Could this be an engine to build ???

[Owen_N]

Some thoughts on generation.
They appear to be both epitrochoids.
the rotor looks like the rolling circle is half the diameter of the main circle, and the "pen" is 1/3 out from its center.
The housing looks to be rolling circle of 1/3 the size, and pen is half way out from the cenre.
As to why one generates the other when running geared to a grank in this fashion, that is "interesting".
I assume there is a generating formula that you could enter inco a cam-cad milling machine thart would cut out these shapes.
Anhy ideas offhand?
I could look on google: " cutting epitrochoids on a cam mill??

 

[Owen_N]

https://www.sciencedirect.com/science/article/abs/pii/S0736584507000944relevant? how to do epitrochoid shapes in CNC
the 2:1 50% version looks similar to the rotor, and also the wankel housing.
3:1 50% looks similar to the housing.
why one generates the other is a mystery??

Google: various epitrochoid shapes, epicycles.
nothing on cutting then on a mill...

https://grabcad.com/tutorials/how-to-design-a-wankel-or-any-other-rotary-enginea cad tutorial..- maybe I should do some cadding???

 

[Steamchick]

Sealing the "chambers" has always been the major difficulty with these rotor engines. Thus the engine size has always been on the larger size, to overcome the length of seal versus displacement. A conventional piston with rings has a much easier sealing-system, and better seal-length to displacement ratio. Which is a major reason why these engines continue to dominate commercially.
I understand the Liquid Piston Engine (a misnomer if ever there was one, as the piston is not liquid!) is being used by US military to power drones, because of its small size, use where pollution can be disregarded by the military, and because of the power to weight ratio being good enough. I don't know what these engines are like for vibration/ balance?
Good luck trying to make one!
K2

 

[Owen_N]

Sealing the "chambers" has always been the major difficulty with these rotor engines. Thus the engine size has always been on the larger size, to overcome the length of seal versus displacement. A conventional piston with rings has a much easier sealing-system, and better seal-length to displacement ratio. Which is a major reason why these engines continue to dominate commercially.
I understand the Liquid Piston Engine (a misnomer if ever there was one, as the piston is not liquid!) is being used by US military to power drones, because of its small size, use where pollution can be disregarded by the military, and because of the power to weight ratio being good enough. I don't know what these engines are like for vibration/ balance?
Good luck trying to make one!
K2

There are a number of small Wankel engines on the market, for RC airplanes. I think OS makes one.
They seem to work quite well despite their small size.
They are also too small for what I want to do, about half or less HP than I want to generate.

I would suppose the LP engine is more fuel-efficient than the Wankel layout, as the firing chamber is smaller and better laid out.

You also tend not to sling oil on the sparkplugs.- rotaries give the plugs a hard time.
the smaller ones are glo engines, which don't foul up- they may be too cool, or melt, though.

The military want their small engines to burn diesel or aviation kerosene, as well.

You would think jet kero would be the favoured fuel for everything. Abrams tanks run it, helicopters, jets,
I suppose diesel truck engines can be made to run on it.??

this requires high pressure direct head injection and really finely atomised fuel.

I didn't see any blurb to this effect on the liquid piston websites and articles, so they may not be up and running in the military drones yet.
You can buy very military-looking Wankels in the UK, I think.
POA.
I was looking at one in the 5 hp range.
It had an odd cooling system, and was a bit heavy.

 

[Weldsol]

Looking at the weight at 15.9 kg (35lbs) against the power 160HP for a single unit plus the units can be coupled inline makes this very interesting plus the fact of the skip firing depending on load etc .
For fuel I think they are looking at Ethanol (reading the bio's for their technical director)

Paul

 

[Steamchick]

Owen, I suggest you write to Liquid Piston, as they will possibly have made something in the size you want, or have rotors or casings to sell..?
You don't know till you ask!
K2

 

[alanganes]

Is it just me or does that company website look like it is largely designed to separate investors from their money to anyone else?

Lots of claims are made about the many huge advantages of this design but give no hint that they have actually built and run one yet. Lots of statements about how much better this is that every other type of engine, but seemingly no actual measurements on a running prototype. There have been so many revolutionary new engine designs touted like this, but rarely do you ever see one progress beyond the "burn a bunch of money stage" and actually go into production.

I may just be too much of a skeptic and I know it's easy sit here on my couch and be a critic. But looking at the list or principles and investors they show on the website, surely they collectively have the money, talent, and resources to make one running (even if imperfect) proof of concept unit.

Am I being too suspicious? Thoughts?

 

[Owen_N]

Looking at the weight at 15.9 kg (35lbs) against the power 160HP for a single unit plus the units can be coupled inline makes this very interesting plus the fact of the skip firing depending on load etc .
For fuel I think they are looking at Ethanol (reading the bio's for their technical director)

Paul

1) I don't think there is a worldwide market for ethanol engines- maybe Brazil??

