F1technical.net

Hello J.A.W.

You write:
“I'd also note that this thread has strayed off the 2T topic basis lately.”


Here is an intriguing 2-stroke, the PatTwo:



(more at http://www.pattakon.com/pattakonPatTwo.htm )


It combines several unconventional characteristics.

For instance, it minimizes the pumping loss at light loads (as in an Atkinson / Miller 4-stroke).

For instance, it eliminates the thrust load between the piston skirt and the cylinder liner.

For instance, it has a 4-stroke lubrication inside the crankcase.

For instance, the double acting piston performs a pure sinusoidal (harmonic) reciprocation: the position X of the piston can be described as : X = (S/2)*sin(f), wherein S is the piston stroke and f is the rotation angle of the crankshaft.

For instance it is perfectly balanced (as perfectly as the Wankel rotary engine, as perfectly as the best V12 engines).


Unconventional is also the control over the load:

When the throttle valve at the middle of the cylinder (the dark, with the yellow lever) is fully open, the engine idles.
When it is fully closed, the engine runs at full load.

In case of tuned-exhaust things get even more interesting: the peak power can be obtained with the throttle valve fully open. Idle with fully open throttle, peak power with fully open throttle. . .
Isn’t it interesting?
Think how.

Thanks
Manolis Pattakos

Hello all

Quote from http://www.pattakon.com/pattakonPatRoVa.htm :



The above animation shows the cylinder and the cylinder head of a 2-Stroke PatRoVa comprising two rotary valves on the same spline shaft (one for intake / scavenge, one for exhaust).
The cylinder liner is rid of ports.
The two "cavities" are arranged anti-diametrically.
A big bore-to-stroke ratio (bigger even than the 1.91:1 of the Ducati Panigale 1299) enables a "cross-uniflow" scavenging and a reasonable mean piston speed (i.e. reliability) at way higher revs.
The cylinder head has not rev-limit.
In the animation the exhaust ports are almost closed, the intake / scavenge ports are still substantially open (asymmetric timing: the intake opens later than the exhaust and closes later than the exhaust).
With most of the residual gas concentrated into the exhaust cavity, the cold intake cavity can be used for the combustion.

Thanks
Manolis Pattakos

Muniix wrote:

J.A.W. wrote: ........this thread has strayed off the 2T topic basis lately ..

.........all the superbikes are gobbling air and fuel at a rate and levels that produce well over 1,000 hp of heat energy .......No wonder electric vehicle racing is taking off. We need to come up with ways to put liquid/gaseous fuels into contention again. .... When electric vehicles have a near perfect torsional torque and don't have to be designed for economy or performance they can be both at the same time. They are througing down a challenge for ICE to respond to.
With the new Tesla racing class vehicle achieving 0-100 kph in 2.1 seconds, now that is insane, not even F1 can do that and in a body that can seat 5 adults and two children and still have two boots, that is damn impressive.
........My ideas were along the lines of finding a more efficient crank train, with all the recent research interest in offset cranks and gudgens pins. If we can find ways of putting more energy into a single engine cycle and make it as efficient as possible .....
This is what interests me at the moment, clearly research shows that larger cylinders have better volume surface ratio's that assist thermodynamic efficiency.
......Maybe by using a torque filling and damping using mild hybridisation ....... Any Ideas ?

a direct drive EV has deficiencies as a direct drive ICV would have
a fast car type ICV is generally (ie at partial power) inefficient
(having a grossly over-powerful engine, slightly compensated by integral over-gearing/downsizing)

a fast motorcycle type ICV is worse, having by convention no over-gearing and no engine downsizing by turbo and/or hybridisation
natural aspiration, with gas fuelling allowing high heat dilution would be magic in this case .....ie......
at full power/torque demand near-stoichiometric fuelling is used, with leaning progressing to maybe 3 lambda at lower torques
so there's a 'full fat' unimpaired spread of power but with far better economy
far better economy because there's little or no throttling during the 99% of the time partial torque is being used
furthering efficiency by rapidly managing the cooling rate according to leaning
this lean running would be particularly beneficial to the 2 stroke

some rpm-differential boost could be included eg by using part-time electric supercharger drive and near-F1 type multiple DI
differential boost was used in (diesel) truck and locomotive engines greatly to widen the power band to 'constant power' eg Paxman 'Hy-Dyne'

the boosted heat-dilution engine is downsized re. heat loss, but not downsized re. friction eg because of high cylinder pressures with compression
better conrod geometry could help with this, and novel geometry giving SHM would eliminate 2nd order vibration or 2nd order counterbalance shafts
usefully to a motorcycle with solid-mounted/structural engine
as 2nd order vibration w/o counterbalance shafts or elastomer mountings seems to cause offence via resonance in footrests and bars

Hello all.

