RU2594321C1 - Aerodynamic profile of bearing surface of aircraft - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: profile includes upper convex AVMS and lower ANEDC circuits connected to front and rear edges, coordinates of which are defined relative to AC profile chord. Concave part NED of lower circuit follows the curvature of AVM upper contour. Curve of lower circuit has front N and rear D inflection points. Front point has rounding radius R. Point of maximum curvature B in upper circuit is located on one vertical line with the upper point E of lower circuit maximum curvature. Top contour on side of rear edge has concavity M to make MS profile tail.

EFFECT: higher lift of lifting propeller blade.

1 cl, 3 dwg

Description

The invention relates to aircraft manufacturing, namely to aerodynamics, and can be used to create profiles of elastic retractable rotor blades of rotor rotors for vertical take-off and landing aircraft, rigid rotor rotor blades of helicopters, airplane wings, aircraft propellers, rescue systems and soft landing of space objects.

Known rotor with removable (wound on drums) elastic blades having a variable profile along the length of the blade, while the butt part, two turns of the winding, has a flat profile, and then to the end of the blade has a biconvex profile (US Patent No. 3637168, IPC B64C 27/46, 01.25.1972).

The aerodynamic profiles of the bearing surfaces of aircraft are known (Kashafutdinov SG, Lushin B.C. Atlas of aerodynamic characteristics of wing profiles. - Novosibirsk: Publishing House Sib-NIA, 1994).

Known profiles NACA-23009 and NACA-23012, used in the production of rotor blades of most modern helicopters (Helicopters of the World. Edited by Lebed V.G. Publishing House of the Editorial Board of the magazine "Boomerang" with the participation of the company "April", 1994 .).

Elastic retractable blades, with the above profiles, cannot be folded (wound) onto the drums without distortions and possible breakages of the edges of the blades due to the impossibility of two convex planes overlapping each other.

The second common drawback that combines the above profiles is that most of the lifting force of the bearing surface is formed by creating a vacuum along the upper surface contour and a smaller part due to pressure on the lower contour from the incoming flow.

A known wing profile of the aircraft (Patent RU No. 2461492, IPC В64С 3/14, В64С 27/32, В64С 11/18, 09/20/2012) containing sharp front and rear edges, as well as upper and lower contours, with the lower contour made rectilinear from the leading to the trailing edge, forming a chord of the profile, and the upper contour has a straight portion that is parallel to the longitudinal axis of the aircraft and connected to the trailing edge of the lower contour of a smooth curve.

For a wing with such a profile, the lifting force is formed by the interaction of the incident flow only with the lower contour due to the installation angle of the lower contour. The pressure on the upper circuit is almost equal to the pressure of unperturbed air at altitude. As a result, the total lifting force of a wing with such a profile is more than twice the lifting force of a wing of a similar size with a profile of a biconvex classical shape. But an elastic rotor blade with such a profile cannot be rolled up and wound onto a drum without distortions and damage to the edges of the blade.

The first objective of the invention is to increase the efficiency of formation of the lifting force of the blades and, in general, increase the thrust of the rotor. The second task is to create a profile that allows the elastic blade to fold (wrap around the drum) without distortions and damage to the edges of the blade.

The third task is to develop a profile of the bearing aerodynamic surface, allowing the elastic blade in the folded position to have a smaller drum diameter and, therefore, improve the compactness of the entire rotor with the blades removed.

The well-known aerodynamic profile of the supporting element of the aircraft NACA-23009, which is the closest analogue to the claimed profile, is taken as a prototype.

The NACA-23009 profile is biconvex asymmetrical and represents the main profile for the manufacture of rigid rotor blades of the majority of existing helicopters.

The profile performs its function quite effectively - it creates the lifting force of the rigid blade of the helicopter, but requires refinement and changing its shape in the manufacture of an elastic, rollable onto the drum blade with a simultaneous even greater increase in the lifting force of the blade.

The technical result, the solution of which the present invention is directed, is to create a compact device - a rotor with elastic blades removed (wound on a drum) without distortions and edge damage for vertical take-off and landing aircraft with a simultaneous increase in the lifting force of the rotor blades during its operation.

The invention is illustrated by drawings, which depict the following.

