Technical analysis: Testing round up

After poor weather struck January's tests, last week's running at Jerez and Sakhir was vital for the teams to get through a full schedule. Ferrari, BMW Sauber and Toyota made the trip to Bahrain, while the others went to Spain - the only absentees being Force India (while they redesign their car around the Mercedes powertrain) and Honda.

But the weather once again played its part. It was hot and dry as expected in Bahrain materialised, but sandstorms over several days restricted running time. Still, the rain in Spain was predicted and the four teams were able to complete a reasonable amount of track time.

Technically, the cars were largely still in their launch guises, but given the extra manufacturing time since the Portimao test, a few new parts did arrive. Some of the developments were quite significant.

The new Red Bull Technologies car was a debutant in the hands of the Red Bull Racing team. Toro Rosso continued to test the 2008 car with slicks to allow the team to acclimatise to the tyres and test other systems on the car while they construct their own Ferrari-powered version of the RB5.

Diffusers

The noise surrounding Williams and Toyota's diffuser designs seemed to die down during the break between the tests. Assertions by the FIA that the teams had spoken to their technical delegates did not strictly declare the designs legal, but the wording of the rules appears to have been met by both teams.

It's possible that other teams have these sorts of designs in the pipeline for their cars, but have yet to debut them.

So any similar designs appearing before the start of the season are likely to have been in development before the last test. Any team without such a solution in the wind tunnel before the January Algarve test will probably struggle to get a design from scratch to a race before the Spanish GP in May. Equally likely is that other teams have tested these solutions in the wind tunnel, but have yet to get the flow conditions right ahead of the floor to feed the extra exit area, due to the lack of bargeboards etc.

Nose shapes

While it's still early days in development, the high or low nose debate still appears to be split. There's conjecture as to whether teams are opting for low or bulky noses for aerodynamic or packaging reasons. Clearly, there is the possibility that a low or sculpted under-nose shape could reduce the lift created by the FIA template middle section of the front wing.

But raising a more worrying possibility is the suggestion that these larger noses house batteries for the KERS system; sources suggest that some front wings also house an array of batteries. From a performance point of view, this packaging choice makes sense. The extra weight of KERS tends to sit towards the rear of the car, when the designers want more weight at the front. Placing any KERS element forward in the wheelbase would be beneficial to handling.

Contrasting the performance issue, is the safety issue of a detachable nose cone containing ten or so kilograms of charged lithium ion battery cells. Should the nose assembly impact another car, what is the chance of sending an electric shock into that car, the nose flying off towards marshals or spectators, or even the risk to mechanics during rapid nose changes during the race?

As long as the nose passes the FIA crash tests then the subsequent placement of batteries is currently free.

Developments

McLaren
They conducted an oil streak test at Jerez, while this is common for all teams it's rare to see McLaren carry one out at such a well-attended test.

Described as a 'flow vis' test by McLaren, it involves painting the car with a coloured liquid and then reviewing where the liquid gets dispersed by the airflow over the car. This is a simple and effective test to correlate simulation data and is not a sign of any aero problems for McLaren.

Heikki Kovalainen (McLaren MP4-24 Mercedes) testing in Jerez © XPB

The test reveals the surface flows and while this is not the most important element of the car's aero, it's still valuable and can be easily compared to CFD or wind tunnel tests. Of course, the test is not fully controlled; the fluid has a mass, a viscosity and the car isn't always in a straight-line, but the test is qualitative not quantitive, so the results are still comparable to other simulations.

No clever equipment is used to produce or evaluate the results, Paraffin and a fluorescent powder are mixed and sprayed to the car's surfaces. The colour of the powder is only important in as much as it needs to be easily seen, there is no need for it to have special properties. When the car returns to the pits, the team use conventional digital cameras to record the streaks.

These are reviewed back at the factory to prove whether the surface flows are as predicted. McLaren's test applied the fluid to the front wishbones. This was because, with the new neutral front wing section, the front suspension is the main flow conditioner over the centre of the car. With McLaren's steering arm placed mid-way between the upper and lower wishbones, the test was the first chance to see how this arrangement responds in the flesh.

A further development of the McLaren front wheel fairings was seen in the latter part of the Spanish test. The larger outboard fairings with the forward extensions were already seen in testing in January. These fairings have now been supplemented by similar inboard versions. Thus the tyre is closed in on both sides, between the forward perimeter of the tyre and a line above and below wheel.

