Ferrari F138

[Gilles 27]

I think ferrari's approach is slightly different from the McLaren - and perhaps more pertinently - the Sauber (because of the shared technology).

Ferrari have clearly gone for that very tightly-packaged, Williams-influenced rear end, and there's a big empty area behind the engine cover where previously there was bodywork.

It seems as if they're unable to have such small/undercut sidepods, possibly as a result of their other solutions, but there are other areas where they seem to have an advantage - seems to be more room for air under the nose and sloping down to the diffuser.

Time will tell which is better, but I'm sure Fry and co. have understood which works better with what they're attempting.

IMHO the hole black part of the sidepods / exaust could have massive evolution potential. The parts was made it intentionaly dark, to have difficulty to see some changes at first look. Even they don't have that small sidepods like Sauber/ RB the hole car design looks more accurate, any details of the car looks improved. I can't wait to see this monoposto on the track

[Hail22]

Scrabs first impressions of the F138:

[youtube]http://www.youtube.com/watch?v=PNRhCrCM8sU[/youtube]

[henra]

think of the bottom of the car as a converging diverging thermodynamic nozzle. the more mass y9ou get through it, the higher the expansion ratio the more efficient the nozzle and therefore the lower th pressure at the throat.
If the throat is the "kink" line where the flat botom ends and thre diffuser begins the higher the mass through there, the lower the pressure the higher the downforce from the underbody.

There is a trade off. More mass flow is good. But only if you can maintain the expansion ratio.
If the expansion is constant more mass flow could be achived at the price of less expansion. Depending on how the relation between mass flow and expansion ratio is you could have a net loss or gain.
Assuming that the overall expansion size is limited by diffuser regulation more mass flow under the ffloor will only be good if you can achieve more airflow over the floor as well, improving expansion ratio.
Therefore you want more air under the car but you will want to use most of it over the diffuser and only a small fraction under it to increase mass flow.

[munudeges]

Sam Michael's original explanation about why Williams went down their gearbox path was very ineresting, and coupled with the other facets of the Ferrari, is a good direction for them, I think.

The problem with Williams's gearbox is that they did absolutely nothing with that space when they got it. It was like they expected to miraculously gain performance just because they had opened up a large amount of space.

[PaulB]

[...]

Since 2009 Red Bull has used a fairing in different formats to cover the half shaft, the track rod (for adjusting toe angle) and half of the lower rear wishbone. The reason for this is that the rotation of the half shaft produces downforce because of the Magnus Effect, which is good. The problem is that when you introduce the exhaust plume into the equation, this effect becomes more unstable as exhaust flow is given out by the engine only on every exhaust stroke.
[...]

Are you sure? In my point of view, the rotating drive shaft produces lift.

[shelly]

Sam Michael's original explanation about why Williams went down their gearbox path was very ineresting, and coupled with the other facets of the Ferrari, is a good direction for them, I think.

The problem with Williams's gearbox is that they did absolutely nothing with that space when they got it. It was like they expected to miraculously gain performance just because they had opened up a large amount of space.

They could not exploit that space because of the bulky engine they got in 2011: with a more compact engine in 2012 the car was very fast

[shelly]

[...]

Since 2009 Red Bull has used a fairing in different formats to cover the half shaft, the track rod (for adjusting toe angle) and half of the lower rear wishbone. The reason for this is that the rotation of the half shaft produces downforce because of the Magnus Effect, which is good. The problem is that when you introduce the exhaust plume into the equation, this effect becomes more unstable as exhaust flow is given out by the engine only on every exhaust stroke.
[...]

Are you sure? In my point of view, the rotating drive shaft produces lift.

With flow form left to right in 2d, counterclockwise rotation of a cylinder would produce downforce on the isolated cylinder. In the driveshaft case, there are many interaction to take into account, and those probably result in a negative downforce effect, if every now and then Newey as soon as he can tries to put a shroud on the driveshaft (and all the others the next year, see for example byrne on the b195)

[amouzouris]

[...]

Since 2009 Red Bull has used a fairing in different formats to cover the half shaft, the track rod (for adjusting toe angle) and half of the lower rear wishbone. The reason for this is that the rotation of the half shaft produces downforce because of the Magnus Effect, which is good. The problem is that when you introduce the exhaust plume into the equation, this effect becomes more unstable as exhaust flow is given out by the engine only on every exhaust stroke.
[...]

Are you sure? In my point of view, the rotating drive shaft produces lift.

100% sure! the drive shaft is rotating forwards.. look at it this way..it is opposing flow over the top and accelerating flow at the bottom...air is slower at the top thus of higher pressure than the faster air at the bottom which of course has a lower pressure..and downforce is produced

[munudeges]

They could not exploit that space because of the bulky engine they got in 2011: with a more compact engine in 2012 the car was very fast

Hmmm, I beg to differ. They still had the space to work with that they opened up. The engine last year might have helped but aerodynamically the cars prior to Mike Coughlan's arrival were simply poor.

[amouzouris]

exactly, in isolation it should produce downforce.. im not sure if it produces +ve or -ve lift on the car itself but i am guessing that it produces -ve lift but it is too little because it is not in isolation and the disturbance it makes is not worth it

[Red Schneider]

My understanding of the passage was that despite the Magnus-derived downforce of the spinning driveshaft, the instability when exhaust gasses are added makes it a net negative.

[henra]

100% sure! the drive shaft is rotating forwards.. look at it this way..it is opposing flow over the top and accelerating flow at the bottom...air is slower at the top thus of higher pressure than the faster air at the bottom which of course has a lower pressure..and downforce is produced

Or to give a more practical example just think about a football or tennis ball. If you give it a forward spin, i.e. faster on the upper side it will descend faster whereas if you give it backward spin it will have a flatter trajectory.

[amouzouris]

100% sure! the drive shaft is rotating forwards.. look at it this way..it is opposing flow over the top and accelerating flow at the bottom...air is slower at the top thus of higher pressure than the faster air at the bottom which of course has a lower pressure..and downforce is produced

Or to give a more practical example just think about a football or tennis ball. If you give it a forward spin, i.e. faster on the upper side it will descend faster whereas if you give it backward spin it will have a flatter trajectory.

I was never much of a sports guy!

My understanding of the passage was that despite the Magnus-derived downforce of the spinning driveshaft, the instability when exhaust gasses are added makes it a net negative.

No it just makes the lift produced unstable which is something you don't want and it has e negative effect on the exhaust plume...it messes it up

maybe i need to rephrase it

[hairy_scotsman]

It could be done without mounting to the fairing. I don't have the resources to make a pretty drawing though. Sorry!

Something like this ?

Yup. Nice.

Thx!

[hairy_scotsman]

As a baseball and volleyball player, this brought back memories of when I first learned as a kid what makes a curveball or a volleyball cut shot curve, or a sinker sink.

Just think of it in terms of pressure differential. If a ball in flight is spinning forward (with the top rotating in the direction of flight), then air pressure on the top of the ball will be greater than if the ball were not spinning. Likewise, the pressure on the bottom of the ball (which is rotating away from the destination) will be lower than if the ball were not spinning.

Thus, the pressure on the top of the ball is greater than the pressure on the bottom of the ball, and the ball drops more quickly than it would if it were not spinning at all. All other things being equal, the faster the rotation, the quicker the ball will descend as it travels.