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Concept: Modified Rotary Engine with Integral Flywheel Effect

A cutaway sketch of the RIDE engine in combustion mode. Note the offset of the crankshaft from central rotational axis.

A Virginia inventor is devising a rotary engine with an integral flywheel effect to serve as a single-unit hybrid power plant. Gary Greenwell’s new RIDE (Rotational Inertial Dampening Engine) modifies the design of the Gnome rotary aircraft engine design of the WW I era to enable the rotating engine block to function as a freely-spinning flywheel, thereby offering an integrated flywheel-based hybrid power capability.

Greenwell (who has 30+ years in the engine side of the auto industry) estimates that the RIDE engine, through its combination of combustion power and kinetic energy storage, could support automotive fuel economies in the range of 100 to 120 mpg without the additional cost of electric motors and batteries.

A cutaway drawing of the Gnome rotary engine. The inlet valve was in the piston.

The Gnome. The Gnome radial engine—developed almost a century ago—seems counter-intuitive. It features a crankshaft mounted on the airplane, with the rotary engine block and cylinder heads—to which the propeller was attached—rotating around the crankshaft. In other words, the propeller and engine block rotated as a unitary segment.

A number of early aviation engines were designed in this manner. With the crankcase and cylinders revolving in one circle, and the pistons in another, offset circle, there were no reciprocating parts and no need for a heavy counterbalance. The momentum of the crankcase and cylinders smoothed out the power pulses, thereby eliminating the need for a heavy flywheel. These rotary engines had the best power-to-weight ratio of any configuration at the time.

They also had a number of downsides, notably their total-loss oil systems. Centrifugal force threw the lubricating oil out after the first trip through the engine. The aircraft’s range was thus limited by the amount of oil it could carry as well as fuel. A gyroscopic effect created by the spinning mass also made maneuvering the airplane difficult—not a good feature in a fighter aircraft.

RIDE as a rotary engine. Greenwell made a number of significant changes to the rotary design, including inverting the relationship between the cylinder heads and the pistons. Rather than have the cylinder heads rotate as part of the radial engine block, Greenwell has the pistons affixed to the exterior ring, with the cylinder heads attached to the crankshaft.

There are no connecting rods as in the Gnome, and no valves in either the piston or the cylinder head. Instead, the rotation of the cylinder ring uncovers inlet and exhaust ports.

Moving the cylinder heads close to the fixed center where the ports would be located allowed the elimination of valve train components. The inversion also addressed the issue of centrifugal forces that cause the lubricating oil to migrate into the cylinders (as in the Gnome).

Reversing the position causes the oil to migrate away from the combustion chambers, thereby reducing the need for fine-tuning the piston rings for oil control, according to Greenwell.

Avoiding the total oil loss system entirely, RIDE will use a lubrication system more similar to the dry sump systems used on aircraft engines. Pressurized oil would be supplied to the center of the engine, to be centrifugally distributed to the outer perimeter, where small return pumps would force it back to the center.

Although it can be applied as a spark ignition system, RIDE is ideally a compression ignition system.

The key invention, though, is the Powerswitch: the moveable crank journal that allows the engine to convert to flywheel mode, along with its management software.

RIDE as flywheel. While the rotary combustion engine capability of RIDE might be mildly interesting, it is its ability to convert to flywheel mode for energy recovery that is the unique aspect of this approach.

RIDE switching to flywheel mode. Note the movement of the crankshaft from being offset in combustion mode to aligned on the central rotational axis in flywheel mode.

RIDE makes the crankshaft a separate part from the engine support bearings. This change is critical to the revised radial design, as it allows the crankshaft to move to be positioned exactly as the rotational axis of the moving engine block—which, in turn, changes the running engine to a freely-spinning flywheel.

The pistons go from relative reciprocation to stationery in their cylinders when the engine is in flywheel mode. The switching mechanism—Powerswitch—is one of the key inventions for which Greenwell filed a patent in 2004.

The flywheel can store power for short periods of time, as well as recover energy from regenerative braking. (AFS Trinity was earlier exploring the viability of a flywheel-based hybrid drivetrain before opting for a more conventional battery/ultracapacitor approach it has under development with Ricardo. Earlier post.)

The RIDE engine will constantly transfer from fuel power to stored energy, while the vehicle speed remains constant, with the CVT (continuous variable transmission) adding power to the vehicle power train in the exact amounts necessary to compensate for all losses regardless of their origin.

