A real rotary engine! Finally a video that mentions a rotary and doesn’t mean a Wankel engine! Thank you, these engines have always interested me, would love to restore one.
@@Smokeybear69420 Agreed, it's getting harder and harder to find rotary engine content when everybody's calling friggin' Wankel engines "rotary engines" when they aren't rotary engines at all.
@@spetsnazGru487 Nope, you’ve got it mixed up. Radial engines have stationary pistons, rotary engines rotating pistons, a Wankel engine has a “rotor” but is not a rotary engine.
Thanks for the great explanation of its operation. In my High-school days I was into WWI aircraft in a big way and when discussing engine types in Autoshop the Instructor berated me for telling him about a rotary engine where the full engine rotated around a fixed shaft as he was only familiar with radials and they made sense to him. Well, I kept my mouth shut after that but I knew he was dead wrong!
You should have gone on to tell him about needing only one valve per cylinder, because it can both expel exhaust gases and suck in fresh air at the same place if you have no carburettor. That would have made him mad and he would have sent you to the principal. Your teacher sounds like a couple of real clots I had in high school, such as the science teacher who told us there are three states of matter in thermal sequence - solid, liquid, and gas. I told him there is a forth state - plasma, at which he flatly declared I had made that one up.
One of the best antique airshows is at Old Rhinebeck Aerodrome north of New York City near Kingston, NY. They fly a variety of authentic aircraft dating as far back as 1909.
One of the reasons that World War I aviators wore scarves is to keep them from having a severe case of diarrhea after flight: these engines were designed to be lubricated by castor oil. With open rockers, your face got covered with oil by the end of the flight. So caps, goggles and a scarf were important to keep you from injesting large quantities of castor oil 😉
I would love to see some diagrams of that fuel delivery system. I have a good mechanical mind and it feels like some 2 stroke elements going on here. Very interesting.
Induction to the cylinders is similar to that found in two-strokes but relies on suction in the cylinders rather than pressure in the crankcase. The earliest Gnôme engines had suction-operated intake valves in the pistons. Later this design was abandoned in favor of induction ports in the cylinder skirts. Since the crankshaft and crankcase also serve as the induction system, oil was mixed in the fuel and blown from the exhaust, again similar to two-stroke operation. These were four-stroke engines, however.
Amazing technology for it's day! I'd suppose the fuel gets fed in through a central tube at the back. However the rotating crankcase made it into a gyro, which in turn made the plane very hard to control. It tends to roll to one side very easily, but to roll to other side takes a lot of effort and muscle power. This is coupled with the fact that these engines are either in idle or in full throttle.
Agreed, however a twin with counter rotating Gnomes would be... interesting! Victorian answers to 20th century problems, I love Gnomes. "It's gets too hot, well just spin the whole mill. Righto!"
Note: Further viewing of this engine actually flying demonstrates the cunning newly invented 1/2 speed position... by using modern electronic spark control to cut out every second ignition pulse... allowing a steady state half throttle for cruising....
Excellent discussion - thank you very much! Can't say how much I appreciate outfits like this building working replicas of such historic engines. So see, hear (and smell) one running a century after they ceased to be used is just amazing. Gotta hand it to the original designers - the Gnome and Rhone engines and their Oberusel clones powered important aircraft right through World War One.
This type of engine had the best power-to-weight ratio at the start of the war, in addition well balanced, these engines did not vibrate, the only problem was that the rotation speed was limited, therefore ultimately the power
@@CheshireTomcat68 Correct. They claim that the pilot's seat was wicker to save weight, but the truth is that it was woven wicker for drainage. The other main issue/idiosyncrasy of the gnome is that it is either off, or at full power. If you look at the control stick for a rotary powered fighter from WW1 they will all have a small momentary switch on them that interupts spark. They called it "the blip switch." Turning off ignition for a moment was how you would throttle back the engine. You can hear pilots doing this as they come in to land.
Oil is pumped into the engine. It has two supplies, one to the master rod and another to the cam pack. It mixes inside the crankcase and then out through the cylinders.
I believe it was developed for the perpose of allowing long wait times on the field to await the signal to take off, without the problem of overheating.
