Radar

The invention: An electronic system for detecting objects at great

distances, radar was a major factor in the Allied victory ofWorld

War II and now pervades modern life, including scientific research.

The people behind the invention:

Sir Robert Watson-Watt (1892-1973), the father of radar who

proposed the chain air-warning system

Arnold F. Wilkins, the person who first calculated the intensity

of a radio wave

William C. Curtis (1914-1976), an American engineer

Looking for Thunder

Sir RobertWatson-Watt, a scientist with twenty years of experience

in government, led the development of the first radar, an acronym

for radio detection and ranging. “Radar” refers to any instrument

that uses the reflection of radio waves to determine the

distance, direction, and speed of an object.

In 1915, during World War I (1914-1918), Watson-Watt joined

Great Britain’s Meteorological Office. He began work on the detection

and location of thunderstorms at the Royal Aircraft Establishment

in Farnborough and remained there throughout the

war. Thunderstorms were known to be a prolific source of “atmospherics”

(audible disturbances produced in radio receiving apparatus

by atmospheric electrical phenomena), andWatson-Watt

began the design of an elementary radio direction finder that

gave the general position of such storms.





Research continued after

the war and reached a high point in 1922 when sealed-off

cathode-ray tubes first became available. With assistance from

J. F. Herd, a fellow Scot who had joined him at Farnborough, he

constructed an instantaneous direction finder, using the new

cathode-ray tubes, that gave the direction of thunderstorm activity.

It was admittedly of low sensitivity, but it worked, and it was

the first of its kind.Watson-Watt did much of this work at a new site at Ditton Park,

near Slough, where the National Physical Laboratory had a field

station devoted to radio research. In 1927, the two endeavors were

combined as the Radio Research Station; it came under the general

supervision of the National Physical Laboratory, withWatson-Watt

as the first superintendent. This became a center with unrivaled expertise

in direction finding using the cathode-ray tube and in studying

the ionosphere using radio waves. No doubt these facilities

were a factor when Watson-Watt invented radar in 1935.

As radar developed, its practical uses expanded. Meteorological

services around the world, using ground-based radar, gave warning

of approaching rainstorms. Airborne radars proved to be a great

help to aircraft by allowing them to recognize potentially hazardous

storm areas. This type of radar was used also to assist research into

cloud and rain physics. In this type of research, radar-equipped research

aircraft observe the radar echoes inside a cloud as rain develops,

and then fly through the cloud, using on-board instruments to

measure the water content.

Aiming Radar at the Moon

The principles of radar were further developed through the discipline

of radio astronomy. This field began with certain observations

made by the American electrical engineer Karl Jansky in 1933

at the Bell Laboratories at Holmdell, New Jersey. Radio astronomers

learn about objects in space by intercepting the radio waves that

these objects emit.

Jansky found that radio signals were coming to Earth from space.

He called these mysterious pulses “cosmic noise.” In particular, there

was an unusual amount of radar noise when the radio antennas were

pointed at the Sun, which increased at the time of sun-spot activity.

All this information lay dormant until after World War II (1939-

1945), at which time many investigators turned their attention to interpreting

the cosmic noise. The pioneers were Sir Bernard Lovell at

Manchester, England, Sir Martin Ryle at Cambridge, England, and

Joseph Pawsey of the Commonwealth of Science Industrial Research

Organization, in Australia. The intensity of these radio waves was

first calculated by Arnold F.Wilkins.

As more powerful tools became available toward the end of

World War II, curiosity caused experimenters to try to detect radio

signals from the Moon. This was accomplished successfully in the

late 1940’s and led to experiments on other objects in the solar system:

planets, satellites, comets, and asteroids.

Impact

Radar introduced some new and revolutionary concepts into warfare,

and in doing so gave birth to entirely new branches of technology.

In the application of radar to marine navigation, the long-range

navigation system developed during the war was taken up at once

by the merchant fleets that used military-style radar equipment

without modification. In addition, radar systems that could detect

buoys and other ships and obstructions in closed waters, particularly

under conditions of low visibility, proved particularly useful

to peacetime marine navigation.

