2 stroke thread (with occasional F1 relevance!)

[Rodak]

nz, thanks for you illuminating post above. I reread it and realized the truth of what you wrote; manolis has no intention of actually building his 'flyer'. This is just a thought experiment with him and that's why he won't (or can't) provide basic data; he has none. I am of the 'experimentalist' faction and didn't realize manolis, with his pictures of castings, etc. has no intention of actually building and strapping (or gluing, you choose) this contraption to his torso and starting the engine. It's all a giant word salad ®.

[J.A.W.]

nz, thanks for you illuminating post above. I reread it and realized the truth of what you wrote; manolis has no intention of actually building his 'flyer'. This is just a thought experiment with him and that's why he won't (or can't) provide basic data; he has none. I am of the 'experimentalist' faction and didn't realize manolis, with his pictures of castings, etc. has no intention of actually building and strapping (or gluing, you choose) this contraption to his torso and starting the engine. It's all a giant word salad ®.

FYI, 'word salad' is a descriptor term relating to symptoms of psychotic thought-disorder*,
it is both an improper, & unkind, slur towards Manolis, regardless of his personality 'quirks'.

It is clear that Manolis is a progressive, by pioneering a new personal thrill/transport/sport
machine, one which just happens to be of thread topical interest, given the inherent attributes
of the 2T engine as a 'natural fit' for this purpose, & also showing us why neither battery-electrical,
nor gas-turbine power sources really are practicable alternatives...

(If motorcycles had not been invented already, I'd reckon you'd be doomcasting them, too)...

* An observer with an experiential knowledge of/interest in, 'spot the looney' (per Monty Python)
might well ascribe 'pathological envy/jealousy' as a motivation for the relentlessly reiterated OTT
mocking/nit-picking posts by some members here (who'd do better by offering constructive critique
- if not actually meaningful support - rather than emotive diatribes decrying/deprecating his efforts).

[uniflow]

There's a bunch of other stuff that's required but probably the biggest common attributes of inventors who end up making a real difference are 1) the ability to work with other people and motivate other people to work with them; and, 2) the humility to see value in other people and the ability to listen, learn and adapt.

There are millions of inventors and backyard tinkerers who have fantastic ideas that never get anywhere because they are too introverted, closed minded, arrogant or defensive to work out how to engage with others. Introversion is forgivable, not everyone is wired to engage with others, the other characteristics well . . .

Or the ' inventor ' realises he going to get screwed over anyway, and just releases it to the internet, rendering it not possible to patent by anybody, case in question TPI.
KTM, after pinching the idea, tried to belatedly patent TPI last year. Myself and TM successfully stopped their application as it was obvious where the technology came from. TM now is free to also produce TPI ( and they do )
I've got nothing from all this apart from bragging rights and allegedly a TM motorcycle. I will believe that when I see it. At least TM will communicate with me, KTM pretend I don't exist.

[nzjrs]

Sorry, What is TM?

[Big Tea]

edit and delete. Sorry guys messed up please ignore it

[joshuagore]

It's maybe interesting for people to know that in my world of seed stage venture capital it's often said that ideas are worthless. People who make great founders and entrepreneurs, who take ideas and both make them real but also take them to scale and sustainability need more than just ideas.

There's a bunch of other stuff that's required but probably the biggest common attributes of inventors who end up making a real difference are 1) the ability to work with other people and motivate other people to work with them; and, 2) the humility to see value in other people and the ability to listen, learn and adapt.

There are millions of inventors and backyard tinkerers who have fantastic ideas that never get anywhere because they are too introverted, closed minded, arrogant or defensive to work out how to engage with others. Introversion is forgivable, not everyone is wired to engage with others, the other characteristics well . . .

I agree with this sentiment completely. I spend a lot of time hearing out 'new ideas' which are often only new because those working on the idea rationalized a closed shop due to fear of theft(this is almost always a fear of being wrong, or meeting an expert who knows more) and subsequently never learned what they were doing had been done 100x before, and had undergone incremental prototype improvements and production in other hands. I used to just design for whoever payed, but after awhile you begin to realize some people create what I call 'retirement projects', or projects they intend to pursue, indefinitely, without a goal following any rules of capital and thus never leading to any profit. I now only work with customers who have buy in from the top down, meaning from financing to manufacturing, and sales, everyone is winning to some degree and every vendor in the mix has skin in the game. If a person doesn't have that sort of buy in vertically I can help them where gaps exist, but if too many gaps exist, I'm skeptical the 'inventor' has skipped steps or attempted to not look directly into the sun. Whenever I hear an 'inventor' claim a vendor is bad because they told them 'we cant do that', I see a red flag. Too many red flags and I can't see a destination worth pursuing. If I meet the 'inventors' financer and they seem aloof or passively interested in the projects success... red flag. Everyone top down has to be focused on making something great and making money doing it. Maybe 1 in 10 projects get all those to align, and this applies to major OEM's, many of their ideas fail to fly as well(you just don't hear about it). I highly recommend the individual inventor use the leverage of their results to motivate creating shared co-operation towards their goal, and to do this much earlier in the process than they feel comfortable. They may just avoid going down a long journey for which when they arrive nobody will be standing around them(no chance of success), if they can arrive at all without help. Another note, the most trivial things you buy and use may have had an individual inventor championing that solution for years before the widget hit your hands. This individual inventor could be an engineer at GM, working their entire career to integrate a new technology and only being able to do so when they worked to be engineering manager, or a project lead. Ohh also I have never designed anything that has flown.... yet(maybe soon, still in construction). Not unless you consider going very fast close to the ground flying. Also if it isn't obvious I made a ton of the above mistakes and still do, it is only the great people around me and those who have bought in on my projects that keep me pointed true north, because how do I know I am getting good advice? When the people around me stand to benefit when the culmination of our work leads to shared profits. If they lie to me they suffer too.

