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EP 0 577 160 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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11.12.1996 Bulletin 1996/50 |
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Date of filing: 25.03.1993 |
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Jumping ski
Sprung-ski
Ski de saut
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Designated Contracting States: |
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AT FR |
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Priority: |
30.03.1992 NO 921226
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Date of publication of application: |
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05.01.1994 Bulletin 1994/01 |
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Proprietor: Kolset, Einar |
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N-4045 Hafrsfjord (NO) |
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Inventor: |
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- Kolset, Einar
N-4045 Hafrsfjord (NO)
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Representative: Bjellman, Lennart Olov Henrik et al |
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DR. LUDWIG BRANN PATENTBYRA AB
Box 1344 751 43 Uppsala 751 43 Uppsala (SE) |
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References cited: :
DD-A- 270 011 FR-A- 2 565 836
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DE-A- 3 236 016
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] This invention relates to the curve of the upper side of jumping skis being formed
like a wing profile.
[0002] In ski jumping the V-style has found favour relative to the "classical" jumping style.
[0003] An important reason for this success is that with the V-style the skis cover a larger
area against the wind. This means that more air molecules must be displaced by the
passage of the skis through the air, such that the potential lift can be increased.
[0004] Another advantage with the V-style is that the skis are separated with a larger distance
such that the moment of lateral stability increases with the larger arm.
[0005] "Classical" jumping skis are still used in V-style jumping. These skis are characterised
by a rectangular cross-section which is not, however, aerodynamically favourable.
[0006] A German document DD-A- 270 011 discloses a jumping ski which is modified to guarantee
an improved take-off and a longer jump as well as a higher stability of flight in
an ordinary ski jump. This is obtained by giving an almost convex form to the lower
surface beginning at the tip of the ski. This form is then continuously changed along
the jumping ski into a more or less concave cross section profile at the ski contact
point to the running jump track.
[0007] The purpose of the invention is to give the cross-section of the jumping skis an
aerodynamic shape, akin to an aeroplane wing profile, in order to reduce drag and
to increase lift. The invention is set out in claim 1. Advantageous embodiments of
the invention are featured in dependent claims 2 and 3.
[0008] The invention is further explained by reference to figures 1 to 3.
Fig 1
a) shows a cross-section through a rectangular classical jumping ski,
b) shows a cross-section through a wing profile formed jumping ski, in accordance
with the invention, and
Fig 2
a) shows a plan view of the left ski,
b) shows all the cross-sections (seen from the front) of the left ski in accordance
with the invention, and
Fig 3
a) shows the dihedral angle of the skis in the in-flight position,
b) shows a plan view of the V-shape of the skis in the in-flight position.
[0009] Fig 1a) shows a cross-section through a normal "classical" jumping ski with 6 longitudinal
running grooves.
[0010] Fig 1b) shows a cross-section through a wing profile formed jumping ski where the
wing profile is pointing inwards towards the centre line (S).
[0011] Fig 2a) shows the plan view of the left ski. The relative wind is indicated by arrows
at an angle of 20° to the inside of the ski. The ski jumping boots are fastened to
the ski on a flat part; in plan view, approximately a skew rectangle. Apart from this
flat part (line 6 in fig 2b), the outside edge of the skis have a constant height
of ca. 5mm (the trailing edge), whereas the inside has a thickness (height) which
varies from ca. 5mm (line 1 in fig 2b) to ca. 12mm (line 5 in fig 2b).
[0012] Fig 2b) shows all the sections (profiles) through lines 0 to 6 in fig 2a).
Line 0 in fig 2b) indicates a stippled profile (wing profile) with a smaller angle
of attack. This is achieved by twisting the ski tip in towards the centre line (twisted
anticlockwise in the diagram). The skis still have normal "tension" where the centre
part lifts itself up from the base. In fig 2b) the left ski is loaded with weight,
making the centre part lie flat on the base.
A symmetric (normal) ski tip can also be used, especially such ski tips which have
a low height. The disadvantage that such a ski tip might create is turbulence in the
air stream because of too large angle of attack.
[0013] Fig 3a) shows the angle between the underside of the ski and the horizontal plane
in the direction of motion. This angle increases with the increasing distance between
the skis and has the dominant influence on lateral stability.
[0014] Fig 3b) shows the skis in the V-style in-flight position seen in plan view.
[0015] The angle of attack of a wing is the angle between the relative wind and the chord
line of the profile.
[0016] With normal elasticity and under stable flying conditions, the tip and the tail of
the ski will bend up, due to the lift, where the optimal wing profiles are formed
(with the top point at a position near 1/3 of the chord line).
1. A jumping ski, which has a cross-section with a flat base and longitudinal running
grooves and a smooth curved upper side, wherein the curve of the upper side is formed
like a wing profile, said wing profile pointing in towards a center line (S), whereby
the attack of the wing is the angle between the relative wind and the chord line of
the profile.
2. The jumping ski according to claim 1, characterized in that the tip of the ski is twisted towards said center line (S), to avoid turbulence
in the air stream because of too large angle of attack.
3. The jumping ski according to claim 1, characterized in that the upper side of the ski has a flat part being in a plan view approximately
a skew rectangle where the boots are to be fastened.
1. Ein Sprungski mit einem Querschnitt der eine flache Unterfläche und steuernde Längsnuten
und eine glatte gekrümmte Oberseite aufweist, dadurch gekennzeichnet daß die Krümmung
der Oberseite als ein Flügelprofil ausgebildet ist, welches Flügelprofil einwärts
gegen eine Mittellinie (S) gerichtet ist, wobei der Angriffsvinkel des Flügelprofils
der Vinkel zwischen dem Fahrtwind und der Sehne des Profils ist.
2. Sprungski nach Anspruch 1, dadurch gekennzeichnet daß die Skispitze gegen die Mittellinie
(S) gedreht ist, um Turbulenz im Luftstromen wegen zu grossem Angriffsvinkel zu vermeiden.
3. Sprungski nach Anspruch 1, dadurch gekennzeichnet daß die Oberseite des Skis einen
flachen Teil aufweist, der in Planansicht einen schrägen Paralelogram bildet, wo die
Skistiefel befestigt werden.
1. Un ski à sauter qui a une section avec une base plate et des rainures de guidage longitudinales
et une face supérieure unie courbée, caracaterisé en la courbe de la face supérieure
formant un profile d'aile, ledit profile d'aile pointant vers une ligne médiane (S),
oú l'attaque de l'aile est l'angle entre la vent relatif et la corde du profile.
2. Un ski à sauter selon le revendication 1, caracterisé en ce que le bout du ski est
tordu vers ladite ligne médiane (S), pour éviter de turbulence à cause d'un angle
d'attaque trop grosse.
3. Un ski à sauter selon le revendication 1, caracterisé en ce que la face supérieuere
du ski a une partie plate formant un parallélogramme oblique en vue en plan oú les
chaussures de ski sont fixées.