RU2851889C1 - Modular twin-engine heavy transport unmanned platform of aircraft type - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to the field of aviation, in particular to designs of transport unmanned platforms of aircraft type. The modular twin-engine heavy transport unmanned platform of aircraft type includes a fuselage made twin-beam, with removable wing consoles and a power plant. The power plant contains two internal combustion engines installed in separate removable symmetrical side compartments of the fuselage, including the engine, fuel tank and engine control electronics. Each engine rotates an air propeller, wherein the air propellers rotate in opposite directions "inward" to compensate for asymmetric aerodynamic effects. The platform is equipped with an engine speed synchronisation system and onboard radio-electronic equipment. A mounting system for quick-release payload modules installed under the central part of the fuselage is provided.

EFFECT: increase in flight safety, operational efficiency, maintainability, versatility of application.

8 cl, 5 dwg

Description

Field of technology to which the invention relates

The invention pertains to unmanned aviation, specifically to heavy-duty, modular, aircraft-type unmanned aerial vehicles (UAVs) designed to transport various payloads weighing up to 100 kg over long distances (up to 1,500 km) and perform a wide range of tasks by installing interchangeable payload modules. The platform can be used for logistics operations, monitoring, aerial photography, radio reconnaissance, and other applications requiring high payload capacity, long range, and the ability to operate in a variety of conditions, including unprepared sites.

State of the art

The prior art includes various designs of unmanned aerial vehicles intended for transporting cargo and performing multi-purpose tasks.

Known patent RU 2833448 C1 "Unmanned aerial vehicle for cargo transportation" contains a fuselage consisting of a nose section, a section of constant cross-section and a tail section with horizontal and vertical tail surfaces, a cargo compartment equipped with a ramp and two side flaps, a tricycle chassis, a bearing surface, a power plant on the consoles of the bearing surface, an automatic control system for on-board equipment, wherein the bearing surface is mechanized by slotted flaps in the tail section, the cargo compartment is equipped with guides for placing a cargo module and locks for fixing it.

The disadvantages of the analogue are:

• Limited load capacity: the design is aimed at transporting loads of lesser weight than in the claimed invention.

• Range and Versatility: Specialized stealth features (e.g., canopy, lift-off balloon) can add weight and complexity, potentially reducing range and versatility for heavy-lift missions.

• Power plant and redundancy: the analogue is not oriented towards redundancy, which reduces the level of safety when performing long transport flights.

• Focus on low visibility: While radar-lowering and stealth features (radio-absorbing materials, canopy, RFID tag) are an advantage in the analogue for special missions, they are not a priority for cargo transport operations where payload and range are more important.

Known patent RU 195392 U1 "Unmanned aerial vehicle", made according to the aerodynamic aircraft configuration of a monoplane, containing a fuselage connected to the tail unit by means of a carbon fiber tube secured along the longitudinal axis of the aircraft, removable wings connected to the fuselage by means of carbon fiber tubes passing through the fuselage and secured with the help of threaded and locking connections, two electric motors with electric batteries connected to tractor propellers installed symmetrically on the wings, wherein the fuselage, wings and tail unit of the UAV are made of foam plastic, the fuselage is made hollow and equipped with a rigid wooden support located in the lower part of the fuselage, carrying equipment and performing the function of a landing surface, and an autopilot is installed to control the UAV.

The disadvantages of the analogue are:

• Limited payload and range: The counterpart is focused on light weight and specialized surveying, resulting in lower payload and consequently more limited range.

• Single-engine (or less redundant) propulsion system: using one or more small electric motors in an analogue does not provide a sufficient level of reliability and redundancy, which is critical for transport and cargo missions.

• Limited payload modularity: the analogue is focused primarily on filming tasks with fixed payload options (Sony A6000, Micasence RedEdge cameras, etc.), which does not provide flexibility for quickly switching between transport, cargo and specialized UAV tasks.

• Design compromises for lightness: the use of foam and lightweight materials in the analogue allows for a reduction in weight, but can limit the strength of the structure, especially when operating in difficult conditions (unprepared strips, landing on water/snow), which is critical for a transport platform.

Russian patent RU2776617C1, "Transport Cargo Unmanned Aerial Vehicle," published on July 22, 2022, was selected as the closest analogue ( prototype ) for the claimed invention. This UAV comprises a fuselage consisting of a nose section, a constant cross-section section, and a tail section with horizontal and vertical stabilizers. A cargo compartment equipped with a ramp and two side doors, a tricycle landing gear, a lifting surface, a power plant mounted on the lifting surface consoles, and an automatic onboard equipment control system. The cargo compartment is equipped with guides for accommodating the cargo module and locks for securing it.

