Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Hovercraf t
The invention relates to a hovercraft with at least one lift
fan for producing an air cushion and at least one thrust
unit, which acts on the top surface of the craft, where the
thrust unit serves to propel the craft and/or control its di-
rection, and both the lift fan and the thrust unit have at
least one airscrew that is driven by means of a motor and
generates an air current.
All known hovercraft designs are very heavy. Moreover, the
weight is distributed unevenly over the craft as a result of
its design or operation. In this type of craft, however, uni
form weight distribution is of particular importance, as a
poorly balanced hovercraft can easily transition from an
ideal hovering state to unsteady behaviour. Uneven weight
distribution must then be corrected by a complex and heavy
ballast system.
In known hovercraft of the type described, particularly rela
tively small ones, the thrust unit is often mounted in rigid
fashion in the stern region of the deck and the weight con
centrated there.
The rigid thrust unit of this design is equipped with one or
more rudders for steering, with which the generated air cur-
rent must be deflected, this entailing high frictional
losses. Another design involves several rigid thrust units,
which control the direction of travel by individually con-
trolling the airscrew rotational speed of each individual
thrust unit. In both hovercraft designs, the motor is close
to the rigidly mounted thrust units) and thus concentrates
even more weight in the stern region of the hovercraft. In
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order to achieve the required uniform weight distribution in
this case, a ballast system, such as a tank for holding bal
last water, must be provided in the bow region. This further
increases the weight, gives the hovercraft very high inertia
and reduces the useable space.
In order to manoeuvre, a torque must be induced in the known
hovercraft with a rigid thrust unit. This torque steers the
craft in the desired direction. In this respect, the manoeu-
viability is similar to that of a ship. Due to the high iner
tia of the hovercraft and the low resistance of the air to
the motion of the craft, however, turning can only be stopped
by applying a torque in the opposite direction. The high in
ertia of the craft again has a disadvantageous effect in this
context.
The above designs also have disadvantages in terms of fluid
dynamics, particularly during forward travel, as the motor
provided in the vicinity of the thrust unit hinders the flow
of air on the intake side of the airscrew in this case. In
addition, a mechanical driveline that links the drive motor
to the air screw must be provided. It consists, for example,
of shafts, joints, gears, clutches, etc. that also add to the
weight of the craft and thus increase its inertia.
Among larger hovercraft, such as large hovercraft ferries,
there is a known design with thrust units that are designed
to pivot about a vertical axis. In this case, the air current
can be turned in the desired direction in order to steer. The
pivoting thrust units are referred to below as "pivoting
units". They have drive shafts arranged parallel to, or even
along, the vertical pivoting axis of the pivoting unit. The
drive shaft is driven by a separate motor via an angular
gearbox or the like and, in turn, drives the airscrew via
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_ another angular gearbox. The motors and additional angular
gearboxes increase and concentrate the weight in the area of
the pivoting unit.
In order to reduce the weight, the drive energy of a single
motor could be fed to several pivoting units. However, this
would entail the disadvantage that the drivelines would
greatly restrict the useable space.
Depending on how many pivoting units are provided and where,
an additional ballast system must also be provided in this
design in order to achieve uniform weight distribution
throughout the craft.
In relatively small hovercraft, the use of heavy pivoting
units with separate motors is dispensed with due to the great
weight and the problems with weight distribution.
In order to decelerate the known hovercraft, it is necessary
to reverse the direction of the air current. For example,
this can be achieved in the known fashion by reversing the
sense of rotation of the airscrew, this having the disadvan-
tage that the airscrew must be first brought to a standstill
and then accelerated in the opposite rotational direction.
Another solution provides for the adjustment of the airscrew
blades, where the air current is reversed while the airscrew
continues to rotate in the same direction. This, however, re-
quires a mechanically complex adjusting mechanism to adjust
the airscrew blades.
The object of the invention is to design a hovercraft that
can be operated with a little expenditure of energy and has
good manoeuvrability, good space utilisation and a high pay-
load relative to its weight.
According to the invention, the object is solved in that the
motor takes the form of an electric motor located directly on
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the airscrew, and in that at least one central energy genera-
tor, which supplies the electric motor with drive energy via
an energy line, is provided in order to generate the electri-
cal drive energy required by said electric motor.
This measure creates a hovercraft, the useable space of which
is not restricted by a driveline and which therefore has par-
ticularly good space utilisation. The energy line is provided
in the form of an electrical line, which feeds the drive en-
ergy to the electric motor. It is considerably lighter than a
mechanical driveline and is laid such that it does not re-
strict the useable space of the hovercraft.