The Evinrude E-TEC G2:



has not 86mm (as, by mistake, I wrote in a previous post) but 98mm bore and 76mm stroke (1.3 bore to stroke ratio).

Despite its big bore (98mm, i.e. as much as the bore in the F1 engines before the turbo-era), it uses one only spark plug in the center of an open cavity wherein almost all the compressed mixture is concentrated at TDC.

As an extra-over-square engine, it has a substantially bigger over-all surface-to-volume ratio.

However, and despite it is an over-square big-bore single-spark 2-stroke, it achieves better fuel efficiency and emissions than its 4-strokes competitors.


The LiquidPiston rotary has even higher surface-to-volume ratio. As the Evinrude E-TEC G2, it concentrates all the mixture in a compact cavity wherein it is burnt (they claim constant-volume-combustion).

During the combustion (i.e. when the rate of thermal loss maximizes), the actual surface-to-volume ratio is one of the best.

After the combustion the rate of thermal loss drops substantially; the increased surface-to-volume ratio is a problem, but not a significant one.


The stereotype “the smaller the surface-to-volume ratio the better the Brake Thermal Efficiency” is wrong.

One should consider not the overall surface-to-volume ratio but the actual surface-to-volume ratio.


The OPRE-Tilting, for instance, has a big overall surface to volume ratio:



The overall stroke of the first OPRE Tilting prototype:



is 30+30=60mm with a bore of 84mm, which means a bore-to-stroke ratio of 1.4, i.e. just a little bigger than that of the Evinrude E-TEC G2.

However, during the combustion the mixture is concentrated in a quite compact (it can easily be true “spherical”: a part of the sphere on the two piston crown, the rest sphere on the "separator disk") chamber / cavity and is burnt there, minimizing the thermal loss during the period wherein the rate of thermal loss maximizes.

The pulling-rod architecture (during the high pressure period the connecting rods are loaded in tension) offers an additional 30 to 35% piston dwell around the combustion dead center, which calls for more “constant volume combustion” than the LiquidPiston can achieve.

The two spark plugs is a requirement for aviation applications (Portable Flyers etc) for safety.

Thanks
Manolis Pattakos

Hello all.

Roland Cross was mentioned several times in the previous posts.

It would be unfair to not mention his other achievements:

https://bathnewseum.com/tag/cross-manufacturing/

Enjoy the following video:

https://videopress.com/v/0mcTV4bj

The old gentleman was testing Cross rotary valve motorcycles several decades ago.

Thanks
Manolis Pattakos

manolis wrote:Hello J.A.W.

You write:
“I'd also note that this thread has strayed off the 2T topic basis lately.”


Here is an intriguing 2-stroke, the PatTwo:

http://www.pattakon.com/PatTwo/PatTwo_Harm1.gif

(more at http://www.pattakon.com/pattakonPatTwo.htm )


It combines several unconventional characteristics.

For instance, it minimizes the pumping loss at light loads (as in an Atkinson / Miller 4-stroke).

For instance, it eliminates the thrust load between the piston skirt and the cylinder liner.

For instance, it has a 4-stroke lubrication inside the crankcase.

For instance, the double acting piston performs a pure sinusoidal (harmonic) reciprocation: the position X of the piston can be described as : X = (S/2)*sin(f), wherein S is the piston stroke and f is the rotation angle of the crankshaft.

For instance it is perfectly balanced (as perfectly as the Wankel rotary engine, as perfectly as the best V12 engines).


Unconventional is also the control over the load:

When the throttle valve at the middle of the cylinder (the dark, with the yellow lever) is fully open, the engine idles.
When it is fully closed, the engine runs at full load.

In case of tuned-exhaust things get even more interesting: the peak power can be obtained with the throttle valve fully open. Idle with fully open throttle, peak power with fully open throttle. . .
Isn’t it interesting?
Think how.

Thanks
Manolis Pattakos

Maybe one should look at the Zoche Aero Diesels, they exist now two stroke diesels for aircraft, decades of development went into these. You can buy one today.