The disadvantages of the prototype are:

• Lack of power plant redundancy, which reduces reliability when performing long missions in difficult conditions.

• The occurrence of uncompensated asymmetric aerodynamic effects from the operation of the propellers of the power plant (such as a shift in the thrust vector due to the angle of attack of the blades, asymmetrical blowing on the wing and fuselage), which leads to the appearance of undesirable rolling and yaw moments, complicates control, increases the load on the control surfaces and the automatic control system, and also leads to the presence of a “critical engine”, the failure of which significantly complicates flight stabilization.

• Limited versatility of application and difficulty of adaptation to different types of payloads and operational requirements due to the non-modular design of the main units (power plant, wings).

• Complexity of maintenance and repair of the power plant in the field.

• Low level of reliability when transporting heavy loads (up to 100 kg) over long distances (up to 1500 km).

The following essential features have been identified for the claimed invention in common with the prototype: a modular, twin-engine, heavy-duty, unmanned transport platform of the aircraft type, including a fuselage, wings, a power plant with two internal combustion engines and propellers, on-board electronic equipment, and a fastening system for payload modules.

The essence of the invention

The technical problem that the claimed invention is aimed at solving is the creation of a modular, twin-engine, heavy-duty, unmanned transport platform of an aircraft type with increased flight safety, improved flight performance characteristics, a simplified control system, high operational efficiency, and versatility.

The achieved technical result consists in increasing the flight safety and operational efficiency of the twin-engine unmanned platform.

This is achieved through:

• Improving its flight performance characteristics, namely: compensating for asymmetric aerodynamic effects (associated with the P-effect, asymmetric blowing of the wing and fuselage) that arise during the operation of the propellers, which leads to increased directional stability and controllability, a reduction in unwanted rolling and yaw moments, and, as a consequence, a reduction in the load on the control surfaces;

• Elimination of the concept of a “critical engine”, which improves safety in the event of failure of one of the engines and simplifies the logic of the automatic control system for such scenarios;

• Ensuring high maintainability and efficiency of maintenance due to the modularity of power plants (propeller-motor groups);

• Ensuring versatility and adaptability of the platform to various tasks and operating conditions due to the modularity of the payload and the possibility of wing modification. These aspects together contribute to achieving such characteristics as high payload capacity (up to 100 kg), long flight range (up to 1,500 km), and the ability to operate in various conditions, including takeoff and landing on unprepared sites.

The said technical result is achieved by the fact that in a twin-engine heavy unmanned transport platform of an aircraft type, including a fuselage, wings, a power plant with two internal combustion engines and propellers, as well as on-board radio-electronic equipment, according to the invention, the fuselage is made of a twin-boom; two internal combustion engines of the power plant are installed in separate symmetrical compartments located on the wings, wherein each engine rotates its own propeller, and the propellers rotate in opposite directions to compensate for the total reactive torque; wherein the compartments for the engines are made with aerodynamic fairings that reduce drag; the platform is equipped with a system for synchronizing the speed of the said two engines; the on-board radio-electronic equipment includes, at least, an autopilot with satellite navigation and a communication system that ensures control of the platform via a radio channel; in addition, the platform is equipped with a fastening system for quickly removable payload modules that ensures their prompt connection to the on-board electrical network of the platform.

List of figures (drawings):

Fig. 1 - General view (axonometric view) of a modular twin-engine heavy transport unmanned aircraft-type platform, showing a twin-boom fuselage, wings, symmetrical arrangement of engine compartments, propellers, and a place for installing a payload module.

Positions: 1 - fuselage (twin-boom), 2 - wing, 3, 3' - engines (inside compartments), 4, 4' - engine compartments, 5, 5' - propellers, 6, 6' - aerodynamic fairings, 7 - payload module fastening system, 8 - payload module (contour).

Fig. 2 - Diagram of the arrangement of the propeller-motor modules of the internal combustion engine, illustrating the aerodynamic fairing 6 (side view).

Positions: 2 - wing (part), 3 - engine, 4 - compartment, 6 - aerodynamic fairing.

Fig. 3 - Diagram of counter-rotating propellers "inward".

Positions: 5, 5' - propellers.

Fig. 4 - Example of a quick-release payload module and its attachment system to the fuselage.

Positions: 1 - fuselage (part), 7 - fastening system, 8 - payload module.

Fig. 5 - Side view of the platform showing the wing profile, fuselage, power plant location and payload module.