This engine design recovers the vast majority of braking losses by converting linear inertia (vehicle) into rotational inertia (engine) in an exchange that involves no additional components than a currently produced vehicle.

This energy storage capability, Greenwell argues, will eliminate the vast majority of idling losses (100% losses). Utilizing the appropriate variable transmission and computer controls, regenerative braking can recover most of deceleration forces.

(Dynamometer figures, Greenwell notes, demonstrate that a reciprocating engine running at 2,000 rpm uses half the fuel consumed, to merely maintain that speed with no force applied to the drive wheels: “the penalty of reciprocation,” as he calls it.)

This is a large part of the function of hybrid designs—to replace combustion when it is least fuel-efficient (idling, stop-and-go driving, etc.) with a different, more efficient source of power and to recoup the kinetic energy from braking or deceleration—but hybrids require the addition of the additional power and energy storage systems (e.g., electric motor and battery pack).

The basic concept can be best understood in this example. You are stopping from 40 mph, and the linear inertia of the vehicle is converted to rotational inertia in the engine-flywheel, to be reapplied for acceleration when it is required.

If the system was capable of 90% efficiency re-acceleration would get your vehicle to 36 mph from the recovered energy. During the whole period of time this is occuring there would be no fuel consumed.

The flywheel storage would provide the power to accelerate, and after 36 mph you would need to run the engine (consume fuel) to restore flywheel inertia. The flywheel would never stop spinning while the vehicle was in operation, the fuel burning run mode [also] serves the purpose of restoring the flywheel’s inertia when it is depleted.

—Gary Greenwell

RIDE, according to Greenwell, is capable of storing 4 times the force in regeneration that it can produce by combustion.

Applications. As initially envisioned, the RIDE engine is purely a combustion engine. However, its design optionally includes auxiliary energy storage in other forms, such as compressed air or electrical. It could also function as the motor/pump in a hydraulic drive system.

RIDE is a subsidiary of EDGE Office Solutions.




Brilliant. Simply brilliant.

Simple construction, no harsh vibrations from compression ignition (the cylindars fire one at a time I believe), regenerative braking, great power to weight ratio.

I think that this is the engine of the future. Doesn't matter if we run gasoline, disel, ethanol, or hydrogen. This is it.

Roger Pham

Interesting idea. But can any genius out there tell me how in the heck that this guy can claim fuel efficiency in the 120 mpg range? In what vehicle. Sure, if you put a Honda lawnmower engine in a ultra micro car under 1000lb weight, you too, can achieve 100 mpg plus!! I don't see any combustion advantage or thermal advantage of this engine over existing engine.
1) Engine cooling: liquid cooling seems out of the question, meaning engine reliability will suffer.
2) For Compressed Ignition cycle, how do you put thousand-psi fuel injectors on the cylinder heads when all the cylinder heads are spinning like crazy, without fuel leakage between the central fuel pipe to the spinning fuel distributing spokes radiating from the center? Because the cylinder heads are off-center during engine operation, the fuel spokes must be of the telescopic type, hence much greater potential for fuel leakage at the thousand-psi range. So, diesel operation is probably out in this contraption. Overhead poppet valve operation is out of the question. This leaves one with two-cycle operation, with all of its inherent disadvantage that even many lawnmowers and motorbikes now a day advance to four-stroke cycle operation, far cleaner and more fuel-efficient.
3) For engine rotation in the few thousand rpm's, the engine mass is not sufficient to support any meaningful energy storage. Meaningful flywheel storage has rpm in the tens or hundred thousands rpm's, and even then, the energy contained is small in comparison to a battery (NiMh) of the same overall weight.
Good Luck!!


I should think it could be improved even further by replacing the center crankshaft with a simple pivot bearing, then putting a cam profile on the outer ring to provide the compression needed for diesel operation. Maybe rollers on the piston ends too.

For gasoline operation a spark plug could be mounted recessed in the piston with the conduction of HV going thru the roller to a HV spot in the cam profile.

This way you still get the benefits of having rotating mass (except for the outside ring) and reduce the bearing problems with the crankshaft.



Let's start a wager: who many days can we go before a new engine is announced on GCC?

Sid Hoffman

My thoughts exactly, dursun. This is much like the dot-com boom of the late 1990's. Fuel economy and hybridization is the hot new thing and all these companies are promising riches to anyone that will dump a load of venture capital on them. Of course, they'll use that capital to first, give themselves a huge salary and bonus, and second, build an unmarketable prototype engine that will never do anything to produce a ROI for the venture capital.

hampden wireless

If this engine could be built for the price of a comparable power regular engine it would be great. The flywheel part would help city driving but not as much as a full hybrid system in all cases. It looks like it could store ONE round of energy from breaking. It might be able to store that one round more efficiently then an electrical hybrid but down a long hill or up one it will run out of storage capacity quickly.

