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Archive for the ‘STEM’ Category

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SciTech Tuesday: Radar Research Led to Astronomical Discoveries

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JS Hey died on 27 February of 2000, at the age of 81.

Born in Lancashire, England, he was the third son of a cotton manufacturer. He entered University of Manchester and got his degree in physics in 1930, and a masters in x-ray crystallography in 1931.

Hey taught physics at schools in Northern England until 1942, when he joined the Army Operational Research Group. We was assigned to work on radar jamming. At that point the Allies were using a form of radar with relatively long waves. Axis forces could not only detect this radar, but jam it. Using radar jamming two German warships had recently escaped through the English Channel. At the same time the Allies were losing an unsustainable tonnage of cargo to U-Boats in the Atlantic.

75 years ago this month Hey was monitoring radar jamming when he noticed a great deal of noise in the 4-8 m jamming Allied radar sets. Following the source, he noticed that it moved slowly, tracking the sun. Looking up meteorological data, he discovered that the Sun had a very active solar spot that day. Solar spots had been hypothesized to produce streams of ions and magnetic fields. Hey interpreted the phenomenon of the radar jamming as support of this hypothesis.

Development of radar using much shorter waves generated by the cavity magnetron allowed the Allies to avoid jamming by the Axis powers. Using this microwave radar Hey was tracking V2 rockets heading towards London in 1945 when he noticed transient radar echoes at about 60 miles of altitude. The echoes arrived at a rate of 5-10 per hour and persisted after the V2s were gone. It turned out the echoes were the vapor trails of meteors, and Hey showed that meteors could be tracked this way in the day when they were not visible to the eye.

JS Hey was not able to publish his results until after the war, for security reasons. Shortly after the war he was appointed to head the Army Operational Research Group, and he worked at the Royal Radar Establishment, where he continued his work in radio astronomy.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum

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SciTech Tuesday: The 75th Anniversary of the Battle of Los Angeles

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The night of February 24, 1942, and the hours before dawn of the 25th, the sky over Los Angeles was lit by search lights, the city was under a blackout, and more than 1.400 shells were shot from .50 caliber guns into the air. When the all-clear was sounded at 7:21 AM on the 25th, the only casualties were buildings and cars hit by shell fragments, and 3 civilians killed in car accidents.

The immediate cause of the false alarm was a rogue weather balloon. When spotted from the ground by nervous watchers, lit from underneath by search lights, it was identified as an enemy aircraft.

The real cause was nervousness and a heightened watchfulness that resulted from events on the previous day, a short ways up the California coast.

On the evening of February 23, President Roosevelt delivered a fireside chat radio broadcast. Less than three months since the attack on Pearl Harbor, the nation was anxious, and in the midst of preparations for war. In the speech, Roosevelt said “…the broad oceans which have been heralded in the past as our protection from attack have become endless battlefields on which we are constantly being challenged by our enemies.’’ In the weeks since Pearl Harbor the United States had heard more bad news of advancing Japanese forces across the Pacific Ocean and Asia, and U-boat attacks from the German Navy in the Atlantic.

Perhaps as a means to undermine Roosevelt’s confident speech, a Japanese submarine patrolling the West Coast surfaced offshore north of Santa Barbara, and launched 13 shells towards oil wells and equipment in Ellwood, CA. It completely missed the gasoline plant there, caused minor damage to the piers and wells, and stayed 2,500 yards offshore, but the submarine’s impact on popular anxiety was great. The night of the shelling the Army Air Force sent a handful of pursuit planes and bombers to find the submarine, but was loath to commit more forces.

Intelligence supplied by loyal Japanese Americans had suggested that there might be some action to disturb the President’s speech. It also suggested that Los Angeles might be attacked the next night. The state of readiness itself led to the false alarm.

Confused reports from the night of the event, secrecy after it, and anxiety led to many conspiracy theories. This might even be counted as one of the first major events in the history of UFO conspiracies. Radar sightings of the objects triggering the artillery fire suggested they were moving far too slowly to have been planes. The use of radar for these purposes was new, and inexperienced operators may have been part of the problem. Visual sighting under night conditions is unreliable. Without context objects like weather balloons in the sky, especially with uncertain lighting, are difficult to scale.