The claimed platform (Fig. 1) includes a twin-boom fuselage 1. Wings 2 (left and right) are attached to fuselage 1. The wings are removable due to a wing spar inserted into the fuselage and connected by threaded and locking connections.

The platform includes a twin-boom fuselage 1. Fuselage 1 is structurally composed of a central section (not shown separately) and two removable symmetrical lateral compartments 4 and 4'. Wing consoles 2 are also removable and are attached to fuselage 1 (e.g., to the central section or to transition elements connected to the lateral compartments), which simplifies platform transportation and allows for modification of the wing structure to alter flight performance characteristics (payload weight, rate of climb, maneuverability, etc.) without altering the remaining platform elements.

The platform's power plant consists of two internal combustion engines (ICE) 3 and 3' (e.g., with a volume of 183-294 cm³ each, manufactured by DELMOT LLC, Krasnoyarsk), each housed in its own removable side fuselage compartment 4 and 4', respectively. Each side compartment 4, 4' is a propeller-motor module of the ICE, which includes, in addition to the ICE 3 (3') itself, a fuel tank (not shown) and engine control electronics (not shown). In addition, engines 3 and 3' can be installed in compartments 4 and 4' using shock absorbers (not shown) to reduce vibrations and quick-release fasteners (not shown) to facilitate maintenance and replacement of the ICE. The engine module, designed as a 4- or 4-inch compartment with a 3- or 3-inch engine installed, can have an identifier for transmitting maintenance information and can be equipped with a sensor system for monitoring the engine's condition. This modularity of the power plants allows for the rapid removal of the entire propeller-motor module for maintenance or replacement without the need to transport the entire platform to a repair shop.

Compartments 4, 4' are made with aerodynamic fairings 6 (Fig. 2), which reduce the aerodynamic drag of the side compartments, improving the overall aerodynamic characteristics of the platform, for example, increasing the rate of climb, and can provide protection for the engines from external influences, and reduce the load on the controls.

Each engine 3, 3' drives propeller 5, 5', respectively. A key feature is that propellers 5 and 5' rotate in opposite directions, "inward," meaning the upper blades of the propellers move toward the fuselage (Fig. 3). This direction of rotation compensates for a number of asymmetric aerodynamic effects inherent in twin-engine configurations with identical propeller rotation directions:

• P-effect compensation (thrust vector shift): at an angle of attack, a downward-moving propeller blade produces more thrust than an upward-moving blade. With the propellers rotating at the same speed, this causes the thrust vector of each propeller to shift in the direction of rotation, and if the engine axes are parallel, one engine's thrust lever relative to the UAV's longitudinal axis of symmetry is greater than the other, causing an undesirable yawing moment. With the propellers rotating inward in the opposite direction, these thrust vector shifts become symmetrical and either compensate for each other or create a symmetrical flow pattern that does not result in a significant uncompensated yawing moment.

• Compensation for asymmetrical wing flow: High thrust on one side of the propeller leads to increased airflow speed and, consequently, lift on that section of the wing. With equal rotation, this causes an asymmetrical increase in lift on the wing panels, resulting in a rolling moment. Opposite inward rotation of the propellers creates a symmetrical flow pattern on the wings, eliminating or significantly reducing this unwanted rolling moment.

• Symmetrization of swirling flow: propellers create a swirling airflow (slipstream), which, when interacting with the fuselage and empennage, can cause additional pitching and yaw moments. Opposite inward rotation of the propellers creates two symmetrically swirling flows, the interaction of which with the UAV airframe becomes more symmetrical, reducing unwanted moments.

This propeller rotation scheme eliminates the concept of a "critical engine"—that is, the engine whose failure has the most adverse impact on controllability. If any engine fails, the resulting asymmetric torques and the UAV's behavior become identical (mirrored), significantly simplifying the automatic control system (autopilot) logic when dealing with such failures and improving overall flight safety. Furthermore, when the propellers rotate inward, the effective distance between the thrust vectors can be smaller than the distance between the propeller axes, which contributes to increased lateral stability.

The platform is equipped with a system for synchronizing the speeds of internal combustion engines 3 and 3' (not shown), including gyroscopes and tachometers. This system maintains a constant or specified small difference in engine speed (e.g., Δn ≤ 200 rpm), minimizing vibration and ensuring uniform total thrust, contributing to flight stability. This is important for stable flight and preventing yaw moments during uneven engine operation, improving directional stability and control.

The on-board radio-electronic equipment (avionics) of the platform (not shown) includes, at a minimum, an autopilot with satellite navigation to ensure automatic or semi-automatic flight along a given route, a surveillance video camera to monitor the situation and/or perform target tasks, a communications system that ensures control of the platform via a radio channel from a ground control station, as well as other necessary sensors and systems to ensure flight and perform target tasks.

