Radial engine cyclinders have fixed positions that radiate from the center of a crankshaft that turns within the engine.. Rotary engine cyclinders, and the propeller, rotate around a crankshaft that is firmly fixed to the enrire aircraft; The propeller of a rotory engine is attached to the engine. The propeller and engine rotate as one assembly. Both provide better cooling than inline cylinder engines. The rotory engine has wicked gyroscopic precession that requires very different piloting skills compared to other airplanes.

I don't think anyone is confused by that, at least on this channel. Interesting tidbit on rotary engines. Early model Mazda automobiles used a rotary engine type known as the Wankel. Little bit different obviously from aero engines, but I found working on them fascinating.

@@rbilleaud The Wankel engine, although termed a "rotary" engine, is an entirely different principle from the rotary aero engines used in the First World War. Those engines had pistons and cylinders, all of which, along with the crankcase, rotated and were attached to the propeller. The crankshaft was fixed to the aircraft's body. The Wankel engine has a fixed body. What rotates is a triangular piece inside geared to the power output shaft. There are no cylinders, per se. It is entirely different. The only similarity is the term "rotary."

​@powellmountainmike8853 that's what I kept thinking of. I didn't know there was two types of rotary engines

@@rbilleaud Mazda used the Wankel design of rotary-piston engine for decades (1967 - 2012, plus again starting in 2023), not in its earliest cars, and not just in early models.

They used cooling fan like that in J2M.

The photo of Ha-211 RU engine shows a cooling fan quite similar to the fan used by the BMW 801 installed on the propeller shaft.

The Germans traded technology for needed resources like metals.

@@enscroggs I thought the picture he showed was a BMW 801! I guess there are only so many ways to design a ducted fan.

The cooling air has quite a lot of energy after picking up heAt from the engine. With the right ducting, it can provide a small but useful but useful amount of thrust, which may have been part of the reasoning behind using this design.

I’ve been saying that wartime military development strongly resembles radiated adaptation, it’s an interesting phenomenon

Great point. I’m an evolutionary biologist, but husband in military intel and sims. Ancestors in opposing militaries lol. But ‘convergent evolution’ is fascinating. Hopefully you men, 90% of all geniuses will always be you as 90% of retarded, autism for instance, to cure aging and diseases like cancer, Alzheimer’s etc. The same imagination, scientific method etc, you would be surprised his many cures for ‘A’ actually resulted from research on ‘Z’. Please boys, keep up your interests and ideas.

@@ashbirk4681 Very true. Furthermore, these wartime developments often carry on less than optimal features for similar reasons seen in biological evolution. Whales drive themselves through the water by stroking their tail flukes vertically, whereas nearly all fish and the extinct Ichthyosaurs employ a horizontal side-to-side motion. Hydrodynamic principles suggest fish are more efficient swimmers on account of their horizontal tail motion. ( The flatfish -- flounders, sole, halibut -- are exceptions as they have traded efficiency for stealth.) Whales, however, have retained a spinal column evolved for fast running on land which doesn't really benefit their totally aquatic lifestyles. The overwhelming trend toward air-cooled radial engines in the Imperial Japanese forces can be viewed in the same light as the mammalian spine.

I must say, I think you may all be al talking balderdash. Evolution is a matter of random change, blind luck and trial and error. And that is conceding that evolution has a purpose - long term survival. of many species, In fact it has no purpose at all Engineering design is a matter of ingenuity in service of some Human goal . It is purposive. deliberate and goal driven. In war of course each side develops new machinery, tactics; exploits opportunities and defends against new threats existing platforms will change To cite some even clearer examples: Would you say that a fox is a better inhabitant of English woodland scavenger/hunter niche because its teeth are more evolved than simpler badger's teeth in other words the fox has passed through more near extinction events connected to tooth construction? Would you say that a Spitfire mk XIX is a better design than a Hurricane Mk III one as a fighter thee other as a fighter bomber - just because 19 is bigger than 3? oohh dratt. I think I get it now,, you aren't saying they are the same kind of thing. You you're' saying they are analogous. Right? Because there's nothing whatever the matter with whales tails. From Blues to Orcas they were all doing just fine until humans showed up. No doubt some were on the edge of extinction. There always are some like that , without that preessre there woiuld be no evoliution and no us. And I take the point about adaptive evolution though beyond the finches i cant think of a good example

That's Ki-94-I.

