A method for verifying the take-off and landing speed of a non-reversible propeller amphibious aircraft

Abstract

The present application relates to the technical field of aircraft design, and particularly relates to a take-off and landing point speed airworthiness verification method of an engine non-reversible propeller amphibious aircraft. The minimum steady taxiing speed V L and the turning radius R are determined through water test, and a turning area is arranged at both ends of the water runway; when taking off, the aircraft enters the turning area at a speed not greater than V L to implement low-speed turning alignment and then accelerates to leave water; when decelerating, the aircraft decelerates to a speed not greater than V L to enter the turning area to implement turning and energy dissipation; the distance of the turning section is counted into performance data, and the maximum value of multiple tests is taken to ensure data conservativeness, stability and consistency, and finally, the related requirements are solidified into a standardized operation procedure. The present application uses low-speed turning to equivalently replace the static point, meets the airworthiness requirements, and ensures that the test and operation process is repeatable, reviewable and traceable.

Description

Technical Field

[0001] This invention relates to the technical field of aircraft design, specifically to a method for verifying the airworthiness of takeoff and landing speeds of an engine-driven, anti-reverse propeller-less amphibious aircraft. Background Technology

[0002] Current airworthiness regulations and special conditions set forth clear requirements for the performance testing and data determination of amphibious aircraft during takeoff, landing, and water-lifting missions. They stipulate that the takeoff roll start point, the landing roll end point, and the termination point of aborted takeoff (acceleration-stop) or aborted water-lifting tests must all be in a relatively stationary state, typically requiring a speed of around 3 knots. For example, CCAR Part 25, Clause 25.125 requires the landing distance to be determined as "the horizontal distance required from 15 meters (50 feet) above the landing surface to a complete stop (approximately 3 knots for water-lifting)." Under this requirement, the aircraft must be essentially stopped or reach a very low speed at the runway end before initiating takeoff or completing deceleration to ensure the accuracy of performance data and the controllability of the testing process. This regulation aims to standardize the start and end states of testing, eliminate the influence of initial speed differences on performance distance calculations, and ensure the safety boundaries for aircraft operation within the water runway area.

[0003] However, for amphibious aircraft whose engines lack anti-rotation propellers, deceleration methods on the water surface are limited. These aircraft cannot generate reverse thrust through propeller counter-rotation; deceleration on the water surface primarily relies on reducing the throttle to idle and using hydrodynamic drag for natural slowdown. This method is inefficient, and in actual operation, it is often difficult to reduce the speed to the relatively stationary state required by regulations. In restricted waters or under specified runway widths and lengths, the lack of effective measures to ensure the aircraft reaches a stable and controllable low speed at the takeoff and landing points will directly lead to failure to meet airworthiness requirements. Furthermore, because takeoff and landing speeds are not repeatable and difficult to control stably, performance data exhibits increased variability, affecting data consistency and reliability, and potentially increasing the risk of the aircraft skidding out of the safe zone of the runway, adversely impacting both testing and operational safety. Summary of the Invention

[0004] To address the challenge of amphibious aircraft without counter-rotating engines struggling to decelerate to a relatively stationary state (around 3 knots) on water, this invention proposes an airworthiness verification method for takeoff and landing speeds. This method replaces the "takeoff and landing stationary point" with an equivalent "low-speed turning maneuver," obtaining conservative, stable, and consistent data on water takeoff, aborted takeoff, aborted water intake, and water landing performance. It also ensures that the aircraft remains within the safe range of the water runway throughout the entire testing and operation process, thus providing a safety level equivalent to regulations.

[0005] To achieve the above objectives, the present invention specifically adopts the following solution: A method for verifying the takeoff and landing speeds of an engine-driven, non-reverse-rotor amphibious aircraft, comprising: Low-speed threshold and turning capability test: The minimum stable gliding speed VL was determined through water tests, and the turning radius R was measured through turning tests under different maneuvers; Turning area setup for water track: Clearly marked turning areas are set up at both ends of the water track; Water surface takeoff starting point equivalent: the aircraft starts at a speed not exceeding V. L The aircraft enters the turning zone at high speed, uses water rudder deflection and / or differential thrust to perform a low-speed turn, and accelerates straight out of the water along the runway centerline after completing the heading alignment. Equivalent to the water surface deceleration termination point: After the aircraft decelerates on the water surface, it decelerates to a value not greater than V. L At a speed of [speed value], the aircraft enters the runway end turning area and again uses water rudder deflection and differential thrust to perform a low-speed turn, allowing the aircraft to continue dissipating energy within the safe range of the runway; the water surface deceleration includes different operating conditions such as the aircraft touching the water, aborting takeoff, or aborting wading. Takeoff or deceleration distance included: The turning distance and acceleration taxiing distance before takeoff are included in the water takeoff distance, and the deceleration taxiing distance and turning distance of the aircraft on the water are included in the water deceleration distance. Conservative and consistency measures: The distance of the turning section was repeatedly tested under different conditions, and the maximum value was included in the corresponding total distance.

