A method for determining helicopter flight performance from flight test data

Abstract

The present application belongs to the technical field of helicopter design, and particularly relates to a method for determining the flight performance of a helicopter through flight test data. The method comprises: obtaining the hovering required power according to the hovering flight test data; determining the level flight required power according to the variable-height level flight test data, wherein the helicopter equivalent weight is kept unchanged by adjusting the flight height during the variable-height level flight; determining the climb efficiency and the climb required power according to the sawtooth climb flight test data; determining the engine installation loss according to the hovering, level flight and climb flight test data, so as to determine the available power of the helicopter; and determining the flight performance according to the required power and the available power of the helicopter in the hovering, level flight and climb states.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopter design, and particularly relates to a method for determining helicopter flight performance through flight test data. BACKGROUND

[0002] In the airworthiness verification process of a civil helicopter, regulations require that the helicopter flight performance be given, and the helicopter flight performance is obtained by balancing the required power and the available power. The required power of the helicopter is the power consumed to maintain the hovering, flat flying and climbing state. The available power of the helicopter is the minimum output power of the engine after considering the installation loss. In addition, in the flight test process, as the fuel is consumed, the weight of the helicopter gradually decreases, deviating from the target weight, resulting in the need to eliminate the influence of weight error in the flight test processing. The traditional flight test data processing method generally uses performance calculation software to correct the weight error, but since the performance calculation software introduces uncertain error, it does not meet the requirements of the airworthiness verification of the civil helicopter. SUMMARY

[0003] To solve the above problems, the application provides a method for determining helicopter flight performance through flight test data, which determines the required power and available power of the helicopter in different states through hovering, flat flying and climbing flight test data, directly determines the helicopter flight performance according to the flight test data, and meets the airworthiness verification requirements.

[0004] To achieve the above purpose, the application adopts the following technical solutions.

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

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

[0007] S2, determining the flat flying required power according to the variable height flat flying flight test data, and keeping the helicopter conversion weight unchanged by adjusting the flight height during the variable height flat flying;

[0008] S3, determining the climbing efficiency and the climbing required power according to the sawtooth climbing flight test data;

[0009] S4, determining the engine installation loss according to the hovering, flat flying and climbing flight test data, so as to determine the available power of the helicopter;

[0010] S5, determining the flight performance according to the required power and the available power of the helicopter in the hovering, flat flying and climbing states.

[0011] Further, S1 is specifically:

[0012] The conversion weight and conversion power relationship curve is determined through the hovering flight data of the plain, plateau and high-cold, and the hovering required power at any height, temperature and weight can be obtained through interpolation;

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

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

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

[0016] Further, S2 is specifically:

[0017] S21, set the target height and initial target weight of the helicopter level flight;

[0018] S22, obtain the variable height flight data for keeping the helicopter conversion weight unchanged, and obtain the relationship curve of the level flight speed and required power;

[0019] S23, at the target height, change the target weight, and repeat S22 to obtain the relationship curve of the level flight speed and required power at different target weights at the target height;

[0020] S23, change the target height of the helicopter level flight, and repeat S22-S23 at the target height of the helicopter level flight and the initial target weight to obtain the relationship curve of the level flight speed and required power at different target heights and target weights;

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

[0022] Further, S3 is specifically:

[0023] Determine the climb required power: determine the climb efficiency through the sawtooth climb flight data at different heights and weights;

[0024] The climb efficiency calculation method is:

[0025] Climb efficiency = (helicopter measured weight x 9.8 x measured climb rate) / (helicopter measured power - level flight required power)

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

[0027] The climb efficiency data is counted, the climb efficiency curve varying with the speed is determined, the power required for climb at any height, temperature, weight, speed and climb rate is obtained by interpolation in combination with the power required for level flight determined above.

[0028] Further, S4 is specifically:

[0029] The engine bench power corresponding to the height and temperature is obtained through the height, temperature and engine control parameters in hovering, level flight and climb flight test data, and the engine bench performance; the engine bench performance represents the relationship between the engine control parameters and the engine output power when the engine is shipped;

[0030] The engine installation loss in the hovering, level flight and climb state is determined by comparing the engine bench power and the engine measured power.

[0031] The helicopter available power is determined according to the engine minimum guarantee performance at different heights and temperatures, and the engine installation loss in the hovering, level flight and climb state; the engine minimum guarantee performance represents the minimum power that can be output by the engine in the whole life cycle of the engine, and the helicopter available power at different heights and temperatures in the hovering, level flight and climb state is obtained.