The event led to better coordination of civilian and military defenses on the West Coast, and to more surveillance of activities and objects around plants and other installations near the shore. It might also have contributed to popular sentiment in support of Japanese Internment. Roosevelt had authorized Executive Order 9066 just days before.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum

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SciTech Tuesday: Radio and the Electromagnetic Spectrum

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Today, TV screens are everywhere. There are several in most American homes, most restaurants and bars have them, they dominate the electronics sections of stores.

During WWII, radio filled that niche in electronics and mass communication. During national elections and other big events or disasters today, we gather around televisions to find out what is happening. During World War II, families gathered around radios. They had their days to hear their favorite programs, as I remember Sunday nights watching nature programs on TV with my family.

The technology underlying the radio and the television are basically the same. Manipulation of an electromagnetic field creates waves in a part of the electromagnetic spectrum at the transmitter. At some distance these waves are turned into an electrical current again by a receiver. In radios the receiver’s current makes a magnet attached to a paper or fabric cone move and generate sound waves. In the original televisions, the current was used in a cathode-ray tube (CRT) to make patterns on a phosphorescent screen. Today’s televisions put a current through a matrix of materials that responds to current by making different colors.

The original radio waves transmitted by Marconi in the 1890s could only travel a couple of miles. Since then, engineers have developed ways to make all sorts of different electromagnetic waves. These made radio better, but also made RADAR possible, and microwaves, and x-ray machines (the first x-rays were made with radioactive material but now they use electronically generated energy).

We are constantly in fields of anthropogenic electromagnetic waves. They come unintentionally from the electricity in the buildings we live in. The come intentionally from all sorts of devices. The many remote controls in a home, the cell phones, wireless phones, Wi-Fi routers, Bluetooth devices—all of these use electromagnetic waves to communicate at a distance. (As an aside, land-line phones and cable signals come into your home as electrical currents, but satellite services uses waves).

Much of the consumer technology of the last century has been about finding better and better ways to harness electromagnetic waves. Amplitude modulation (AM) of waves was replaced by Frequency Modulation (FM)—although AM is still used and has its uses. Broadcasters have recently been adding HD signals, which can contain more information in waves. That’s why multiple broadcast “stations” can be received at a single frequency of waves.

World War II was a huge time for the expansion of this engineering. Necessity then for portable radios drove miniaturization and vacuum-tube technology. RADAR development created shorter wavelength generation. Cleaning up radio reception led to the discovery of cosmic background radiation and also led to radio astronomy.

Compared to 75 years ago, the technology we use today to communicate and entertain may seem completely different. But in essence it is still the manipulation of electricity to make electromagnetic waves to be received at a distance.

You can find archived radio news broadcasts from WWII here.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

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SciTech Tuesday: Sikorsky and the helicopter.

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On 14 January 1942 Sikorsky Aircraft successfully flew for the first time the contraption later called the YR-4 (or the Hoverfly in England). This rotary winged craft became the first mass-produced helicopter.

In a test flight it went from the company’s Connecticut headquarters to Wright Air Field in Ohio (over 700 miles) with a ceiling of 12,000 feet and a top speed of 90 mph. Within a year the US Army Air Force and the Royal Navy were testing prototypes. After the engine capacity was increased (to 165 hp) and stability improved by increasing the rotor length and displacement of the tail rotor, the helicopter went to training and field testing.

The first mission in which the YR-4 was used was a combat rescue mission in the China=Burma theater in April of 1943. Throughout the war it was used primarily for rescue missions.

