Sixty-one years ago today, the USN/Douglas D-558-II Skyrocket soared to an unofficial world record altitude of 83,235 feet. The Skyrocket’s record altitude mission was piloted by USMC test pilot and World War II triple-ace Lieutenant Colonel Marion E. Carl.
The D-558-II was a United States Navy (USN) X-aircraft and first flew in February of 1948. It was contemporaneous with the USAF/Bell XS-1. The aircraft measured 42 feet in length with a wing span of 25 feet. Maximum take-off weight was 15,266 pounds. Douglas manufactured a trio of D-558-II aircraft (Bureau No.’s 37973, 37974 and 37975).
The original version of the swept-wing D-558-II had both rocket and turbojet propulsion. The latter system provided a ground take-off capability. However, like other early X-aircraft such as the XS-1, X-1A, X-2 and X-15), the D-558-II achieved maximum performance through the use of a mothership and rocket power alone.
On Friday, 21 August 1953, D-558-II (Bureau No. 37974; NACA 144) was carried to a drop altitude of approximately 30,000 feet over Edwards Air Force Base by a USN P2B-1S launch aircraft. Following drop, Carl fired his LR-8 rocket motor and executed a pull-up in an effort to extract maximum altitude from the D-558-II. Carl hit a maximum Mach number of 1.728 and exceeded the existing altitude by about 3,800 feet.
Flying the D-558-II to altitudes beyond 65,000 feet required Carl to wear a full-pressure suit. The versions available to test pilots in the early 1950′s were crude by today’s standards. They were extremely uncomfortable and very confining. The pilot had to use reverse breathing to supply adequate oxygen to the lungs.
Reverse breathing involves the inhalation of air under pressure wherein oxygen is forced into the lungs by simply opening the mouth. One then has to make a conscious effort to exhale against that pressure in order rid the lungs of carbon dioxide. This unnatural breathing process had to be practiced by a pilot until it became second nature.
Flying the D-558-II (and other 1950′s high-speed research aircraft such as the X-1, X-1A and X-2) to extreme altitude was a sporty proposition. These aircraft exhibited disturbing lateral-directional control characteristics at low dynamic pressure. None of the early X-planes were configured with a 3-axis reaction control system. Control had to be maintained solely by aerodynamic means.
Marion Carl’s altitude mark in the D-558-II would stand until September of 1956 when USAF Captain Iven Kincheloe flew the USAF/Bell X-2 to an altitude of 126,200 feet. Today, the record-setting D-558-II (NACA 144) is displayed at the National Air and Space Museum in our Nation’s capital.
Marion Carl went on to serve his country until he retired from the Marine Corps in 1973 after having attained the rank of Major General. Sadly, Carl was shot to death in 1998 at the age of 82 as he defended his wife Edna from a home invader. A true American hero, Marion E. Carl was buried with full military honors at Arlington National Cemetery.