In the same way, radar was adopted to assist in the navigation of

civil aircraft. The various types of track guidance systems developed after the war were aimed at guiding aircraft in the critical last

hundred kilometers or so of their run into an airport. Subsequent

improvements in the system meant that an aircraft could place itself

on an approach or landing path with great accuracy.

The ability of radar to measure distance to an extraordinary degree

of accuracy resulted in the development of an instrument that

provided pilots with a direct measurement of the distances between

airports. Along with these aids, ground-based radars were developed

for the control of aircraft along the air routes or in the airport

control area.

The development of electronic computers can be traced back to

the enormous advances in circuit design, which were an integral part

of radar research during the war. During that time, some elements

of electronic computing had been built into bombsights and other

weaponry; later, it was realized that a whole range of computing operations

could be performed electronically. By the end of the war,

many pulse-forming networks, pulse-counting circuits, and memory

circuits existed in the form needed for an electronic computer.

Finally, the developing radio technology has continued to help

astronomers explore the universe. Large radio telescopes exist in almost

every country and enable scientists to study the solar system

in great detail. Radar-assisted cosmic background radiation studies

have been a building block for the big bang theory of the origin of

the universe.

Pyrex glass

The invention: Asuperhard and durable glass product with widespread

uses in industry and home products.

The people behind the invention:

Jesse T. Littleton (1888-1966), the chief physicist of Corning

Glass Works’ research department

Eugene G. Sullivan (1872-1962), the founder of Corning’s

research laboratories

William C. Taylor (1886-1958), an assistant to Sullivan

Cooperating with Science

By the twentieth century, Corning GlassWorks had a reputation

as a corporation that cooperated with the world of science to improve

existing products and develop new ones. In the 1870’s, the

company had hired university scientists to advise on improving the

optical quality of glasses, an early example of today’s common practice

of academics consulting for industry.

When Eugene G. Sullivan established Corning’s research laboratory

in 1908 (the first of its kind devoted to glass research), the task

that he undertook withWilliam C. Taylor was that of making a heatresistant

glass for railroad lantern lenses. The problem was that ordinary

flint glass (the kind in bottles and windows, made by melting

together silica sand, soda, and lime) has a fairly high thermal expansion,

but a poor heat conductivity. The glass thus expands

unevenly when exposed to heat. This condition can cause the glass

to break, sometimes violently. Colored lenses for oil or gas railroad

signal lanterns sometimes shattered if they were heated too much

by the flame that produced the light and were then sprayed by rain

or wet snow. This changed a red “stop” light to a clear “proceed”

signal and caused many accidents or near misses in railroading in

the late nineteenth century.



Two solutions were possible: to improve the thermal conductivity

or reduce the thermal expansion. The first is what metals do:

When exposed to heat, most metals have an expansion much greater  

than that of glass, but they conduct heat so quickly that they expand

nearly equally throughout and seldom lose structural integrity from

uneven expansion. Glass, however, is an inherently poor heat conductor,

so this approach was not possible.

Therefore, a formulation had to be found that had little or no

thermal expansivity. Pure silica (one example is quartz) fits this description,

but it is expensive and, with its high melting point, very

difficult to work.

The formulation that Sullivan and Taylor devised was a borosilicate

glass—essentially a soda-lime glass with the lime replaced by

borax, with a small amount of alumina added. This gave the low thermal

expansion needed for signal lenses. It also turned out to have

good acid-resistance, which led to its being used for the battery jars

required for railway telegraph systems and other applications. The

glass was marketed as “Nonex” (for “nonexpansion glass”).

From the Railroad to the Kitchen

Jesse T. Littleton joined Corning’s research laboratory in 1913.

The company had a very successful lens and battery jar material,

but no one had even considered it for cooking or other heat-transfer

applications, because the prevailing opinion was that glass absorbed

and conducted heat poorly. This meant that, in glass pans,

cakes, pies, and the like would cook on the top, where they were exposed

to hot air, but would remain cold and wet (or at least undercooked)

next to the glass surface. As a physicist, Littleton knew that

glass absorbed radiant energy very well. He thought that the heatconduction

problem could be solved by using the glass vessel itself

to absorb and distribute heat. Glass also had a significant advantage

over metal in baking. Metal bakeware mostly reflects radiant energy

to the walls of the oven, where it is lost ultimately to the surroundings.

