Big Err wrote:I think the braking performance used is akin to a Ford Anglia with cross-ply budget tyres and all round drum brakes without power servo assistance.
Car braking performance is much better now, just a pity that driver reaction isn't (in many cases).
Mr Cholmondeley-Warner wrote:It was taught to me as "halve the first digit, multiply it by the speed, and add the speed"
so 30mph gives 3/2 (1.5) * 30 (45) + 30 (75)
avoids any mental "squaring".
A little tinkering with Excel suggests the original figures were derived using a deceleration of 25 fps^2 (about 0.77g) and rounded up to the nearest foot. You get:
30 = 44.86 ft
40 = 79.75 ft
50 = 124.61 ft
60 = 179.44 ft
... and so on
crr003 wrote:You'll have noticed in the latest edition of HC that the Imperial value for stopping distance at 60 m.p.h. has been reduced from the "old" value of 120' to a new value of 118'.
Something to do with converting the metric distance back to Imperial.
Mr Cholmondeley-Warner wrote:crr003 wrote:You'll have noticed in the latest edition of HC that the Imperial value for stopping distance at 60 m.p.h. has been reduced from the "old" value of 120' to a new value of 118'.
Something to do with converting the metric distance back to Imperial.
er ... 40 mph?
jbsportstech wrote:I dare to say that in the 60's with a drum braked anglia alot fo people drove safer with better planning and observation as if the didnt they had little or no safety features and the brakes where not amazing.
MikeB wrote:Thanks for your contributions and interesting comments even though we did not get to the 'end of the road' so far as the original question is concerned.
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