2 stroke thread (with occasional F1 relevance!)

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
gruntguru
563
Joined: 21 Feb 2009, 07:43

Re: 2 stroke thread (with occasional F1 relevance!)

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wuzak wrote:Alternatively, it could be arranged as for the Jumo 222, where pairs of cylinders fire to mimic a 3 cylinder radial. That is,
1, 2, 5, 6, 3, 4.
. . . but only possible with multiple banks. . . . or single bank, multiple crankpins.
je suis charlie

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

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Hello.

The conventional Radials have more significant problems than the firing order.

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

The following even-firing Cross-Radial:

Image

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.

Image

In the above animations they are shown the moving parts of a Cross-Radial PatAT from various viewpoints. The connecting rods and the pistons are properly machined to provide wide bearing surface wherein the heavy loads are taken, keeping at the same time the piston bore low and the crankpin short. A single plane bearing (the yello part around the crankpin) serves all the connecting rods "unconventionally" (it rotates inside their big ends, being secured to the crankpin).

In comparison to the convetional Radial engine:

Image

the Cross-Radial with the four cylinders and with the forked connecting rods is a true "vibration free" engine (better balanced than the "master-slave-rods" Radial regardless of the number of cylinders of the later), it is also a true "symmetrical" engine: all the four cylinders run under the same conditions: same piston stroke, same piston motion profile, same connecting rod leaning (thrust loads), etc.
As the Radial.exe demonstrates, a typical Radial (master rod / slave rods) cannot help running with substantially different piston strokes in different cylinders.”

End of Quote.


More important than the uneven firing is the uneven way the various cylinders of a conventional Radial operate. With the master cylinder arranged at the top of the conventional Radial engine, the pistons in the “side” cylinders perform a stroke of about 10% longer than the stroke of the piston in the “master cylinder”, with the cylinders at the one side compressing substantially faster and with the cylinders at the other side expanding substantially faster.


The 2-stroke PatAT Cross Radial turbocharged Diesel:

Image

is both: even firing (90 crank degrees between consecutive combustions) and perfectly “uniform” as regards its cylinders: the reciprocation performed by a piston is identical with the reciprocation performed by any other piston.
It is also more “vibration-free” than the best 4-stroke V-8 engines.



As for the Radial PatRoVa:

Image

There is a front cross (comprising the two vertical and the two horizontal cylinders) wherein all the four pistons, by means of four forked connecting rods, use the same crankpin of the crankshaft, just like in the previously described 2-stroke PatAT Cross Radial.

According the previous analysis of the Cross Radial 2-stroke PatAT, each Cross alone is “perfectly balanced” and its pistons perform the same exactly reciprocating motion (same stroke, same piston motion profile, same leaning of the connecting rod relative to its cylinder axis etc).

At the back cross (comprising the four diagonal cylinders) of the eight cylinder PatRoVa radial. The bottom left cylinder is at its TDC (at its TDC is also the top cylinder of the front Cross), i.e. the crankpin of the back Cross is 135 degrees apart from the crankpin driving the pistons of the front Cross.

Is it now obvious that this 4-stroke Radial is even-firing?

The “asymmetry” of the crankshaft (the two crankpins are at 0 and 135 crank degrees) doesn’t matter at all, because each Cross, alone, is “perfectly balanced” as regards its inertia vibrations.

Putting the two Crosses at 45 degrees from each other, what you get is the uniform cooling of all cylinders: the front ones and the back ones.


The simple structure of the valve train (one moving part per cylinder and nothing else, with the “one moving part” performing a smooth rotating motion) and the fact that the valves can never hit the piston, enhances the safety.


So, take another look on this 4-stroke 2-row Radial engine with the PatRoVa rotary valves on its heads and find disadvantages.



Quote from a previous post:

“On the other hand, the PatRoVa seems capable to bridge the gap of specific power between the 2-strokes and the 4-strokes, keeping the good characteristics of both schools.

For instance, the Panigale 1199 Superleggera (60.8mm stroke, 112mm bore, 200PS at 11,500, red line at 12,500rpm (the most expensive motorcycle in the world) puts the Desmodromic valvetrain of Ducati at its limit.

