LeRhone Monosaupape 165 HP WW1
I wrote a review some years ago on this engine. Everything in it is from FACT and not opinions. I have had personal use of one of these fine engines. It was a LeRhone Monosoupape 165 HP.
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First: The "Rotary-Radial" engine concept had been around and in use for
a decade or so before LeRhone added his improvements to the evolution of the R/R.
They were ALL 4 cycle engines. They all had 2 valves per cylinder, some had 1 pushrod operating both the intake and exhaust valves, some had 2 pushrods ditto. some had 1 pushrod operating 1 overhead exhaust valve and an intake valve in the top of the piston that was operated by a pair of counter balances and pressure differential that induced the entire fuel/air charge into the cylinder thru the valve in the top of the piston.
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Then LeRhone came up with the idea of MONOSOUPAPE (one valve) one overhead valve, and nearly as large as the bore. With NO manifold or restriction it should breathe well. He figured that after the exhaust cycle, why close the valve. Heck leave it open. The cylinder will be completely scavenged of any residual exhaust from the previous combustion, very desireable but impossible with a 2 valve system (unblown) And when the PISTON, now on its "Intake Stroke" gets a little past halfway down it will have filled the cylinder with fresh air unimpeded by a restrictive intake manifold and tight valve porting, "NOW" close the Valve. The remaining travel of the piston will cause a partial vacuum in the cylinder, and when the piston gets almost all the way down it uncovers a series of 1/8 th inch diameter holes drilled radially through the cylinder sleeve at a10 degree radial spacing (36 holes) and with a partial vacuum in the cylinder and (0) atmospheric pressure in the crankcase the "BALANCE" of the intake charge (with petrol) is drawn into the cylinder, completing the "Intake Stroke". The"Compression Stroke" is conventional and the power stroke differs from the norm only by the Valves' opening about 1/2 inch before the piston uncovers the 36 secondary intake ports, so the pressure will drop to a point where the exhaust gas doesn't pass into the crankcase thru the bypass ports and impede theintake process.
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I was instrumental in the procurement of one manufactured in the US in 1918 and sold as war surplus in Long Island City (1920) for $20.00. It was Crated & on an engine overhaul stand, w/fuel tank, lines, hand pump, gauges, firewall adapter, propeller, oil tank, plumbing pkg, hand air pump. And believe it or not a "Hand Crank" Every thing but the airplane.
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What became of that engine is a story in itself.
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Back to clarification of the "Monosoupape" cycle functions.
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The following is CC&P'd from this review. of 1998.. .
"I mentioned that the crankshaft was hollow. It was so, but not for weight saving reasons. It was the air intake for the fuel induction/injection system. The name :"Monosoupape" mono in French means "one" and soupape means "valve". This unique design had but "one" valve per cylinder. It had nearly a 5 inch bore and a single pushrod rocker arm operated, overhead mushroom poppet valve nearly the diameter of the bore. (4-1/2 inches).
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It was both the intake and the exhaust valve..Well 60% of the intake, the balance 40% of the intake charge was induced through the hollow crankshaft, crankcase and the 36 bypass ports. This 40% had to be a very "Rich" fuel/air mixture as the other 60% was all AIR....This arrangement gave extremely high BMEP (Volumetric Efficiency),
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It was a 4 cycle engine.. It is more easily understood when the cycles are described starting at the beginning of the "Exhaust Cycle" with the piston at the bottom of its stroke (BDC) the valve is already open, it opened when the piston was 1/2 inch before reaching BDC, relieving the cylinder of exhaust gas pressure before the piston uncovered the 36 bypass ports 1/8" in diameter.spaced at 10 degrees radially around the base of the entire cylinder, that communicated with the crankcase which was at atmospheric pressure. No transfer took place then, (no Pressure differential).. The piston now starts up, on its "Exhaust Stroke" the single overhead valve (still open) exhausts directly into the slipstream (no exhaust manifold) this saves a bunch of weight. Being the crankshaft doesn't rotate and the pistons don't go up and down in relation th the crankshaft. They simply orbit the stationary crank-pin in an eccentric orbit that causes "relative" piston travel and negates the need of crankshaft counterbalances. (the heaviest part in the engine) We are now talking about what made this engine (all R/Rs ) such high performers. "IT WAS THE NEAR ABSENCE OF INTERNAL INERTIA LOSS" The major engine components "ORBITED" and didn't "RECIPROCATE"
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The piston completes its exhaust stroke and when TDC (top dead center) is reached (the) valve does not close and being open to the slipstream 100% scavenging occurs and the piston starts down on its intake stroke, remember the valve is still open and fresh air from the slipstream intakes till the piston reaches 2/3 rds of the way down, at which point the valve closes and the remainder of the intake stroke causes a partial vacuum to form in the cylinder and when the piston uncovers the 36 transfer ports it intakes the balance of the intake charge as a result of the partial vacuum in the cylinder and atmospheric pressure in the crankcase. This "balance" of the charge being an overly rich mixture of fuel and air (air that was sucked in through the hollow crankshaft) and fuel which is injected continuously by a fuel nozzle on the end of a fuel line that enters the crankcase through the hollow crankshaft and the nozzle being in the proximity of, and aimed at the inside base of the cylinder where the 36 transfer ports are located. The next cylinder will be there to get its charge next. remember the fuel nozzle is stationary with the crankshaft. The next stroke being the compression stroke is conventional, the next is the "power stroke" and it differs from the conventional power stroke in that the Poppet exhaust valve opens just before the piston uncovers the 36 transfer ports relieving exhaust pressure and preventing exhaust gasses from entering the crankcase. Then we start all over again.
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The Monosoupape was only one of a dozen or so different arrangements of the rotary-radial concept. Many different valving systems.
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I didn't mean to write a darn book. Some of this is written now and some from my old reviews, that with my failing short memory will explain away the repititions. and overlapping thoughts.
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I hope you wil get some good from this. If you need any more, I'll chip in what I can....
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Cheers,
Ralph Lindsay
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The motion of the sleevee approaches Harmonic Motion, eliminating the inertia loss of the reciprocating sleeve(s) It Neutates, reciprocates and rotates 36°
Note: 2 small con rods drive the two sleeves in a reciprocating manner.