Acta Polytechnica


doi:10.14311/AP.2018.58.0308
Acta Polytechnica 58(5):308–314, 2018 © Czech Technical University in Prague, 2018

available online at http://ojs.cvut.cz/ojs/index.php/ap

ANALYSIS OF DALLARA T12 RACE CAR FRONT WING
VIBRATIONS

Pavel Alekseevich Sorokina, Kirill Stanislavovich Khryakovb,∗,
Michiel Gommersb

a Russian University of Transport (RUT – MIIT), Institute of Transport Engineering and Control Systems,
Obrazcova 9b9, 127994 Moscow, Russia

b Charouz Racing System SE, Tovární 500, 267 53 Žebrák, Czech Republic
∗ corresponding author: kirillkhryakov@gmail.com

Abstract. This work investigates aerodynamic elements’ vibrations of high-speed vehicles on the
example of the Dallara T12 race car front wing. Made up energy spectrums of wing vibrations for three
specific cases arising during driving on the circuit.

Keywords: race car; Dallara T12; front wing; sensors; spectral analysis; energy spectrum; vibration
frequency.

1. Introduction
Motorsport is the main testing ground for all innova-
tions and technical solutions used in the road trans-
port. Racing, where the difference between winning
and losing is a matter of few tenths of a second, en-
courages the leading manufacturers of racing cars to
invest huge amount of resources in the development
and improvement of their cars.
In the wide spectrum of all kinds of racing series,

the top of the motorsport is rightfully taken by circuit
racing. The main reason for the beneficial effect of
circuit racing on the development of the road transport
is that the main task of the car in this kind of racing
is not to reach the maximum record speed, but to pass
a complex circuit with different turns in the shortest
time.

From this, it follows that the best car for this kind
of racing is a car capable of driving equally fast on
straight lines of the road and in the corners. This
means that the car should have a good acceleration,
effective braking, and be able to keep the cornering
speed as high as possible.
However, fast driving in corners is limited by the

frictional force between the wheels and the asphalt.
One of the most effective ways to increase this force
is the use of aerodynamic elements generating the
downforce, which allows to press the car more tightly
to the road [1, 2].
A lot of new aerodynamic elements, which were

tested in wind tunnels or developed with CFD mod-
elling (Computational Fluid Dynamics), were designed
based on stationary conditions. In actual conditions,
when the car is moving on the road, vibrations, which
reduce the efficiency of these elements, occur.

It becomes obvious that it is a great practical inter-
est to study the influence of vibrations on the down-
force level. To start this research, it is necessary to

first investigate the vibrations of aerodynamic ele-
ments. In this article, the vibrations of the Dallara
T12 racing car’s front wing are studied [3, 4].

2. Preparation for experimental
research

The assembly of the Dallara T12 racing car’s front
wing (Figure 1) consists of carbon parts fastened to-
gether by steel bolts [5].

The mainplane of the wing is fixed at the ends with
the endplates, which serve to stabilize the airflow along
the edges of the wing and eliminate the end vortices.
In the rear part of the endplate, there is a nolder,
which improves the interaction of the airflows that
escape from the wing with the vortex flows formed
around the rotating wheel of the car located just
behind the front wing [6].

In the middle of each console part of the mainplane
of the wing, there are flap mountings. Between these
mountings and endplates are installed flaps of the
wing, fixed with bolts.

In the endplates and flap mountings, there are 32
holes for changing the angle of attack of the flap. Thus,
by moving the adjusting bolt between these holes,
it is possible to adjust the level of the downforce
of the front wing by changing the angle of attack
of the flap [7]. In this case, the minimum angle of
attack is 0°, provides the lowest level of downforce
and the least aerodynamic drag. The maximum angle
of attack of 32°, corresponds to the maximum level of
the downforce, but also leads to the maximum value
of air drag. Thus, by adjusting the angle of attack of
the wing with a step of 1°, you can achieve the best
balance in the ratio of downforce – drag, depending
on the race track.
The assembled wing, using special mainplane

mountings made of an alloy based on aluminium, is

308

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vol. 58 no. 5/2018 Analysis of Dallara T12 Race Car Front Wing Vibrations

Figure 1. The assembly of the Dallara T12 racing car’s front wing.

Figure 2. Aluminium bracket with mounted sensors for measuring the vibration of the wing.

attached to the nose cone of the car. To improve the
aerodynamic flow, these mountings are closed with
special carbon fairings. The nose cone assembly with
a wing is fixed to the chassis of the car with four quick-
release bolts, providing a reliable and rigid fastening
with the possibility of a quick dismantling.

