The end of an era

This week sees the 40th anniversary of the end of one of aerospace’s most significant periods.

September 23rd 1975 saw Bill Dana bring the X-24B research plane in for a landing on the main runway at Edwards AFB in California, thus marking the end of the last manned rocket flight at Edwards, a final act in an illustrious period that began in 1944, back when Edwards was still known as Muroc Army Airfield.

Back then, Muroc was an isolated and desolate facility in the high desert, mainly used for bombing practice. But it’s isolation and the huge, flat expanse of Rodgers dry lake made it the ideal location for Northrop to test their rocket powered flying-wing prototype the MX-334. On July 5th 1944 Harry Crosby lit the MX-334’s XCALR-200 engine making the first flight by an American rocket powered aircraft.

Perhaps the most famous programme to take place during the Muroc years was the Bell X-1 (formerly XS-1). A joint venture between the Army Air Force and the National Advisory Committee for Aeronautics (NACA) the project aimed to examine flight in the transonic/supersonic regime. Having previously undertaken initial testing at Pinecastle in Florida, the X-1 needed a new home and the Mojave was the place to go. The very isolation of the location offered the still classified project a chance to develop beyond prying eyes. The clear skies and expansive landing strips were perfect for the rocket plane and so began the long association between the dry lakes and the experimental research craft – the X Planes.

On October 14th 1947, Captain Chuck Yeager flew the X-1 through Mach 1, the first recorded flight through the mythical ‘sound barrier’. As Muroc became Edwards AFB in 1949 (named for Captain Glen Edward who died, ironically, flying another of Northrop’s flying wings, the YB-49), it had already become hallowed ground for pilots wishing to go higher and faster than the rest.

Mach 2 was achieved in 1951 by NACA pilot Scott Crossfield flying the Douglas D-558-II Skyrocket, a Navy sponsored project. Air Force pride was soon regained as Chuck Yeager took the Bell X-1A past Mach 2.4. By the mid 1950’s the Bell X-2 was the new record breaker, exceeding both 100,000ft and Mach 3 for the first time, although Air Force pilot Mel Apt was killed achieving the latter record.

But when it comes to pushing back the envelope of flight milestones, one rocket powered X Plane stands above them all – the North American X-15. Born out of a co-operative project between the Air Force, Navy and NACA, the X-15 would go higher and faster than would have seemed possible only a decade before.

In 1961 Major Bob White exceeded Mach numbers 4, 5 and 6 in a series of build up flights to the research plane’s design goals. He also became the first man to truly ‘fly’ into space on 17th July 1962, reaching an altitude of 314,750 feet. Even this remarkable feat was exceeded with NASA’s Joe Walker reaching the X-15’s maximum altitude of 354,200 feet in 1963. Later in the programme the modified X-15A-2 piloted by Pete Knight reached the maximum speed of Mach 6.72, a record that still stands.

By the mid 1960’s, attention was turning to the next step – a true aerospace plane that could reach orbit, then return to land like a regular aircraft. A series of ‘lifting body’ craft, where the body of the craft itself generates the required lift, were constructed and tested by NASA and the Air Force to probe low speed approach and landing characteristics. Although these revolutionary wingless shapes were often marginal in their flight characteristics and extremely challenging to fly, they proved it was possible to return a craft capable of lifting re-entry to a controlled, precision landing without the need for additional engines.

The lifting bodies had a significant influence over the design of NASAs shuttle orbiter which also underwent approach and landing tests at Edwards in the 1970s, although its final design was far from a lifting body, with large double-delta wings to allow for extended cross-range in re-entry.

Other lifting body craft were planned, notably the X-24C, a testbed for hypersonic propulsion technologies such as Scramjets. Sadly, the money simply wasn’t there for this programme to progress beyond the planning stage (although some claim form highly circumstantial evidence that it was developed in ‘the black’ at another famous, but secret, dry lake bed).

I guess the real closing of the rocket plane circle at Edwards occurred some years later when, in April 1981, Astronauts Jon Young and Bob Crippen brought the maiden flight of the Shuttle Columbia to an end on the dry lake bed.

Edwards AFB and the associated NASA Armstrong Flight Research Centre remain busy to this day, researching the new frontiers of aeronautical knowledge, but I think it’s fair to say that Dana’s flight on September 23rd 1975 was the end of a golden era of flight.