Abu Dhabi Test: Red Bull Aero Rake

Red Bull started the Abu Dhabi Young Drivers test with a mass of aero testing equipment fitted to the RB7. Although the test is supposed to be to assess young drivers, this is the first open test since the season started and teams make use of this time to gather data from the car. In Red Bulls case this was a repeat of tests from last year, where the front wing ride height and wake is being measured by a range of sensors.

Pictures via F1Talks.pl & SuttonImages.com
Airflow around the front tyre is critical with the post-2009 wide front wings. The ever more complex front wing endplates direct the airflow around the tyre. This effect varies greatly with front wing ride height, so that when the wing flexes down under load at speed, the airflow changes. I have learnt from F1 aerodynamicists that the effect of the endplate on flow around the wheel as the wing flexes down, is perhaps more important than downforce gained the wing being closer to the ground. So the Red Bull and also Ferrari tests are critical to understand how the airflow passes around the tyres with varying wing ride height.
Clearly the gains from flexible front wings will be an ever greater performance factor next year. Even though the FIA rules amended for 2011 were even more stringent than in 2010.

In Red Bulls the case the set up consists of three main elements; the aero rake, ride height sensors and the cables holding the front wing.

Wing mounting cables

Wing cables & Nose hump – Picture via F1Talks.pl & SuttonImages.com

Ride Height Sensors

Ride Height Sensor – Picture via F1Talks.pl & SuttonImages.com

Ride height Sensors – Picture via F1Talks.pl & SuttonImages.com

Aero Rake

Rake detail – Picture via F1Talks.pl & SuttonImages.com

My interpretation of how the rig works is: the wing is allowed to deflect at speed to a specific height, this is controlled by the cables from the hump on the nose. By limiting droop, a number of wing ride height settings can be assessed during the runs. Laser ride height sensors both in the centre and at the front and rear of the endplate will confirm the actual ride height and wing angle being tested. Then the rake will take measurements of the airflow. The driver will then run at a fixed speed along the straight, keeping a consistent speed will ensure the data is consistent and the amount of wing flex can be predicted for each run.
This will create an aero map of flow across the wing and with the wing at different attitudes. The data from the tests will be used to confirm CFD\Wind tunnel results and direct the team in deciding how the wing should flex in 2012.

We can now look in detail how the rig is made and how it works.

Cables holding the front wing

During some runs we saw the cables lying loose between the wing and the hump. Which confirms they are cables and not solid rods, as with the rake mountings. Being cables they could not be for measuring wing position, as not being stiff, they would not be accurate enough. With the size of the nose hump and the other equipment to measure ride height, I now believe they are to control the droop of the front wing. Perhaps the test wing is more flexible than the usual race wing in order to achieve more attitudes under load. Its possible the hump contains hydraulics to adjust the droop of the wing to different attitudes during each run. The 2009 Red Bull used hydraulics in the nose to control the then legal adjustable front wing flap, so it’s a proven approach to fit more hydraulics into the nose cone. Being able to alter wing attitude on the move would greatly improve the amount of data gathered from each run. With there being two cables for each wing, one mounted on the main plane and the second on the flap, the wing could be controlled not only in droop but also the angle of attack. So that the wing could reproduce different beam and torsional stiffness of a future wing.

Ride Height sensors

We have seen laser ride height sensors fitted to cars through Friday practices and extra units fitted for testing. For the front wing rig Red Bull ran five ride height sensors on the wing. The central unit is fitted to the neutral centre section of wing. This would measure true wing ride height, as the centre section is relatively stiff and is not part of the deflecting structure of the wing. Then two ride height sensors are fitted to front to the front and rear of the endplate. These would measure the ride height of the wing tips. Using the centre ride height sensor as a base line provides the amount the wing tip is deflecting. Just as with the double cable arrangement supporting the wing, the two endplate ride height sensors would measure any change in angle of attack, the delta between the front and rear sensors showing the wings angle of attack.

Aero Rake

With the wings attitude controlled and measured by the cables and sensors, the wake of the wing is then measured by the aero rake. This is an array of sensors measuring air speed, velocity and perhaps even direction. Two rows of rakes are employed and these are securely mounted to blisters on the nose cone. Just as with the wing mounting cables these struts may be attached to hydraulics to raise the rake over a range of positions, to map a wider area behind the wing. A slightly messy part of the mounting system if the bundle of cables exiting the rake and passing up into the nose cone to be attached to the cars telemetry system.

9 thoughts on “Abu Dhabi Test: Red Bull Aero Rake

  1. Brilliant analysis, some fascinating insights. Particularly interested in the factoid about the relative importance of front wing downforce generation vs. airflow around the front tyres from a flexing wing.

    Also, what about the importance of giving these so-called ‘young drivers’ a chance to, y’know, drive? Getting them to perform straight-line fixed-speed runs down the straights is a little…rubbish, no? *sigh*

  2. Movable aerodynamic bodywork is banned in letter and spirit, but you can run rigs like this at a young drivers’ test and Charlie isn’t interested?

    I’m growing apart from F1 because it’s just becoming too artificial, from engine rev limits to silly tyre compounds and a DRS system that’s a farce compared to what the TWG originally specified. Insulting fans’ intelligence by having one public rule book and one set of hidden ‘understandings’ etc adds to this.

    • In testing anything is allowed. Remember the extremely flexible front wing of Red Bull in the testing prior to 2011? No one objected.

      For the artificial part … Well, you can never escape that – the rest means spec series. F1 has always been about clever engineering and technical solutions. Though I’d agree that the ‘hidden’ parts make me upset sometimes, i.e. this team have found yet another loophole in the rules, so it’s going to reign the season …

      To me, the saddest part is the great distance between the teams and frankly, I don’t see it changing next year, too.

      What we need to make sure is that F1 remains “sport” and not “entertainment”

  3. Very good analysis! It would be a joy to be involved in this experimental work. This rig also confirms that RB car wings are designed to be flexed. hehehe. I love it when clever engineers find creative ways to work within the regulations (i.e. the front wing test procedure or how the rules are enforced).

  4. The cables are measuring the pulling force of the wing as it flexes downward. Optical sensors are for measuring height of wing at certain points. Aero rake is for measure airflow speed over different areas of wing. With all the telemetry they have of the car going around the track, they have all the information they need to computationally model the wing flexing and/or vibrating under all conditions the the car and track represent.

    I’d put my money on them trying to pinpoint the cause of the fluttering of the new wings. They are gremlin hunting.

    • At least for aircraft to understand flutter, you need to have air flow information and local accelerations of the part to be analyzed (wing, fueslage, …) and defined inputs (doublets, sine sweeps, … ) to your systen/vehicle. Thus the teams would need more sensors and measurements of the track.

  5. When you describe the aero rake you say: “this is an array of sensors measuring air speed, velocity and perhaps even direction”. I think there is bit of redundancy here, as velocity is just speed in a given direction.

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