Lockheed's Flying Gyroscope

Helicopters have won high marks in Viet Nam doing the chores they were designed for: carting supplies, ferrying troops, evacuating wounded. But, decked out with bolt-on guns and rocket launchers, the shaking, rattling and rolling choppers are less than perfect for close-in fire support. Looking for a solution, the Army last year awarded an $86 million AAFSS (Advance Aerial Fire Support System) development contract to a company that, until recently, had never been in the helicopter business at all: Lockheed Aircraft Corp.

Last week at its Van Nuys, Calif., plant, Lockheed rolled out a bug-eyed brute of a prototype that is not only faster and more sophisticated than any helicopter now flying in Viet Nam but is also a long technological hop ahead of anything in the industry. Designated the AH-56A Cheyenne, Lockheed's AAFSS is a "compound" aircraft. Like a conventional helicopter, the single-turbine Cheyenne has a main rotor and tail-mounted stabilizing rotor for hovering and vertical takeoffs and landings. In the air, a simple twist of the control-stick grip sets the pitch of the rear-mounted pusher propeller for 240-m.p.h. cross-country dashes on the craft's stubby wings.

Target-Range Marksmanship. Designed to protect conventional 140-m.p.h. Hueys and other troop-carrying choppers against ground fire, the Cheyenne will pack rockets, anti-tank missiles, a grenade launcher and belly-mounted automatic cannon. Even its looks can kill: if the gunner, using a computer and enemy-seeking infra-red sight, has his hands full with one target, the pilot, who wears a special sight-equipped helmet, can automatically take aim at another merely by glancing at it.

Lockheed's rigid-rotor design, in effect, makes the whole shebang a stable flying gyroscope. The concept--rigid blades attached directly to the rotor shaft--was tried and dropped in the '20s; experimenters found that when they tilted the rotor to change direction, the whirling blades would tumble their machines like a gyroscope gone berserk. Ever since, helicopter makers have sacrificed simplicity and speed by using flexible rotor blades mounted on heavy, complex hinges. Lockheed picked up the all-but-forgotten rigid-rotor idea in 1957--and found a way to handle it: the pilot's stick tilts only a small control rotor mounted above the main one. That, in turn, gyroscopically swings the aircraft to any desired attitude almost instantly.

Impressed by Lockheed's breakthrough, the Army may order 500 or more of the $1,000,000 Cheyennes if prototype testing is successful, have them in the field by 1970. Meanwhile, Lockheed is working up other compound-plane ideas. Among them: a 400-m.p.h. military transport with folding rotors and an intercity "air commuter" to whisk 70 passengers from one downtown district to another at 300 m.p.h.

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