[uniflow]

Sorry, What is TM?

Italian motorcycle and kart engine manufacturer.
TPI, Transfer Port Injection

[manolis]

Hello all.

Does anybody know why the KTM TPi engines are not yet(?) used for street motorcycles, or even for small cars?

What is the real technical issue?

Thanks
Manolis Pattakos

[manolis]

Hello all.

Quote from another forum:


Hello Gruntguru

You write:
“What will be the effect of the Pat VVD on torsional vibration of the crankshaft? On a simple level it is clear that the "inertia torque" at a given crankpin will have an excitation frequency of twice the crankshaft speed. (It is useful to note that this forcing is removed "at the crankpin" - ie it no longer applies a "twist" to other sections of the crankshaft, unlike inertia torque canceling due to opposite phase cylinders etc.)

With inertia torque removed at the crankpin, the major remaining excitation (combustion) is at half crankshaft frequency - ie 1/4 the frequency of the inertia torque.

Surely this will improve durability and simplify crankshaft design?”[/ι]


The dominant frequency order of the inertia torque is 2 (two times the frequency of the crankshaft rotation).

There is a combustion pulse per 180 degrees of crankshaft rotation. This means a combustion pulse frequency of order 2.
However the combustion pulses, depending on which cylinder burns / expands, cause different angular twist of the crankshaft.

Suppose the angular twist of the crankshaft is defined as the angle of the crankpin of the 1st cylinder (the farthest cylinder from the flywheel) from the nearest to the flywheel crank journal.

• If the angular twist of the crankshaft is Δθ when the fourth cylinder burns / expands, then:
  when the third cylinder burns / expands the angular twist is 3*Δθ (because between the nearest to the flywheel crank journal and the crankpin of the third cylinder there are three crankshaft pieces like a: the a, the b and the c),
  when the second cylinder burns / expands the angular twist is 5*Δθ (similar reasoning as before),
  and when the first cylinder burns / expands the angular twist is 7*Δθ.

I.e. while the combustion pulses happen per 180 crank-degrees, the twisting of the crankshaft (measured at its complete length) maximizes per 720 crank degrees and so it is of half order.

At low revs the inertia torque is small relative to the combustion pulses, so the PatVRA and the conventional load their crankshafts equally.
At high revs the inertia torque is the dominant load on the crankshaft of the conventional plane-crankshaft I-4, while the PatVRA is loaded only by the combustion torque pulses.

So, the PatVRA can use a thinner (i.e. having smaller diameter crankpins and main journals) crankshaft without spoiling reliability.

• Among the advantages are:
  the more lightweight – yet reliable – crankshaft,
  the reduced friction (smaller diameter crankpin and journal bearings, no heavy idle loads reciprocating along the transmission),
  the quieter / smoother operation (only useful torque passes to the transmission),
  the springs on the clutch disk can be harder (or completely eliminated),
  the better feeling (how well the drive wheels/tires are hooked up), etc.

I think the following quotes are useful for those who want to get the difference the PatVRA brings.
In simple words, it has the advantages of the cross-plane crankshaft (Yamaha R1), and all the advantages of the plane crankshaft, without their drawbacks.



The following quote is from https://www.motorcycle.com/ask-mo-anyth ... shaft.html (October 2016) :

Here’s what Suzuki had to say in introducing the all-new GSX-R1000 last week, which uses the same 180-degree, or flat crank, it always has. Our lead photo shows the new GSX-R engine on the left and the outgoing one on the right; note that the baby bump on front of the old engine, where its small balance shaft used to live, is no more on the new engine.



Nearly all inline Fours use a flat crankshaft like this one (which doesn’t belong to the new GSX-R). Two pistons up + two pistons down = perfect primary balance.

“Suzuki engineers carefully considered using non-conventional, uneven-firing-order crankshaft phasing versus the GSX-R’s traditional even-firing-order crankshaft phasing.
“The theoretical advantages of uneven firing order can apply in MotoGP racing, where engine output exceeds 230 horsepower and the biggest obstacle to turning good lap times is cornering traction and the rider’s ability to feel how well the rear tire is hooked up at any given throttle opening. But there are very real inherent engineering challenges that must be overcome with an uneven firing order. It’s more difficult to produce strong power and torque with an uneven firing order, especially at low rpm and in the midrange. Vibration is increased, requiring much thicker and heavier crankcases and a counterbalancing shaft, and associated mechanical losses contribute to overheating.