What if the bore was increased at 120mm (the Panigale 1299 has 116mm bore), the stroke was decreased at 50mm (1,130cc capacity) and the desmodromic cylinder heads were replaced by PatRoVa ones of higher flow capacity?

For the same mean piston speed, the red line goes from the current 12,500rpm at 15,000rpm. And if the underneath mechanism (crankcase, crankshaft, connecting rods, pistons) can stand a little more revs (the cylinder heads can operate at way higher revs, say at 25,000rpm) a power of 220PS per liter seems attainable.”

End of Quote


Unless I am wrong, the core idea behind the Desmodromic systems is the elimination of the valve springs.

It is supposed the Desmodromic heads of Ducati Panigale need not valve springs:

Image

Don’t get confused; the big springs shown are not valve springs; they are on the rocker arms that control the opening and the closing of the valves!

The PatRoVa rotary valve is a true Desmodromic valve train wherein the rev limit is more than double than the rev limit of any Desmo / Desmodromic system:

Image


Question:

How many times cheaper is a PatRoVa cylinder head:

Image

Image

Image

as compared to Ducati’s Desmodromic cylinder head of Panigale / Superleggera?

Thanks
Manolis Pattakos

wuzak
434
Joined: 30 Aug 2011, 03:26

Re: 2 stroke thread (with occasional F1 relevance!)

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gruntguru wrote:
wuzak wrote:Alternatively, it could be arranged as for the Jumo 222, where pairs of cylinders fire to mimic a 3 cylinder radial. That is,
1, 2, 5, 6, 3, 4.
. . . but only possible with multiple banks. . . . or single bank, multiple crankpins.
Yes, for even firing.

wuzak
434
Joined: 30 Aug 2011, 03:26

Re: 2 stroke thread (with occasional F1 relevance!)

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manolis wrote:The following even-firing Cross-Radial:

http://www.pattakon.com/PatAT/PatAT4.gif

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.
Hi Manolis.

Am I correct in stating that this layout can be only even firing because it is a 2-stroke?

FWIW there were some X engines built between WW1 and WW2 and during WW2.

One of the first was the Napier Cub - but it didn't have the banks displaced equally. It used, like the Lion, master and slave rods.

Allison built the X-4520 from a USAAC design.
https://oldmachinepress.com/2013/06/16/ ... ft-engine/

That used fork and blade rods, with the upper pair of banks having one set and the lower set of banks another set next to the first. It meant that the upper and lower banks were offset.

As was the case with the Rolls-Royce Eagle XVI of the mid 1920s. This was an X-16 that didn't go into production.

Other Rolls-Royce X engines used master and slave rods (Exe, Vulture, Pennine). I believe so did the Daimler Benz DB604.

In any case, the point being that for multiple row engines your arrangement might be too bulky. For a single row machine, as you have shown there, it works fine.

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

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Hello Wuzak.

You write:
“Am I correct in stating that this layout can be only even firing because it is a 2-stroke?”


If you mean the single row Cross Radial (4 cylinders in a Cross arrangement): yes, you are correct, provided you are limited in single crankpin crankshaft.

As 4-stroke, and with a unique crankpin, it cannot be even firing.

Theoretically, on the other hand, by the “correct” crankshaft (crankpins at 0, 270, 180 and 90 degrees) you can turn it to even firing. But you need double connecting rods per piston (to avoid bending loads), the crankshafts gets too flimsy and complicated, the size of the crankcase gets more than double, etc, etc, making such a “solution” worthless.


With a second row (i.e. one more 4-cylinder Cross Radial) you have an even-firing 4-stroke 8-cylinder PatRoVa:

Image

as explained in my previous post



You also write:

“In any case, the point being that for multiple row engines your arrangement might be too bulky. For a single row machine, as you have shown there, it works fine.”

No.

If you talk for an 8-cylinder double-row 2-stroke PatAT, the two crankpins are arranged at 0 and 180 crank degrees, the intermediate balance webs can be eliminated reducing the overall length of the engine (the axial offset between the two rows), and the engine remains extremely compact and lightweight.
The overall width of each crankpin (whereon the four forked connecting rods are rotatably mounted) is less than the cylinder bore.

