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August 1961 Popular Science
 [Table of Contents]
Wax nostalgic about and learn from the history of early
electronics. See articles from
Popular
Science, published 1872-2021. All copyrights hereby acknowledged.
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Dig those crazy curved pistons,
man. They are righteous! That was the sort of hip lingo just beginning to hit the
scene in 1961 when this "Rotary Engine Fires Like a Six-Shooter" article appeared
in Popular Science magazine. It was not a
Wankel type rotary engine
in that it still used pistons and connecting rods like a traditional internal combustion
engine (ICE). Looking as surreal as the watches in Salvador Dali's "The Persistence of
Memory" painting, the pistons' shape conforms to the arched cylinder in which
it reciprocates a few thousand times per minute. How someone thinks up a scheme
like this is beyond me. It took a couple readings to truly get a grasp on the operation.
The writer is a bit misleading when asserting that the pistons are not really reciprocating
in the cylinders, but in fact they are; they are just not driven by the traditional
crankshaft. The engine's configuration reminds me of a modern
brushless motor where
the armature remains fixed and the field coils (or magnets) rotate with the outer
shell. Some early rotary engines
used on biplanes had rotating cylinders. The
gyroscopic precession effect
during sudden control inputs were heck on the pilot. Like with the Wankel rotary
engine, the concept never caught on, or else we would see these engines everywhere;
instead we see them nowhere. Back to the drawing board.
Rotary Engine Fires Like a Six-Shooter
Both pistons and cylinders spin in this radical new power
plant for autos and lightplanes
By David Scott
It looked like a lump of metal impaled on a spit. An elderly man in a beret and
white coat wrapped the starting cord around one end and gave it a jerk. Exhaust
crackle filled the tin shed. Engineers from Ford, Rolls-Royce, Bristol-Siddeley
- the cream of Britain's auto-aviation society - sat up for a better look.
The action is pure two-stroke, like any outboard motor - yet the machinery spins
like a turbine
This was the rotating-cylinder engine invented by spry, sharp, 64-year-old Cecil
Hughes, and unveiled at a private demonstration near Southampton. Both its pistons
and its cylinders spin in circles. Nothing reciprocates - but the pistons seem to.
Have Your Cake and Eat It, Too. Because the pistons, in effect,
move back and forth within the cylinders, you side-step all the problems of sealing
and timing that afflict most rotary engines. But because there is no genuine back-and-forth
motion, you eliminate vibration and wear as neatly as any rotary does. Hughes' engine
combines the thermo-dynamic efficiency of the present internal-combustion engine
with the vibration-free, high-speed advantages of the turbine.
Simple Construction of first version of rotating-cylinder
engine is laid bare in disassembly. From left: spark plugs with wiper-contact tops;
cylinder head; two halves of block, each with six curved cylinders. At lower right
-laid out in a row-are the three segments that make up one sausage-shaped piston.
Reciprocating effect is achieved by spinning
parts at an angle. There is no true back-and-forth motion, yet parts shift back
and forth relative to each other. Swash-plate engine uses same idea, but only to
replace crankshaft.
Beret-Topped Inventor, Cecil Hughes, fires up
his strange engine for audience of industry experts. Hood removes exhaust fumes
- Hughes didn't bother with a manifold for prototype.
Some experts consider this radical power plant a natural for cars and helicopters.
It has 12 cylinders that deliver 12 power impulses per revolution. Smoothness and
low-speed torque equal those of a 12-cylinder four-cycle engine.
The Halved Block. The cylinders are bored into a drum-like block.
But the block is sliced into two drums, making two opposed sets of six cylinders.
Think of the revolving magazine of a six-shooter sawed across the middle and the
halves pulled apart, and you have it - except that these holes are curved.
Fitting each opposed pair of cylinders is a double-ended piston,
sausage-shaped and segmented. There are no piston rods or crankshaft. The center
segment of each piston is connected through a ball joint to the end of the spoke
of a spider - the hookup is similar to the Dipsy-Doodle at an amusement park.
How It Works: These drawings follow an opposite
pair of pistons through half of one complete revolution of the engine. Diametrically
opposite plugs fire at the same time (1) to balance forces. At the other end of
the cylinders, fresh fuel enters while spent gases exhaust.
Exploding fuel (2 and 3) tries to push pistons
along cylinders, but they can move in that direction only by spinning (out of plane
of paper). So pistons and block rotate, shifting relative positions. Completion
of cycle (4) brings ignition at other ends of cylinders.
The spider creates the effect of reciprocating action without really reciprocating
anything. Both it and the cylinder block rotate freely around the same stationary
shaft. But the spider is mounted at an angle (15 degrees), while the block is set
square. As they spin together, the ends of the spider (and the pistons there) move
relative to the block. (The action resembles that of a swash-plate engine [PS, Mar.
'58].) That is, the pistons do slide in and out of the cylinder bores. But this
back-and-forth motion is only relative to the block. The pistons never actually
reverse their direction, so reciprocating motion and its drawbacks are totally eliminated.
Harnessing the Horses. If you're wondering how they get power
out of this thing, there's an output shaft fixed to one flat side of the drum like
block. In operation, each explosion pushes the piston "forward" - along the cylinder
axis. But the piston can move forward only by going "sideways" - around the spider
orbit. That pushes the cylinder block around.
Hughes' invention is a wild one in other ways. Naturally, the engine is its own
flywheel, with that heavy block spinning constantly.
But on top of that it is its own distributor. The six spark plugs screwed into
each side are topped with pancake-like terminals. Each plug fires when its pancake
wipes across a stationary contact, one mounted on each side. These electrodes are
diagonally opposite each other, so diametrically opposed cylinders fire simultaneously.
This prevents unbalanced loads on bearings.
Then There's the Supercharger. In an ordinary two-stroke engine,
the undersides of the pistons sweep fuel and exhaust through the crankcase. This
job is a two-stroke, but its pistons have no undersides, just two heads. The prototype
uses a Rootes blower to pump in fuel (16:1 gas-oil).
Hughes, an experienced builder of racing engines, claims that his design cuts
friction losses by two-thirds. The experimental engine, he says, is "rudimentary,
built straight off the drawing board to prove the principle." Yet it worked immediately.
During the past year it has run more than 300 hours at speeds as high as 4,000 r.p.m.
"This 43-cubic-inch engine is capable of 12,000 r.p.m.," Hughes said, "and I
could easily pare its weight to 45 pounds. Cylinder bore could be increased to 61-cubic-inch
displacement in the same 10 1/2-inch sphere." An engine of twice the bulk would
have a displacement of 488 cu. in. - a real whopper. Hughes is also thinking ahead
to four-stroke versions, diesels, and dual units back-to-back on a common shaft.
The British auto scouts who witnessed the test run were obviously impressed.
Remarked one of the Ford engineers: "I wish I'd thought of that."
Posted May 17, 2024
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