Flying Scotsman

I note in this photo and the one at Appleby, RTC are making a point to NRM/DB that they ran the first public tour with Flying Scotsman. And why not?

More from the Scot's first run later.

Peter on a bright morning in Manchester - those two runs should have been today!
http://pjhtransportpix.zenfolio.com/f731739511

 

Sorry, but I'm going to take issue with you on this. The LNER preferred a solid forged piston head & rod. The piston head has to be a certain width to enable thef itting of rings. As it is solid if the head as made plain (undished) it would be a significantly greater mass than is desirable so it is designed the way it is. To minimise clearance volume, the cylinder cover has to echo this shape, leading to the arrangement shown. The GWR and LMS post Stanier opted for cast hollow heads which could be plain and flat.
Clearance volume is another variable that will contribute to things in considering the strength of a 'beat' . Ideally, the clearance volume wants to be zero but you can't have this in a practical engine, which has to provide clearance when both cold and hot and clearances at both ends of a cylinder are rarely equal. As to whether the valves are set correctly, the essence of this is not in the loudness of the exhaust but in the timing of it. The 'event's of Walschaerts valve gear are inexorably linked; you cannot vary the point of exhaust relative to the point of admission and cut-off without re-designing the gear. If the exhaust beats are evenly spaced, the valves are correctly set. They will not be equal in sound for the many reasons already mentioned on here.

 

I agree that there are several possible reasons for either the loudness or the timing to be irregular. However any differences between cylinders in when the respective inlet ports close will certainly cause differences in the amounts of steam in the cylinders and therefore in the loundess of the sounds when the respective exhaust ports open, and I think those differences will be more noticeable than differences in timing of the exhaust beats. As for the piston rods, I remain unconvinced that they make any significant difference, but insofar as they do many any difference that should be about the same on all cylinders, giving three louder and three quieter beats.

I come back to my earlier observation that FS is sounding more even than most locos that I have heard.

 

Thank you kindly, good to know!

 

The beats are certainly evenly spaced according to the frequency analysis shown above, which does show the exhaust timing is correct. Of course we can't hear the inlet timing to know if the effective cutoff of the inlets are all exactly the same. I suppose if one end of one cylinder had less cutoff, for whatever reason, it might be working harder and thus have a louder exhaust.


On the other hand

No argument there..

In which case the slightly louder beat could be a result of the shape of the exhaust passages and the order in which the cylinders exhaust into the manifold beneath the blast pipes.

As long as it runs as well as it did yesterday, I guess it really doesn't matter. Interesting , though.

 

On reflection you are probably right had a bad day yesterday and that seemed a good alternative to kicking the cat!

 

I looked on real time and could find no path activated to york last night i know the original path to return 60103 to carnforth was cancled, so will she be on display at york whilst the repaint is caried out? or will she go straight into an private area of the musseum? one for Mr C i guess?

 

You may be missing my point, since both cylinder covers are different and given the shape of the piston, I cannot really imagine that Gresley did not design both cylinder halves to be of equal volume. So the volume of the piston rod would be taken care of.
Kind regards
Jos Koopmans

 

The NRM has a dedicated paint shop, which, other than a few door windows, is out of public view.

 

I think you may be missing @Steve 's point. Yes, the percentage clearance volumes can be made (approximately) the same, but the effective cross sectional area of the back face of the piston is reduced by the area of the rod relative to the front face, and no amount of adjusting the shape of the piston face will compensate for that. The swept volume ahead of the piston is piston area x stroke. The swept volume behind is (piston area - rod area) x stroke. Tail rods resolve this.

 

Footage of Flying Scotsman at Shap summit , Howe & Co and a wet Birkett .

 

I would like to suggest to you to study the A3 cylinder drawing first. The front volume is diminished as the front cover enters the piston, so the front volume is compensated imho.
Kind regards
Jos Koopmans

 

I fear we are talking at cross purposes. Consider a piston in a vertical tube. Fill the tube to the brim with water above the piston, and push the piston upwards a set distance (the piston stroke). Measure the amount of water that spills out over the edge of the tube, that's your swept volume for the front of the cylinder. Now connect a rod to the top of the plunger (the piston rod), extending beyond the top of the tube. Repeat the experiment, and you will get less water spilling out for the same vertical movement, your swept volume for the rear of the cylinder.

No amount of changing the piston's profile across the cylinder will change these results, unless you change the shape so much that the top of the piston is clear of the end of the tube at the end of the stroke. In a real steam engine cylinder this will be very noisy and destructive. The amount of vertical distance left above the piston when it finishes its stroke (the clearance volume) will not have any effect on the amount of fluid displaced either.

 

there was a path activated, arrived into York 20 early, round midnight. It is having brake tests today and tomorrow so will likely be outside while they are carried out

 

Excellent video Stephen, thanks for sharing.

 

Just wondered if there was any more info on when FS goes back to York - agreed nothing on UKSteam Movements
Cheers

 

It's already there. Went straight to York after the WCME.

 

I don't have an A3 drawing and I don't know what the answer is, but the attached drawing of an SAR class 25 gives some idea of the lack of fore and aft symmetry of (some) cylinders. I guess it also depends on whether front and back clearances are the same.

 

That's certainly quieter than lunchtime...

I am no great fan of FS but the manner in which she seems to have inspired people is truly remarkable the crowds at Carnforth were amazing and seem to have been repeated at least at oxenholme and Carlisle.

Also much kudos must be given to the NRM PR department who are getting great national mainstream coverage.

I mentioned before but does anyone with some time on your hands (there seems to be a few of you ) care to calculate what mileage she put in yesterday - must be an impressive figure!

 

Another thing I forgot to say/mention, is that if you have the chance to have a closer look. You'll notice that the third drain comes out at about the mid point on the outside cylinders through a small [hidden] hole in the frames. And are not connected to the outside cylinders at all.