Monosoupape literally means one valve. So that explains part of the engine. But I think it also had a butterfly/reed valve, in top of each piston. So it would suck in fuel and air mixture through that butterfly valve in the the piston, and then the exhausts would be released through the single real valve in the top. Real valve, as in being controlled by the cam. But I might be wrong here. I have some vague recollection that the piston valve was not really needed, and it kept jamming, because of the stickiness of the castor oil used for lubrication. So the Monosoupape version, that is the single valve version, might be a later version that did away with the piston butterfly/reed valves. And used ports in the cylinder walls instead, like a two stroke engine. Which would make the name make sense, pointing out that we now only have one valve, the reliable one, and have gotten rid of the troublesome piston top valve. I'll have to google for this info some day in the future... 🙂
If you've ever been around world war 1 era rotary engined planes they sound weird when they come in for a landing. Remember there's no throttle so either it's on full power or it's off. The pilot will line up with the runway and turn off the engine. They loose speed and the pilot turns the engine back on to gain a little bit more power then cuts it off again. The prop windmills when the power is cut so restarting is easy. Eventually they land and the engine stays off.
Awesome explanation...but how much gyro effect when the plane turns since the whole engine rotates and secondly how does the engine gets spark to the plug while the engine rotates
Hi David, have just put up a short video taken from the side which clearly shows the ignition wires. Its called Short video of Gnome running from the side (short). Gyro did have an effect, turns better one way.
There’s a contact and when the cylinder is in position it touches a switch that completes the circuit and fires every other cylinder as I understand it
Electrodes on the back line up with the coil wire electrode as the engine turns. As a cylinder lines up it's electrode to fire, the points in the mag open and that cylinder fires.
I’m not sure how true it is but I heard these rotary engines were made because early attempts at radial engines couldn’t keep the cylinders cool effectively enough so they made it so the entire engine rotated to create better air flow over the cylinders. Obviously this problem was solved due to the reemergence of static radial engines but I’ve never found what actually made them dissipate heat better.
I too wondered this for the longest time, so I'll share the answer with you. Notice how relatively small the cooling fins are on this rotary engine vs the much larger fins on a typical radial engine. The cylinders of a radial engine are made of cast metal. However, the casting technology of the early 20th century was not up to the task of reliably casting the large cooling fins that would be needed for a high power radial engine. They could manage small cooling fins, but those cooling fins are not large enough for a 100 hp radial. If you have the cylinders spin, like a rotary does, those small cooling fins are suddenly getting enough airflow through them to keep a 100 hp engine cool. As casting and other manufacturing technology improved, it became possible to make cylinders with large enough fins that radials became viable.
@crosshair84 - Process Engineer here: your explanation is wrong. Those fins are not cast. The cylinders are cast and then the fins are *machined* in a lathe (in the case of air cooled engines with a different geometry the cylinders are machined in a milling machine). I believe that the reason for doing rotary radial engines such as this was because they consume less resources (time, raw materials and tools) and therefore they are cheaper and faster to manufacture than a stationary radial engine.
An obvious attempt to troll doktorbimmer, who is probably miserable, considering Mazda has confirmed they are bring back their wankel engine as a range extender.
I heard that those engines slung oil all over the place, I may be wrong. How was the engine lubricated? Did it have some kind of oil pump or was the oil slung around in the crank case?
Complete loss oil system. Used castor oil and slung oil all over which is why you see them with cowls nearly enclosing them. It also made the planes even more flammable.... Ah WW1, the enemy is trying to kill you, your side is trying to kill you and your own equipment is trying to kill you. Good times.
Here’s another video that answers the question: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-N2BKbpTmQbw.html look at the side of the cowl at the start of the flight and then again at the end. You will see oil leaking back nearly to the cockpit by the end of the 10min flight.
The Millet type Rotary has some unique advantages over conventional layouts at the time, They are lighter and much smoother running (vibration free) with no need for a heavy flywheel. Pilots liked them because they could take off almost imediately after starting without any warm-up. The main reason why they fell out of use was as the engine gets bigger its effects on gyroscope procession became a flight control problem.
So induction is by slip-valves much like a 2-stroke but with exhaust being via the single valve? And the crank carries the fuel-air mixture to their sump, so is it mixed with lube oil like a 2-stroke? Else how is the engine lubricated?
@@classicaeromachiningservic262 actually this was an issue even in normal operation since many pilots died during training during phases such as takeoff and even performing basic turns!
@@rahulbhatia7798 You are correct that many died during take off while learning to fly but remember that as well as learning to fly they also had to learn how to run a engine. Its not like today engines when you turn the key and they run. Rich cuts were common and could take 10 to 15 seconds to clear which if you had just taken off that had dire consequences.
I know this engine tech was short lived, but at some point did they find a way to control engine power? As many on this noted, it either full power or idle
Some manufacturers were developing carburetors with throttles mounted to the hollow crankshaft but Rotary engines were quickly reaching the limits of their potential.
