DE102015016292B3 - Glider or motor glider with variable span - Google Patents

Abstract

Gliders, which can be used successfully with different spans in different competition classes, enjoy special popularity. In the prior art requires a large ratio between large and small span performance-reducing compromises, especially in the design of the vertical stabilizer. Therefore, no aircraft with such a ratio of more than 1.2 are known. The invention makes it possible to design gliders and motor gliders so that the aircraft can be flown either with very different spans. For this purpose, the fin is adapted to the different configurations in its size. Subclaims relate to the favorable division of the wing and the interpretation of both the flight control, the take-off masses and the fuselage wing transition. The application area is in the field of gliders and motor gliders. A larger span ratio would allow for example in an aircraft z. B. to connect the sliding performance of a large open-class aircraft with the manageability of a 18 m aircraft. The owner of an Open Class aircraft would not be forced to assemble the heaviest wing parts on every flight day.

Description

Gliders and motor gliders are aircraft that are approved in Europe predominantly according to the European building code CS 22. But there are also gliders and motor gliders in the field of light and ultralight aircraft, which are constructed according to national regulations. In the following, the term gliders also includes motor gliders.

The application is based on the object to design a glider that can be flown with very different spans, while doing in all Spannweitenkonfigurationen good rudder control and safe discharge from the spin, as well as carry in any Spannweitenkonfiguration more resistance generating rudder surface than necessary.

The object is achieved with the features of Ansprüchs. 1

Gliders are sports equipment. The Federation Aéronautique Internationale (FAI) defines different categories of competition in its Sporting Code, the main distinguishing feature of which is the maximum permissible range. (eg open class, 18m class, 15m class, 13.5m class).

• • Segelflugzeuge der 18 m-Klasse, die einen hervorragenden Kompromiß zwischen Flugleistungen und Handlichkeit darstellen.
• • Segelflugzeuge, deren Spannweite durch alternative Außenflügel auf zwei unterschiedliche Wettbewerbsklassen angepaßt werden können (1).
• • Segelflugzeuge einer Art „kleinen offenen Klasse”, die zwar in der offenen Klasse eingereiht werden müssen, zum Zwecke der Handlichkeit aber Spannweiten von nur 21 m bis 22 m aufweisen. (im Vergleich zu 28 m bis 29 m ambitionierterer Typen)

In the years since 2000, the following trends have emerged among manufacturers of gliders. Large quantities reached

• • Gliders of the 18 m class, which represent an excellent compromise between flight performance and manageability.
• • Gliders whose wingspan can be adapted to two different classes of competition by alternative outer wings ( 1 ).
• • 'small open class' type gliders, which must be classified in the open class but have a span of only 21 to 22 meters for the sake of handling. (compared to 28 m to 29 m of more ambitious types)

An extrapolation of the trends described would point in the following direction: Furthermore, the ability to start in the 18 m class continues to offer the variability of being able to compete in two competitive classes, but again to offer more wingspan in the "small open class". A corresponding aircraft would be one that can be flown with 18 m and with, for example, 26 m wingspan. The ratio of the spans would be 1.44: 1.

As the span ratio increases, it becomes increasingly difficult to optimize a span configuration without significantly sacrificing flight performance and characteristics of the other configuration. In the prior art, in the 1 and 2 span ratios of a maximum of 1.2: 1 (18 m to 15 m) are achieved. New solutions are required to enable a competitively priced competitive glider with a wide span ratio in an economical design. A first problem is the design of the tail units.

For the larger span, a larger vertical stabilizer (E) is required, which creates unnecessary profile resistance in the small span configuration and prevents balanced rudder adjustment.

The effectiveness of the tail units is described by their respective tail volume, it is the product of the base of the tail with its lever arm to fly center position. The vertical stabilizer volume is compared with the product of wing area with wing span. Roughly approximated, the fin volume at a given depth of the root rib must grow approximately quadratically with the span. The tailplane volume is compared with the product of wing area and reference wing depth. It only changes approximately linearly with the span. If the vertical and vertical stabilizer are dimensioned with an optimum size for the small span, the tail unit (F) must be extended to an acceptable extent so that the horizontal stabilizer (D) is sufficient even for the large span configuration. The additional length of the tail boom (F) plays in the resistance balance is not a significant role, since the additional piece in the wake of the fuselage floats. However, a further extension of the tail unit is precluded by various reasons: the required center of gravity, the increasing unwieldiness and the maximum length of street-legal transport trailers. Therefore, the surface of the vertical tail (E) is too small for the large span configuration.

