Engine rev flutter sound on upshifts

[toto1041]

Why do the engines from this season sound like they flutter right after an upshift? the rev flutter seems to be more pronounced with gears 4-7. I think the Ferrari engine displays the most obvious example of this.

[autogyro]

Why do the engines from this season sound like they flutter right after an upshift? the rev flutter seems to be more pronounced with gears 4-7. I think the Ferrari engine displays the most obvious example of this.

Shows how non seamless the gearbox is.

[ISLAMATRON]

autogyro, you do understand that the rules require the gearboxes to not be seamless? The teams have already created truely seamless gearboxes and the FIA have already deemed them illegal.

I too wonder about the destinctive flutter, IS it an aural "illusion"?, clutch slipping slightly? blip of throttle by the ECU to help save the gearbox? or maybe something else

[autogyro]

autogyro, you do understand that the rules require the gearboxes to not be seamless? The teams have already created truely seamless gearboxes and the FIA have already deemed them illegal.

I too wonder about the destinctive flutter, IS it an aural "illusion"?, clutch slipping slightly? blip of throttle by the ECU to help save the gearbox? or maybe something else

I am well aware that the gearbox regulations go a long way in defining a layshaft gearbox on two shafts. However I have been unable to find a distinct reference to 'seamless' transmissions.
The term 'seamless' is not technically correct and my own experience of the term has been confined to the manufacture of trousers.
The flutter is because of the 'gap' between gears that requires the EMS to reduce torque during the change. It may be as fast as 4ms but it has a longer and 'obvious' effect on other aspects of the performance envelope.
I will concede to Islamatron the possibility of unusual acoustics (from hot air perhaps). The promo guys use loads of that.

[RH1300S]

autogyro - why do you hijack every thread to talk about your gearbox. I'm sure it's fascinating - but keep it in one place PLEASE [-o<

Back OT - toto1041, I hear this too - it sounds to my ear as if the driver has run the engine against the rev limiter and has shifted a fraction too late. I find it hard to believe that's the case, because (as you say) it's a consistent feature particularily with the Ferrari (although it's evident with other cars too).

Not a helpful answer - but I'm confused by that one too.

Personally I don't think the flutter sound has anything to do with the transmission changing gears - you hear the gearchange steps clearly enough in the lower ratios.

If you listen what you hear is the revs rising to the point where you expect the driver to change gear - there seems to be a delay for a short time where the revs appear not to increase THEN the gearchange is selected by the driver. As if he has changed gear too late.

Probably something odd with the sound transmission. It would be interesting to compare an exterior sound track with on on-board one.

[xxChrisxx]

The flutter is most likey from the higher gear that is engaged overdriving the lower gear. That's my semi educated guess. There is acutally no time between shifts where 0% power is going to the drive wheels, its just not 100% power.

Zeroshift boxes are in 2 gears at once for a fraction of a second.

[autogyro]

The flutter is most likey from the higher gear that is engaged overdriving the lower gear. That's my semi educated guess. There is acutally no time between shifts where 0% power is going to the drive wheels, its just not 100% power.

Zeroshift boxes are in 2 gears at once for a fraction of a second.

NO they are not!
If you did that you would blow the gearbox into little pieces!
Twin shaft/clutch boxes can almost do it subject to clutch slip, they suffer from higher torque loss, larger size and complication.

[xxChrisxx]

The flutter is most likey from the higher gear that is engaged overdriving the lower gear. That's my semi educated guess. There is acutally no time between shifts where 0% power is going to the drive wheels, its just not 100% power.

Zeroshift boxes are in 2 gears at once for a fraction of a second.

NO they are not!
If you did that you would blow the gearbox into little pieces!
Twin shaft/clutch boxes can almost do it subject to clutch slip, they suffer from higher torque loss, larger size and complication.

Are they using Zeroshift technology or two clutches? I thought F1 were using single clutch zeroshift.

Just been reading up on the regs, they can't use 2 cluteches for the very reason they they can set it to slip. This creating a pseudo-CVT box. A second seperate clutch is allowed for KERS only.

So that kind of decides it, F1 is using some varient of a single clutch seamless shift.

EDIT: And no being in two gears at once wouldnt blow the gearbox if you are using the sliding dogs in a zeroshift box.

[autogyro]

The flutter is most likey from the higher gear that is engaged overdriving the lower gear. That's my semi educated guess. There is acutally no time between shifts where 0% power is going to the drive wheels, its just not 100% power.