Many advantages, highly optimised from Germany, a friend of mine held development parts in his hands a decade or so ago.

manolis wrote:Hello all.

The Evinrude E-TEC G2:

http://www.pattakon.com/tempman/Evinrud ... d_Spec.jpg

has not 86mm (as, by mistake, I wrote in a previous post) but 98mm bore and 76mm stroke (1.3 bore to stroke ratio).

Despite its big bore (98mm, i.e. as much as the bore in the F1 engines before the turbo-era), it uses one only spark plug in the center of an open cavity wherein almost all the compressed mixture is concentrated at TDC.

As an extra-over-square engine, it has a substantially bigger over-all surface-to-volume ratio.

However, and despite it is an over-square big-bore single-spark 2-stroke, it achieves better fuel efficiency and emissions than its 4-strokes competitors.

Comparing apples to oranges doesn't work, the na F1 engines were very fuel efficient, they had far superior BSFC figures than the current generation marine engines, Marine engines use mhp, marine hp. Remember one F1 that was rained out, their were concerns that the Safetycar a Mercedes AMG with 100+ litres would run out of fuel before restart. The twin spark bishp rv F1 engine used 6% less fuel again. One has to think of equivelence when doing comparisons, clearly a mistake someone with an engineering or physics degree would not make.

Bishop used their income from patents and supply of machines that manufactured steering components, they know how to write patents, their knowledge in rotary valves in power steering was applied to make a successful brv f1 engine, they unique take on applying rotary valves is what made it work, they went with an axial flow valve, that ran with clearance, its all in their patents, and bishop are the master in writing patents, that was what gave them their $15 million a year research and developent budget.

The LiquidPiston rotary has even higher surface-to-volume ratio. As the Evinrude E-TEC G2, it concentrates all the mixture in a compact cavity wherein it is burnt (they claim constant-volume-combustion).

During the combustion (i.e. when the rate of thermal loss maximizes), the actual surface-to-volume ratio is one of the best.

After the combustion the rate of thermal loss drops substantially; the increased surface-to-volume ratio is a problem, but not a significant one.


The stereotype “the smaller the surface-to-volume ratio the better the Brake Thermal Efficiency” is wrong.

One should consider not the overall surface-to-volume ratio but the actual surface-to-volume ratio.


The OPRE-Tilting, for instance, has a big overall surface to volume ratio:

http://www.pattakon.com/Fly_files/Flyer3a.gif

The overall stroke of the first OPRE Tilting prototype:

http://www.pattakon.com/tilting/OPRE_Ti ... _video.gif

is 30+30=60mm with a bore of 84mm, which means a bore-to-stroke ratio of 1.4, i.e. just a little bigger than that of the Evinrude E-TEC G2.

However, during the combustion the mixture is concentrated in a quite compact (it can easily be true “spherical”: a part of the sphere on the two piston crown, the rest sphere on the "separator disk") chamber / cavity and is burnt there, minimizing the thermal loss during the period wherein the rate of thermal loss maximizes.

The pulling-rod architecture (during the high pressure period the connecting rods are loaded in tension) offers an additional 30 to 35% piston dwell around the combustion dead center, which calls for more “constant volume combustion” than the LiquidPiston can achieve.

The two spark plugs is a requirement for aviation applications (Portable Flyers etc) for safety.

Thanks
Manolis Pattakos

is the Zoche really available ?
afaik it has a reputation for continuous decades of unavailability - the reason I mentioned it to those scheming similar items

Tommy Cookers wrote:is the Zoche really available ?
afaik it has a reputation for continuous decades of unavailability - the reason I mentioned it to those scheming similar items

Ibchecked their website and I see no indication that they've achieved type certification yet, or any indication that they're available yet.

Hello Muniix.

You write:
“Maybe one should look at the Zoche Aero Diesels, they exist now two stroke diesels for aircraft, decades of development went into these. You can buy one today.
. . .
Many advantages, highly optimised from Germany, a friend of mine held development parts in his hands a decade or so ago.”

Which are the advantages?
I only see a conventional 2-stroke in radial arrangement.
Are there any differences?

If you can’t tell the difference, there isn’t any.

What about the lubrication? Who keeps the lubricant from entering into the combustion chamber and from escaping to the exhaust?

Is there any real innovation in the Zoche design?



