Here’s an aviation application where a Wankel powerplant has established a good reputation.
What a horrible animation. Although, to be fair, the animation is intended to illustrate the four IC cycles, not the exact linkage motion. Here’s a better animation for motion analysis.
While I don’t disagree with anything else in your post, the maximum force from inertial load of the piston occurs near the top and bottom of the stroke. Velocities are maximum near the mid-stroke; accelerations (and inertial forces) are near zero at the mid-stroke and maximum near the ends.
I wonder why the Wankel hasn’t been adapted for small, 1 or 2-cylinder engines, like power mowers or even motorcycles. Could it be that compared to a garden-variety Briggs & Stratton lawn mower engine, it’s not as reliable or cheap? It would be smoother and perhaps quieter, wouldn’t it? How about smaller and lighter?
The B&S engine is extremely simple. It doesn’t even have overhead valves. I would not expect a small Wankel to be either as cheap to build or as reliable to run under the low or no maintenance conditions that most mowers see.
Can a Wankel be air cooled efficiently?
>I wonder why the Wankel hasn’t been adapted for small, 1 or 2-cylinder engines, like power mowers or even motorcycles.
Perhaps it’s the issue someone brought up earlier about having too much surface area per volume for the combustion chamber, causing excessive heat loss from the gasses to the walls and therefore lowering efficiency. This situation gets worse as the engine is scaled down in size.
There’s one for model airplanes. O. S. Engines 49-PI Type II 0.30 cu in Wankel. From what I see on model aircraft boards, it also runs hot and gets poor fuel economy. Otherwise, it sounds great!
>Perhaps your engines work differently from this Otto cycle animation.
That animation is all kinds of wrong at the limits.
In drafting class as a project, we fully modeled a 6 cylinder piston scheme from the camshaft up to the valves. We did plots and traces, and animations, and the pistons definitely do not slam to a stop. Assuming that there is no slop in your bearings or linkages, the travel is continuous and approximates a sinusoid (and is exactly a superposition of sinusoids).
That is so cool. I checked the site for other engines and they have an inline four and a flat four that look like aircraft engines. the flat four gets 4.1 hp per 4.9 lbs.
That’s a perfect application because you’re not carrying a lot of fuel so economy is not an issue (said the guy who swapped an O-320 into a Piper Colt).
I thought the main weakness of the Wankel engine was NSU themselves, who didn’t engineer it very well and ruined themselves with warranty obligations AFAIK.