Supersonic aircraft transport

Control of nitrogen oxides ia aircraft exhaust is of increa sing concern because nitrogen oxides react with ozone ia the protective layer of atmosphere which exists ia the altitude region where supersonic aircraft operate. Research is under way to produce a new type of combustor which minimizes NO formation. It is an essential component of the advanced propulsion unit needed for a successflil supersonic transport fleet. 

Weaver, C. J., A. R. Douglass, and D. B. Considine, A 5-Year Simulation of Supersonic Aircraft Emission Transport Using a Three-Dimensional Model, J. Geophys. Res., 101, 20975-20984 (1996). 

Abstract. The impact of future aircraft emissions on concentrations of reactive nitrogen, water vapour and ozone has been calculated using the 3-dimensional stratospheric chemical transport model SCTM-1. Emissions of NOx (N0+N02) and H20 from both sub- and supersonic aircraft have been considered. 

Wallace (1975) calculated absorbed doses to passengers for a round trip, for both subsonic and supersonic transport between various city pairs. Some of these estimates are shown in Table 3.8. Doses for a round trip in supersonic aircraft are approximately 70% of those for subsonic speeds, because of the shorter flying time. However, the dose rates in supersonic aircraft are about twice as high as in subsonic aircraft. For a round trip across the Atlantic, the tissue-absorbed doses in passengers may be estimated to be about 2 10" Gy for an SST and 3 10 Gy for a subsonic aircraft, under average solar conditions. 

One possible agent of inadvertent stratospheric modification is NO, emitted by supersonic transport aircraft. As discussed in Subsection 3.4.3 NO, takes part in photochemical processes in the stratosphere in such a way that it catalyzes the reaction of O and 03 molecules (see also Fig. 9). That this reaction occurs was confirmed in individual cases by measuring the vertical profile of 03 over an area (Berlin) where supersonic transport is heavy (Grasnick, 1974). It is much more difficult, however, to assess long-range global effects. One estimate (Rowland, 1976) states that if 100 supersonic aircraft of models available at present were operated, the increase in ultra-violet radiation erythermally effective would be 0.04 % at the... 

A4. Crutzen, P.J., 1972 The Photochemistry of the Stratosphere with Special Attention Given to the Effects of NOx Emitted by Supersonic Aircraft , First Conference on CIAP, United States Department of Transportation, 80-88. 

Equation 25 represents the reaction responsible for the removal of uv-B radiation (280—330 nm) that would otherwise reach the earth s surface. There is concern that any process that depletes stratospheric o2one will consequently increase uv-B (in the 293—320 nm region) reaching the surface. Increased uv-B is expected to lead to increased incidence of skin cancer and it could have deleterious effects on certain ecosystems. The first concern over depletion was from NO emissions from a fleet of supersonic transport aircraft that would fly through the stratosphere and cause reactions according to equations 3 and 26 (59) ... 

The first commercial supersonic transport, the Concorde, operates on Jet A1 kerosene but produces unacceptable noise and exhaust emissions. Moreover, it is limited in capacity to 100 passengers and to about 3000 miles in range. At supersonic speed of Mach 2, the surfaces of the aircraft are heated by ram air. These surfaces can raise the temperature of fuel held in the tanks to 80 °C. Since fuel is the coolant for airframe and engine subsystems, fuel to the engine can reach 150°C (26). An HSCT operated at Mach 3 would place much greater thermal stress on fuel. To minimize the formation of thermal oxidation deposits, it is likely that fuel deflvered to the HSCT would have to be deoxygenated. 

Perhaps the biggest thrust for the development of high performance polymers over the next 10 years will be in the aerospace industry where materials will be required for a fleet of high speed civil transports (supersonic transports). At a speed of Mach 2.4, an aircraft surface temperature of about 150 to 180°C will be generated. The life requirement of materials at these temperatures will be about 60000 hours. Many different types of materials such as adhesives, composite matrices, fuel tank sealants, finishes and windows will be needed. These materials must exhibit a favorable combination of processability, performance and price. The potential market for these materials total several billions of US dollars. 

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