by John Walker
The 1950s and 1960s were a time of great innovation in aircraft design. Speed records were set and shattered on a regular basis, and all kinds of innovative, or some may say, crazy designs were explored. One of the most curious of these was the Avro Canada VZ-9 Avrocar, which was literally a flying saucer. Developed by Avro Aircraft, Ltd. of Canada, it was initially supported by the US Air Force as an advanced fighter aircraft, and after it became clear it would never meet its performance goals, was funded by the US Army, which saw it as a kind of flying Jeep, replacing helicopters for operations in rough terrain.
The design was very odd. Lift for vertical takeoff and landing was
provided by a central “turbo-rotor” with fan blades which
created downward thrust. The rotor was powered by three jet engines
mounted in the fuselage, but they were not mechanically coupled to the
rotor like the engines in a helicopter. Instead, their jet blast was
directed at turbine blades attached to the rotor, which caused it to
spin. A portion of the rotor's thrust was diverted to thrusters
mounted around the periphery of the vehicle which the pilot could use
to orient in pitch, roll, and yaw. Later special ports were added to
the aft end of the craft to produce thrust intended to allow it to
transition from hovering to forward flight.
Looking extraordinarily cool is not a reliable guide to excellence in aircraft design, and the Avrocar demonstrated this over its brief history. Flying saucers aren't inherently stable (they might have asked the little fellows who pranged that one at Roswell!), and pilots reported that flying it was like “balancing on a beach ball.” The wobbles are apparent in the test flight film in the videos below. Diverting thrust to the attitude jets caused a loss of hovering thrust, and the saucer would bob up and down as the pilot directed its flight. In addition, the rotor acted as a powerful gyroscope which opposed changes in direction, so pilots had to compensate for its counterintuitive effects.
The Avrocar was statically unstable, and a variety of mechanical and pneumatic stability augmentation and powered control systems were added during the program. It never became easy to fly. The vehicle was tested in tethered and free flight in Canada, and in the large wind tunnel at NASA Ames in California. Numerous changes were made to the design, piling complexity on complexity, but it never managed to fly out of ground effect nor demonstrate performance comparable to the most rudimentary helicopters. It never flew above an altitude of one metre nor faster than 56 km/hour (slightly faster than a galloping horse). Even if it had the power to fly higher, it would probably not have been controllable without a computer control system which did not exist at the time. The program was cancelled in 1961.
While flying Jeeps may have been impressive in Pentagon briefings,
Congressional hearings, and articles in popular science magazines, the
reality was disappointing. Fuel economy and range would have been
terrible, requiring a costly logistics tail to cope with its thirst,
pilots would have needed extensive training to deal with its skittish
behavior (as opposed to a Jeep, which any red-blooded GI could jump in
and drive), and payloads would have been limited and required to be
carefully balanced to avoid loss of control. In all, pack mules would
probably have been more useful to the troops.
Here are three filmed progress reports on the Avrocar, declassified and restored.
Report 1: January 1958 to May 1959.
Report 2: May 1959 to April 1960.
Report 3: June 1960 to June 1961.
The Avrocar wasn't the only odd vertical takeoff aircraft of the era. The Hiller Flying Platform carried one person, who steered it by leaning in the desired direction of flight. It never exceeded a speed of 26 km/hour or an altitude of 10 metres.
This document is in the public domain.