The platform is equipped with a fastening system 7 (Fig. 1, Fig. 4) for quickly removable payload modules 8, located under the central section of the fuselage 1. This external location of the payload module has a number of advantages:

• In the case of using a jettisonable module, after its separation, the frontal profile of the platform and its aerodynamic drag are significantly reduced, which leads to an increase in flight range.

• When using small payload modules (for example, for geodesy), the overall aerodynamic drag of the platform will also be lower compared to the option of placing the payload inside a voluminous fuselage, which has a positive effect on flight range.

• The external location of the module provides significant scope for various design versions of payload units without strict restrictions on the internal dimensions of the compartment.

• There is no need for cargo compartment doors, which reduces the number of mechanical components, reduces weight, and increases reliability. The fastening system ensures mechanical fixation of Module 8 and its quick connection to the platform's on-board electrical system, for example, via a "blind docking" electrical connector.

Attachment system 7 mechanically secures module 8 to fuselage 1 (or a dedicated compartment) and quickly connects it to the platform's onboard electrical system, for example, via a blind-docking electrical connector. This allows for quick payload changes depending on the mission. Payload modules 8, for example, can be designed as follows:

• quick-release cargo container;

• module for monitoring and drawing up orthophoto plans;

• module for a jettisonable gliding container;

• module for a droppable cargo container on a ballistic parachute;

• module for radio reconnaissance and retransmission.

The platform is designed for a takeoff weight of up to 350 kg and a payload capacity of up to 100 kg over a range of up to 1,500 km. The platform's design and control system enable takeoff and landing on unprepared runways, as well as on water and snow, significantly expanding its range of applications. This requirement is met by various chassis designs, tailored to the customer's needs during the platform assembly stage.

The platform is manufactured using readily available domestic materials and technologies, such as laser cutting and vacuum forming, with a planned localization rate of up to 100%.

An example of the implementation and operation of a modular twin-engine heavy unmanned transport platform of the aircraft type

The operation of the invention is carried out as follows and illustrates the implementation of the stated technical advantages using the example of a specific implementation of a platform with specified characteristics.

Before operation, one of the quickly removable payload modules 8 (Fig. 4) is installed on the platform; for example, a cargo container capable of holding up to 100 kg of cargo. Module 8 is secured by fastening system 7 and connected to the platform's on-board electrical system, which supplies power to its systems. Pre-launch preparations are performed, including testing of all platform systems, including internal combustion engines (ICE) 3 and 3' (e.g., two-stroke or four-stroke ICEs with a capacity of 183-294 cm³ each) and their control systems. Wing consoles 2 and removable side compartments 4, 4' (propeller-motor modules) are pre-assembled and tested.

When internal combustion engines 3 and 3' are started and operating, propellers 5 and 5' begin to rotate in opposite directions "inward" (the upper blades move toward the fuselage, Fig. 3). This design solution specifically neutralizes a complex of asymmetric aerodynamic effects:

• P-effect (P-factor): asymmetry or difference in thrust between the descending and ascending blades of a propeller in the presence of an angle of attack, which, with the same rotation of the propellers on a twin-engine aircraft, leads to asymmetry of the thrust levers relative to the center of mass and, as a consequence, to an undesirable yawing moment, is compensated for by the symmetrical arrangement and opposite direction of rotation of the propellers.

• Asymmetrical wing flow: the increase in lift in the section of the wing behind the propeller, which, with the same propeller rotation, is also asymmetrical and causes a heeling moment, is symmetrized, eliminating or significantly reducing this unwanted roll.

• Slipstream: two symmetrically swirling flows from the inward rotating propellers interact more favourably with the twin-boom fuselage 1 and the empennage, minimizing the roll and yaw moments they cause.

The 3 and 3' engine speed synchronization system, receiving data from the tachometers and gyroscopes included in the avionics, maintains coordinated engine operation with minimal differences in speed (e.g., Δn no more than 200 rpm), ensuring uniform thrust and preventing additional yaw moments. This is especially important during maneuvering and in turbulent conditions.

This powertrain design eliminates the concept of a "critical engine." In the event of failure of either engine 3 or 3', the platform's behavior and the resulting compensating torques become symmetrical and predictable, significantly simplifying the autopilot's failure-management algorithms and improving overall flight safety. The platform's directional stability and controllability are enhanced, and the load on the control surfaces is reduced.

