Starbuster: 55 years ago Capt. Mel Apt conquered Mach 3, lost life on fated flight
Capt. Milburn G. “Mel” Apt stands in front of the Bell X-2. Apt was the first person to fly faster than Mach 3, which he accomplished Sept. 27, 1956 on a flight that cost him his life. (Courtesy photo)
by Peter W. Merlin
NASA Dryden History Office
10/5/2011 - EDWARDS AIR FORCE BASE, Calif. -- It has been 55 years since Capt. Milburn G. "Mel" Apt piloted a Bell X-2 to more than three times the speed of sound during a flight that cost the cool-headed aviator his life.
On Sept. 27, 1956, Captain Apt flew a near perfect flight profile in the rocket-powered Bell X-2, achieving a speed of 2,094 miles per hour - Mach 3.196. Unfortunately, upon turning the X-2 back toward Edwards, Apt tumbled out of control. Knocked unconscious after separating his escape capsule, he was unable to complete the bailout sequence and perished when the capsule struck the ground.
Air Force Flight Test Center Museum staff, volunteers, and base archaeologists visited the impact site on the anniversary to pay tribute to a fallen hero.
The quest for Mach 3
By the mid 1950s, test pilots had conquered speed milestones of Mach 1 and Mach 2 in the skies above Edwards, and had flown above 90,000 feet. Seeking to fly higher and faster, researchers pressed forward with efforts to fly an airplane to altitudes above 100,000 feet at speeds in the Mach 3 range. Toward these goals, Bell Aircraft Corporation produced the X-2, nicknamed "Starbuster," to investigate the problems of aerodynamic heating, stability, and control effectiveness at high speeds and altitudes. The X-2 project was an integrated and cooperative effort between the Air Force, Bell, Curtiss-Wright Corporation, and the National Advisory Committee for Aeronautics.
The X-2 was a sleek swept-wing craft built of K-Monel® steel alloy and powered by a liquid-fueled, dual-chamber rocket engine. For emergencies, it was equipped with a detachable nose section that served as an escape capsule. Its small parachute was meant only to stabilize the capsule until the pilot could bail out at a safe altitude. As with the earlier X-1 series of rocket planes, a B-50 bomber carried the X-2 to launch altitude and released it. Glide and rocket-powered flights ended with landings on the dry lakebed at Edwards.
Bell built two X-2 aircraft, serial numbers 46-674 and 46-675, at the company's plant in Buffalo, New York. While Bell technicians fitted 674 with a Curtiss-Wright XLR25-CW-1 rocket engine, the second X-2 began glide tests at Edwards. Bell test pilot Jean "Skip" Ziegler made the first two flights, followed by a familiarization flight for Lt. Col. Frank K. "Pete" Everest, the primary Air Force project pilot. The vehicle was then was then returned to Buffalo for engine installation, but an explosion during a captive flight claimed it before it could be returned to Edwards for powered flight-tests.
Everest piloted the remaining X-2 on its first unpowered flight on August 5, 1955, and its first rocket-powered flight on November 11. He made successive supersonic flights that expanded the vehicle's speed envelope from Mach 1.4, to Mach 2.87, just short of the Mach 3 goal.
Capt. Iven C. Kincheloe, Jr., joined Everest, and the two successfully completed 16 flights - 4 glide and 12 powered - between August 1954 and September 1956. During the last of these, Kincheloe attained an altitude of 126,200 feet. This first manned fight beyond 100,000 feet earned him the sobriquet "First of the Spacemen."
Following the Air Force test program, the X-2 was to be transferred to the NACA for scientific research. Before that happened, Kincheloe made several attempts to achieve a flight to Mach 3.05 but all were aborted due to engine malfunctions. Air Force officials then requested and received a two-month extension to qualify Mel Apt in the X-2, though not explicitly for a final attempt to achieve the vehicle's design Mach number.
