Abstract: An embodiment of the present invention is a gas turbine engine including a compressor, a turbine, an annular combustor, an exhaust duct, a first engine shaft bearing, and a second engine shaft bearing. The turbine has an axial flow direction toward the compressor. The combustor has an axial flow direction away from the compressor. The exhaust duct is disposed between the compressor and the combustor. The first engine shaft bearing is disposed on an axial side of the compressor opposite the turbine. The second engine shaft bearing is disposed on an axial side of the turbine opposite the compressor.

Abstract: A load compressor includes an air inlet and an outlet, and a surge control valve positioned on the outlet. The surge control valve serves to selectively pass air to a downstream use, or to be dumped to atmosphere. A control for the compressor and the surge control valve is also included. The control is provided with a variable indicative of the operation of the load compressor, the variable being indicative of a movement to transient operation of the compressor. The control is provided with a low surge control limit for steady state operation. The control is also provided with a higher surge control limit, and switches to use of the higher surge control limit if the variable being monitored is seen to change beyond a particular threshold. The low and higher surge control limits are utilized to control the opening of the surge control valve. An aircraft air supply system and a method are also disclosed.

Abstract: A radiation probe includes an optionally cooled tube 10 with a window 22 at one end, and can be traversed across a gas turbine engine combustion chamber 20 by drive means 26. A radiation detector 28 simultaneously measures radiation intensity at a plurality of wavelengths, at each of a succession of positions during the traverse. From this data, local values of radiation levels, grey and non grey absorption coefficients, local temperature and local gas composition and soot concentration are calculated, using a recurrence formula which relates intensities at neighboring positions.