Igor Sikorsky, who designed this craft, was a Russian immigrant born in Ukraine in 1889. His story is one that reflects many from the time, and resonates today. He studied engineering in Paris and Kiev, and established a successful company building aircraft, including bombers for Russian forces in WWI. He briefly worked for the French forces in Russia as an engineer, but believing the October Revolution to threaten both his career and life, he emigrated to the US in 1919. He worked as a school teacher in NY  until he obtained a position on the engineering faculty at the University of Rhode Island in 1933. In 1923, with backing from Russian expats like Rachmaninov, he formed the Sikorsky Manufacturing Company and built the one of the first dual-engined planes in the US. This plane, the S-29, carried 14 passengers and could fly at 115mph. His company was acquired by United Aircraft and Transport Company (today’s United Technologies Corporation) in 1929, and he helped them make the boat-planes that Pan-Am used for its cross-Atlantic routes.

He married in 1924 and became a naturalized citizen in 1928. He lived until 1972. Always a devout Russian Orthodox Christian, he authored 3 books, one about his helicopters, and two about theology.

 

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

all images from Wikimedia Commons

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SciTech Tuesday: The Development of an American Icon of WWII

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Now a quintessentially American icon, the P-51 Mustang had very English origins. That famous plane, used by the Eighth Air Force over western Europe to defend bombers, the ride of the Tuskegee Airmen, was displaced from the front of the US air arsenal only when jets arrived. But before it was replaced it also served in the North African, Mediterranean, Italian and Pacific Theater in WWII, and well into the Korean War.

However, the first of these planes were built by North American Aviation (NAA) in 1940 to fill an order for the British Purchasing Commission. The commission had asked for P-40s for the Royal Air Force, but rather than licensing from Curtiss, NAA proposed an upgraded design. The purchase and delivery of the planes came under the famous Lend-Lease agreement, and they were named Mustang Mk1.

The plane was meant to be a tactical-reconnaissance fighter and bomber to be used a relatively low altitudes. The range on the planes was much longer than the planes the British were using. The Allison engine in the original planes had a single-stage supercharger. This limited the power of the engine at high altitudes. After a test flight, Ronald Harker of Rolls Royce was impressed with everything about the plane but its power-plant. He suggested that the Merlin 61, which was being used in the latest Spitfires, would do very well in the aircraft, and even made some rough measurements of the engine compartment to verify that it would fit. The Merlin 61 was designed with a two-stage intercooled supercharger that increased horsepower and operational altitude and speed. The heavier engine gave engineers a chance to add an additional fuel tank behind the pilot, that balanced the center of gravity and provided longer range.

The Merlin 61 was licensed to Packard to build in the US as the V-1650 Merlin. Packard was building and shipping them to England to supplement production there. Addition of the two-stage supercharger had been made for use in the British Wellington VI bomber, and was later used for Spitfires as well.

After encouragement, NAA switched the power-plant in the Mustang MK1 to the Merlin, and the plane was made for the USAAF as well—as the P-51 Mustang.

Although much of the power-plant engineering was British, the critical two-stage supercharger was French, and the Americans added a new alloy to the ball bearings that prevented wear and decreased maintenance. The amazing aerodynamics of the plane—the airfoil of its wings has very low drag at high speed—were all American.

Much of what you see on the outside of the iconic American plane is American—but inside you’ll find some British and a little French. Like much of the rest of the story of WWII, cooperation among allies was the key to victory.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

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SciTech Tuesday: Percy Julian and ‘Bean Soup’

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During WWII the Navy used a foam to put out fires of oil and gasoline. This foam was called Aer-O-Foam, and is still made today by Kidde Fire Fighting. The foam is made from soy protein and water, mixed and then aerated in a nozzle. The foam smothers the fire, coating the oil and preventing oxygen from getting to it. Seamen called the mixture ‘bean soup,’ since it was made from soybeans.

National Foam System (today owned by Kidde) got a sample of the soy protein from the Glidden Company in 1941. Glidden employed an organic chemist named Percy Julian, who had devised a way to separate soy protein from soybean meal. Glidden hired Julian in 1936 because of his resume, and because he was fluent in German, having done his dissertation work in Austria. Glidden had just purchased a modern solvent extraction plant from Germany, and needed someone to supervise the extraction of oil from soybeans, and the production of coatings, solvents, and glues from soy products.

