The present invention relates to an airborne craft consisting of a propeller capable of being driven by a drive source and a skeleton body by which the drive propeller is supported in such a way as to be free to move.

The object of the present invention is in the first place to propose an airborne craft of the kind referred to above which has the ability to return to its starting point, like a boomerang, after having described a circular course on its flight through the air.

Said object is achieved by means of an airborne craft in accordance with the present invention which is characterized essentially in that a brake rudder attached to the skeleton body, which brake rudder is mounted coaxially in relation to said drive propeller is so arranged as to be rotated relative to i±e drive propeller when the craft is driven through the air, so that the brake rudder controls the shaft about which the drive propeller is rotated and generates lift for the craft.

The invention, which is capable of application for both civilian and military purposes, is described below in the form of a toy, in conjunction with which reference is made to the accompanying drawings, in which

Fig. 1 shows an airborne craft in a state ready for launching, with a "charged" drive source; Fig. 2 shows the craft viewed from above at an angle;

Fig. 3 shows the craft viewed from below at an angle;

Fig. 4 shows a part of the craft; Fig. 5 shows in diagrammatic form the propellers of the craft in a sectional view;

Fig. 6 shows a variant of an airborne craft with an internal combustion engine; and

Fig. 7 illustrates the possible course of the craft in diagrammatic form with the distances concerned.

The airborne craft 1 illustrated in the drawings in Figs. 1—5 consists of a skeleton body 2 which is preferably capable of being constructed easily from a number of frame components, such as- a number of tubes 3, 4, rods or similar, which are capable of being connected together with an upper and a lower part 5, 6 of the body, which skeleton body supports a propeller 8 capable of being driven by a drive source 7 in such a way as to be free to move. In accordance with the invention a brake rudder 9 is attached to said upper part 5 of the skeleton body or to some other appropriate part of the skeleton body 2 and is supported coaxially in relation to said drive propeller 8 on its under side 8A. The brake rudder 9 extends, when viewed in the radial sense in relation to the axis of rotation of said propeller, outside the drive propeller 8, that is to say it extends beyond the extreme end parts 10, 11 of the drive propeller. Said so—called brake rudder 9 is so arranged as to be rotated relative to the drive propeller 8 when the airborne craft 1 is driven through the air.

The drive propeller 8 and the brake rudder 9 exhibit preferably an essentially plane under side 8A and 9A, 9B, and the drive propeller 8 preferably exhibits a wing profile with an upper side 8B which is in the form of a curve, preferably with an essentially even curved shape, that is to say the propeller 8 reduces in thickness from its central area 8 ^" * towards its side edges 8 ² , 8 ³ . The drive propeller 8 exhibits at least two evenly distributed drive propeller parts 8 ^A , 8 ^B projecting from the axis of rotation 13 of the hub in a direction away from a common hub 12 in an essentially radial sense and at a certain angle A, preferably approximately 5°, in relation to the brake rudder Said parts 8 ^A , 8 ^B of the drive propeller are preferably so arranged as to be capable of adjustment to a desired angle B such that said parts 8 ^A , 8 ^B are inclined at the desired angle of inclination B between their respective under side 8 and a horizontal plane 14 when the craft 1 is held in an upright position with its propeller shaft 13 extending vertically. An appropriate angle of rotation of the blade is between approximately 15 and 20°. The parts 8 ^A , 8 ^B of the drive

propeller can, for example, be locked in a desired, set angular position by means of locking screws 15 which are accommodated in threaded holes 16 on the inner ends 17, 18 of the parts, so that the screws 15 can lock the parts 8 ^A , 8 ^B of the drive propeller to a rigid shaft 19, 20 which projects radially from the hub 12, which shaft 19, 20 and the part 8 ^A , 8 ^B of the drive propeller are accommodated for a certain distance inside a matching accommodating space 21.

The brake rudder 9, which similarly consists of at least two blades, exhibits a recessed part 22 along its upper side 9C, which brake rudder, when viewed along the radial extent of the propeller, is at least matched by the radial extent of the drive propeller. The two blades 8, 9 are thus so arranged as to extend alongside one another and at a not excessively great distance from one another. Away from said recessed part 22, when viewed in a radial sense from the skeleton frame 2, the brake rudder 9 exhibits brake rudder parts 9 ^A , 9 extending in a radial direction from its longitudinal axis 23. The brake rudder 9 appropriately tapers at its respective ends 24, 25 in a curved fashion so as to form an arrow—shaped tip with a rounded outer part.