This could be a great engine.

Harvey D.

more of the same!!!


Wake me up when this stuff actually comes to market. I admire the innovaters and inventors though. Besides Exxon Mobil will buy the patent out to quash it. By the way any of you seen the misleading ads on youtube and soon in many states which states that global warming is a myth? It is sponsored by the American free enterprise institute some libertarian outfit. Guess who paid for the ads? Yep you got it, Exxon Mobil. Scum!

Barry R. Guthrie

I might not completely understand this concept, but I think this has the same downfall of the WWI engines in that the engine has a large rotating engine mass that generates large centrifugal forces that result in high stress and wear.

How is the engine lubricated?


Using a modified WW1 fighter engine in a car? Seriously cant figure out why it could reach 120 MPG.


Back in the 70's during the first and second oil crisis, Popular Science would have a "new " engine design on the front cover every other month. Other than the Wankle we never saw them again..until now. If you want to do an interesting project, go to the library and look at back issues of Popular Science and Popular Mechanics from 1973 to 1978. I don't remember a design from that era like this one, but there are many others. I don't see basic engine design affecting efficiency as much as the development of electronic controls to manage fuel metering.

Tony Chilling

We are in the 21th Century. We should not continue to pursue inventions which don't enhance our continued existence.
One million years from now, when space aliens finally visit our planet, do you want the record of our existence
to be only a thin, Black line in the earth's strata?
I would much rather have human beings greet them.
Sadly, I think we will be only be a thin, Black line.

Shaun Williams

Thank-you Tony C. That was a definate LOL moment for me, nicely put.

Gary Grenwell

The claim of 125 MPG is based on the application tactic. Consider the fact that this engine when running is not paying the energy penalty of reciprocation, which amounts to about 50 % of consumption (sustained speed dyno tests, not real world situations where the difference would be greater). If you consider the 1984 Honda CRX HF (70MPG highway) as an example and you eliminate the 50% reciprocation cost, I consider the mileage claims to be conservative. Factor in aerodynamic improvements, the CRX had a CD of .39 while the Prius is in the mid to high 20S, and the claim becomes more conservative, not even including the low percentage of time where regeneration will occur.
It has been known for decades that the basic automobile's efficiency can be greatly enhanced by the operational tactic of accelerating the vehicle, then shutting down the engine and allowing the linear inertia of the vehicle to be maximised, by coasting. The downside has always been the constant changing speed of the vehicle, which constitutes and unacceptable sacrifice, in real world driving.
Rotational Inertial Dampening Engine reflects the ability to maintain a constant vehicle velocity, while the engine restores the energy drains by "running" and consuming fuel, to increase the flywheels speed and level of stored energy. The energy restoration cycle will only occur at a small percentage of the total time the vehicle is in operation, the estimate is 25% or less at sustained highway speeds.
The issue of sustained hill climbing ability is adressed by simply sizing the engine to produce sustained power for severe application parameters. It is crucial to understand that when reciprocation is eliminated, the displacement of the engine becomes a non issue. The larger engine will be capable of sustained high loads (hill climbing) and will simply store more flywheel energy with fewer combustion cycles, with the total energy cost remaining constant.
As far as valves, spark plugs, fuel delivery, cooling, and other questions inherent in the design, there are solutions. Lets just say this, the originals were reliable, capable of surviving battle damage, and in fact some are still operational in a small number of cases even when the engine is 88 years old.
Torque was a dangerous factor in the original aircraft applications. In a vehicle application torque is your friend, exactly what you need to climb steep grades. This engine is a torque monster.
Assume for a minute the total "run" time is less than 20% overall, that means you are not generating waste heat during 80% of this same same period of time, which will greatly reduce cooling requirements in the first place.
By increasing the oil supply, and using the "dry sump" principle of a closed loop lubrication system, you can remove the (much lower) heat losses. There is also the potential of using air flow through the engine without combustion to provide additional cooling (direct in cylinder cooling). The returned oil can be thermostatically diverted through a separate oil cooler, so excess high load heat can be removed when necessary. Remember when the 65% heat losses of conventional engines are converted into mechanical energy, the cooling systems capacity is reduced in direct proportion to the reduction is wasted heat.
This engine will deliver a constant volume of fuel for each combustion stroke, using compression ignition, the amount of air can be greater than the ability of the fuel to burn that air completely, testing will determine the ideal ratio, when a prototype can be dyno tuned to maximise the benefit. Excess air in the combustion chamber will also serve to reduce peak temperatures and allow heat saturation of the unburned oxygen in the excess air.
This is a new machine, not just an engine, my approach was more systematic than focusing on the engine only.
When configured in a 4 cylinder application, with the purpose of creating an Infinitely Variable Transmission. You have a very simple machine that will provide fluid pressure. As the "stroke" is increased from 0 (no fluid transfer) you have a high pressure-low volume flow, that progresses to a low pressure high volume flow. You can have a low gear ratio of 1000 to 1, and progress to a ratio of 1 to 1000. This pressure can be routed to another "pump-motor" in the wheel of the vehicle, eliminating all of the powertrain components necessary in a conventional application. The result is a 25% reduction in the total number of individual components per vehicle, just the opposite of conventional hybrid designs, no $8000 batttery, or $6000 electric motor, which makes a current hybrid a throw away car at 100,000 miles when the warrantee runs out.
There are no "black holes" or real trade offs other than the process of development. It has always been necessary to look at the vehicle in a systematic method when developing real improvements. The piston in cylinder configuration was and still is the only advantage of conventional reciprocating designs. You dont have the swept area issues of other rotary engines, that will always be an issue as well as the sealing problems when you try any other combustion chamber configuration.
Another advantage of the original aircraft rotary design is the "centrifugal supercharger effect". I intend to incorporate this into forced induction with no necessity for any increase in the per engine parts count.
Consider the current 4 wheel drive compact pickup truck dedicates almost 50% of its weight to powertrain components. This concept has the ability to provide completely independent 4 wheel drive, switchable to 2 wheel drive at any speed, while retaining 4 wheel regeneration capabilities. All of this is not even in the conceptual stage in current vehicles.
Sure flywheels are not as efficient at lower speeds. The other side of the coin is understanding the fact that flywheel storage in a vehicle does not have to be for an extended period of time. A 300 pound mass spinning at 9000 RPM (max regeneration speed without combustion- max combustion speed is 4000 projected)is capalbe of storing a considerable number of horsepower-seconds of recoverable energy, and that storage does not need to be for periods of time longer than a couple of minutes. The whole engine can be built using a lathe and a vertical milling machine.

