Aircraft with three lifting surfaces offering high stability and agility
The aircraft design with three lifting surfaces addresses control challenges by optimizing airflow and lift distribution, achieving high stability and agility through specific configurations and control systems, enhancing stall margin and reducing drag.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- CHUDZIK CLAUDE
- Filing Date
- 2022-12-14
- Publication Date
- 2026-06-26
AI Technical Summary
Existing aircraft designs with three lifting surfaces face challenges in controlling interactions between the surfaces, leading to instability and difficulty in achieving high stability and agility.
An aircraft design with three active lifting surfaces, including a canard wing, main wing, and horizontal tail assembly, featuring specific aerodynamic configurations and control systems to manage airflow and lift distribution, combined with a propulsion system at the rear of the fuselage, and a composite material construction.
The design achieves high stability and agility, with improved stall margin, reduced drag, and enhanced control in turbulent conditions, enabling efficient takeoff and maneuverability.
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Abstract
Description
Title of the invention: Aircraft with three lifting surfaces offering high stability and high agility.
[0001] The field of the invention relates to a light aircraft comprising three lifting surfaces and a propulsion system located at the rear of the fuselage. State of the art
[0002] On aircraft, the aerodynamic benefit of three lifting surfaces has been recognized for many years; however, few concrete designs have been put into flight due to the difficulty in controlling the interactions between the different lifting surfaces. The best-known aircraft with three lifting surfaces is the Piaggio Avanti P 180, which is the subject of patent EP 0 084 686 B2. Other manufacturers (Airbus) are interested in such architectures, as indicated in patent FR 1257269. Burt Rutan's Catbird experimental aircraft is also a good example of an aircraft with three lifting surfaces. Technical characteristics of the invention
[0003] This invention relates to an aircraft comprising three active lifting surfaces fixed on a fuselage (Figures 1, 2, 3). The load-bearing surfaces are arranged as follows: - A lifting surface placed at the front of the fuselage in the upper part (canard wing). - A main lifting surface located between the first quarter and last quarter of the fuselage (main wing). - A lifting surface located at the rear end of the fuselage in the upper part, at the top of the fin (horizontal tail assembly). The leading edge, commonly called a canard, is positioned at the top of the fuselage. This position allows the airflow to be channeled upstream of the main wing. At high angles of attack, the presence of this leading edge reduces the angle of attack on the main wing and increases the stall margin. In fact, the canard is the first wing to stall, resulting in a smooth and easily controllable stall. The swept main wing with negative dihedral is positioned low on the fuselage. It is wedged and twisted to ensure even pressure distribution across its entire surface. Its shape and position are designed to take advantage of the upstream flow deflection by the canard. The sweep helps maintain low drag at high speeds. On the leading edge of each main wing, a stalling generates a disturbed flow at large angles in order to prevent a partial and local stall. The horizontal tail assembly is positioned at the top of the vertical tail assembly, its profile is reversed. During cruising, the aerodynamic forces are distributed as follows ([Fig.4]): Fl= 0.1 g, F2=0.75 g, F3=0.15 g, all surfaces are lifting. The horizontal stabilizer is positioned at the top of the vertical stabilizer so that the airflow upstream of this surface is not disturbed by wakes from the canards and main wings. The horizontal stabilizer has an inverted airfoil that is asymmetrical with respect to the canards and the main wing. During takeoff or when entering a pitch-up, the aerodynamic forces on the rear surface are reversed. This improves the aircraft's rotation and reduces the takeoff distance. During takeoff, the aerodynamic forces are distributed as follows: Fl=0.15 g, F2=0.95 g, F3=-0.1g ([Fig. 5]). This lift reversal during pitch-up allows for a high rate of turn and makes the aircraft very agile. Two streamlined stabilizing fins with reverse dihedral are positioned at the rear of the fuselage. These two fins are positioned at 30° on either side of the fuselage.These two surfaces