What makes you think it “might be too bulky?”

Alternative, instead of adding a second row, you can double the capacity of the single row (the PatAT Cross Radial is a Diesel driving directly the propeller).

By the way, the unconventional arrangement of the forked connecting rods allows the use of a single unconventional plain bearing secured on the crankpin for all the four connecting rods.

By the way:
the PatAT Cross Radial is a loop-scavenged 2-stroke engine that provides as much asymmetric transfer as desirable (if desirable, the transfer can close after the end of the exhaust), without introducing the problems of the Opposed Piston engines, like the Junkers Jumo 205 and the Achates Power modern version of it:

Image

wherein the phase difference of the two crankshafts overloads the synchronizing mechanism (weight, friction, vibrations etc), wherein the access to the combustion chamber (for the injection) is difficult (if you put a narrowing in the center of the combustion chamber of the Achates Power OP, like, say, the narrowing in the following OP PatAT:

Image

you destroy the through scavenging), etc.



If you talk for the 4-stroke 8-cylinder PatRoVa, I can’t see how a double row Corss Radial “might get too bulky”.

Please be more specific.

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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wuzak wrote:
gruntguru wrote:
wuzak wrote:Alternatively, it could be arranged as for the Jumo 222, where pairs of cylinders fire to mimic a 3 cylinder radial. That is,
1, 2, 5, 6, 3, 4.
. . . but only possible with multiple banks. . . . or single bank, multiple crankpins.
Yes, for even firing.

& none of which actually made the cut, for real production/service use - by dint of one reason or another..
(Likely the Napier Cub got around some of those inertia dynamics/harmonics running problems by its asymmetry).
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

User avatar
Andres125sx
166
Joined: 13 Aug 2013, 10:15
Location: Madrid, Spain

Re: 2 stroke thread (with occasional F1 relevance!)

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J.A.W. wrote:
Andres125sx wrote:2 stroke 500cc bike for Isle of Man???

OMG some people need a doctor ungently! :mrgreen: :lol:
Somehow I doubt that Yamaha would let "The Doctor" race there, on anything..

& FYI Bruce Anstey got the 'classic' lap record at the IoM last year - on a 2T YZR 500 @ a 200+ km/h - average speed..
I know they´re fast, but they´re difficult to tame too and we all know how dangerous IoM is.

BTW, IMHO IoM is similar to MX, the bike is not that relevant, it´s the rider. Like a friend of mine always said, it´s not the arrow, it´s the indian (not sure if it makes sense in english tough)

Also, for IoM big manufacturers are not deeply involved, and without huge resurces tunning a 2T is way way cheaper and easier than tunning a 4T

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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Andres125sx wrote:
J.A.W. wrote:
Andres125sx wrote:2 stroke 500cc bike for Isle of Man???

OMG some people need a doctor ungently! :mrgreen: :lol:
Somehow I doubt that Yamaha would let "The Doctor" race there, on anything..

& FYI Bruce Anstey got the 'classic' lap record at the IoM last year - on a 2T YZR 500 @ a 200+ km/h - average speed..
I know they´re fast, but they´re difficult to tame too and we all know how dangerous IoM is.

BTW, IMHO IoM is similar to MX, the bike is not that relevant, it´s the rider. Like a friend of mine always said, it´s not the arrow, it´s the indian (not sure if it makes sense in english tough)

Also, for IoM big manufacturers are not deeply involved, and without huge resurces tunning a 2T is way way cheaper and easier than tunning a 4T
Not much "tunning" it done on MX tracks, but the record average speed at the IoM has been over the old 'ton' for more'n 1/2 a century..
..so much for that oddly fanciful analogy..

Funnily enough, B. Anstey's performance has got him an IoM ride on a big ole 4T Moto GP Honda this year..

Thing about racing 2T G.P. bikes, their quick response/low inertia engine characteristics rewarded the top-flite riders..

It is true though, that racing 4T MX has become too expensive for self-financed riders..
Yet Bruce Anstey has a super-pricey Honda Moto GP (4T) machine to ride at the IoM this year,
Honda do put quite a bit of effort in to IoM racing..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Tommy Cookers
617
Joined: 17 Feb 2012, 16:55

Re: 2 stroke thread (with occasional F1 relevance!)

