GB2246752A - Solar powered vehicle - Google Patents

Abstract

The vehicle is powered by a source of electromagnetic radiation directed towards it. It has a segmented parabolic shaped mirror composed of a parabolic shaped frame (1) (figure 1) which is used to support individual, flat mirror elements (figure 3). A central tower supports, at the focus of the mirror, a means of converting the energy of electromagnetic radiation to mechanical energy to propel the craft. This may be done directly by trapping the radiation and using it to heat air which propels the craft by means of a turbojet principle (figure 8/1), or indirectly by using radiation collectors to first convert the energy of the radiation to electrical energy which is then used to power an electric motor which drives a propeller (figures 5 to 7 inclusive). Alternatively, the craft is propelled by the neutrons released when pellets of deuterium/ tritium placed at the focus of the mirror are imploded by pulsed laser radiation. The mirror frame (1) is built up of carbon fibre reinforced resin rods, and mirror elements of polyester sheet of trapezoidal shape are supported by a mesh of strands (2/4) tensioned across the frame elements (figs. 2-4). The mirror is surrounded by an annular wing and covered by a transparent domed cover to reduce drag. <IMAGE>

Description

SOLAR POWERED VEHICLE This invention relates to a solar powered vehicle.

Solar powered aircraft have been developed in recent years as a result of pressure to promote environmentally friendly technology. To date these have largely been adaptations of conventional aircraft and as such they are limited to the use of solar cells for collecting the solar radiation and their available power is therefore limited by the efficiency of the cells and the area of the craft. These constraints place severe limitations on the prospects for solar powered aircraft for use as commercial passenger transporters.

According to the present invention there is a parabolic shaped mirror for directing electromagnetic radiation to its focus, where it can be collected. The energy of the electromagnetic radiation can then be converted, either directly or indirectly, to mechanical enery and this mechanical energy can be used to propel the craft. The electromagnetic radiation could be either direct sunlight, or a laser or maser beam produced from solar energy by a hig orbiting satellite.

The fundamental concept of the invention is the concentration of electromagnetic radiation at the focus of tfie mirror to be used as the prime source of energy for propelling an airborne vehicle.

A specific embodiment of the invention will now be described by wa?- of example with reference to the accompanying drancings. Figures 1 to 4 refer to the mechanical details of a mirror that would be used in a lightweight or demonstration model such as that illustrated in Figure 5.

Figures 6 to 8 illustrate possible commercial developments of the principle.

The parabolic mirror is segmented . It consists of a dishshaped "parabolic frame (1) which is used to support individual, trapezial 'mirror elements (2).

Figure 1 refers to the lightweight parabolic frame (1). This is fabricated from straight rods (1/1) of carbonfibre/resin, at least 2mm thick . The rods are cut to length then interconnected using suitably shaped plastic "frame connectors" (1/2) to form the frame illustrated.

Figures 2 and 3 refer to a typical mirror element. To form a mirror element, four rods of carbonfibre/resin (2/1) are interconnected using four plastic "element connectors" (2/2) to form a trapezial "element frame" as illustrated in figure 2. Each element frame is used to support a sheet of polyester sheet (2/3), which is trapezial and metallised on one side, as illustrated in figure 3. Each polyester sheet is at least 12 micrcns thick and is attached to its element frame using strands of catgut (2/4) which are tensioned across the element frame.

Figure 4 refers to a typical mirror element attached to the parabolic frame. Each mirror element is tied loosely to the parabolic frame, with its metallised surface to the inside of the dish, using very short loops of cat-gut (4/1). By suspending the mirror elements in this way, they will not bend even if the parabolic frame itself flexes, so that the metallised surface is kept sufficiently flat for its intended purpose.

Figure 5 shows a small demonstration model to be powered by solar energy. The solar energy is collected by an array of panels of solar cells which surround the focal point of the parabola and which is supported on a conical shaped tower as shown. The electrical power thus produced is conditioned by a conventional method then used to drive a lightweight electric motor which drives a propeller as shown. B drawing in air from above the craft and expelling it from its underside, the propellar causes the craft to be lifted.

Figure 6 shows a small manned model for use for leisure and sporting pursuits. The parabolic mirror and solar panels are designed using the same principle as the demonstration model, but the propeller is suspended beneath the craft so that it can be used to drive the craft horizontally. The orientation of the propellar is controlled manually in a vertical sense in order to raise or lower the craft, and in a horizontal sense in order to steer it to the left or right.