Percy Julian was very happy to have the job, having been refused work at DuPont (because when he arrived they realized he was black), and at the Institute of Paper Chemistry (because the town where it was located didn’t allow black residents). Although frustrating, this discrimination was not surprising for Julian, who was well acquainted with Jim Crow. He grew up in Montgomery, Alabama, and went to college at DePauw University, where he was not allowed to room on campus, and had trouble finding a place that would serve him food. He attended Harvard on a fellowship for graduate studies, but left with only a masters degree, because they withdrew his teaching assistantship. They were concerned their undergraduates would not like being taught by an African American.

Julian took up teaching at Howard University, and left when he received a Rockefeller fellowship to finish his graduate studies at the University of Vienna. Ironically, given the rising fascism in Europe, he found freedom from racial prejudices there, like many black artists and intellectuals of the era. After receiving his PhD in 1931 he returned to Howard.

There he got caught up in personal and political controversies, and was forced to resign his position. A former professor at DePauw offered Julian a temporary position in the chemistry department. While at DePauw he worked to synthesize stigmasterol from a west African bean, the calabar. Stigmasterol, extracted from soybean until then, was an important and expensive precursor to steroid hormones. Julian’s discovery of a method for creating stigmasterol from inexpensive raw products was thus a boon to pharmaceutical research. Despite this accomplishment, Percy Julian was denied a professorship at DePauw because he was black. Thus he ended up working in industry at Glidden.

At Glidden, Percy Julian developed many products for paper coatings and glues and paints. During the war some of these were used to coat airplanes and paint ships and boats. Later he was able to produce soy sterols to be used in producing sex hormones. Some of the products he produced were so valuable that they were shipped to manufacturers in armored cars.

When Glidden gave up pharmaceutical work in 1953, Julian left the company and started his own. At the time he was being paid $50,000 a year (about $440,000 in today’s dollars). Percy Julian’s later life was a mixture of success and obstacles. His company was fairly successful, and he was elected to the National Academy of Sciences (in 1973, on the second African American in the Academy). On the other hand, he faced continued discrimination. For example, in 1950, when he moved his family into a ‘nice’ neighborhood in Oak Park, a suburb of Chicago, someone fire-bombed the house on Thanksgiving Day. Later that year someone tossed dynamite into their house.

There is a fine documentary about Percy Julian, produced by PBS’ Nova. Named ‘Forgotten Genius,’ it first aired in 2007.

All images from PBS media

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

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SciTech Tuesday: From Christmas Lights to Proximity Fuses

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During WWII many factories changed their production from peacetime to wartime products. One General Electric factory in Cleveland, OH, went from making Christmas lights to a top-secret electronic device protected by security surpassed only by the Manhattan Project and the D-Day invasion of Normandy.

From 1939-1942 radar researchers in England tested a variety of devices that might be used to improve the effectiveness of anti-aircraft artillery. These artillery cause the most damage when they explode a short distance from their target. Detonation timing was based on a set timer or on impact, neither of which were efficient.

The idea being researched in England was that a small radio transmitter, coupled with an equally small receiver, could be mounted on the nose of a missile. The transmitter’s signal would bounce back, and the interaction of the sent and received signals could be used to estimate proximity to a target. These electronics required a battery, and had to be tough enough to withstand launch. The English called the technology VT, or Variable Timer fuzes. It was later called a Proximity fuse.

The Tizard mission brought the plans and data from these tests to the US, and the NRDC prioritized development and production of the fuses. Some improvements were made, and by 1944 a significant proportion of all US electronics output was parts for Proximity fuses. These were made by many companies, including RCA, Eastman Kodak, and Sylvania, in the the first mass-production of printed circuits.

Julius Rosenberg stole some of this technology and passed it to the Soviet Union. The US military was so concerned about the secrecy of Proximity fuses that they limited its use where German forces might capture unused or unexploded devices.

Vannevar Bush, head of the Office of Scientific Research and Development during the war viewed Proximity fuses as of special importance to Allied success, crediting them with a sevenfold increase in effectiveness in defense against Kamikaze attacks, neutralization of V-1 attacks, and in its use in the Battle of the Bulge against land troops.