The assembly of the Dallara T12 racing car’s front
wing, due to its design features, is most prone to
vibrations of two types: vertical oscillations of the
mainplane of the wing and twisting vibrations of the
assembly endplate – flap – flap mounting – mainplane
of the wing [8].

To measure the characteristics of these vibrations, it
was suggested to install two sensors: one for measuring
the vertical displacements, the second for measuring
the twisting.
To measure the vertical movements of the wing,

a laser sensor K-RHL2, made by the company “CA
Sensors” (Great Britain), was used for measuring the
ride height (clearance) .
The K-RHL2 sensor operates on a non-contacting

principle, measuring the distance to the road with a
laser beam. Reflected from the surface of the road, the

laser beam is perceived by the CCD-matrix, by means
of which the distance to the surface is measured.
The signal from the sensor is transmitted via a 3-

core cable (power, signal, ground), which is connected
to the sensor using the special purpose connector
ASL006-05PC-HE, manufactured by Deutsch (USA).

To obtain the characteristics of the twisting move-
ments of the wing, the GYRP-1 axis gyro sensor man-
ufactured by “Texense” (France) was used.
The sensor is made in the form of a MEMS de-

vice (microelectromechanical system) and measures
the speed of rotation of the sensor body around one
axis. Inside the gyro sensors, made on the basis of
MEMS device, there is a vibrating silicon ring, which
allows to provide a high accuracy of measurement in
conditions of strong vibrations. When this ring of
angular velocity is acted upon, a Coriolis force arises
that deforms the ring and thereby causes its radial
displacements.

Along the perimeter of the ring, there are uniformly
installed drive-converters. Some of them excite and
control the primary working amplitude of the vibra-
tion of the gyro sensor and the other transducers deter-

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P. A. Sorokin, K. S Khryakov, M. Gommers Acta Polytechnica

Figure 3. Motorland Aragon race track layout.

mine the radial displacements caused by the Coriolis
force and the proportional angular velocity of the rota-
tion. All converters work in pairs. Sensors-gyroscopes
working on this principle are placed in a sealed enclo-
sure that allows to keep a vacuum environment inside
and thus prevent the influence of changing physical
air parameters on the accuracy of the output signal.

The signal from the sensor is transmitted through a
3-wire cable (power, signal, ground) 3X26AWG FEP,
which is connected to the central circuit of the car
using the special purpose connector ASL606-05PN-
HE, manufactured by Deutsch (USA).
Both sensors were securely attached to the alu-

minium bracket shown in Figure 2. The bracket was
installed between the mainplane of the wing, the flap
and the endplate on the right hand side of the car.
This technical solution allowed the sensors to be rigidly
fixed on the elements of the wing, while not violating
their integrity by drilling additional mounting holes.
Signals from the sensors were transmitted to the

vehicle’s on-board computer, located in the cockpit of
the driver. Sensor cables were laid along the trailing
edge of the mainplane of the wing, which ensured the
least loss of downforce.

However, due to the fact that the installation of the
bracket with sensors and the laying of cables somewhat
violated the aerodynamic efficiency of the right part
of the wing and partly reduced the downforce, it was
decided to increase the angle of attack of the right
flap by one position (+1°). This decision was based
on the fact that the sensor cables were attached to the
wing trailing edge by using the tesa tape. The rough
surface of the tape slightly disturbed the boundary
layer, which could lead to an earlier separation of the
flow from the lower surface of the flap. To compensate
for a slight drop in the downforce caused by an earlier
flow separation, it was decided to increase the flap
attack angle by the minimum possible value (1° only).
According to Dallara T12 Aerodynamic manual [9],
an increase of the flap attack angle by 2° will lead to

a significant increase of downforce, which can have an
effect on the car balance and disturb the driver. Thus,
the angle of attack of the left flap was 23°, and the
right angle of attack was 24°.
This configuration of the front wing’s settings al-

lowed to level the aerodynamic balance of the car and
to simplify its management.
With the help of a special software to control the

on-board computer of the car, the vibration measure-
ment sensors have been calibrated in an accordance
with the recommendations of the manufacturers. The
frequency of reading of the signal was set to 100Hz
for saving the memory of data logger and for a conve-
nience of comparison with other parameters of the ve-
hicle dynamics, measured by sensors with a maximum
frequency of 100Hz. For this type of research, this
frequency of signal measurement is sufficient, which
will be further confirmed by results of the research.

