F1technical.net

Tommy Cookers wrote: ↑

21 Apr 2017, 14:31

big bang is a silly myth if people see BB as some magic beans boosting traction in car or bike GPs

because torque variations at the crankshaft...

...people should remember all previous 2 strokes 4s had for practicality cylinder pairs firing simultaneously and kept them for 4 decades
eg Suzuki square 4s 60s-90s and Yam 60s & 80s-90s 'square Vs' & 70s inlines - nobody called them BB
and the (4 stroke) Honda NR500 had a 0 deg '2 pin' crank - but nobody called that BB
(FW17 you can check the firing intervals of all these Honda 0 deg cranks ie whether 270/450 intervals or 90/630 intervals)...

T-C you might find Kevin Cameron's take on 'big-bang' to be of interest..

http://www.cycleworld.com/strange-tire- ... n-insights

Irregular firing impulses & crank angle configurations with disruptive inertial torque impulses can have unforeseen consequences in NVH,
& via 'shock loading' & 'chatter', cause subsequent fatigue failures, inc' for transmission & accessories..
..which - are a potential-probable cause for the issues McLaren-Honda currently contends with..

A case in point being..
..when R-R built a 'Chinese' copy of the Napier Sabre H-24 aero-engine, they
made some crucial changes, such as having the superimposed twin 180`V12-type crankshafts
run in opposite rotation, linked via a simple spur-type gear.. & with paired cylinders firing together..

..which caused repeated failures of the magneto shaft drive, due to the torsional harmonics..

The Sabre ran its similar crankshaft layout but rotating in the same direction, & phased 180`apart,
so no two cylinders fired together, & they were geared together via a more sophisticated compound balanced unit.. -
..& so avoided the damaging fatigue caused by harmonic 'chatter' - which plagued the ostensibly more simple (& traditionally functional, as used in their V12s ) R-R set-up..

Honestly i dont believe rumours in motorsport.it, unless they write it at motorsport.com. Wazari has stated that almost half of Sakura is on software and electrical focus. Their mapping is so complex, and their combustion is New, so there must be time lag until they can make their engine work in harmony. Andy Cowel stated that this engine is an orchestra, and the key to create good music is the module (software). This rumours is just spin off from Hasegawa information from test 'several thing' before benson wrote honda is trying New mapping or software. Its just normal activity to do so for honda, and also normal activity from journalist to sell story, unless they dont need money for eat.

@ J.A.W
what KC says to be the frequency of the torque ripple is roughly as I say, about 150 Hz
it should be a simple matter to see by measurement on a rolling road or similar whether this 150 Hz gets through the tyre to the road
how can it ?
and how would the rider not notice it ?
and wouldn't the effect be even more noticable on eg a 636cc Manx Norton ?

on any machine where snatching can be felt (when 'riding too slowly for the engine') the frequency is never more than maybe 3 Hz
bump a stationary bike around looking for a surge frequency - it's about 2 or 3 Hz
why ? - because the tyre cannot significantly transmit oscillations at higher frequencies - and that's why we have pneumatic tyres

if there is an effect it will be much smaller than KC's choice of words seems to imply
and whatever it is, it can be measured
amazingly ? nobody seems to have tried this
are the US flat tracks dominated by eg V twins modded to give the near-simultaneous firing for BB benefits (that has been tried) ?

anyway even if the BB Honda bike has none the F1 car has plenty of compliance in its transmission

godlameroso wrote: ↑

21 Apr 2017, 22:24

.

Sometimes people that have expertise in a specialized area can help resolve issues that are not apparent when working from a more holistic perspective.

Of course someone can see what someone cant not only because of experiment but Honda is also good on electric part.
Whatever, important thing is see Honda in a good place

Fires two cylinders at the same time is what gives you the advantage of better acceleration / power, I do not think that effect makes an improvement in the tire, the problem of that system is to make a crankshaft that supports those strokes and that is competitive / light. In the gif I only see a bike with suspension too hard wasting time in the curve.

Could it be that Honda is firing 2 cylinders at a time and that produces vibrations?

JuanjoTS wrote: ↑

22 Apr 2017, 10:37

Fires two cylinders at the same time is what gives you the advantage of better acceleration / power, I do not think that effect makes an improvement in the tire, the problem of that system is to make a crankshaft that supports those strokes and that is competitive / light. In the gif I only see a bike with suspension too hard wasting time in the curve.

Could it be that Honda is firing 2 cylinders at a time and that produces vibrations?

There was a long discussion of this back in the thread, started with wazari hinting about firing order, and glenn doing some audio analysis.

On that note it would be cool to compare audio from Bahrain race and Bahrain test.