Glass would absorb this radiation energy and conduct it evenly to

the cake or pie, giving a better result than that of the metal bakeware.

Moreover, glass would not absorb and carry over flavors from

one baking effort to the next, as some metals do.

Littleton took a cut-off battery jar home and asked his wife to

bake a cake in it. He took it to the laboratory the next day, handing

pieces around and not disclosing the method of baking until all had

agreed that the results were excellent. With this agreement, he was

able to commit laboratory time to developing variations on the

Nonex formula that were more suitable for cooking. The result was

Pyrex, patented and trademarked in May of 1915.

Impact

In the 1930’s, Pyrex “Flameware” was introduced, with a new

glass formulation that could resist the increased heat of stovetop

cooking. In the half century since Flameware was introduced,

Corning went on to produce a variety of other products and materials:

tableware in tempered opal glass; cookware in Pyroceram, a

glass product that during heat treatment gained such mechanical

strength as to be virtually unbreakable; even hot plates and stoves

topped with Pyroceram.

In the same year that Pyrex was marketed for cooking, it was

also introduced for laboratory apparatus. Laboratory glassware

had been coming from Germany at the beginning of the twentieth

century; World War I cut off the supply. Corning filled the gap

with Pyrex beakers, flasks, and other items. The delicate blownglass

equipment that came from Germany was completely displaced

by the more rugged and heat-resistant machine-made Pyrex

ware.

Any number of operations are possible with Pyrex that cannot

be performed safely in flint glass: Test tubes can be thrust directly

into burner flames, with no preliminary warming; beakers and

flasks can be heated on hot plates; and materials that dissolve

when exposed to heat can be made into solutions directly in Pyrex

storage bottles, a process that cannot be performed in regular

glass. The list of such applications is almost endless.

Pyrex has also proved to be the material of choice for lenses in

the great reflector telescopes, beginning in 1934 with that at Mount

Palomar. By its nature, astronomical observation must be done

with the scope open to the weather. This means that the mirror

must not change shape with temperature variations, which rules

out metal mirrors. Silvered (or aluminized) Pyrex serves very well,

and Corning has developed great expertise in casting and machining

Pyrex blanks for mirrors of all sizes.

Propeller-coordinated machine gun

The invention: A mechanism that synchronized machine gun fire

with propeller movement to prevent World War I fighter plane

pilots from shooting off their own propellers during combat.

The people behind the invention:

Anthony Herman Gerard Fokker (1890-1939), a Dutch-born

American entrepreneur, pilot, aircraft designer, and

manufacturer

Roland Garros (1888-1918), a French aviator

Max Immelmann (1890-1916), a German aviator

Raymond Saulnier (1881-1964), a French aircraft designer and

manufacturer

French Innovation

The first true aerial combat ofWorldWar I took place in 1915. Before

then, weapons attached to airplanes were inadequate for any

real combat work. Hand-held weapons and clumsily mounted machine

guns were used by pilots and crew members in attempts to

convert their observation planes into fighters. On April 1, 1915, this

situation changed. From an airfield near Dunkerque, France, a

French airman, Lieutenant Roland Garros, took off in an airplane

equipped with a device that would make his plane the most feared

weapon in the air at that time.

During a visit to Paris, Garros met with Raymond Saulnier, a French

aircraft designer. In April of 1914, Saulnier had applied for a patent on

a device that mechanically linked the trigger of a machine

gun to a cam

on the engine shaft. Theoretically, such an assembly would allow the

gun to fire between the moving blades of the propeller. Unfortunately,

the available machine gun Saulnier used to test his device was a

Hotchkiss gun, which tended to fire at an uneven rate. On Garros’s arrival,

Saulnier showed him a new invention: a steel deflector shield

that, when fastened to the propeller, would deflect the small percentage

of mistimed bullets that would otherwise destroy the blade.

