Method for determining flight performance of helicopter through test flight data

Abstract

The invention belongs to the technical field of helicopter design, and particularly relates to a method for determining the flight performance of a helicopter through test flight data. The method comprises the following steps: obtaining power required for hovering according to hovering test flight data; according to the variable-height level flight test flight data, determining the level flight required power, and in the variable-height level flight process, keeping the conversion weight of the helicopter unchanged by adjusting the flight height; determining the climbing efficiency according to the sawtooth climbing test flight data, and determining the climbing required power; engine installation loss is determined according to hovering, level flight and climbing test flight data, and therefore the available power of the helicopter is determined; and determining the flight performance according to the required power and the available power of the helicopter in the states of hovering, level flight and climbing.

Description

Technical Field

[0001] The invention belongs to the technical field of helicopter design, and in particular relates to a method for determining helicopter flight performance through test flight data. Background Art

[0002] During the civil helicopter airworthiness verification process, regulations require that the helicopter flight performance be given. The helicopter flight performance is obtained by balancing the required power and available power. The required power of the helicopter is the power consumed to maintain the hovering, level flight, and climbing state; the available power of the helicopter is the minimum output power of the engine after considering the installation loss. In addition, during the test flight, as the fuel is consumed, the weight of the helicopter gradually decreases and deviates from the target weight, resulting in the need to eliminate the influence of weight error during the test flight process. Traditional test flight data processing methods generally use performance calculation software to correct weight errors, but since the use of performance calculation software will introduce uncertainty errors, it does not meet the civil helicopter airworthiness verification requirements. Summary of the invention

[0003] To solve the above problems, the present invention provides a method for determining the flight performance of a helicopter through test flight data. The required power and available power of the helicopter under different states are determined through hovering, level flight and climbing test flight data. The flight performance of the helicopter is directly determined based on the test flight data to meet the airworthiness certification requirements.

[0004] In order to achieve the above object, the present invention adopts the following technical solution to achieve it.

[0005] A method for determining helicopter flight performance through test flight data, the method comprising:

[0006] S1, obtain the hovering power required according to the hovering test flight data;

[0007] S2, determining the power required for level flight according to the variable altitude level flight test data, wherein during the variable altitude level flight, the helicopter converted weight is kept unchanged by adjusting the flight altitude;

[0008] S3, determine the climb efficiency and the power required for the climb based on the sawtooth climb test flight data;

[0009] S4, determine the engine installation loss based on hover, level flight and climb test flight data, thereby determining the helicopter's available power;

[0010] S5, determine the flight performance based on the helicopter's required power and available power in hover, level flight, and climb conditions.

[0011] Furthermore, S1 is specifically:

[0012] The relationship curve between the converted weight and converted power is determined through hovering test flight data in plains, plateaus and high altitudes. The hovering power required at any altitude, temperature and weight can be obtained through interpolation.

[0013] Helicopter conversion weight = helicopter measured weight × δ 目标 / δ×((N R额定 ) / N R )^2;

[0014] Helicopter conversion power = helicopter measured power × δ 目标 / δ×((N R额定 ) / N R )^3;

[0015] δ is the measured atmospheric density ratio, δ 目标 is the density ratio under standard atmosphere, N R is the measured rotor speed, N R额定 is the rated rotor speed.

[0016] Furthermore, S2 is specifically:

[0017] S21, setting the target altitude and initial target weight of the helicopter for level flight;

[0018] S22, obtaining variable altitude test flight data while keeping the helicopter converted weight unchanged, and obtaining a relationship curve between level flight speed and required power;

[0019] S23, changing the target weight at the target altitude, repeating S22, and obtaining a relationship curve between the level flight speed and the required power at different target weights at the target altitude;

[0020] S23, changing the target altitude of the helicopter for level flight, repeating S22-S23 at the target altitude of the helicopter for level flight and the initial target weight, to obtain a relationship curve between the level flight speed and the required power at different target altitudes and target weights;

[0021] S24, through interpolation, the power required for level flight at any altitude, temperature, weight and speed can be obtained.