Diesel, Kerosene and Gasoline are easily synthesised from various feedstocks.
Possibly carbon dioxide capture schemes can make production carbon-neutral, and economic.

Bio-ethanol is expensive to produce, even in bio-reactors.
Test plants show there is a very high maintenance requirement.

2) why should anyone change to this engine? It is a niche item at best.
No major car manufacture would touch it. They are doing well with their own technology.

3) It would possibly be good as a "range extender" drive for a generator, for cars.
If battery technology and charging infrastructure develops as we expect, there will be very little need for range extenders.

4) The main interest could be for military use, to replace Humvee and other truck diesels, and the like with lighter kero-burning
spark ignition engines, and drone engines which are better than Wankels.

It could possibly make a good diesel, with the low load fuel economy that comes with diesels.

5) I have a niche interest in the 60-90cc equivalent range, for low vibration RC model aero engines that can be throttled
down smoothly to half or less of full rpms.

Maybe someone else would want to buy for these reasons, if the price comes in under the radial triple four-strokes, at $1350 USD??

It will be more expensive than an equivalent one or 2 cylinder two-stroke, because of the large gears needed, and the extra sealing bits.

I still don't see how the rotor side seals work.
this is not apparent in any photos or diagrams.

The edge of the rotor outer seems quite thin, with wide open porting space visible from the side.
I will look a bit more closely at the "Visible Combustion" demonstration.

 

[Owen_N]

Is it just me or does that company website look like it is largely designed to separate investors from their money to anyone else?

Lots of claims are made about the many huge advantages of this design but give no hint that they have actually built and run one yet. Lots of statements about how much better this is that every other type of engine, but seemingly no actual measurements on a running prototype. There have been so many revolutionary new engine designs touted like this, but rarely do you ever see one progress beyond the "burn a bunch of money stage" and actually go into production.

I may just be too much of a skeptic and I know it's easy sit here on my couch and be a critic. But looking at the list or principles and investors they show on the website, surely they collectively have the money, talent, and resources to make one running (even if imperfect) proof of concept unit.

Am I being too suspicious? Thoughts?

Is it just me or does that company website look like it is largely designed to separate investors from their money to anyone else?

Lots of claims are made about the many huge advantages of this design but give no hint that they have actually built and run one yet. Lots of statements about how much better this is that every other type of engine, but seemingly no actual measurements on a running prototype. There have been so many revolutionary new engine designs touted like this, but rarely do you ever see one progress beyond the "burn a bunch of money stage" and actually go into production.

I may just be too much of a skeptic and I know it's easy sit here on my couch and be a critic. But looking at the list or principles and investors they show on the website, surely they collectively have the money, talent, and resources to make one running (even if imperfect) proof of concept unit.

Am I being too suspicious? Thoughts?

Is this the original 2-bank toothed rotor design?

I would be suspicious of that, indeed! It simply does not look like a good idea as a concept.

The level of investment needed is that which is required to make a prototype.

You could limit this to maybe $200,000 maximum, if tooling is needed.

Possibly someone could make one that actually ran, poorly, in their garage, for a lot less.

 

[Owen_N]

Owen, I suggest you write to Liquid Piston, as they will possibly have made something in the size you want, or have rotors or casings to sell..?
You don't know till you ask!
K2

They state specifically on their website that they will sell you a prototype of your choice of size for $30,000,
intended for evaluation by other companies.

This is probably how they finance themselves at this stage.

They look like they haven't got to the stage of putting stock on shelves yet.

I did send them an email, and that was their response as well.

I could buy an "old shelf stock" Wankel made by Norton, 8 hp, for $1500, but probably a bit heavy for my use.
they say it is a good swap for an old Sachs unit, last made about 1974.

 

[Joe]

Is it just me or does that company website look like it is largely designed to separate investors from their money to anyone else?

Lots of claims are made about the many huge advantages of this design but give no hint that they have actually built and run one yet. Lots of statements about how much better this is that every other type of engine, but seemingly no actual measurements on a running prototype. There have been so many revolutionary new engine designs touted like this, but rarely do you ever see one progress beyond the "burn a bunch of money stage" and actually go into production.

I may just be too much of a skeptic and I know it's easy sit here on my couch and be a critic. But looking at the list or principles and investors they show on the website, surely they collectively have the money, talent, and resources to make one running (even if imperfect) proof of concept unit.

Am I being too suspicious? Thoughts?

Ding, ding, ding, we have a winner. Glitzy CAD drawings and an opportunity of a lifetime. Step right up.

 

[Richard Hed]

Is it just me or does that company website look like it is largely designed to separate investors from their money to anyone else?