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@ Manolis

conventionally one might imagine 3 cylinders/row for a small radial (with 3 rods of course)

also iirc there was a small 4 cyl 'flattened X' format engine ie with very unequal bank angles maybe 40, 140, 40, 140 deg
oriented like a flat twin ie all cylinders getting a direct air stream
(maybe for a target drone ?)


the conventional radial is surely sufficiently vibration-free for any practical purpose ?
(suprisingly so for 600-800 hp or more, and remember the Detroit bigblock V8 has been tried as the basis for a replacement)

as there's vibration from mechanical effects of the propellor
and vibration from aerodynamic effects of the propellor
eg temporary engine detonation will occur in normal flight with any hasty coarsening of prop pitch
(prop-cyclic variation of blade drag exciting crankshaft torsionals big enough to oscillate of magneto advance/retard ?)
and AoA-related cyclic vibration in yaw and crank-torsion occurs throughout flight with any 2 blade propellor, fixed or variable pitch
and it will be larger at the large AoA of all takeoffs (and more widely in sporty flying)
a 3 blade prop will vibrate crank-torsionally

additional to the question of even firing intervals (though some departure from this may be manageable) .....
master/slave rod radials with odd numbers of cylinders seem to be more compact (than they would with even numbers of cylinders)

given that aircraft engines have short rods for compactness, rod/crank geometry seems important ....
though conventional radials are not particularly good wrt 'side thrust' effect on piston friction (contrary to advertisement re gas-fuelled generation)
some articulated rod arrangements benefit V engines in this regard (and, potentially, X and 'flattened X' engines)


btw - Tempest/Sabre fans might consider the far cheaper and better MB 5

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

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Hello Tommy Cookers.

The vibration-free quality of a single-row (one crank pin) three-cylinder Radial is not good (there is a second order unbalanced rotating inertia force, also a significant inertia torque etc).
The Radial-3 is worse than a V-90 two-cylinder like, say, the Ducati Panigale.

The two cylinder “Radial” (i.e. a flat, but not boxer, twin) is even worse.


The vibration-free quality of a single-row four-cylinder Radial like the PatAT:

Image

wherein they are used forked connecting rods (and not master rod – slave rods architecture) can be regarded as perfect. It is better than the best 4-stroke 8-cylinder engines.
To put it differently: take the best V-90 8-cylinder engine you know. The PatAT 4-cylinder Radial is better. As for their firing intervals: they are both even-firing with 90 crank degrees between successive combustions.

If you want to keep the even-firing in case of 4-stroke Radial, you need a second row as described in previous posts.


The conventional Radial aero engines have, in comparison, a lot of vibrations (in some cases, the big aero Radials were using external balance shafts to reduce the vibrations).

Worse than the vibrations in the conventional Radial engines (articulated con-rods) is the asymmetry of the various cylinders.
If you have windows open the http://www.pattakon.com/PatAT/Radial.exe exe animation and see the stroke of the various pistons. The length of all the black radial lines equals to the stroke of the “master” piston. The side pistons perform a substantially longer stroke (some 10%).

(Imagine optimizing (in terms of volumetric efficiency, of emissions, of vibrations, of rev limit etc) a 4-in-line conventional auto-engine having different strokes in the four cylinders.)

Then press the c key on the keyboard. The brown radial line represents the overall inertia force resulting by the motion of the pistons. Depending on the angle of the crankshaft, it varies significantly, which means the two balance webs on the crankshaft cannot completely counterbalance it. Not good if you want to use the most lightweight frame.


With four cylinders per row you have perfect vibration-free quality.
The same is true with five, seven, nine, eleven etc cylinders per row, but it becomes from difficult to impossible to use conventional connecting rods (and not master-slave ones which generate significant problems as explained).

In a single row 4-cylinder PatAT turbocharged Diesel, the asymmetric transfer of the PatAT helps the turbocharger to efficiently scavenge the cylinders and to trap into the cylinders a lot of air.
The transfer gets as asymmetric as in the Opposed Piston engines (Junkers Jumo, Achates Power etc), without the side effects of the conventional Opposed Piston engines (heavy crankshafts, heavy synchronizing mechanism, friction, cost, compactness etc).