thanks for you imput


Tony Chilling

First, Thank you for your time visiting this forum.

1)When will you have a working unit?

2)If the fly wheel effect helps fuel economy, why don't normal hybrids have them, even just a less massive unit?

3) ("pump-motor",) why isn't Hydraulic power transfer, to the wheels, used today in cars?


Gary. I advocate for Plug-in Hybrid technology because of the advantages inherent with electric motor and battery storage. They should not be eliminated. The rooftop photovoltiac industry has met its match. Such a homepower system will be invaluable in an emergency, will lead to public power, will offer an education in household electricity conservation. Carefully placed batteries lowers vehicle center-of-gravity, improving handling and stability, a safety feature especially applicable to top-heavy SUVs. A hybrid engine may burn any fuel and perfect its combustion via strict regulation of engine speed and load.

And the big topper: a car that drives a limited range on battery power alone creates an economic incentive to drive less, patronize local economies, develop destinations accessible without having to drive. Ultimately, walking, bicycling and mass transit, (more economical means of travel), become the viable travel options they are naturally meant to be.

If your engine has some application that can top these advantages, or compliment them in some way, I'm all for it. But, please consider what the real problem is: we drive too much, too far, for too many purposes, at too high cost and impact. The Plug-in Hybrid is the only technology I've found that has the potential to actually reduce dependency upon long-distance travel.

The challenge of the 21st Century is not to build a better car. The challenge is to build a better city.

What's the nickname of the George Washington Bridge?

The car-strangled spanner.

Roger Pham

Ah, Hi, Mr. Greenwell, the original inventor. How good to have your most informative reply.
1) Regarding your claim that reciprocating motion cost 50% of piston engine's efficiency: I DON'T THINK SO. In a piston engine, the downward power stroke of the engine transfers kinetic energy into accelerating the flywheel, which will in turn power the rest of the non-powering strokes of the 4-stroke cycle. Reciprocating action of the piston does not waste energy nor power to any appreciating extend, providing that a flywheel is provided to absorb the energy. You don't believe this? Just look at the Wankel rotary engine. This engine has none of the reciprocating action of a piston engine, yet it is 20-30% less efficient than piston engine, most of this reduced efficiency is attributed to poor combustion process causing of more unburned or partially burned fuel in the exhaust. The lack of reciprocating action DOES NOTHING improve the efficiency of the Wankel rotary engine.

