MotoGP Aero.....

[variante]

I don't think stability/driver confidence would be an issue.

After a fast calculation, given a leaning angle of 45° (kind of the ideal one for such system) and speed of 150km/h, the net cornering gain from the system shown above would be around 1.5%. Not much unfortunately. And not enough for the rider to be worried about, at least.

Although the gain could be further increased, it wouldn't be easy at all to overcome the previously mentioned issues this system would face... That's the real problem.

[hollus]

when producing 230 hp motorcycles will tend to be front end light even in top gear ? (ie at full speed)

DF of the kind envisaged will benefit cornering grip whenever the bike lean angle is less than the rider lean angle
and when the bike is cornering fast in an oversteering attitude there's some helpful 'whole-body' aero force from the -AoA effect
ie a downward component and a (centripetal) component helping the turn

presumably the rules prevent more extensive development of aero forces ?

Bolding is mine. If you look at the picture below, it is clear that the angle in which downforce is being applied is somewhat more "vertical" then the angle between contact patch and center of mass, so there might be quite some benefit while cornering. (Am I missing something here?)

But there could also be significant benefits when in a straight line. With downforce so much to the front, it should allow for more acceleration without a wheelie; but it should also help significantly when braking, which for MotoGP takes quite a loooooong time before much lean angle is applied at all. The front wheel should get a significant extra load at no cost to the rear wheel.

[Jolle]

when producing 230 hp motorcycles will tend to be front end light even in top gear ? (ie at full speed)

DF of the kind envisaged will benefit cornering grip whenever the bike lean angle is less than the rider lean angle
and when the bike is cornering fast in an oversteering attitude there's some helpful 'whole-body' aero force from the -AoA effect
ie a downward component and a (centripetal) component helping the turn

presumably the rules prevent more extensive development of aero forces ?

Bolding is mine. If you look at the picture below, it is clear that the angle in which downforce is being applied is somewhat more "vertical" then the angle between contact patch and center of mass, so there might be quite some benefit while cornering. (Am I missing something here?)
https://cdn.rideapart.com/wp-content/up ... 70x433.jpg
But there could also be significant benefits when in a straight line. With downforce so much to the front, it should allow for more acceleration without a wheelie; but it should also help significantly when braking, which for MotoGP takes quite a loooooong time before much lean angle is applied at all. The front wheel should get a significant extra load at no cost to the rear wheel.

I presume that at those lean angles, which are at relative slow speed, the negative effect of the aero force (you can't call it downforce at that point anymore) is very small. The drag would almost counterbalance it, making the bike turn even more.

What for instance Marquez's technique, what makes him so good, that he puts the bike (not himself) upright in a 30 degree angle (when the aero force becomes down force) already into the corner, to have the best contact patch on the back wheel.

A MotoGP bike acceleration is limited by the COG, what gives it around a 1G acceleration. Yamaha even counterrotates the crank to get a few more % out of it. So.... just a few kg of downforce, brining the COG forward a couple of cm, from around 120kph makes a big difference. The COG has to be around the middle to make it corner fast, in low speed corners. Low speed corners are so slow that aero force is minimum.

[J.A.W.]

Funny how fashions go 'round.. the Heron-Suzuki GP bikes of the late `70's also used those winglet-type aero-strakes..

& even a regular showroom production road bike from the last century can better a 1G acceleration rate..
( Viz: Cycle World magazine tested a Suzuki GSX-R 1300 back in 1999, & recorded a 0-60 mph time of 2.6 secs).

If some actual Moto GP telemetry figures could be found, they'd of course show it - as significantly higher G forces.
While the electronic launch control settings of each rider is likely regarded as 'restricted' - info.
..yet the acceleration G - as physics numbers - can be derived from time-to-speed data, fairly readily..

[bdr529]

That is funny you mentioned the Suzuki, I was clean up some picture files over the weekend and came across these two photo's
don't know why I never notice the winglets on the Suzuki till now, I have this photo in a couple of different files

1979 Suzuki RG500 Barry Sheene


1977 Rodger Freeth Aerofoil Viko TZ-750A


this one I don't remember much about it, I think it's was from Australia and it never raced because other riders were worried about getting tangled up in the rear wing, I could be wrong I haven't seen this pic in like 15 years

edit: found another pic

[J.A.W.]