The solution to this contradiction arises when the vertical stabilizer (E) can be increased by attaching or replacing parts as soon as the large span is assembled. For that there are different possibilities. 3 shows, as with a T-tail - here the horizontal stabilizer (D) sits on top of the fin (E) and can be dismantled - an intermediate piece (H) between the fin (E) and tailplane (D) is used. Fittings for backlash-free connection are already inevitably present due to the separation point between horizontal stabilizer (D) and vertical stabilizer (E).

A static and flattertechnisch cheaper solution shows the exploded view in 4 , Here is an extension (J) below the Tailplane (F) and the existing vertical stabilizer (E) mounted. It is integrally formed on the tail unit (F) and can be fastened, for example, with lugs (K) to the take-up of the tail wheel axis (M) in the tail unit (F). The tail wheel (G) is taken out of the tail boom (F). The lug (J) then carries even below a spur or tail wheel (G '). One or more lateral force bolts (I), for example on the nose, take over lateral loads. Preferably, the rudder (N) adjoins automatically, for example by a positive connection, such as a tongue and groove joint (L). The lower end piece (J) not only increases the extension of the vertical stabilizer (E), but also allows the end piece (J) to be rejuvenated downwards. Both increase the aerodynamic quality and effectiveness of the vertical stabilizer (E). In 6 it is shown that the ground angle only decreases as far as it is readily acceptable.

5 shows another possibility, namely the rudder (N) to replace with a greater depth (N '). The disadvantage here is the disproportionate increase in rudder forces and the change in the rudder profile. The side control cables usually used to control the rudder (N) would have to act on a driver, which remains in the fin. As is the case with elevators in the prior art, the driver then drives the interchangeable rudder (N, N ') by positive engagement. In this way, the review required release and reconnection of the control cables would be avoided.

Another difficulty with increasing span ratio is the design of the wings themselves, so that can be rebuilt between two approximately optimal wing configurations. According to the state of the art in high-performance gliders, which are to be competitive in different spans, the variation with alternative outer wings is achieved ( 1 ). Each half-wing is divided into at least two parts. The existing one or more parts inner wing (C) is always mounted. There are two alternately mountable outer wings (A, B). As an example, mention is made of a type having an inner wing of 5.5 m semi-span, to which either a 2 m long or a 3.5 m long outer wing can be mounted. This allows the aircraft to be used in both the 15m and the 18m class.

• • wird in der kleinen Spannweitenkonfiguration eine unverhältnismäßig große Masse sinnlos mitgeschleppt. Denn die große Konfiguration mit ihrer großen Spannweite und in der Regel höheren maximalen Abflugmasse definiert das Strukturgewicht des Innenflügels.
• • lässt sich in mindestens einer Konfiguration weder Flügelfläche noch Flügelgrundriss so gestalten, dass ein konkurrenzfähiges Segelflugzeug entsteht. Ursache ist der fixe Innenflügel, der mit seiner Zuspitzung einen Großteil der Flügeltiefenverteilung vorgibt.
• • Um die vorgenannten Probleme zu mildern, kann die Grenze zwischen Außen- und Innenflügel nach innen verschoben werden. Das führt aber dazu, dass ein zunehmender Teil des Flügels doppelt gebaut wird. Im Flugbetrieb bleiben dann in allen Konfigurationen große Flügelstücke ungenutzt am Boden.

The variation of the span is set with this concept a narrow limit. With larger difference of the outer wing lengths

• • In the small span configuration, a disproportionately large mass is meaninglessly dragged along. Because the large configuration with its large span and usually higher maximum take-off mass defines the structural weight of the inner wing.
• • In at least one configuration, neither the wing nor the wing layout can be designed to produce a competitive glider. The cause is the fixed inner wing, which predetermines a large part of the wing depth distribution with its taper.
• • To alleviate the aforementioned problems, the boundary between the outer and inner wings can be shifted inwards. But this means that an increasing part of the wing is built in duplicate. In flight mode, then in all configurations large wing pieces remain unused on the ground.

In a favorable embodiment, this problem is solved in the following way. Instead of replacing the outer wings, the wing is designed to have a constant chord section in the central region of the large configuration, which may optionally be let out. This area will typically, but not necessarily, attach directly to the fuselage to reduce the number of separation points. It is therefore referred to below as inner wing (P). In 7 an exemplary embodiment is shown as exploded views of the large and small span configuration. If the inner wing (P) is let out, the remaining outer wings (O) can be connected directly to the fuselage. As a result, despite large variations in span width, an approximately elliptical wing contour of high elongation can be achieved in both configurations. The oversized wing area for the small span configuration is removed. The outer wings (O) can also be divided into other items, for example, to increase the handiness.