Said brake rudder 9 is also capable of angular adjustment relative to its associated supporting shaft 26, 27, so that said brake rudder parts 9 ^A , 9 ^B are adjusted to a desired brake angle C in relation to an imaginary horizontal plane 28 which extends through the part 29 of the rotating shafts of said parts when the craft 1 is held in the aforementioned upright position, as illustrated in Figs. 2 and 3. The appropriate angle C can be varied between 50 and 120°, for example, in conjunction with which the optimum angle C appears to be approximately 50°, that is to say the craft 1 will describe its maximum course at this angle. Said adjustability may be afforded, for example, by means of connecting joints 32, 33 between said supporting shafts 26, 27 and propeller rotating shafts 30, 31, which are securely attached to the respective brake propeller parts 9 ^A , 9 ^B and extend closely along said recessed part 22 in the brake rudder 9. Said connecting

joints 32, 33 may, for example, consist of sleeves or similar telescopic joints made of a plastics material, for example, which allow a part of each of said propeller rotating shafts 30, 31 to be accommodated for the purpose of clamping same securely in the desired angular position.

The tubes 3, 4, etc., which form said skeleton body 2 can be capable of attachment to the respective upper and lower part 5, 6 of the skeleton body preferably by being capable of being accommodated with their respective ends 3A, 3B, 4A, 4B by appropriate connection sleeves 34, 35, 36, 37 which project from the associated part 5, 6 of the body.

In those cases in which the drive source 7 consists of a number of loop—shaped elastic bands 7A, 7B or similar elastic elements, appropriate attachments 38, 39 can be supported by the respective part 5, 6 of the body. One 39 of said two attachments 38, 39 is capable of being attached to the drive propeller 8, and preferably of being securely connected to the rotating shaft 13 of the hub, whilst the other attachment 38 is rigidly connected to the lower part 6 of the body. Said attachment 39, which is connected to the shaft

13 of the drive propeller, which shaft is in turn accommodated by a channel 40 running transversely through the hub 12, is situated at one end 41A of a movement—transferring component 41, whilst its other end 41B exhibits a driver 42, for example in the form of a hook, which is capable of being caused by the rubber band 7A, 7B in question or by some other drive source, against the effect of the force exerted by a compression spring 44 acting between the hub 12 and an enlarged contact part 43 on the driver 42, to be moved into a position in which it is able to interact with the hub 12. In said interaction position I, which is indicated by solid lines in Fig. 4, it is possible for stored energy, for example, to be transferred from the rubber bands, etc., 7A, 7B to the hub 12, thereby producing driving movement in the hub 12, and also to the drive propeller 8. The effective force of the spring 44 is so arranged as to exceed the force F which the drive source 7, 7A, 7B exerts against said hub—connected attachment 39 when the drive

source 7 adopts its inactive position, that is to say when the rubber bands 7A, 7B are kept slack. The spring 44 will then endeavour to push the driver 42 in a direction away from the hub 12 and out of its engaged position I with the hub 12 towards a released position II, in which position II the drive propeller 8 is permitted to rotate freely. This is desirable, since it is not wished for the drive propeller 8 to be stopped or to change its direction of rotation during the period for which the craft is flying, in so doing interfering with its intended function. When it is wished to charge the drive source 7 consisting of rubber bands 7A, 7B, it is first necessary to push the driver 42 towards the hub 12 so that it comes into said interaction position I, whereupon the drive propeller 8 is caused to rotate in the direction of charging 45, that is to say in the opposite direction to the intended driving direction 46 of the propeller, at the same time as the driver 42 is pushed down. In this way the rotating movement is transferred to the attachment 39 and the rubber bands- 7A, 7B via the driver 42. Once the rubber bands 7A, 7B have been caused to rotate through a sufficient number of revolutions and have thus been shortened to such a degree that they themselves endeavour to pull down the attachment 39 in the direction of the arrow 46, there will no longer be any need to push down the driver 42 manually whilst continuing to wind up the rubber band motor 7.

The following Tables relate to two drive propellers 8 which exhibit different blade inclination angles B, of approximately 20° and approximately 15° respectively, in conjunction with which reference is made to Fig. 7, in which the various values indicated in the Tables are marked along the intended calculated course of the craft between its starting point 0 and its landing point, which in the best possible case is the same as the starting point 0, which shall be understood to denote that the distance A is 0 metres if the craft is so arranged as to return to its starting point 0 after having described a circular course, as shown by the arrows.