are designed to prevent excessive pitching of the aircraft; they contribute to the aircraft's stability in the presence of strong turbulence. These two profiled surfaces are essential for ensuring the aircraft's excellent stability. When the angle of attack is positive, these surfaces generate lift; when the angle of attack is negative, the lift reverses and becomes negative. The canard and main wing, positioned on either side of the fuselage, are equipped with mechanically linked movable flaps. A rigid control link connects them to the main wing's aileron / camber mixer system ([Fig. 5]). This combined aileron / camber function is called a flaperon. The main wings are equipped with dual-function flaps: roll control and lift enhancement through positive or negative deflection. A control system allows for differential deflection of each aileron / curve. The camber flap function is controlled by an electric actuator operated by the pilot. The various flaperon deflections affect the canard flaps via the aforementioned rigid control. Given the canard's lift ratio to that of the main wings (15%), the canard flap deflection is equal to 50% of the flaperon deflection. This system allows the aircraft to maintain natural balance across its entire speed range. The elevator, located at the rear of the horizontal stabilizer, is used for pitch control of the aircraft. It consists of two mechanically linked flaps operated by the pilot via a rigid control. At the trailing edge of the The flaps consist of two movable surfaces (tab). These two surfaces, through their actions, reduce the effort required on the elevator control. The elevator is controlled by the control stick. This is connected to a first horizontal control rod. This rod transmits the movement to a vertical rod via a first control horn. This second control rod, installed in the vertical stabilizer, is weighted with a mass known as a G-compensator. This second control rod is connected to a third rod via a control horn. This third rod is connected to the two flaps that make up the elevator ([Fig. 7]). In the presence of strong turbulence, the aircraft pitches up and increases its angle of attack, and its load factor increases. The weighted vertical rod, under the action of the positive acceleration, moves in the direction opposite to the load factor.This movement results in a forward force applied to the control stick and a downward movement of the elevator. This elevator deflection increases the lift of the horizontal stabilizer, which reduces the load factor and brings the aircraft back to level flight. This weighted rod, known as the G-compensator, is an important element for stabilizing the aircraft in highly turbulent airflow. The fin is positioned at the rear of the vertical stabilizer and is operated by the pilot via a cable system connected to the rudder pedals. This control is coupled to the steerable and conjugate nose landing gear system. This aircraft can be flown by a pilot acting on the flight controls or flown by an electronic computer controlled from a ground station or in total autonomy. Stability and control command. The position of the three control surfaces, combined with the various settings of the movable flaps, allows for a flight configuration where all lift vectors are positive. This combination is achieved by a mechanical mixing system without any specific pilot action other than adjusting the flap camber and elevator trim. The three upward-pointing lift vectors ensure very high aircraft stability, particularly in gusts or severe turbulence ([Fig. 4]). Propulsion description. Different types of propulsion are possible on this aircraft: 1) The propeller is positioned at the rear of the fuselage and absorbs the fuselage boundary layer to minimize tail drag. A driveshaft connects the crankshaft to the Piston engine with a single bearing attached to the fuselage. The constant speed propeller is fixed to this bearing. The intake of air for supplying and cooling the engine is ensured by two air intakes positioned on either side of the fuselage upstream of the main wings and below the canard line in a favorable pressure zone. 2) Propulsion can be provided by one or two turboshaft engines driving a single propeller or two contra-rotating propellers. 3) The aircraft can be powered by a turbojet engine. The exhaust nozzle is located at the rear of the fuselage in place of the propeller. 4) The aircraft can be propelled by one or two electric motors driving a single propeller or two contra-rotating propellers. Description of the landing gear system. The landing gear is a tricycle design, with one main gear at the front and two main gears positioned under the wings. These gears have integrated hydraulic shock absorbers. The extension and retraction of the landing gear is controlled by a hydraulic pump driven by an electric motor. A programmable logic controller (PLC) manages the opening and closing cycle of the landing gear doors. Description of the manufacturing technology The three-surface aircraft is made entirely of composite material based on carbon fibers and resin. List of figures