Yamaha’s Crossplane crank needs to spin this large balance shaft (part #14 on BikeBandit’s fiche) to quell its vibes; Suzuki’s new GSX-R1000 does away with the small balance shaft it used last year, joining other balance-shaft-free inline Fours like the BMW S1000RR, Honda CBR1000RR and others.

“The big question Suzuki engineers faced was whether or not, for a production motorcycle, the theoretical advantages of an uneven firing order design outweighed the inherent complications. Including the fact that solving the problem of making strong power with an uneven firing order while controlling vibration, heat and weight gain would make the motorcycle more expensive, significantly increasing the retail price.
“With testing, the engineers found that they could enhance traction and feel with a superb chassis design and effective electronics. And they decided that the even-firing-order, screamer engine sounded better, too.”
Ouch.
There you have it. We love the texture of the R1 big-bang engine and how it sounds, but time will tell if its added complexity eventually might go the way of the five-valve head.



An analysis of the “crossplane vs flat-crank” is at https://mecaniblog.wordpress.com/2016/0 ... -approach/ wherefrom the following plot is:



The torque delivery is smoother at the crossplane option, although the mean torque is the same for the two options (that means the same power). The main advantage of the crossplane configuration, is that deliverying the power more smoothly, the rear tire is able to stand more time in good conditions, and that is so important when we speak about racing.



Quote from https://www.motoroids.com/features/tech ... rankshaft/ :





The cure is a crankshaft with pistons at 90 degree intervals as opposed to 180 degrees of a flat-plane crankshaft and an irregular firing pattern. The inertia torque is reduced to almost zero before 10,000rpm and crucially, to only about 3% of the flat-plane crankshaft value at 15,000rpm. This means that the rear tyre will mimic the inputs of the throttle giving excellent feel which has been much appreciated and praised by riders all over the world.

SO WHAT’S THE DOWNSIDE?

Of course the law of physics state that you never get something for nothing and an irregular firing order means more vibrations that may require a balance shaft or heavier components to tame, thus losing you part of quick response that you have gained.

WHAT CAN BE BETTER THAN THE CROSS PLANE CRANKSHAFT?

Honda thinks it’s going to be the V4. In principle what the cross-plane crankshaft essentially does is that it mimics the working of a 90 degree V4 in the inline-4. But a V4 won’t be as compact as an inline 4, at least in theory with the bike losing out on shorter and therefore more nimble machine. Yamaha swear by their tech and will stick with inline-4. But you never know, Honda might just pull it off.

Thanks
Manolis Pattakos

[Rodak]

....manolis, with his pictures of castings, etc. has no intention of actually building and strapping (or gluing, you choose) this contraption to his torso and starting the engine. It's all a giant word salad ®.

Manolis, I'm curious what your response is to my statement. Do you actually plan to build a 'flyer' and what is your schedule, or is this all bullshit?

[uniflow]

....manolis, with his pictures of castings, etc. has no intention of actually building and strapping (or gluing, you choose) this contraption to his torso and starting the engine. It's all a giant word salad ®.

Manolis, I'm curious what your response is to my statement. Do you actually plan to build a 'flyer' and what is your schedule, or is this all bullshit?

I think its just about securing investors.

[manolis]

Hello Rodak

You write:
"Manolis, . . . Do you actually plan to build a 'flyer' and what is your schedule"


I am building it.
And the schedule is "one step at a time".

Thanks
Manolis Pattakos

[Rodak]

And step one might be exactly.... what? You've been leading us on, pretending you were actually trying to make a flying machine; I say bad boy.

[uniflow]

manolis, what of the 'big bang' 500 four cylinder GP twostroke engines where all combustions take place over 60 degrees of crank rotation.
Or the parallel twin twostrokes where the cranks are at 90 degrees, like a v twin would be.
These engines won GP races, there is a very good reason for this.

[J.A.W.]

manolis, what of the 'big bang' 500 four cylinder GP twostroke engines where all combustions take place over 60 degrees of crank rotation.
Or the parallel twin twostrokes where the cranks are at 90 degrees, like a v twin would be.
These engines won GP races, there is a very good reason for this.

1stly Uniflow, congrats on your TPI success, you fully deserve it, (& the right to heap shame on KTM),
but please, do let us know if/when the promised TM arrives!

However, back on the topic of 'big bang' 2T GP bikes..

Actually, these machines proved more trouble than they were worth, not least in terms of their
abrupt torque pulses damaging existing transmission components (thus requiring ++ redesign),
& ultimately then being abandoned when tyre technology caught up with 'screamer' power.

As for the KTM parallel-twin running a 90' crank-pin arrangement, best ask your (highly experienced
with racing 2T-tech) fellow Kiwi, 'Wobbly' - how an attempt to run that configuration in a race-tuned
parallel-twin RZ Yamaha - worked out for him. He'll provide "a very good reason", why it didn't...