As a result of technical advancements in the field of elec-
trical machines and controllers, electric motors and genera-
tors are available that have a very high power density rela-
tive to their weight. Only this new drive technology makes it
possible to provide an electric motor directly on the air-
screw. With this design, the thrust unit is particularly
light and requires only little installation space.
As a result of this new method, thrust units can be mounted
at various locations on the hovercraft, such as on the roof
of the hovercraft, which is favourable in terms of fluid dy-
namics. The previous design problems, namely uniform weight
distribution throughout the craft, can now easily be solved.
Steering by means of a rudder, and the associated efficiency
loss in propulsion, can be dispensed with. The ballast system
is only required to compensate for unevenly distributed cargo
and can be of a much smaller and lighter design. The central
energy generator can be positioned at a favourable location.
For example, it is possible to compensate for a slight imbal-
ance in a hovercraft provided with two, light stern pivoting
units by placing the energy generator in a suitable position
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to act as counter-ballast. The hovercraft thus has less iner-
tia and is easy to manoeuvre. In addition, the payload and
useable space of the craft are increased.
5 With the proposed invention, the propulsion power can be con-
trolled very easily by regulating the rotational speed of the
airscrew. As the airscrew is driven by an electric motor,
there is no need for complex and very heavy gears to change
the rotational speed, which can be controlled in infinitely
variable fashion and very precisely. In addition, the air-
screw need not be designed with adjustable airscrew blades to
regulate the propulsion power.
Decelerating the hovercraft by reversing the direction of the
air flow is also possible with the known methods when using
electric motors to drive the airscrew, namely by reversing
the sense of rotation of the airscrew or adjusting the air-
screw blades while the sense of rotation of the airscrew re-
mains the same. With the new hovercraft, however, decelera-
tion can also be simply performed by rotating the pivoting
unit through 180° and the complex methods described above can
be dispensed with. No mechanical driveline has to be pivoted
at the same time and pivoting can thus be achieved with very
little design effort.
In order to prevent the thrust of the pivoting unit from
turning the hovercraft during pivoting, a pair of pivoting
units or a multiple number of pivoting unit pairs are advan-
tageously provided. One pivoting unit of a pair then pivots
through 180° about its vertical axis in the one pivoting di-
rection and the other by 180° in the opposite pivoting direc-
tion. The torques generated by the air current during pivot-
ing act in opposite directions and cancel each other out. The
hovercraft does not turn. Pivoting can take place at the
maximum rotational speed of the airscrew. It is thus possible
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to switch from propulsion to deceleration in a very short
time.
The energy generator expediently has a modern generator
driven by a drive motor. The generator and the drive motor of
the energy generator are preferably combined in a compact as-
sembly, so that heavy and space-wasting drive elements for
connecting these two components can again be eliminated. The
energy generator is preferably the central energy supply unit
for all electric motors. It can be located anywhere on the
hovercraft. This allows extensive design freedom and thus
makes it possible to considerably increase the payload and
the useable space compared to known hovercraft.
The drive energy can be fed to the pivoting electric motor
via electrical sliding contacts, flexible cables or other
suitable means. In this way, a pivoting unit can be designed
to pivot through more than 360°.
The energy generator can have a compact drive motor in the
form of a turbine linked to a modern generator. The turbine
is considerably lighter than a diesel engine, for example.
Unlike a diesel engine, which drives the airscrew directly,
it can also be continuously operated under optimum condi-
tions. This means that it can operate at the most favourable
rotational speed and under the most favourable torque load.
Of course, a simple combustion engine, such as a two-stroke
or four-stroke piston engine, for an advantageous fuel can
also be used as a drive motor in a simple configuration.
In order to rapidly move the pivoting unit about its vertical
axis into a desired pivoting position, it is equipped with a
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separate pivoting drive. This is also expediently equipped
with an electric drive motor and a suitable mechanical ad-
justing device.
One configuration of the hovercraft has at least one pivoting
unit. It is used both to propel and steer the craft.
Two pivoting units are preferably provided, these being ar-
ranged in the direction of the lateral principal axis of in-
ertia of the hovercraft, as well as mirror-symmetrical to its
longitudinal principal axis of inertia. Due to its particu-
larly favourable distribution of weight to the sides, this
arrangement affords outstanding stability in the hovering
state. Due to the thrust impulse acting in the lateral prin-
cipal axis of inertia, the manoeuvrability is excellent and
particularly efficient for straight travel in a pivoting po-
sition parallel to the longitudinal principal axis of iner-
tia. In the manner of a motor vehicle with all-wheel steer-
ing, the hovercraft can travel straight ahead at an angle a
to its longitudinal principal axis of inertia. This makes it
possible to control the direction without having to steer the
hovercraft into the desired direction of travel, as with a
ship. Due to the fact that the craft need not be turned into
its direction of travel, nor this turning stopped by counter-
steering with a torque in the opposite direction, very good
manoeuvrability is provided, where the inertia of the craft
is not very noticeable. The hovercraft can be precisely
steered and requires little room to manoeuvre.
