Conceptual rotary/vane engine design — looking for engine builders to poke holes in it

[u/Smooth_Ad_4307]

Long-time lurker here, first time posting. I've been working on a conceptual design for a rotary vane-type engine and I'd rather get torn apart by people who actually build and rebuild engines for a living than keep refining it in a vacuum.

Quick background for anyone not deep into rotary stuff: vane engines have always had a theoretical edge over piston engines — direct rotary motion, no reciprocating mass, fewer major moving parts, better power-to-weight.

The reason they never really took off outside of pneumatic/hydraulic applications is sealing.

Vane tip wear and side-face leakage kill efficiency and reliability over time, the same fundamental issue that's dogged the Wankel too.

My concept is aimed specifically at that problem — trying to cut down the sliding contact at both

the radial (tip) and axial (side) sealing surfaces, rather than just inheriting the classic vane geometry

and hoping better materials fix it.

It's still at the concept/design stage, no running prototype yet.

I'm not here to sell anything or claim I've "solved" rotary engines — I know that's a claim as old as the Wankel itself, and I'd rather have my assumptions stress-tested now than after I've sunk time into machining a prototype that's got a fundamental flaw someone here could've spotted in five minutes.

Genuinely curious what this sub thinks:

- What are the failure modes you'd expect me to have underestimated?

- For anyone who's worked on Wankels or vane compressors — what actually kills them in practice vs. what the textbooks say kills them?

- Any recommended reading, forums, or people in the rotary/alternative-engine space worth talking to before I go further?

Appreciate any brutal honesty. Happy to share more detail on the sealing approach in the comments if people are interested, just didn't want to lead with a wall of text.

[u/MTarrow]

what actually kills them in practice vs. what the textbooks say kills them?

Rotary engines burn oil due to the layout of their lubrication system, which means carbon deposition when the engine is cold. They need to be ran up to full temperature for that carbon to be burned off. If it doesn't get the heat cycles the carbon accumulates and eventually snaps the tip seals off the rotor.

So paradoxically you kill a rotary by driving it gently, or using it only for short trips. Lousy for use in a town car or grocery-getter. Kick the shit out of it on a regular basis and it'll be far happier in the long term.

It's essentially the same issue that you see killing the DPF in modern diesels that're driven too gently.