Originally Posted by
Beez51
GeeRam,
I can't find the thread but there was a discussion on the Centaurus and the rather specific nature of the oil required some time ago on PPRUNE. I copied the details for my own interest. I don't know who wrote it and apologies to however did if what I copied is not accurate. Here it is:Re Centaurus Sea Furies, No one in Europe since Hoistler Gmbh in Germany, has an interest in maintaining Sleeve Valve Engines. Ricardo in Shoreham did the last RNHF Overhaul, and it cost so much the Engines now go to the States. However, the States as already stated are putting anything from 3350 t0 4800 P&W's in, because the remanufacture of the Sleeves is not financially possible. Getchell Ellesworth has looked at it at length. In the 70s when I was heavily involved with this, I received a midnight knock on the door, to find both Frank Sanders and Getchell standing in the rain, asking to come in. The RTO from Rolls Bristol, Johnny Danes and Buster Paine, and myself were looking at cobbling one serviceable engine from 3 Time Ex Ex Hoistler ones. They had civilianised the Spec to replace the long Piston with oil control ring below the gudgeon pin, with the Slipper type from the Bristol Hercules, which was identical in bore and port profile. This meant a lot less stress in the rotary gear that operated the sleeve drive, that caused so many failures. They looked at the pistons we had extracted and miked them up, and went off to find a source for Hercules Pistons. The Americans (Lloyd Hamilton), had tried chroming the bores, like P&Ws, but after ground running for hours on end, could not get the engines to bed in, even with cast rings. The Sleeves did not appear to be concentric, but had a slight polygonal inner surface, like modern semi automatic pistol barrels that have no rifling, and thus are incredibly difficult to remanufacture. The only alternative was to fit a Corncob derivative. Frank and Lloyd were the first to do this, and everyone else followed, except Getchell Ellesworth who has persevered. There is another problem, and that is lubrication. Sleeve Valve engines use a very different spec oil-100U-A heavy detergent oil which allows burnt oil dross to stick to the clearances of the moving parts, and fills its own gaps, without having to have tighter tolerances. Thus, the complexity of the moving parts is kept together. If a straight oil is used, or even a W, this Oil residue is flushed out into the filters and is lost, thus a lot of metal to metal movement occurs, causing too much wear. Shell has not made this for decades, until a batch ordered from Chris Fear by me, for RNHF in '76, coinciding with a RNZAF Order for their Freighters, and RNHF again in 2000. The mod for fitting P&Ws is quite straightforward, but can only use the Hamilton 4 Blade Prop. They have a never ending supply of these, so that is the only way Sea Furies can be maintained. The other Sea Fury problem the Bag operated Pneumatic brakes-These are the same as Meteors, and no longer exist, apart from M&B at Chalgrove. Thus, Lloyd and Frank modified F102 Brakes and Wheels (Same section and diameter), and the rudder pedals to give Hydraulic Brakes and a safe landing. Sorry this is a bit off thread, but Sleeve Valve knowledge is dying out, so I have tried to explain the problems. Stephen Grey may have the wherewithal to remedy this, as he goes to great lengths to be original.
regards Beez