Another configuration is expediently equipped with two rigid
thrust units, which are exclusively used to provide propul-
sion. In this case, at least one thrust unit is designed as a
steering unit, which is exclusively used for steering. This
special design has the advantage that manoeuvring is handled
via a single steering unit, whose pivoting position deter-
mines the direction of travel.
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In the design with just one steering unit, it is mechanically
favourable for the steering unit to be mounted on the stern
in vertically pivoting fashion above the longitudinal princi-
pal axis of inertia, as the induced thrust vector of the
steering unit can generate a maximum torque for directional
control.
The steering unit is equipped with a pivoting drive for easy
pivoting about its vertical axis. It is also expediently pro-
vided with an electric drive motor and a suitable mechanical
adjusting device.
In an alternative configuration of the hovercraft, both the
stern and the bow are provided with at least one pivoting
unit. This special design permits the generation of maximum
torques for directional control by both the stern pivoting
unit and the bow pivoting unit, which further improves ma-
noeuvrability. With this design, the hovercraft can again
travel straight ahead, in the manner of a motor vehicle with
all-wheel steering, at an angle a to its longitudinal princi-
pal axis of inertia. The pivoting units on the stern and bow
are preferably mounted above the longitudinal principal axis
of inertia.
The pivoting position of all of the pivoting and steering
units is preferably individually controllable. This permits
the greatest possible degree of variation for changing direc-
tion during a manoeuvre. The variety of pivoting positions
that the individual pivoting units can take up relative to
one another should, however, be reduced to those that are ad-
vantageous for steering the hovercraft. This can be achieved
by mechanical means or simply by program-assisted control of
the pivoting drives. In this way, the driver can easily con-
trol the hovercraft.
The thrust units designed as pivoting and/or steering units,
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as well as the lift fan, are all preferably driven individu-
ally at the desired rotational speed of the airscrews. How-
ever, the possible rotational speed combinations of the indi-
vidual airscrews relative to one another should be reduced to
those combinations that are advantageous for steering the
hovercraft, so that the driver can easily control the craft.
To this end, a program-assisted controller can again be pro-
vided that links the allocation of the individual rotational
speeds of several thrust or steering units.
In order to enable automatic correction of the pivoting posi-
tion of the pivoting and/or steering units, a crosswind gauge
can be provided that records the crosswind component meas-
ured. This can be analysed for the purpose of automatically
adjusting the pivoting position of the pivoting and/or steer-
ing units required for straight travel, or, in the case of
rigid thrust units, influence the required thrust distribu-
tion or the rudder position.
Another advantage is the fact that the hovercraft according
to the invention can very easily be steered with the help of
a program-assisted autopilot.
The airscrew of the pivoting and/or steering unit is advanta-
geously shrouded. The airscrew blades are preferably mounted
on the airscrew hub in rigid fashion.
An example of the invention is illustrated below in the draw
ing and explained in detail based on the figures. The figures
show the following:
Fig. 1 A top view of a configuration of the hovercraft with
two pivoting units arranged in the direction of the
lateral, and mirror-symmetrical to the longitudinal
principal axis of inertia,
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Fig. 2 A side view of the hovercraft according to Fig. 1,
Fig. 3 A top view of the hovercraft according to Fig. 1
during straight travel at an angle a to the longitu-
5 dinal principal axis of inertia,
Fig. 4 A top view of the hovercraft according to Fig. 1
during a turn about a vertical axis,
10 Fig. 5 A perspective view of another configuration of the
hovercraft with a thrust unit designed as a steering
unit for directional control,
Fig..6 A top view of a configuration of the hovercraft, the
stern and bow of which are both provided with a piv
oting unit,
Fig. 7 A top view of the hovercraft according to Fig. 6.
According to Fig. 1, hovercraft 1 comprises a lift fan A for
producing an air cushion and two thrust units designed as
pivoting units 2 and 3, which act on the top surface 4 of the
craft. Pivoting units 2 and 3 can pivot about their vertical
axes 2a and 3a. They are used for the propulsion and direc-
tional control of the craft and are arranged both in the di-
rection of the lateral principal axis of inertia x-x of the
hovercraft, as well as mirror-symmetrical to its longitudinal
principal axis of inertia y-y. Lift fan A and the thrust
units each have airscrews (not shown), each of which is
driven by one of motors 5, 6 and 21 and generates an air cur-
rent. Motors 5, 6 and 21 are located directly on the air-
screws. In order to generate the drive energy required by mo-
tors 5, 6 and 21, a central energy generator 7 is provided
that supplies motors 5, 6 and 21 with drive energy via energy
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lines 5a, 6a and 21a. Pivoting units 2 and 3 can pivot about
vertical axes 2a and 3a by means of a pivoting drive not
shown here. Motors 5, 6 and 21 are designed as electric mo-
tors El, E2 and A and energy lines 5a, 6a and 21a as electri-
cal lines L1, L2 and L3. These are considerably lighter than
a mechanical driveline. They are only shown schematically
here. As electrical lines L1, L2 and L3 require only very
little space and can be laid in almost any configuration, the
useable space of the hovercraft is hardly restricted at all.