In FIG. 1 presents a profile according to the invention, where:

AVMSK - a profile taken as a prototype, all points of which are given by coordinates relative to the profile chord.

AVMS - the upper profile contour.

AKS - bottom profile profile.

AU - profile chord.

In - the most remote point of the upper contour from the profile chord.

BE is the height of point B from the AC chord.

ABMCDEN - profile according to the invention.

NED is the concave part of the lower profile contour having the same curvature with the upper AVM contour. In this case, the lower concave contour does not intersect the AC chord, and the upper contour from the trailing edge side has a concavity downward - point M, forming the MS profile shank.

N is the front inflection point of the lower profile contour having a radius of curvature R.

D is the rear inflection point of the lower profile contour.

The method for forming the ABMCDEN profile according to the proposed invention has several options, for example, a vertical downward copy of the A′EM′C′K ′ profile of the prototype by the distance BE of the most distant point B in the curve of the upper contour from the chord of the AC profile, i.e. BE = EE ′, and the superposition of the upper contour A′EM′C of the shifted profile on the lower contour of the ACS of the upper profile with the formation of the concave part NED of the lower contour, the front N and the back D inflection points.

In FIG. 2 shows a general view of a folding elastic blade with a profile according to the invention.

1 - drum reel.

2 - butt flat part of the blade, having a length of one revolution of the drum.

2 ′ is the profile of the butt part of the blade.

3 - the first inclined transition plano-convex profile.

4 - the intermediate part of the blade, having a length of one revolution of the drum, with a plano-convex profile.

4 ′ is the profile of the intermediate part of the blade having the upper contour of the same curvature as the upper contour of the main working part of the blade.

5 - the first converted profile of the main working part of the blade.

5 ′ - profile of the main working part of the blade.

6 - the main working part of the blade with a converted profile.

7 - line shank profiles of the main working part of the blade.

8 - centrifugal load.

9 - stabilizer.

10 - steering surface.

11 - hinge joints.

In FIG. 3 shows a half-section of a drum coil with a rolled elastic blade.

The proposed aerodynamic profile of the bearing surface of the aircraft operates as follows.

When the blade is folded, it has a flat profile 2 ′ of the butt part 2 with a length of one first revolution tightly without distortions and damage to the edges of the blade rests on the main part of the reel 1 of the drum.

In the second revolution, the blade also fits tightly with the lower flat surface of the convex profile 4 ′ of the intermediate part 4 of the blade on the flat surface of the previous revolution of the blade with a flat profile.

At the third revolution and further folding, the blade with the lower concave surface NED fits tightly without distortions and damage to the blade edges on the upper surface of the AVM of the transformed profile of the main working part of the blade due to their identical curvature.

Due to the decrease in the relative thickness of the blade, its tight fit during folding, the diameter of the drum decreases, which means that the compactness of the entire rotor with the blades removed is improved.

When a carrier element with the specified profile moves in the air flow, the total lifting force arises in part due to the rarefaction of the pressure in the jet flowing around the convex profile of the upper contour of the AVM bearing surface, and the majority of the lifting force arises due to an increase in the air flow pressure due to its braking and shock pressure the concave part of the lower contour of the NED profile, with a shift in the direction from the nose of the profile to its middle part of the point of application of the total lifting force from the lower contour, due to and then a diving moment arises, which is balanced by the cabriding moment from the action of the airflow flowing around the upper contour of the MC profile shank.

The application of the proposed profile allows to improve the compactness of the rotor with the retracted (wound on the drum) without distortions and edge damage elastic blades for aircraft of vertical take-off and landing with a simultaneous increase in the lifting force of the rotor blades during its operation.

Claims (1)

The aerodynamic profile of the bearing surface of the aircraft, containing the upper and lower contours formed by convex curves and their intersection points with the given coordinates relative to the chord of the profile, characterized in that part of the lower contour is made concave, repeats the curvature of the upper contour, does not intersect the chord and the lower contour curve has front and rear inflection points, and the front point has a certain radius of curvature, while the point of maximum curvature of the upper contour is located on one in verticals with the upper point of maximum curvature of the lower contour and the upper contour from the trailing edge side have a concavity downward, forming a profile shank.

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