The triggers were so sensitive that they occasionally took out unfortunate seagulls. Eventually Proximity fuses were used in bombing Japanese cities, and today’s current weapons use similar principles for detonation.

The Germans had been developing similar technology in the 1930s, but dropped it for other weapons with more immediate promise shortly after 1940.

 

A diagram of the Proximity fuse, published shortly after WWII. From Wikimedia Commons.

A diagram of the Proximity fuse, published shortly after WWII. From Wikimedia Commons.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

 

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SciTech Tuesday: The Battle of the Atlantic

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Seventy five years ago, although the U.S. was not officially engaged in the war, ships under the flag and carrying U.S. goods and passengers were being attacked by German U-boats.

In June 1941 the SS Robin Moor, though carrying no military supplies or personnel, was sunk by U-69 off the coast of Sierra Leone after passengers and crew were given a short time to evacuate on life boats. The U-Boat 552 sank the U.S. naval destroyer USS Reuben James on 31 of October 1941, off the coast of Iceland.

The Battle of the Atlantic began in 1939 when Germany began a blockade of England. The balance of power and nature of the battle changed over the years. With the loss of the French Navy and the occupation of Norway in 1940, England lost an ally and the Germans were able to add to the numbers of U-boats in the Atlantic, and to use French bases to launch ships.

Germany had the upper hand in the long-running battle from June 1940 until early 1941. The British Navy responded by moving to larger and less frequent convoys, and the U.S. added some escorts to defense of cargo ships. England also shared its developments in ASDIC (later called SONAR) and depth charges with the U.S., but there were great limitations to the early technology. The depth charges went only to half the depth the U-boats could dive, and ASDIC could not be used in close proximity to submarines, or at all on surface vessels. In early 1941 the British changed coordination of convoy escorts, and their casualty rate declined. Radar sets that tracked broadcasting submarines further aided the Royal Navy in locating U-boats. In response, Admiral Donitz, who commanded the German U-boat fleet, moved his ‘wolf-packs’ hunting convoys farther west into the Atlantic, in a gap in air support that left the convoys particularly vulnerable.

When, in the middle of 1941, British codebreakers began to reliably translate Enigma codes, the battle swung in the advantage of the Allies, but this reprieve was brief. German production of U-boats overwhelmed that advantage in late 1941 and convoy casualties again began to rise.

When the U.S. entered the war at the end of 1941, Donitz directly targeted the ports of the eastern seaboard. In early 1942 U-boats patrolled the coast of the U.S. and sank over a million tons of cargo without losing a single submarine. As the U.S. began escorting convoys, they pushed the U-boats back into the mid-Atlantic. Convoy losses were large, but not critical at this time.

Through 1942 and 1943 technological advances by the Allies shifted the balance of naval power. The Allies began to use ‘hedgehogs,’ contact-fuzed bombs, and Leigh lights. U-boats ran on batteries will below and surfaced to recharge batteries, replenish air, and attack. They could move much more quickly on the surface than below. The early RADAR systems could not detect at short range, and so the Leigh lights allowed aircraft to spot surfaced U-boats.

Allied losses rose again in the Spring of 1943, as the number of U-boats peaked and the Germans improved the Enigma key, making their code unreadable for a period of a couple of weeks. But further technological advances on the part of the Allies finally decided the Battle of the Atlantic over the Summer of 1943.

There were finally long-range aircraft in place that could hunt and destroy U-boats. Anti-ship modified B-24s based in Newfoundland supported convoys in the mid-Atlantic. Additionally, centimeter-band RADAR technology was deployed on aircraft and ships. This more sophisticated RADAR allowed location of U-boats by ships and planes, and was undetectable by German technology.

The Allies pressed their new advantage, and focused resources on the Bay of Biscay, where the Germans based most of their U-boats. This finally reduced the efficacy of the German U-boat fleet.

