The cylinder heads of the Bristol Mercury had to be kept within a range of 190-210 degrees centigrade; too cool and the engine would not respond properly to throttle movements, while too hot would promote detonation in the cylinders: oil temp between 70-80 degrees, with a pressure of 80 psi. Take off procedure in real Blenheims:
Carburettor Air intake Control to "Cold" or "Hot" depending on ambient temperature:
Mixture controls to "Normal":
Prop Pitch to "Fine":
Engine cooling gills to fully open during taxying, but wound closed immediately before take-off, otherwise the drag of the gills could make the take-off run excessively long:
Raise undercarriage immediately after the wheels leave the ground to reduce drag.
The Bristol Mercury XVs of Blenheim IVs were cleared to use 100 Octane fuel and the practice was to fill the outer fuel tanks with this grade, using it for take-off with extra boost; the inner wing tanks were filled using 87 octane.
(Graham Warner, The Bristol Blenheim: A Complete History, 2005, pages 96-97, 99-100.)
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03-27-2012, 11:40 PM
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