Summary of the invention
The invention of this aircraft topological design, adopts high lift-drag ratio positive camber aerofoil profile, and does not utilize horizontal tail or canard etc. to bring the means that reduce full machine 1ift-drag ratio, realizes the trim of wing zero lift moment, gives full play to positive camber aerofoil profile high lift-drag ratio characteristic.In order to realize the trim of wing zero lift moment, and do not cause full machine 1ift-drag ratio to decline.The layout that adopts gravity allocation to locate under wing focus to produce large 1ift-drag ratio and nose-up pitching moment, makes full facility have Longitudinal static stability simultaneously.Can improve the 1ift-drag ratio of aircraft, can make again full facility have static stability.
According to an aspect of the present invention, provide a kind of high lift-drag ratio fixed wing aircraft, it is characterized in that comprising:
There is the wing of high aspect ratio positive camber, for lift is provided, thereby provide full machine lift,
Be positioned at the fuselage under the focus of wing,
Wing support beam, for connecting described fuselage and wing,
Be arranged on the driving engine on fuselage, for thrust is provided.
According to another aspect of the present invention, provide a kind of implementation method of high lift-drag ratio of fixed wing aircraft, it is characterized in that comprising:
Provide lift with the wing with high aspect ratio positive camber, thereby full machine lift be provided,
Fuselage is arranged under the focus of wing,
Connect described fuselage and wing with wing support beam,
Provide thrust with the driving engine being arranged on fuselage.
Detailed description of the invention
Adopt the airplane design of independent positive camber aerofoil profile, as being in airfoil lift, act on zero lift moment on wing non-vanishing at 1 o'clock, this moment will make full machine produce nose-down pitching moment.Need the take measures zero lift moment of trim wing.Usual way comprises horizontal tail, canard etc., specifically sees force analysis Fig. 1.
Fig. 1 (a) is for adopting tailplane Calculate Ways, and O point is full machine center of gravity.Positive camber wing (1) zero lift moment is bowed full machine.The lift (Lw) of horizontal tail is downwards, and makes full machine zero lift moment coefficient for just, is nose-up pitching moment, realizes full machine trim.But the method causes full machine loss of lift.
Fig. 1 (b) is for adopting canard Calculate Ways, and O point is full machine center of gravity.Positive camber wing (1) zero lift moment is bowed full machine.The lift (Ly) of canard is for upwards, and makes full machine zero lift moment coefficient for just, is nose-up pitching moment, realizes full machine trim.But the method causes full machine resistance to increase.
And the present invention adopts the trim measure of not losing full machine 1ift-drag ratio.According to one embodiment of present invention, under being disposed to wing focus, full mechanical coke point locates, as shown in Figure 2.
In Fig. 2 (a), in the distance under incoming flow (V0) effect, the stressed and trim situation of full machine is: full machine lift (L) and gravity (G) balance, thrust (T) and air resistance (D) balance; The moment of resistance (D) and center of gravity (O) is nose-up pitching moment, the zero lift moment (M0) that this moment can trim positive camber wing (1), thus realize the moment trim of full machine.And do not lose the 1ift-drag ratio of full machine.The true angle of incidence (a) is the corresponding angle of attack of wing maximum lift-drag ratio for this reason time.
In Fig. 2 (b), aircraft horizontal flight, run into become d a beam to disturb incoming flow (V1) during with horizontal surface, stressed and the trim situation of full machine is: aircraft is d a with respect to the angle of attack that disturbs incoming flow (V1), lift (d L) direction and interference incoming flow (V1) direction are vertically upward, resistance (d D) direction is identical with interference incoming flow (V1) direction, and other power do not change; Resistance (d D) horizontal component and lift (d L) horizontal component and thrust-balancing.Compared with Fig. 2 (a) resistance (D) lift (L), resistance (d D) counterweight mental and physical efforts arm reduces, lift (dL) counterweight mental and physical efforts arm increases, two power are negative with the moment that full machine center of gravity (O) forms, be nose-down pitching moment, (d a) changes, when making full facility have static stability to reduce the increase of the full machine angle of attack.
In Fig. 2 (c), aircraft horizontal flight, run into become d a ' beam to disturb incoming flow (V2) during with horizontal surface, stressed and the trim situation of full machine is: aircraft is d a ' with respect to the angle of attack that disturbs incoming flow (V2), the lift arm of force (dL ') direction with disturb incoming flow (V2) direction vertically upward,, resistance (d D ') direction is identical with interference incoming flow (V1) direction, and other power do not change; Resistance (d D ') horizontal component and lift (d L ') horizontal component and thrust-balancing.。Compared with Fig. 2 (a) resistance (D) lift (L), resistance (d D ') counterweight mental and physical efforts arm reduces, the lift arm of force (d L ') increases center of gravity, the moment that two power and full machine center of gravity (O) form is for just, be nose-up pitching moment, reduce (the d a ') that reduce the full machine angle of attack changes, and makes full facility have static stability.
In sum, the present invention can give full play to positive camber aerofoil profile high lift-drag ratio advantage, improves the 1ift-drag ratio of full machine.
Fig. 3 has shown high lift-drag ratio fixed wing aircraft according to an embodiment of the invention, and it adopts high aspect ratio positive camber wing (1), and fuselage (4) is positioned under wing focus, is connected with wing (1) by wing support beam (2).Realize the sliding landing of running by tricycle landing gear (8,9,10), the interior visual field of driving compartment (6) is good.
As shown in Figure 3, full machine center of gravity is positioned at O point, and wing focus is positioned at O ' point.When aircraft is in the time that airless interference level flies, its full machine lift (L) and gravity (G) balance, driving engine (5) thrust (T) and full machine resistance (D) balance, thus reach full machine power balance; Full machine lift (L), gravity (G) thrust (T) is passed through center of gravity, therefore be zero with respect to center of gravity O pitching moment, and full machine resistance (D) is not by center of gravity O, it is H with respect to the center of gravity O arm of force, with respect to the moment of center of gravity O just in time with wing zero lift moment (M0) trim, thereby realize force balance and the moment balance of full machine.In figure, wing support beam (2) specific design height has determined arm of force H, is determined by the zero lift moment of selected positive camber wing (1).The zero lift moment of resistance under cruising condition (D) and arm of force H-vector moment balance positive camber wing (1).In the time that wing zero lift moment is large, the selected corresponding increase of H value.
The flight control of aircraft realizes by a pair of aileron (2,3) on wing, and aileron (2,3) is in order to the control of Aircraft Lateral side direction.And longitudinal pitch control subsystem of aircraft, by the change of control engine (5) thrust size, realizes the lifting of aircraft.Engine thrust increases, and realizes aircraft altitude and climbs; Engine thrust reduces, and the height of realizing aircraft reduces.
Advantage of the present invention comprises:
Compared with prior art, there is obvious technical advantage in the present invention:
Positive camber aerofoil profile 1ift-drag ratio is large, but in existing airplane design, can not give full play to positive camber aerofoil profile high lift-drag ratio advantage.Reason is mainly: the technical measures of zero liter of pitching moment of trim have reduced the 1ift-drag ratio of full machine.
The present invention is directed to above weakness, proposed a kind of brand-new aircraft layout.By force analysis, can meet power and moment trim requirement, prove that it is effective, and can give full play to the high lift-drag ratio characteristic of positive camber aerofoil profile wing, thereby reach the object that improves aircraft 1ift-drag ratio.