The separation point of the wing in the plane of symmetry can be done conventionally with shear force connections, spar stubs (R, Q) and automatic control connections. It must be noted that the outer wings (O) also have the same geometry with respect to the transverse force connections, control connections, and the space for the stub shafts (R ', Q'), so that they are connected instead of the inner wing (P) can. This then again defines the geometry of the separation point at the outer end of the inner wing (P). As a result, not only at the fuselage-wing transition generally results in a V-position kink, but also at the separation point between inner wing (P) and outer wing (O).

There were already gliders in which wings were extended with an additional inner trapezoid with a rectangular outline. But either the inner trapezoid could not be let out, or it claimed only such a small part of the wing, that a change of the vertical stabilizer was not provided.

The SB10 of the Akaflieg Braunschweig (first flight 1972) uses the wings of the SB9, whereby these are infected as outer wings to a new, 8 m exciting inner wing with rectangular cross-section. However, with the SB10 it is not possible to omit the inner wing.

Richard Butler from the USA built inner wings for his ASW 17 S (first flight 1981) to increase the span from 20 m to 23 m. These inner wings could also be let out, the ratio of span variation is very small at 1.15: 1. The vertical stabilizer remained invariable.

The fs 29 of the Akaflieg Stuttgart (first flight 1975) is a glider that can change its span during flight from 19 m to 13.3 m by pushing the outer wings over the inner wings (telescopic wing), without changing the vertical stabilizer , Without the heavy inner wing, the plane can not be flown. A trudling test - in which the fin size is crucial - did not take place due to the telescopic mechanism.

In the patent CH 540 144 A the reversible conversion of a glider is described in a motor glider, by inserting motorized inner wing, but without addressing the problem of the vertical stabilizer.

In the utility model DE 20 2014 003 490 U1 is a specific construction of a fuselage for aircraft described, "characterized in that the V-tail with winglets (10, 11) are extended." However, it is not shown that the operation of the aircraft should be possible both with and without these winglets, or said extension is related to different span configurations. In order to achieve the enlargement of the rudder and thus also the rudder efficiency necessary with an increase in the span, rigid winglets appear unsuitable.

When changing the span to a large extent, other aspects must be considered:
In the prior art, wing flaps are used on performance gliders which adapt the wing profile to the current flight condition. These flaps also serve as ailerons (so-called flaperons). For the sake of simplicity, all end edge flaps are referred to below as flaperons, even if in individual cases they should not perform a transverse or arching function.

The brakes (S) are useful in a position where they work well and have little influence on the controllability. This is usually the case in the spanwise direction between the edge bow of the tailplane (D) and the inner end of the outer flaperons (Fa). If the brakes (S) are in this position in the small span configuration, they will be relatively far out in the large span configuration. Therefore, it makes sense to keep these brakes (S) small, and to install on the removable inner wing (P) another pair of air brakes (S '). In the small configuration, the airbrakes (S) may be assisted by a landing position where the middle flaperon (Fm) is knocked down, the outside flaperone (Fa) is knocked up. This limitation also increases the resistance. Dividing the airbrakes into two positions (S, S ') also has the advantage of blurring the local load peaks of the airbrake load latch, which are typically reflected in the sizing of the wing's dimensioning distribution of bending moment.

The maximum allowable take-off mass can be set independently for both span configurations. The values can be chosen so that the dimensioning loads of the outer wing (O) in both span configurations are nearly equal. This always makes efficient use of the structure.

In elaborate versions of the prior art, there are two pairs of flaperons for gliders up to 21 m, for larger wings three pairs of flaperons, which make different deflections depending on the control input. This concerns, for example, the aileron deflections, that is, the deflections of the flaperons in the event of alternating full rashes of the lateral control. The ailerons rashes are then large in the outer flaperons, small in the inner ones. This allows great roll rates with good circular flight characteristics to be combined. In the landing position, the inner flaperons strike down sharply, while the outermost ones assume a more neutral position. This allows steep approaches with good controllability about the longitudinal axis.

In a glider with a removable inner wing, a compromise has to be found for the Flaperon (Fm), which is innermost in the small span configuration, but sits in the middle in the large configuration. It would be useful to knock out the mentioned Flaperon (Fm) in the landing position, but less than the innermost Flaperon (Fi) in the large Span configuration. The outermost Flaperon (Fa) in all configurations assumes a somewhat more positive position in the landing position than usual in the prior art. So, with the small span, there is still a setback that increases resistance and improves controllability. At the same time, as required, even in the large span configurations, the pitch in the landing position over the span is increasing monotonously. Due to the still slightly positive rash of the outer flaperone (Fa) can be achieved that increases even in the small configuration of the maximum lift coefficient in the landing position.

