The Supersonic Age: Lightning & Concorde

Transcription

1 The Supersonic Age: Lightning & Concorde Orville Wright made the first powered flight in 1903: it lasted for 12 seconds and since that time humans have been fascinated by flight at speed. Think about R J Mitchell and his success in winning the Schneider Trophy and then his work in developing Spitfire. The conquest of flight at speeds faster than sound is truly a marvel of the modern world. In its way it is as wonderful as the Pyramids, the early voyages of discovery, or the development of penicillin. Make a list of the things that you find really amazing. In 1949 a team of talented designers at a company called English Electric started work on the first British aircraft designed for supersonic flight: The Lightning. To ensure the safety of this country, The British Government needed a jet fighter plane, which could climb quickly to destroy enemy bomber aircraft and which was at least as quick as any enemy s fighter planes. The name Lightning captures the idea of something moving faster than the speed of sound. If you were to design a supersonic fighter, what would you call it? 1

2 Flying supersonically means flying faster than the speed of sound. In order to do this it will need to overcome drag, so let s try to understand some basics first... Forces operating on an object in flight. With a group of friends, look at the following information about flight. Working together try to devise an experiment or series of tests which you can show to the rest of your class demonstrating why objects can fly. There are four main forces which operate on an object flying through the air: thrust; weight; lift; drag. The weight of an object moving through the air is important. If it is heavy, then it will need greater power behind it to make it travel: this is called thrust therefore the amount of thrust controls the speed at which an object can travel. The shape of the object is also important; if it has wings and in cross-section those wings are a shape called an aerofoil then those wings will create lift, as it travels through the air. Imagine the difference in shape between a glider and a brick! Drag is best described as wind-resistance or friction as the object passes through air: this force will slow down an object passing through the air. The shape of the object is central to the amount of drag that is created; imagine the difference in aerodynamics between a cricket ball and an arrow. To Summarize... To succeed in making our object fly, it needs sufficient thrust and sufficient lift to overcome the other two forces, weight and drag which would make it fall to earth. Thrust Lift Drag Weight Forces acting on a wing Helpful Hint: To help you devise your experiments, you might like to think about the difference in aerodynamics between a cricket ball, a football, an arrow, a brick and a glider. 2

3 It s such a drag. Work out how an aircraft responds to travelling faster than the speed of sound by filling in the missing words from the list below. An aircraft in flight can be flying below the speed of sound and that is called (1) On its way to travelling supersonically (faster than the speed of sound) it is described as flying (2). When an aircraft s speed is the same as the speed of sound it is said to be travelling at Mach 1. As any aircraft flies, it experiences (3)... from the air, which we also call (4)... An aircraft in flight separates the air, much like a boat does when travelling through still water. The airflow over the top of the aircraft has to travel over parts that stick out or up, like the (5)... whereas the airflow that passes the underside of the aircraft is smoother. At speeds below (6)... the airflow behaves like water, but above this speed, the air has less time to prepare itself to be separated and behaves (7)... much more like a wave. This new way of air behaving created (8)... which we referred to as the sound barrier. As a supersonic aircraft such as (9)... or (10)... passes through the air, the turbulent air wants to revert to its original condition. It does this quickly, producing (11)... which we can hear on the ground underneath as a boom. The disturbance which these cause can be great enough to (12)... buildings and so supersonic flight paths do not cross populated areas! resistance transonically mach 0.75 shock waves drag lightning damage subsonically drag concorde cockpit differently Warton Salmesbury Farnborough Because of the sonic waves or boom generated by supersonic aircraft, it s a good idea to fly them over the sea! 3

4 The first British supersonic flight didn t take place in a Lightning but in a de Havilland DH108, by John Derry in How could that have happened in an aircraft that was not designed for supersonic flight? How might that have been dangerous? What do you notice about the difference in size and shapes of the different aircraft civil and military which informed the design of Concorde? The technology and expertise that went into making The Lightning was later used to develop Concorde, the only supersonic civil airliner which was designed to make flights around the world much quicker! Although the supersonic technology was the same, the purposes of the aircraft were very different and required different ways of thinking and of designing the on-board systems. Write down how these systems might be the same or different. Electrics Passenger Navigation Undercarriage Flying controls Pressure Weapons Fuelling Safety Accommodation Braking Landing 4

5 Add your own caption in the space above