Ton up Tornado

So when is Tornado going to have a go at City of Truro's record?

 

Hasn't it just done so? Round about 100 mph, probably a tad over, on fairly level track whereas CoT's was down the bank from Wellington.

Edit. BTW I suggest all these posts here about Tornado be moved to the Ton up Tornado thread.

 

Very sensible! Remember City of Truro's claimed precise 102.3 mph was based on 8 4/5 sec for quarter mile on a stopwatch that only recorded to nearest 1/5 sec!

Agree re gps - I set my gps to record a track log every second, for analysis later. Very useful for the Bittern 90 mph trips. On the final Newcastle to York run I recorded a consistent 95 max for 7 seconds, but not for full 10 sec i.e. quarter mile.

 

Some interesting points in the thread so far.

I agree that any of the preserved Class 8 locos could do the same as Tornado just has. A fair few of the Class 7 types as well, but it's not so cut and dried and for a couple of them Network Rail might start to take a dim view of the hammer blow. Which leads me neatly onto my next point that, Tornado apart, these are all old ladies and 90mph puts the dynamic forces alone up by 44% compared to 75mph. That sort of increase in force can easily be the difference between fatigue cracks progressing or not - it's not that the parts are in bad condition on the older engines, they've just got less of their life left.

Even Clan Line, a relative baby in the Class 8 club, was withdrawn with about 800k miles on the clock and needed some weld repairs to the frame stretchers during her current overhaul, having done a fair few miles since 1967. So yes, they can all do it, but for those that do there will be an ongoing increase in costs if they repeatedly run at 90 for extended periods. Clearly the A1 group have decided that the opportunities it opens up outweigh those costs. Other groups will make their own choices; there are good arguments either way.

Finally, did anyone else notice the crew commenting that it was "A bit rocky, swinging around a bit," (paraphrased) in the BBC report. Clearly the A1 tendency towards lively riding at speed is something Tornado shares with her forebears.

 

But wasn't the bad riding cured by trying an A4 bogie back in br days?

 

Measuring anything to better than within 5% is very difficult. A lesson I learnt from my Physics teacher about 60 years ago, and its still true. Speed requires measurement of distance and time, so if you get within 5mph at 100 thats pretty good. Frankly 0.6 of an mph is delusiory.

Rob

 

You mean slow down to just under the ton?

 

To do that surely someone needs to pop Tornado in a time machine first.

 

Yes and no. This was as far as I am aware only applied to one Peppercorn A1 - and it was returned to its original format at some point. It is interesting to note that the best riding Pacifics remained the A4s on the LNER and almost all other classes suffer with some level of stories as to their bad riding.

The Peppercorn A1s seem to have suffered particularly badly - but one wonders if this was more about the length of time between classified repairs. Understandably a locomotive doing longer mileage between repairs may become a bad runner of sorts.

 

Considering the immense increase in knowledge about rail vehicle dynamics since the A1s were designed, and the work that the Trust did on that subject before starting to build the P2, there ought to be some scope for improving Tornado's behaviour at speed.

 

I would think any steam locomotive might be a bit bumpy at 100mph+?!

 

Tornado already has the Cartazzi designed for the A4, not the one on the PcA1 drawings ( which is probably the same as the P2, A3..) .and I believe its bogie control settings are on the stiff side for a Pc A1 also
but as acorb says ....

 

Only on the uphill bit.

 

As regards class 50's I recall the 50 Alliance gave instructions for them to be allowed to coast at 90mph, But were given a 75mph under power restriction. This is something Laira depot did to reduce Flashover risk, during the 50 Railtour years 92-94

 

I thought the A3s didn't have too bad a reputation either. Mind you, they came after the Ivatt Atlantics, which according to many gave a truly wild ride. From Townend, I believe the A1s could be quite unnerving straight out of shops, although beefing up the side control springs supposedly helped.

If I was going to dig out my long-neglected vehicle dynamics modelling and extrapolate it to rail vehicles, I'd guess that the LNER bogie and Cartazzi combination was good enough for the A4s, but not quite the master of the A1s, with the middle cylinder out ahead of the bogie pivot and a heavier firebox above the trailing truck, especially if the side control settings were left much the same. If you look at the mass distribution of the two classes, the A4 looks like a slightly better vehicle - less of it out at the extremities, so it doesn't take as much force to guide it and there's less energy to dissipate if it starts a yaw oscillation.

Of course, the Duchesses, with two inside cylinders in much the same place as the A1, had an excellent reputation for their quality of ride (including a well known precipitous entry into Crewe), but then they had a different trailing truck, and the well-regarded De Glehn-by-way-of-GWR bogie.

 

IIRC it was never disclosed at the time exactly what was done to steady up the A1's but something was done. It wasn't the A4 bogie. I seem to remember someone saying from a Works perspective that the ride wasn't considered dangerous, so the modification was made in normal works visits and they didn't want all the A1's sent back for it at once. I don't have time to search for the reference at the moment. If I trust to memory I think it was something like the side forces had not been recalculated since the bogie was designed for the B1's and the cure was to adjust the side control allowing for the heavier loco with greater overhang. There was also the miscalculation of the Cartazzi slides. One gets the impressionm that the difficulties between the Drawing Office and Management (to name no names!) had resulted in some lack of joined up thinking in detail design.

 

I can't put my hands on the exact reference either but it was a much higher loading on the side control springs
for the bogie. Which was discreetly done in the works and not at all mentioned at the time.

 

Maybe because it was being worked at full regulator and 45% cut off?