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Did you guys know Pratt and Whitney is working on rotary engines?? There are lots of recent (2010-2018) patents related to or mentioning wankel rotary engines.
They have patents for rotors, apex seals, intake and exhaust ports, direct injection with pilot chamber, compound setups (turbine connected to eccentric shaft), you name it! I just found out about it.
There is an ongoing trickle of interest for rotaries for UAVs, potentially light piloted aircraft. They're a much better fit in aircraft than cars. When cruising at constant rpm for hours at a time, a rotary can be more fuel efficient than an equivalent aviation piston engine. More efficiency = more time on station.
Also no cats on airplanes so they can build it properly instead of compromising.
The turbine idea is interesting, maybe in a ducted fan set up of some sort. The rotary is potentially compact enough to fit inside a duct, where a piston engine would look awkward. Especially if its a 3 or 4 rotor with a small frontal area.
Loki, that's been an interest for a long time, like you said fuel economy, but more importantly power to weight ratio which is huge in aviation. The constant problem is reliability, there is no side of the road to pull over 5k feet in the air... You can glide, but only for so long. In aviation, reliability trumps cost/savings.
Loki, that's been an interest for a long time, like you said fuel economy, but more importantly power to weight ratio which is huge in aviation. The constant problem is reliability, there is no side of the road to pull over 5k feet in the air... You can glide, but only for so long. In aviation, reliability trumps cost/savings.
On the other hand, I'd imagine these aviation engines are a lot better maintained and checked than your Average Joe car owner who doesn't even know how to check engine oil level...
Rotary is fairly reliable when properly maintained. If you want to talk about longevity, that might be another story, but given that these aviation engines usually run at constant load and speed, these engines may last longer than road rotary engines.
I mean, if you think about where the whole "RX-8 is unreliable" comes from, it's mostly because of the shitty early ignition coils that don't last long.
Last edited by UnknownJinX; 02-14-2018 at 09:36 PM.
Loki, that's been an interest for a long time, like you said fuel economy, but more importantly power to weight ratio which is huge in aviation. The constant problem is reliability, there is no side of the road to pull over 5k feet in the air... You can glide, but only for so long. In aviation, reliability trumps cost/savings.
Oh I know, I fly. But the rotary concept is not inherently unreliable, especially in a constant load application and with aviation spec service intervals. The implementations specific to automobiles have it unreliable. Fast load variation, emissions restrictions, etc. The Renesis's weak points are largely self-inflicted: hot, constricted exhaust port, complicated intake valving for a wide powerband, underengineered ignition parts, catalytic converter. None of that is necessary if you're flying, and you can believe there will be redundancies. Also if you lose a cylinder on a conventional engine, it's produces 0 power. If you lose compression in 1 rotor for some reason, the thing can keep turning with some productive output. No rods to throw and no timing to screw up.
Also if you lose a cylinder on a conventional engine, it's produces 0 power. If you lose compression in 1 rotor for some reason, the thing can keep turning with some productive output. No rods to throw and no timing to screw up.
On the other hand, I'd imagine these aviation engines are a lot better maintained and checked than your Average Joe car owner who doesn't even know how to check engine oil level...
Rotary is fairly reliable when properly maintained. If you want to talk about longevity, that might be another story, but given that these aviation engines usually run at constant load and speed, these engines may last longer than road rotary engines.
I mean, if you think about where the whole "RX-8 is unreliable" comes from, it's mostly because of the shitty early ignition coils that don't last long.
The failure rate seems WAY too high for maintenance to be the main issue. It's a factor for sure, but it doesn't explain how rarely these engines hold compression as long as a decent piston engine (in street applications).
Good points all round, the problem I think is that they will never be in commercially available planes dues to the high maintenance. While most private pilots are well verse and keep up with the maintenance, piston engines are relatively easier to maintain. All it takes is the one dumbass to not follow the maintenance and try to fake the logbooks to bring a mfg down with a lawsuit. Even jet engines are less complicated and easier to maintain, just a whole lot more expensive due to the mats used, specially the turbine blades. Then again, all it takes is a lead pencil to blow up a jet engine, lol
That opposing 4 rotor thing looks interesting. How would you arrange the intake ports in that case?
Hope to see it operate.
Hey according to the documents, P&W Canada is working on this... I'm looking at their Montreal facility out my window at this very moment. Time for some industrial espionage.
Interesting how the side seals flex against/inside the corner seal to keep a 100% sealing without creating any binding....
I wonder if they've actually built any of these and how they ran. They went right to side ports like an MSP engine, but the ports are strangely shaped compared to Mazda trends (very bulbous and round on the end of the port).
02-14-2018 | 10:13 AM
