20 December 2004: The 20th Fighter Squadron, Holloman Air Force Base, New Mexico, the last operational squadron in the United States Air Force flying the McDonnell Douglas F-4 Phantom II, was inactivated. The squadron’s F-4F fighters were sent to The Boneyard at Davis-Monthan Air Force Base, Tucson, Arizona.
20 December 1968: After 199 flights, NASA cancelled the X-15 hypersonic research program. A 200th flight had been scheduled, but after several delays, the decision was made to end the program. (The last actual flight attempt was 12 December 1968, but snow at several of the dry lakes used as emergency landing areas resulted in the flight being cancelled.)
There had been three X-15A rocketplanes—serial numbers 56-6670, -6671 and -6672—built by North American Aviation, Inc., Los Angeles Division. The project was sponsored by the National Advisory Committee on Aeronautics (NACA), the United States Air Force and United States Navy, with the purpose of exploring flight in the Mach 3–Mach 7 range and altitudes above 100,000 feet (30,480 meters). Design work started in 1955 and a mock-up had been completed after just 12 months.
The first flight took place 8 June 1959 with former NACA test pilot Albert Scott Crossfield in the cockpit of the Number 1 ship, 56-6670.
Over the next nine-and-a-half years, the three rocketplanes were carried aloft from Edwards Air Force Base in the high desert of southern California and Nevada by two modified Boeing B-52 Stratofortress “motherships”, NB-52A 52-003 and NB-52B 52-008. They were flown by twelve test pilots, three of whom would qualify as astronauts in the X-15, and one, Neil Alden Armstrong, who would be the first human to set foot on the surface of the Moon, 20 July 1969. One pilot, John B. (“Jack”) McKay, was seriously injured during an emergency landing at Mud Lake, Nevada, 9 November 1962, and another, Michael James Adams, was killed when the Number 3 ship, 56-6672, went into a hypersonic spin and broke up on the program’s 191st flight, 15 November 1967.
The Number 1 ship, -670, was the first and the last to fly, with its final flight taking place 24 October 1968 with test pilot Bill Dana. -670 had been carried aloft by a B-52 142 times and had made 81 free flights. It was retired to the Smithsonian Institution National Air and Space Museum, Washington, D.C.
Number 2, 56-6671, few to the highest speed, Mach 6.7, 4,250 miles per hour on its last flight, number 188. This ship had made 53 flights, with 22 taking place after it had been modified to the X-15A-2 configuration. It is in the collection of the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.
Ship number 3, 56-6672 had achieved the maximum altitude of the program, reaching 354,200 feet (107,960 meters). It was destroyed on its 65th flight, the 191st of the program.
The X-15s were built primarily of a nickel/chromium/iron alloy named Inconel X, which was both very hard and also able to maintain its strength at the very high temperatures the X-15s were subjected to by aerodynamic heating. It was extremely difficult to machine and special fabrication techniques had to be developed. Since the X-15 was built of steel rather than light weight aluminum as are most aircraft, it was a heavy machine, weighing 14,600 pounds (6,623 kilograms) empty and 34,000 pounds (15,422 kilograms) when loaded with a pilot and propellants. It was 50 feet, 9 inches (15.469 meters) long with a wing span of 22 feet, 4 inches (6.807 meters). The height, the distance between the tips of the dorsal and ventral fins, was 13 feet, 6 inches (4.115 meters). It was flown by one pilot. The airplane was powered by a single Reaction Motors XLR99-RM-1 rocket engine, burning ammonia and liquid oxygen. The XLR99 was throttleable between 28,500 and 60,000 pounds of thrust. Pumps and reaction thrusters were powered by hydrogen peroxide. The cockpit was pressurized with nitrogen.
20 December 1962: Milton Orville Thompson, a NASA test pilot assigned to the X-15 hypersonic research program, was conducting a weather check along the X-15’s planned flight path from Mud Lake, Nevada to Edwards Air Force Base in California, scheduled for later in the day. Thompson was flying a Lockheed F-104A-10-LO Starfighter, Air Force serial number 56-749, call sign NASA 749.
In his autobiography, At the Edge of Space, Thompson described the day:
“The morning of my weather flight was a classic desert winter morning. It was cold, freezing in fact, but the sky was crystal clear and there was not a hint of a breeze—a beautiful morning for a flight.”
Completing the weather reconnaissance mission, and with fuel remaining in the Starfighter’s tanks, Milt Thompson began practicing simulated X-15 approaches to the dry lake bed.
