10 March 1948: National Advisory Committee for Aeronautics (NACA) chief test pilot Herbert Henry (“Herb”) Hoover became the first civilian pilot to exceed the Speed of Sound when he flew a Bell X-1 supersonic research rocketplane near Muroc Air Force Base (Edwards AFB after 1949) in the high desert of southern California.

Hoover was flying the second of the three X-1s, serial number 46-063. Dropped from a B-29 “mother ship” on a stability and loads test, Hoover climbed to 42,000 feet (12,802 meters) while using three chambers of the rocketplane’s Reaction Motors XLR11-RM-3 engine. At 0.93 Mach (613.614 miles per hour/987.516 kilometers per hour), he fired the fourth chamber and accelerated to Mach 1.065 (702.687 miles per hour/1,130.865 kilometers per hour).

Hoover glided to a landing on Rogers Dry Lake. The rocketplane’s nose wheel would not extend, so Hoover held the nose up as long as possible before it settled onto the hard sand surface. 46-063 suffered minor damage.

This was the seventy-second flight of the X-1 series.

The 4 March 1948 flight Hoover’s eleventh in an X-1. Hoover had been the first NACA pilot to fly an X-1, having made a glide flight 21 October 1947. He made a total of fourteen X-1 flights before moving on to other flight test programs.

For this flight Herbert H. Hoover was awarded the Octave Chanute Award by the Institute of Aeronautical Sciences for “contributions to the application of flight test procedures to basic research in aerodynamics, and the development of methods for scientific study of transonic flight.” The award was presented at the Hotel Ambassador, in Los Angeles, California, 16 July 1948, by John Knudsen (“Jack”) Northrop, founder of the Northrop Corporation. Hoover was the initial recipient Air Force Association’s David C. Schilling Award, then known as the Flight Trophy, also awarded in 1948. In 1949, he was awarded the Air Medal by the United States Air Force, “for meritorious achievement while participating in aerial flight on March 10, 1948.” The medal was presented by President Harry S. Truman.

Herbert Henry Hoover was born 18 May 1912 at Knoxville, Tennessee. He was the  son of Benjamin Roscoe Hoover, railway conductor, and Zella Mae Edington Hoover. He attended Central High School in Knoxville, graduating in 1929.

In 1930, Hoover was employed as a civil engineer’s assistant. He then attended the University of Tennessee, graduating from the College of Engineering, 24 August 1934, with a bachelors degree in mechanical engineering.

Joining the United States Army Air Corps, Hoover was trained as a pilot at Randolph and Kelly Fields, San Antonio, Texas. Completing training, he was commissioned as a second lieutenant in the Air Corps Reserve and assigned to Mitchel Field, Long Island, New York.

Released from active duty in 1937 after three years of service, Hoover was employed by the Standard Oil Company as a pilot, flying in South America.

After returning to the United States, on 16 December 1940, Hoover became an experimental test pilot for the National Advisory Committee for Aeronautics at the NACA Langley Memorial Aeronautical Laboratory, Hampton, Virginia.

Hoover registered for Selective Service (conscription), 4 April 1942. On his draft registration card, he was described as 5 feet, 7 inches (170 centimeters) tall, 175 pounds (79 kilograms, with blond hair, gray eyes, and a light complexion.

On 29 August 1942, Hoover married Miss Ruth Anadda Rhyne at the Stanley Presbyterian Church, River Bend, North Carolina. The ceremony was presided over by Rev. R.H. Ratchford. They would have two children, Anadda Susan Hoover and Herbert Henry (“Hank”) Hoover, Jr.

Experienced at flying in bad weather, Hoover volunteered to fly the Lockheed XC-35 Supercharged Cabin Transport Airplane, 36-353, the first airplane to be built with a pressurized cabin, through thunderstorms for weather research.

In July 1943, while flying a Curtiss SB2C Helldiver on an instrument calibration flight, Hoover was badly injured when the airplane’s canopy came loose and struck him in the head. He was able to safely return to Langley.