2) You haven't answer how you are gonna provide thousand-psi-level fuel injectors for this compress-ignition engine. Nor have you answer how to provide for poppet valve action in order to make it a 4-stroke cycle gasoline engine. As such, you'll have to resort to 2-stroke-cycle operation, with all associated disadvantages.

3) If you can't make your engine to run in efficient low-exhaust-emission, compress-ignition mode or 4-stroke-cycle mode, then the advantage of your engine in being able to run at optimum speed for 20% of the time and shut down and coasting for 80% of the time using flywheel-action will be a moot point.

Any auto manufacturer can simulate the action of your engine by using a conventional auto engine and a similar CVT connected to a significant flywheel capable of much higher rpm than your engine, hence reducing the weight of the flywheel significantly. (remember that E=1/2M(V-squared)) Using a CVT connected to a flywheel to increase the speed of the flywheel from 2000 rpm as in your engine, to 10,000 rpm will be able to store the same kinetic energy as your engine at 1/25 the weight of the rotational mass of your engine, hence making the additional weight of the flywheel negligible. The flywheel can be made even lighter than 1/25th the rotational mass of your engine if nearly all of its mass will be concentrated at the periphery of the flywheel, which is the way all flywheels are made. The entire advantage of your engine can be simulated by this last paragraph without none of the unproven concept or hardware associated with your engine concept. The low energy stored in your engine flywheel action means that the engine must be constantly turned on and off, and the CVT must constantly be adjusting its ratio, hence will greatly increase the wear and tear rate of your engine and transmission.
Of course, Toyota has evaluated this along with hundreds of other energy-storage hybrid schemes, and found that this flywheel concept would still be inferior to their gasoline-electric Atkinson-cycle hybrid layout, hence that's what we see in the market place today, gasoline-electric hybrid, the precursor to the long-anticipated plugged-in hybrid that will promise to liberate us from petroleum dependency.

Your follow-up comment will be greatly appreciated.


Pie-in-the-sky ideas for "improving" the efficiency of automobile engines pop up every day. What's funny is that most of them (like this one) focus on changes to the method of making pistons move within cylinders. They do nothing to improve the basic thermodynamic efficiency.

Where do you get "the 50% reciprocation cost"? There's no such thing. While there's a fair amount of friction between the moving parts in a standard piston engine, the rotary design does nothing to address that.

What's not-so-funny is that a Green Car Congress would waste our time on this nonsense. I refer to it often for information about real alternate energy progress. It's a shame that GCC can't focus on real news.

Gary Greenwell

The wankel is not a true rotary engine, if it was a single rotor would be all thats necessary. Swept area heat dissipation as well as the impracticallity of trying to seal the combustion chambers with reliability are unresolveable issues. To use it in a comparison to this engine has no true revelance, they are completely different in every way. I owned a RX2 in 1973, the engine disintegrated at 12,000 miles, the dealer replaced it for free, it got 12 miles per gallon in a 2000 pound car. The current RX8 gets in the low 20s on the highway, great for performance, atrocious for economy.

My Scion XB at 68 MPH is running at 3000 RPM, and consuming 2 gallons of fuel per hour (34 MPG). At 3000 RPM the pistons, and a certain amount of the mass of the connecting rods is reciprocating. Each piston (and piston pin) must start at TDC and accelerate to 90 degrees, then decelerate to 180 degrees, accelerate to 270 degrees, and decelerate to 360 degrees, undisputable fact.

At 3000 RPM that equates to 50 RPSecond.
Thats 4 acceleration and deceleration cylcles, four pistons, 50 times a second, for a total of 800 oscillations PER SECOND. Are you claiming that has no energy cost, again against the laws of physics. Test this on a dyno, fuel consumption rates at loads of 20 lbs torque, then 40, and 50 (pick your best engine). When you look at the results on graph or run the dyno with no load, the engine still uses 50% of the fuel consumed at the 50 lb torque setting. My engine could rotate at 3000 RPM for an hour, while consuming fuel to compensate for losses less than 1 minute in that same hour. Thats a ratio of 60 to 1 and it could easily be 120 to 1, where your engine is running and mine is not. A toy gyroscope demonstrates this clearly.