[0004] Other features and advantages of the invention will become apparent from reading the detailed description that follows, with reference to the figures, which illustrate: [Fig.1]: Front view of the aircraft. [Fig.2]: Side view of the aircraft. [Fig.3]: Top view of the aircraft. [Fig.4]: Forces exerted on the aircraft during cruise. [Fig.5]: Forces exerted on the aircraft during takeoff. [Fig.6]: Control diagram for canard flaps and flaperons. [Fig.7]: Control diagram for the elevator flaps. Figures 1, 2, and 3 show the canard (1), the main wing (2), the rear lifting surface (3), the vertical stabilizer (4), and the stabilizing fins (5). The canard flaps are shown in (6), the flaperons in (7), and the elevator in (8). (8), the fin in (9), the fuselage in (10). The air intakes are shown in (11), the nose landing gear in (12), the right main landing gear in (13) and the left main landing gear in (14). The propeller is shown in (15). Figure 6 shows the canard and flaperon control scheme. The flaperon and canard linkage rod is shown in (17), the flaperon and canard actuator or cylinder is shown in (16), and the linkage rod control linkage is shown in (18). The flaperon control rod is shown in (19). The canard control linkage is shown in (20), and the canard control rod is shown in (21). The canard tail is shown in (1), the canard flap in (6). The main wing is shown in (2), the flaperon in (7). Figure 7 shows the elevator control scheme (8). The horizontal stabilizer is shown in (3) and the fin in (4) and the rudder in (9). Also shown in this figure are: the control stick or steering control (25), the first horizontal elevator control rod in (24), the rudder return control horn in (23), the second vertical elevator control rod and its G-balancing weight in (22), the elevator horn in (26), the third elevator control rod in (27).
Claims
Demands
1. Three-wing aircraft comprising a main wing (2), an upstream wing (1) located above the main wing (2), and a downstream wing (3) located above the other two, these three wing surfaces (1, 2, 3) comprising movable flaps (6, 7, 8) and a rigid control linkage (21, 17, 19), between the movable flaps of the upstream wing (6) and the movable flaps of the main wing (7), wherein a deflection angle of the movable flaps of the upstream wing (6) is equal to 50% of the deflection angle of the movable flaps of the main wing (7), wherein at takeoff the lift components of the aerodynamic forces acting on the respective wing are distributed as follows: F1 = 0.15g, F2 = 0.95g, F3 = -0.1g, and wherein in cruise the lift components of the Aerodynamic forces are distributed as follows: Fl= 0.1 g, F2=0.75g, F3=0.15g.
2. Three-surface aircraft according to claim 1 characterized by the installation of two stabilizing fins (5) positioned under the rear of the fuselage (10) at an angle of 30° on either side of the fuselage.
3. Three-surface aircraft according to claims 1 and 2 characterized by a downstream lifting surface (3) with an inverted profile relative to the other two lifting surfaces (1) and (2), a movable flap (8) being connected to this lifting surface, this downstream lifting surface having positive lift in cruise and negative lift during takeoff or during angle of attack.
4. Three-surface aircraft according to claims 1 and 2 and 3 characterized by a propulsion system consisting of a multi-bladed propeller driven by a piston engine housed in the rear part of the fuselage (10).
5. Three-surface aircraft according to claims 1 and 2 and 3 characterized by a propulsion system consisting of a multi-bladed propeller driven by one or two turboshaft engines.
6. Three-surface aircraft according to claims 1 and 2 and 3 characterized by a propulsion system consisting of two counter-rotating propellers driven by one or two turboshaft engines.
7. Three-surface aircraft according to claims 1 and 2 and 3 characterized by a propulsion system composed of a turbojet engine.
8. Three-surface aircraft according to claims 1 and 2 and 3 characterized by a propulsion system consisting of one or two electric motors driving a single propeller or two contra-rotating propellers.