F1 2D Rear Wing Profile

SlotGapSeparator

Like any aero surface, rear wing profiles used on F1 cars are a closely guarded secret. Teams will constantly develop their own profiles and not base the designs on the commonly available NASA profiles or similar. While complete and recent F1 rear wings will appear on the market, they are expensive and leaves the technical fan unable to gain any data from them. However, the simple rear wing slot gap separator, mandated to deter the teams from flexing their rear wing profiles for an aero-elastic stalling effect, are ideal for gaining basic 2D geometries. I have just such a component from a Red Bull RB6.

2015-01-29 09.53.11

This makes the profile useful as it’s from a post 2009 rear wing and of course from a highly capable aero team. It’s important it’s a post-2009 profile, as the wings were wider, shallower and lower mounted before that (I have a Honda 2D Rear wing profile from the earlier era too). Thus the 2D profile will be pre-DRS and close to the current regulations regarding the 3D volume it needs to sit within.

2D_rearwingprofile_steepest
The resulting wing would sit in a box (Y) 750mm wide, (X) 350 long and (Z) 220mm high, being 950mm above the cars reference plane at its highest point. Placing the Red Bull profile into that space, finds the wing will not entirely fill the available space in side profile, either the wing will be steeper and not fill the X axis, or be flatter and not fill the Z axis. This gives an angle of attack of between 23-28 degrees, a 5 degree sweep.  It could be that this isn’t a maximum downforce force profile, as it isn’t utilising its maximum potential size.

In terms of its shape, there a few observations I’ve made from what I’d expected to see in a wing profile.  While the main plane is quite conventional, with a rounded leading edge and taper to a near point at its trailing edge. It’s the flap that has the unusual gemometry.

Firstly the flap’s leading edge is not simply rounded, rather the stagntion point is higher up the leading edge, making for a larger radius leading down into the slot gap.  Clearly this will increase the funneling effect of the flow over the main plane into the slot gap.  The first third of the flap’s upper surface of the flap is particlulalry rounded and convex, not concave as I would have expected.  Then this rounded upper surface swithes back into a reflex curve about another third along its length, to create a concave rear third.  At this transition the flap’s profile slims to a near flat shape, barely 2mm in section thickness.

2D_rearwingprofile_sweep
Basic wing profile dimensions (a scaled PDF scan is linked at the bottom of this post) are as follows:

Main plane:
Chord – 250mm
Max section – 35mm

Flap
Chord – 175mm
Max Section – 24mm

2 Profile Assembly
Chord – 375mm
Slot gap 8mm

I’d welcome any CFD analysis of this wing, both as a static wing, with a sweep in angle-of-attack, but also with the effect moving the wing’s flap for a DRS effect.

However, there are some factors that we will have to take into account with the results. An F1 wing works with a carefully managed onset airflow, such that the wing’s leading edge meets a downwash and not a horizontal airflow. Plus the wing work in cascade with the diffuser and Beam wing upwash. These factors along with the use of a Monkey across the Y75 axis, will significantly reduce the separation likely to occur under the wing. Plus the endplate design is also optimised with the louvers to reduce induced drag at the wing tips. Endplate dimensions allow the end plate to start 50mm ahead of the wings leading edge and trail it by a further 600mm. Plus endplate thickness needs to be included in the total 750mm span.

 

Link to A3 PDF Scan 2D_rearwingprofile_A3

 

2009 Rear Wing regulations

3.10.2

Any bodywork behind a point lying 50mm forward of the rear wheel centre line which is more than 730mm above the reference plane, and between 75mm and 355mm from the car centre line, must lie in an area when viewed from the side of the car that is situated between the rear wheel centre line and a point 350mm behind it. When viewed from the side of the car, no longitudinal cross section may have more than two closed sections in this area.

Furthermore, the distance between adjacent sections at any longitudinal plane must not exceed 15mm at their closest position.

3.10.3

In order to ensure that the relationship between these two sections cannot change whilst the car is in motion they must be bridged by means of rigid impervious supports (including any adjustment mechanism) arranged such that no part of the trailing edge of the forward section may be more than 200mm laterally from a support. These rigid supports must:

– fully enclose the two complete sections such that their inner profile matches that of the two sections. Their outer profile must be offset from the inner profile by between 8mm and 30mm and may not incorporate any radius smaller than 10mm (‘gurney’ type trim tabs may however be fitted between the supports)

– not be recessed into the wing profiles

– be arranged so that any curvature occurs only in a horizontal plane

– be between 2mm and 3mm thick

– be rigidly fixed to the two sections. Some form of adjustment mechanism between the sections may be incorporated for the sole purpose of allowing adjustment of the sections relative to one another whilst the car is in the pits

– be constructed from a material with modulus greater than 50GPa.