December 1958 Popular Electronics
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My flight simulator software (MS Flight Sim 2002) and computer
I run it on (HP i7 notebook) are each more powerful than the
software and computer that ran the Douglas DC-8 pilot training
simulator featured in this 1958 article in Popular Electronics.
Two racks of 1000+
vacuum tubes did the electronic heavy lifting while massive
DC motors did the physical cockpit heavy lifting. The computer
needed to handle as many as 40 variables at one time, including
6 differential equations of motion. 100 servomotors, 540 amplifiers
and 2,200 gears drove the instrument panel gauges, dials, and
movie projector mechanisms. The instrument panel description
conjures images of the inside of a modern office-grade copying
machine with its very dense conglomeration of gears and axels
(have you seen the inside of one of those lately?).
Flying High at Zero Altitude
By Ben Preece
The pilot and co-pilot of the Douglas DC-8 Jetliner couldn't
see anything through the windshield. It was totally dark outside.
The altimeter was winding down as the giant plane dropped through
the overcast. The crew chief watched his instrument panel.
"We'll be out in a minute," the pilot said, referring to
the cloud bank he'd been in since take-off. Then the lights
of the field appeared below.
"There it is," the copilot gestured. A bright, double row
of lights, outlining the runway, could be seen ahead and below.
The DC-8 Jetliner dropped slowly until it was over the runway.
The pilot pulled the nose up, there was a slight bump, then
a squeal of tires as the brakes were applied, and the ship had
The pilot, copilot and crew chief had just experienced a
coast-to-coast flight. However, their greatest altitude had
been under ten feet, the greatest speed zero miles an hour.
Yet, except for the gravitational forces, this crew had experienced
every sensation of being in an airplane flying five hundred
miles per hour at 35,000 feet. They had just completed a "ride"
in the DC-8 flight simulator!
The DC-8 simulator works electronically to produce all the
sensations of flying, including correct instrument readings,
climb and bank altitudes, everything. It even has a closed-circuit
television system which shows you an airfield, just as you would
see it in the real DC-8.
An artist's concept of the DC-8 Jetliner
simulator setup. As the pilot "flies" the simulator, a television
camera traces the plane's path along a three-dimensional model
of an airport and approach area on the rear wall. The TV picture
is projected on the screen in front of the cockpit. At the side
of the room are racks which house the electronic "brain" of
Such simulators train pilots to fly planes that haven't rolled
off the assembly line.
Swift, new planes like the Douglas DC-8, the Boeing 707 and
the Lockheed Electra will be "old hat" to airline pilots when
they go into service.
A DC-8 simulator is as realistic as the actual airplane.
It consists of a cockpit section, a scale model airport, a closed-circuit
television system, and a computer system and servomechanisms
to control the position of the cockpit section.
Pilots learn to fly the Douglas DC-8 Jetliner
on terra firma. Here, a pilot "checks out" for the first time.
The cockpit exactly duplicates the DC-8 controls. Closed-circuit
TV projector provides realistic visual impression encountered
during landings and take-offs. The simulator was produced by
Link Aviation, Inc.
Realism in Training.
The cockpit has all the dials, levers and gauges of the DC-8
itself. When the pilot "flies" the simulator, he experiences
all the motions he would feel in real flight, except the g-loads.
There are air pockets, sudden wind gusts, the sound of the jet
engines, even the two quick jars the real DC-8 feels when it
slips into a bank at high altitude and the wings lose their
The crew of the simulator consists of the pilot, copilot,
crew chief and instructor. Additional personnel outside operate
the radio signal system and the closed-circuit television. The
instructor can simulate any emergency a pilot will find in flight.
The crew in the radio control room can duplicate the signal
of any radio station in the world, and send six signals at once.
Thus, the pilot may receive every radio indication that he is
flying over Chicago, New York, Los Angeles or London. The radio
crew can even vary the compass reading to allow for the magnetic
variation typical in any part of the world.
The simulated DC-8 Jetliner's flight is traced
on these maps in the control room of the simulator. The instructor
makes the necessary control tower and check-point voice communications.
Controls at the extreme right provide radio and navigation signals.
In short, once the pilot and his crew take their seats, they
are in a real airplane. When the jet engines are running, the
cockpit may buck against the brakes, depending upon the throttle
setting. When the brakes are released...off they go! The runway
lights whirl by on either side. Looking straight ahead, the
crew has the illusion of motion as the lights go by.
In the air, the instructor throws the book at the pilot.
Engine failure may "occur," hydraulic failure, cooling system
failure, a change in the plane's center of gravity, or any other
trouble. More than one pilot has been saved by his simulator
training. It teaches him to think fast and to do the right thing
in a split second.
The DC-8 simulator does everything but fly. "It's really
an electronic brain," one engineer said. "It must handle as
many as forty variables at one time, including the six differential
equations of motion. Then it must solve the problem and translate
the answer into airplane motion, instrument readings and a visual
television picture for the pilot."
Among those forty variables are engine thrust, fuel pressure,
Mach number, altitude, rate of climb or descent, and many others.
D.C. circuits are used throughout for several reasons. Direct
current provides a higher degree of accuracy, eliminates the
possibility of phase shift, harmonic distortion, erratic instrument
motion and noise pickup. The circuits are simpler and therefore
easier to maintain. Direct current also eliminates the fluctuations
and variations inherent in most of the alternating current supplies.
The DC-8 simulator uses printed-circuit boards and utilizes
various electronic systems. For example: the characteristics
of the engines are carried electronically on one circuit board.
If another engine with an extra 500 horsepower is to be inserted,
the old engine circuit board is removed and the new one plugged
in. This way "engines" can be switched in only half an hour.
A room behind the cockpit section is lined with tall, grey
cabinets. On the left are racks holding various amplifiers and
other electronic gear. On the right are small circuit boards
and motors with spinning dials. Under each unit is a label:
Fuel Flow, Bank, Altitude, etc. The computer essentially takes
a rate of change, integrates it, and tells the crew through
cockpit motion or instrument readings just what is happening.
In the TV room there is a model airport made to scale mounted
on a long wall. A television camera is mounted on two tracks
which run the length of the model airport. The model is built
to a three-hundred- to-one scale, and represents an area 21,000
feet by 3000 feet. The TV camera is connected to the computer
system. If the pilot dives, the camera tilts down. If he climbs,
the camera tilts up. It follows every motion of the airplane,
so it sees what the pilot would see. The picture is then flashed
on the screen in front of the pilot.
A television camera scans a miniature relief
map built to a 300:1 scale. The camera is automatically positioned
along the aircraft course and altitude, and assumes the aircraft
attitude. Movement of camera is governed by electronic response
of simulated Jetliner to pilot's controls. The relief map is
wall-mounted to save floor space.
A television projector is located on top of the DC-8 simulator
cockpit. And the televised picture from the map room is projected
onto a motion picture screen which covers the visible area viewed
by the pilots in training.
The DC-8 simulator gives to the public a well-trained, proficient
crew. This flying team practices and "polishes" on the ground.
When the Jetliners are put into operation, the passengers can
be sure that the pilot and his crew have many hours of simulated
and actual flying time under their belts. The simulator offers
safety through practice.
"Brain" of the simulator. Two rows of electronic
devices comprise the analog computers and servomechanisms. In
addition to literally thousands of electron tubes and resistors,
the "brain" contains 100 servo motor-generator sets, 540 amplifiers
and 2200 gears.
Posted April 1, 2013