The flywheel in your engine is there to dampen vibrations, it has no effect on the forces generated by this reciprocation other than to dampen the inherent vibrational chaos in violating Newtons laws of inertia. You need rubber engine mounts to further dampen the vibrations, and you need to run the engine when no real work is being done, at least 700 RPM, to overcome the cost of reciprocation, and even more vibration. I have seen race cars with lightened flywheels where the gears in the transmission rattled at speeds below 1500 RPM,in neutral, due to the lesser weight of the flywheel. Bottom line is the addition of a flywheel in a conventional engine does not allow you to violate the laws of physics. Without a flywheel, your car would be undriveable, and would soon shake to pieces. The weight of your flywheel is an impediment to performance, ask any race car mechanic. Oh and also remember the crankshaft counterwieghts, harmonic balancer, all for the sake of dampening vibration due to reciprocation. They even had to put balance shafts in 4 cylinder engines above 2.4 liter displacement to further dampen vibration. Do I need to keep going? How many bandaids does your engine really need? None are necessary with my design.

The question here is how much fuel does the Scion consume just to keep the engine running at 3000 RPM, with the vehicle stationary in neutral. Dont try it on your car, since the fuel rail absorbs heat that returns fuel to the gas tank, running the engine like that causes the fuel temperature in the tank to climb fairly quickly, so accurate measurements are almost impossible.

The original aircraft rotary engine was a miracle in its time. I am aware of no other piston in cylinder engine design that eliminates reciprocation. The originals were capable of 200 HP, at 1300 RPM, with a displacement of 750 cubic inches, and a weight of under 400 lbs, on fuel of such poor quality your car wouldnt even idle using it today. The Mercedes 200 HP grand prix engine of the same era had a displacement of 1400 cubic inches and ran at almost twice the speed of the aircraft rotary. The original rotaries were very expensive to build, and the engine cost more than the rest of the aircraft. Each cylinder was machined from a 96 pound nickel steel ingot to a finished weight of 6.5 pounds, an exorbitantly expensive and time consuming labor investment. During war cost was no object, after the war it became the only consideration, and combined with the castor oil vapor bath the original design withered on the vine. Today a CAD design and computerised milling as well as investment casting could pop them out lik rabbits, and they dont need cooling fins machined individually. Check the name Stephen Marius Balzer, look at the car he donated to the Smithsonian in 1899.

On the topic of emissions, since the basic design is still a piston in cylinder, all of the current emeissions technology is still viable. The logistics of application will require some work. A good counterpoint to this concern is to consider this.

Assume my calculations about unloaded running are correct, your engine is creating heat, while doing nothing (idling in a traffic jam). When you accelerate, you have more work to do to overcome the cost of reciprocation (at least 50% of the fuel consumed). When you are at aconstant speed that percentage is between 50% and 100% depending on the load you are applying to the engine. When you are decelerating a part of that deceleration is drag from your engine, to prove this put the car in neutral, compare the distance travelled to the distance if you just leave it in gear and let completely off the gas.

As far as a combination of conventional engine and separate flywheel, with a hydraulic IVT powertrain, that certainly is feasible. Check the 21st century roadmap on the web. You will see various configurations that describe you suggested application, and it is viable. The main problems are your engine needs to completely start and stop each cycle, while my design does not. Your application also uses a power source that is much less efficient than mine, you can argue the percentage difference, I will stick with my 50% figure.

All of this information is confirmable, if that is necessary. Several thousand hours of work here on this design, with a 40 year infatuation for automobils behind every statement.


Yes energy is required to accelerate the piston on each stroke. However, that energy is returned to the crankshaft when the piston decelerates. There's no net energy requirement to make a piston reciprocate except for the frictional loses between the parts.

Barry R. Guthrie

I still don't know how your are going to lubricate the system and not contaminate the exhaust with the lubricant emissions?

I also don't know how you are going to capture the exhaust from all the different cylinders and route it away?

Forget about the flywheel issues. You have very large rotating piston cylinders that have treamendous amounts of centrifugal mass that will put great stress on your bearing control system. The mass will have to be great to achieve the high compression ration of 17:1 This added mass may also give you inertia trouble in transient operation with stop and start benefits. It it not so easy to stop and start this large rotating mass. You are going to burn much more fuel in these conditions.

Fuel induction is also a big problem without knock. If you have a center driveshaft induction that goes outward into the rotating cyclinders. This will be virtually impossible. You have gas vapor that will be underneath some pistons that are at TDC and igniting. The heat transfer through the piston will ignite any fuel vapor that is underneath the piston and in the center driveshaft area.