The PatAT is a 2-stroke, however it has 4-stroke lubrication of the crankcase and of the lower side of the cylinder liners wherein the thrust loads are taken (the oil scraper rings never pass over ports), which reduces the friction and the specific lube consumption.

See in the animation the yellow plain bearing under the big ends of the four connecting rods.

A single plain bearing can serve all the four forked connecting rods.

As you see, a 2-stroke PatAT Cross Radial turbocharged Diesel concentrates a lot of significant advantages and avoids several disadvantages of the prior art aero engines, making it a good solution for airplanes, light airplanes, helicopters etc.

Objections?

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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Manolis, remakable stuff, as usual..

T-C made mention of the Martin-Baker MB 5, I 'm guessing it might be in relation to the contra-rotating Rotol prop system..
..which may be of interest, so for diagram/section drawings see here, below:
http://www.flightglobal.com/pdfarchive/ ... 02363.html
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Tommy Cookers
617
Joined: 17 Feb 2012, 16:55

Re: 2 stroke thread (with occasional F1 relevance!)

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PC Vincent of the famous V twin Vincent motorcycles once suggested in 'Motorcycle Sport' magazine ........
that the 3 cylinder radial was good for motorcycles
this just after the 90 deg V twin Guzzi and Ducati (and BSA/Triumph 3 cyl inline) had appeared
and decades after the 90 deg V British 250 cc Panthette motorcycle etc

PCV had designed a very efficient 2 stoke fitted to 'air droppable' lifeboats on WW2
and was then working on a novel iirc free-piston ? 2 stroke rotary engine for eg 25000 rpm


there was in the USA a 1 throw (ie non-boxer) flat twin made for rudimentary ground trainer (non-flying) aircraft
later even used by amateurs in flying aircraft (though sometimes converted to a boxer, with rods bent to reconcile crankthrow offset)

the 22 cyl Siemens (-Shukert?) rotary (radial) engine had 2 rows of cylinders in opposite rotation (at half 'engine' rpm - also the prop)
so giving full cancellation of engine vibration forces (and gyroscopic effects, of course)

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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Tommy Cookers wrote:PC Vincent of the famous V twin Vincent motorcycles once suggested in 'Motorcycle Sport' magazine ........
that the 3 cylinder radial was good for motorcycles...
PCV had designed a very efficient 2 stroke fitted to 'air droppable' lifeboats on WW2
To be fair T-C, that interesting 2T lifeboat mill ( utilizing PCV's patented ideas) was actually made metal by P. Irving..

& a 120' 3 cyl radial is surely going to present packaging problems in a bike chassis..

I have seen an 2T opposed piston 120`radial triple though.. kind of an inside out Napier Deltic..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

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Hello Tommy Cookers.

You write:
“PC Vincent of the famous V twin Vincent motorcycles once suggested in 'Motorcycle Sport' magazine ........
that the 3 cylinder radial was good for motorcycles
this just after the 90 deg V twin Guzzi and Ducati (and BSA/Triumph 3 cyl inline) had appeared
and decades after the 90 deg V British 250 cc Panthette motorcycle etc”


Here are the plots of the free inertia force and free inertia torque of a conventional Radial-3 with forked connecting rods (not master – slave, forked):

Image

Image


Here is the comparison of the above Radial3 with a V90 2-cylinder (like, say, a Ducati Panigale Superleggera) for same bore, same stroke, same connecting rod, same piston:

Image

Image

The unbalanced inertia force of the Radial3 is a rotating 2nd order force, while the unbalanced inertia force of the V90 2-cylinder is “flat”, on a plain normal to the bisecting plain of the Vee.

The unbalanced inertia torque of the Radial3 is about double as compared to the unbalanced inertia torque of the V90 2-cylinder (OK, with same bore and stroke the V90 has the 2/3 of the capacity of the Radial3).

The only advantage of the Radial3 is its even firing (120 crank degress if 2-stroke, 240 crank degrees if 4-stroke).


