Cranfield Institute of Technology - Memoranda (1970- 1974)
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Item Open Access Aeroplane design study STOL airliner (A71). Part 3- low speed lift and control(Cranfield Institute of Technology, 1972-06) Ward, R. E.The potential application of advanced forms of aircraft control to civil operation appears to be capable of being split into two areas. First, those aircraft which are very large, whose rotary inertia tends to reduce the effectiveness of conventional controls. Second, those aircraft whose specification dictates that the aeroplane be flown at very low speed. Again conventional controls become inefficient due to decreased aerodynamic efficiency. The second category of aircraft has been considered in the form of an STOL aircraft. The control problems of an STOL aircraft with a 2000 ft runway capability (Ref.10) have been examined. It has been found that the aircraft is unstable and could require autostabilisation. None of the conventional controls were satisfactory and each required augmentation. The single strip crosswind requirement penalises the design most heavily since this requires over half of the extra control power necessary. The total augmentation for blowing air amounts to an equivalent thrust of approximately 6700 lb. This is equivalent to 11.5 per cent of the total installed aircraft thrust.Item Open Access A preliminary study of survival rates in civil aircraft accidents, 1966 - 1973, with particular reference to fire risk and fuel type(Cranfield Institute of Technology, 1974-03) Taylor, A. F.To establish whether theoretical and laboratory safety advantages of low volatily fuel, such as that of low rate of flame spread, are reflected in aircraft accident 'statistics' a preliminary study has been made of the ARB's world airline accident summary. An advantage has been found in that the change to kerosine has apparently halved the death rate in survivable accidents. In all gas turbine accidents, including those where death was probably due to impact not fire, the death rate seems to be 50% higher with wide cut gasoline than with kerosine. It has also been found that a higher proportion of gasoline powered aircraft accidents involved impact death 1.1-1d that overall the survival rate has remained virtually unchanged. A critical examination of these preliminary findings, in the light of the relevant accident reports, is planned.Item Open Access The influence of flow parameters on minimum ignition energy and quenching distance(Cranfield Institute of Technology, 1974-04) Lefebvre, Arthur H.; Ballal, Dilip R.Experiments have been carried out on the effects of pressure, velocity, mixture strength, turbulence intensity and turbulence scale on minimum ignition energy and quenching distance. Tests were conducted at room temperature in a specially designed closedcircuit tunnel in which a fan was used to drive propane/air mixtures at subatmospheric pressures through a 9 cm square working section at velocities up to 50 m/s. Perforated plates located at the upstream end of the working section provided near-isotropic turbulence in the ignition zone ranging from 1 to 22 percent in intensity, with values of turbulence scale up to 0.8 cm. Ignition was effected using capacitance sparks whose energy and duration could be varied independently.