Things that seemed a good idea at the time, but in practice are pretty useless.

Had Bulleid asked whom he should have asked, i.e. those who had worked for motor companies who had abandoned sleeve valves or gone bust for not having done so, he would have wasted far less money. According to my own grandfather, if the chauffeur (sleeve valves were normally associated with high end vehicles) did not drive the car on a cold February morning with exteme care whilst the engine warmed through, then expensive mechanical failure could result. A favourite party piece was breaking the drive lugs off the sleeves which is reminiscent of one problem of the Leader.

 

More than likely. As recently as the 1970s you could get mutual unintelligibility in Britain. One of the girls on my college course was from somewhere up country in Devon with a really strong local accent, and we did a field course on Cumbrae in the Clyde Estuary where the locals spoke very dense Lallan Scots. She needed an interpreter in the local shops.

 

To my wifes amusement so did I a few years ago

 

I wonder if the metallurgy of the time was also a massive factor with the sleeve valve engines of last century. Differential thermal expansion of various components would have been one of the main issues, as would have been wear resistance. Modern materials would make such matters less problematic, I would think.

 

Lubricating oil quality at the time would also be a factor. Basically sleeve valves stood a chance in luxury cars and aero engines with the manufacturing qualities associated with both. Even in these uses there were problems. One wonders what planet Bulleid was on if he thought the principle would work in the ash strewn environment of the coal fired steam railway.

 

Yes indeed - good lub oil would certainly help - and again, modern lubes are better still.

Speaking of working in the gritty, dirty steam era, that lesson was missed initially by BR with their Modernisation Era diesels and their operation...

 

I suppose you could argue that it was time and past time that the more rough and ready aspects of shed maintenance were tightened up on, and there were movements in that direction, but for those of us who do not hold an especial regard for OVSB its scarcely the only occasion where we might wonder about his location in the universe or choice of recreational combustible.

 

The specific issue of broken 'Leader' lugs was solved by the expedient of disconnecting the radial rocking motion, which was originally included to impart a 'figure of eight' motion to the sleeve, thereby improving lucrication.

Paul's comment concerning sleeve valves in automotive applications reflects my own understanding. The cussed things never did perform either well or reliably for too long. Several aircraft employed sleeve valves successfully, though it's worth noting that these operated in conditions far better suited to their characteristics. Like turbines, they're way happier operating at a constant speed for which their design is optimised.

Clearly, the nature of railway operations (with the questionable exception of long distance expresses) comes nowhere close to any notion of 'constant speed'. Recall that Stanier's 'turbomotive' No.6202 was habitually employed on London-Liverpool expresses, with its (forward) turbine optimised for 62mph. I somehow doubt that loco would've been too much more successful than 'Leader', had it been used on stopping services .... which doesn't exactly let OVSB off the hook, considering the planned usage of his design. Perhaps the next 'Leader' should employ variable pitch turbines. Or perhaps not!

Slightly related, from the current era, the US B1 'airplane' (best use their spelling!) is designed with operational speeds (and therefore temperatures) in mind and consequently, the fuel supply system leaks like a sieve when they're on the ground.

 

Is 'solved' really the right word here?

 

As right as any use of the term with respect to 'Leader' (e.g. it's attempt to asphyxiate the crew in Crowborough Tunnel!) , though s'pose 'worked around' could be considered a tad more .... appropriate. Anyhoo, the lugs certainly didn't keep snapping once the ocillating gear was discombooberated.

 

My grandfather owned a sleeve valve Minerva. Spoke very highly of it.

 

Absolutely not! Henry Royce disapproved greatly of the sleeve valve principle, holding that the heat generated by the combustion process had to pass throught the sleeves to be dispersed into the water jacket. As later generations would say, this was "asking for trouble"

 

Well I once met a Cdr. (E) R.N. Rtd., who told me that these engines had to be warmed up with enormous care or trouble would result.

 

It took the Bristol (Aero) Engine company many years to get a reliable product with sleeve valved engines. During WWll they were heavily leaned on by the Air Ministry to pass on the 'know how' to Napier for their Sabre engine to make that reliable. See the book about Sir Roy Fedden published by the Rolls Royce Heritage Trust for more information.

 

They were, but at the cost of a maintenance overhead that would be unacceptable for anything other than military aviation.

Its hard to find figures, but when my father was serving on HMAS Sydney in the Korean war she carried 1300 crew of whom less than 50 were the actual aircrew, for 2 squadrons of Sea Furies (sleeve valve) and one of Fireflies (conventional), and they typically did about 4 hours flying per day. When the same ship was used as a troop carrier the permanent crew was about 550, so presumably the difference is the number required to support the aircraft.

 

You can do some order-of-magnitude number crunching on that. (*)

The difference gives 750 people supporting flying operations. 50 are aircrew, so that leaves 700 in support. Let's assume 200 of those are involved in flying operations; that gives about 500 to support maintenance (but also including armourers and other trades not directly related to maintenance per se).

So that gives 10 maintenance crew to support every pilot; but if we assume pilots spend four hours per day flying but the maintenance crew spend eight hours doing maintenance, that means 20 man hours of maintenance for every hour of flying.

Again, thinking just order of magnitude: if you assume (at current values) something in the region of £25 per hour average staff cost for an aircraft fitter, that gives £500 per flying hour staff cost. Allowing for supplies, let's say direct staff costs represent perhaps a third to a quarter of actual flying cost gives a very approximate cost of £2,000 / flying hour at today's prices. To put that into perspective, the goal of the F-35 was to get to $25,000 per flying hour but reality seems nowhere close to that - perhaps $35,000 per hour being closer. The Sea Fury looks like a bargain!

(*) Please don't take this calculation too seriously: it is designed to test plausibility, not come up with precise figures.

Tom