And here is the comparison of the free inertia force and free inertia torque of the Radial3 versus a Radial4 (say, the PatAT Cross Radial):

Image

Image

The free inertia force of the Cross Radial is actually zero (while the Radial3 suffers from a heavy rotating 2nd order unbalanced inertia force).

The free inertia torque of the Radial 3 (it is of 3rd order) is several times (almost ten times) bigger than the free inertia torque of the Corss Radial 4-cylinder (which is of 4th order: count how many times it maximizes during a complete crankshaft rotation).


Provided the connecting rods are forked connecting rods, as in the PatAT Cross Radial arrangement (the forked connecting rods eliminate the inertia moment of a Radial), according the math and the physics the Radial-4 (or cross radial) is almost perfect and you gain nothing to go to more cylinders (except the smaller intervals between successive combustions).


As you see, the transition from a Vee90 2-cylinder to a Radial3 is not an improvement, or, at least, not a clear improvement.
According the theory, a V90 2-cylinder appears not inferior as regards its vibration-free (inertia vibration-free) quality relative to a Radial3 of the same capacity.


In comparison, the transition from a V90 2-cylinder or from a Radial-3 to a Radial-4 (or Cross Radial) is a substantial improvement as regards the vibration-free quality. And because the Cross Radial 4-cylinder is almost perfectly rid of inertia vibrations, more cylinders add nothing to smoothness.


If you look carefully at this animation (the connecting rods of the PatAT Cross Radial):

Image

you can see two pairs of forked connecting rods: cyan and green the one pair, magenta and blue the other pair.

The surface of the big end of each connecting rod towards its piston (i.e. whereon it bears heavy load) is substantially bigger than the surface of the other side of the big end (which bears substantially weaker load).

With the red “valves” at the extensions of the connecting rods (and with respective ports made on the pistons and on the cylinder liner) the PatAT Cross Radial achieves the asymmetric transfer of the Opposed Piston aero engines, being by far more lightweight than the Opposed Piston engines: it has one only short crankshaft with a unique crankpin, it needs not synchronizing mechanism, etc, etc.

There is not yet a functional prototype of the PatAT Cross Radial.

According the experience from the other pattakon prototype Diesel engines, a 2 liter PatAT di Diesel turbocharged Cross Radial is expected to have a weight of some 80lb (35kg).
Ans as a heavily supercharged Diesel, it is expected to be able to provide some 300PS (the 2 liter Diesels for the BMW cars make some 200PS and they are 4-stroke engines).
With low specific lube consumption and low emissions, the PatAT Cross Radial can reasonably be the prime mover not only for airplanes / helicopters but also for trucks. Boats etc.


Thanks
Manolis Pattako

Tommy Cookers
617
Joined: 17 Feb 2012, 16:55

Re: 2 stroke thread (with occasional F1 relevance!)

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well, I thank you for that .......

the 4 bank approach was (in)famously used by RR in the WW2 4 stroke 24 cyl Vulture (and the 2 stroke Exe and Pennine)
these had what I earlier loosely called an asymmetrical master/slave rod arrangement (ie rod split plane 45 deg not 90 deg to the master)
so all the slave rods gave equal geometry, unlike most conventional radials, as you say
in running behaviour geometrical differences wrt the master rod could simply be compensated in CR (were they ?)
had the UK known of the US development of silver-plated shims between (radial) split rod mating faces the Vulture could have been saved

mep variation could occur without rod geometry differences eg iirc D-B V12s used bank-differential CR to compensate for this
mixture maldistribution was anyway a general and bigger issue than any rod geometry-related issues
with modern sensors and control intelligence there is little problem compensating running behaviour for geometrical differences


with the ever-continuing (30 year) unavailability of Herr Zoche's 4 bank 2 stroke CI radials ......
there still seems to be a few (2 stroke CI) engines around (using 'jet fuel' of course)
eg the WAM 4 cyl inverted turbocharged etc inline 167 max hp, 158 kg complete, typical bsfc 0.4 lb/hp-hr

the current and earlier episodes of low oil price must be an irritant to would-be CI engine manufacturers
where does this stand relative to the recent emergence of JI, enabling boosted very lean SI running for high power and efficiency ?

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