Triple sonic man
The first man to fly three times the speed of sound was born in Buffalo, Kansas, on April 8, 1924. Apt joined the Army Air Forces in 1941 and was sent to flight training. Commissioned in February 1944, he served with the Caribbean Defense Command until June 1946. He received a Bachelor of Science degree from the University of Kansas at Lawrence in 1951 and then graduated from the Air Force Institute of Technology at Wright-Patterson Air Force Base, Ohio, with a degree in aeronautical engineering. He completed the U.S. Air Force Experimental Flight Test Pilot School at Edwards in September 1954.
Apt was well known for remaining cool under stressful situations. While flying chase for a Lockheed F-94C on a test sortie, an emergency arose when the test aircraft crash-landed on Rogers Dry Lake, trapping Capt. Richard J. Harer in the cockpit. Apt landed beside the stricken craft and rushed to Harer's aid. At great personal risk, Apt pulled Harer from the burning plane and saved his life.
In April 1955, Apt accepted an assignment as an experimental test pilot at the AFFTC Fighter Operations Branch. He served as a flight test engineer and project pilot on various test programs involving the F-100, F-101, F-102, and F-105. He also conducted extensive inertia coupling tests in the F-100C. He had 3,500 flight hours including more than 1,000 hours in jet aircraft.
Apt was assigned to the X-2 program in February 1956 and flew several chase missions in support of Kincheloe's altitude flights. Finally, in September 1956, he was offered the opportunity to fly the X-2 himself. To prepare, he studied past performance and time history data from all previous X-2 flights, spent several hours in the simulator, and was briefed by NACA stability experts. He also practiced dead-stick landings in an F-86, optimum flight path techniques in an F-100, and performed ground runs of the X-2 engine. Several times, Apt donned his pressure suit and sat in the X-2 cockpit practicing procedures and simulating failures while supervised by Bell engineers. Kincheloe briefed Apt on all details of X-2 performance and stability characteristics.
Initially, Apt was limited to a maximum speed of Mach 2.45 due to the difficulty of achieving an optimum flight profile on a first attempt. Although this restriction was later modified, he was instructed to make no effort to obtain maximum speed but rather to stay within previous limits, and to concentrate on refining techniques for achieving an optimum flight profile.
The mission was scheduled for September 27. Just before the flight, Kincheloe - who would perform chase duties - expressed his confidence in Apt's abilities. "You've got it hacked, dad," he told Apt, according to Kincheloe's biographer, James J. Haggerty Jr., in First of the Spacemen.
From victory to ashes
Preparations began in the predawn hours. Shortly after daybreak, the B-50 carried the X-2 into a clear blue sky over the Mojave Desert. After being lofted to 31,800 feet and released, Apt raced away under full power, quickly outdistancing two F-100 chase planes.
He exceeded Mach 1 at 44,000 feet and, with coaching from Kincheloe, achieved a near perfect flight profile that carried the X-2 to 72,200 feet. He nosed over, accelerating rapidly in a shallow dive. Following engine burnout, the X-2 continued to accelerate to nearly Mach 3.2.
This was no small feat. Over the course of eight earlier flights, Everest had experienced great difficulty establishing an optimum flight path. Apt managed it on his first try, and became the first man to fly more than three times the speed of sound.
Still above Mach 3 - and possibly concerned about having sufficient energy to make it back to Edwards - he began an abrupt turn back toward Rogers Dry Lake. This maneuver proved fatal as the X-2 began a series of diverging rolls and tumbled out of control. Apt's final radio transmission sounded like, "There she goes!"
He was apparently knocked unconscious for a few moments, but came to and tried to regain control of the aircraft. Unable to do so, Apt separated the escape capsule and was again knocked unconscious as it pitched down violently. By the time he again regained his senses it was too late. He attempted to bail out at extremely low altitude and was killed when the capsule impacted on the Edwards range. The airplane's fuselage and wings fell to Earth five miles away.
Today, little of the X-2 remains at the crash sites. Artifacts from both locations are now in the AFFTC Museum collection. "Part of the Museum's mission," said curator George Welch, "is to remember those who put their lives on the line in furthering the advancement of aeronautical technology, and to honor them."