Also, during the tests we, used standard sensors
installed on the car and measured the following pa-
rameters: car speed, rpm, longitudinal and lateral
acceleration of the car (the sensor is installed near the
centre of gravity of the car), steering angle, throttle
position, pressure in the brake system, gear change,
activation and deactivation of the active rear wing
flap (drag reduction system), the movement of the
shock absorbers, roll on the front and rear axles of
the car.
The analysis of the above parameters allows us to

determine the movements and vibrations of the chassis
of the car, which must be taken into account when
determining the relative vibrations of the front wing.

3. Experimental research
Experimental research to determine the characteristics
of the vibration of the Dallara T12 racing car’s front
wing were conducted on the Motorland Aragon race
track (Spain). A layout of this track is presented in
Figure 3.

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Figure 4. Dallara T12 racing car’s front wing vibration graph.

Figure 5. Front wing vibration graph in the first characteristic case.

The configuration of the track, 5345m long, con-
tains 18 turns with different radii. The maximum
elevation difference is 50m.
The driver passed 8 laps, which totals to

42.239 km, and showed a fastest lap time of
1:40.730 (the time is represented in the format min-
utes:seconds.thousandths of a second).
During the test runs, the southeast wind blew at

a speed of 5m/s. The air temperature was 13.3 °C,
the temperature of the asphalt was 16 °C, and the air
humidity was about 55%.
The data obtained as a result of testing, for the

convenience of perception, are expediently presented
in the form of a graph in which the time is measured
along the abscissa axis and the physical quantities

(speed, displacements, etc.) are measured along the
ordinate axis.

In Figure 4, there is a graph showing the car speed
in conjunction with the vertical and twisting deforma-
tions of the wing during the fastest lap.
This form of representation of experimental data

makes it quite easy to determine where the car was lo-
cated at a certain point in time. The smooth growth of
the car’s speed (red line) corresponds to the movement
along the straight section of the track with acceler-
ation and the sudden drop in speed corresponds to
braking before the sharp turns.
Figure 4 clearly shows that the oscillations are a

non-stationary process, depending on a variety of
different factors. These include: speed, acceleration,

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P. A. Sorokin, K. S Khryakov, M. Gommers Acta Polytechnica

Figure 6. Front wing vibration graph in the second characteristic case.

Figure 7. Front wing vibration graph in the third characteristic case.

curvature of the turn, the quality of the road, driving
style of the driver, car set-up, etc.

However, a practical interest is the behaviour of the
wing in specific situations, for example, at the entrance
to the turn, when exiting from it, while driving along
a straight section of the road, etc. Therefore, it is
advisable to identify the “characteristic” areas on the
graph and subsequently explore them separately, as
processes independent of each other.
The first characteristic case corresponds to a colli-

sion on a high curb at the entrance to Turn 9. The
car drives at a constant speed of 85 km/h with left
wheels on a curb height of 4 cm (Figure 5).

The second characteristic case corresponds to the
collision on the low curb at the exit from Turn 9. The

car accelerated from 103 to 185 km/h in 3 seconds,
with right wheels driving on a curb height of 2 cm
(Figure 6).

The third characteristic case corresponds to driving
along a straight section of the track between Turns 15
and 16. The car accelerated from 193 to 280 km/h in
10 seconds, moving along a straight trajectory without
entering the curbs (Figure 7).

4. Spectral analysis
of an experimental data

Due to the random nature of the front wing vibrations,
the best way to analyse it is using the spectral analysis
method [10].

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vol. 58 no. 5/2018 Analysis of Dallara T12 Race Car Front Wing Vibrations

Figure 8. Spectral power density of front wing vibrations fS(f).

Spectral analysis allows representing the energy dis-
tribution of oscillations in frequencies. The frequency
intervals with the highest energy indicate that the
oscillations with these frequencies occur most often,
or they have the greatest amplitude [10, 11].

The values of the vertical movements of the wing for
each characteristic case are expediently represented in
the form of energy spectra that distribute the energy
of these oscillations in the frequency domain.

These energy spectra, also called the spectral power
density of the oscillations, will make it possible to
clearly determine the frequency with which the wing
oscillations occur most frequently, or they have the
largest amplitudes.
Calculation of the spectral power density of oscil-

lations was performed using the calculation module
“sptool” of the MATLAB software [12, 13].

