HILO OFICIAL Pretemporada F1 2015

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http://www.autosport.com/news/report.php/id/117726



Barcelona F1 test: technical developments to look out for

By Craig Scarborough
Wednesday, February 18th 2015, 18:52 GMT




As we head into the second test of Formula 1's pre-season we shouldn't expect to see dramatic differences in car design or team performance but changes will be visible.
New parts, as well as those unnoticed at the first test, will be on display so it's important to spot the trends and see who's pushing their car development the hardest.
Here are the key areas to look out for at Barcelona this week:

Nose
Several teams are running an interim nose. As early testing is never about the absolute performance of the car, the priority was a design that could easily pass a crash test.
Initially costing around 60 points of downforce, the 2015 nose may not be a primary performance differentiator between the teams, but it does influence the rest of the car.
Designs so far fall into two camps, long or short, with Ferrari and McLaren adopting the long nose design.
Most other teams have kept the nose short, with only Williams and Red Bull actively using a thumb-tip arrangement.
There's no right or wrong solution. Keeping the nose short allows more air to pass under the nose towards the rear.
Equally, a long nose can use the forward tip to influence the airflow over the front wing to create complex flow structures to pull air under the nose for the same effect.
Increasingly teams are using the front wing mounting pillars as turning vanes to create vortices to pull air under the nose, with the T-shape cross section created by the thumb-tip element used to guide these vortices.
If there is a common direction, it will be towards shorter noses with arched under shapes and complex front wing mounting pylons.
Mercedes is likely to introduce a short nose, as its current design is a bulky wedge shape and the rest of the car was largely in 2014 aero specification at Jerez.

Blown axles
The narrower front wings of 2014 forced teams to work harder to deflect airflow around the front tyre to keep its turbulent wake away from the central bodywork of the car.
During 2014, front wing endplate designs became less twisted. So it was a surprise that three teams have already adopted blown axles with their 2015 cars: Ferrari, Red Bull and McLaren each introduced their version of this aero trick.
Most teams already divert airflow through the brake ducts and out through the wheel without any brake cooling effect.
This flow creates a greater outwash effect around the front tyre, working with the front wing endplate to keep the car's rear-end aero clear of the tyre wake.
The blown axle is an extension of the same concept. But this does create drag.
The blunt open face of the axle makes pitstops more complex, as the wheel gun socket isn't guided onto the wheel nut by a pointed axle tip.

Diffusers
Perhaps the most important aero system on the car is the floor and its diffuser, because this provides more than a third of its downforce with very little drag.
Every team will expand the diffuser's exit to the maximum allowed, then wrap this exit with two or three vane flaps to try to reduce the pressure behind the diffuser for even greater airflow under the floor.
But eventually the regulated geometry halts further development in this area. So the focus moves to the vanes inside the diffuser and the way the 'boat tail' encroaches into the diffuser's volume.
These vanes are more numerous than in recent years. Just as with slots in a wing design, the gaps between the vanes allow the air to be turned more aggressively without flow separation.
As the car's underside is stepped, the 50mm difference between the centre of the floor and the raised sections under the sidepods creates the need to merge both surfaces into the diffuser.
This creates what's known as the boat tail, where the deeper centre floor section forms a "V" inside the diffuser.
Up until 2014, teams used the starter-motor slot as a means to keep the airflow going, but this was closed off by rules meaning a hinged flap had to cover the opening.
So the trend has been to add a series of tiny fins under the floor to improve the airflow. These fins act a vortex generators, and the spiralling airflow coming off them keeps the air attached to the steep boat tail section.
Another means to manage airflow in this area is the dipped centre section. Last year, Mercedes started with an obvious "U" shape in the middle of its diffuser to improve the airflow acting the starter motor hole.
Late in the season Mercedes dropped this, but McLaren adopted it. So far this year both Williams and Sauber have tested this design.
Teams with both multiple vanes and the boat-tail fins are the ones working the diffuser hardest.
The high rear ride heights teams will run at Barcelona should allow us a clear view of some of these developments.