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

[0033] Further, the helicopter available power = engine minimum guarantee performance*(1-engine installation loss).

[0034] Further, S5 is specifically:

[0035] The helicopter flight performance is determined: the helicopter flight performance is determined by balancing the required power and the available power in the hovering, level flight and climb state determined above, and the helicopter flight performance includes the weight, speed and climb rate that can be achieved by the helicopter at a specific height and temperature.

[0036] The method for determining the helicopter performance through the flight test data provided by the technical scheme of the present application determines the hovering, level flight and climbing required power in any state through interpolation calculation according to the hovering, level flight and climbing flight test data under the specific height, temperature and weight; determines the available power in the hovering, level flight and climbing states according to the engine bench performance, and can determine the helicopter flight performance through the required power and available power trim calculation. In the above data processing process, the weight error caused by the fuel consumption in the flight test process does not need to be corrected by using the performance calculation software, and more accurate flight performance calculation results can be obtained to meet the requirements of airworthiness verification. DETAILED DESCRIPTION

[0037] The technical scheme of the present application will be described in detail below.

[0038] The method for determining the helicopter performance through the flight test data provided by the embodiment of the present application comprises:

[0039] 1) obtaining the hovering required power according to the hovering flight test data;

[0040] The conversion weight and conversion power relationship curve is determined through the hovering flight test data of the plain, plateau and high-cold, and the hovering required power under any height, temperature and weight can be obtained through interpolation;

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

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

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

[0044] 2) determining the level flight required power according to the variable height level flight test data, in the variable height level flight process, the helicopter conversion weight is kept unchanged by adjusting the flight height;

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

[0046] S22, obtaining the variable height flight test data for keeping the helicopter conversion weight unchanged, and obtaining the relationship curve of the level flight speed and required power;

[0047] S23, change the target weight at the target height, repeat S22-S23 to obtain the relationship curve of the flight speed and the required power at different target heights and target weights;

[0048] S23, change the target height of the helicopter flight, repeat S22-S23 to obtain the relationship curve of the flight speed and the required power at different target heights and target weights;

[0049] S24, the flight required power at any height, temperature, weight, and speed can be obtained by interpolation;

[0050] Taking a type of dual-engine civil helicopter as an example, the variable-height flight test state is shown in the following table, covering small weight to large weight, low height to high height. The flight required power curves of the following states are determined according to the test data, and the flight required power at any height, temperature, weight, and speed can be obtained by interpolation;

[0051]

[0052] 3) Determine the climb efficiency according to the sawtooth climb test data, and further determine the climb required power;

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

[0054] The climb efficiency calculation method is:

[0055] Climb efficiency = (measured weight of the helicopter × 9.8 × measured climb rate) / (measured power of the helicopter - flight required power)

[0056] Wherein the flight required power is calculated according to the above flight required power method;

[0057] Statistical climb efficiency data, determine the climb efficiency curve with speed change, combined with the above determined flight required power, through interpolation, the climb required power at any height, temperature, weight, speed and climb rate can be obtained;

[0058] 4) Determine the engine installation loss according to the hovering, flight, and climb test data, and thus determine the available power of the helicopter;

[0059] Through the height, temperature and engine control parameters in the hovering, flight, and climb test data, and the engine bench performance, the engine bench power corresponding to the height and temperature is obtained; the engine bench performance represents the relationship between the engine control parameters and the engine output power when the engine is shipped;

[0060] The engine bench power is compared with the measured engine power to determine the engine installation loss in the hovering, level flight and climbing states.

[0061] The engine installation loss=(engine bench power-measured engine power) / engine bench power.

[0062] According to the engine minimum guaranteed performance at different altitudes and temperatures and the engine installation loss in the hovering, level flight and climbing states, the available power of the helicopter is determined. The helicopter available power=engine minimum guaranteed performance*(1-engine installation loss), and the helicopter available power at different altitudes and temperatures in the hovering, level flight and climbing states is obtained.

[0063] 5) According to the required power and available power of the helicopter in different states, the flight performance is determined.

[0064] The flight performance of the helicopter is determined: the required power and available power in the hovering, level flight and climbing states determined above are balanced to determine the flight performance of the helicopter. The flight performance of the helicopter includes the weight, speed and climbing rate that can be achieved by the helicopter at a specific altitude and temperature.

