimental aircraft program. The lessons learnt in that program helped in the design and construction of the space craft that followed and the NASA Space Shuttle constructed by Rockwell International.
The company that made the X-15, North American Aviation, is now known as Rockwell International.
The two leading engineers in the X-15 program, Harrison Storms and Charley Felts, went on to build the Apollo spacecraft.
And two of the test pilots who flew the X-15 are Donald Engl. and Neil Armstrong.
Things to know:
Colonel Yuri Gagarin, Soviet Air Force
Alan Sheppard, NASA
Project Mercury
Project Gemini
Project Apollo
Orbital flight
The X planes
Speed of Sound
Sound Barrier
Mach number
Sea Level
General Charles E "Chuck" Yeager
Supersonic
Rocket Engines
Alloy
Titanium
Inconel X
Supporting material:
The movie, "The Right Stuff"
The X-planes: X-1 to X-30. Miller, Jay, Specialty Press, Marine on St. Croix, MN, 1988
"The History of Manned Space Flight", baker, David, New Cavendish Books, London, England, 1981
"Yeager, An Autobiography", Yeager, Charles E, General USAF, bantam Books, NY, NY, 1985
"The Right Stuff", Wolfe, Tom.
"The X-15 Diary, the Story of America's First Space Ship", Tregaskis, Richard, E P Dutton & Co., NY, NY, 1961
"Angle Of Attack: Harrison Storms and the Race to the Moon", Gray, Mike, NY, NY, 1992
Sunday, 01-Aug-2004 00:36:47 CDT
CSR/TSGC Team Web