Table 1: Drive propeller with blade inclination angle (B) of approximately 20°.

°c DCm) E(m) A(m) hCm) h' UTi)

50° 15 8 0 2 1'5

70° 13 6 0 2 1'5

90° 8 5 0 1 0-5

110° 2 2 0 0'5 0-25

Table 2: Drive pi "opeller with bl, -de inc angle (B) of approximately 15°.

°C DCm) E(m) A(m) h(m) h-(m)

50° 15 10 12 2 0

70° 13 8 2 3 0

90° 10 7 0 3 1'5

110° 3 3 0 1 0'5 The drive propeller arrangement outlined above functions in accordance with two main principles in order to cause the airborne craft 1 to fly and to return to its starting point; i.e.:

1. A drive effect produces a curved course through interaction between the drive propeller 8 and the brake rudder

9. In the event of the drive propeller 8 being so arranged as to rotate in an anti—clockwise direction 47, viewed from above the craft, the brake rudder 9 together with the rest of the craft will be caused to rotate in a clockwise direction 48, which is the case in the illustrative embodiment described above and shown in the drawings. The craft 1 will accordingly fly along a circular course in a clockwise direction, as shown in Fig. 7. In the event of the drive propeller 8 being so arranged as to rotate in a clockwise direction 48, the brake rudder 9 will be caused to rotate in an anti—clockwise direction 47, and the craft will fly along a circular course in an anti—clockwise direction 47.

2. A pendulum effect, achieved through the mass of the craft. In the event of the drive source 7 consisting of rubber bands 7A, 7B, these are designed so that the craft 1 will fly and return to its starting place after the energy of the rubber bands is spent. The craft 1 is thus imparted with precisely the pulse

effect required for this purpose, and by selecting precise angles B, C for the drive propeller 8 and the brake rudder 9, and by inclining the craft 1 at a certain angle D in relation to the horizontal plane, it is possible for the craft to fly along a circular course and also to return to the starting point of the craft.

The brake rudder 9, which can be adjusted to the desired angle C, as shown in Fig. 5, should be as light and strong as possible, with a suitable material being plastic, light alloy or some other lightweight wooden material, this requirement being equally applicable to the drive propeller 8.

The brake rudder 9 functions as a propeller when it is set to an angular adjustment C at an advantageous angle of approximately 50°, for example, which propeller helps to pulse the craft 1 and thus to maintain it in its initial position, as shown in Fig. 1 by an angle of inclination D° of approximately 60°, for example, so that the craft can fly over a maximum distance D(m) from the starting place and can then return to the starting place.

The brake rudder 9 with its angular adjustment C of approximately 110° causes it to function as a negative propeller, which removes the pulse effect and influences the craft in such a way that its angle of inclination D° is changed rapidly from its initial position, and which causes the craft 1 to fly over a reduced distance DCm) but still to return to its starting place. It is important to point out that, if the brake rudder 9 is situated above the centre of gravity of the craft, it will cause the craft to move downwards, and vice versa in the opposite position.

Approximately 38% of the total mass of the craft can be present in the drive propeller 8, and the centre of gravity of the craft should preferably be situated in the area of the attachment 39 or above same.

It is also very important for the drive propeller 8 not to be influenced by considerable friction in its mounting on the skeleton body 2, since any increase in friction will mean that more energy must be supplied in order to drive the craft 1 so that

it will fly along the desired course and over the desired distance.

An increase in the number of rubber bands will mean that the centre of gravity of the craft is lowered or changed in some other way.

Suitable bearings, preferably good quality roller bearings, should thus be used as the bearing for the drive propeller 8. In order to reduce the risk of damage by the craft 1, the edges of the propellers may be rounded.

The craft 101 shown in Fig. 6 differs from the previously described craft 1 primarily with regard to the design of its drive propeller 108 and body 102 and the choice of power source

107.

The drive propeller 108 exhibits three blade parts

108 ^A , 108 ^B and 108 ^c which increase in width in the direction of the middle of the craft. The function of this craft 101 is the same as that of the previously described craft 1, except for the fact that the craft 101 can fly for longer distances thanks to the presence of the motor 107 powered by liquid fuel.

The invention is not restricted to the illustrative embodiments described above and illustrated in the drawings, but may be modified within the scope of the Patent Claims without departing from the idea of invention.