Editing Rotary engine (section)

===Monosoupape rotaries===
It is often asserted that rotary engines had no [[throttle]] and hence power could only be reduced by [[Kill switch#Vehicles|intermittently cutting the ignition using a "blip" switch]]. This was only true of the [[Monosoupape engine|"Monosoupape"]] (single valve) type, which took most of the air into the cylinder through the exhaust valve, which remained open for a portion of the downstroke of the piston. Thus the mixture of fuel and air in the cylinder could not be controlled via the crankcase intake. The "throttle" (fuel valve) of a monosoupape provided only a limited degree of speed regulation, as opening it made the mixture too rich, while closing it made it too lean (in either case quickly stalling the engine, or damaging the cylinders). Early models featured a pioneering form of [[variable valve timing]] in an attempt to give greater control, but this caused the valves to burn and therefore it was abandoned.<ref name="nahum44">{{cite book| last = Nahum| first = Andrew| title = The Rotary Aero Engine| year = 1999| publisher = NMSI Trading Ltd| isbn = 1-900747-12-X| pages = 44–45 }}</ref>

The only way of running a Monosoupape engine smoothly at reduced revs was with a switch that changed the normal firing sequence so that each cylinder fired only once per two or three engine revolutions, but the engine remained more or less in balance.<ref>{{cite book | last = Donovan| first = Frank |author2=Frank Robert Donovan  | title = The Early Eagles | publisher = Dodd, Mead | year = 1962 | pages = 154 }}</ref> As with excessive use of the "blip" switch: running the engine on such a setting for too long resulted in large quantities of unburned fuel and oil in the exhaust, and gathering in the lower cowling, where it was a notorious fire hazard.