AID FOR TAKEOFF AND CLIMBING OF TRANSPORT AIRCRAFT BY TRACTION USING A CABLE

Abstract

The invention relates to the use of a device for assisting the take-off and climb of an airplane, the device comprising a traction cable, a first end of which is provided with fixing means for fixing it detachably to an airplane, and which can be driven by a drive device, for taking off and climbing a towed airplane, the towed airplane being a transport airplane and / or a cargo airplane, the fixing means being detached from the towed airplane when the towed airplane has reached an altitude greater than 1,000 m.

Description

Title of the invention: AID FOR TAKEOFF AND CLIMBING OF TRANSPORT AIRCRAFT BY TRACTION USING A CABLE

[0001] The present invention relates to the use of a device for assisting the take-off and climb of an airplane, the device comprising a traction cable, a first end of which is provided with fixing means for fixing it detachably to an airplane and which can be driven by a drive device. Technical field

[0002] All aircraft, at the time of takeoff and then during the climb, need a lot of power which they no longer need during horizontal flight. This enormous need for power generates two very different problems: - use of large, heavy, bulky and noisy power units (GMP) which increase the empty weight of aircraft and, above all, which drag and thereby reduce their glide ratio, leading to high fuel consumption during horizontal flight in cruise; very high noise nuisance and pollution during take-off and climb experienced by residents near airports. When the aircraft has reached a certain altitude, the rest of the flight can continue with much less power.

[0003] When the take-off runway is very short, as on an aircraft carrier, it is known to use a catapult equipped with a short sling which connects the towed aircraft to the launch shoe. The purpose of such a catapult is to give the aircraft sufficient speed for take-off. It is therefore not involved during the aircraft's ascent.

[0004] Document DE 25 53 064 A1 describes the use of an endless belt driven by a powerful electric motor and arranged under the take-off runway. A shoe connected to the endless belt projects above the runway and abuts against a corresponding member of the towed aircraft. At the end of its travel, the aircraft thus accelerated by the endless belt reaches a take-off speed that it could not have achieved with its own engines. Thus, the distance required for take-off is reduced, and the aircraft consumes less of its own energy. In this case too, the acceleration device only serves to accelerate the aircraft on the take-off runway. The device is decoupled from the aircraft at the latest at the time of take-off and is not used for climbing under any circumstances.

[0005] Document DE 299 01 958 U1 envisages the use of an aircraft tractor equipped with a winch. After the aircraft has been brought onto the runway by the aircraft tractor, the pull rod would be unhooked and replaced by the winch cable. The An aircraft tractor would go to the end of the runway by unwinding the cable and would install itself in an anchor. During acceleration, the winch would be activated and would assist the aircraft in its acceleration. The inventor indicates that the aircraft could thus be raised by a few meters. The invention would reduce the length of the takeoff runway as well as the energy consumption of the aircraft during takeoff. This device is therefore not used for climbing the aircraft.

[0006] Document EP 1 261 517 B1 describes a system for accelerating a load, in particular for launching an aircraft. The system comprises a pulley controlled by a power source, the pulley having a spirally profiled surface for receiving a cable, the remote end of which can be connected to the aircraft. The profiled surface ensures that the launching of the aircraft is carried out smoothly, first at a slow speed and then at a gradually increasing speed until the aircraft reaches take-off speed. This device is not used for the climb of the aircraft.

[0007] Concerning gliders, airplanes without engines, systems of driven cables are known. These cables are either connected to a winch placed on the takeoff runway, or pulled by a tow plane. They allow on the one hand to accelerate the glider to the takeoff speed and on the other hand to continue to pull it until it has reached a sufficient altitude to continue its flight thanks to the ascending air currents. When the glider has reached this altitude, which is generally about 500 m, the cable is released. The cable connected to an airplane is generally about 50 m, that connected to a winch is generally about 1,000 m.

