26B E-shaft - where?

[Prof]

Four power strokes per revolution? Hmm, that means you would have to have square rotors, three power cycles per revolution per rotor/housing. As for the crank/e-shaft doing three revs per rotor revolution, I think not!!

Look at the gears on the rotors and on the stationary gears...
 
It really does spin a lot quicker than the rotors !!
 
http://www.teamfc3s.org/info/articles/demystifying.html

[leeroy_25]

I am going to have to read some threads on this as I was of the thinking put two shafts at 90deg to have 4 power cycles. Easier option is presumably to run them so you have two firing at the same time as that would lead for simpler ignition setup and I would guess more torque?
I noticed the setup when I saw the pic before and was going to post the same point!

[Nik da Greek]

having said all of the above, this is a real life example of 2 13bs plumbed together.  The reason he\'s given is for the balancing, and the counterweight removal.  

That guy also alludes to something that may be an issue if you consider the engine as a power source to propel a car, rather than an abstract concept nailed to a bench...tyres

Most of the thinking in bike developement has been concerned with de-evolving their power source, since it reached the point where making embarassing amounts of power was easy, but the means to control it and put it to the ground was occult at the least. Traction control is easier in a car where you have more space and surplus electrical supply for clever electronics, but the simple fact is that evenly spaced power pulses simply so not give tyres time to recover from a state of slip quickly enough. This problem is exaggerated by two-strokes, with their power stroke per revolution, and after all, rotaries are kinda two strokes that go roundy roundy rather than uppy downy...

What tends to happen is that the tyre loses traction, and just physics catches up and attempts to restore it again, BANG comes another power pulse to keep it slipping. Few two stroke GP bikes still ran even firing orders by the time they were made obsolete by MotoGP tech, and some of those still run staggered cranks, even with clever electrickery the two strokes could only dream of. Yamaha\'s all-conquering 2009 R1 also has a cross-plane crank to unevenly space the firing order and give the tyres a chance to catch up, so it goes BANG-BANG pause BANG-BANG with the pause allowing traction to be restored (hence the other term they are known by of "big bang" engines).

I know cars have another advantage in that they can fit ever more mahoosive tyres, but there are limits to this dictated from, for example, race series rules and the physical constraints of the vehicle to which the engine is fitted, presumably in this case some sort of RX chassis. The constant struggle for traction also has knock-on effects not just in terms of sheer diffculty controlling the vehicle, but also wear and tear to drivetrain and suspension componentry from being in a constant state of conflict between fairly large forces of moment.

There would be an argument for having the correct engine characteristics to promote maximum grip, rather than to overwhelm it and then try to backtrack to the tipping point. That old Pirelli slogan is hackneyed but never out of fashion after all.....unless you want to build a drift car, of course, in which case being able to provoke a break in traction at will would seem a definite advantage.


Or, of course, I could just be spouting abject boIIocks as usual

[Bob Monkhouse]

Humble apologies, not being a big expert on rotarys I\'m obviously wrong on the rotor/e shaftratio, a good example of commenting without thinking!! As for the four power strokes I\'m probably getting hold of the wrong end of the stick(a case of not really paying any attention to what the thread is all about)-der! As for firing orders on four strokes, Ducati ran what was called at the time a \'big bang\' v-twin where the firing order was only a matter of a few degees out on each cylinder(ie. the pistons instead of firing 180degrees apart as is usual). I\'m not sure if they still use this but it was effective a couple of years ago.Anyway, give me  a two stroke any day of the week! (And before you start moaning, yes I love rotarys almost as much, its just I don\'t have enough knowledge of them yet)!!!!

[Nik da Greek]

Yeah, you\'re kinda right, Bob. In fact, all Ducatis since the first "proper" ones back in the days of Pantahs and such have intrinsically been "big bang" because they share a 90 degree V-twin engine layout (or L-twin as Ducati call it). Therefore, it\'s got a built-in bang-bang-pause firing order. one of the reasons for their legendary grunt out of corners and good traction, although the catering bean-tin size pistons flailing around help no end. Two strokes for the win, BTW!

[Bob Monkhouse]

I was talking to Jim Whittam the other day (ex superbike champion- I\'ve known him since he was a spotty teenager throwing mopeds down the street) and Nortons rotary came up. They are actually remaking the engine(something Carl mentioned to me a while ago) and, though they are increasing the capacity(573cc? to 7-something)the general design of the engine will remain the same. Oops. I\'d better start another paragraph before someone starts moaning!!
 To me the main downfall of the Norton engine is the mains-large needle rollers(and I mean large) needing 20:1 petroil mixture. They smoke like ....! Jim Whttam was a bit surprised that the engine is being manufactured again coz there ain\'t no class to put it in, a bit like making a 500cc GP engine again(two stroke I mean) though it would .... all over any four stroke about!!!

[Bob Monkhouse]

Going back to the 4 rotor e-shaft, the only way to successfully marry two shafts together would be a keyed taper. With splines or serrations there is still chance of some backlash which might be ok on a halfshaft but not a crank-e shaft.