# The method of determining the position of the center of mass of the helicopter

The invention relates to the field of aviation technology and concerns a method for determining the position of the center of mass of the helicopter with bearing propellers mounted on the fuselage at different heights. Consistently measure the amplitude of the fuselage of the helicopter in hovering mode without unbalance loads, and with alternately mounted on each mounting screw unbalance loads, then a certain mathematical dependencies determine the position of the center of mass of the helicopter. The invention improves the accuracy of determining the position of the center of mass of the helicopter, namely to determine the vertical distance from the bottom of the rotor to the center of mass of the helicopter. 1 Il.

The invention relates to the field of aviation technology and concerns a method for determining the position of the center of mass of the helicopter.

There is a method of determining the position of the center of mass of the helicopter, which consists in the excitation of the vibrational frequency of rotation of the bearing screws alternately installed on the upper and lower screws on one unbalance the load, the measurements of the fluctuations in the hovering mode and determining the position of the center of mass of the island is the center of mass of the helicopter is determined only for a helicopter with balanced bearing screws. However, by helicopter and after balancing there are imbalances bearing screws. The presence of existing imbalances main rotors of the helicopter is not possible to obtain accurate position of the center of mass of the helicopter.

The task of the claimed technical solution is to determine the position of the center of mass of the helicopter at the current imbalances bearing screws and implementing technical effect of improving the reliability of determination of the position of the center of mass of the helicopter.

The essential features of the proposed method of determining the position of the center of mass of the helicopter, in common with the prototype, the following: initiate design variations with frequency of rotation of the bearing screws alternately installed on the upper and lower screws on one disbalance the load, measure the parameters of fluctuations in the hovering mode and the measurement result is judged on the position of the center of mass of the helicopter.

Signs, other than the prototype are: on each mounting screw unbalance load alternately establish the second time in a diametrically opposite position with respect to the axis of rotation of the upper and lower bearing screws, measure the amplitude of the angular oscillation of the helicopter.

Sr="0">nwith unbalance load in the first position respectively on the upper and lower bearing screws

B;nwith unbalance load in the second position diametrically opposite direction respectively on the upper and lower bearing screws

and the distance h from the bottom screw to the center of mass of the helicopter is determined by mathematical expressions

where mB, mHthe mass unbalance of the load respectively, the upper and lower bearing screws;

rB, rH- the distance from the axis of rotation of the screw to the unbalance of the load respectively, the upper and lower bearing screws;

c - the distance between the upper and lower bearing screws.

The set of features of the claimed invention is necessary and sufficient to ensure technical result.

The technical result is to increase the reliability of determining the position of the center of mass of the helicopter is realized with the implementation of the essential features of the claimed invention, a causal relationship between them follows from the results of pH the side view of the helicopter.

On the helicopter fuselage 1 with center of mass 2 fixed lower 3 and upper 4 bearing screws. The axis of rotation of the screws 5. The drawing shows a coaxial helicopter, so the axis of the lower and upper screws are the same. The longitudinal helicopter axis of the lower and upper screws spaced along the length of the fuselage and not the same. For the proposed method of determining the position of the center of mass of the helicopter with two carrier screws attached to the fuselage at different heights, their placement along the length of the fuselage doesn't matter. The drawing shows the OXY coordinate system associated with the helicopter with the origin at the center of mass 2 and the axis of OW parallel to the axis 5. The angular displacement of the helicopter 6 markedt. The axis of sensitivity of the vibration sensor 7, 8, 9 lie in the plane HOU, which is the center of mass 2 and the axis of sensitivity of the shock sensor 8 passes through the center of mass 2. The amplitude of the vertical vibrations of the helicopter by the vibration sensor 7 and 9 denote respectively the1and I2a by the vibration sensor 8 - y0. The distance from the center of mass 2 to the bottom of the screw 3 denoted by h, the distance between the screws 3 and 4 C. the distance from the vibration sensor 7 to the center of mass 2 marked1; from the vibration sensor 9 Dawes upper rotor with mass mBand the distance rBto the axis of rotation of the set screw 5 in the first position 10 (+mBrBand in the second position 11 (-mBrBwith a diametrically opposite direction relative to the axis of rotation 5. Unbalance load of the lower rotor with mass mHand the distance rHto the axis of rotation of the set screw 5 in the first position 12 (+mHrHand in the second position 13 (-mHrHwith a diametrically opposite direction relative to the axis of rotation of the screw 5.