Lots of claims are made about the many huge advantages of this design but give no hint that they have actually built and run one yet. Lots of statements about how much better this is that every other type of engine, but seemingly no actual measurements on a running prototype. There have been so many revolutionary new engine designs touted like this, but rarely do you ever see one progress beyond the "burn a bunch of money stage" and actually go into production.

I may just be too much of a skeptic and I know it's easy sit here on my couch and be a critic. But looking at the list or principles and investors they show on the website, surely they collectively have the money, talent, and resources to make one running (even if imperfect) proof of concept unit.

Am I being too suspicious? Thoughts?

No you are not too suspicious. What you are sa;ying is correct, not just for engines but snake oil too. Have you heard of the 6 cycle engine in which there are four half revs tht are just the same as four of the four cycle engines we are used to but the other two, one injects spray water which mackes a power stroke and cools the engine. Interesting concept, it got nowhere. Also the engine that uses water to keep the engine at a nice cool 300deg where the boiling water is used to push steam pistons for power, the other pistons being regular 4 cycles. Apparently this engine was tried in the early 50s but it could not inject the new water at an approprieat time because of mechanical heat measuring systems. That seem s a bit full of balonehy but maybe. Point is now there are electronic detection systems that could over come that. In a regular 4 cycle engine, a tremendous amount of waste heat goes out the tail pipe and out the radiator. My not so humble opinion, this heat should be harvested.

 

[Owen_N]

I started a new thread under engines-discussion, but I can't find it.
Any ideas?
Is the moderator holding it back? Maybe I didn't save it properly.
I was developing the concept of the liquid-piston engine, how it works, how to go about making it,
and formulas for the rotor and housing shape.

Anyhow, I was looking at the "visible" running liquid piston video on you tube.

That appears to use a moulded rubbery polymer main seal- some kind of moulded PTFE- and very smooth chamber sides.

The open-sided prototype shown had the housing and back wall integrated, and a smooth coating of some kind over the inside of the whole cavity. It seems to depend on very smooth inner walls to make the polymeric seal work.

the chamber walls probably run cool enough that carbon deposits are not an issue.




To emulate this, I can laminate a thin sheet of polished stainless steel to a structural component with a less rigorous finish.

Water jet cutting may be needed to avoid deforming the sheet.
I can send that out, with cad drawings.

Level of polish will need to be more than with standard stainless sheet.

A full moulded polymer seal is a bit high tech, but something can be done with a gapped ptfe o-ring with sufficient bendiness.
I will look for some bendy ptfe rod stock.

An angle-sliced end and a bit of lengthways compressive load may deal with the gap.

Possibly a reason that they don't do this is a tendency for the seal to twist or wind up. and for the end gap to be unstable.
A square bottom slot with a rounded insert will deform the PTFE in place and stop it twisting.
It may need an initial preload to make it take a "set".

Pure PTFE usually comes as a bar or slab, and is quite soft.
blended mix ptfe seals are usually quite hard, with low crush. You can't expand them like a normal o-ring.

 

[Owen_N]

No you are not too suspicious. What you are saying is correct, not just for engines but snake oil too. Have you heard of the 6 cycle engine in which there are four half revs that are just the same as four of the four cycle engines we are used to but the other two, one injects spray water which makes a power stroke and cools the engine. Interesting concept, it got nowhere. Also the engine that uses water to keep the engine at a nice cool 300deg where the boiling water is used to push steam pistons for power, the other pistons being regular 4 cycles. Apparently this engine was tried in the early 50s but it could not inject the new water at an appropriate time because of mechanical heat measuring systems. That seem s a bit full of baloney but maybe. Point is now there are electronic detection systems that could over come that. In a regular 4 cycle engine, a tremendous amount of waste heat goes out the tail pipe and out the radiator. My not so humble opinion, this heat should be harvested.

If you harvest the heat, what do you do with it?

You could use a thermocouple array and generate electricity- good for topping up the battery?

More efficiently, you could have low temperature boiler-turbine-generator array and an electric motor.
Probably rather expensive and bulky.
I wonder how small that could be made?

You still need to reject the same heat energy at a lower temperature, though - condenser radiator with a fan?

It seems to work- we have a smallish power plant running up the road from us, using geothermal waste water.
I think an Israeli firm sells them.
It all sits out in the open, in about a 30 meter square, with sun shades.

 

[Richard Hed]

If you harvest the heat, what do you do with it?

You could use a thermocouple array and generate electricity- good for topping up the battery?

More efficiently, you could have low temperature boiler-turbine-generator array and an electric motor.
Probably rather expensive and bulky.
I wonder how small that could be made?

You still need to reject the same heat energy at a lower temperature, though - condenser radiator with a fan?

