Silverstone YDT: Test Summary

The Young Driver Test (YDT) at Silverstone had more of a purpose than a normal YDT (the last being held in Abu Dhabi in November 2012) thanks to the calamities with the Pirelli P-Zero rubber so far this year. “Young” drivers were still in abundance, but the FIA introduced a few changes to ensure the safety of the future tyres that will be introduced for Hungary next weekend.

The FIA gave permission for each team to have one full day of running with either one of their driver’s or half a day for both of the drivers. Most teams took the opportunity to capitalise on having an experienced driver in the car, although they were restricted to a program set by Pirelli to clarify how the new tyre will behave from next weekend onwards.

The FIA also stated that teams could not make any major setup changes (such as ride heights, rollbars, spring rates) to the cars when using a current driver to make sure that they did not gain an advantage with their current driver lineup. However small alterations such as tyre pressures and wing angles could be changed if they wanted to.

Some teams chose not to field a “young” driver and instead deployed the expertise of a test driver who knows the team inside out. This is still permitted within the regulations as they do not participate in any Grand Prix weekend in the F1 calendar.

Despite the slightly different rules, the normal stream of updates continued to make their way to the cars for the three-day test.

Sensors

It’s all well and good having updates to bring to the car, but without measuring data from these components you cannot improve the car. This is why teams build unique sensors that are designed to measure specific parameters of the car whilst it is running.

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These sensors generally come in the form of pitot tubes: commonly found on aircraft (next time you’re by the wing of an aeroplane, look out the window and you’ll probably see one), the tube is designed to measure airflow velocity. Teams will build varying sizes of array to accommodate a certain amount of these tubes depending on the area of the car.

Above we can see an image of the Ferrari with a small arrangement of pitot tubes attached to an array. These will all be linked to what is effectively a blackbox attached to the car, receiving data from each tube about the velocity of airflow that is hitting them.

The placement of the sensor will tell us what the team wants to measure. In the above case, Ferrari have placed the array in the region in which the exhaust gases will hit the floor of the car via the coanda (the behaviour of a fluid passing out of a jet and onto a surface. Hold a spoon under an open tap and see what happens to the water as it leaves the trailing edge…) and downwash effect. This will allow the team to see how changes to the bodywork or exhaust mapping can change the velocity of the flow hitting this region. Ideally they will want higher velocity flow to try to replicate the Exhaust Blown Diffuser (EBD) effect that was banned after 2011.

Many teams placed a large grid of tubes at the section just beyond the airbox and over the sidepods to measure the flow coming off of various components. The front wing will have a large impact on the flow rate at this section of the car as it is chucking large volumes of turbulent air upwards and backwards towards the rear of the car. The tubes will be able to measure the speed of this flow and the engineers may be able to decipher how this will affect components downstream, the rear wing for example.

Over the course of the testing period, the data engineers will be able to map the flow structures of the car by placing these tube arrays at various stages of the car. They will then be able to compare this data with that taken in the wind-tunnel and Computational Fluid Dynamics (CFD) systems back at the factory and see if they correlate. If there is positive correlation then the designers can be confident that whatever they bring to the car should work as desired. If the results don’t match up, things can get very tricky and engineers and designers can be led down a rocky road. Ferrari have had poor correlation over the last few years and look where they are…

There are other sensors, too. Teams commonly use infrared sensors to measure tyre temperatures but there are also other interesting devices.

Lotus use device called the Kistler RoaDyn.

The Enstone outfit have been utilising this system for a few years now and it appears to be a good tool for them. The RoaDyn measures four parameters of the wheel in all three axis: pressure; force; acceleration; torque. The measurements the devices gather will determine how the tyre behaves as the car travels around the circuit. This sensor would have been very useful for the YDT at Silverstone because of the new type of tyre that they are testing.

McLaren

The sensors above will have been used for a wide variety of objectives, and constant straight-line speed runs will gather the appropriate information needed to alter any designs on the car. McLaren were no exception to this, but also implemented the now widely used Flow-Visualization (Flo-Viz) on a slightly updated front wing and turning vanes.

The team tested their current front wing with new mounting pillars. They are longer than their predecessors, stretching back as far as legally possible (in line with the trailing edge of the wing endplate) to guide flow more directly to the T-Tray.

McLaren sprayed the wing with Flo-Viz for analysis. The appearance of the Flo-Viz paint appeared to be quite uniform and the flow does not appear to detach which is a good sign. However it would be very rare for airflow to detach here as it is passing over an element that is placed vertically rather than horizontally. The Flo-Viz will be particularly useful to show how the flow behaves across the pillar and where it leads to afterwards.

The team also returned to using the three-element turning vanes beneath the chassis. They were abandoned after the Jerez pre-season test because they did not allow easy access to the key components of the pullrod suspension layout beneath the chassis, leading to longer setup change time which compromised running time.

Perhaps McLaren now feel that this season is dead and buried and it is worth concentrating further on aerodynamic development for next season, or they have found a go-to setup that does not require a lot of messing around with during the race weekend to get the car in tune with the driver.

