Mallard: streamlined for speed

Devils Advocate...

This is possibly the wrong place to put this, and it would be academic as Mallard is credited with the record for steam, but has anyone ever done any studies on which of the two rival streamlined designs for the pacifics (Gresleys and Staniers) and worked out which was actually the most aerodynamic and efficient? I wonder how much of the record was actually down to a suitable route and trackwork for the run and how much is actually down to the streamlining? I would guess it would be possible to simulate the conditions with a computer and models?

Of course there's nothing like a real life test to be accurate (hmmm Duchess of Hamilton and Mallard restored to steam and comparitive runs on both the East Coast and West Coast Mailines...of course they both have to be attempts at the records....).... now there's a thought...

 

I keep trying to reply to this thread, but for some reason it keeps telling me that I need to get my comments approved by an administrator, yet when I quote I can post!!...

What I wondered is has anyone done any modern studies to find out if Gresley's A4 Streamlining was really any more effective than Stanier's on the Coronation? Or was it other factors such as trackwork and gradients that lead to the LNER taking the speed records.

I guess no-one can really know without comparative studies over both the West and the East Coast Mainline.... hmmm restoring Duchess of Hamilton and Mallard to steam for comparative trials anyone?.....

 

The steam entering the cylinders provides a cushioning effect if you like. The piston reaches the end of its stroke and there is steam there wanting to push it back in the opposite direction. When steam was shut it then the cushioning effect had gone and suddenly the big end bearing had to take the force of the piston, which weighs a fair weight, trying to keep on moving in the direction it is travelling. With no steam there to stop it and act against it (the cushioning effect) the big end bearing got extremely hot under the stress and started to melt.
Slowing down by shutting of the throttle partially would of still allowed some steam to reach the cylinder and work against the piston. That isn't to say it still wouldn't of started to melt but then it may of given the bearing chance to remain intact as speed fell. In the end Mallard wasn't out of action for very long.