Rocketry and Atomic Weapons Week 4 World War

Rocketry and Atomic Weapons Week 4 World War 2 Tech

Ancient “Rockets” • Wooden Pidgeon – (Ancient Greece 400 BC) • Earliest known rocket • propelled by shooting out of steam vent • Aeolipile (100 BC) • Sphere shaped rapidly rotating kettle • Had 2 L shaped spouts that expelled steam

First True Rockets • Unknown when first flight was • Fire Arrows – Chinese rockets, tubes of gunpowder, first rockets used in warfare • Chinese repelled Mongol invaders with waves of fire arrows in 1232 AD • Mongols later produced their own and spread the technology to Europe

Multi Stage Rockets • Step Rockets – 1 st Multi Stage Rocket (1600 s) • Large sky rocket - lift off and get to altitude • smaller sky rocket - took it even higher • Basis for all modern rockets for space travel

Congreve Rockets (British) • Used in War of 1812 • Inspiration for the Star Spangled Banner • Still were mostly inaccurate and had to rely on just sending over many rockets hoping some would hit, eventually improved artillery made them obsolete

Father of Modern Astronautics (Tsiolkovsky) • First recommended liquid fueled rockets • Theorized that the speed and range of a rocket was only limited by the exhaust velocity of escaping gases.

Father of Modern Rocketry • Robert Goddard • Achieved 1 st liquid propelled rocket flight (1926) • Developed a payload compartment for scientific instruments, gyroscopic flight control, and parachutes for safe recovery

Herman Orberth • Wrote highly influential book about rocket travel to outer space • Lead to the development of rocket societies around the world • One German group led to the development of the V 2

Werner Von Braun • Director of German Rocket Program that built V 2 • Came to the United States after the war and essential for the developments of rockets for the US Space Program • His design led to the Saturn V rocket.

V 2 Rocket • 1 st ballistic missile • 1 st artificial object to reach outer space • Formidable weapon that had a tremendous psychological effect • Could devastate whole city blocks • 5, 200 were eventually built using forced labor from prison camps

Design • Aerodynamics designed for supersonic travel • High flow turbopumps for increased fuel pressure • 4 controllable Graphite Rudders for steering • Burned a ton of mixed liquid oxygen and alcohol every 7 seconds

Guidance System • Used tremendous thrust for about 65 seconds to reach the top of a parabolic flight path (about 80 Km) then would glide freefall to target • Had simple analog computer that would adjust heading • Amount of fuel would determine distance • Later ones controlled by radio guide beams • Also further improved by developing full radio control

Limitations • Not very accurate/tactical weapon • Detonators would sometimes go off on reentry to atmosphere • British designed jammers for radio guide beams • Very expensive to build • Not readily available until late in the war (too late)

Meillerwagen • Germany designed a mobile launcher for the V 2 • Built because of the success of Allied bombing raids against launch sites • Very small and could launch anywhere

The Atomic Bomb

Manhattan Project • Joint Project of the US, Canada and England that developed the first atomic bomb. • Began in 1939 2 years before US entered war when Allies became concerned Germany would develop bomb • Employed 130, 000 people in the 3 countries at 30 sites

Discovery of Nuclear Fission • Hahn and Strassman bombarded uranium with neutrons splitting Uranium (1938) • Led to atomic age • They didn’t understand their results but a colleague living in exile in Sweden (Lise Meitner) figured it out and wrote a paper explaining theory of fission

Nuclear Fission • Splitting of a very large atom into smaller ones • Produces free neutrons and photons (gamma ray form) and releases a very large amount of energy. • Neutron is shot at a very large atom splitting the atom and releasing more neutrons that strike more atoms splitting them, this reaction builds and builds causing a chain reaction.