[0008] The objective of the present invention intended for transport aircraft and / or cargo aircraft is multiple: - significantly reduce noise pollution and chemical pollution during take-off and climb; - reduce the empty weight of aircraft; - increase their finesse; - reduce the quantity of fuel on board; - significantly reduce fuel consumption both during takeoff and climb and during flight. Statement of the invention

[0009] This objective is achieved by the fact that the take-off and climb aid device is used to take off and climb a towed aircraft, the towed aircraft being a transport aircraft and / or a cargo aircraft, the means for attaching the traction cable being detached from the towed aircraft when the towed aircraft has reached an altitude greater than 1,000 m.

[0010] Depending on the needs, it is preferable to detach the fixing means from the towed aircraft when it has reached an altitude above 1,500 m, preferably above 2,000 m. Alternatively or additionally, the towed aircraft must reach its operational altitude before detaching the attachment means.

[0011] When the towed aircraft has reached the desired altitude, the towing cable is detached from the towed aircraft, which continues its flight under its own power. The takeoff and climb assistance device makes it possible to reduce the power of the towed aircraft's engines and thus reduce its fuel consumption during takeoff. It is therefore possible to provide aircraft with less powerful, lighter and less expensive engines. The aircraft's fuel reserves can also be reduced, which reduces the aircraft's takeoff weight.

[0012] In a first variant of the invention, the traction cable is driven by a traction winch located at the same level as the take-off runway, preferably on the take-off runway, in particular at or near the end of the take-off runway. It may also be located beyond the end of the runway, preferably substantially in the same plane as the take-off runway.

[0013] This traction winch pulls the towed aircraft by means of the traction cable firstly until it reaches its take-off speed, then until it reaches an altitude greater than 1,000 m, preferably greater than 1,500 m, and preferably greater than 2,000 m, and / or its operational altitude.

[0014] The length of a take-off runway for transport and cargo aircraft is generally greater than 3,000 m, and can reach 5,500 m. With a towing cable of 4,000 m length, it is possible to pull a towed aircraft to an altitude of 2,000 m.

[0015] When the desired altitude is reached, the tow cable is detached from the towed aircraft in the same way as for gliders. The part of the cable that is not wound, which constitutes the tow cable itself, and the fixing means fall to the ground. The tow cable can either be wound onto the tow winch for storage, or unwound from the tow winch to bring the fixing means to a new starting point for the next takeoff. A small parachute can be provided to prevent the tow cable and fixing means from falling too sharply.

[0016] This traction winch is preferably an electric traction winch.

[0017] Electric winches are significantly less noisy than motor winches. thermal. The noise pollution during takeoff is thus significantly reduced.

[0018] In order to avoid having to unwind the traction cable before each take-off in order to return the fixing means to the starting point, it is possible to provide a recall winch, also known as a redrive winch. This recall winch is placed on the runway opposite the traction winch. A recoil cable, the free end of which is attached to the traction cable attachment means, is wound onto the recoil winch. The recoil winch is designed to allow the recoil cable to unwind during takeoff and ascent of the towed aircraft, and to recoil the recoil cable after detachment of the attachment means in order to, on the one hand, return the attachment means to a new starting point, and on the other hand, uncoil the traction cable. Thus, during takeoff, the recoil cable uncoils, driven by the towed aircraft rolling on the runway and then taking off. When the towed aircraft has reached the desired altitude, the attachment means are detached and the traction winch is stopped while the recoil winch is started. The recoil cable is wound onto the recoil winch, returning the attachment means to the starting point on the runway and uncoiling the traction cable at the same time.

[0019] A second variant of the invention consists of using a traction cable driven by a towing aircraft.

[0020] The tow aircraft pulls the towed aircraft until it reaches its take-off speed, then continues to pull it until it has reached an altitude greater than 1,000 m, preferably greater than 1,500 m, and preferably greater than 2,000 m, and / or its operational altitude. Then, the tow cable is detached from the towed aircraft in the same manner as for gliders. This procedure is the same as that commonly practiced for gliders, but the towing of the towed aircraft continues at much higher altitudes.