Without victory on the Atlantic, it is doubtful the Allies would have been able to move the troops and supplies into position for the invasion of Normandy. In fact, in Spring 1943 there was serious doubt whether England had enough food and supplies to survive even without sending material overseas. Innovation in technology and its deployment won the Battle of the Atlantic.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

all images from the collection of the National WWII Museum.

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SciTech Tuesday: The Armistice Day Blizzard

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You’ve probably seen that video of the Tacoma Narrows Bridge vibrating in heavy winds and then breaking apart. That happened November 7, 1940, less than one year after it opened. The storm producing the 35-45 mph winds that took the bridge down formed off the coast of Washington days earlier, and a few days later killed more than 100 people in the Midwest.

November 11, 1940, was a warm day, in the upper 50s and 60s in the Midwest. It being a holiday (in celebration of the WWI’s armistice) many went out hunting that day. By the end of the day that would change, as a low-pressure system moved up from the southern plains into lower Wisconsin, and Arctic air and wet Gulf of Mexico air fed into the storm on either side.

From Nebraska in the south to Michigan and Minnesota in the north, temperatures dropped by about 50 degrees Fahrenheit, and winds whipped at 50-80 mph. The cold and wet air masses combined to produce up to 30 inches of snow, that piled into drifts 20 feet high. Hunters who left home in light jackets, and were amazed to see so many ducks flying southward, were soon stranded in a blizzard. Roads closed, trains derailed, and phone and telegraph lines were cut, leaving communications down and supplies delayed.

Storm fatalities totaled 145, mostly duck hunters, and sailors on commercial ships on the Great Lakes. An estimated 1.5 million turkeys, planned to be on Thanksgiving tables, died of exposure. It was also the end of the orchards of northern Iowa, where many apples are produced. The cold snap killed almost all the trees, and led farmers to plant crops that wouldn’t take years to come to harvest.

The storm also led to changes in US meteorological systems. Before the storm, all the Midwest forecasts came out of Chicago, and the office operated only during business hours. After the storm, more regional offices were formed, and staffing and forecasting became a 24-hour-a-day business.

Some stranded in trains and ships run aground waited days for rescue. Fuel and food were significantly delayed to the region, and coming late in the Depression this was a serious hardship.

Just over a year before the Pearl Harbor attack, the Armistice Day blizzard had a significant impact on the United States in many ways. It showed the local, state, and federal governments to be lacking in logistics and support of citizens. It also contributed to the anxiety of a population coming out of the Depression and unnerved by the news from overseas.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

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SciTech Tuesday: Percy Spencer and the microwave oven

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Seventy one years ago, on October 8 1945, Percy Spencer filed a patent for a cooking oven powered by microwave radiation. He worked for Raytheon, who owned his intellectual property, so Spencer got a $2,000 stipend but no royalties for his invention.

Percy Spencer, born in rural Maine in 1896, had a very hard early life. His father died before he was 2 years old, and when his mom couldn’t support him after that she left him with an aunt and uncle. That uncle died shortly thereafter. Percy was working in a mill by 12, and as an electrician at 14. He enlisted in the Navy with an interest in radio, and learned there about the science of making and using electromagnetic waves to send information.

By 1939 he was an expert on radar tubes, and was working for Raytheon. Most of the government’s research on radar leading up to WWII was being conducted at MIT’s Radiation Laboratory and Raytheon won the contract based largely on Spencer’s reputation. At Raytheon Spencer developed new manufacturing techniques to build radar tubes much faster.

In 1940 the Tizard mission brought UK radar technology to the US, including a cavity magnetron that greatly improved radar technology. When Spencer was experimenting with magnetrons he discovered that a snack bar he had in his pocket had melted. He was not the first to notice that magnetrons created heat energy, but the next day he was the first to experiment with it. Spencer put a container of popcorn over the magnetron and made the first microwave popcorn. He worked to contain the waves in a metal box and focus their energy.

The first commercial microwave oven was made in 1945, but was very large and expensive. They became smaller and more affordable as the decades passed.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

A Raytheon Radarange from the 1950s

A Raytheon Radarange from the 1950s

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