For comparison, here is a Cross-Radial PatAT 2-stroke aero Diesel:



Quote from http://www.pattakon.com/pattakonPatAT.htm :

“The separating plate at the middle of the piston seals the space underneath the piston crown from the crankcase.

Through openings in the cylinder and in the piston, the pressurized air or mixture enters into the combustion chamber either directly or indirectly (it initially goes into the space underneath the piston crown and then, through a piston port controlled by the connecting rod and then through a transfer port controlled by the piston, it gets into the combustion chamber).

The crankcase has four-stroke lubrication.
The scraper ring at the middle of the piston, above the wrist pin, scraps the surplus of oil from the cylinder liner back to the oil pan, from where it is cleaned and recycled.
The cylinder liner area the scraper ring sweeps, is rid of ports.

As in the four-stroke engines, the tiny quantity of lubricant that passes "above" the oil scraper ring lubricates the compression ring(s).

There are two "asymmetric" transfer ports disposed in series with respective piston ports (which are controlled by the connecting rod); there are also three conventional transfer ports (they open after the exhaust port).

The arrangement with the oil scraper ring fits, among others, with compression ignition (Diesel) engines: efficient lubrication of the crankcase and of the piston skirt (wherein the thrust loads are taken), asymmetric transfer, turbo charging, scuffing resistance etc.

The above even firing Cross-Radial PatAT is as vibration free as the best V8, it has firing intervals equal to those of a V8 four-stroke, it has four-stroke lubrication (plain bearings, forced / splashed lubrication in the crankcase, oil scraper rings), it can utilize a central scavenging pump (a turbocharger, for instance), etc.



You also write:
“One has to think of equivelence when doing comparisons, clearly a mistake someone with an engineering or physics degree would not make.”

You don’t know what it is to be an engineer. Don’t appreciate them more than what they deserve.



You also write:
“Bishop . . .know how to write patents, . . . , that was what gave them their $15 million a year research and developent budget.”

Do you know how it is to apply for a patent, or how the inventor feels when a patent is finally granted?

Isn’t it a pity that after all this millions there is not one running prototype on the roads?



You also write:
“Marine engines use mhp, marine hp”

Marine hp?
Please be more specific.

Thanks
Manolis Pattakos

Hello Muniix

You write:
“Comparing apples to oranges doesn't work, the na F1 engines were very fuel efficient, they had far superior BSFC figures than the current generation marine engines”


In 2004 (the year FIA banned the rotary valves from F1), the cylinder bore was limited to 98mm (i.e. as much as the diameter of the Evinrude E-TEC 250 HO).

With 98mm bore, 3,000cc and ten cylinders, the piston stroke is 39.7mm. This piston stroke is 1.91 times shorter (i.e. almost half) than the stroke of the Evinrude E-TEC G2.

Taking under account the deep pockets on the piston crown of the F1 engine, and the necessarily irregular shape of the combustion chamber, the overall surface-to-volume ratio of a 2004 F1 engine is about 50% higher (or worse) than the overall surface-to-volume ratio of the Evinrude E-TEC G2.


These F1 engines “were very fuel efficient”.
If true, this strongly supports the claim of LiquidPisron (MIT / DARPA / Shikorsky) for high BTE (Brake Thermal Efficiency) despite the extreme overall surface-to-volume ratio of their rotary reverse-Wankel engines.


As for the Evinrude E-TEC G2, it is an important 2-stroke engine because it is the first time a 2-stroke wins the 4-stroke competitors not only in economy but also in emissions, in reliability, in TBO etc.



Talking for 2-strokes, here is one more unconventional 2-stroke design:



More at http://www.pattakon.com/pattakonPatPortLess.htm

Portless cylinder liner.

Long piston dwell (pulling rod architecture) at the combustion dead center for the efficient combustion of the Diesel fuel at higher revs.

True 4-stroke lubrication.

True 4-stroke lube consumption.

True 4-stroke scuffing resistance.

Thanks
Manolis Pattakos

Hello Muniix.

You write:
“Marine engines use mhp, marine hp”

"Marine" hp, if there is such thing, is more difficult to obtain than "road" hp.

Because when Wartsila talks for 100,000hp :



they mean the 100,000hp peak power can be delivered continuously not for minutes, not for hours, not for days, but for weeks and maybe months.