[0006] Furthermore, it also includes the standardization of airworthiness procedures: the entry conditions, control techniques, runway end entry point location, marking requirements, and configuration requirements for each stage of the low-speed turning maneuver are solidified into standardized operating procedures in flight manuals or test outlines, so that the test and operation process is repeatable, auditable, and traceable.

[0007] Furthermore, the minimum stable coasting speed V L The minimum stable taxiing speed V was determined through multiple straight-line taxiing tests with the landing gear retracted, in standard configuration, and under engine idle conditions. L It can be determined according to the model.

[0008] Furthermore, the conservatism and consistency treatment specifically includes: Increase speed to V L The water takeoff process is divided into an initial turning phase and an acceleration taxiing phase, with the starting point of straight-line travel as the dividing line. The distance of the initial turning phase is included in the water takeoff distance. Reduce speed to V LThe process of landing on water, aborting takeoff, or aborting wading is divided into a deceleration taxiing phase and a termination turning phase, with the starting point of the turning phase as the dividing line. The distance of the termination turning phase is included in the water surface deceleration distance for landing on water, aborting takeoff, or aborting wading. The starting and ending slewing distances were tested multiple times under different weight, center of gravity, wind and waves, and operator conditions, and the maximum values ​​were included in the corresponding total distances to ensure the conservatism and consistency of the performance data.

[0009] Furthermore, the radius of gyration R includes: The first turning radius R1 is determined by the speed V. L The nearby tests and measurements were conducted solely using full-deflection water rudder maneuvers. The second turning radius R2 is determined by the speed V. L Nearby, a gyratory test was conducted using a water rudder with full deflection and the differential thrust of multiple engines. R1 and R2 are used to prove that low-speed turns can be performed within the specified width of the water runway, and the maximum value of the first turning radius R1 and the second turning radius R2 is taken as the final turning radius R; The turning radius R can be determined according to the model.

[0010] Furthermore, the turning area is distinguished from the runway boundary by buoys of different colors or shapes, and the markings include at least: entry markings, boundary markings, and termination line markings.

[0011] Furthermore, in the equivalent step of the water surface takeoff starting point, after the aircraft completes the turn and alignment, it reaches the starting line position to complete the takeoff configuration setting, and pushes to the takeoff power at a certain distance in front to accelerate in a straight line and leave the water; the takeoff configuration setting includes placing the flaps in the takeoff position.

[0012] Furthermore, in the equivalent step of the water surface deceleration termination point, the aircraft reduces its speed to no more than V. L At that time, ensure that you reach the finish line mark on the runway just in time before entering the finish line turning area to perform the turn.

[0013] Compared with the prior art, the present invention has the following beneficial technical effects: This invention predetermines the minimum stable taxiing speed and turning radius of the aircraft, and sets up clearly marked turning areas at both ends of the water runway. This allows the aircraft to perform controlled low-speed turns using water rudder deflection and differential thrust when the speed is not greater than a certain value. Thus, without adding anti-rotation propellers or special deceleration devices, it meets the relevant requirements of airworthiness regulations for take-off and end-point speeds in an equivalent manner, eliminating compliance obstacles caused by the inability to come to a complete stop.

[0014] The data's conservatism, stability, and consistency are ensured through segmentation and extreme value handling. Regarding segmentation, V... L As a unified dividing point, the takeoff and deceleration processes are divided into turning and straight sections, clearly defining the start and end boundaries of each section. This eliminates data discrepancies caused by inconsistent judgment standards for "takeoff and end states" under different operators and operating conditions, providing a unified benchmark for performance distance calculations and thus improving data consistency and stability. Regarding extreme value handling, the turning section distance is repeatedly tested under different weight, center of gravity, wind, wave, and operator conditions, and the maximum value is used in the total distance calculation, rather than using the average value or a single test value. This ensures that the final performance data covers the most unfavorable operating condition combination, resulting in a conservative result with a safety margin, meeting the data conservatism requirements for airworthiness certification.

[0015] The entry conditions, control techniques, runway end entry point location, marking requirements, and configuration requirements for low-speed turning maneuvers are solidified into standardized operating procedures in flight manuals or test outlines, ensuring the repeatability, auditability, and traceability of the testing and operation process. This method transforms maneuvering operations, which originally relied on pilot experience, into a procedural and standardized airworthiness verification process. It is not only applicable to the airworthiness compliance verification of amphibious aircraft without anti-rotor engines under different operating conditions such as water takeoff, aborted takeoff, aborted water intake, and water landing, but also has type universality and can be extended to multi-engine propeller or turboprop types of amphibious aircraft without anti-rotor capabilities and with limited deceleration on the water surface. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the takeoff process according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the water contact / interruption deceleration process in a specific embodiment of the present invention. Detailed Implementation

[0017] In this specific embodiment, an amphibious aircraft whose engine does not have a reverse propeller function will be used as an example for illustration.

