Ratatouille wrote:The 2-stroke vrs. 4-stroke dilemma was pretty much settled in the early 2000's MotoGP. IIRC 2-stroke engines were allowed up to 1000cc and 4-stroke engines up to 500cc.
I remember the Pons Honda from Alex Barros using 2-stroke with higher CC's, while other teams including official Honda team using 4-stroke engines.
It was shown back then that the 2-stroke cylinders had much better torque but the 4-stroke offered much better power curve and above all driveability and top end speed.
you have that backwards. the 2 strokes were 500s the 4 strokes were 900s
990 cc to be nitpicking
Yeah, & 2Ts were also hurriedly banned by the FIM, for Moto GP, esp' once they dropped to 800cc,
since the smaller 2T classes had kept gaining power under development, up to ~440hp/litre!
"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).
I did not realize you were doing the order of 2T engines in the order more like a theoretician rather than an experimentalist (to borrow the Physics terms). I think if you are moving from your domain of expertise, and as you nicely explained it, in patenting an engine you write it up and patent it before ever really testing it practically, then I think those with flight experience (uniflo, autogyro, others on other forums I saw you on) would suggest that you prioritize actual progressive flight testing. It's easier for a flying craft to kill you than an engine on a bench. This seems like an uncontroversial point???
So we do have a simple case to examine and use it as the basis for the full analysis of the Portable Flyer Control: it is the “frozen astronaut that recovers from a vertical dive” and has full control over his flight even by moving only his tongue (I imagine the “clever” comments, however this is the truth: a “paralyzed” astronaut can control his flight by just moving his tongue; this is what the maths and physics predict, and, as a wise man said: “nobody can argue with mathematics”).
It's very funny, because I use 'pissing off the side of a cruise ship to turn it' as a reason to do *more* analysis and testing, and you seem to use the same example 'an astronaut can fly by moving his tongue' to do none!
I think that is the fundamental disagreement here. I don't think it is solvable and I don't think you will every understand or take our advice on this matter. Evidence (and I have now read every page of this thread and the other ones you archived on your website) suggests you never (literally, I could not find a single example) take on board suggestions or advice from forum members.
Please don't misunderstand me again - I absolutely get your little examples about birds and tongues and ladies in the bed - they however do not convey any useful information in a dynamic flight context (from my flight control systems experience). (same with pendulum rocket fallacy btw)
It is not that this 'pissing off the side of a cruise ship to turn it' / 'astronaut tongue control' is not trivially and obviously true - it 100% is and that is why everyone understands the pissing analogy, it is just that it is such a minor and misleading point with respect to the controllability and stability of flight craft. By the way, this was part of Rodak's point also about having it both ways - the PF is so controllable a small hand motion turns it, yet so stable there isnt risk of instability / the human brain will save it.
This is also my point about the flight envelope and the singular point we try to stay on wrt. transition from hover to horizontal flight - if can you transition from hover to horizontal flight using your 'tounge' or 'moving your foot / c.g. 1cm forwards' then how long does that take, and is that a controllable and stable mode when you want to transition from horizontal flight to hover!
(also, your definition of controlability is not strictly speaking the control systems engineering definition of it, but whatever at this point I guess)
Finally, you seem willing to say you are confident because "physical laws say so". Those physical laws also govern the fields of control and aeronautical engineering, fields which you are not as familiar, fields that some of use here are familiar with, and fields that say, as I have said many times, that you cannot say meaningful things about controllability and stability from static pictures.
You ask of others "good will". I ask of you the same.
I have read your posts here on other forums where others have said exactly what we say here about the steps required to understand the controllability and stability of flying craft. Your memory of these encounters is that "No-one can “see” some flaw. So far the project survived".
Another description of these encounters is that people more familiar with flight and control than you have explained repeatedly why your application of simple physical laws is not comprehensive enough. You have then refused this point and continued as though you were correct.
I don't know what else to say.
Last edited by nzjrs on 09 Oct 2020, 12:15, edited 2 times in total.
Hello Tommy Cookers.You write: "btw today's news to myself is that ......
a flat-crank 3 and conventional 3 would have about the same vibration"
The kind of their vibrations is substantially different.
The flat-crank 3 has a strong unbalanced inertia force, it also has a strange / asymmetrical inertia torque and uneven firing.
The conventional 3 has a strong unbalanced inertia moment (for the rest, it is near perfect).
Things get worse for the flat crank 3 in case they are two-stroke engines:
The two-stroke flat crank 3 fires per 180 crank degrees, with the one cylinder firing alone and with the other two cylinders firing simultaniously (and giving a two times stronger power pulse). The feeling will be close to a single cylinder.