[0022] Furthermore, S3 is specifically:

[0023] Determine the power required for climbing: Determine the climbing efficiency through sawtooth climb test data at different altitudes and weights;

[0024] The calculation method of climb efficiency is:

[0025] Climb efficiency = (measured helicopter weight × 9.8 × measured climb rate) / (measured helicopter power – power required for level flight)

[0026] The power required for level flight is calculated according to the power required for level flight method mentioned above;

[0027] By collecting statistics on the climb efficiency data, we can determine the climb efficiency curve that changes with speed. Combined with the required power for level flight determined above, the required power for climb at any altitude, temperature, weight, speed and climb rate can be obtained through interpolation.

[0028] Furthermore, S4 is specifically:

[0029] The engine bench power at the corresponding altitude and temperature is obtained through the altitude, temperature and engine control parameters in the hover, level flight and climb test flight data, as well as the engine bench performance; the engine bench performance represents the relationship between the engine control parameters and the engine output power when the engine leaves the factory;

[0030] Compare the engine bench power with the measured engine power to determine the engine installation loss in hover, level flight and climb conditions;

[0031] The available power of the helicopter is determined based on the minimum guaranteed performance of the engine at different altitudes and temperatures, as well as the engine installation losses in hovering, level flight and climbing conditions. The minimum guaranteed performance of the engine represents the minimum power that can be output during the entire life cycle of the engine, and the available power of the helicopter at different altitudes and temperatures in hovering, level flight and climbing conditions is obtained.

[0032] Furthermore, engine installation loss = (engine bench power - engine measured power) / engine bench power.

[0033] Furthermore, the helicopter's available power = the engine's minimum guaranteed performance * (1-engine installation loss).

[0034] Furthermore, S5 is specifically:

[0035] Determine the helicopter flight performance: The required power and available power for hovering, level flight and climbing states determined above can be used to determine the helicopter flight performance by balancing the two. The helicopter flight performance includes the weight, speed and climb rate that the helicopter can achieve at a specific altitude and temperature.

[0036] The technical solution of the present invention provides a method for determining helicopter performance through test flight data. According to the hovering, level flight, and climbing test flight data at a specific altitude, temperature, and weight, the required power for hovering, level flight, and climbing in any state is determined through interpolation calculation; the available power in the hovering, level flight, and climbing state is determined according to the engine bench performance, and the required power and available power are calculated to determine the helicopter flight performance. In the above data processing process, there is no need to use performance calculation software to correct the weight error caused by fuel consumption during the test flight, and a more accurate flight performance calculation result can be obtained to meet the requirements of airworthiness verification. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described in detail below.

[0038] An embodiment of the present invention provides a method for determining helicopter performance through test flight data, comprising:

[0039] 1) Obtain the hovering power required based on the hovering test flight data;

[0040] The relationship curve between the converted weight and converted power is determined through hovering test flight data in plains, plateaus and high altitudes. The hovering power required at any altitude, temperature and weight can be obtained through interpolation.

[0041] Helicopter conversion weight = helicopter measured weight × δ 目标 / δ×((N R额定 ) / N R )^2;

[0042] Helicopter conversion power = helicopter measured power × δ 目标 / δ×((N R额定 ) / N R )^3;

[0043] δ is the measured atmospheric density ratio, δ 目标 is the density ratio under standard atmosphere, N R is the measured rotor speed, N R额定 is the rated rotor speed;

[0044] 2) determining the power required for level flight based on the variable altitude level flight test data, wherein during the variable altitude level flight, the helicopter converted weight is kept unchanged by adjusting the flight altitude;

[0045] S21, setting the target altitude and initial target weight of the helicopter for level flight;

[0046] S22, obtaining variable altitude test flight data while keeping the helicopter converted weight unchanged, and obtaining a relationship curve between level flight speed and required power;