The method of determining the position of the center of mass of the helicopter is implemented as follows. The vibration sensors 7, 8, 9 measure the amplitude of the fuselage 1 helicopter at the frequency of rotation of the main rotors 3 and 4 when flying a helicopter in hovering mode without unbalance of loads on the supporting screws. Then, interrupting the flight of the helicopter, install one screw (on the top) unbalance load of mass mBin the first position 10 (+mBrB) and measure the amplitude of the oscillations of helicopter in hovering mode. Interrupted flight, remove unbalance load with position 10, install it in the second position 11 (-mBrBwith a diametrically opposite direction relative to the axis of rotation 5 and measure the amplitudes of the I 11. Mounted on the other screw (on the bottom) unbalance load of mass mHin the first position 12 (+mBrH) and measure the amplitude of the oscillations of helicopter in hovering mode. Interrupted flight, remove unbalance load from position 12, install it in the second position 13 (-mHrHwith a diametrically opposite direction relative to the axis of rotation 5 and measure the amplitude of the oscillations of helicopter in hovering mode. According to the measurement results determined by mathematical expressions (14), (15) the distance from the bottom screw to the center of mass of the helicopter. Thus the amplitude of the angular oscillation of the helicopter calculated by mathematical formula (20).

The possibility of implementing a technical solution follows from the description of the sequence of its implementation and follows from the solution of the differential equation of angular oscillations of helicopter

where J is the moment of inertia of the helicopter;

SB, SHexisting imbalance, respectively, the upper and lower bearing screws;

B,Hthe phase between the current imbalance and the imbalance in the first position, respectively, the upper and lower bearing VI is the I harmonic and proceed with the amplitude of the angular oscillation:

Swithout unbalance loads on bearing screws (17);

B,Hwith unbalance load in the first position respectively on the upper and lower bearing screws..... (18);

-B,-Hwith unbalance load in the second position diametrically opposite direction respectively on the upper and lower bearing screws....(19).

The solution of equation (16) for cases(17), (18), (19) the resulting mathematical expression (14), (15) to calculate the distance from the bottom screw to the center of mass of the helicopter. In turn, the amplitude of the angular oscillation of the helicopter is associated with its linear amplitudes of the oscillations as follows:

where j=S;; -; n; -N.

As a result of implementation of the proposed technical solution is to determine the position of the center of mass of the helicopter.

Claims

The method of determining the position of the center of mass of the helicopter, mainly helicopter with bearing screws attached to the fuselage at different heights, which consists in vozbuzhdenii one unbalance the load, the measurements of the fluctuations in the hovering mode and determining the position of the center of mass of the helicopter in mathematical expression, wherein each mounting screw unbalance load alternately establish the second time in a diametrically opposite position with respect to the axis of rotation of the upper and lower bearing screws, measure the amplitude of the angular oscillation of the helicopter:Swithout unbalance loads on bearing screws;B,Hwith unbalance load in the first position respectively on the upper and lower bearing screws;-B,-H- c unbalance load in the second position diametrically opposite direction respectively on the upper and lower bearing screws, and the distance h from the bottom screw to the center of mass of the helicopter is determined by mathematical expressions

where min, mnthe mass unbalance of the load respectively, the upper and lower bearing screws;

rin; rn- the distance from the axis of rotation of the screw to the unbalance of the load respectively werhner the

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