A 1948 Newport News, Virginia, newspaper article described the incident:

     In illustrating the infrequency of mishaps in test flights, Hoover recalls that he was the principal in the first accident involving a NACA test pilot. This incidentally was his only air accident, and occurred in July 1943, while he was calibrating 1,700 pounds [771 kilograms] of instruments to be used in flight instrument investigations of the Navy Helldiver.

     The canopy over the cockpit of the Helldiver tore loose and as it fluttered away, an edge of the structure smashed through Hoover’s helmet and goggles. He found his sight blurred by blood streaming from  his forehead. Although in pain and almost blinded, Hoover kept his seat in the now open airplane, turned back to Langley and put his ship into a maneuver that would attract attention. The men on the ground instantly understood that something was wrong and cleared the afield of other aircraft, and Hoover brought the Helldiver to a safe landing.

—Daily Press, Vol. LIII, No. 188, 15 July 1948, at Page 8, Columns 1 and 2

On another occasion, while firing a rocket-propelled model during a 0.7 Mach dive, the rocket exploded and seriously damaged Hoover’s North American Aviation P-51 Mustang. The Mustang’s coolant tank was punctured, but he was able to make a successful forced landing.

Hoover was appointed NACA’s chief test pilot. He was assigned to the NACA Muroc Flight Test Unit at Muroc Air Force Base, California, to begin NACA flight testing of the Bell X-1. He made his first flight in the X-1 one week after Captain Charles Elwood (“Chuck”) Yeager broke the “sound barrier” flying the number one Bell X-1, 46-062, 14 October 1947.

Herb Hoover was killed when the North American Aviation B-45A-1-NA Tornado, 47-021, “NACA 121,” suffered a structural failure in flight near Burrowsville, Virginia 14 August 1952. It is believed that he struck the aircraft, or parts of the aircraft, during ejection. His body was found with his parachute unopened, but with his hand on the rip cord’s “D”-ring. The airplane’s copilot, John A. Harper, survived with minor injuries.

The St. Louis Post-Dispatch reported:

PIONEER JET FLYER KILLED IN PARACHUTING

Herbert H. Hoover and Colleague Testing B-45 Bomber When It Catches Fire

     BURROWSVILLE, Va., Aug. 15 (AP)—One of the pioneers of faster than sound flight fell to his death yesterday from a crippled B-45 jet bomber.

He was test pilot Herbert H. Hoover, the first man to fly the Bell X-1, and experimental prototype of the present day supersonic aircraft.¹

The heavy four-jet aircraft caught fire over this south-eastern Virginia community and Hoover and a companion, J.A. Harper bailed out.

Harper landed safe, except for a bruised shoulder. Searchers found the crumpled body of Hoover, his hand clutching the ripcord of his unopened parachute.

Both men were employed by the National Advisory Committee for Aeronautics Laboratory at Langley Field, Va., for which they were testing aircraft.

     Officials of the NACA said the crash was caused by the failure of the outboard panel of the right wing of the bomber. A spokesman, asked about a published report that the plane exploded, said, “there was no explosion.”

     Officials who had talked with Harper said an overload was imposed during a maneuver to check research instruments and as a result the panel failed.

     They said that there was afire following the wing panel’s collapse, but “it is not believed that the fire had any material effect on the accident.”

     Hoover was the first pilot to exceed the speed of sound in an NACA aircraft and the second to break the sound barrier in any plane.

     He had made more than a dozen flights in all. He received the Air Force Association award for 1948 for that year’s most notable achievement in  flight contributing to the nation’s air defense.

     Hoover served in the Army Air Corps from 1934 to 1937. He was a member of the first active long-range reconnaissance unit, the Eighteenth Reconnaissance Squadron, then stationed at Mitchel Field, N.Y.

—St. Louis Post Dispatch,  Vol. 104, No. 323, 15 August 1952, Page 39, Column 4

In eighteen years of flying Herbert Henry Hoover had flown more than 100 aircraft types. He was the third NACA test pilot to be killed.² His remains were interred at the Peninsula Memorial Park, Newport News, Virginia.

The Bell XS-1, later re-designated X-1, was the first of a series of rocket-powered research airplanes which included the Douglas D-558-II Skyrocket, the Bell X-2, and the North American Aviation X-15, which were flown by the U.S. Air Force, U.S. Navy, NACA and its successor, NASA, at Edwards Air Force Base to explore supersonic and hypersonic flight and at altitudes to and beyond the limits of Earth’s atmosphere.