In comparison a car or motorcycle engine, having a peak power of 200hp, most of the time operates at, say, less than 20hp (this is what is required for travelling with 60-70mph on a level highway).

In comparison, when a boat with an outboard Evinrude E-TEC G2 departs with its fuel tanks full, the engine can operate continuously at its peak power for several hours.

In comparison, when a giant merchant ship departs from Sangai China full of containers and goes to the USA, the giant 2-stroke cross-head marine engine can operate continuously at its peak power for weeks.


Here is anothe unconventional 2-stroke of pattakon, the PatMar:



Quote from http://www.pattakon.com/pattakonPatMar.htm :

"The PatMar is a two-stroke port-less through-scavenged crosshead engine having true four-stroke lubrication, true four-stroke specific lube consumption and true four-stroke scuffing resistance.

The problem as defined in Wartsila's(*) Technical Journal, Feb 2010 (click http://www.pattakon.com/tempman/Wartsil ... 2_2010.pdf for the article):
"A slightly more ambitious idea is to apply the four-stroke trunk piston engine cylinder lubrication concept to the two-stroke crosshead engine, i.e. to "over-lubricate" the cylinder liner, apply an oil scraper ring, and then collect the surplus oil, clean it, and recycle it. This will of course be a radical change of concept, and whether or not it is viable remains to be demonstrated, but an outline exists and a patent is pending. The aim is to increase scuffing resistance and to achieve the same low specific oil consumption level as on the four-stroke trunk piston engines."

(*) Wartsila is a global leader in complete lifecycle power solutions for the marine and energy markets

The solution: The PatMar engine applies the four-stroke trunk piston engine cylinder lubrication concept to the two-stroke crosshead engine, i.e. it "over-lubricates" the cylinder liner, applies an oil scraper ring, and then collects the surplus oil, cleans it, and recycles it.
The PatMar not only increases the scuffing resistance of the two-stroke engines, but it achieves the same scuffing resistance as on the four-stroke trunk piston engines.
The PatMar achieves the same low specific oil consumption level as on the four-stroke trunk piston engines"

End of Quote


This is the sixth highly unconventional 2-stroke design (all protected by patents) in this forum page.

And, excluding :

the OPRE dual crankshaft "pulling rod" opposed piston at http://www.pattakon.com/pattakonOPRE.htm ,



the PatOP single crankshaft "pulling rod" opposed piston at http://www.pattakon.com/pattakonPatOP.htm ,



the PatPOC "push rod" opposed piston at http://www.pattakon.com/pattakonPatPOC.htm



and the the PatATeco at http://www.pattakon.com/pattakonPatATeco.htm



I am afraid I am running out of unconventional 2-stroke designs.

Thanks
Manolis Pattakos

Paper describing EFI control parameters providing best efficiency for simple 2T engines in very light aviation use.

http://power4flight.com/wp-content/uplo ... Tuning.pdf

Hello J.A.W.

Quote from your link (http://power4flight.com/wp-content/uplo ... Tuning.pdf ) :

“One of the most useful results of the automatic mapping process is the log of recorded data. This log reveals how the engine performance will change with varying fuel or ignition. The software is capable of reading this log of data and reprocessing it with different parameters. This makes it possible to test the engine in application and make adjustments to the entire ECU map in seconds.
Ultimately, the initial map that is determined on the dyno is not as important as the log of data that enables rapid regeneration of the map.”


The last sentence is “all the money”.
There is no optimum mapping.
A programmer can, based on the log of data, create the “ideal” mapping according a customer’s demands.


The data are collected at “fixed operational conditions”.

This is OK for an ultralight.

When the same engine is tuned for a motorcycle, they should deal with the “transient operational conditions”, too. For instance, the datalogging should comprise relatively fast changes of revs / load (say, as when the motorcycle accelerates on the road with third gear).

Thanks
Manolis Pattakos

'fixed operational conditions' - what are those ??
eg is there correction for relative humidity ? (can't read it as the link is too modern for my PC)

and .....
a useful feature could be software detection of what was called 'carburettor icing'
although FI is less prone (than the carburettor) to icing it can still happen


btw this reminds me that in the early days of unleaded 4 star I had such icing in a car (with a non-standard induction system)
treatment (after diagnosis) involved stopping the car etc
a crucial demo of the KRM Superstreak (race motorcycle) was said to be plagued by icing, which escaped diagnosis at the time