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Discussion in 'Traction & Rolling Stock' started by Clansman, 12 Nov 2016.
However most of the feedback on here has been positive, so why would Scotrail care?
I'm holding out a feeble hope that this might mean we are left with a couple of openable droplights on each train...
I've looked through this thread and I can't see any mention of the power cars' use. Is it intended that both will be under power in normal operating conditions? If so, this will give, for example, 4500hp for a four car unit! If only the leading power car is used that still gives 2250hp - surely ample for a four or five (or even six car) unit?
If you look further back in this thread there's a clue where it mentions the HST's being used to cut journey times.
I imagine that they won't be especially exercised by it - it's hardly commercial dynamite. I don't think there is anything in the information that is either particularly surprising or that hasn't been widely speculated about already.
They are still deciding but "Bothy" talk was that we will be driving them with rear power car in use only but that is not confirmed..
They will make a decision once we get a set up to play with for timing runs etc
Indeed - but having 2250hp from a single power car for four or five cars would presumably easily achieve this, so I am no nearer an answer.
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Thanks. Would having only the rear power car working pose any problems for the driver in terms of monitoring engine performance, sounds, etc., or would the benefit of a quieter cab for the driver outweigh this? I imagine the option of firing up both cars would give considerable scope for recouping lost time!
You can monitor both power cars and it will definitely be quieter for sure.
Personally I would prefer using both power cars (on the 2+5s) and getting up to line speed then coasting quicker but I am sure they will do a lot of running with different set ups etc
A 4 + 2 would still have 500 odd BHP per car on one PC so nippy enough but for 5s I would have both
Would be le less than 500 because you have the dead PC in front being pushed, forgot about that
I would have thought the answer would be fairly obvious a full size HST isn't regarded as being particularly fast accelerating these days, so 1 power car pulling 4 car carriages offers about the same as an existing 8 car HST, well in fact it doesn't because if you add a non powering HST car then the single car HST is dragging about 6 coaches around, so the answer is you are going to need both power cars for a decent accelerating train.
It'll be interesting to see which option is adopted. Nearly 500hp per car is still quite hefty, and Scotrail may wish to reduce maintenance costs by using only one PC at a time in normal service.
I doubt there is any option to be chosen the new HST services will require both Power Cars running to meet the timings, particularly on the Inverness services.
Thats not what our management are saying mate, as stated they are considering using the rear PC only.
I disagree with it but I am sure when they do timing runs it will become clearer and hopefully they agree with you and I
Frankly I'm surprised at that comment since they are supposed to be speeding up the services, I can possibly see that maybe on some sections of some of the routes 1 power car HST might be ok and you a adopt a sort of eco strategy like the 185, where they switch 1 engine off some of the time, although there is a slight difference between losing a 1/3 or your power and verses losing 1/2 your power, plus isn't the issue with HST MTU engines about them getting too cold if switched off for too long and needing a shore side pre heater or can the other engine supply the pre heater?
To answer your last point first, the pre-heater works off the ETS so the other power car can supply to the pre-heater on the dead one.
As for the point about using one power car only, I agree with you. Everyone else seems to have forgotten 70+ tonnes of dead weight in the formation! A simple calculation shows a 2+4 set on one power car has a lower power:weight ratio than a Class 158. The answer is blindingly obvious.
Typical scotrail, all cost and nout else. The point I thought of the HST was being able to take the HML at a bit more than cycling pace and so 2 PCs needed. They will be nippy on that but thats whats needed
Particularly as the whole point of using the HSTs was to achieve Voyager timings without paying Voyager leasing costs. So if you don't run faster than 170s you don't get the extra franchise payments.
Yeah, but there's a lot of Edinburgh-Aberdeen and Glasgow-Perth that's relatively flat where a single PC wouldn't struggle to keep time. I suspect it'll be horses for courses.
Nonsense. As I posted above a 2+4 set has lower power:weight ratio than a 158, so it will lose time against existing timings. That is before taking into account that HST power cars are geared for 125mph so will be slower accelerating than a 158 or 170.
If it does end up with both PCs working a four trailer set, that will be quite a power-to-weight ratio (>16:1). However, noting the gearing point, acceleration may still not be that spectacular, just constant!
The HSTs will be running limited-stop services so the acceleration is less of an issue. Plus, have you been on a 170 recently? Treacle accelerates faster on a winter day.
Edit: As an aside, I was on a VTEC HST with a failed power car that only lost 20 minutes between Dundee and Kings Cross.
I'd also like to nominate the 168s for that. The only time I'd rather be on a Voyager heading through the Chilterns.
Come to think of it, I wonder if any of the ScotRail modifications will feed back to the GWR short sets - If that does take place (which seems likely with the way things are going).
I thought the GWR short sets had been replaced by an additional order for IEP?
I think it only partially fixes the problem, allegedly the short sets are still going ahead although of course there still has been no official announcement on this as yet. According to what Ive read else where its still 11 sets plus a spare 4 standard only including a TGS.
As far as I know even a 2+9 HST rake can beat a 170 to 100 mph. A 2+9 HST takes about 3 mins 45 secs to make a ton, whereas a 170 will take about 4 mins 15 secs. A 2+7 HST set should be able to reach 100 mph from a standing start in about 3 mins 15 secs and 125 in a further 4 mins or 7 mins 15 secs overall.
OK, here are the power:weight ratios (using engine hp at the crankshaft) to give the comparison:
HST 1+5(+1 dead): 7.1hp/t
HST 1+4(+1 dead): 8.0hp/t
HST 2+9: 9.8hp/t
HST 2+5: 14.3hp/t
HST 2+4: 16.1hp/t
ScotRail are looking to accelerate services - it was mentioned earlier about Voyager-type timings. Towing a power car around dead gives inferior performance to 158s, 170s etc etc. If ScotRail want to accelerate timings they HAVE to use both power cars. If they use only one power car they will have to decelerate services.
Really? Despite the fact that 168s are no more than a minute slower (many timings comparable) over the section of route that they share with Voyagers (Banbury - Leamington), and for that matter offer comparable journey times between Banbury and Birmingham in superior comfort (always a contentious yardstick to use, but I certainly think so)?
Granted that their hill climbing ability may be limited (though the unit I travelled on over the Highland main line had no evident qualms with ascending the banks), but personally I think that the acceleration so-called 'issues' associated with Turbostars are somewhat overstated for many of the routes that they operate. That's not to say that there isn't an opportunity here to accelerate Scottish inter-city services through the use of short formation HSTs, though.
As is typical, after saying that they are very rare, what did I see today? Doubled 170s working an Edinburgh to Aberdeen service.
Key bits of it aren't though. The starting blocks at Glasgow Queen Street being the very first one of them.
If the timetable isn't recast prior to the introduction of HSTs, you've then also got 10 calls at Dunblane (5x Inverness & 5x Aberdeen), of which 4 of the Invernesses also have the slog out of BofA - where the 170s barely feel like they hit 30mph before the Kippenross coast.
I was thinking about the climb out of Queen Street and a few of the other gradients. Seeing as it's been confirmed that the engine heaters are supplied by the ETS I wonder if it is possible to start/shutdown one of the PCs en-route?
Quite a few of them are regularly doublers on the Highland Main Line on a Sunday, and I had one the other week where the rear unit was locked out of use. Very very rare through the week.
The engineering work on the Stirling line this weekend might be disrupting things a bit as well.