Scott Crossfield claimed that he “just dropped the hint to the Navy that wouldn’t it be great if they could whip Yeager’s ass and beat him to Mach 2!”
The six Douglas D-558 research aircraft, built as two distinct types, were the US Navy’s contribution to the supersonic X-Plane program. In the late 1940s wind tunnels could not replicate these speeds, so pilots had to risk their lives in experimental aircraft with phenomenal performance.
Although delayed by their innovative but troublesome powerplants and limited by the cost of their air-launched sorties, the D-558s went well beyond their original Mach 1 speed objective.
In Scott Crossfield’s hands in fact, the D-558-2 became the first aircraft to break Mach 2.
As explained by Peter E. Davies in his book Douglas D-558, Dr Hugh Dryden at NACA was content to let the USAF reach the speed of Mach 2 if they wished. However, Crossfield and Walter Williams persuaded Dr Dryden that there would be scientific benefits in pushing the D-558-2, with its improved engine, to the limits of its performance. Crossfield later claimed that he “just dropped the hint to the Navy that wouldn’t it be great if they could whip Yeager’s ass and beat him to Mach 2!” With further persuasion from Rear Admiral Apollo Soucek of the Bureau of Aeronautics and Marion Carl, the Pentagon agreed to a one-off Navy attempt at Mach 2 before surrendering the task to Chuck Yeager.
On Sep. 17, 1953, Crossfield began test flights in D-558-2 aircraft featuring several modifications. The “X-plane” in fact had the nozzle extensions installed and a tank regulator in the cockpit so that Crossfield could increase pressures in the four rocket chambers. The two modifications increased total thrust to almost 9,000 lb. Flights continued through October and November as stability and aerodynamic load tests, but with gradually increasing maximum speeds. In mid-November NACA plotted a flight profile in which Crossfield would have to follow a very precise climb, speed, and angle-of-attack after launch. After the “push-over” he would enter a shallow dive and reach Mach 2.
NACA 144 (BuNo 37974) was carefully prepared with waxed finish, sealed panels, and a prolonged “cold soak” after the LOX was loaded to allow the liquid gas to settle and be topped up, both on the ground and from the carrier aircraft’s top-up system when airborne. The process also added seven seconds to the burn time. At the tail end, the stainless-steel propellant vent tubes were replaced with lighter aluminum versions, bent so that they would burn off in the rocket efflux and save a little weight. On Nov. 20, 1953 the P2B-1S bomber (the US Navy version of the Boeing B-29) and its load took off with NACA pilot Stanley Butchart at the bomber’s controls. Butchart was a former World War II Naval Aviator in a torpedo-bomber squadron with future US president George Bush. He spent 25 years in research aviation, flying the D-558-1 on 12 occasions, and he was the High-Speed Flight Station’s main multi-engined pilot, launching hundreds of experimental aircraft from B-29s and other carrier aircraft for six years.
At 10,000 ft altitude Crossfield prepared to launch, and on release he ignited all four rocket chambers and climbed to 72,178 ft before pushing over into level flight in the plan and accelerating for another 45 seconds until the rocket fuel was exhausted. At that point he was surprised to notice Mach 2.04 on his Mach meter. He had become the world’s fastest man and the D-558-2 had at last reached Mach 2, far beyond its maximum design speed, and the USN held the records for both speed and altitude.
Three weeks later, Yeager boarded the modified Bell X-1A, determined to beat Crossfield’s record substantially in a contractor flight effort unofficially called “Operation NACA Weep”. Yeager’s team estimated that the X-1A’s horizontal tail would be effective up to Mach 2.3 at 72,000ft, but its instability problems had already been seen at Mach 1.8. On Dec. 12, Yeager launched at 30,500 ft, accelerated to Mach 2 at 76,000 ft, pushed over and entered a shallow dive that reached Mach 2.4 before all the flying controls lost effect. The aircraft tumbled, completely out of control in a wild spin for 50,000 ft, battering him into near unconsciousness before he could recover it. Fortunately, the X-1A’s immensely tough airframe remained intact and Yeager also survived, commenting, “Boy, I’m not gonna do that again.” It was his last rocket-plane flight.
Douglas D-558 is published by Osprey Publishing and is available to order here.
Photo credit: NASA