AVIATION HISTORY Lecture 9: Speeds of Flight

Mach Number  Speed of sound:  How fast the sound waves travel.  At sea level, 760 miles per hour (mph)  Speed of sound decreases as the altitude increases  Mach number are used to show the pilot’s speed in comparison to speed of sound.

Speeds of Flight  Speeds of flight can be classified based on Mach Numbers to 4 categories:  Subsonic  Transonic  Supersonic  Hypersonic

Subsonic  Aircraft speeds which are very much less than the speed of sound  The Mach number M is much less than one, M << 1.  2 categories: 1. Medium Speed ( mph)  Small planes such as crop dusters and seaplanes are examples of planes that travel at this speed 2. High Speed ( mph)  Most of the commercial aircrafts that are used for passenger & cargo

Transonic  Aircraft travelling between Mach 0.8 and Mach 1.0 (0.8<M<1.2) Supersonic  Flying faster than the speed of sound. Faster than Mach 1 (1.2<M<5.0).  Majority supersonic aircraft designed for high speed aircraft, military & experimental.  Example: Concorde

Hypersonic  Greater than Mach 5. This is more than five times the speed of sound.  It is the speed traveled by rockets and the space shuttle as they go into orbit.

Supersonic Military: SR-71 Blackbird  Role: Strategic Reconnaissance  Primary users: United States Air Force NASA  The world's fastest aircraft.  Advanced, long-range, Mach 3  Was in service from 1964 to 1998  Number built: 32

SST: Supersonic Transport  A Supersonic Transport (SST) is a civil aircraft designed to transport passengers at speeds greater than the speed of sound.  The only SST to see regular service was the Concorde, and the only other design built in quantity was the Tupolev Tu-144.  The last passenger flight of the Tu-144 was in June 1978, and the Concorde's last flight was on 26 November  As of 2005, there are no more SSTs used in regular commercial service.

British-French Concorde SST  Manufacturers: BAC (now BAE Systems), EADS.  Introduction: 21 January 1976  Retired: 26 November 2003  Primary users  British Airways  Air France  Number built: 20  Unit cost: £23 million in 1977

Fastest Commercial Aircraft: Concorde

Advantages of Supersonic Aircraft  High Speed  Double-delta shaped wings- to gain more lift.  Droop-nose section for improved visibility in landing  Weight Saving  Aircraft skin was made from Aluminium  Fully electrically controlled fly-by-wire flight controls systems

Explain the reasons why airliners have failed to go supersonic?

Factors about airliners have failed to go supersonic 1. High operating costs – high fuel consumption 2. Takeoff noise – environmental issues 3. Poor range – uneconomical 4. Aerodynamics – airframe design 5. Structural issue 6. Need to operate aircraft over a wide range of speed

High operating costs  High fuel consumption, thus higher ticket costs. Low passengers demand.  Lower passenger capacities due to the aerodynamic requirement for a narrow fuselage.  Both Concorde and the Boeing 747 use approximately the same amount of fuel to cover the same distance, but the 747 can carry more than four times as many passengers.

Takeoff noise  High engine noise levels, associated with very high jet velocities used during take- off, disturbing communities near the airport.  This is an environmental hazard – Noise pollution

Poor range  Range means how far can the aircraft fly with a tank of fuel.  SST can only carry lesser fuel due to airline trying to increase passenger volume  This means that SST can not cover many routes.

Aerodynamics (Drag increases)  The faster the speed the higher the air resistance, thus the higher the drag.  As the drag increases, more power/fuel require to overcome the drag which lead to high fuel cost.

Structural issues  SST speeds demand narrower wing and fuselage designs, thus are subject to greater stresses and temperatures.  SST also require a much stronger (and therefore heavier) structure to operate at the high altitudes.

Need to operate aircraft over a wide range of speeds  The aerodynamic design of a supersonic aircraft needs to change with its speed for optimal performance. Thus, SST would ideally change shape during flight to maintain optimal performance at both subsonic and supersonic speeds – e.g. swing wing  Such a design would introduce complexity which increases maintenance needs, operations costs, and safety concerns.

Aircraft Types Military Aircraft: Swing Wings of F-14 Tomcat fighter Passenger/ Cargo Aircraft Airbus A380 V/STOL( Vertical and short take- off and landing) Aircraft

Aircraft Utilization  Military  Fighters  Transport  Helicopter  Reconnaissance  Private Aircraft  VIPs Personal  Crop spraying  Airlines  Passengers  Cargo

Aircraft Types Tilt Rotor plane’s Business Jets

Military  Fighter: Detecting & attacking enemy targets  Air to air missiles/guns  Air to ground: Bombs, Missiles  Supplying weapons to other aircraft  Transport: Soldiers, VIP/VVIP  Helicopters with rapid fire machine guns  Reconnaissance  Air to air refueling Sidewinder AIM-9 Missile Military Helicopter Refueling an airplane in mid-air

Military aircraft Black Widow World’s Smallest Spy Aircraft Northrop B-2 Stealth Bomber Observation Aircraft

Private Aircraft  Light aircraft owned or rented by the pilot.  Used for a wide range of commercial tasks, such as flight training, passenger and freight transport, policing, crop spraying and medical evacuations. Crop SprayingMedical Evacuations