The Road to the Future… Is Paved With Good Inventions
We bring you 10 great ideas that made flying safer, easier, or just a whole lot more fun.
- Air & Space magazine, September 2009
NASM (SI 76-17595-P)
The Tomcat’s Brain
As a 1968 graduate in electronic engineering, Raymond Holt was in a sandwich generation, caught between vacuum tubes and transistors. When he showed up for his first job, at Garrett AiResearch, the personnel manager told him he was the only one in his department who’d had a class in computer design. AiResearch had just been hired by the Grumman Corporation to design the F-14 Tomcat’s central air data computer, a microprocessor that would, with data from pressure sensors, calculate and report (on cockpit displays) Mach number, altitude, and airspeed, and, accordingly, move the aircraft’s control surfaces and adjust the sweep of its variable geometry wing. AiResearch had designed the McDonnell F-4 Phantom’s central air data computer, but that had been electromechanical. “It had gears and cams,” says Holt. “It’s like a transmission on a car, except that it’s chrome and gold. It was about two feet long and three feet high. When they showed it to me and said I had to make it electronic [to fit on a circuit board 40 inches square] I about freaked out.”
Northrop Grumman engineer Dave Wolfe worked at Garrett AiResearch at the time, where his job was teaching Grumman technicians how the F-14’s central air data computer worked. (“I saw the airplane and I was so impressed that I left [AiResearch] and joined Grumman,” he says.)
“Electromechanical systems were a maintenance nightmare,” says Wolfe. “You needed a very special type of artisan to repair those things — almost a watchmaker. People were looking for something to replace that system.” Garrett AiResearch was the only company to submit a bid for a digital, instead of electromechanical, design, but the small, powerful processors required didn’t exist.
In 1968, the integrated circuit was 10 years old. Jack Kilby of Texas Instruments and Robert Noyce of Intel Corporation had independently developed methods for assembling transistors — switches that in the binary language of computers say “on” or “off” —on a single slice, or chip, of a semi-conducting metalloid, like silicon. (Kilby’s work won him the 2000 Nobel Prize in Physics.)
As a 10-year-old, the integrated circuit had come a long way. It could integrate hundreds of transistors on a single chip, as opposed to the first integrated circuits, used on the Apollo guidance computer, which made do with tens. But it hadn’t come far enough for the F-14’s computer, which demanded as many as 3,500 transistors on a single chip.
In 1968, the circuits were mapped on huge, multi-color Mylar sheets “the size of an entire wall of a commercial building,” recalls Holt. The degree to which that layout could be shrunk — and its detail preserved — to form the pattern for etching on a chip was one limit to a chip’s capacity.
Holt’s team and chip maker American Microsystems created a six-chip processor containing 65,000 bits of data, an achievement Holt believes has been unrecognized because of semantics. Intel Corporation gets credit for producing the first single-chip microprocessor in 1971, but Holt contends that with the F-14A’s first flight in 1970, his team beat Intel to the first microprocessor by a year. Unfortunately, a hydraulic failure on the first flight caused the F-14 to crash (the pilot safely ejected), but the central air data computer performed flawlessly.
The Whiz Wheel
Since 1940, the E6B, a circular slide rule, has been the student pilot’s computer of choice. Invented by Navy man Philip Dalton and developed with celebrated navigator Philip Van Horn Weems, the device, also called the Dalton Dead Reckoning Computer and the Whiz Wheel, was embraced by the Army Air Forces during World War II, and has changed little since. The logarithmic slide rule uses arithmetic to calculate speed, flight time, distance, fuel burn, and density altitude; the wheel on the reverse side uses trigonometry to calculate how wind will affect cruise flight.
The E6B has made a few appearances on “Star Trek.” In the episode “The Naked Time,” Mr. Spock uses a Whiz Wheel to calculate precisely when the Enterprise will smash into a planet. It’s likely this prop came from the flight bag of series creator Gene Roddenberry or designer Matt Jeffries, both of whom were pilots.
Although many students today use an electronic version, some prefer the plastic or aluminum original. In a debate over the pros and cons of plastic on the Jetcareers Web site, one poster says, “1) It never [exhausts] batteries. 2) It’s smaller and lighter. 3) I am actually quicker with it. 4) (most important) I am an enormous nerd.” However, the Major Nerd award goes to Stefan Vorkoetter, who notes on Stefan’s General Aviation Web site, “The calculator side is also handy for computing tips or comparing unit prices of items in the grocery store.”
EZ Does It
Burt Rutan hadn’t intended to start a homebuilders’ revolution in 1975; he just wanted to break a record. He’d been experimenting with canards —airfoils mounted forward of the wings — and hoped to demonstrate that an aircraft equipped with them would outperform conventional types. He was thinking about getting into the homebuilt market, and setting a record, he reasoned, would sell a lot of plans.
He wanted to build his record contender quickly, and be able to modify it easily, so he scrapped the aluminum prototype he was working on and borrowed construction techniques from a business that repaired fiberglass sailplanes at Mojave Airport, near his shop. The repair business didn’t have factory tooling. For repairs, Rutan says, “they would put in position the foam core and then they’d fiberglass both sides. And I got the inspiration from that and also from something else: I was a model airplane guy since I was 10 years old. And model airplanes then made their wings with hot-wire-cut foam cores. And I put both of those ideas together — of repairing fiberglass sailplanes and building radio-controlled model wings —and came up with this method whereby you could build an airplane without any molds.”