[0065] The method for determining the helicopter performance through flight test data provided by the technical scheme of the application determines the required power in the hovering, level flight and climbing states in any state through interpolation calculation according to the hovering, level flight and climbing flight test data at a specific altitude, temperature and weight. The available power in the hovering, level flight and climbing states is determined according to the engine bench performance, and the flight performance of the helicopter is determined by balancing the required power and available power. In the above data processing process, the weight error caused by fuel consumption in the flight test does not need to be corrected by using performance calculation software, and more accurate flight performance calculation results can be obtained to meet the requirements of airworthiness verification.

Claims

1. A method of determining the flight performance of a helicopter from flight test data, characterised in that, The method comprises: S1, obtaining hover required power according to hover flight test data; S1 is specifically: Determine the conversion weight and conversion power relationship curve through the hover flight test data of the plain, plateau and high-cold, and the hover required power at any height, temperature and weight can be obtained through interpolation; Helicopter scale weight = helicopter measured weight x δ 目标 / δ x ((N R额定 ) / N R )^2; Helicopter converted power = helicopter measured power x δ 目标 / δ x ((N R额定 ) / N R )^3; δ is the measured atmospheric density ratio, δ 目标 N is the standard atmospheric density ratio, N R N is the measured rotor speed, N R额定 N is the rated rotor speed; S2, determine the level flight required power according to the variable height flight test data, and keep the helicopter conversion weight unchanged by adjusting the flight height during the variable height flight; S2 is specifically: S21, set the target height and initial target weight of the helicopter level flight; S22, obtain the variable height flight test data for keeping the helicopter conversion weight unchanged, and obtain the relationship curve of the level flight speed and required power; S23, change the target weight at the target height, repeat S22 to obtain the relationship curve of the level flight speed and required power at the target height and different target weights; S23, change the target height of the helicopter level flight, repeat S22-S23 at the target height of the helicopter level flight and the initial target weight to obtain the relationship curve of the level flight speed and required power at different target heights and target weights; S24, the level flight required power at any height, temperature, weight and speed can be obtained through interpolation; S3, determine the climb efficiency and climb required power according to the sawtooth climb flight test data; S3 is specifically: Determine the climb required power: determine the climb efficiency through the sawtooth climb flight test data at different heights and weights; The climb efficiency calculation method is: Climb efficiency=(measured weight of the helicopter×9.8×measured climb rate) / (measured power of the helicopter-level flight required power) Wherein the level flight required power is calculated according to S2; Statistical climb efficiency data, determine the climb efficiency curve with speed change, combined with the above determined level flight required power, the climb required power at any height, temperature, weight, speed and climb rate can be obtained through interpolation; S4, determine the engine installation loss according to the hover, level flight and climb flight test data, and determine the helicopter available power; S5, determine the flight performance according to the helicopter required power and available power in hover, level flight and climb state.

2. A method of determining the flight performance of a helicopter from flight test data according to claim 1, characterised in that, S4 is specifically: Obtain the engine bench power corresponding to the height and temperature through the height, temperature and engine control parameters in the hover, level flight and climb flight test data, and the engine bench performance; the engine bench performance represents the relationship between the engine control parameters and the engine output power when the engine is shipped; Compare the engine bench power with the measured engine power to determine the engine installation loss in hover, level flight and climb state; Determine the helicopter available power according to the engine minimum guarantee performance at different heights and temperatures, and the engine installation loss in hover, level flight and climb state; the engine minimum guarantee performance represents the minimum power that can be output by the engine in the whole life cycle of the engine, and the helicopter available power at different heights and temperatures in hover, level flight and climb state is obtained.

3. The method for determining the flight performance of a helicopter through flight test data according to claim 2, characterized in that, Engine installation loss = (engine bench power - engine measured power) / engine bench power.

4. The method of claim 2, wherein the flight performance of the helicopter is determined by balancing the required power and the available power. Helicopter available power = engine minimum guaranteed performance * (1 - engine installation loss).

5. A method of determining the flight performance of a helicopter from flight test data according to claim 2, wherein, S5 is specifically: Determine the flight performance of the helicopter: through the required power and the available power of the hovering, the level flight and the climbing state determined above, the flight performance of the helicopter can be determined by balancing, and the flight performance of the helicopter includes the weight, the speed and the climbing rate that the helicopter can realize flight in a specific height and temperature state.

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