Hi Tom, its a 4 stroke. It uses transfer ports at the base of the cylinder like a 2 stroke but it is a 4 stroke. In the crankcase it has a very rich mixture of fuel oil and air. The one valve at the end of the cylinder opens on the induction stroke and it sucks in clean air. About 2/3 of the way down the induction stroke the valve closes so as piston gets closer to bottom of stroke there is a vacuum in the cylinder. Piston gets to the bottom of the stroke and exposes a ring of holes and the vacuum sucks in some of the rich mixture in from the crankcase. Piston goes up, mixture compresses and fires as per a normal 4 stroke. The valve on the end of the cylinder opens and allows exhaust gases to escape. This valve stays open right through to the induction stoke. Its a very simple system. Hope that helps.
"How the Gnome rotary engines works" Not too awfully bad, but imagine the gyroscopic effect on control of the aircraft. Those WWI pilots had to be well-trained! 1:06 - Strange to see obvious CNC tool paths on parts of a >100-YO engine!
@@danweyant4909 cylinder ports are used on other types of 4-stroke engines as well, The Knight type sleeve valve engines come to mind... it is not unique to 2-stroke engines.
@littleshopofelectrons4014 No The camshaft rotates at half the engine speed opening the valve every second revolution. The valve Opens just before BDC and closing just after TDC producing lower air pressure in the cylinder. The piston travels down and uncovers the transfer ports and sucks in the fuel and oil mixture from the crankcase. The piston travel up compress the mixture the magneto spark fires at just before TDC. Watching video of these engines running sometimes you can hear them firing on one or two cylinders due to some part in the top of the cylinder being red hot from a too lean fuel mixture. Watch this video @ 1:55 to hear this ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Hq78ZocOAkY.html
World War I pilots inhaled and swallowed a considerable amount of castor oil during flight, leading to persistent diarrhea. Perhaps this is why WWI pilot uniforms were brown.
Yes. In practice if a pilot in a Camel wanted to change direction 90 degrees to the left, it was easier and faster to simply do a 270 degree turn to the right.
History fact: the man who invented the rotary engine-rather than squat as per convention and common sense- preferred to lay down on his stomach whenever had to take a crap 💩.
Brad Brown I’m not sure, but according to multiple accounts, when people insisted to him that a crankshaft should move and crankcase remain stationary, (not the other way around), he replied “aww shit..”
just stack two of them, gear them oppositely, give them own prop, doubling the HP and eliminating the precession issue. ...no one has the balls to try this????????????
It was originally mainly a weight issue. At the opening of WW1 a 50 pound increase in carrying capacity for a fighter was seen as major upgrade and up to a certain point a true rotary engine provides a better power to weight ratio than a radial engine. Of course this eventually hit an engineering brick wall when engines got so powerful you'd have to spin the engine at damn near supersonic speeds.
I'm no expert, but I can imagine a couple of potential mechanical benefits. With this configuration, the pistons all spin around a fixed point instead of reciprocating, so the vibration transmitted to the extremely light and flimsy airframe was probably reduced a fair bit, and there was likely no need of a big balance weight on the crankshaft, possibly making the engine lighter at a time when there really was no weight capacity to spare. With the whole engine block whirling around like that, it would also have probably acted as a very good flywheel, which would make the engine less likely to stall and die if there were any hiccups in the fuel supply or anything like that - given that there was no way to restart the engine in the air if it stopped (except, just maybe, going into a steep gravity dive to spin up the propeller in the slipstream and praying the damned thing restarted with enough altitude left to then pull up before you hit the ground!), this probably made the whole rickety thing more reliable during landing and take-off - especially because there was no actual throttle on some of the early planes; to cut thrust enough to actually land safely, you had to "blip" the engine, and a decent flywheel inertia probably improves your odds of the "blip" (or even throttling down) not becoming a dead stop. Whirling those finned cylinder heads around probably increased the air cooling effectiveness, too.
Flying is inherently dangerous. Add a wood framed fuselage and wings, add 30 gallons of fuel, add being shot at with .50 caliber machine guns, and top it off with this 100 HP motor. Then a life expectancy measured in weeks makes sense.
@@connarcomstock161 There are 4-stroke engines that have No poppet valves. Invented by American Charles Knight in 1905. They were massed produced for several different automobiles and aircraft Most notable were the Willys-Knight cars and aircraft like the Hawker Typhoon and Tempest