The conventional 3 two-stroke has equal combustion pulses per 120 crank degrees.
With its lower inertia torque and the even and evenly spaced combustions, it gives the sense of turbine.
To "have about the same vibration", as you write, is not reasonable.Thanks
Manolis Pattakos
the flat-crank Laverda 3 had only c.33% of the primary vibration that a 1000cc single or twin equivalent would have
(remember Laverda already had popular equivalent 360 deg 750cc twin - solid-mounted and no counterbalance shafts !)
with 'sloper' engine part-replacing the frame - a very stiff path minimising vibration (after NSU Max, Honda Dream, Panther etc)
and USA rules on mirrors made rubber-mounted handlebars universal by 1970 - helping the worst-vibrating machines most
to MP
I thank you for your post P233 giving calculated results for comparison ..... and fwiw .....
broadly I accept these though there's only loose agreement with my methods (so far) .... however .....
differences in combustion-related torque and particularly the inertia torque are imperceptible to the road vehicle user
because the load is dynamically isolated from the engine by the transmission 'shock absorber', tyre, etc etc
(ok in a gyrocopter the load (propeller) isn't isolated from the engine - why uniflow's flat-crank 3 plan caught my attention)
the conventional-crank 3 was extensively tried in motorcycles but has faded away
the frames had low 'impedance' to vibrating moments so IMO amplified vibration relative to that the 'numbers' suggested
frames and particularly handlebars and footrests are net amplifiers not attenuators
probably the reason that most conventional 3s had rubber mounting (none chose moment counterbalance shafts)
a conventional chain drive motorcycle can't have 'full isolation' mounting - or the chain will fall off at maximum acceleration
'partial isolation' (natural frequency at/above idle rpm) was ok as the damping coefficient was high to prevent resonance
('full isolation' - soft/low damping/natural frequency+resonance below idle rpm gives best vibration attenuation above idle)
I flew a gyrocopter with a conventional 3 (75 bhp Arrow ?) - there was no apparent vibration problem
no I didn't consider the structural impedance
crankshaft torsion (maybe torque delivery) and prop blade vibration are related - though composite props alleviate this
so rubber engine mounting or prop isolation are non-trivial matters
RETRO-EDIT
yes as JAW says I have failed to mention the resurgence of counterbalance-shaft 3s (Triumph Yamaha MV)
Last edited by Tommy Cookers on 09 Oct 2020, 21:23, edited 3 times in total.
Hello Tommy Cookers.You write: "btw today's news to myself is that ......
a flat-crank 3 and conventional 3 would have about the same vibration"
The kind of their vibrations is substantially different.
The flat-crank 3 has a strong unbalanced inertia force, it also has a strange / asymmetrical inertia torque and uneven firing.
The conventional 3 has a strong unbalanced inertia moment (for the rest, it is near perfect).
Things get worse for the flat crank 3 in case they are two-stroke engines:
The two-stroke flat crank 3 fires per 180 crank degrees, with the one cylinder firing alone and with the other two cylinders firing simultaniously (and giving a two times stronger power pulse). The feeling will be close to a single cylinder.
The conventional 3 two-stroke has equal combustion pulses per 120 crank degrees.
With its lower inertia torque and the even and evenly spaced combustions, it gives the sense of turbine.
To "have about the same vibration", as you write, is not reasonable.Thanks
Manolis Pattakos
to MP
I thank you for your post P233 giving calculated results for comparison ..... and fwiw .....
broadly I accept these though there's only loose agreement with my methods (so far) .... however .....
the differences in combustion-related torque and particularly the inertia torque are imperceptible to the operator
because the load (road vehicle) is dynamically isolated from the engine by the transmission 'shock absorber', tyre, etc etc
(ok in a gyrocopter the load (propeller) isn't isolated from the engine - that's why uniflow's flat-crank 3 caught my attention)
the conventional-crank 3 was extensively tried in motorcycles but has faded away
the frames had low 'impedance' to vibrating moments so IMO amplified vibration relative to that the 'numbers' suggested
probably the reason that most conventional 3s had rubber mounting (none chose moment counterbalance shafts)
a conventional chain drive motorcycle can't have 'full isolation' mounting - or the chain will fall off at maximum acceleration
isolation via natural frequency within running rpm range was ok as the damping coefficient was high to prevent resonance
I flew a gyrocopter with a conventional 3 (75 bhp Arrow ?) - there was no apparent vibration problem
no I didn't consider the structural impedance
T-C, FYI...
Norton's Commando 'Isolastic' system was successful enough to be reiterated by Harley-Davidson,
& while no large multi-cylinder/capacity 2T motorcycles have been marketed in recent years,
rougher 4T (in firing-interval terms) "conventional" 120` triples are sold by Triumph/Yamaha/MV...
