Interesting point Hobo and probably right on, but our good old British Lancasters got their tails up a bit quicker than that.
When I cut my teeth as an Instrument Technician Smiths had recently introduced an ASI designed for 'heavy jets' - the Mark VI as I recall - on which the lowest reading was 60 knots and and the pointer didn't move at all until that speed was reached. In this case 80 knots, being at the three o'clock position, was a good speed to confirm that it was working. We did have a Vulcan get airborne with the Pitot-Statics inoperative and he got down safely but it isn't something you'd want to do on purpose.
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Through difficulties to the cinema