@@Teh0X - maybe so - but it was included with this video - which would obviously be confusing - specially when one had never heard of the KI-94-I

@@jonniiinferno9098 No doubt about it. Certainly a mistake.

@@jonniiinferno9098 Should have been included in this essay since it was one of the candidate bids for their "wunderwaffesu" fighter. Perhaps he couldn't find enough info or cut it for time, but the pic snuck in?

Same thought here. It looks like a push/pull design. And it's Pfeil (Arrow), ;)

Nope

Yes. The author does not know the difference between a rotary (fixed crankshaft) and a radial (moving crankshaft).

Did the Crntral Powers use rotary engines on warplanes? It might have been a spectacular episode to attack such a warplane with an S.P.A.D. It's 37mm would probably make short work with one good hit on the engine spinning at high rpm!!

@@martkbanjoboy8853 yes, they did. The Fokker Eindekker and Dreidekker both had rotary engines, to name but two.

The crankshaft is hollow. And fuel goes thru there.

Applies to a rotating engine - fuel is fed through the hollow crank - fixed solidly to the aircraft. Radial engines work like your car-engine and only the outputshaft rotates.

It follows that the conrods are also hollow, and the fuel-air mixture comes up through the middle of the piston? I think there's a spring loaded poppet valve in the piston crown.

Many were 2 strokes, or used the principle of passing the mixed fuel/air charge thru the crankcase to be drawn into the pistons from ports.

@@obsidianjane4413 I don't recall coming across any that were two strokes..

It didn't have a fan inside, and propeller was in front of the plane

Yes and the shutters at the rear could have been tuned to produce a net thrust like in a P-51 Mustang. With propeller cuffs the whole design could have become very efficient.

@@stevenborham1584 they were already doing that to late model zeroes

Or SAAB J21

The SAAB 21 deserves more notice in that it was in service for ~4 years. However it had a water cooled engine. It was also later converted to a jet engine design.

Yes, thanks. I was wondering. With RAF markings?

I expect the enemy would know which way you would break if attacked from astern, and would be waiting for it !!?

My thoughts exactly

Yup. A Sopwith Camel. The issue early on was cooling - with modest speeds of the early aircraft there was insufficient airflow to cool a (later) conventional radial engine so they solved the problem by having the cylinders rotate with the propeller.

How do you feed the fuel to the rotary cylinders?

@@onkelmicke9670 Through the hub.

​@@onkelmicke9670the crankshaft is hollow, supplying the engine with a fuel/oil mixture (the oil is for lubrication).

Not all were radials

Not all. The French firm Salmson built water-cooled radial engines with stationary cylinders like WWII radial engines. Anzani also built air-cooled radial engines, up to a 20 cylinder engine good for 200hp in 1913.

They'd have known about the BMW801 with its fan, and the Ki-61 used a licence-built DB601

@@thhseeking thank you. ☺️

Correct - no one uses this terminology for engines. Radial engines have radially-configured cylinders.

Yes, a cylinder every 40° in one row, and a second staggered to alternate with the front row. But like the vast majority of radials the Mitsubishi engines were four-strokes (with their design copied from Armstrong Siddeley and the Pratt & Whitney models), so only half of the cylinders fire on each revolution, and so there is a firing every 40° of crankshaft rotation. For more detailed information about the Mitsubishi Ha-43 (also known as Ha-211), you might be interested in the Old Machine Press article "Mitsubishi [Ha-43] (A20 / Ha-211 / MK9) Aircraft Engine". I suspect that some of the stills in this video came from the Old Machine Press article, or from the same source as that article.