The first test-firing was a disaster, shooting the propeller off and

destroying the fuselage. Modifications were made to the deflector

braces, streamlining its form into a wedge shape with gutterchannels

for deflected bullets. The invention was attached to a

Morane-Saulnier monoplane, and on April 1, Garros took off alone

toward the German lines. Success was immediate. Garros shot

down a German observation plane that morning. During the next

two weeks, Garros shot down five more German aircraft.

German Luck

The German high command, frantic over the effectiveness of the

French “secret weapon,” sent out spies to try to steal the secret and

also ordered engineers to develop a similar weapon. Luck was with

them. On April 18, 1915, despite warnings by his superiors not to fly

over enemy-held territory, Garros was forced to crash-land behind

German lines with engine trouble. Before he could destroy his aircraft,

Garros and his plane were captured by German troops. The secret

weapon was revealed.

The Germans were ecstatic about the opportunity to examine

the new French weapon. Unlike the French, the Germans had the

first air-cooled machine gun, the Parabellum, which shot continuous

bands of one hundred bullets and was reliable enough to be

adapted to a timing mechanism.

In May of 1915, Anthony Herman Gerard Fokker was shown

Garros’s captured plane and was ordered to copy the idea. Instead,

Fokker and his assistant designed a new firing system. It is unclear

whether Fokker and his team were already working on a synchronizer

or to what extent they knew of Saulnier’s previous work in

France.Within several days, however, they had constructed a working

prototype and attached it to a Fokker Eindecker 1 airplane. The

design consisted of a simple linkage of cams and push-rods connected

to the oil-pump drive of an Oberursel engine and the trigger

of a Parabellum machine gun. The firing of the gun had to be timed

precisely to fire its six hundred rounds per minute between the

twelve-hundred-revolutions-per-minute propeller blades.

Fokker took his invention to Doberitz air base, and after a series of exhausting trials before the German high command, both on the

ground and in the air, he was allowed to take two prototypes of the

machine-gun-mounted airplanes to Douai in German-held France.

At Douai, two German pilots crowded into the cockpit with Fokker

and were given demonstrations of the plane’s capabilities. The airmen

were Oswald Boelcke, a test pilot and veteran of forty reconnaissance

missions, and Max Immelmann, a young, skillful aviator

who was assigned to the front.

When the first combat-ready versions of Fokker’s Eindecker 1

were delivered to the front lines, one was assigned to Boelcke, the

other to Immelmann. On August 1, 1915, with their aerodrome under attack from nine English bombers, Boelcke and Immelmann

manned their aircraft and attacked. Boelcke’s gun jammed, and he

was forced to cut off his attack and return to the aerodrome. Immelmann,

however, succeeded in shooting down one of the bombers

with his synchronized machine gun. It was the first victory credited

to the Fokker-designed weapon system.

Impact

At the outbreak of World War I, military strategists and commanders

on both sides saw the wartime function of airplanes as a

means to supply intelligence information behind enemy lines or as

airborne artillery spotting platforms. As the war progressed and aircraft

flew more or less freely across the trenches, providing vital information

to both armies, it became apparent to ground commanders

that while it was important to obtain intelligence on enemy

movements, it was important also to deny the enemy similar information.

Early in the war, the French used airplanes as strategic bombing

platforms. As both armies began to use their air forces for strategic

bombing of troops, railways, ports, and airfields, it became evident

that aircraft would have to be employed against enemy aircraft to

prevent reconnaissance and bombing raids.

With the invention of the synchronized forward-firing machine

gun, pilots could use their aircraft as attack weapons. Apilot finally

could coordinate control of his aircraft and his armaments with

maximum efficiency. This conversion of aircraft from nearly passive

observation platforms to attack fighters is the single greatest innovation

in the history of aerial warfare. The development of fighter

aircraft forced a change in military strategy, tactics, and logistics and

ushered in the era of modern warfare. Fighter planes are responsible

for the battle-tested military adage: Whoever controls the sky controls

the battlefield.