I don't see where you can overcome these problems and achieve the reliablity and durablity you need to be successful over current engine technologies.

Gary Greenwell

Actually initial start and stop occurs only once during each driving cycle. The journal position changes while the engine is spinning at any speed, depending on throttle demands.

Starting this engine consists of initiation of rotation in the flywheel mode. In a pure flywheel weighing 300 pounds you could get it moving with one hand. This engine functions the same way as a pure flywheel. A conventional starter motor would be more than sufficient for bringing the flywheels speed up to 100 RPM. Then you activate the stroke position, and the engine starts running. We could get a wheel and tire spinning to 100 MPH with a small air powered cut off wheel type grinder. That same grinder did not have enough initial power to spin the cutoff wheel in your hand if you held it tightly.

You are not stopping and starting the mass during vehicle operation, you are adding and removing the stored inertia, and converting it to linear inertia bidirectionally in the vehicle, this is the most basic advantage of this system.

Kevin the "pie in the sky" quote makes your position clear. The acceleration and deceleration of the reciprocating masses is a known source of losses. Newtons law applies to acceleration and deceleration equally, and without exception. You reference to the crankshaft returning energy to the piston, contradicts the flow of power from the crankshaft to the transmission and from there to the rest of the powertrain. Even if your statement was valid, you cant have it both ways, any power from the crankshaft to the piston certainly can not be power to the drivetrain.

When you turn the engine off, at the end of the driving cycle the flywheel would continue spinning for a matter of minutes if no load was applied. Instead of allowing this stored energy to be wasted, it could easily be used to recharge the battery, and converted to electrical energy.

The position of the cylinder heads port in relation to the central journal port determines where induction would occur. Rotary valves are a proven concept.

Look at the Gnome animation by searching the web under the title "animated engines gnome", to understand the function of the original engines.

It sounds like you are assuming a premixed fuel and air charge entering through the port. In a supercharged diesel like the Detroit 2 cycle, the process of allowing air to enter the cylinder, with fuel injected at approximately 23 degrees before TDC is a proven design. With the central journal of a large enough diameter a single injector can be positioned to inject fuel through the cylinder head port at the proper position. I have never seen a Diesel engine that did not use fuel injection. I guess a model airplane engine could be considered an exception, but they are not truly diesel with the heat from the glow plug providing ignition, even after the glow plug is not heated electrically.

We are considering external combustion possibilities, if they prove to be more efficient. We are also considering mixtures of alcohol and water, where the proportion of the combustible alcohol to water allows the complete vaporization of the water, in the cylinder, or in a prechamber then into the cylinder. The alcohol-water fuel mix diesel is one conceptual configuration, with potential due to the 1600 to 1 expansion ratio of vaporised water at 800 degrees. That temperature is one fourth of normal combustion temperatures, and would address emission concerns in a unique fashion.

The central support bearing that supports the flywheel would be over 4 inches in diameter, with roller bearings of about the same size as the wheel bearings in a tractor trailer. Considering they only have to support the rotating mass of the engine-flywheel assembly, I dont forsee problems there. The tractor trailer wheel and tire are supporting a lot of weight, and are subject to serious impact forces as well, that will not exist in this application.

I enjoy the constructive debate, whether positive or negative, as long as its constructive. This design will be reviewed by some people in Detroit next week, with a feasibility study, and potential investors. Someone referred to a major corporation buying and burying this design. I was made an offer of that type 2 years ago and politely declined. The offer if genuine would have netted me several million dollars, and at times I wonder if it was the right decision to refuse.

This design is unique and feasible, according to the DOE. The reason we see soo many new ideas in the field on engine concepts is the potential fuel savings realised. Reducing our crude oil consumption by 50% returns the USA to self reliance, and saves us 200 billion a year in balance of trade deficits.

Currently you are buying 5 gallons of fuel for one gallons work. The theoretical (and impossible) 100% efficient engine would increase the mileage by that same ratio (5 times the present amount). Of course the present practical limit on efficiency is about 50% in the most efficient engines.
Automotive engines (not diesel) are barely reaching 30% in the best examples.

