n historical perspective a need for speed
TRANSCRIPT
� August 2007 BOEING FRONTIERS
n HISTORICAL PERSPECTIVE
Skystreak taught lots about flight near the sound barrierBy Michael loMBardi
As World War II was coming to a close, advances in high-speed aero-dynamics were rapidly progressing
beyond the ability of the wind tunnels of the day, prompting a dramatic expansion of flight-test research and experimental aircraft.
The National Advisory Commit-tee for Aeronautics, the predeces-sor to NASA, joined with the U.S. military to further the research of tran-sonic and supersonic flight (categorized as
A need for speed
Mach 0.8 to 1.2 and above the speed of sound, respectively). The U.S. Army Air Forces took responsibility for supersonic research—which resulted in Chuck Yea-ger breaking the sound barrier in the Bell X-1 on Oct. 14, 1947. That historic event overshadowed the highly successful re-search conducted by the pilots who flew the Douglas D-558-1 Skystreak to the edge of the sound barrier while capturing new world speed records.
The D-558-1 was developed by the Douglas Aircraft Company, today a part of Boeing, at its El Segundo (Calif.) Division. It was designed by a team led by Ed Heinemann, Douglas’s legendary chief engineer, and D-558 project engi-neer Robert Donovan.
The basic design philosophy was to build the smallest plane around the most
powerful turbine engine available. To mit-igate as much risk as possible, the team kept the design simple, using a conven-tional straight wing rather than the new and mostly unproven swept wing. The 5,000-lb.-thrust (22-kilonewton) Allison J35-A-11 engine filled the fuselage, leav-ing just enough room to house instrumen-tation and a pilot in a cramped cockpit. Because of the lack of knowledge about the survivability of a high-altitude, high-speed bailout, Douglas engineers designed a jettisonable nose section that could pro-tect the pilot until a safe bailout speed was reached.
The small wings had just enough room to store 230 gallons (871 liters) of jet fuel and the specially designed narrow wheels with high-pressure tires that were required to fit inside the minimal wheel wells of the
�BOEING FRONTIERS August 2007
n HISTORICAL PERSPECTIVE
A need for speed
airplane. Later, 50-gallon (190-liter) wing-tip tanks were added that increased the plane’s range from 490 miles to 833 miles (789 kilometers to 1,340 kilometers).
With a bright gloss-red finish to assist in visual tracking, and not being much more than a long tube with wings, the D-558-1 earned affectionate nicknames such as “The Flying Stove Pipe” and “The Crim-son Test Tube.”
In 1947, when the Skystreak first flew, there were a number of unknowns in tran-sonic flight. Of great concern was com-pressibility, or the compression of air around an airplane as it passes through a shock wave. The effects of compressibility could vary greatly based on the design of the airplane and could result in slight buf-feting all the way to loss of control. Indeed, this phenomenon had been experienced by
some piston-powered World War II air-planes in high-speed dives—most notably the P-38 Lightning.
The pilots who volunteered to fly these research planes understood the tremen-dous risks involved in literally becoming pioneers flying into the unknown. Their courage and, at times, sacrifice made an undeniable contribution to the safety of jet travel.
One of those courageous pilots was Douglas company test pilot Gene May. Between 1947 and 1949, May flew more transonic flights than any other pilot. He flew not only the D-558-1 but also the Bell X-1, in which he became the sixth person to break the sound barrier. He retired from flight testing in 1949 after proving the Douglas D558-2 Skyrocket.
On April 15, 1947, May took the Skystreak up for its first flight. Over the next four months, he pushed the bright red jet to its operational limits, flying up to 30,000 feet (9,100 meters) at a speed of Mach 0.85.
The testing amounted to 24 short flights, totaling only 9 hours and 32 minutes. But the team concluded that the Skystreak had proved itself ready for an attempt at the world speed record—and handed the plane over to the U.S. Navy.
On Aug. 20, 1947, at Rogers Dry Lake Speed Course in Muroc, Calif. (known today as Edwards Air Force Base), Cmdr. Turner Caldwell Jr. took the Skystreak for its first record-breaking flight. Caldwell averaged 640.7 mph (1,031 kilometers per hour), breaking an ear-lier record by 17 mph (27 kilometers per hour) and giving the Navy its first world
air speed record in 24 years.Four days later, Marion Carl, a major in
the U.S. Marine Corps and a World War II ace, squeezed into the tiny cockpit of the second Skystreak and bettered Caldwell’s record, with an average speed of 650.7 mph (1,047 kilometers per hour).
The three Skystreaks would continue to research transonic flight, through flights made by May, Caldwell and Carl, as well as by future X-15 pilot Scott Crossfield. Today the fully restored Skystreak No. 1 can be seen on display at the National Mu-seum of Naval Aviation in Pensacola, Fla. Skystreak No. 2 was lost along with NACA pilot Howard Lilly, the first NACA pilot to be killed in the line of duty. Skystreak No. 3 was recently restored by the Carolinas Aviation Museum in Charlotte, N.C.
The D-558-1 Skystreak and its suc-cessor, the D-558-2 Skyrocket—the first manned aircraft to reach twice the speed of sound—are a proud part of a heritage of high-speed innovation at Boeing that also includes other record-breaking research aircraft, such as the triple-sonic XB-70, the hypersonic (Mach 5 and above) X-15 rocket plane and the Space Shuttle.
Today Boeing continues its legacy of leadership in high-speed flight research with the hypersonic X-43A Hyper-X that has reached speeds in excess of Mach 7. This program expanded our knowledge of high-speed flight that someday could allow airline passengers to measure their transoceanic flights in minutes rather than hours. n
As shown in this head-on view, the D-558-1 Skystreak featured a clean and simple design. That design reflected the simple philosophy for this aircraft: Build the smallest plane around the most powerful turbine engine available.
The first pilots of the Skystreak included (from left) u.S. marine Corps maj. marion Carl, Douglas test pilot Gene may and u.S. Navy Cmdr. Turner Caldwell Jr.
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