[0047] S23, at the target altitude, changing the target weight, repeating S22, to obtain a relationship curve between the level flight speed and the required power at different target weights at the target altitude;

[0048] S23, changing the target altitude of the helicopter for level flight, repeating S22-S23 at the target altitude of the helicopter for level flight and the initial target weight, to obtain a relationship curve between the level flight speed and the required power at different target altitudes and target weights;

[0049] S24, through interpolation, the required power for level flight at any altitude, temperature, weight and speed can be obtained;

[0050] Taking a twin-engine civil helicopter as an example, the variable altitude level flight test flight status is shown in the table below, covering light weight to heavy weight, low altitude to high altitude. The required power curve for level flight in the following states is determined based on the test flight data, and the required power for level flight at any altitude, temperature, weight, and speed can be obtained by interpolation;

[0051]

[0052] 3) Determine the climb efficiency based on the sawtooth climb test flight data and further determine the power required for the climb;

[0053] Determine the power required for climb: Determine the climb efficiency through sawtooth climb test data at different altitudes and weights.

[0054] The calculation method of climb efficiency is:

[0055] Climb efficiency = (measured helicopter weight × 9.8 × measured climb rate) / (measured helicopter power – power required for level flight)

[0056] The power required for level flight is calculated according to the power required for level flight method mentioned above;

[0057] By collecting statistics on the climb efficiency data, the climb efficiency curve that changes with speed is determined. Combined with the required power for level flight determined above, the required power for climb under any altitude, temperature, weight, speed and climb rate can be obtained by interpolation.

[0058] 4) Determine the engine installation loss based on hover, level flight and climb test flight data, thereby determining the helicopter's available power;

[0059] The engine bench power at the corresponding altitude and temperature is obtained through the altitude, temperature and engine control parameters in the hover, level flight and climb test flight data, as well as the engine bench performance; the engine bench performance represents the relationship between the engine control parameters and the engine output power when the engine leaves the factory;

[0060] Compare the engine bench power with the measured engine power to determine the engine installation loss in hover, level flight and climb conditions;

[0061] Engine installation loss = (engine bench power - engine measured power) / engine bench power;

[0062] The helicopter's available power is determined based on the engine's minimum guaranteed performance at different altitudes and temperatures, as well as the engine installation loss in hovering, level flight, and climbing states; the engine's minimum guaranteed performance represents the minimum power that can be output during the engine's entire life cycle. Helicopter available power = engine's minimum guaranteed performance * (1-engine installation loss), and the helicopter's available power at different altitudes and temperatures in hovering, level flight, and climbing states is obtained.

[0063] 5) Determine the flight performance based on the helicopter's required power and available power under different conditions.

[0064] Determine the helicopter flight performance: The required power and available power for hovering, level flight and climbing states determined above can be used to determine the helicopter flight performance by balancing the two. The helicopter flight performance includes the weight, speed and climb rate that the helicopter can achieve at a specific altitude and temperature.

[0065] The technical solution of the present invention provides a method for determining helicopter performance through test flight data. According to the hovering, level flight, and climbing test flight data at a specific altitude, temperature, and weight, the required power for hovering, level flight, and climbing in any state is determined through interpolation calculation; the available power in the hovering, level flight, and climbing state is determined according to the engine bench performance, and the required power and available power are calculated to determine the helicopter flight performance. In the above data processing process, there is no need to use performance calculation software to correct the weight error caused by fuel consumption during the test flight, and a more accurate flight performance calculation result can be obtained to meet the requirements of airworthiness verification.

Claims

1. A method for determining helicopter flight performance through test flight data, characterized in that: The method comprises: S1, obtain the hovering power required according to the hovering test flight data; S2, determining the power required for level flight according to the variable altitude level flight test data, wherein during the variable altitude level flight, the helicopter converted weight is kept unchanged by adjusting the flight altitude; S3, determine the climb efficiency and the power required for the climb based on the sawtooth climb test flight data; S4, determine the engine installation loss based on hover, level flight and climb test flight data, thereby determining the helicopter's available power; S5, determine the flight performance based on the helicopter's required power and available power in hover, level flight, and climb conditions.