It seems to work- we have a smallish power plant running up the road from us, using geothermal waste water.
I think an Israeli firm sells them.
It all sits out in the open, in about a 30 meter square, with sun shades.

notice that the engine temp is 300 deg F. This is very high temp for an ICE. The pressure built up from this is used to power an extra piston on the engine for power strokes directly. If one did not want to do this method, I'm sure theere are other ways to use it. Point is is that the larger part of the energy is wasted.

 

[Steamchick]

I had an enquiry/discussion with a Professor of Engineering at the local university about 15 years ago. (I was there for a CAD train course... as the system had completely changed! - again).
He was looking at a project for a couple of post-graduates who were studying how to improve efficiency of fuel-cells.... by waste heat recovery. Necessary to get them above the ficiency of a constant speed turbo diesel ICE and generator..... His idea was a boiler in the exhaust (from the fuel cells!) to power a conventional steam turbine and generator. But the numbers would not add up to a "useful" (cost effective and fuel efficient) answer....

His initial idea was that a conventional Hybrid used a ICE with sufficient power for 70 mph cruising, plus batteries and electric motor to give improved acceleration. Traction Batteries were recharged by Brake power recovery, and waste heat recovery, and the IC engine when spare power can be utilised and is needed for recharging. But then he tried re-working with a fuel cell.... of similar power to replace the ICE. Of course, if this was commercially practical we would have them on the road by now....

K2

 

[Richard Hed]

I had an enquiry/discussion with a Professor of Engineering at the local university about 15 years ago. (I was there for a CAD train course... as the system had completely changed! - again).
He was looking at a project for a couple of post-graduates who were studying how to improve efficiency of fuel-cells.... by waste heat recovery. Necessary to get them above the efficiency of a constant speed turbo diesel ICE and generator..... His idea was a boiler in the exhaust (from the fuel cells!) to power a conventional steam turbine and generator. But the numbers would not add up to a "useful" (cost effective and fuel efficient) answer....
K2

How do these particular cells work?

 

[Steamchick]

You blow hydrogen and air into the matrix of chemical coated conducting plates, and the electrons from the hydrogen land on one plate, run around an electric circuit to the other plate to combine with the oxygen in the air and produce steam (chemical water in a gasious state) at low pressure and high temperature. This is the exhaust. The electrons supply electrical power in the process. Used mostly on spacecraft!
K2

 

[Richard Hed]

You blow hydrogen and air into the matrix of chemical coated conducting plates, and the electrons from the hydrogen land on one plate, run around an electric circuit to the other plate to combine with the oxygen in the air and produce steam (chemical water in a gasious state) at low pressure and high temperature. This is the exhaust. The electrons supply electrical power in the process. Used mostly on spacecraft!
K2

Ah, I see. How large is this cell, how many watts? What temp is the exhaust? There has to be a point somewhere in which the exhaust will have enough bang to be useful.

 

[Joe]

I have been a big fan of the Wankel rotary engine now for half my life. I have owned and driven a couple of Mazda RX7s and plan on cutting a 13B I have, in half to put in my late 70's Suzuki truck. For probably 2 decades I was on a fabulous news group dedicated to the development of rotary engines for use in aircraft. There are a lot of myths out there about the rotary. Initially there were problems getting the rotor apex seals to last an acceptable length of time but Mazda spent millions on the problem and solved the issues in the early seventies. But the myth lives on. A rotary will indeed run without seals but you won't realistically be able start it without them. If a rotary sits for an extended period an apex seal can stick making for a hard or non start, but it's easily dealt with by removing a couple of spark, squirting in a little transmission fluid and poking the apex seal.
A few of the main attractions of the Wankel for aircraft use are small size, power to weight ratio, high duty cycle, high power potential, stackability, incredibly smooth operation, very low parts count, no reciprocating forces and no valves. The time to climb record from a standing start to 15000' is held by a modified Mazda based rotary. One of the biggest hurdles to a successful implementation is the cooling system, it's not difficult but it has to be done correctly.
Just after the second war, aircraft engine builders looked at improving their large radial engines. Wright led the pack and went after the heat and pressure coming out the exhausts which is by far the greatest point of waste energy. They incorporated blow down turbines into this energy stream, 4 per engine I believe and they recovered 1200 hp if my memory serves me correctly. They used these engines in several military applications and on the Constellations which basically made the Atlantic a viable opportunity. The Achilles heel of this engine was, as with most aircraft engines the exhaust valve. It was a very common occurrence to arrive on the other side of the pond with at least one engine shut down. Then came jets. Of course the Wankel doesn't have valves.
Chevrolet, Ford, John Deere, Rolls Royce amongst others have all made Wankels and Rotax, Norton, OMC, Suzuki, Sachs, NSU have all had production models and of course Mazda has produced millions. If Mazda had mastered the Wankel at the same time that Otto developed the four stroke ICE then we would all, without a doubt, be driving rotary engines and scoffing at the idea of building reciprocating engines.