DE2730032A1 - AIRPLANE CONFIGURATION - Google Patents

Description

7722-24 X Bremen, d. July 1, 1977

United Aviation Technology Herke-Fokker Company with limited liability

Aircraft configuration

The invention relates to an aircraft configuration, in particular for combat aircraft operating in the sub-, trans- and supersonic area

The configurations of modern combat aircraft are determined by the Line requirements or the missions that these aircraft perform have to meet the design of the wing with a certain lift, Resistance and torque behavior are essential here Means for solving the task at hand. As an alternative, there are basically two types of wing opposite, on the one hand the delta wing, characterized by a small spread

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and a large leading edge sweep and the trapezoidal wing, which is characterized by a relatively large extension and a less pronounced leading edge sweep. Here, the leading edge ^{arrowhead is to} be understood as the angle / • which is formed from the leading edge of the wing and a line parallel to the transverse axis of the aircraft in the XY plane. The aspect ratio or aspect ratio is understood to be the quotient of the square of the wingspan to the wing area j \ «· b / F. To further differentiate between these two wing types, trapezoid and delta, the tapering must be introduced, which results from the ratio of sweeter to inner wing depth λ - l _a / I ₁ . In the case of the theoretical delta wing, this taper is equal to zero, whereas in the case of the trapezoidal wing it assumes finite values. Trapezoidal and delta wings differ in addition to these and other features through a different flow in the strongly inclined wing, so the trapezoidal wing allows only relatively small angles of attack until the flow breaks, while the delta wing allows larger angles of attack due to a controlled flow detachment on its strongly swept leading edge allows a stabilized vortex flow. In order to extend this advantage of the delta wing to the trapezoidal wing, a small delta wing, a so-called strake, has been connected in front of the trapezoidal wing with a low leading edge sweep. This strake generates its own stable vortex syotem in the area of large angles of attack, which overlaps the flow system of the trapezoidal wing and thus contributes to improved lift behavior, among other things. Such wing configurations, characterized by the combination of a trapezoidal wing with a strake, have become known from the F 16 and YF 17 combat aircraft.

The disadvantage of this known configuration is that it certain requirements, such as low structural weight, good

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High-speed flight characteristics (low drag with small lift coefficients), low gust sensitivity in low flight (small changes in the lift coefficient over the angle of attack) and good high lift properties can only solve unsatisfactorily.

The object of the invention is to provide an aircraft configuration, in particular for high-performance fighter aircraft, which avoids the mentioned tile parts of the known configurations. In particular It is the object of the invention to meet two mutually exclusive requirements (high-speed flight performance and maneuvering performance) in an aircraft.

According to the invention, the solution to this problem lies in the combination of a delta wing with a strake, but in particular in the features of claims 1-4 · By combining these two Features will not only retain the advantages of both features, i.e. the strake and the delta wing, but beyond also reinforced. In summary, this means that the combination according to the invention compared to known configurations considerable improvement of the high-lift behavior achieved A compatibility of the two Strake vertebral systems on the one hand and delta wing on the other hand was previously not considered possible, which is why the strake is only combined with a trapezoidal wing became. Contrary to this technical prejudice, eich complement however, the two vortex systems of the strake and the main or delta wing is advantageous at low angles of attack initially the leading edge vortex of the main wing is effective, while at larger angles of attack the strake vortex begins to "pull". While at such high angles of attack in the range between 20 and 30 °, the outer area of the delta wing no longer has any lift produced, prevents the strong stabilized strake vortex

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in the inner wing area that this dead water bit is calibrated from the A; '. · = · » eenbe richly spreads further inside the wing and da.c.it a change in lift brings about. The latter is bsispiolrr ^ eira the case with the delta wing without strake. Next to this sironation ceremony Advantages, which are essentially in a lift ^ c- knock down profit (improved maneuvering flight performance), lead per; the specific features of the pure delta wing (without strake) get * good high-speed flight characteristics due to a low Zero resistance and a low induced resistance br.i small C. values, low gusts sensible coil, a low r · .- · - lative wing thickness, a large wing root depth and associated with it a low wing structure weight as well as inexpensive installation options: i.ch— for trailing edge flaps.

An exemplary embodiment of the invention is shown in the drawing and is described in more detail below. Show it:

Figure 1 is a side view, Figure 2 is a plan view and Figure 3 is a perspective view of the inventive De 1 ta- strake confi gura ti on.

The essential features of the configuration according to the invention can be seen in Figure 2} the structure 1 consists of the DeltaflUgt-1 Z and the strake 3 upstream of it Esaugslirio. specified · To determine the aspect ratio ./A, the span b and the area F_ das Dsltaflü ^ ols 2 i-.v. ^ c give · This triangular area F _n is formed by the two Vtidar edges 4 and the trailing edge of the delta wing? or their dashed lines

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ORIGINAL INSPECTED

drawn extensions. The front edge 5 of the strake 3 has a significantly stronger sweep than the delta wing 2 with its front edge 4 Furthermore, the strake 3 has a lower aspect ratio than the delta wing 2. The surface of the strake F ₄ is formed by the two partial surfaces, the
in turn, the extension of the leading edge U and the intersection line 8 between strake 3 and aircraft fuselage 6 is formed by the leading edge 5 ». In addition, this aircraft configured according to the invention has two engines 9 and 10 as well as the double vertical stabilizer 11 and the horizontal stabilizer 12. Further details of the fighter aircraft according to the invention can be found in FIGS. it particularly shows the perspective representation in Figure 3 that the strake _f 3 forms an areal unit with the delta wing. 2 This exemplary embodiment represents a kite configuration - the structure 1 according to the invention, consisting of strake 3 and delta wing 2, can, however, also be used with the same advantages for other configurations.

In conclusion, it can be said that the configuration according to the invention has eliminated a technical prejudice among experts who did not consider a strake on a delta wing to be profitable because the two different vortex systems of strake and delta would influence each other unfavorably rather than favorably. In wind tunnel measurements with the model according to the invention, however, it could be demonstrated that this delta strake configuration brings considerable, surprising advantages. This primarily results in an increase in the maximum lift coefficient, combined with a higher deflectable angle of attack and an uncritical stall behavior.
Both vertebral cysteae, produced on the one hand on the leading edge 5 of the strake and on the other hand on the leading edge U of the delta wing 2,

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are therefore not only functional side by side, but also support them each other in their effect. In this respect, here from a real functional amalgamation of the features dc *; Strake and the delta wing 2 are spoken that were not expected to one Result, namely leads to an increase in the performance of this fighter aircraft * In addition, the specific properties of the delta wing and thus fully usable again.

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ORIGINAL INSPECTED

Claims (1)

7722-24 Bremen, d. July 1, 1977 claims 1. Aircraft configuration, especially for im sub, trans and fighter aircraft operating in the supersonic area, characterized in that the supporting structure (l) is combined a) a delta wing (2), i.e. a wing of small extension and large leading edge sweep and b) a so-called strake (3), i.e. a second, small triangular wing with a very small extension and a very large leading edge sweep having" 2 · Aircraft configuration according to claim 1, characterized by a delta wing (2) with a leading edge sweep of Cp ^ ä £ 50 and an aspect ratio of 3. Aircraft configuration according to claim 1 or 2, characterized by a strake (3) with a leading edge sweep of ψ _ν ί »75 °. 4. Aircraft configuration according to claim 1 or 2 or 3, characterized in that the proportion of the net area (F _8. ) Of the strakes (3) is approximately 1556 of the gross area (F _D ) of the delta wing (2). 809883/0302 QRtGINAL INSPECTED