Uranium • Heaviest naturally occurring element known before war • Isotopes are different versions of same element (different numbers of neutrons) • Rare Isotope Uranium 235 seemed to work best • 1000’s of new large high velocity centrifuges were needed • First work was separating and concentrating it because it is only 0. 7% of naturally occurring Uranium)

Plutonium • Replaced Uranium later and used for Fat Boy (2 nd Bomb) • Discovered in 1940

Chicago Pile 1 • First self sustaining nuclear chain reaction • 1 st achievement of Manhattan project • Very low energy and unshielded • Big step because it showed that uranium neutrons would have enough energy to make split other uranium • Experiment led by Enrico Fermi Italian Physicist and University of Chicago

X 10 Graphite Reactor (Oak Ridge Tenn) • 2 nd Reactor • Air Cooled • Became a plutonium factory for the war • Gave valuable experience to the engineers and physicist for the Hanford Site

Hanford Site • B Reactor – 1 st full scale plutonium reactor • Eventually 9 reactors where also built here • Most of the fuel for the US’ cold war nuclear arsenal produced here

Fission Reactors • Heat of reaction is used to heat water and generate steam, steam drives an electric turbine, generating power. • Nuclear chain reaction is controlled by absorbing the flying neutrons with neutron absorbing cooling rods inserted into reactor core when the reactors start to get hot. • Meltdown occurs if the reactor gets too hot to control with the cooling rods.

Fission Bombs

Gun Type Fission Bomb (Little Boy) • 1 st atomic bomb • Dropped on Hiroshima • Secondary TNT detonation (non nuclear) propels neutrons into concentrated U 235 Atoms • Starts chain reaction

Implosion Type Fission Device (Fat Man) • 2 nd Atomic Bomb • Explosion around plutonium center triggers it to get denser and smaller and achieve critical mass • Much more efficient use of bomb material

Trinity Site • In July 1945, Allied scientists tested the first atomic bomb in New Mexico. • Used to test the implosion trigger because it was so complex

Harry S. Truman (1884 -1972) • Became president when President Roosevelt unexpectedly died on April 12, 1945. • He issued warning to Japan to surrender or face “utter and complete destruction. ” • After refusal, Truman authorized the use of the atomic bomb

Reasons for using the bomb • Saved many American lives that would have been lost in an invasion of Japan. • Quick end to the war. • U. S. wanted to test the weapon’s effectiveness. • US wanted to impress the Soviet Rival

The United States drops the Bomb! • On the morning of August 6, 1945, at 8: 15, the B 29 bomber Enola Gay dropped an atomic bomb, Little Boy, on Hiroshima. • Having heard nothing from the Japanese government, the U. S. military proceeded with its plans to drop a second atomic bomb, Fat Man, on Nagasaki on August. 9 th. Enola Gay Crew Little Boy & Fat Man

Hiroshima – August 6, 1945 ü 70, 000 killed immediately. ü 48, 000 buildings destroyed. ü 100, 000 s died of radiation poisoning & cancer later.

Diorama of Hiroshima: Before and After

Nagasaki – August 9, 1945 § 40, 000 killed immediately. § 60, 000 injured. § 100, 000 s died of radiation poisoning & cancer later.

“I realize the tragic significance of the atomic bomb. . . It is an awful responsibility which has come to us. . . We thank God that it has come to us, instead of to our enemies; and we pray that He may guide us to use it in His ways and for His purposes. ” - President Harry Truman, August 9, 1945

Japan Surrenders • Aug. 10 th; one day after the second bomb had been dropped. • On August 29, 1945 U. S. General Mac. Arthur became the leader of Japan from 1945 until 1948. • The United States helped rebuild Japan, even after dropping the bomb!

V-J Day in Times Square From The Eye of Eisenstaedt: “I was walking through the crowds on V-J Day, looking for pictures. I noticed a sailor coming my way. He was grabbing every female he could find and kissing them all — young girls and old ladies alike. Then I noticed the nurse, standing in that enormous crowd. I focused on her, and just as I'd hoped, the sailor came along, grabbed the nurse, and bent down to kiss her. Now if this girl hadn't been a nurse, if she'd been dressed dark clothes, I wouldn't have had a picture. The contrast between her white dress and the sailor's dark uniform gives the photograph its extra impact. ” This photo became a cultural icon overnight!

Aftermath • Nuclear weapons are considered “weapons of mass destruction”, and their use and control has been a major focus of international relations since their debut. • The only countries known to have detonated nuclear weapons are the United States, the Soviet Union/Russia, Great Britain, France, China, India, Pakistan, and North Korea. • The USA is still the only country to have used a nuclear bomb

Heroshima Bombing Reenactment

Nagasaki Bombing Reenactment