The parabolic mirror is surrounded by a flat. annular wing.

This enhances the streamlining and its upper surface is lined with further solar cells in order to collect additional solar energy, which is particularly useful when the sun is not directly overhead.

Optionally the parabolic mirror may have a transparent domeshaped cover. This should improve the aerodynamics and could be used to provide extra lift if the ovoid enclosed by it and the mirror contained warm air heated b the waste heat from the solar cells. However these advantages would have to be weighed against the possible disadvantages of both the absorption of incoming radiation by the cover, and the fact that the cover would add eight.

Figure 7 shows a large commercial model to be used for the transport of passengers and/or goods. It is not powered by direct solar radiation but by a maser whose power is derived from solar power by one of a system of high orbit satellites. It has a robust parabolic reflector with a metallic inner surface which will reflect microwaves efficiently. These microwave are collected b an array of receivers surrounding the focus of the mirror. The electrical energy thus produced is suitably conditioned so that it can be made to drive electric motors.

The craft has an annular wing whose upper surface ss lined with microwave receivers in order to supplement the power collected by the mirror. The electric motors are suspended breath the wing as shown. Each motor drives a propeller in order to drive the craft horizontally. The wing enhances the aerodynamics and streamlining of the craft,and helps with its stability.

There is a dome-shaped cover which is transparent to microwaves. The cover gives the craft an overall aerofoil shape so that it will rise when propelled horizontally. It also improves the streamlining, and protects the mirror surface. The volume enclosed by the mirror and the dome is partially filled with helium gas to supplement the lift.

The craft can be steered in the horiontal sense by varying the power to the port and starboard motors, so that a horizontal torque will be applied to the craft when these are unequal.

At the top of the craft there is a microwave transmitter.

This allows the satellite to locate the craft so that it can direct the maser to lock onto it.

Most of the ancillary equipment (erg. electrical power conditioners, passengers and/or goods) are located beneath the focus of the mirror as shown. At the bottom of the craft there is an undercarriage allowing it to take off and land horizontally.

Figure 8/1 illustrates the basic principle of a model in which the electromagnetic energy is converted to mechanical energy directly. The energy is absorbed at the focus of the parabolic mirror where it is converted to heat. On its wav to the focus, the electromagnetic radiation is passed through a membrane which will allow the electromagnetic radiation to pass through, but will not easily pass heat.

Hence the heat is trapped at the focus by a 'greenhouse effect'. The heat powers an engine which works by a turbo et te principle in which atmospheric air is drawn in from above the craft and expelled from its underside.

Figure 8/2 illustrates the basic principle of a model in which pulsed laser radiation of a suitable frequency, venerated on board a satellite, is directed towards small pellets of deuterium/tritium on board the craft. With present day inertial fusion technology the pellets could be made to implode resulting in an inertial fusion reaction in which neutrons are liberated. By absorbing the neutrons travelling in the upwards direction, and allowing those travelling in the downwards direction to escape, much of the momentum carried by the neutrons could be used to lift the craft.

Further schemes, not illustrated in the sketches, could include the following: 1. A mirror could be built using hexagonal/triangular rather than trapezial-shaped mirror elements.

2. A craft could be modified so that it can more easily collect radiation when its source is not directly overhead.

This could be achieved by having only a part-section of parabolic mirror, or by having manoeuverable mirror elements and/or solar panels. The movement and orientation of these would be computer-controlled.

3. Hybrid models could be made which could collect electromagnetic radiation of more than one frequency. An inner parabolic mirror would be used at higher altitudes to collect shorter wavelength radiation. This would be surrounded by a larger, annular mirror, with a parabolically curved surface, which would be used at lower altitudes to collect longer wavelength radiation, such as microwaves.

Generall, hybrid models could be of use in circumstances in which one or other of the frequencies is not always suitable for the climate or is enviromentally unacceptable.

Claims (7)

1. A solar powered vehicle which has a segmented( parabolic shaped mirror, to be directed towards a source of electromagnetic radiation, and which is composed of a parabolic shaped frame which supports individual, flat mirror elements. The electromagnetic energy is used to power the craft either directly, by using it to energise a propellant, or indirectly, by first converting it to electrical energy which is then used to drive a propeller.