Zeroshift boxes are in 2 gears at once for a fraction of a second.

NO they are not!
If you did that you would blow the gearbox into little pieces!
Twin shaft/clutch boxes can almost do it subject to clutch slip, they suffer from higher torque loss, larger size and complication.

Are they using Zeroshift technology or two clutches? I thought F1 were using single clutch zeroshift.

EDIT: And no being in two gears at once wouldnt blow the gearbox if you are using the sliding dogs in a zeroshift box.

You can try selling zeroshift as much as you like but it will still remain a method to speed up the shift and NOT allow two gears to engaged at once no matter what the marketing guys try to convince you of.
I was simply explaining that a twin shaft/clutch gearbox can get faster on the gearchange by engaging one gear as it disengages the other, each on different clutches. It also cannot have two gears engaged at the same time. Such a condition on any stepped box, results in locking up the geartrain and if done at high revs/torque input will bloww the unit into pieces. I have done it a number of times, I wonder if anyone else on here has? A twin shaft gearbox could be used in F1 so long as it worked sequentially. There is no point however as such units drain torque are to heavy and bulky and over complicated.

[xxChrisxx]

You can try selling zeroshift as much as you like but it will still remain a method to speed up the shift and NOT allow two gears to engaged at once no matter what the marketing guys try to convince you of.
I was simply explaining that a twin shaft/clutch gearbox can get faster on the gearchange by engaging one gear as it disengages the other, each on different clutches. It also cannot have two gears engaged at the same time. Such a condition on any stepped box, results in locking up the geartrain and if done at high revs/torque input will bloww the unit into pieces. I have done it a number of times, I wonder if anyone else on here has? A twin shaft gearbox could be used in F1 so long as it worked sequentially. There is no point however as such units drain torque are to heavy and bulky and over complicated.

I remember reading about this a couple of years ago. Zero shift is more simple and far more clever than 2 clutches.

You are several years out of date.

It has 6 sliding dogs, 3 for accelration and 3 for deceleration. They are designed to lock in 1 direction only, and use a spring system to disengage the free dogs.

When you select an upshift the 3 unloaded dogs move to select the gear above, this then partially engages the gear which overdrives the lower one. The dogs are chamfered on 1 side to allow them to slip when overdriven.

This overdrive then unloads the remaining 3 dogs engaged on the 1st gear and allows them to then shifto the 2nd. Fully completeing a gearchage without losing drive, engaging 2 gears at once, but having the dogs unload as it does so.

Very elegant.

[autogyro]

Indeed very elegany but NOT two gears engaged at the same time!!!!!!!!!!!!!

[xxChrisxx]

Indeed very elegany but NOT two gears engaged at the same time!!!!!!!!!!!!!

Fine i'll find you the bloody link.

The second gear unloads the first... so for an instant in time, you are twchnically in two gears at once. Two gears arent doing the driving however. That's WHY it's called zero shift.
Once drives, the INSTANT second enganges and takes over the drive unloading the first and then fully engaging second.

[autogyro]

Oh yes and you are 70 years out of date.
The Wison pre-selector box fitted to the ERA in the 1930's had an 'overlapping' shift closer in component engagement than any so called modern 'seamless' gearbox.
The gains of around 4ms from any of these modern systems is hardly worth bothering with, they still disrupt the smooth flow of torque, which still has to be varied to accommodate their operation.

[autogyro]

Indeed very elegany but NOT two gears engaged at the same time!!!!!!!!!!!!!

Fine i'll find you the bloody link.

The second gear unloads the first... so for an instant in time, you are twchnically in two gears at once. Two gears arent doing the driving however. That's WHY it's called zero shift.
Once drives, the INSTANT second enganges and takes over the drive unloading the first and then fully engaging second.

Find the link, quote the marketing bumf, pray to Alah if you like, it is still not allowing two gears to be engaged at the same time.
You are NOT technically in two gears at once.

[xxChrisxx]

http://www.zeroshift.com/pdf/RcarN6V15_Zeroshift.pdf

Racecar Engineering article about it.

http://www.zeroshift.com/animation.html

Lovely animations about how it works.


This is NOT preseletion as used in the 30's using a billion clutches and epicyclic (I even had to read up on this just now as its so antiquated i'd never heard of it). This is the most likely current method of F1 seamless shift.