@@brianb-p6586 it's a 4 stroke? Isn't that a nightmare to have to put valves all around? Wonder how the secondary imbalance in a radial engine acts

@@Rose_Butterfly98 Yes, almost all radials are 4-strokes. The conventional design uses pushrods run by cam rings that are placed around the crankshaft and gear-driven at half crankshaft speed. The pushrods push rocker arms to operate the overhead valves, just like any overhead valve pushrod engine (which the majority of engines built until the world switched to overhead camshafts). Some engines (such as GM and Ford gasoline truck engines) still use pushrods this way. It's a lot of parts, but in any four-stroke most of the complication is the valvetrain.

Four-stroke radials with a single row have an odd number of cylinders so they can have a regular firing interval. multi-row radials don't need that, and there are some four-stroke multi-row radials with an even number of cylinders per row; they need separate camshafts for each bank of cylinders because the common cam rings only work with an odd number of cylinders. But the Anzani at 0:55 does not have 6 cylinders per row - it is a 2-row engine with 3 cylinders per row. The rows are very closely spaced (possible due to large gaps between cylinders with only 3 cylinders in a row) so it looks like a single-row engine unless you look carefully.

@@brianb-p6586 oh you are right. it really is 2 row engine. also can you name any radial with even number of cylinders per row?

Thought I might be the only one never to have heard of cylinders referred to as rays. Guess I’m not crazy.

A better comparison would be the SAAB J21 that to my knowledge was the only WWII pusher prop design to enter service, it was later converted to J21R spec using the same jet engine as the Vampire

It's because of the type of paint they used and the method for affixing it to the airplane. It was actually an expensive and time-consuming process.

Which shows that the creator @IHYLS has no idea about WW1 aircraft engine technology nor about rotary versus radial engines ... The rotary engine *rotates* around the airframe and the propeller is fixed to the engine block. The radial engine is a normal engine ... just the cylinders are differently arranged from inline to V to VVVVV stuck together to a full circle. The rotary engine allowed much better cooling at the engine speeds common in the days, as the cylinders actively move through air and it could be built light and small. Heck, there is even the Monosoupape design (for rotary engines), which has only one, single, valve per cylinder. The fewer mechanical parts, the less can break. This special design has the drawback that the power can only be reduced by switching off the ignition for a bit (as there is no throttle to reduce the air+fuel input), wasting the fuel and oil normally used; advanced systems would automatically switch off a cylinder once, two or three times before allowing a combustion stroke, on top of the manual blip switch. There are even counterrotation designs, where the crankshaft and cylinder block rotate in opposite ways, either each driving a propeller (1906, Redrup) or only one propeller, connected to the crankshaft (1914, Redrup), albeit that was never got reliable for actual use. Another design (Siemens-Halske Sh.III) ran at effectively 1800 RPM, with cylinders and crankcase running 900 RPM in one direction and the other internal parts at 900 RPM in the other direction, giving a low running speed and a lot of torque. Growing power needs were mostly solved by faster rotation engines --- but the drag of the cylinders through the air raises exponentially, and is not sustainable. Radial engines have static cylinders, still provide the smooth power of rotary engines, are well capable of high RPMs without the drag rotary engines have, do not require a complete-loss oiling system, ... The Parisian Air and Space Museum has a cut model of an engine that shows the difference between rotary and radial by switching between the 2 different methods. Fix the URL in the obvious way. https: //vimeo.com/ 41546699 Radial engines still have the cylinders directly facing the flight wind and at speed will get considerable cooling, and will keep running even with a failed cylinder, no water circulation system to get busted, ...

@@advorak8529 Nice essay. I learned a few things. I have a couple of points to make. The crankcase of the rotory engine rotates around the crankshaft, not the airframe. It is true that early rotory engines had no throttle in the normal fashion that's why they used a kind of hit and miss way of reducing power. Later the engines were equipped with a slide valve carburetor similar in design to today's Mikuni models. Another problem with the rotory engines was the amount of torque the spinning engine imparted to the airframe. It was so much so that it killed a few fledgling pilots. With the clockwise rotation, it was easier to turn, bank and roll to the left as opposed to the right.