[0018] First, capability verification is performed. The minimum stable taxiing speed VL is determined as follows: with the landing gear retracted, in standard configuration (e.g., flaps at 0°), and the engine at idle, multiple straight taxiing tests are conducted, and the minimum speed at which the aircraft can maintain stable control is recorded. VL is determined through these tests. L No more than 20 km / h, the specific value can be determined according to the aircraft model.

[0019] The method for determining the low-speed turning radius is as follows: near the speed VL, turn tests are conducted using two control methods: full deflection of the water rudder alone and full deflection of the water rudder combined with differential thrust from multiple engines. The range of the first turning radius R1 and the second turning radius R2 is measured. For example, the turning radius range can be determined according to the aircraft type and is on the order of 70 to 150 m. The maximum value of R1 and R2 is taken as the final turning radius R, which is used to prove that low-speed turning can be implemented within the specified width of the water runway.

[0020] Next, the water runway and turning area are set up. Turning areas are set up at both ends of the water runway, and buoys of a different color than the runway boundary are deployed inside the runway safety area to mark the entry point of the turning area, the boundary of the turning trajectory, and the end line, ensuring that pilots can accurately enter the turn at low speeds. The turning area is distinguished from the runway boundary by buoys of different colors or shapes, and the markings include at least entry markings, boundary markings, and end line markings.

[0021] Please see Figure 1 The specific implementation method for water-based takeoff procedures and equivalent starting points is as follows: The takeoff course and runway usage direction are planned based on wind direction and speed. The aircraft enters the runway end turning area from the taxiway, with a speed not exceeding V... L Under these conditions, the aircraft employs water rudder deflection and differential control of the left and right engine thrust to perform a low-speed turn maneuver, enabling it to adjust its course and enter the runway safety area. After completing the turn, the aircraft aligns with the runway centerline and completes the takeoff configuration setup upon reaching the starting line, such as placing the flaps in the takeoff position and accelerating to takeoff power along the centerline at a certain distance ahead to accelerate away from the water. The initial turn distance before establishing takeoff power is included in the water surface takeoff distance; the initial turn distance includes the alignment taxiing distance before entering the turn and the turn arc length.

[0022] Please see Figure 2 The specific implementation method for the water-landing or abort procedure and termination point is as follows: After the aircraft lands on water, aborts takeoff, or aborts water intake, it immediately reduces the throttle to idle and utilizes hydrodynamic drag to decelerate during the first moment of stable taxiing. As the speed decreases, configuration adjustments such as flap retraction and propeller restraint release are gradually completed according to the aircraft manual or test outline. When the speed decreases to no more than V... L At the same time, ensure that the aircraft reaches the runway end line mark and then enters the end-point turning zone. Use water rudder deflection and differential thrust to perform a low-speed turn, allowing the aircraft to continue dissipating energy along the controlled trajectory and maintain the runway safety range. The deceleration straight section and the end-point turning section are included in the water-landing distance, water-drawing interruption distance, and takeoff interruption distance. The end-point turning section distance includes the taxiing distance required to decelerate and enter the turn, as well as the distance corresponding to the turning arc length or turning diameter.

[0023] Then, conservative and consistency measures are implemented: the speed is increased to V. LThe water takeoff process is divided into an initial turn phase and an acceleration taxiing phase, with the starting point of straight-line travel as the dividing line. The distance of the initial turn phase is included in the water takeoff distance. The speed decreases to V... L The starting point of the turn is used as the dividing line, and the process of different operating conditions such as water landing, aborted takeoff, or aborted water intake is divided into a deceleration taxiing phase and a final turn phase. The distance of the final turn phase is included in the water surface deceleration distance for the corresponding operating condition. The starting and final turn phase distances are repeatedly tested under different weight, center of gravity, wind and wave conditions, and operator conditions, and the maximum value is included in the corresponding total distance to ensure the conservatism and consistency of performance data.

[0024] Finally, the process is formalized and solidified: the entry conditions, control techniques, runway end entry point location, marking requirements, and configuration requirements for each stage of the low-speed turning maneuver are solidified into standardized operating procedures in the flight manual or test outline, so that the test and operation process is repeatable, auditable, and traceable.

[0025] The parameter examples used in this specific embodiment are for illustrative purposes only and do not limit the scope of protection of this invention with any specific model or parameter. The method of this invention is applicable to amphibious aircraft with multi-engine propellers or turboprops, engines without anti-rotation function, and limited water surface deceleration capability.