2.A solar powered vehicle as in claim 1 wherein the craft is powered indirectly by a source of optical radiation (figure 5). The mirror comprises a parabolic frame which is used to support individual trapezial "mirror elements".The focal point of the mirror is surrounded by an array of panels of solar cells, which are supported on a central tower. The inside of the tower forms a funnel and the electrical power from the panels drives an electric motor mounted inside this. The motor in turn drives a vertici-axis propeller, which draws in air from above the craft, then expels it from its underside thereby giving it lift. At the top of the craft there is a beacon which is used to transmit a signal to inform the radiation source of the whereabouts of the craft.In order to overcome refraction effects, the wavelength of this signal is made equal to that of the incident radiation.

3. A solar powered vehicle as in claim 2 wherein the parabolic frame (figure 1 ) is fabricated from straight rods of carbonfibre/resin (1/1) interconnected by "frame connectors" (1/2). Each mirror element has a trapezial carbonfibre "element frame" (figure 2) which is formed br four rods of carbonfibre/resin (2/1) which are interconnected using four plastic "element connectors" (2/2). As illustrated in figure 3, a mirror element is formed by using an element frame to support a sheet of polyester sheet (2/3), which is trapezial and metallised on one side. The polyester sheet is attached to its element frame using strands of tensioned cat-gut (2/4). Each mirror element is attached to the parabolic frame using loops of cat-gut (4/1) in a manner illustrated in figure 4.

4. A solar powered vehicle essentially as in claim 2 but in which the electric motor and propeller are not mounted inside the central tower but instead are suspended beneath the parabolic mirror as illustrated in figure 6, ad which propel the craft horizontally. The orientation of the propeller can be altered, thus enablil the craft to be steered in both the horizontal and verticle senses. The parabolic mirror is surrounded by a flat, annular wing. the upper surface of which is lined witli additional solar c2 1 1 panels. A craft of thins nature would normally be powered b direct solar radiation.

5. A solar powered vehicle as in claim 1 wherein the craft is powered indirectly by a source of maser microwave radiation (figure 7). It has a robust parabolic reflector which has a metallic inner surface which will efficiently reflect microwaves. The focal point of the mirror is surrounded by microwave receiving waveguides, which are supported on a central tower. The parabolic mirror is surrounded by a flat, annular wing, the upper surface of which is lined with additional microwave receiving waveguides. The electrical power generated b the microwave receivers is used to power electric motors, suspended beneath the wing, each of which drives a propeller. There is a dome-shaped cover which is transparent to microwaves. The volume enclosed by the mirror and the cover is partially filled with helium gas.At the top of the craft there is a beacon, constituting a microwave transmitter, for informing the microwave source of the location of the craft. Most items of ancillary equipment are located beneath the focus of the mirror.

6. A solar powered vehicle as in claim 1 wherein the electromagnetic energy powers the craft direct (figure 8/1). There is a membrane surrounding the focal point of the mirror which will allow the electromagnetic radiation to efficiently pass through, but which will not easily pass heat, so that air on the inner side of the membrane can be heated. The membrane is supported on a central tower, and the inside of this forms a funnel. Inside this there is an engine, which uses the heat in a turbo-jet type principle drawing in air from above the craft and exhausting it down through the funnel to produce an upwards force on the craft.

As for claim 5, the craft also has an annular wing, a domeshaped cover and a beacon, and the void enclosed by the mirror and the cover is filled with helium.

7. A solar powered vehicle as in claim 1 wherein the craft uses a source of pulsed laser radiation (figure 8/2). It has a robust, segmented parabolic reflector which will efficiently reflect optical radiation. Surrounding the focal point of the mirror, and supported on a central tower, there is a spherical light guide which is used to direct the laser radiation towards a fuel of deuterium/tritium in the form of small pellets. The laser light causes the fuel pellets to implode resulting in the release of neutrons. Inside the top half of the light-guide, and concentric with it, there are successive, nested layers of neutron reflecting, moderating and absorbing materials, whose purpose is to absorb the momentum of upwards travelling neutrons. Neutrons travelling in the downwards direction are allowed to escape through the bottom of the craft. At the top of the craft there is a beacon. This craft does not depend on the atmosphere for its functioning, and could be flown in space . It could however be flown in the Earth's upper atmosphere , where it would require a transparent cover and an annular wing.