[0021] The tow aircraft is preferably a turboprop aircraft.

[0022] Turboprop aircraft, particularly large propeller turboprop aircraft, perform well at these relatively low speeds.

[0023] Since the tow plane that drives the traction cable does not travel long distances, it is also possible to use an electric motor plane, which reduces noise pollution during takeoff.

[0024] It is preferable in the context of the present invention to use a lightweight traction cable, in particular a carbon fiber cable. The recall cable, for its part, does not need to be particularly strong, since it does not contribute to the traction of the towed aircraft.

[0025] The invention also relates to a method for assisting takeoff and climb for an airplane of the transport airplane and / or cargo airplane type. The airplane is towed by means of a takeoff and climb assistance device comprising a traction cable, a first end of which is provided with fixing means for fixing it detachably to the towed airplane and which can be driven by a drive device. In the method of the invention, - the fixing means are fixed to the towed aircraft, - the towed aircraft is then towed by the drive device to an altitude greater than 1,000 m, preferably greater than 1,500 m, and preferably greater than 2,000 m, and / or to its operational altitude, - then the fixing means are detached from the towed aircraft. During takeoff and climb, the towed aircraft has its own engines switched off, or at most at idle. This makes it possible to considerably reduce noise and chemical pollution at the takeoff runway, and to reduce fuel requirements. The engines of the towed aircraft are preferably only switched to the power required for continued flight, generally full power, shortly before the tow cable is detached. Examples of achievements

[0026] An exemplary embodiment of the invention is explained below.

[0027] The main idea of ​​the invention is to transpose to commercial aviation what has been done for decades in light aviation, namely to assist the take-off and climb of gliders.

[0028] However, the turbojets installed on transport aircraft have low take-off and climb efficiencies, because they have a small air passage section, even if they are double-flow, the flight speed being low (see Froude theory).

[0029] A first possibility to improve this situation is to help the aircraft to gain speed, take off and then climb using a traction winch. With a powerful winch, it is possible, on current airfields, to climb to almost 2,000 m depending on the length of runway available. This traction winch can be electric, which considerably reduces noise and pollutant emissions.

[0030] Another solution, also used successfully for decades in light aviation, is to use a tow aircraft specially adapted to the climb speed of the aircraft. This tow aircraft will be equipped with one or two turboprop engines with large propellers, rotating slowly and therefore having good efficiency at these relatively low speeds. It is also possible to consider the use of electric motors with energy recovery during descent and reduced noise emissions.

[0031] Therefore, a towed aircraft is connected to a traction cable driven by a drive device. In the first embodiment, the drive device for the traction cable essentially consists of a traction winch arranged on the takeoff runway, preferably at the end of the runway or close to the end of the runway. In the second embodiment, the drive device is a tow aircraft. In both cases, it is preferable for the motor of the winch or that of the tow aircraft to be an electric motor in order to reduce noise pollution during takeoff and the climb phase of the towed aircraft.

[0032] In the case of winch traction, the cable has a part which remains unwound as long as the cable is attached to the towed aircraft: this part of the cable strictly speaking constitutes the traction cable within the meaning of the invention. The remainder of the cable, which is partly unwound at the start of the maneuver, forms part of the drive means with the traction winch. The part of the cable which remains unwound as long as the cable is attached to the towed aircraft is therefore driven by the other part which is wound onto the traction winch. In the case of traction by towing aircraft, the traction cable is driven by the towing aircraft.

[0033] The first end of the traction cable is detachably attached to the towed aircraft using attachment means. Once the desired altitude has been reached, greater than 1,000 m, preferably greater than 1,500 m, and preferably greater than 2,000 m, and / or the operational altitude, the traction cable is detached from the towed aircraft and falls back to the ground.

