996,166. Auxiliary power installations on aircraft. NORMALAIR Ltd. Sept. 23, 1963 [Oct. 11, 1962], No. 38484/62. Heading B7G. A unit providing a combined cooling and electricity generating system for aircraft includes, in combination, a ram air inlet, a ram air driven power turbine and a ram air driven turbo compressor, the power turbine and the turbo compressor being connected in parallel to the ram air inlet, the ram air driven power turbine driving electricity generating means and the ram air driven turbo compressor, in combination with heat exchange means, forming a reversal bootstrap unit. The apparatus, which is intended to be installed in a wing-tip pod, comprises a ram-air intake 1 which beyond a diffuser 1 divides into two annular intakes 3, 3a. Air entering intake 3a passes stators 8 which are adjustable in area by an hydraulic ram 12 controlled by a valve 14 responsive to a governor 15 driven by a power turbine 7 which in turn drives an electrical generator 9 for supplying current to apparatus within the aircraft. Air entering intake 3 passes through a single or multi-stage cooling turbine 4, heat exchanger 5 and compressor 6, the coolant from heat exchanger 5 passing through conduits 11 to cool the apparatus to which the generated electricity is supplied or to other equipment such as de-icing apparatus. Air cooled by expansion through turbine 4 is conducted at 17 and 18 to a voltage regulator 19 and to generator 9 respectively. Temperature control is provided by a thermostatically controlled valve 16 in the conduit system of coolant 11.