Flight is controlled by an autopilot along a pre-programmed route or by an operator directly from a ground control station via a secure radio channel. Onboard avionics, including an inertial navigation system, satellite navigation (GLONASS/GPS), an altimeter, and other sensors, ensure precise route following and flight mission execution. Aerodynamic fairings for the six propeller-motor modules (4, 4') (made of composite materials, such as carbon fiber, with a low drag coefficient of no more than 0.01, profiled to minimize drag, such as a NACA 2315 profile) reduce the platform's overall aerodynamic drag, contributing to fuel savings and a flight range of up to 1,500 km.

The twin-boom design of fuselage 1 provides the necessary strength and rigidity to support the loads from the wings, power plant, and payload, and also provides a convenient and aerodynamically advantageous placement for payload module 8 under the central section. The external location of payload module 8 has the following advantages:

• When using a jettisonable PN module, after its separation the aerodynamic drag of the platform is reduced, which has a positive effect on the remaining flight range.

• When installing a compact payload module (for example, for aerial photography), the drag is less than that of platforms with an internal compartment of similar capacity, which also increases the range.

• Provides flexibility in the design and dimensions of the PN modules.

• Eliminates the need for cargo compartment door mechanisms, reducing weight and increasing reliability.

The platform is capable of taking off and landing on unprepared dirt runways, and also, when equipped with appropriate landing gear (e.g. float or ski, not shown), on water or snow surfaces.

The modularity of the platform design is evident not only in the interchangeable payload, but also in the design of the propeller-motor groups and wings themselves:

• Removable side compartments (propeller-motor modules) 4, 4': each such module, including the internal combustion engine 3 (3'), fuel tank, engine control system components and fairing 6, can be quickly dismantled and replaced as a whole for maintenance or repair in specialized conditions, without the need to transport the entire platform to a repair shop. This significantly increases maintainability and reduces platform downtime.

• Removable wing consoles 2: simplify the platform's transportation to the operational site. Furthermore, this design solution allows for future modifications to the wing structure (e.g., changing its geometry, profile, and mechanization) to adapt the platform to specific requirements (changes in payload weight, rate of climb, maneuverability, takeoff/landing length) without significant alterations to the remaining structural elements, ensuring the platform's high adaptability.

Upon completion of the flight mission or if refueling or servicing is required, the platform lands. Eight payload modules can be quickly swapped out, allowing the platform to be quickly reconfigured for the next mission.

Thus, the proposed design and operating principles of the invention ensure the achievement of the stated technical result, expressed in increased flight safety and operational efficiency of a twin-engine unmanned platform.

Claims (8)

1. A modular twin-engine heavy transport unmanned aircraft platform comprising a fuselage (1), wings (2), a power plant with two internal combustion engines (3, 3') and propellers (5, 5'), on-board radio-electronic equipment and a fastening system (7) for payload modules (8), characterized in that the fuselage (1) is made of two booms and consists of at least a central section and two removable side compartments (4, 4'); the wing consoles (2) are made removable and are fastened to the fuselage (1); two internal combustion engines (3, 3') of the power plant are each located in its own removable side compartment (4, 4') of the fuselage, wherein each side compartment (4, 4') is a propeller-motor module including an internal combustion engine (3, 3'), a fuel tank, engine control electronics elements and an aerodynamic fairing (6); wherein each engine (3, 3') rotates its propeller (5, 5'), and the propellers (5, 5') are configured to rotate in opposite directions "inward"; the platform is equipped with a system for synchronizing the speed of the two engines (3, 3'); the onboard radio-electronic equipment includes at least an autopilot with satellite navigation and a communication system, and the fastening system (7) for the quickly removable payload modules (8) is located under the central section of the fuselage (1) and ensures the possibility of their prompt connection to the onboard electrical network of the platform. 2. The platform according to item 1, characterized in that the engines (3, 3') are installed in the compartments (4, 4') by means of quick-release fastening units. 3. The platform according to item 1, characterized in that the engines (3, 3') are installed in the compartments (4, 4') using shock absorbers. 4. The platform according to claim 1, characterized in that the fastening system (7) for the quickly removable payload modules (8) is made with a “blind docking” type electrical connector. 5. The platform according to paragraph 1, characterized in that it is designed with the possibility of takeoff and landing on unprepared runways. 6. The platform according to item 1, characterized in that it is designed with the possibility of landing on a water surface and/or snow. 7. The platform according to item 1, characterized in that the speed synchronization system is equipped with gyroscopes and tachometers, and ensures speed synchronization Δn of no more than 200 rpm. 8. The platform according to item 1, characterized in that the fairings of the side compartments are made of carbon fiber with a NACA 2315 profile and have a drag coefficient of no more than 0.01.