P2 Locomotive Company and related matters

That does seem to be about the only point of similarity though.
The challenge of wanting to direct the air flow away from the body (incidentally increasing drag) instead of keeping it as close to the body as possible does seem to be a unique one to the steam engine, which is probably why its created so much trouble. Thinking about it the rigid loading gauge and the need for length in the exhaust system is another issue that would seem to be peculiar to this design challenge. You can't simply put an aerofoil above the chimney to send the airflow where you want it. [sudden vision of a pantograph like structure height controlled by the overhead wires incorporating an aerofoil to lift the exhaust!]

 

I don't see that the aerodynamics of a plane doing 200 knots has any bearing on a loco chugging along at 50 MPH..

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And yet billions has been spent on the aerodynamics of motor vehicles which spend most of their lives averaging a very similar mph
When you see the shape of the cowl,on a round bodied object, and how it might be partially introduced onto a P2... Interesting

 

Looking through the earlier posts I found a discussion on the As/Ar ratio of the boiler tubes.
I would like to point out that to regard this ratio for tubes only is very misleading, the As/Ar ratio
of the flues is more important and should be better than that of the tubes to prevent preferential
draughting through the tubes.
Kind regards
Jos Koopmans

 

Looking for some information on the P2 I found Nock’s description in his “British Steam Railway Locomotive 1925-1965“ page 103. He gives a description of the “principle of the double blastpipe” which I regard as pure fairy tale. He regards the surface area of the jets as important and mentions the increased total circumference of both the orifices as argument. However he forgets the diminished height of the jets which lead to exactly the same total surface area in contact with the smokebox gases. A prime example of an engineer not wanting to do the math! Surface area has been mentioned to me before. Please note that since before WWII the entrainment ratio of a jet has been given as a linear function of the distance from the orifice. However, the surface area of a cone increases distinctly non-linear with the distance from its apex (below the orifice) so it would take a mathematical genius to prove that a non-linear surface increase gives a linear entrainment ratio as result!

Nock also has the front end drawing of the Cock o’ the North, fig. 152. Since the P2 website tells that the chimney has been cast, I can give my opinions on the double Kylchap.
Probably I am the only man alive that has measured the effect of the Goodfellow projections in the orifice, the results were give in the 2006 symposium in York: no good, increased backpressure and no effect on the vacuum. Imho the only good item in the Kylchap is the Kylala spreader, making the system four orifice units. All entrances of intermediate petticoats are poor, cones instead of radii. This is also valid for the chimney, extremely poor blunt entrance. A disadvantage of the Kylchap is its poor alignment, probably this is solved in Tornado. Also there is far too much material present, apparently nobody appears to understand that both chimneys can be combined into a common oblong one with less friction losses which are very detrimental for our desire to eject the steam/gas mixture to above the air flow around the smokebox and boiler.

Finally I would like to point at results of a huge number of tests by the American Prof. Goss with what he calls “draft pipes”. His conclusion “Double draft pipes make a small stack workable. They cannot serve to give a draft equal to that which may be obtained without them, provided the plain stack is suitably proportioned”. Ref: “Locomotive Performance (1907)” page 261.

As far as I am aware nobody has ever published a calculation of a Kylchap. However, it is quite possible, one needs “The Fire…” and the formulae therein for a serial chimney system calculation.

Please forgive me, ramblings of an old man!
Jos Koopmans

 

Always delighted to read your informative - and educational - ramblings Jos, please keep them coming.

Cheers,

Alan

 

But is the Chimney that has been cast identical to 2001 's ? One suspects it may be a little shorter and wide enough to suit the proposed blast pipe and cowls
One also suspects that, apart from revisiting the Staying and Foundation ring for the firebox , the boiler design will be almost identical to Tornado.
All things being equal then the trust will no doubt attempt to somehow replicate the Chimney / Blast pipe arrangement of Tornado into the P2 Smokebox.
( which is a different shape and possibly a different volume) and pay little attention to the originals.
From this perspective the only concern that something different may be required would be from the slightly Larger cylinders and the different profile of exhaust release from the proposed 'evolved' lentz valve gear.
Modifying the exhaust release profile to suit the draughting or ideally the other way round is in the hands of its builders...

