Hitachi IET Performance on Hills

[Railperf]

Taking the fastest runs by comparison, nothing beats a voyager on all engines, but the low speed sections through Devon don't really allow Voyagers to extend their legs fully. Best comparison would be the 100mph climb to Wellington from Taunton or Tiverton Parkway.
As said before the IET's good low speed acceleration is probably similar if slightly slower than Voyager to 40mph, then the Voyagers are pulling away. The Devon banks limited to 55/60mph - so no real advantage there. What the IET's gain at low speed over an HST is lost on a decent climb. But the more precise and accurate braking again seems to gain IET's time over an HST so that most of the sub 100mph sections the IET's are as quick as HST's formerly were.
From my own analysis, GWR IET's on diesel match former HST schedules easily on sub 100mph track. Increase speed limits to 125mph and IET's are slower than HST. But a Voyager beats both on 125mph track where its power to weight ratio is superior in getting it up to speed easily.

Absolutely. IeT beats Hst hands down in terms of pulling away in slippery conditions. Worlds apart...however braking wise, I've noticed IETs slip a little more than HSTs did, although not enough to warrant concern.

in damp conditions or also dry? Is that because the brakes are much sharper to apply compared to HST where the brakes progressively come on along the train?

 

[Skie]

Shame none of these units will get to run up Leeds Street bank or the Mersey Tunnel. At 1 in 30 and 1 in 27 respectively they’d be interesting experiences.

 

[Ken H]

If the IEP's have less HP/ton than HST, then they will be slower on fast straight track. Blame Newton.

 

[hexagon789]

If the IEP's have less HP/ton than HST, then they will be slower on fast straight track. Blame Newton.

If one makes a few fairly conservative assumptions about the actual traction power you obtain on diesel in a Class 800 (non-derated), you get slightly more favourable power-to-weight figures tgan an average 2+8 HST.

The difference would be more pronounced with LNER's derated 800s but the extra 33.6 tonnes of a further trailer in their HST sets means even then the difference is quite small and in fact by using the same approach I did for the GWR sets, I make it to still be more favourable for an 800 but by a smaller margin.

At least that's what some 'back of the envelope calculations' gave me.

It would be useful to know exactly how much 'hotel power' an 800 car consumes as I had to make assumptions; for HSTs figures exist for full ETS load ratings (ETS index) so I simply assumed a full ETS load being taken when calculating a traction power figure.

 

[RPI]

Shame none of these units will get to run up Leeds Street bank or the Mersey Tunnel. At 1 in 30 and 1 in 27 respectively they’d be interesting experiences.

No but IET'S go between Exeter St Davids and Exeter Central on occasions and don't struggle at all, thats from a standing start at Exeter St Davids too.

 

[irish_rail]

Taking the fastest runs by comparison, nothing beats a voyager on all engines, but the low speed sections through Devon don't really allow Voyagers to extend their legs fully. Best comparison would be the 100mph climb to Wellington from Taunton or Tiverton Parkway.
As said before the IET's good low speed acceleration is probably similar if slightly slower than Voyager to 40mph, then the Voyagers are pulling away. The Devon banks limited to 55/60mph - so no real advantage there. What the IET's gain at low speed over an HST is lost on a decent climb. But the more precise and accurate braking again seems to gain IET's time over an HST so that most of the sub 100mph sections the IET's are as quick as HST's formerly were.
From my own analysis, GWR IET's on diesel match former HST schedules easily on sub 100mph track. Increase speed limits to 125mph and IET's are slower than HST. But a Voyager beats both on 125mph track where its power to weight ratio is superior in getting it up to speed easily.


in damp conditions or also dry? Is that because the brakes are much sharper to apply compared to HST where the brakes progressively come on along the train?

I'm referring really to slippy season. Although I will add, I've not had any really bad slides with IETs in the 3 autumns I've driven them in, compared to a few bad ones with HSTs. Just feels like the IEt is a bit more sensitive to slippyness when braking on a poor railhead, but this may just be anecdotal and I'd be interested in what other drivers think. After all , we are only 3 years into driving them and it is still early days in terms of performance in "slippy season".