X-15 pilots used the F-104 to practice landing approaches. The two aircraft were almost the same size, and with speed brakes extended and the flaps lowered, an F-104 had almost the same lift-over-drag ratio as the X-15 in subsonic flight. Thompson’s first approach went fine and he climbed back to altitude for another practice landing.
When Milt Thompson extended the F-104’s flaps for the second simulated X-15 approach, he was at the “high key”— over Rogers Dry Lake at 35,000 feet (10,668 meters) — and supersonic. As he extended the speed brakes and lowered the flaps, NASA 749 began to roll to the left. With full aileron and rudder input, he was unable to stop the roll. Adding throttle to increase the airplane’s airspeed, he was just able to stop the roll with full opposite aileron.
Thompson found that he could maintain control as long as he stayed above 350 knots (402 miles per hour/648 kilometers per hour) but that was far too high a speed to land the airplane. He experimented with different control positions and throttle settings. He recycled the brake and flaps switches to see if he could get a response, but there was no change. He could see that the leading edge flaps were up and locked, but was unable to determine the position of the trailing edge flaps and came to the conclusion that the trailing edge flaps were lowered to different angles.
Thompson called Joe Walker, NASA’s chief test pilot, on the radio and explained the situation:
“I told him the symptoms of my problem and he decided that I had a split trailing edge flap situation with one down and one up.
“He suggested I recycle the flap lever to the up position to attempt to get both flaps up and locked. I had already tried that, but I gave it another try. Joe asked if I had cycled the flap lever from the up to the takeoff position and then back again. I said no. I had only cycled the flap lever from the up position to a position just below it and then back to the up position. Joe suggested we try it his way. I moved the flap lever from the up position all the way to the takeoff position and then back to the up position. As soon as I moved the lever to the takeoff position, I knew I had done the wrong thing.
“The airplane started rolling again, but this time I could not stop it. The roll rate quickly built up to the point that I was almost doing snap rolls. Simultaneously, the nose of the airplane started down. I was soon doing vertical rolls as the airspeed began rapidly increasing. I knew I had to get out quick because I did not want to eject supersonic and I was already passing through 0.9 Mach. I let go of the stick and reached for the ejection handle. I bent my head forward to see the handle and then I pulled it. Things were a blur from that point on.”
—At the Edge of Space: The X-15 Flight Program, by Milton O. Thompson, Smithsonian Institution Press, Washington and London, 1992. Chapter 5 at Pages 119–120.
As Thompson descended by parachute he watched the F-104 hit the ground and explode in the bombing range on the east side of Rogers Dry Lake. He wrote, “It was only 7:30 a.m. and still a beautiful morning.”
Rank and organization: Technical Sergeant, U.S. Army Air Corps. 358th Bomber Squadron, 303d Bomber Group.
Place and date: Over Bremen, Germany, December 20, 1943.
Entered service at: Rochester, New York. Born: July 29, 1923, Lyndonville, New York.
G.O. No.: 73, September 6, 1944.
For conspicuous gallantry in action against the enemy above and beyond the call of duty while serving as a radio operator-air gunner on a heavy bombardment aircraft in a mission over Bremen, Germany, on 20 December 1943. After bombing the target, the aircraft in which T/Sgt. Vosler was serving was severely damaged by antiaircraft fire, forced out of formation, and immediately subjected to repeated vicious attacks by enemy fighters. Early in the engagement a 20-mm. cannon shell exploded in the radio compartment, painfully wounding T/Sgt. Vosler in the legs and thighs. At about the same time a direct hit on the tail of the ship seriously wounded the tail gunner and rendered the tail guns inoperative. Realizing the great need for firepower in protecting the vulnerable tail of the ship, T/Sgt. Vosler, with grim determination, kept up a steady stream of deadly fire. Shortly thereafter another 20-mm. enemy shell exploded, wounding T/Sgt. Vosler in the chest and about the face. Pieces of metal lodged in both eyes, impairing his vision to such an extent that he could only distinguish blurred shapes. Displaying remarkable tenacity and courage, he kept firing his guns and declined to take first-aid treatment. The radio equipment had been rendered inoperative during the battle, and when the pilot announced that he would have to ditch, although unable to see and working entirely by touch, T/Sgt. Vosler finally got the set operating and sent out distress signals despite several lapses into unconsciousness. When the ship ditched, T/Sgt. Vosler managed to get out on the wing by himself and hold the wounded tail gunner from slipping off until the other crewmembers could help them into the dinghy. T/Sgt. Vosler’s actions on this occasion were an inspiration to all serving with him. The extraordinary courage, coolness, and skill he displayed in the face of great odds, when handicapped by injuries that would have incapacitated the average crew member, were outstanding.