Due to its particularly favourable distribution of weight to
the sides, the arrangement of the pivoting units according to
Fig. 1 affords outstanding stability in the hovering state.
Due to the thrust impulse acting on the lateral principal
axis of inertia x-x, the manoeuvrability is excellent and
particularly efficient for straight travel when in a parallel
pivoting position. In the manner of a motor vehicle with all-
wheel steering, the hovercraft can, as shown in Fig. 3,
travel straight ahead at an angle a to its longitudinal prin-
cipal axis of inertia y-y. As shown by the arrow drawn around
vertical axis 8 in Fig. 4, it is possible to turn the hover-
craft in its current hovering position by making a pivoting
motion, e.g. by turning pivoting unit 3 through 180°.
The useable space of the hovercraft is not restricted by a
driveline and the space utilisation is therefore particularly
good.
Energy generator 7 is positioned at the centre of the hover-
craft and equipped with a drive motor B and a generator G,
which serves to generate the electrical drive energy for
electric motors E1 and E2. The weight distribution is very
uniform with this arrangement. Energy generator 7 is combined
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wi th drive motor B and generator G to form a compact assem-
bly. This can be optimally positioned when designing a hover-
craft and the useable space thus maximised.
In the present configuration, compact drive motor B takes the
form of a turbine that is lighter and smaller than a compara-
bly powerful piston engine.
The configuration of the hovercraft according to Fig. 5 has
two rigid thrust units 10 and 11, which are exclusively used
to provide propulsion. An additional thrust unit is provided
in the form of steering unit 14, which, as indicated by arrow
14a, can pivot about its vertical axis 13. It is exclusively
used for steering the hovercraft. This special design has the
advantage that manoeuvring is handled via a single steering
unit 14, whose pivoting position determines the direction of
travel. A pivoting drive (not shown) is again provided here
to pivot steering unit 14.
In the design with just one steering unit 14, it is mechani
cally particularly favourable for steering unit 14 to be
mounted on the stern 15 above the longitudinal principal axis
of inertia y-y, as the induced thrust vector V of the steer
ing unit can generate a maximum torque for directional con
trol.
In an alternative configuration of the hovercraft, the stern
15 and the bow 16 are each provided with one pivoting unit 17
and 18. This special design permits the generation of maximum
torques for directional control by both the stern pivoting
unit 17 and the bow pivoting unit 18, which further improves
manoeuvrability. With this design, the hovercraft can again
travel straight ahead, in the manner of a motor vehicle with
all-wheel steering, at an angle a to its longitudinal princi-
pal axis of inertia. The pivoting of stern pivoting unit 17
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through 90° and of bow pivoting unit 18 through minus 90°,
for example, also makes it possible with this configuration
to turn the hovercraft about vertical axis 19, precisely at
its current hovering position.
Pivoting units 17 and 18 on stern 15 and bow 16 are mounted
above the longitudinal principal axis of inertia y-y. Bow
pivoting unit 18 is smaller than stern pivoting unit 17. It
primarily serves the purpose of steering the craft. Stern
pivoting unit 17 is essentially provided to propel the hover-
craft.
The airscrew of the pivoting and/or steering unit is advanta-
geously provided with a shroud 20.
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Hovercraf t
List of reference numbers
1 Hovercraft
2 Pivoting unit
2a Vertical axis
3 Pivoting unit
3a Vertical axis
4 Top surface of the craft
5 Motor
5a Energy line
6 Motor
6a Energy line
7 Energy generator
8 Vertical axis
10 Rigid thrust unit
11 Rigid thrust unit
13 Vertical axis
14 Steering unit
14a Arrow
15 Stern
16 Bow
17 Pivoting unit (stern)
18 Pivoting unit (bow)
19 Vertical axis
20 Shroud
21 Motor
21a Energy line
A Lift fan
B Drive motor
E1 Electric motor
E2 Electric motor
G Generator
L1 Electrical line
L2 Electrical line
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L3 Electrical line
x-x Lateral principal axis of inertia
y-y Longitudinal principal axis of inertia
a Angle
5 V Thrust vector
