Supersonic aircraft
[1] According to David Masters,[2] the DFS 346 prototype captured in Germany by the Soviets, after being released from a B-29 at 32800 ft (10000 m), reached 683 mph (1100 km/h) late in 1951, which would have exceeded Mach 1 at that height.
On August 21, 1961, a Douglas DC-8-43 (registration N9604Z) exceeded Mach 1 in a controlled dive during a test flight at Edwards Air Force Base.
[3] In the 1960s and 1970s, many design studies for supersonic airliners were done and eventually two types entered service, the Soviet Tupolev Tu-144 (1968) and Anglo-French Concorde (1969).
In particular, aerodynamic drag rises sharply as the aircraft passes the transonic regime, requiring much greater engine power and more streamlined airframes.
Most subsonic designs use aluminium alloys such as Duralumin, which are cheap and easy to work but lose their strength quickly at high temperatures.
Supersonic jets and rocket vehicles require several times greater thrust to push through the extra aerodynamic drag experienced within the transonic region (around Mach 0.85–1.2).
Duralumin, a material traditionally used in aircraft manufacturing, starts to lose strength and deform at relatively low temperatures, and is unsuitable for continuous use at speeds above Mach 2.2 to 2.4.
For example, the Lockheed SR-71 Blackbird jet could fly continuously at Mach 3.1 which could lead to temperatures on some parts of the aircraft reaching above 315 °C (600 °F).
The shock waves are positioned using a ramp or cone which may need to be adjustable depending on trade-offs between complexity and the required aircraft performance.
An aircraft that can accelerate past this speed sees a significant drag decrease, and can fly supersonically with improved fuel economy.
However, due to the way lift is generated supersonically, the lift-to-drag ratio of the aircraft as a whole drops, leading to lower range, offsetting or overturning this advantage.
This has led to almost every supersonic cruising aircraft looking very similar to every other, with a very long and slender fuselage and large delta wings, cf.
In the 1960s and 1970s, many design studies for supersonic airliners were done and eventually two types entered service, the Soviet Tupolev Tu-144 (1968) and Anglo-French Concorde (1969).
[6] Sonic booms due to large supersonic aircraft can be particularly loud and startling, tend to awaken people, and may cause minor damage to some structures.
Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle the nuisance due to them may be reduced to the point that overland supersonic flight may become a practical option.
Many well known supersonic military aircraft not capable of supercruise can only maintain Mach 1+ flight in short bursts, typically with afterburners.
Due to its long service as a commercial airliner, Concorde holds the record for the most time spent in supercruise; more than all other aircraft combined.
A key feature of these designs is the ability to maintain supersonic cruise for long periods, so low drag is essential to limit fuel consumption to a practical and economic level.
The sharply swept leading edge causes the air to twist as it flows over the wing, speeding up the airflow locally and maintaining lift.
Projects for both large-scale and business jet (see lower) passenger supersonic and hypersonic airliners (Aerion SBJ, Spike S-512, HyperMach SonicStar, Next Generation Supersonic Transport, Tupolev Tu-444, Gulfstream X-54, LAPCAT, Reaction Engines LAPCAT A2, Zero Emission Hyper Sonic Transport, SpaceLiner, etc.)
Typically the aircraft will cruise subsonically for most of its flight to conserve fuel, before accelerating to supersonic speed for its bombing run.
They make up the overwhelming majority of supersonic aircraft and some, such as the Mikoyan-Gurevich MiG-21, Lockheed F-104 Starfighter and Dassault Mirage III, have been produced in large numbers.
Many military supersonic fighters and similar aircraft of fourth- and fifth- generations are under development in several countries, including Russia, China, Japan, South Korea, India, Iran and the United States.
