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But my dear chap, it had a sprung to un-sprung weight ratio one could positively die for. He actually argued that motorcycles could have two flat wheels like from an F1 car and sort of slide around corners with the bike "almost" upright. OK that's a great idea, after you Mr Setright.Sounds like a group build theme.
Noteithstanding its decades of operating Bristol radials between the wars, The FAA does not appear to have been satisfied with their sleeve valve Bristols. Other than the short runs of the Albacore and Skua everything else is Bristol ohv engines or liquid cooled V12s until the postwar Sea Fury and the sv Centaurus. Perhaps the Hercules would have seen FAA and wider RAF service had it been an ohv design. I'd expect the ohv powered Swordfish would have been entirely replaced by the Albacore if the latter had a reliable engine.I find it interesting that there are many who criticise the complicated, unreliable Hercules and there are quite a few examples of pilots flew them and mechanics who worked on them who say they are amazing reliable and easy to work on.
The sleeve valve, however attractive it looked in the late 20s or early 30s became a solution to non existent problems by the late 30s or early 40s.
The actual cost in either money or manufacturing time of sleeve valve engines has been shrouded in secrecy not only during the war but ever since.
This makes evaluating the designs difficult and trying to figure out if alternative designs would have better even more difficult.
Bristol did the sleeve engines to work and work well but since neither the R&D cost or cost of the engines (or cost per horsepower) is known it is almost impossible to say what would have happened if other paths were taken.
The sleeve valve, however attractive it looked in the late 20s or early 30s became a solution to non existent problems by the late 30s or early 40s.
There are many ways to make an engine, 2 1/2 HP from a 290cc engine is as close to nothing as you can get. A 50cc moped makes 5HP.I'm reading the history of British motorcycles and came across the Barr and Stroud sleeve valve motorcycle engine. If well made I can see the advantages.
View attachment 614105
I'd reserve your disdain until you have an accurate point of reference. It's rated at 2 1/2 HP under the RAC tax system. That's doesn't mean it produces only 2 1/2 bhp. I expect its actual output to be closer to 12-15 bhp, totally respectable for a sub 300cc engine from the 1920s.There are many ways to make an engine, 2 1/2 HP from a 290cc engine is as close to nothing as you can get. A 50cc moped makes 5HP.
I'd reserve your disdain until you have an accurate point of reference. It's rated at 2 1/2 HP under the RAC tax system. That's doesn't mean it produces only 2 1/2 bhp. I expect its actual output to be closer to 30-35 bhp, totally respectable for the 1920s.
The RAC tax system is why many British car and motorcycle engines were long stroke, narrow bore machines, leading to industry-wide limitations later.
Yes. I was referring to the 998cc Grindlay-Peerless V-Twin, running the B&S sleeve valve, pictured above. A typical litre bike of the 1920s produced about 30 bhp, whilst the pricey and speedy ones like the 100 mph Brough Superior SS100 were good for 50 bhp.30 to 35hp would be blinding for an air cooled 290cc 4 stroke single today. 10 to 12hp would be more like it in 1919 on roughly 45 octane petrol.
Yes. I was referring to the 998cc Grindlay-Peerless V-Twin, running the B&S sleeve value, pictured above.
Indeed. Here's my 1969 Triumph 500 with front rear drum brakes. Stopping in the rain took some planning and engine braking. The brakes were even worse in the 1920s, and as you say, rear suspension was a rare thing.Even 10hp is exciting when you have no suspension and brakes and tyres that would be considered poor on a modern shopping bicycle.
True, the 8" TLS front brake was said to be one of the very best front motorcycle drum brakes. I could stop hard, when dry and of course there's no brake fluid or hoses to fiddle with. It was a good bike, here I am riding with my club. But after eleven years and three rebuilds it was time to sell and get something newer.At least you haven't got the BSA/Triumph conical front brake that the accountants inflicted on riders from 1971. They are a sick joke of a brake.
I had a T120V (drum brakes) and a T140V Disk front. I have owned reed valve two stokes, disk valve two strokes, OHV SOHC and DOHC four strokes a friend of mine had a Wankel rotary Norton and I saw them raced. There have been all sorts of engines, like stepped piston, rotary valve engines, desmo engines. If you don't need to produce a lot of power almost anything can work.Indeed. Here's my 1969 Triumph 500 with front rear drum brakes. Stopping in the rain took some planning and engine braking. The brakes were even worse in the 1920s, and as you say, rear suspension was a rare thing.
Back to sleeve valves, some of the advantages described here Grindlay Peerless - Wikipedia. Given innovative engine, I am surprised they didn't also add a rear cantilever suspension like some other high end makes of the time.
Reliability is one thing, but what about oil burn or leaks?View attachment 614152
The Perseus (the first Bristol production sleeve-valve) appears in its first 2 years of service to have no worse reliabiliy than the Merlin. Sadly I have not got these reports later than Dec 1937....
Oil burn? I think that is what you get with high performance piston engines in the 1930s.Reliability is one thing, but what about oil burn or leaks?