[0034] In order to reduce the weight of the traction cable, it is preferably made of a light but strong material such as carbon fibers.

[0035] Furthermore, the transport aircraft must always be able to fly and even be able to climb slightly if an engine fails (Nl) as required by the standards (JAR; FAR; ETOPS, etc.). The power of the engines must therefore be chosen according to the minima imposed by the aforementioned standards. One solution to best regulate the flight with (Nl) is to use three small reactors, instead of two.

[0036] The invention has the following advantages: - by using an electric traction winch or an electric towing aircraft, it is possible to considerably reduce noise pollution and pollutant emissions during take-off and climb; the energy required for acceleration and the first phase of climb being provided largely by the drive system, it is possible to equip transport or cargo aircraft with less powerful engines, therefore lighter and less bulky. The empty weight of the towed aircraft is therefore lower and its glide ratio higher, which again allows for a reduction in fuel consumption. The use of lighter and especially less bulky turbojets allows for a significant gain in glide ratio. Current airliners have a maximum glide ratio of around 17 whereas an aircraft without today's large jet engines can exceed 22 as demonstrated by the "Caravelle" SE 210 50 years ago! The reduction in the mass of the jet engines, combined with the aerodynamic improvement, allows for a reduction of more than 35% in kerosene consumption in horizontal flight cruising; - when the training device is a tow plane, it can be single-seater or two-seater, and it can be equipped with one or two turboprop engines with large propellers, rotating slowly and therefore having good efficiency at these relatively low speeds; - the use of a take-off and climb assistance device according to the invention is complementary to current research aimed at lightening transport aircraft by replacing kerosene with hydrogen, by using hybrid systems combining thermal generators and electric motors, or even using entirely electric motors. In other words, the invention can be applied to electric towed aircraft.

Claims

Claims

1. Use - of a device for assisting the take-off and climb of an airplane, the device comprising a traction cable, a first end of which is provided with fixing means for fixing it detachably to an airplane, and which can be driven by a drive device, - for taking off and climbing a towed airplane, the towed airplane being a transport airplane or a cargo airplane, the fixing means being detached from the towed airplane when the towed airplane has reached an altitude greater than 1,000 m, the traction cable being driven by a traction winch located at the same level as the take-off runway.

2. Use according to claim 1, characterized in that the fixing means are detached from the towed aircraft when the towed aircraft has reached an altitude greater than 1,500 m, preferably greater than 2,000 m.

3. Use according to claim 1 or 2, characterized in that the traction cable is driven by a traction winch located on the take-off runway, preferably at or near the end of the take-off runway.

4. Use according to one of the preceding claims, characterized in that the traction winch is an electric traction winch.

5. Use according to one of the preceding claims, characterized in that a recall winch is placed on the runway opposite the traction winch, and on which is wound a recall cable whose free end is fixed to the fixing means, the recall winch being designed to let the recall cable unwind during takeoff and ascent of the towed aircraft, and to wind the recall cable after detachment of the fixing means in order to return the fixing means to a new starting point and unwind the traction cable.

6. Use according to one of the preceding claims, characterized in that the traction cable is a carbon fiber cable.

7. Method for taking off a towed aircraft, the towed aircraft being a transport aircraft or a cargo aircraft, by means of a take-off and climb assistance device comprising a traction cable, a first end of which is provided with fixing means for fixing it detachably to the towed aircraft and which can be driven by a traction winch located at the same level as the take-off runway, method in in which the attachment means are attached to the towed aircraft, the towed aircraft is towed by the drive device to an altitude above 1,000 m, and then the attachment means are detached from the towed aircraft.

8. Method according to the preceding claim, characterized in that the engines of the towed aircraft are switched off or idle during takeoff and climb.

9. Method according to the preceding claim, characterized in that the engines of the towed aircraft are set to a power necessary for the continuation of the flight after a first climb phase and before the detachment of the fixing means.