samuelmorris
Established Member
It's less than a 3-car 755, put it that way. A unit that it not only half the size, but also only (currently) set to run at 100mph.The 2000kW total motor rating seems too low somehow.
It's less than a 3-car 755, put it that way. A unit that it not only half the size, but also only (currently) set to run at 100mph.The 2000kW total motor rating seems too low somehow.
It's the only figure that looks suspect. The vehicle lengths look fine, engine ratings, seating capacity and weights.It's less than a 3-car 755, put it that way. A unit that it not only half the size, but also only (currently) set to run at 100mph.
I got it from a PDF I downloaded a while ago, but I see that's the same source wiki quotes so perhaps not the best. Don't the 802s plus GWR 800s also have larger fuel tanks? Which would add weight.
It's less than a 3-car 755, put it that way. A unit that it not only half the size, but also only (currently) set to run at 100mph.
You can never have enough powerThe 755s are notoriously overpowered!
Indeed, each new design of late has made travelling with a Mountain Bike less and less easier, be it the stupid design in the Voyagers (and carried over to the Scottish HST's of hanging them from the ceiling) to the annoyingly narrow bike racks on the floor of the 444 - It seems each new design is based around super thin road bike's, which of course have thinner tires and a thinner design.The Leicester/Loughborough/Nottingham/Derby triangle commuters who worship mountain bikes will love them then![]()
You mean none of them have larger tanks? I thought the 800s were upgraded to put them on par with the 802s in that respect?Used to, but not any more (as Clarence Yard must have posted a good 801 times by now) - the only mechanical difference between them now is the resistor grids and lack of on the 800s, which will carry a weight penalty of course. That possibly does explain some of the weight difference, but I expect the use of inboard frame bogies on 2 of the trailer vehicles in the 9 car formation will throw the estimate, along with other subtle differences. I don't know if the vehicle weights are quoted dry (I would have assumed so, or at least, not at 100% fuel capacity) so even the larger fuel tanks may not account for as much difference as thought
Even so, it still seems rather low for a 125mph unit.The 755s are notoriously overpowered! They've got a max (not continuous) installed of 2.6MW, and a mean acceleration to 40kph of 1.3m/s2 - almost double the assumed 0.75m/s2 I took from the IEP TTS
It does seem pretty pointless, I agreeInteresting that the "low floor" vehicle isn't either of the ones with wheelchair accommodation. Might it have been cheaper to make them all the same?
You mean none of them have larger tanks? I thought the 800s were upgraded to put them on par with the 802s in that respect?
Even so, it still seems rather low for a 125mph unit.
That's fine, just trying to confirm my original understanding was correct.You're correct - I butchered the response. The GWR 800s have the same fuel tanks as the 802s
Assuming that is the source of the figures, then yes I agree. I do see your point and I would understand that in relation to the diesel output.It all depends on the relation of ratio of continuous rating to the sort of power they can actually get out of them. Instinctively it does seem low but it's not the sort of mistake a company like Hitachi would make
I suppose really the 2000kW suggested is the power to hold at 125mph rather than get there in the first place.
Well, that's for a 5-car set, of course. When they're running doubled up, the wind resistance won't be twice a great. I would expect that 4000kW would be plenty to shift a 10-car consist at 125mph. And power/acceleration matters the most at the busiest periods in the timetable, when trains are most heavily loaded and dwell times that bit longer.when there's any hint of a hill or head wind the'll not be able to hit it
I can see EMR wishing that thelow floor TS was instead made with a high/sloping floor the same as the other four vehicles in the set. That way they could add another engine if it transpires that more power is needed.Interesting that the "low floor" vehicle isn't either of the ones with wheelchair accommodation. Might it have been cheaper to make them all the same?
Doesn’t the centre car have the transformer underneath it? There’s not going to be space for a transformer and an engine.I can see EMR wishing that thelow floor TS was instead made with a high/sloping floor the same as the other four vehicles in the set. That way they could add another engine if it transpires that more power is needed.
I am sure they have done their maths and (perhaps this is a Cinderella line still ?) but it really would make sense to future proof them. More power is bound to be attractive in the future and if GW get more electrification then engines with grandfather rights (emissions wise) should become available. Then again perhaps EMR are hoping that more knitting gets done in the crucial power hungry stretches in the not too distant future, if not the whole route(s). That is certainly my hope/dream.
I can see EMR wishing that thelow floor TS was instead made with a high/sloping floor the same as the other four vehicles in the set. That way they could add another engine if it transpires that more power is needed.
I am sure they have done their maths and (perhaps this is a Cinderella line still ?) but it really would make sense to future proof them. More power is bound to be attractive in the future and if GW get more electrification then engines with grandfather rights (emissions wise) should become available. Then again perhaps EMR are hoping that more knitting gets done in the crucial power hungry stretches in the not too distant future, if not the whole route(s). That is certainly my hope/dream.
Doesn’t the centre car have the transformer underneath it? There’s not going to be space for a transformer and an engine.
Doh. Silly me went all Crayonista over the odd flat floorAs @43096 points out, the TS car has the transformer underneath, so space is already at a premium. Not only that, but given the 2.9MW of diesel already installed, they're not going to need any more engines - it's the electric motors (or lack of) that are the concern! A 5 engined 810 would have a power:weight ratio of 20 bhp/ton, which is about in line with a 755, and entirely unnecessary on an intercity train!
Doesn’t the centre car have the transformer underneath it? There’s not going to be space for a transformer and an engine.
The March issue also has an article on the 810s, which mentions two new facts not mentioned in previous articles. Firstly that the two space saver toilets in the centre TS will be located at either end of the coach instead of opposite each other as on the 80Xs. The second is that the TFT PIS screens won't just be on the bulkhead ends of the passenger compartment but also in the vestibules.