Yeah ta bdr...

Pat Hennen tried those winglets out, so team mate Barry Sheene had to have them too,
- but they were later shelved, after Pat left the team after a serious I.o.M. crash ( But not due to the aero-effects, AFAIR).

Dr Rodger Freeth was a Kiwi physics prof, as well as a notable biker racer.
& he tried out 'wings' that were attached to his TZ 750 both to the sprung chassis & direct to un-sprung suspension/wheels..

Of course it was promptly banned from racing, & for showing innovation, as much as any increased 'danger' - real, or otherwise..

[Cold Fussion]

Perhaps you could have some sort of ground effect mounted at an angle on the side of the bike that is only active when the bike leans in and the tunnels gets closer to the floor?

Exactly! That's the only way you could achieve any improvement while cornering at an angle of 45° or beyond.

I was thinking of something like this:
http://i1372.photobucket.com/albums/ag3 ... v4jmmw.png
http://i1372.photobucket.com/albums/ag3 ... x3byca.png
The positive gain of the wing in ground effect would overcome the "centrifugal" effect of the other one.
Still, such system would face many issues... Kerbs, excessive angles, low efficiency,...

On the Ducati, those wings become useful if the typical cornering angle is smaller than 45°, or under braking (in certain conditions only); they also make wheelies less probable, as turbo said. As for the vortices...possibly.

Wouldn't the blockage caused by the rider leaning off the bike cause it to very inefficient/not work well at all?

[variante]

Perhaps you could have some sort of ground effect mounted at an angle on the side of the bike that is only active when the bike leans in and the tunnels gets closer to the floor?

Exactly! That's the only way you could achieve any improvement while cornering at an angle of 45° or beyond.

I was thinking of something like this:
http://i1372.photobucket.com/albums/ag3 ... v4jmmw.png
http://i1372.photobucket.com/albums/ag3 ... x3byca.png
The positive gain of the wing in ground effect would overcome the "centrifugal" effect of the other one.
Still, such system would face many issues... Kerbs, excessive angles, low efficiency,...

On the Ducati, those wings become useful if the typical cornering angle is smaller than 45°, or under braking (in certain conditions only); they also make wheelies less probable, as turbo said. As for the vortices...possibly.

Wouldn't the blockage caused by the rider leaning off the bike cause it to very inefficient/not work well at all?

Sure it would! ...and unfortunately that's not even the only problem, as previously mentioned.
However, there may be some favorable riding conditions where blockage would be negligible, and so all the other problems.
Which aspect -positive or negative- would prevail, i don't know.

[bdr529]

If the " winglets" purpose was to create down force in the corners, Would it not be more beneficial to have them set at a 45 deg angle or more depending upon the circuit ???

[variante]

Unfortunately not: with the bike leaning, you'd have one winglet pushing downwards (good) and one pushing outwards (bad)

[bdr529]

How does this differ from what you purposed earlier on page 1 ???

The positive gain of the wing in ground effect would overcome the "centrifugal" effect of the other one.

Why does this apply to the bike on the left and not the one on the right

[RicME85]

I'd assume because the placement is different, Variante's proposal has one airfoil working in ground effect, producing more downforce than the other proposal. As the comment you quoted said, the airfoil in ground effect would be working better than the vertical airfoil and counter its effect.

[wesley123]

Unfortunately not: with the bike leaning, you'd have one winglet pushing downwards (good) and one pushing outwards (bad)

You'll also have the horizontal winglet pushing on the lean angle, I'm not sure what effect that would have.

[matt21]

IMO the wings on the Ducati are more aiming to gain stability at high speed to stop fluttering.
To create downforce in a corner for me is only reasonable, if the force vector is running in the yaw axis to avoid any instability.

[J.A.W.]

Casey Stoner was recently interviewed on his return to the Ducati Moto GP team,
& asked for his test impressions - he made remarks on the smoothly integrated high-speed aerodynamics,
with significantly less buffet apparent compared to the ( minimalist approach) Honda fairing.

Yamaha have recently used aero-strakes on the fairing front of their Moto GP machines, but Honda appears to eschew such devices.
It will be interesting to see if the reputed lessening of front grip available from the new Michelin spec tyres causes a re-think there.