2. A method for determining helicopter flight performance through test flight data according to claim 1, characterized in that: S1 is specifically: The relationship curve between the converted weight and converted power is determined through hovering test flight data in plains, plateaus and high altitudes. The hovering power required at any altitude, temperature and weight can be obtained through interpolation. Helicopter conversion weight = helicopter measured weight × δ 目标 / δ×((N R额定 ) / N R )^2; Helicopter conversion power = helicopter measured power × δ 目标 / δ×((N R额定 ) / N R )^3; δ is the measured atmospheric density ratio, δ 目标 is the density ratio under standard atmosphere, N R is the measured rotor speed, N R额定 is the rated rotor speed.

3. The method for determining helicopter flight performance through test flight data according to claim 2, characterized in that: S2 is specifically: S21, setting the target altitude and initial target weight of the helicopter for level flight; S22, obtaining variable altitude test flight data while keeping the helicopter converted weight unchanged, and obtaining a relationship curve between level flight speed and required power; S23, changing the target weight at the target altitude, repeating S22, and obtaining a relationship curve between the level flight speed and the required power at different target weights at the target altitude; S23, changing the target altitude of the helicopter for level flight, repeating S22-S23 at the target altitude of the helicopter for level flight and the initial target weight, to obtain a relationship curve between the level flight speed and the required power at different target altitudes and target weights; S24, through interpolation, the power required for level flight at any altitude, temperature, weight and speed can be obtained.

4. The method for determining helicopter flight performance through test flight data according to claim 3, characterized in that: S3 is specifically: Determine the power required for climbing: Determine the climbing efficiency through sawtooth climb test data at different altitudes and weights; The calculation method of climb efficiency is: Climb efficiency = (measured helicopter weight × 9.8 × measured climb rate) / (measured helicopter power – power required for level flight) The power required for level flight is calculated according to the power required for level flight method mentioned above; By collecting statistics on the climb efficiency data, we can determine the climb efficiency curve that changes with speed. Combined with the required power for level flight determined above, the required power for climb at any altitude, temperature, weight, speed and climb rate can be obtained through interpolation.

5. The method for determining helicopter flight performance through test flight data according to claim 4, characterized in that: S4 is specifically: The engine bench power at the corresponding altitude and temperature is obtained through the altitude, temperature and engine control parameters in the hover, level flight and climb test flight data, as well as the engine bench performance; the engine bench performance represents the relationship between the engine control parameters and the engine output power when the engine leaves the factory; Compare the engine bench power with the measured engine power to determine the engine installation loss in hover, level flight and climb conditions; The available power of the helicopter is determined based on the minimum guaranteed performance of the engine at different altitudes and temperatures, as well as the engine installation losses in hovering, level flight and climbing conditions. The minimum guaranteed performance of the engine represents the minimum power that can be output during the entire life cycle of the engine, and the available power of the helicopter at different altitudes and temperatures in hovering, level flight and climbing conditions is obtained.

6. The method for determining helicopter flight performance through test flight data according to claim 5, characterized in that: Engine installation loss = (engine bench power - engine measured power) / engine bench power.

7. The method for determining helicopter flight performance through test flight data according to claim 5, characterized in that: Helicopter available power = engine minimum guaranteed performance * (1-engine installation loss).

8. The method for determining helicopter flight performance through test flight data according to claim 5, characterized in that: S5 is as follows: Determine the helicopter flight performance: The required power and available power for hovering, level flight and climbing states determined above can be used to determine the helicopter flight performance by balancing the two. The helicopter flight performance includes the weight, speed and climb rate that the helicopter can achieve at a specific altitude and temperature.

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