Happy 50th Birthday ............. Wankel !!

[Matra et Alpine]

NSX, the big advantage teh DKM has is that NOTHING rotates concentricly.
So thus there are no out-of-balance rotational masses.
Thus in theory it can rev out to the point the castings shear

Think how fast a jet trubine revs to ... or a turbo. WHen it's all in balance rpm can be VERY high --100s of thousands
(practically however the first limit of a real engine is the intake flow rate and the second limit the speed of the combustion wave front)

[LandQuail]

3 years ago I did an essay about the Wankel rotary engine.

Happy birthday then, I guess...

I gave a class presentation on the wankel way back in a high-school class.

Here I am now, all these years later, and was asked a couple days ago to speak to a class of writing students at my old university. I love basking in my own glory.

[NSXType-R]

NSX, the big advantage teh DKM has is that NOTHING rotates concentricly.
So thus there are no out-of-balance rotational masses.
Thus in theory it can rev out to the point the castings shear

Think how fast a jet trubine revs to ... or a turbo. WHen it's all in balance rpm can be VERY high --100s of thousands
(practically however the first limit of a real engine is the intake flow rate and the second limit the speed of the combustion wave front)

Sure, a jet turbine or a turbo can rev to very high. But compared to an engine, there are so much fewer moving parts. All I count are fans.... and maybe more fans? Meanwhile an engine has stress from all over the place- valves, counterbalances, a crankshaft, a piston flailing around in different directions. Meanwhile, all a fan has to do is..... spin?

I'm not saying it's not possible. It's just that the stress that everything goes through sounds a bit much. And yes, it sounds more probable with a rotary also because it has fewer parts.

[Matra et Alpine]

I'm not saying it's not possible. It's just that the stress that everything goes through sounds a bit much. And yes, it sounds more probable with a rotary also because it has fewer parts.

In the original Wankel DKM rotary everything DID just spin round.
NO valves,
NO counterbalances,
NO offset crankshaft,
NO piston flailing around in different directions.

It was the "improved" KKM that we know today which is more complex.
But even only has a small offset "CRANK" needing counterbalance on the crank---- nothing opening/closing or flailing

[LandQuail]

Well, there is reciprocation. The rotor spins in an eliptochoid curve (or some word very similar to this one) which basically means a figure eight. As the rotor spins, it does go from side to side, which makes some vibration and stress on the bearings.

[NSXType-R]

In the original Wankel DKM rotary everything DID just spin round.
NO valves,
NO counterbalances,
NO offset crankshaft,
NO piston flailing around in different directions.

It was the "improved" KKM that we know today which is more complex.
But even only has a small offset "CRANK" needing counterbalance on the crank---- nothing opening/closing or flailing

How is it possible not to have valves? That would mean it's not even a four stroker, it's just a two stroke engine.

[Matra et Alpine]

How is it possible not to have valves? That would mean it's not even a four stroker, it's just a two stroke engine.

In the Wankel the combustion chamber "moves" round.
So it moves across openings whcih are intake and exhaust at different stages. It doesn't need reed valves as in a 2-stroke.
The terms 2 and 4 stroke kind of only apply to reciprocating pistons as it is the number of times the piston moves up and down in the cylinder for a single combustion cycle.

[h00t_h00t]

I don't understand why that design was scrapped, it seems that the extra complexity was well justified. Today, having inaccessable sparks plugs is of little worry when Mercs run around with plugs that claim to last up to 80,000 miles between changes. RX-7 rotarys were liable to blow at around 60k so its an awesome improvment.