Chuck Yeager broke the sound barrier in 1947 in the rocket-powered Bell X-1 Glamorous Glennis. Three years earlier, a British Supermarine Spitfire Mark XI had already come within 11 percent of doing the same thing with a piston engine and a propeller. In 1944, RAF test pilot J.R. Tobin dove his Spitfire to 606 miles per hour — Mach 0.89. In a follow-up test, Anthony F. Martindale pushed the same airframe to 620 mph in a 45-degree dive. The propeller tore off, the tail-heavy aircraft climbed automatically, and Martindale woke at 40,000 feet to glide home.
Supermarine Spitfire Almost Did the Impossible: Broke the Sound Barrier
You know already that Chuck Yeager broke the sound barrier in 1947. Yeager hopped aboard the rocket-powered Bell X-1 named Glamorous Glennis, and he reached Mach 1.05. Yeager was thrilled even though he maintained his icy demeanor.
The United States basked in the glory of this heady feat. The Americans loved his confidence and grace under pressure.
Others realized that the plus-MACH 1 flight would be extremely difficult for airplanes before 1947.
Many pilots tried to break the sound barrier, but their airplanes could not do the job. The engines were not powerful enough, and the aircraft’s overall design could not deliver the goods.
The United Kingdom had a Hand in Super-Fast flight
However, it is a little-known fact that one conventional fighter plane paved the way to the Yeager flight.
The British Supermarine Spitfire was a force of nature that helped engineers and technicians realize that maybe the United Kingdom could be the first to break the sound barrier and beat the Americans.
The Spitfire was instrumental in fighting the Nazis during the Battle of Britain. Pilots were courageous and knew how to push the airplane beyond its abilities and shoot down enemy pilots at will to save the country.
Hitting Four Hundred Miles Per Hour Was Easy
The BBC has more on how the Spitfire’s history was marked by high-speed flight. The airplane could knife through the air at 400 miles per hour. There was a “Rolls-Royce Merlin engine and the four-bladed propeller that helped generate extra thrust,” the news outlet recalled.
P-51D Mustang Fighter. Image taken by National Security Journal Editor Harry J. Kazianis on July 19, 2025.
The Recon Spitfires Were Even Faster
The Spitfires that were outfitted for photo-reconnaissance were even faster without the weapons systems. When these stripped-down airplanes flew, British pilots told their superiors that perhaps this would be the one that could eclipse the magical threshold of plus-MACH 1.
Getting Close to MACH 1
Stephen Dowling at the BBC discovered a book that revealed how the British made the Spitfire even faster. Dowling read a tale from Eric ‘Winkle’ Brown’s book Wings on My Sleeve. Brown recalled how the Spitfire could approach 600 miles per hour. This was getting close to the magical speed.
Brown told the story about test pilot J.R. Tobin, who maneuvered his Mark XI Spitfire into a 45-degree dive. The speed was 606 miles per hour or MACH 0.89. The Spitfire had never flown that fast.
One Accident During High-speed Testing Could Have Been Fatal
The British were excited and planned to keep the Spitfire speed program in effect. By 1944, they were ready to test again with a different pilot. Anthony F. Martindale flew the same plane and dove downward. He reached 620 miles per hour, but the propeller ripped apart. Yikes, this was a frightening experience, and maybe the British were not meant to push the Spitfire that hard.
What Happened Next?
As Dowling described, “Martindale was saved by simple physics. With the heavy propellers wrenched off, the aircraft was now tail-heavy, and the change in center of gravity forced it to climb out of the dive at high speed. Martindale was knocked unconscious from the stress of the climb and woke to find his aircraft flying at 40,000 feet. Somehow, he managed to glide the aircraft back to his base and emerged unscathed.”
The Propeller Broke Apart
The test pilots had shown that the “subsonic flow of the wing,” as Rod Irvine, of the Royal Aeronautical Society, explained, could push a plane toward the sound barrier, but it was dangerous when the propeller was struggling.
“It starts to flick around all over the place, and it feels like the aircraft is starting to shake itself to bits because you get this fundamental change in the aerodynamics,” Irvine told the BBC.
Another problem with the piston engine on the Spitfire is that it could only run at a limited number of revolutions per minute. But the Spitfire had variable-pitch propellers that helped it achieve the blinding velocity (for those days) during World War Two.
P-51D Mustang from U.S. Air Force Museum. Image taken by National Security Journal 7/19/2025.
P-51D Mustang Fighter NSJ Photo. Image taken on 7/19/2025.
The Spitfire Left a Speedy Legacy
The Spitfire never reached MACH 1, but it could generate a surprising amount of speed. The airplane was not only a combat stalwart but also brought the sound barrier within reach of Yeager and American jet designers.
The British lost the race but were trailblazers who should be credited for building great engines. Not to mention their Royal Air Force test pilots had the right stuff. This likely made Yeager even more determined to be first.
My Interview With Chuck Yeager
I once interviewed Yeager when I was a TV reporter. He was crusty back then and camera-shy. I asked the most obvious and cliché question (sometimes those get the best answers). “How did it feel to fly that fast?” He replied in a grunt, “I was just doing my job. Next dumb question.”
He may not have known that the Spitfire could go that fast and that it came so close to MACH 1. So the British can claim a partial victory, and that is just fine for the history books to tease out facts by delivering an unknown story that added to the annals of supersonic flight.
About the Author: Brent M. Eastwood, PhD
Author of now over 3,500 articles on defense issues, Brent M. Eastwood, PhD, is the author of Don’t Turn Your Back On the World: A Conservative Foreign Policy and Humans, Machines, and Data: Future Trends in Warfare, plus two other books. Brent was the founder and CEO of a tech firm that predicted world events using artificial intelligence. He served as a legislative fellow for US Senator Tim Scott and advised the senator on defense and foreign policy issues. He has taught at American University, George Washington University, and George Mason University. Brent is a former US Army Infantry officer. He can be followed on X @BMEastwood.
