rotary outboard anyone?

Not a lot of use when you need the prop shaft to turn at less than 2000rpm and the output shaft on this motor turns at 10-15000. Just imagine the size of the reduction box and the losses involved in stepping down.
 
Tranona said:
Love the distorted size comparison with an ancient "standard" diesel - which is at least twice the bulk of a modern 35hp diesel.
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Point taken but even so.....

Is the high rpm part and parcel of the design/configuration do you think.
Would it be possible to design a low rpm version. (asked as a non engineer)
 
mudkipper said:
Is the high rpm part and parcel of the design/configuration do you think.
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Yes. It rotates rather than reciprocates and has no reciprocating valves. This means it can rev higher with lower stress on components. Gas turbine engines like helicopter turbo-shafts rotate at a very high speed in comparison to piston engines but are completely in balance, so they get away with it.

mudkipper said:
Would it be possible to design a low rpm version. (asked as a non engineer)
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Yes, but it would need to be bigger to achieve the same power because power is torque x rotation speed. Increasing torque but keeping the size the same is not going to happen much unless some kind of forced charging is used, and that will increase price, weight, size, complexity.
 
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mudkipper said:
Point taken but even so.....

Is the high rpm part and parcel of the design/configuration do you think.
Would it be possible to design a low rpm version. (asked as a non engineer)
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I would guess that the high RPM is possible due to the lack of reciprocating parts & increasing RPM is a simple way of increasing output. High revving small motorbikes have had small strong gearboxes for years, I don't see it doing more than doubling the engine size. Or I suppose one could use a small high revving prop like speed boats do, or even a mix of both. It's an interesting idea - looking at the cut-away cycle, would you call it a 3 stroke?
 
AngusMcDoon said:
Yes. It rotates rather than reciprocates and has no reciprocating valves. This means it can rev higher with lower stress on components. Gas turbine engines like helicopter turbo-shafts rotate at a very high speed in comparison to piston engines but are completely in balance, so they get away with it.



Yes, but it would need to be bigger to achieve the same power because power is torque x rotation speed. Increasing torque but keeping the size the same is not going to happen much unless some kind of charging is used, and that will increase price, weight, size, complexity, cost.
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Thank you for that
 
This sounds interesting ..
"It also uses fixed seals installed in the housing, rather than installed on the rotor"

Would have thought that if that's possible and I can't see how, Mazda would have done it.
 
Don't hold your breath waiting for this engine to appear. I am old enough to remember when the Wankel engine was the latest thing, and how it was going to revolutionise everything that needed an engine. I'm still waiting.
 
As Norman-E says, we've been waiting for the Wankel for a long time! But supposing they've cracked the sealing problem and the seals last a reasonable time and the gearbox could all be made to a reasonable cost, it's still almost certainly inappropriate for an outboard because outboards do not run most of the time at full revs, which is where the Wankel wins.

However it could be good as the power unit in an air-cooled generator since it would be much, much quieter than those horrid little petrol generators which proliferate today. And it could be much lighter and quieter than any diesel one currently available. The very high engine speed need not be a disadvantage for electric power generation (rectify the high frequency multi-phase output and then invert to mains Volatge and frequency).

Post script: I suppose one could make a diesel-electric outboard, but that's getting a tad silly I think.
 
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On a Wankel engine the seals are between the tips of the rotor and the walls of the chamber so they must be attached to the rotor. On the Liquid Piston engine the seals are at three fixed points in the casing, making contact with the smooth edge of the rotor as it moves past. However, they will still need lubrication and that oil will be lost so I am not convinced that they will save much. The problem that is often overlooked with Wankel engines if that you also have to seal the gap between the ends on the rotor and the chamber. Similar seals will be needed for the new engine too.
 
charles_reed said:
It will probably lose about 15% of the power and weigh more than the engine.
As no one is actually manufacturing it, I'd suggest the whole thing is even more speculative than a concept car.
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3% in a decent single stage planetary box and 5:1 would be fine.

Gas turbines like the PT6 use a planetaery reduction box to get useable shaft speeds out.
 
well if we remain in the EU I suspect they will carry on and on cracking down on emissions to the point where we can only buy a Torqeedo...unless someone can run an engine on poo with no emissions!
 
I assume it would be a good unit to attach to a dynamo - they like running at high revs - it also says it is quiet - which would be a blessing

as for panetary gears - creation of god

derailer - work of the devil

D
 
dylanwinter said:
I assume it would be a good unit to attach to a dynamo - they like running at high revs - it also says it is quiet - which would be a blessing

as for panetary gears - creation of god

derailer - work of the devil

D
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Nowt wrong with derrailleurs unless you bend them, or fail to adfjust them properly. Read the Park Tools web site for instructions on setting them up so that they work first time & all the time.
 
Every so often some optimistic dreamer comes along with a modified Wankel engine which will produce lots of power, quietly, from minimal quantities of any fuel you care to throw at it. None of these inventions every gets anywhere, most because - as in this case, as far as I can see - they haven't actually built one yet.
 
JumbleDuck said:
Every so often some optimistic dreamer comes along with a modified Wankel engine which will produce lots of power, quietly, from minimal quantities of any fuel you care to throw at it. None of these inventions every gets anywhere, most because - as in this case, as far as I can see - they haven't actually built one yet.
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The video shows it running. Is that just a computer simulation then? Bloody good one if it is. :p
 
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