Tommy Cookers wrote: ↑

22 Apr 2017, 02:28

@ J.A.W
what KC says to be the frequency of the torque ripple is roughly as I say, about 150 Hz
it should be a simple matter to see by measurement on a rolling road or similar whether this 150 Hz gets through the tyre to the road
how can it ?
and how would the rider not notice it ?
and wouldn't the effect be even more noticable on eg a 636cc Manx Norton ?

on any machine where snatching can be felt (when 'riding too slowly for the engine') the frequency is never more than maybe 3 Hz
bump a stationary bike around looking for a surge frequency - it's about 2 or 3 Hz
why ? - because the tyre cannot significantly transmit oscillations at higher frequencies - and that's why we have pneumatic tyres

if there is an effect it will be much smaller than KC's choice of words seems to imply
and whatever it is, it can be measured
amazingly ? nobody seems to have tried this
are the US flat tracks dominated by eg V twins modded to give the near-simultaneous firing for BB benefits (that has been tried) ?

anyway even if the BB Honda bike has none the F1 car has plenty of compliance in its transmission

At the risk of veering further off topic T-C..
..you noted the JAP speedway engine merits, well, its flat track equivalent in terms of decades-long success
was indeed a highly developed 45` H-D XR-750, & yes, all still with a 'knife & fork' conrod/single crankpin..
( so, yes, a type of 'natural' - 'big-bang', of sorts..)

nzjrs wrote: ↑

22 Apr 2017, 11:16

JuanjoTS wrote: ↑

22 Apr 2017, 10:37

Fires two cylinders at the same time is what gives you the advantage of better acceleration / power, I do not think that effect makes an improvement in the tire, the problem of that system is to make a crankshaft that supports those strokes and that is competitive / light. In the gif I only see a bike with suspension too hard wasting time in the curve.

Could it be that Honda is firing 2 cylinders at a time and that produces vibrations?

There was a long discussion of this back in the thread, started with wazari hinting about firing order, and glenn doing some audio analysis.

On that note it would be cool to compare audio from Bahrain race and Bahrain test.

Do you have / is there onboard footage from Mclaren qualy and fastest test laps?

[quote=J.A.W. post].........its flat track equivalent in terms of decades-long success was indeed a highly developed 45` H-D XR-750, & yes, all still with a 'knife & fork' conrod/single crankpin..
( so, yes, a type of 'natural' - 'big-bang', of sorts..)[/quote]

well, no ......
afaik the XR-750 of course has as standard firing intervals of 315 deg then 405 deg etc - so it is a natural (nearly) even-firing engine
to fit BB theory people would modify cams etc to get firing intervals of 45 deg then 675 deg etc ie more BB than the BB Honda
who does or has done this ?

similarly as has been said the F1 Honda could have a 0 deg 3 throw crank .......
and fire 3 cyls at the 270 deg interval then 3 at 450 deg later etc or fire 3 at the 90 deg then 3 at 630 deg later for real BB appeal
balance would be tolerably good, basically the same as a NA F1 style V8 and some expensive road cars

as has been said, when cylinder cutting the expected F1 engine firing intervals will be less even than when not cylinder cutting

GoranF1 wrote: ↑

22 Apr 2017, 17:40

Facts Only wrote: ↑

22 Apr 2017, 17:23

There's a difference between a rumour and just complete made up rubbish.

Yeah, but you are not the one that knows the differnce.

On this one i am, the great thing about a fact is that whether or not you believe it, it's still true. I i know for a fact that there isn't a roaming band of Merc engineers helping out Honda/Renault/Ferrari to boost the competition.

I wanted to know if the MGU-K can be used as McLaren's old extra brake pedal out of corners? It would help with traction and return a minuscule amount of energy too. I guess it is only possible if that braking can be controlled from left to right...? Oh yes, would it be legal too?

JonoNic wrote: ↑

22 Apr 2017, 19:51

I wanted to know if the MGU-K can be used as McLaren's old extra brake pedal out of corners? It would help with traction and return a minuscule amount of energy too. I guess it is only possible if that braking can be controlled from left to right...? Oh yes, would it be legal too?

https://youtu.be/zHWqGVxm4HU
https://youtu.be/W9ysHClUpQk

JuanjoTS wrote:

JonoNic wrote: ↑

22 Apr 2017, 19:51

I wanted to know if the MGU-K can be used as McLaren's old extra brake pedal out of corners? It would help with traction and return a minuscule amount of energy too. I guess it is only possible if that braking can be controlled from left to right...? Oh yes, would it be legal too?

https://youtu.be/zHWqGVxm4HU

Yes I watched that video and understand how it works. My question is using the stored energy as a form of traction control out of corners. Using the energy to slightly brake the inside rear wheel out of corners.

JonoNic wrote: ↑

22 Apr 2017, 21:03

JuanjoTS wrote:

JonoNic wrote: ↑

22 Apr 2017, 19:51

I wanted to know if the MGU-K can be used as McLaren's old extra brake pedal out of corners? It would help with traction and return a minuscule amount of energy too. I guess it is only possible if that braking can be controlled from left to right...? Oh yes, would it be legal too?

https://youtu.be/zHWqGVxm4HU

Yes I watched that video and understand how it works. My question is using the stored energy as a form of traction control out of corners. Using the energy to slightly brake the inside rear wheel out of corners.

It would be interesting what you propose because you could do without the differential, but I really do not think that works that way.

This is speculation and the moderator warned that it is not permissible in this thread, maybe there is a thread where we can comment this, but I do not know ... maybe the general thread of McHonda?