Claims

1. A method for verifying the airworthiness of takeoff and landing speeds of an amphibious aircraft without a counter-rotor engine, characterized in that, include: Low-speed threshold and turning capability test: Determine the minimum stable gliding speed V through water tests. L And the radius of gyration R was measured by gyration tests under different operating conditions; Turning area setup for water track: Clearly marked turning areas are set up at both ends of the water track; Water surface takeoff starting point equivalent: the aircraft starts at a speed not exceeding V. L The aircraft enters the turning zone at high speed, uses water rudder deflection and / or differential thrust to perform a low-speed turn, and accelerates straight out of the water along the runway centerline after completing the heading alignment. Equivalent to the water surface deceleration termination point: After the aircraft decelerates on the water surface, it decelerates to a value not greater than V. L At a speed of [speed value], the aircraft enters the runway end turning area and again uses water rudder deflection and differential thrust to perform a low-speed turn, allowing the aircraft to continue dissipating energy within the safe range of the runway; the water surface deceleration includes different operating conditions such as the aircraft touching the water, aborting takeoff, or aborting wading. Takeoff or deceleration distance included: The turning distance and acceleration taxiing distance before takeoff are included in the water takeoff distance, and the deceleration taxiing distance and turning distance of the aircraft on the water are included in the water deceleration distance. Conservative and consistency measures: The distance of the turning section was repeatedly tested under different conditions, and the maximum value was included in the corresponding total distance.

2. The method for verifying the airworthiness of the takeoff and landing speeds of an engine-less amphibious aircraft according to claim 1, characterized in that, Also includes: Airworthiness proceduralization: The entry conditions, control techniques, runway end entry point location, marking requirements, and configuration requirements for each stage of the low-speed turning maneuver are solidified into standardized operating procedures in the flight manual or test outline, so that the test and operation process is repeatable, auditable, and traceable.

3. The method for verifying the airworthiness of the takeoff and landing speeds of an engine-less amphibious aircraft according to claim 1, characterized in that, The minimum stable gliding speed V L The minimum stable taxiing speed V was determined through multiple straight-line taxiing tests with the landing gear retracted, in standard configuration, and under engine idle conditions. L It can be determined according to the model.

4. The method for verifying the airworthiness of takeoff and landing speeds of an engine-less amphibious aircraft according to claim 1, characterized in that, Conservatism and consistency processing specifically include: Increase speed to V L The water takeoff process is divided into an initial turning phase and an acceleration taxiing phase, with the starting point of straight-line travel as the dividing line. The distance of the initial turning phase is included in the water takeoff distance. Reduce speed to V L The process of landing on water, aborting takeoff, or aborting wading is divided into a deceleration taxiing phase and a termination turning phase, with the starting point of the turning phase as the dividing line. The distance of the termination turning phase is included in the water surface deceleration distance for landing on water, aborting takeoff, or aborting wading. The starting and ending slewing distances were tested multiple times under different weight, center of gravity, wind and waves, and operator conditions, and the maximum values ​​were included in the corresponding total distances to ensure the conservatism and consistency of the performance data.

5. The method for verifying the airworthiness of the takeoff and landing speeds of an engine-less amphibious aircraft according to claim 1, characterized in that, The radius of gyration R includes: The first turning radius R1 is determined by the speed V. L The nearby tests and measurements were conducted solely using full-deflection water rudder maneuvers. The second turning radius R2 is determined by the speed V. L Nearby, a gyratory test was conducted using a water rudder with full deflection and the differential thrust of multiple engines. R1 and R2 are used to prove that low-speed turns can be performed within the specified width of the water runway, and the maximum value of the first turning radius R1 and the second turning radius R2 is taken as the final turning radius R; The turning radius R can be determined according to the model.

6. The method for verifying the airworthiness of the takeoff and landing speeds of an engine-less amphibious aircraft according to claim 1, characterized in that, The turning area is distinguished from the runway boundary by buoys of different colors or shapes, and the markings include at least: entry markings, boundary markings, and termination line markings.

7. The method for verifying the airworthiness of the takeoff and landing speeds of an engine-less amphibious aircraft according to claim 1, characterized in that, In the equivalent steps of the water surface takeoff starting point, after the aircraft completes the turn and alignment, it reaches the starting line position to complete the takeoff configuration setting, and pushes to the takeoff power at a certain distance in front to accelerate in a straight line and leave the water; the takeoff configuration setting includes placing the flaps in the takeoff position.

8. The method for verifying the airworthiness of the takeoff and landing speeds of an engine-driven, non-reverse-propeller amphibious aircraft according to claim 1, characterized in that, In the equivalent step of the water surface deceleration termination point, the aircraft reduces its speed to no more than V. L At that time, ensure that you reach the finish line mark on the runway just in time before entering the finish line turning area to perform the turn.

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