Technical Sergeant Vosler was the third of just four enlisted airmen two be awarded the Medal of Honor during World War II. After recuperating from his wounds, Vosler was discharged from the Army Air Corps. He then worked for the Veterans Administration for thirty years. Forrest L Vosler died in 1992 at the age of 68 years.
The Boeing B-17F Flying Fortress was a four-engine heavy bomber operated by a flight crew of ten. It was 74 feet, 9 inches (22.784 meters) long with a wingspan of 103 feet, 9.375 inches (31.633 meters) and an overall height of 19 feet, 1 inch (5.187 meters). Its empty weight was 34,000 pounds (15,422 kilograms), 40,437 pounds (18,342 kilograms) loaded, and the maximum takeoff weight was 56,500 pounds (25,628 kilograms). The airplane was powered by four air-cooled 1,823-cubic-inch-displacement (29.88 liters) Wright Cyclone R-1820-97 turbocharged 9-cylinder radial engines, producing 1,200 horsepower for takeoff and 1,000 horsepower at 25,000 feet (7,620 meters). War Emergency Power was 1,380 horsepower. The B-17F had a cruising speed of 200 miles per hour (322 kilometers per hour). The maximum speed was 299 miles per hour (481 kilometers per hour) at 25,000 feet, though with War Emergency Power, the bomber could reach 325 miles per hour (523 kilometers per hour) at 25,000 feet (7,620 meters) for short periods. The service ceiling was 37,500 feet (11,430 meters). With a normal fuel load of 2,520 gallons (9,540 liters) the B-17F had a maximum range of 2,880 miles (4,635 kilometers). Carrying a 6,000 pound (2,722 kilogram) bomb load, the range was 1,300 miles (2,092 kilometers).
The B-17F Flying Fortress was armed with up to 13 Browning M2 .50-caliber machine guns. Power turrets mounting two guns each were located at the dorsal and ventral positions. The maximum bomb load was 20,800 pounds over very short ranges. Normally, 4,000–6,000 pounds (1,815–2,722 kilograms) were carried. The internal bomb bay could be loaded with a maximum of eight 1,600 pound (725.75 kilogram) bombs. Two external bomb racks mounted under the wings between the fuselage and the inboard engines could carry one 4,000 pound (1,814.4 kilogram) bomb, each, though this option was rarely used.
The B-17 Flying Fortress was in production from 1936 to 1945. 12,731 B-17s were built by Boeing, Douglas Aircraft Company and Lockheed-Vega. (The manufacturer codes -BO, -DL and -VE follows the Block Number in each airplane’s type designation.) 3,405 of the total were B-17Fs, with 2,000 built by Boeing, 605 by Douglas and 500 by Lockheed-Vega.
Only three B-17F Flying Fortresses remain in existence.
19 December 1972: At 2:25 p.m. EST—12 days, 13 hours, 51 minutes, 59 seconds after departing the Kennedy Space Center at Cape Canaveral, Florida—the Apollo 17 command module America (CM-112) returned to Earth, splashing down in the South Pacific Ocean, approximately 350 miles (563 kilometers) southeast of Samoa. The three 83 foot, 6 inch diameter (25.451 meters) ring sail main parachutes had deployed at an altitude of 10,500 feet (3,200 meters) and slowed the capsule to 22 miles per hour (35.4 kilometers per hour) before it hit the ocean’s surface.
The landing had a high degree of accuracy, coming within 4.0 miles (6.44 kilometers) of the recovery ship, the aircraft carrier USS Ticonderoga (CVS-14).
The flight crew was picked up by a Sikorsky SH-3G Sea King helicopter, Bu. No. 149930, of HC-1, and transported to Ticonderoga. The three astronauts, Eugene A. Cernan, Ronald A. Evans and Harrison H. Schmitt, stepped aboard the aircraft carrier 52 minutes after splashdown.
The splashdown of Apollo 17 brought to an end the era of manned exploration of the Moon which had begun just 3 years, 3 days, 5 hours, 52 minutes, 59 seconds earlier with the launch of Apollo 11.
Just 12 men have set foot on the Moon. In 42 years, no human has returned.