posted 12-29-2024 06:11 AM               

Space Cover 786: Birth of the X-15

The cover above was postmarked nearly 70 years ago at Edwards AFB on January 17, 1955, the date that the US Air Force announced that their (along with NACA's and the Navy's) new hypersonic rocketplane would be known as the X-15. The next day, aerospace contractors attended a bidder's conference to begin their bids for the plane.

By 1954 it had become apparent to the Air Force, Navy, and NACA that they needed another rocketplane that could go beyond the projected three-times-the-speed-of-sound (Mach 3) and altitudes of 20 miles of the yet unrealized X-2. Concepts ranged from a Mach 4.5 X-2 supplemented with solid rocket motors to a Mach 10 very-high-tech new rocketplane. In March 1954 NACA came up with a concept that served as the starting point for the X-15, shown below.

This would be a Mach 7 rocketplane, using three engines derived from the Hermes missile, launched from a B36 bomber plane. As 1954 progressed, further studies showed that the three Hermes engines were insufficient (albeit simpler) and that a more powerful throttleable engine was needed. And all three organizations gelled in their commitment to such a new rocketplane enough to make the announcement mentioned above and ask for bids from industry in January 1955.

The rest of 1955 was consumed with the competition for the X-15 contract between the Bell, Douglas, North American, and Republic aircraft companies. North American was selected in August 1955 but retracted its bid before award. Some further negotiations took place, and North American signed a letter contract to begin the X-15 on December 5, 1955.

The X-15 made its first powered flight on September 17, 1959, as shown on the Goldcraft cachet cover above. As you may see from the cachet art, it carried two rocket engines. The big throttleable engine (known as the XLR-99) wasn't ready yet, so flight testing proceeded with two smaller XLR-11 engines scavenged from the prior X-1 and D-558-II programs. Even with the smaller interim engines, by October 1960, the X-15 had eclipsed the prior X-2 program records. And with the arrival of the XLR-99 engine in November 1960, the X-15 powered to the records we are all familiar with today — over Mach 6 and over 60 miles altitude.

posted 12-30-2024 12:44 PM               

Those of us who are fascinated by the X-15 and collect material about it, should be able to name all twelve pilots without much trouble.

But maybe a pilot who was one of the first three selected to fly the X-15 and was designated the X-15 Project Test Pilot, may not be known or remembered by too many.

He was Captain Iven Kincheloe, USAF, who would have certainly flown many X-15 flights. Kincheloe was a Korean War ace with five enemy kills and later a test pilot at Edwards AFB where he flew the X-2 rocket plane. In 1956 he became the first pilot to exceed 100,000 feet in altitude. But the next flight ended the X-2 Program, when the X-2 tumbled out of control, resulting in the death of Mel Apt.

But the ill-fated X-2 led the way for the X-15 and Kincheloe was one of the first three pilots to be selected to fly the X-15. He perhaps would have been the first.

But fate was cruel to Kincheloe, as he was killed in the crash of an F-104 at Edwards before the X-15 flew. His back-up, Bob White, then took his place and flew many X-15 flights.

This photo pictures Kincheloe in the middle, with the first man to walk on the moon on the left, and Bob White on the right.

posted 12-31-2024 06:42 PM               

Hard to believe that hundreds of test pilots have lost their lives here in the States since the late 1940's, with most during the 50's where it was estimated that a research (test) pilot died almost every week. Most were military and contractor pilots during that pioneering decade (1960's too) due to the early stages of aircraft jet engine and rocketplane powered technology development.

As Bob said, Major Clifton Williams (USMC) had been assigned LMP for Apollo 12, but after his death in Oct. 1967, was replaced by Alan Bean in becoming the fourth lunar surface explorer in Nov. 1969.