Roger Pham

Again, Mr. Greenwell, thanks for your most prompt and informative reply. Most automotive text books listed the disposition of heat energy of gasoline piston engine as follow: 35% of total heat energy is lost in cooling water, air and oil; 35% of total energy is lost in exhaust gas; 5% of total energy is lost in engine friction; and 25% of total heat energy is converted to mechanical energy at the engine shaft to power the vehicle. There was never any mention of 50% of energy lost in reciprocating motion of the piston, NOT IN ANY AUTOMOTIVE TEXT BOOK.
For the Wankel rotary engine, the heat energy of gasoline disposition is as follow: 22% to net hp at the shaft, 22% to coolant, 8% to oil cooling, 37% to exhaust gas, and 11% to UNBURNED GAS. So, if you add the 11% of heat energy lost to UNBURNED GAS to the 22% of mechanical energy at the engine shaft, you will get 33%, which is quite comparable to the 25% net hp of the piston gasoline engine plus the 5% lost thru engine friction. So, the Wankel rotary engine, while having no "50% lost of power thru its reciprocating motion" as you have asserted, gains almost nothing in term of efficiency as the result of having no reciprocating motion.
Mr. Greenwell, you can't claim that your engine is any more "rotary" than the Wankel Rotary engine, so why should we believe you that your engine will gain the 50% of efficiency that the reciprocating piston engine has lost thu its reciprocating motion? The physics of a reciprocating piston engine is as clear as daylight: At the engine bottom-dead-center (BDC)the piston has transferred all of its kinetic energy into the rotational kinetic energy of the flywheel by making it turning faster, in a single cylinder engine, while in a 4-cylinder engine, the down-going power stroke piston also sends some of its kinetic energy accelerating the up-going compression stroke of another piston in the same engine. This power is transferred via the crankshaft and the flywheel. The more cylinders you have in an engine, the smaller the flywheel you can get away with and the smoother your engine will run. Thus, a WWII 2-row 28 cylinders corn-cob engine with so many cylinders firing in one revolution, can approximate the smoothness of a turbine engine, with the energy of one piston transfer directly to another piston going opposite direction without major fluctuation in the rotational speed of the crankshaft. Of course, at high rpm, the frequent acceleration and deceleration of the pistons put considerable strain on the piston pin, connecting rod and the crankshaft, so the Wankel rotary engine can turn higher rpm at less risk of engine destruction than in a piston engine, but it is a fallacy to suggest that energy is lost as the result of the reciprocating action of the piston. You can see with your own eyes that in a multi-cylinder engine, the piston movements is like a see-saw action, with complete kinetic energy transfer of one piston to another. Yet, are you aware of any report that multi-cylinder engines are any more efficient than single-cylinder engine? No, NONE WHATSOEVER. Either the kinetic energy of the piston is transferred to accelerating the flywheel in a single-cyclinder engine, thus wide fluctuation in rotation speed of the flywheel, or is transferred into the acceleration of another piston going in an opposite direction with a see-saw mechanism at the crankshaft. Complete conservaton of energy principle.
Please kindly get your engine to run on its own two-stroke Otto cycle, sir, and do careful dyno study of it, and then you'll see.

Barry R. Guthrie

For the third time I don't see how you are going to successfully lubricate the system without emission problems?

Exhaust capture is very difficult.

External combustion is just a poor solution to a serious design flaw.

I agree that you are not calculating BTE correctly.
Air cooling heat losses 30%
Valving losses 2%
Exhaust heat losses 35%
Higher friction from bearing 8%
Resulting BTE = 25

You also may find that your piston seal rings may cause scewed wear on the rings and cylinder walls due to the rotation inertia and centrifugal rotation. You combustion chamber reaction may also be strongly scewed to one side of the piston side. This will result in combustion surface hot spots with higher heat transfer losses and potential heat stress wear and failure.


How can the inventor begin to have any credibility, when he keeps claiming that reprocating engines spend 50% of their energy consumption overcoming the "cost of reciprocaiton"? As Roger Pham pointed out, and I have always understood, the friction losses of a recip engine is in the neighborhood of 5%. Perhaps, if you rev up the engine WITH NO LOAD the frictional component might be significant higher, perhaps that's what the inventor is referring to. But who sits around with an engine running at 3,000 rpm and no load? In any case, it is this most inneficient mode (idling with no load) that hybrids and auto-start technologies are addressing. Meanwhile, my head spins at great speed imaging all the huge problems this concept intrinsically introduces. The inventor refers to DD 2cycle diesel design; venerable as it was, this has been totally phased out recently because of efficiency and emissions issues. The really big question: has even the most rudamentory protoype of this engine been built after years of the inventor's research??? Doesn't sound like it.

Sounds like it's time for me to find and ressurect some long discarded engine concept from the ash heap of history and hope some suckker offers me 2 million.

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