The X-1 has an ogive nose, similar to the shape of a .50-caliber machine gun bullet, and has straight wings and tail surfaces. It is 30 feet, 10.98 inches (9.423 meters) long with a wing span of 28.00 feet (8.534 meters) and overall height of 10 feet, 10.20 inches (3.307 meters).

46-062 was built with a thin 8% aspect ratio wing, while 46-063 had a 10% thick wing. The wings were tapered, having a root chord of 6 feet, 2.2 inches (1.885 meters) and tip chord of 3 feet, 1.1 inches (0.942 meters), resulting in a total area of 130 square feet (12.1 square meters). The wings have an angle of incidence of 2.5° with -1.0° twist and 0° dihedral. The leading edges are swept aft 5.05°.

The horizontal stabilizer has a span of 11.4 feet (3.475 meters) and an area of 26.0 square feet (2.42 square meters). 062’s stabilizer has an aspect ratio of 6%, and 063’s, 5%.

The fuselage cross section is circular. At its widest point, the diameter of the X-1 fuselage is 4 feet, 7 inches (1.397 meters).

46-062 had an empty weight is 6,784.9 pounds (3,077.6 kilograms), but loaded with propellant, oxidizer and its pilot with his equipment, the weight increased to 13,034 pounds (5,912 kilograms).

The X-1 was designed to withstand an ultimate structural load of 18g.

The X-1 was powered by a four-chamber Reaction Motors, Inc., 6000C4 (XLR11-RM-3 ) rocket engine which produced 6,000 pounds of thrust (26,689 Newtons). This engine burned a 75/25 mixture of ethyl alcohol and water with liquid oxygen. Fuel capacity is 293 gallons (1,109 liters) of water/alcohol and 311 gallons (1,177 liters) of liquid oxygen. The fuel system was pressurized by nitrogen at 1,500 pounds per square inch (103.4 Bar).

The X-1 was usually dropped from the B-29 flying at 30,000 feet (9,144 meters) and 345 miles per hour (555 kilometers per hour). It fell as much as 1,000 feet (305 meters) before beginning to climb under its own power.

The X-1’s performance was limited by its fuel capacity. Flying at 50,000 feet (15,240 meters), it could reach 916 miles per hour (1,474 kilometers per hour), but at 70,000 feet (21,336 meters) the maximum speed that could be reached was 898 miles per hour (1,445 kilometers per hour). During a maximum climb, fuel would be exhausted as the X-1 reached 74,800 feet (2,799 meters). The absolute ceiling is 87,750 feet (26,746 meters).

The X-1 had a minimum landing speed of 135 miles per hour (217 kilometers per hour) using 60% flaps.

There were 157 flights with the three X-1 rocket planes. The number one ship, 46-062, Glamorous Glennis, made 78 flights. On 26 March 1948, with Chuck Yeager again in the cockpit, it reached reached Mach 1.45 (957 miles per hour/1,540 kilometers per hour) at 71,900 feet (21,915 meters).

The second X-1, 46-063, was later modified to the X-1E. It is on display at the NASA Dryden Research Center at Edwards Air Force Base. Glamorous Glennis is on display at the Smithsonian Institution National Air and Space Museum, next to Charles A. Lindbergh’s Spirit of St. Louis.

The third X-1, 46-064, made just one glide flight before it was destroyed 9 November 1951 in an accidental explosion.

¹ This is incorrect. The first pilot to fly the Bell X-1 was Bell Aircraft Corporation Senior Experimental Test Pilot Jack Valentine Woolams. Please see This Day in Aviation at https://www.thisdayinaviation.com/19-january-1946/ Herb Hoover had been the first NACA pilot to fly an X-1.

² The first was Howard Clifton (“Tick”) Lilly, when the compressor section of a Douglas D-558-I Skystreak exploded 3 May 1948. Please see TDiA at https://www.thisdayinaviation.com/3-may-1948/

© 2025, Bryan R. Swopes