Some have suggested that the force was with Rutan in 1975, before the movie Star Wars spread it to the rest of the world. The film was released in 1977, the first full year the VariEze plans were sold, and many see a resemblance between the dashing X-fighter spacecraft that George Lucas created for the screen and the otherworldly VariEzes that were proliferating at small airports across the country. The VariEzes don’t have the “X” configuration and aren’t propelled by whatever exotic method the X-fighters use, but they do have one thing in common with the movie-star airplanes: Thirty-four years later, they still look like the future. (Read our recent interview with Rutan.)
A Little Extra Oomph
When the u.s. air force and the National Advisory Committee for Aeronautics started exploring high-speed flight with the Bell XS-1 in 1947, off came the lid of a Pandora’s Box of aerodynamic woes that had only been hinted at as piston-engine aircraft approached transonic speeds. In October, shortly before achieving Mach 1.06, Chuck Yeager found that as he neared the speed of sound, the XS-1 would no longer respond to control inputs. “I pulled back on the control column,” he told an interviewer for the PBS series “NOVA” in 1997. “Nothing happened. The airplane just went the way it was headed.” Like the gremlin that roamed the wing in “The Twilight Zone” episode “Nightmare at 20,000 Feet,” a shock wave had taken up residence along the horizontal stabilizer, preventing the two small elevators on the stabilizer’s trailing edge from fully responding to pilot input.
Yeager and the rest of the team thought that if the entire horizontal stabilizer rather than just the elevators could be made to move up and down, the “all-moving tail” might be able to win the arm wrestle with the shock wave. Thanks to the NACA design team at Virginia’s Langley Aeronautical Laboratory, the XS-1 had been equipped with just such an adjustable stabilizer — a sort of gigantic trim tab. The XS-1 team set to jury-rigging a fix. “Being a mechanic, all we did was squirt 3-in-1 oil on it and run it up and down, up and down, until it worked,” Yeager said.
On October 14, after the B-29 mothership released the XS-1, the bullet-shaped aircraft reached 94 percent of the speed of sound at 42,000 feet. “I just cranked the leading edge up on the horizontal stabilizer to keep the nose down,” Yeager said. “All the buffeting smoothed out, because the supersonic flow went over the whole airplane.” Then a boom echoed over the high desert: The XS-1 had exceeded the speed of sound.
And that’s what it took to crack Mach 1 without the inconvenience of a catastrophic structural failure. Today, all supersonic aircraft wear all-moving tails.