71000

Commendable honesty there and good to be realistic.
Once it starts hauling those Mk3s up and down everyone can start to be a bit more optimistic.
One thing's for certain, they will be getting all the support they need from the SVR to get the loco commissioned.

 

I've seen clips on Facebook of it running yesterday and it sounds proper 6 beats per revolution with a decent 'bark' to it

 

First loaded test run has took place this morning.

 

Looking rather nice coming through Arley and sounding superb accelerating away, so don't end the video too soon !

 

Caught the Duke today on its second loaded test run of the day, congrats to everyone involved, looking forward to hearing the chatter on the mainline soon

enjoy
Matt

 

I'd call it more of a chuff than a bar.k, as to be expected from a Kylchap.

 

Vezi atașament 91776 First loaded test this morning Vezi atașament 91776

 

That poor lamp

 

Remarkable to me ...rather sharper than a Gresley... does the type of valve gear play a part here ?... I've never looked into this

 

Poppet valves tend to open and close much faster than piston or slide valves, effectively giving larger port openings at the beginning and and of the valve events and so increasing steam flow. A sharper exhaust is one result.

 

I assumed that...but's it nice to have it confirmed...many thanks..

 

Interesting discussion. There are certainly plenty of things about Caprotti gear which I do not understand but among rotary cam poppet valves, Caprotti seems to be unique [?] in that the valves always open fully with the cut-off determined by the length of time for which the cams hold the valve open. Caprotti-fitted locos can certainly run at very short cut-offs, down to 5%. As to steam flow, in theory one can size the valves more optimally but on test 71000 did not pass any more steam (lbs/hour) than a V2 (but produced a greater ihp), the advantage perhaps due to being able to pass more steam at shorter cut-offs. The indicator cards for 71000 on test show a very vertical inlet line (in the nature of indicator diagrams they do not give any comparable feature for the exhaust opening). In fact the description of the valve gear in the test report states that the cam profiles are designed for "low opening and closing velocities with smooth acceleration to avoid roller bounce", but in isolation that does not give any comparison with say Walschaerts. A feature of Walschaerts is that the maximum velocity of the valve is when the piston is at front or back dead centre i.e. the valve opens to steam quickly (the valve gear is 90 degrees out of phase with the piston so at that point the eccentric rod /return crank connection is at the top or bottom of its circle and its horizontal velocity is greatest and consequently so is the velocity of the fore/aft motion of the expansion link/valve). This does not of course apply to the exhaust opening, which suggests that the chuff of Caprotti is due to the characteristics of the exhaust valve opening (as one might expect). This is perhaps offset sound volume-wise as Caprotti allows a shorter cut-off and later release so the steam has probably expanded to a lower pressure.

 

My understanding is that the owners experimented with different cam profiles and those fitted differ from those when the engine was in BR service, so the results of BR testing aren't now valid. The profiles determine the opening and closing ramps given to the valves and vary from very gentle to very abrupt, both admission and exhaust, and therefore the rate at which the valves open and close. I have no idea in which direction the current profiles lean.

 

Is this the best loco built for a British railway hauling the best carriages built for a British railway?

 

No thats 35028!

 

..........

 

Continuing loaded trials today (in between service trains) by looks of it.

 

LE mileage again due to air brake/generator/compressor issue.

 

I presume those tests were in BR ownership when the draughting was all wrong because of the too small holes in the ashpan and not having Kylchap. With the draughting sorted out during the restoration, I would expect the Duke's boiler to produce a lot more steam than a V2's.

 

Harry, are we expecting more loaded runs next week ?