This design makes use of the loophole in the regulations that provides an area for bodywork around the front wheels, but the rules do not demand they are specifically for brake cooling. Thus McLaren can fit these fairings legally.

The drawback with these fairings is that they must fit within the maximum width allowed for the car (1800mm), therefore McLaren must have compromised the car slightly by reducing the front track to be within the maximum width, including the outboard fairings. This loss of a few mm of width must be more than offset by the aero advantage.

Elsewhere, McLaren continued to run the 2008-spec rear wing. This is believed to be because the definitive high-downforce rear wing is not yet ready. The 2009 rear wing seen at the launch appears to be a lower drag wing, due to the complex slots and shaping on the endplates. Beneath the rear wing, McLaren also ran with an infill panel fitted to the centre of the diffuser. This reduced the volume in the middle of the floor, which would theoretically reduce downforce as the part appears to be an add-on. This may be an interim part, linked to the use of the wider 2008 rear wing.

BMW Sauber
With the limited running in Bahrain, the F1.09's only novelty appears to be the Ferrari-like combined pod wing and rear view mirror. Walter Riedl alluded to these parts at the launch so they were planned, and not a response to the Ferrari bodywork.

The sidepod regs do allow bodywork forward of the side impact structures, this area is exempt from the curvature and radius rules that limit aero development on the rest of the sidepods.

Fernando Alonso (Renault R29) in the pitlane at Jerez © XPB

Renault
At its launch, the Renault R29 gained an unfavourable response from fans and media alike to for its aesthetics. The boxy nose and bulbous undercut sidepods did not suggest they were linked to any subsequent developments. However, the parts tested in Jerez showed there is more thinking behind the R29 concept.

In Spain, the car gained a pair of full-length, curtain-like vanes running from the nose to the sidepod entries. As these parts sit beneath the nose, and do not sit lower than 100mm from the reference plane, they are perfectly legal.

Their function is more complex than the bargeboards seen on other 2009 cars and it appears as though Renault are extending the arched under-nose philosophy of the R28. The new curtain vanes take the flow from the middle of the front wing and channel it towards the undercut sidepods. From the undercut sidepod entries, the flow is contained by the coke bottle shape and routed over the diffuser's roof.

This may be Renault's method of sending higher-energy air over the diffuser for greater downforce. It seems an extreme and sensitive approach to the problems of the 2009 rules and it will be interesting to see whether the solution is retained, or replaced with a simpler turning vane solution.

Timo Glock testing the TF109 in Portimao © XPB

Toyota
The team continued to run with the complex diffuser and elegant front wing endplates seen at the Algarve test. These endplates replaced the equally attractive launch versions, with their bi-plane leading edge. Now, the endplate is simpler along its top edge but gains a vent in its side. The vent mimics the Renault solution seen back in 2006, as it takes the higher pressure air from the outside of the endplate and sends it along the inner face. This speeds up the flow exiting under the wing and helps send it around the front wheels. It is probably a lower drag solution than some of the more aggressive flick-ups we have seen on the outer face of the endplates this year.

Red Bull
Red Bull's first test was hindered not only by the Spanish weather, but also by reliability problems. But despite the limited track time, the car has started to expose more of its design secrets since its launch last week.

Firstly, not so apparent in the launch images is the extreme rake of the front of the monocoque. Newey said that the front of the chassis was raised something like 25mm, this goes to explain the different shape around the monocoque nose cone interface.

Sebastian Vettel (Red Bull RB5 Renault) in Jerez © XPB

Raising the nose section allows for a freer flow towards the sidepods, but at the cost of a higher centre of gravity. Chassis heights have stabilised for a few years, with Ferrari and McLaren noted for their jacked up front monocoque sections. With such a raked section, Newey has had to shape the underside of the nose, which becomes an aerodynamic leading edge in this position. Equally, he has had to shape the upper surface to send the flow over the top of the car most effectively, leading to the twin humps on the edges of the nose.

With no photography of the diffuser allowed at its roll out, the car's clever interpretation of the 2009 rules was hidden. Newey has eschewed a wider diffuser (max allowable 1000mm) and instead opted to keep it as wide as the rear wing (800mm). While this limits the diffuser's exit area, it does allow for the rear wing endplate to extend down to form a wall to seal the exit flow. The rear wing endplates can extend further behind the car than the area allowed for the diffuser. Presumably, Red Bull have found more benefit from this sealing than the extra would have given.