Jimc's Recent Activity
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Jimc replied to the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
But a pen overshoot will happen every time. Assuming its driven by something like a solenoid. The pen will accelerate up or down but when it reaches the point where the solenoid is trying to put it its inertia will put the flick in. That's just...
May 28, 2023 at 10:56 PM -
Jimc liked Jamessquared's post in the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
There's a difference between "designed in" and "something which the LNER’s own assistants clearly used to measure against." If the little spike is caused by the inertia of the pen - as @Steve suggests - it would occur pretty consistently; after...
May 28, 2023 at 10:16 PM -
Jimc liked Steve's post in the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
I'm a bit busy at the moment and haven't had time to read Dave Andrews paper and have only skimmed what has been said on here so it might already have been said. However. looking at the trace and the so called 'tick' shown in Jimc's post, that...
May 28, 2023 at 8:58 PM -
Jimc liked S.A.C. Martin's post in the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
Okay, I think we need to be clear on the terminology and what's being said. My apologies for not being clearer. When I say "quarter mile" in relation to the graph paper, that is a physical measurement of the actual distance covered, and is not...
May 28, 2023 at 11:59 AM -
Jimc attached a file to the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
I'm not sure you're understanding of what he's saying is the same as mine. We don't have a sine wave trace on the paper. The one second "tick" trace approximates to a square wave. Its not actually a square wave because its a mechanical device, so...
May 28, 2023 at 10:08 AM
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Jimc replied to the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
As I understand it, David Andrews has demonstrated that the recording paper was not moving at a constant speed, but was slowing down and speeding up slightly at one mile intervals. His chart demonstrates this, and suggests that the first two...
May 27, 2023 at 7:24 PM -
Jimc replied to the thread Sir Nigel Gresley - The L.N.E.R.’s First C.M.E..
That's IMHO a very good piece of analysis by David Andrews. I particularly like the way he's picked up the cyclical error in the paper speed underlying all the other factors. I wonder if one could look at the mechanism - if it survives in the...
May 27, 2023 at 5:19 PM
