Aeroacoustics - SCHUBERTH C3 Manuel

D. THE HELMET
6. AERODYNAMICS
All SCHUBERTH motorcycle and racing helmets are developed and
optimised in SCHUBERTH's own wind tunnel under scientifi c, precisely
defi ned conditions.
The C3 is specifi cally designed for a touring or sports-touring riding
posture and remains stable in the air current. Even when travelling at
high speeds, the C3 generates practically no upward lift. Other
characteristics of the C3 are improved air resistance and excellent
directional stability. In addition, the buffeting often experienced at
high speed on an unfaired motorcycle is signifi cantly reduced.
Note:
Please note that the strong eddy currents that can occur at
the edges of the wind shadow with faired motorcycles due to
the fairing can have a considerable effect on the aerodynamic
characteristics of a helmet.

7. AEROACOUSTICS

We have paid a lot of attention to improve the acoustic properties of
the C3 without a reduction of comfort. Various features developed
in SCHUBERTH's wind tunnel (such as special adaptation of the wind
defl ector in the chin area and the shape of the acoustic collar) as well
as the choice of special materials eliminates draughts and makes
the helmet quieter*. This enables relaxed riding – especially on long
journeys – and enhances concentration.
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A quiet helmet is characterised by low wind noise. Wind noise arises
through turbulent swirling of the air that fl ows around the helmet. The
turbulence generates local pressure fl uctuations, which are detected
inside the helmet as noise (so-called pseudo noise). Only the wearer
of the helmet hears this noise. With most motorcycles and helmets,
engine noise is covered up by this wind noise from around 100 kph
upwards.
* Acoustic values can vary depending on type of motorcycle, fairing design, riding
posture and body size.
Caution:
The actual road speed can be underestimated slightly as
a result of the acoustic optimisation of the helmet and the
accompanying low wind noise. I.e. don't rely on your sense of
hearing to judge road speed – check your speedometer.
Note:
Please note that with faired motorcycles strong eddy currents
occur at the edges of the wind shadow. This can considerably
reduce the aero-acoustic performance of the helmet. The fairing
of the motorcycle should be adapted so that the departing
turbulence does not strike the bottom surface of the helmet.
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