 

The P2 is a 3-cylinder locomotive which should carry a smaller exhaust than a 2 or 4 cylinder version. What would be the difference in release between an instantly lifting poppet valve and the simultaneous release of 2 cylinder halves in a 4 cylinder with standard valves? The consequence would be a tiny increase in orifice area.
Kind regards
Jos Koopmans

 

Thanks JK, All the P2's including the New one have 3 -Cylinders in common with 60163 Tornado.

 

Yes - but Tornado is three sets of Walschaerts gear whereas 2001 (and now 2007) were three cylinders with Lentz gear. The other P2s were all conjugated 2 to 1 valve gear locomotives with 3 cylinders. So potentially - despite the commonality of parts with Tornado - there's still more to look into and change.

 

No more than already described in my earlier post.

 

Ummm.... actually the proposed cylinders on No. 2007 will be smaller than the original ones, this is to compensate for the higher boiler pressure and to ensure No. 2007 fits the NR loading gauge!

Foxy

 

But (READ THE POST) they are larger than the comparative locomotive (Tornado)

 

I've been looking at the facebook updates and smiling a lot this week. Seeing the new P2 come together gives me a great deal of satisfaction as a Tornado supporter and P2 founder member. I wish of course I could do more, but that's by the by. Anyone who has seen the latest pictures will know that the cab roof, smokebox door, running plate and lots of other details are all coming together very quickly. I've noted the Spencer buffers have been fitted too (one less detail to get wrong on my 4mm model!)

I just hope that no.2007 is born into a world where steam traction is still allowed on the mainline: the news from other quarters this week have caused not least some incredulous responses from a number of people across the world. I am glad that there are teams like the A1 Trust who can show how it can be done, and done well.

 

What's the defining feature a loco has to be restricted to 75mph? Is it regulated by the reciprocating motion and the minor imbalance in the application of power (hammerblow?), driving wheel size or another factor?. Being new and not heritage loco's, why are 60163 and the soon to be 2007, restricted to 75mph? I've never fully understood this.

I've been keeping up with 2007 too, being a covenantor, and it now looks distinctly like a loco coming together. When the frames etc are flat on the ground and parts are still extant, its nice to see progress proceed as it has. We may have a P2 completed before we know it.

 

Agree entirely, I was very doubtful when the Tornado project was announced but immediately became a founder of 2007 saying that this was the one they should have built in the first place. I got an email back from Mark Allatt saying he only ever saw Tornado as the trial run.

The original project has, I think, motivated others to launch new build projects, some of which will come to fruition and some won't. The interesting thing is that one of my former work collegues became a Tornado covenantor having expressed no interest in railways before. He just thought it was a worthwhile project to further British engineering skills.

 

It's wheel size AFAIK. 6ft and under = 60mph. Over 6ft = 75mph, so Black 5's ae 60 mph but a B1 is 75mph. There's also a lower limit for below 5ft eg 8F, Panniers etc. See here for more http://www.uksteam.info/tours/locos.htm

 

I was too young to understand, but when Tornado was announced my late grandfather was thrilled and buzzing. He always believed it would succeed though I don't know how he'd have felt about the German built boiler! I'm more receptive to such things and think the trust made the right decision for the time and have done consequently.

I feel that another Pacific after Prince of Wales would be best for the trust, but suspect I wouldn't get any backing for a Thompson A2/3...!

All said, having two high power and fast class 8 passenger locomotives in one's stud will prove to be an advantage in years to come, that I am in no doubt.

 

How about re-creating the W1?

 

Super - A4 if this US scheme beats Mallard' record!