"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).
You write: “I did not realize you were doing the order of 2T engines in the order more like a theoretician rather than an experimentalist (to borrow the Physics terms). I think if you are moving from your domain of expertise, and as you nicely explained it, in patenting an engine you write it up and patent it before ever really testing it practically, then I think those with flight experience (uniflo, autogyro, others on other forums I saw you on) would suggest that you prioritize actual progressive flight testing. It's easier for a flying craft to kill you than an engine on a bench. This seems like an uncontroversial point???”
Another reading of the above is:
The core ideas of the pattakon projects are so right / solid / correct, that the experiments / the testing just confirmed the theory.
For the PatVRA, for instance:
it was calculated theoretically the inertia torque using the pattakon balance program.
And the inertia (or idling) torque was so strong that it was a problem.
The invention solves this problem by preventing the inertia torque from passing to the transmission.
I didn’t know if the PatVRA or some similar idea was already proposed. According the Search Report of the UK Patent Office, it was not.
So, based exclusively on theory and calculations, the problem was analyzed and solved. Practically nothing (nothing at all) has been done to test the PatVRA.
Yet the solution is good because not only solves the problem, but it is also simple, strong, compact, cheap and easily applicable.
An engineer should be able to easily see it.
See the clever question of Gruntguru; I had to put some numbers to show there is no problem.
Some engine experts find a different solution to the same problem: they sacrificed the even firing, they also added an external balance shaft, they also compromise with the tune exhaust (the invention and patent started by Kawasaki, the application was done several years later by Yamaha with their R1, the permanent winner for several years of the motoGP).
An engineer can compare the two solutions. Without making models.
The theory comes first, and only if the theory says so, parts have to be manufactured for tests.
THREE CYLINDER VUIBRATIONS
See how straightly Tommy Cookers asked about the vibrations of the flat crank three cylinder as compared to the conventional three: “I want something more than feeling and similar nonsense”.
According your approach, someone expert should make a series of models to see, in practice, their vibrations.
Another approach is the theory:
My practical experience with three cylinder engines: a couple of decades ago I drove for some hours a rent OPEL car powered by a three cylinder engine.
Pattakon VVA’s
The pattakon VVA’s were, initially, theoretical designs.
Later they were made proof of concept prototypes and confirmed on the road what the theory predicted. Everything worked better than expected (the following is a test run on the road of a 1600cc four cylinder Honda VTEC car modified to pattakon-VVA-roller) :
In the International Engine Expo of 2008, Stuttgart Germany, a guy (former world champion, as he said, and manufacturer of 2-stroke racing engines and motorcycles) was playing with this handmade poor-quality DVVA prototype:
as a boy plays with his new toy. He was happy because he saw the solution of the problem, he was miserable – at the same time – because despite he tried to find a similar solution for decades, he failed.
PatVVD
Almost the same mechanism of the PatVRA is used for the PatVVD:
a continuously variable valve duration system that competes the CVVD of Rover/Hyundai.
No working prototype has been done so far.
So, so far it is just “thin air”.
Yet I am sure it works.
You doubt? Let’s bet to make it more interesting.
LONG EXPERIENCED vs OUTSIDERS
For those having long experience in making something (engines? airplanes? helicopters? . . .) it is more difficult to “think out of the box”.
The “outsider” has the luxury to doubt about everything, has also the advantage of the “fresh look” (clear eye) on everything.
ASTRONAUT RECOVERY FROM VERTICAL DIVE, again
As for the astronaut and his control, it would be the beginning for the explanation of the Portable Flyer control.
When the astronaut uses only his tongue to control his flight, obviously the control will be slow, yet it will be a full control; the astronaut can adjust his speed to be so slow that the corrections made with his tongue to be adequate, say to avoid an obstacle, or to land vertically, or to take off vertically, or . . .
Yet, it takes some “good will” to follow the reasoning and get the way the Portable Flyer is to be controlled.
In another post I will explain it by numbers for those who are interested to listen.
Yet, it takes some “good will” to follow the reasoning and get the way the Portable Flyer is to be controlled.
Honest question, do you really think people don't understand the tongue / pissing theory out of a lack of good will? Or what's going on here do you think?
nz, you're a paragon of virtue with your tack and etc. I thought for a bit about building a model flyer with a large doll for the pilot and do a bit of experimenting, but since manolis refuses to provide basic information re weight, c.g., dimensions, etc. gave it up.
Really manolis, if you won't even tell use where the c.g. is how can we even start to evaluate the control system? The location of the c.g. and the center of pressure determines whether the flyer is stable or not. Pretty basic stuff.
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 . . .
.
