Our discussion of intake air velocity made me think of
an old British engine called the Cross rotary valve engine.
As I recall. Here is a sketch from memory I made.
When I was a kid I was fascinated by this engine.

The large bearing was necessary as the force on the rotary valve
was considerably during the combustion cycle.

Note the huge intake and exhaust ports unencumbered by any silly
poppet valves. This gave much more port area than a sleeve valve
engine.

The engine ran well and probably was the most successful of a long
list of rotary valve piston engines including one designed by Felix Wankel.

Problems are cooling the valve, sealing  and the opening and closing
times as the valve rotated at 1/2 crank speed just like a cam shaft.
Also deflection of the valve might cause rubbing on the cylinder head.
The spark plug rotated along with the valve. Bulk in the cylinder
head was also a problem.

I think perhaps with modern materials such titanium for the valve
this engine may have a few possibilities. If the rotary valve is slammed
around electronically to index the ports as required the timing problem
could be over come. In fact the opening and closing times of both
intake and exhaust ports could be closely controlled by a computer.

I am not naive enough to think this will ever be tried but be wary
of some shyster selling stock to develop this engine. I would say
its chances of succeeding are at least 1000 to one and maybe
as much as one million to one :-)

Paul Lamar

Here is a bit of back ground on the Cross engine with an illustration
from a patent.

http://www.lortim.demon.co.uk/Aspin/

Paul Lamar

And a better, more practical illustration showing a method of cooling the

rotary

valve. This patent expired years ago.

Paul Lamar

If you tuned the intake and exhaust you could get some awesome
volumetric efficiency numbers.  We get so used to having a port
obstructed with a poppet valve. . . .

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

 
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