Cyclone Power Technologies, Inc. (fka CYPW)

[BuddyWhazhizname]

Mystery Solved: Why Harry is screwing around with a rotary valve.

I thought Tom was onto something with his valve physics post. He found (and I agree) that to meet its published performance claims the Mark 5 engine must be able to open and close the admission valves in 0.0006 seconds or less.

That means accelerating the whole valve train, i.e., cam follower, pushrod, rocker arm, valve and valve spring, from rest to maximum velocity in one quarter of that time, then decelerating it to a stop at 0.0003 seconds, then accelerating and decelerating the valve back to the closed position in the other 0.0003 seconds.

Tom says (and I believe him here too) that valvetrain accelerations for pushrod engines are limited to 450 Gees (i.e., 450 times the acceleration due to gravity). This is the limit for mass production automakers that have the best materials and manufacturing processes available, maintain accuracies of considerably less than a thousandth of an inch and measure surface finish of parts to millionths of inches. A one-off cam would never be able to meet the same performance levels.

There's a video that shows the first Mark 5 prototype crankcase and cylinders running on steam in 2009.

Here are a couple image grabs from near the end. Note the position of the end of the rocker arm at the valve:


Assuming the fellow's knuckle is the same width as mine (3/4"), the valve travel scales out to 0.10" (well, 0.09836" to stupid precision...)

From high school physics: d = 1/2 x a x t^2

or a = 2 x d / t^2

where d = distance valve travels during accelleration (= 0.050")
t = time it accelerates (= 0.0006s / 4 = 0.00015s)

so a = 2 x 0.05" / (0.00015s)^2 = 4,444,444 inches per second^2
= 370,370 ft/s^2
= 11,500 Gees (with standard gravity at 32.174 ft/s^2)

This is more than 25 times what automakers will allow when designing engines for reliability.

But wait! It gets even worse!

The Mark 5 uses a single cam lobe on the crankshaft to operate all six valves. An auto engine camshaft uses one lobe to operate one valve, and the camshaft turns at half the crank's speed.

So the cam in the Mark 5 sees 12 times the number of cycles as a cam in a car engine.

But wait some more! It gets even worser!

Camshafts in car engines are flooded with high quality oil that contains anti-wear and extreme pressure additives. The Mark 5 lubricates (or not) its cam with water that has no additives. Perhaps water is slightly better than nothing. Or perhaps not.

So Harry Schoell, "technology visionary" and "ingenious inventor" designed an engine that requires the cam to tolerate 25 times the loads of a car engine camshaft, while opening valves 12 times as often, and without any lubricant.

It's not surprising that in all these years and with all the millions spent there has never been a public demonstration of a Mark 5 working. Even with the best materials on Earth, there's no way it will run at full speed for more than a few minutes without destroying the valvetrain.

This is why Harry recently took such a huge step backwards to put a rotary valve on the Mark 5.

This would also be why the OSU people switched the WHE from cam operated valves to a rotary valve. There's no way cam operated valves can be made to survive.