Another theory is that the new tyre construction coming for Hungary does not interfere with the flow structures of the turning vanes. McLaren believe that the current 2013 tyre construction has a huge influence on the aerodynamics of their car due to the softer sidewalls interacting with the bodywork in ways that were not anticipated. With the harder sidewall tyre coming in next week, we could see them move up the grid.

The Woking based outfit added an additional vortex generator fence to the top of each sidepod, making a total of six (three each side). This should boost the downwash effect over the exhaust plume, aiding the EBD effect and sealing the gap between the rear tyre and the floor/diffuser wall. Each fence reacts with eachother to produce a net vortex, therefore simply adding fences on top of the sidepod will not necessarily give the car more downforce.

McLaren concentrated heavily on the crucial region where the exhaust plume makes contact with the floor near the rear tyre. They coated this section of the floor with a blue material. I may be incorrect, but my guess is that the blue coating has a melting point similar to that of the temperature of the exhaust gases that are reaching this area of the car. Rather than relying on an infrared camera, the engineers will be able to visibly examine how the gases interact with the floor and how the temperature is spread along its surface. The designers can then make changes to the vortex generators, sidepods and engine mapping to meet a desired criteria.

On Thursday, the team examined the same area of the car but with a different sensor. These horizontal sensors may be able to read pressure and temperature, effectively mapping how the exhaust gases change within these parameters along this stretch of the floor. This is the same idea as the blue coating but data can now be collected on the area as well as examined visible evidence.

Sauber

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Sauber introduced an all-new full coanda exhaust system at the YDT. It featured an under-tunnel but retained its exhaust bulge from the previous system where the ramp now extends downwards from.

sauber exhaust

I have tried to explain how it works in the diagram above. The yellow line, dotted as it passes through the tunnel, is airflow coming from around the sidepod. The red area represents the exhaust plume (although I would expect it to be firing out at a steeper angle) and the green line shows the airflow coming over the top of the sidepod pushing down onto the plume – downwash.

Sauber previously had a semi-coanda exhaust system, whereby the exhaust gases had to “jump” from the sidepod down to the floor whilst flow still passed beneath it. There was no tunnel on the previous system. The system they are now using was pioneered by Red Bull last season, although it tends to work better for Renault-engined cars.

Sauber also appeared to be trialling their Drag Reduction Device (DRD) for the first time since pre-season testing. The device utilises ears each side of the airbox, like the Lotus system, to trigger a fluid switch within the engine cover of the car at high speed, sending air up the vertical column, in to the low pressure region beneath the rear wing and stall it.

Where the Sauber system is different is where the airflow exits when the device is not active. On other cars we see ductwork exiting the engine cover and beneath the Y75 Monkey Seat winglet. Sauber however have been able to tap unwanted flow off within the engine cover, exiting at the same place where air cooling the engine and transmission would be released.

Lotus

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Lotus continued their work with their race-proven DRD at Silverstone this week, with the device’s debut race at the very same venue last month.

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The system was no different (as far as I could tell) from that used recently, but the image above shows some key features of their device. The yellow circle highlights a number of holes within the stalling column of the system. At speeds just below the activation point of the device, some airflow still leaks up the stalling column instead of exiting beneath the Monkey Seat duct, which can disturb the rear wing’s downforce. These holes bleed off this unwanted flow before they can reach the bottom of the wing. When the device is active, the pressure within the stalling column can overcome these small holes and will therefore not greatly effect the stalling of the wing.

The orange arrow shows how the pillar is attached to the base of the rear wing. This could be acting as a stabiliser at high speed, reducing the movement of the pillar and therefore increasing the stalling effect.

Toro Rosso

Toro Rosso also evaluated their DRD for the first time this week. Despite claims that they tried such a system in Abu Dhabi last year, I have been informed that this is incorrect. The system is quite clever as all of the components that produce the switch effect within the device are all hidden inside of the engine cover, much like Red Bull’s when they debuted it (in Abu Dhabi, incidently).

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9 thoughts on “Silverstone YDT: Test Summary

    1. thewptformula Post author

      Didn’t get anything! The new sidewalls will probably make the biggest difference rather than the compounds in my opinion. They are a lot firmer and do not flex as much under loading. This totally changes the flow structures around the tyres and can definitely change the way some of the components work.

      Mercedes may be getting tyre data, such as the operating window for ‘x’ compound or the lap time delta between ‘y’ and ‘z’ compounds, from Pirelli but they are hugely disadvantaged by missing this test for the above reason.

      Reply
  1. seventhgearblog

    Great article, well written as always!
    I’ve been stuck with no info, as I had no way to follow the YDT. But this is the best way to meet all that happened.
    It looks like teams have been focusing specially on exhausts and tyres, which will sadly be the dominant fact of the upcoming races.
    It is also interesting how teams begin to develop the DRD, which will be determinant next year, when it is finally evolved.

    Reply
    1. thewptformula Post author

      Cheers!

      True, but they are both big variables, especially when it comes to exhaust plume interaction with the rear tyres, as well as tyre dynamics.

      I get the feeling that it may well be banned, despite it being totally legal. Hope it isn’t though, teams have spent a lot of money to just roll it out to test…

      Reply
  2. Pingback: 2013 Hungarian GP Tech Highlights | theWPTformula

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