pethadine82
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Say on a flat gradient, a typical HST 9 cars travelling at 125 MPH, how many miles can it travel just coasting before it gets to zero MPH? Assume the passengers are all seated.
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HST coasting distance from 125mph
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Mordac
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Is this your physics homework?
XCTurbostar
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Difficult to say since there are a lot of variables.
You start with a lot of kinetic energy but your final state is no kinetic energy so you would need to work out the rolling resistance (coefficient of friction) of the consist and aerodynamic drag and minus both of these as a function for time.
There are some answers online but if your expecting a perfect answer, it would take a lot of work!
pethadine82
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no not at all, I just remember the times on the ECML I used to take the HST and it had a good bash but even at Hadley wood to Ally Pally it was still doing a decent speed. I just thought of it today, and wondered when BR made them if they had any tests or if anyone could give an educated guess.
hexagon789
Veteran Member
Didn't (or doesn't) the GWML have coasting markers at a point where shutting off power at 125mph would allow a train to coast down to 100mph prior to braking for a station stop?
The distance they are set might give an indication of at least how far it takes to coast from 125 down to 100.
Having also read many Practice and Performance articles in the Railway Magazine, ISTR one where a run in an HST on the souhern ECML, the driver shut off power at 125 for a 120 restriction - power shut off about 1 mile before for the train to coast down to 120.
So if it takes 1 mile to lose 5 mph at 125mph, as speed falls it will take further and further to lose each 5mph increment of speed.
The distance they are set might give an indication of at least how far it takes to coast from 125 down to 100.
Having also read many Practice and Performance articles in the Railway Magazine, ISTR one where a run in an HST on the souhern ECML, the driver shut off power at 125 for a 120 restriction - power shut off about 1 mile before for the train to coast down to 120.
So if it takes 1 mile to lose 5 mph at 125mph, as speed falls it will take further and further to lose each 5mph increment of speed.
A BBC documentary back in the early 1980’s with (iirc the BBC presenter (Age of the train) who should now not be named) in the cab once asked a driver what does it cost if you just momentarily touched the brakes, and the answer was it literally burns a £5 note… dunno what that is in todays money.
hexagon789
Veteran Member
About £25-30
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