The energy spectrum of the oscillations was con-
structed by the fast Fourier transform (FFT) method.
Spectral power density graphs of the Dallara T12
racing car’s front wing vibrations for all three charac-
teristic cases are presented in Figure 8.
To display the spectral power density of the wing

vibration S(f) on a scale convenient for a visual per-
ception, each value of the spectrum was multiplied
by the corresponding frequency f . Thus, in Figure 8
shows the spectrum of fS(f).
Analysing the spectrum, we can conclude that the

oscillations with frequencies close to 1 and 4Hz have
the largest energy in the first characteristic case. Also,
a significant part of the oscillation energy is located in
the region of 2 and 7Hz. The distribution of energy
over these frequencies is due to low-frequency oscil-
lations, with large amplitudes resulting from driving
on a high curb at low speed in the first characteristic
case.

In the second characteristic case, the oscillations
with frequencies close to 1 and 3Hz have the greatest
energy. However, in contrast to the first characteristic
case, in this spectrum there are no clearly distin-
guished frequencies with a high oscillation energy. A
significant amount of energy is concentrated in the
frequency range from 0 to 7Hz. Such a distribution
of energy over frequencies is due to a higher speed
of the car in comparison with the first characteristic
case as well as a low curb height.
In the third characteristic case, the highest energy

level has oscillations with frequencies close to 2.5Hz.
Also, a large amount of vibration energy is concen-
trated in regions 1 and 7.5Hz. The remaining energy
is distributed in the range from 0 to 20Hz. Driv-
ing with a high speed along the straight sections of
the race track leads to a decrease in the amplitude
of the oscillations and an increase in their frequency.
The energy of the oscillations is uniformly distributed
throughout the frequency domain, with the excep-
tion of isolated peaks. This trend is manifested due
to increased high-frequency vibrations of the engine
and transmission as well as the occurrence of auto-
oscillations of the wheels caused by errors in their
balancing [14].
To estimate the probability of the resonance of

the Dallara T12 front wing, a modal analysis of its
finite element model was performed. The frequen-
cies of the first ten forms of its own oscillations
were determined. The lowest natural frequency corre-
sponding to the first mode of oscillation was 21 6Hz,
which significantly exceeds the frequencies obtained
as a result of spectral analysis of experimental stud-
ies. In this regard, we can conclude that on the front
wing of Dallara T12 race car, the occurrence of reso-
nance is unlikely.

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P. A. Sorokin, K. S Khryakov, M. Gommers Acta Polytechnica

5. Conclusions
The data obtained as a result of the spectral analysis
of three characteristic cases of the Dallara T12 racing
car’s front wing vibrations give a clear idea of the
characteristics of the wing oscillations while driving
the car along the track.
The use of these results in carrying out the CFD

analysis or blowing in the wind tunnel as the initial
data for the formation of vibrational disturbances
will allow investigating the effect of vibrations of the
race car aerodynamic elements on the level of the
downforce.
The results of the modal analysis of the finite el-

ement model of the Dallara T12 racing car’s front
wing shows that lowest natural frequency of the wing
significantly exceeds the frequencies obtained as a re-
sult of spectral analysis of experimental studies. In
this regard, we can conclude that an occurrence of a
resonance is unlikely for this wing. However, when
designing new racing cars, it is advisable to check a
possibility of a resonance of all aerodynamic elements,
which generate downforce.

References
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on the performance of the Grand Prix racing car”,
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[2] J. R. Jagadeep, G. Mayank, “Finding the optimum
angle of attack for the front wing of an F1 car using
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29 – 34, Greece, 2006.

[3] V. D. Berg, “Aerodynamic interaction of an inverted
wing with a rotating wheel”, Southampton, 2007.

[4] K. S. Khryakov, “Problems of the efficient operation
of race car aerodynamic elements”, Tidings of the Tula
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196, Russia, 2014.

[5] T12 2012 spare parts catalog, Dallara automobili, 2011.
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car”, Bologna, 2013.

[7] J. Katz, “Race car dynamics: designing for speed”,
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[8] K. S. Khryakov, P. A. Sorokin, “Research of the
shapes and natural frequencies of the Dallara T12 race
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[9] T12 2012 aerobook, Dallara automobili, 2012.
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[11] A. B. Sergienko, “Digital signal processing”,
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[12] K. Chen, A. Giblin, A. Irving, “Matlab in
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[13] Yu. Lazarev, “Modeling of processes and systems in
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[14] W.F. Milliken, “Race car vehicle dynamics”,
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	Acta Polytechnica 58(5):308–314, 2018
	1 Introduction
	2 Preparation for experimental research
	3 Experimental research
	4 Spectral analysis of an experimental data
	5 Conclusions
	References