The RAF 11 Group rose to meet them in greater numbers than the "Luftwaffe" expected; 12 Group's Big Wing took 20 min to gain formation and missed its intended target, but it came across another formation of bombers while it was still climbing. It returned, felt sorry about their limited success and blamed the delay on being requested too late.
The "Luftwaffe" began to abandon its morning raids, with attacks on London starting late in the afternoon for 57 nights of attacks in a row.
Fighter Command had been suffering low morale since it was short of men and machines, and the break from airfield attacks allowed it to recover and so week by week, the defenders were getting stronger, and the losses suffered by the "Luftwaffe" were growing.
On 15 September, two massive waves of German attacks were prevented by the RAF, with every aircraft of 11 Group being used that day. The total casualties on that important day were 60 German and 26 RAF aircraft shot down. The German defeat caused Hitler to order two days later a delay of the preparations for the invasion of Britain. In the face of increasing losses in men, aircraft and the lack of good replacements, the "Luftwaffe" later switched from daylight to night-time bombing.
On 27 September, a Junkers Ju 88 returning from a raid on London was shot down in Kent. The German airmen survived to fight a battle against British troops stationed locally. That was said to be the first time in nearly 300 years that armed invaders had fought with British soldiers on British soil.
The keystone of the British defence was the detection, command, and control, which ran the battle. It was called the 'Dowding System', after its chief architect, Air Chief Marshal Sir Hugh Dowding, the leader of RAF Fighter Command.
The core of the system was the use of Radio Direction Finding (RDF, later called radar, for radio detection and ranging). Its use, as we as by information by the Royal Observer Corps, was crucial and allowed the RAF to intercept the incoming German aircraft.
Radar operators were linked via telephone, whose wires were laid deep underground with concrete anti-bomb protection, to an operational centre. The centre was Fighter Command Control at Bentley Priory. During the battle, several Coastal Command and Fleet Air Arm units came under Fighter Command control.
The Germans' Messerschmitt Bf 109E and 110C squared up against the British workhorse Hawker Hurricane Mk I and the less numerous Supermarine Spitfire Mk I. The Bf 109E had a better climb rate and was 10 to 30 mph faster than the Hurricane, depending on the altitude. In September 1940, the more powerful Mk IIa series 1 Hurricane started entering service but only in small numbers. That version was capable of a maximum speed of 342  mph, 25 to 30  mph faster than the Mk I.
The performance of the Spitfire during the Dunkirk evacuation came as a surprise although the German pilots retained a strong belief that their 109 was the superior fighter. However, the Bf 109E had a much larger turning circle than either the Hurricane or the Spitfire. The two British fighters had eight Browning 303 machine guns, but most Bf 109Es had two machine guns and two wing cannons. The Bf 109E and the Spitfire were superior to each other in key areas. For instance, at some altitudes, the Bf 109 could outclimb the British fighter.
The failure of Germany to achieve its objectives of destroying Britain's air defences or forcing Britain to negotiate an armistice or an outright surrender is considered to be its first major defeat and one of the crucial turning points in the war.
If Germany had gained air superiority, Adolf Hitler might have launched Operation Sea Lion, a planned amphibious and airborne invasion of Britain.
Thermite
Thermite is an incendiary mixture. It is not an explosive material, but can burn very fast and very hot.
It is made of an oxide of a less reactive metal mixed with a more reactive metal. One of the most common mixtures is iron(III) oxide-aluminium. The iron(III) oxide oxidizes the aluminium, being reduced to iron in the process. The aluminium is oxidized to aluminium oxide.
Many other metal oxides and metals can be used for thermite. Some metals that can be used are boron, magnesium, calcium, titanium, zinc, or silicon. Some metal oxides that can be used are copper(II) oxide, chromium(III) oxide, iron(II,III) oxide, manganese(IV) oxide, silicon dioxide, boron trioxide, or lead(II,IV) oxide. A metal cannot be used with its metal oxide. The metal has to be more reactive than the metal in the oxide, or the thermite will not work.
The reaction for an aluminium-iron(III) oxide thermite is this:
It is difficult to ignite thermite. It needs to be very hot. Ribbons of magnesium metal are used. A mixture of potassium permanganate and glycerin can be used to ignite thermite. It can be ignited by a flint lighter or a child's sparkler. It can be mixed with sulfur to make thermate, which makes it easier to melt the iron.
Contrary to popular opinion, metals can burn. Common metals need to be powdered, though, or they will conduct the heat away too fast to start a fire.
The thermite ("thermit") reaction was discovered in 1893. German chemist Hans Goldschmidt patented it in 1895. People called it the "Goldschmidt reaction" or "Goldschmidt process". Goldschmidt was trying to make very pure metals without the use of carbon in smelting. He soon discovered the value of thermite in welding. It started to be used in the early 1900's to weld train tracks.
Thermite is used for its original purpose, welding railroad rails together. It is also used to weld wires. Thermite is also used to make some metals. Chromium can be made by a thermite reaction between chromium(III) oxide and aluminium. The first uranium was made by a thermite. Thermite may also be used in fireworks to ignite other incendiaries.
Thermite was used in the military as an incendiary weapon. It is mainly used to destroy buildings and equipment as it melts the metal easily. Barium nitrate can be added to thermite to make an easier-burning mixture. Especially during World War II, militaries dropped thousands of bombs containing thermite on cities, starting fires everywhere.
Thermite is not safe to make at home. It releases ultraviolet light which can damage the eyes. It also makes a very hot flame that can melt iron. It is extremely difficult to extinguish. Streams of molten iron can flow out of a thermite mixture, igniting everything it touches. Some metals can boil and burst into flames when placed in thermite, such as zinc. If it is preheated then ignited, thermite can burn very fast, releasing a huge amount of heat and light. If it is dropped in water it can boil water very fast, making an explosion. Dropping it on ice can make the ice explode, however it is safe to drop it into a three liter beaker filled with lightly moist sand.
Boulder, Colorado
Boulder is a city in the state of Colorado, in the United States. It is the county seat of Boulder County. Boulder is in the foothills of the Rocky Mountains. The city's height is . It is northwest of Denver. In 2011, there were 98,889 people living the City of Boulder. The Boulder Metropolitan Statistical Area has 294,567 people living in it.
Boulder is famous for its history and its Western traditions. In the late 1960s, lots of hippies moved to Boulder. The main campus of the University of Colorado, the University of Colorado at Boulder, is also here. CU Boulder is the biggest university in Colorado. The city is thought to be one of the best cities for health, well-being, quality of life, education, and art.
On November 7, 1861, the government decided to build a university in Boulder. The legislature decided that the university would be run by the state. The first building was built in 1875. The cornerstone for the Old Main Building was laid on September 20, 1875. The university was officially opened on September 5, 1877.