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:
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.
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:
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:
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:
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:
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:
Question:
How many times cheaper is a PatRoVa cylinder head:
as compared to Ducati’s Desmodromic cylinder head of Panigale / Superleggera?
Thanks
Manolis Pattakos