In order to achieve sufficient roll turn over a large span, the flaperon (Fm), which is innermost in the small span configuration, will make larger aileron deflections than would an aircraft optimized for the small span. This is acceptable and still offers more potential for optimization than a single, full-span flaperon, as is sometimes used in the art.

In the prior art, the separation point between the fuselage and wing is located directly at the rounding between the fuselage and wing. In sophisticated designs, the profile and pitch angle of the innermost wing segment are adjusted to the flow conditions of the fuselage wing transition. However, the removable inner wing (P) must have an unaltered wing profile over its span. Otherwise, when the inner wing (P) is released, a jump in the contour between the fuselage and the outer wing (O) would result. Therefore, the removable inner wing (P) can have no adjustments to the flow conditions of the fuselage wing transition. Also, the outer wing (O) can not have such adjustments, since it comes to lie in a wide span configuration far from the fuselage. Therefore, it makes sense to place the separation point between the fuselage and wing at a greater distance from the plane of symmetry. As a result, a wing stub (T) remains firmly on the fuselage, which goes beyond the immediate rounding. The rounding is usually a saddle surface, while such a wing stub also includes a wing region in which the surface is approximately unwound. This wing stub is also advantageous in that the stubs (Q, R), which provide for a transmission of the bending moments by a pair of opposite transverse forces, can be made longer. As a result, the distance of the transverse forces can be greater, thus the transverse forces smaller, resulting in lighter hardware and lower adhesive stresses in Stummelinneren.

LIST OF REFERENCE NUMBERS

• A, B:

  alternately mountable outer wings

  C:

  inner wing

  D:

  tailplane

  e:

  Rudder, fin

  F:

  tail boom

  Fi:

  innermost flaperone in the large span configuration

  fm:

  middle flaperone; in the small span configuration innermost Flaperon

  Fa:

  extreme flaperone

  G, G ':

  tailwheel

  H:

  connecting piece

  I:

  Lateral bolt

  J:

  extension

  K:

  flap

  L:

  Tongue and groove connection

  M:

  Recording the tail wheel axle

  N, N ':

  rudder

  O:

  Outer wing; wing part

  P:

  Inner Wing; Wing section of constant chord depth; Wing part;

  Q, Q ':

  spar stubs

  R, R ':

  spar stubs

  S, S ':

  airbrake

  T:

  stub wings

Claims (9)

Glider or motor glider whose span can be varied before the flight by the choice of attached wing pieces, characterized in that the size of the vertical stabilizer (E) can be changed before the flight. A glider or motor glider according to claim 1, characterized in that the rudder (E) by an extension piece (J) is increased, and the extension piece (J) under the tail unit (F) and the existing vertical stabilizer (E) is mounted, wherein in the tail unit (F) the receptacle (M) for the tail wheel (G, G ') of the attachment is used. Glider or motor glider according to claim 1, characterized in that in the context of the upgrading of the aircraft by the pilot either a large or a small rudder (N, N ') can be mounted. Glider or motor glider according to claim 1, characterized in that it is an aircraft with T-tail and an intermediate piece (H) between the vertical stabilizer (E) and tailplane (D) can be used. Glider or motor glider according to one of the preceding claims, characterized in that the adaptation from the larger to the smaller span by letting out wing pieces constant chord depth (P), whereby the outer wing part (O) is offset inwards. A glider or motor glider according to claim 5, characterized in that there are brake flaps (S, S ') both on the part (O) of the wing, which is always mounted, and on the wing part (P), which can be let out. Glider or motor glider according to claim 5 or 6, characterized in that • the wings are provided with flaperons (Fi, Fm, Fa), and that in the landing position the flaperon (Fm) innermost in the small span configuration occupies a deflection which is more positive is, as in all its overland flight positions, but not more positive than the innermost flaperon (Fi) in the landing position, each with neutral aileron considered • and that in the small span configuration innermost Flaperon (Fm) makes ailerons rashes that at least are half as big as those of the outermost flaperone (Fa) A glider or motor glider according to claim 5, 6 or 7, characterized in that the maximum take-off mass with the large span is so much higher that the loads of each wing part (O, P) dimensioning its structure are approximately equal in all span configurations. Glider or motor glider according to claim 5, 6, 7 or 8, characterized in that the separation point between the fuselage and wing is displaced outward to the extent that on the hull beyond the immediate rounding between the fuselage and wing outgoing wing stub (T) is firmly attached.

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