In addition to this article is a side article regarding the seating on the 810s by Ian Walmsley...
Whoops! Yes it was the March issue of Modern Railway!I suppose this is referring to the March issue of Modern Railways, noting you mentioned Ian Walmsley?
From the vehicle weight It looks like:As @43096 points out, the TS car has the transformer underneath, so space is already at a premium. Not only that, but given the 2.9MW of diesel already installed, they're not going to need any more engines - it's the electric motors (or lack of) that are the concern! A 5 engined 810 would have a power:weight ratio of 20 bhp/ton, which is about in line with a 755, and entirely unnecessary on an intercity train!
a) there is more under the TS than just the transformer - potentially 2 sets of traction electrics for the adjacent cars?
I did look at your graphs, but I think I've misunderstood the conclusions you drew. Not your fault, entirely mine - I misinterpreted it as saying they couldn't quite make 125 rather than they would roughly balance at that speed.Indeed, and (coincidentally) the model I used for those graphs earlier when limited to 2MW exactly shows an acceleration of functionally zero (-0.0003m/s2) at 200kph - ie at the balancing point!
That explanation would seem to fit to me, I think it's just that in comparison with the other 80x they have much higher continuous electric outputs than maximum diesel outputsThe isn't that much 125mph running on MML overall but plenty of acceleration/ high power for 6-7minutes max.
With the nominal 2940kW on Diesel, upto 250-300kW will be going to hotel loads etc. so max traction power of 2640kW? which is 33% more than the motor continuous rating which would align with continuous rating total of 200kW (max can be up to 55% greater than continuous.)
I did look at your graphs, but I think I've misunderstood the conclusions you drew. Not your fault, entirely mine - I misinterpreted it as saying they couldn't quite make 125 rather than they would roughly balance at that speed.
That explanation would seem to fit to me, I think it's just that in comparison with the other 80x they have much higher continuous electric outputs than maximum diesel outputs
Right, got it now.The previous graphs don't show that scenario to be fair - they just considered the notional acceleration assuming a maximum power of 1.25x continuous. The 125mph balancing comes from this graph which shows the maximum achievable acceleration for a given power (with total weight as published, and some assumed figures for rolling resistances and drag) with the IEP TTS acceleration profile thrown in for comparison. The 2MW profile hits zero just before 200kph so it'd never quite hit it, but 2MW is the "lower bound" if you like - we know that they've got more power than that available.
It also matches with the engine outputs a lot betterTo actually reach 125mph (away from a lovely theoretical world with no headwind, perfectly straight and level track, no passengers, etc) they'll clearly need more than the notional 2MW continuous (assuming my guesstimated values hold) - but the estimate of 2.6MW from @hwl would seem to be ampl
Because Hitachi won't be responsible for providing a set number of units for service without financial penalty?The possible explanation here is that the other 80x, all being either part of or derived from, IEP with it's financially incentivised reliability will have had more power than strictly necessary thrown at them so that they can still keep to time (or be run even faster, etc) with motors out.
810 being later, and a different design without the same procurement, they can take a more aggressive approach having gained experience on the reliability of their equipment (and not worrying about being stung as hard if motors drop out)
Right, got it now.
Can I just ask how you produce the graphs? What you used.
Because Hitachi won't be responsible for providing a set number of units for service without financial penalty?![]()
800/801 were designed for 140mph on electric hence having far more power than needed at low speeds to meet the TTS acceleration requirements.The possible explanation here is that the other 80x, all being either part of or derived from, IEP with it's financially incentivised reliability will have had more power than strictly necessary thrown at them so that they can still keep to time (or be run even faster, etc) with motors out.
810 being later, and a different design without the same procurement, they can take a more aggressive approach having gained experience on the reliability of their equipment (and not worrying about being stung as hard if motors drop out)
And there was me thinking you had a fancy piece of software kit there!Just google sheets! Not very neat admittedly, but roughly:
For 5kph steps from 1 to 200kph, estimate the resistive force for the speed*, then calculating the force needed to match the IEP TTS profile (F=(ma)+F_res), and then determining the power needed for that (P=Tw or P=Fv - I did the first option because it's the logical one that came to mind when dealing with motors (hence torque) but it cancels itself out). To make the accel/speed graph I have a very rough integration (difference in the speeds/acceleration)
*comprising an independent (static) term, velocity dependant (rolling resistance) term, and velocity squared (drag) term
And there was me thinking you had a fancy piece of software kit there!
Thanks for the explanation
Agreed on the seats. Having now read Ian Walmsley's piece, even he seems cautiously optimistic about the seats in them. Getting confirmation that they are FISA Leans is a good starting point. Certainly going to be interesting to try them out.The March issue of Modern Railways also has an article on the 810s, which mentions two new facts not mentioned in previous articles. Firstly that the two space saver toilets in the centre TS will be located at either end of the coach instead of opposite each other as on the 80Xs. The second is that the TFT PIS screens won't just be on the bulkhead ends of the passenger compartment but also in the vestibules.
In addition to this article is a side article regarding the seating on the 810s by Ian Walmsley. It mentions that seat pitch will be 800mm, which is am amount Ian Walmsley approves of, but to allow this it does mean there are only 6 bays of 4 seats, down from 8 bays which were originally planned and as found on the other 80Xs. As mentioned the seats will be FISA Leans, but apparently will have a more reclined position than their GA counterparts, of 107 degrees to horizontal for the EMR seats vs 102 degrees as found on the GA seats. All sounding positive, but the true comfort test will be sitting on these in reality.