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I've uploaded a graph comparing the performance in terms of acceleration of various types of traction that forum readers might be interested in?

The graph shows the acceleration of trains at 1/4 mile increments up to their respective top speeds. Data included is for HST's of both 7 and 8 carriages, Turbos, and 180's with 4 engines out of 5 working. Data is based on actual downloads and uses the best recorded based on several downloads of each train type.

The data is from a standing start heading west out of Slough station (which is practically level track), with moderately loaded trains, where no wheelslip was encountered and the train was driven to the relevant driving standards - i.e. a progressive increase in power notches, and on HST's full power not being selected until the whole of the train had left the platform.

It's interesting to note that although a Turbo has the initial advantage, they soon drop off and are left trailing by the 125mph traction. It is also interesting to note the differences between 2+7 and 2+8 HST's. Unfortunately I have yet to get my hands on enough data for a fully working Adelante as it is quite unusual to get all five engines working properly and there to be no wheel-slip this time of year. When I can get hold of data I will add it, but for the meantime it is interesting to see that an Adelante with one engine out still matches the performance of a full-length HST.

To view the graph click on the link below...

[img=http://img164.imagevenue.com/loc994/th_85566_img222_123_994lo.jpg]http:// (http://img164.imagevenue.com/img.php?image=85566_img222_123_994lo.jpg)[/img]

Thanks for posting this!  Interesting to see such a comparison!

One question the data for the Turbos - I assume this is for a 2 or 3 unit set rather than a 5 or 6 one?

Cheers,

Boppy.

My pleasure. It was a 3-car 165. As all 165/6 turbos have engines rated the same then it doesn't make much difference what length they are. The only difference is that in theory 166's are slightly slower as a small amount of power is drawn to supply the Air-con equipment, but in practice this makes very little difference.

When travelling on them, I've always reckoned that you can feel the better performance of a 3-car 165 over a 166 (air conditioning) or 2-car 165 (more resistance per engine).  It would be interesting to compare performance on Oxford fasts (which the weekday evening trains from Paddington after HSTs stop permit 2051 3-165, 2121 3-165, 2148 2-165, 2222 3-166, 2248 2-165, 2322 3-165, 0021 3-166).

Jonathan

Trust me, Jonathan - the difference is so minute as to not be worth mentioning. The general variation of each engines efficiency would make more of a difference, i.e. three good engines on a 166 would outperform two average engines on a 165/2.

The only noticeable difference was when Thames used to hire 'Chiltern' turbos (165001-005) which had better acceleration due to being geared for a 75mph top speed. Those sets have long since gone back to Chiltern though.

I've added the data from a Class 180 'Adelante' which had all five engines working well. Having mislaid the original file, I'm afraid it's a bit of a Blue Peter job with a pencil, but it shows what a 180 is capable of. Does this train have the best acceleration of all the diesel units in the UK? I'm guessing a Voyager/Meridian would be very similar, but I think the winner would be a Class 185 Desiro - a friend who has driven both says that a 185 in full working order literally leaves everything on the starting blocks...

http://img249.imagevenue.com/img.php?image=00854_img344_122_362lo.jpg (http://img249.imagevenue.com/img.php?image=00854_img344_122_362lo.jpg)

And the fuel tank empty!