The Akaflieg Darmstadt D-40 is an experimental variable geometry single seat sailplane , fitted with almost full span, camber changing flaps for optimum aerodynamics in weak thermals and integrated into the wing so as to minimise flap tip drag. One flew successfully but the D-40, like other variable geometry sailplanes, was not commercialised.
15-473: D40 may refer to: Akaflieg Darmstadt D-40 , a German sailplane D40 Navara , a Nissan pickup truck D40 road (Croatia) Dupuy D-40 , a French monoplane HMS Searcher (D40) , a Ruler -class escort carrier of the Royal Navy LNER Class D40 , a class of British steam locomotives New Flyer D40 , a Canadian bus Nikon D40 ,
30-481: A spar built from CRP rovings and GRP-balsa webs . The skin of both wing and flaps is an ARP/CRP/balsa sandwich; the flaps have CRP stringers . In plan the wings are straight tapered, with an increase in taper close to the tips; these outboard sections carry the short span ARP ailerons . The wing has 1° of dihedral and is swept forward at 2.3° at 25% chord . There are Schempp-Hirth upper surface airbrakes slightly forward of mid-chord near to mid-span. When
45-502: A wing is its rear edge, where the airflow separated by the leading edge meets. Essential flight control surfaces are attached here to control the direction of the departing air flow, and exert a controlling force on the aircraft. Such control surfaces include ailerons on the wings for roll control, elevators on the tailplane controlling pitch , and the rudder on the fin controlling yaw . Elevators and ailerons may be combined as elevons on tailless aircraft . The shape of
60-505: A digital camera [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=D40&oldid=1132531422 " Category : Letter–number combination disambiguation pages Hidden categories: Short description
75-601: Is a GRP shell, slender aft of the wings and with a T-tail with straight tapered surfaces. The rather wide cockpit occupies most of the deeper forward fuselage and has a long, one piece, front hinged canopy . A retractable monowheel undercarriage was assisted by a tail bumper. Initially the D-40 proved difficult for the relative novices of the Akaflieg to fly. In particular the short ailerons were lacking authority. The more experienced Helmut Reichmann did show, at one competition, that
90-498: Is different from Wikidata All article disambiguation pages All disambiguation pages Akaflieg Darmstadt D-40 The Akademische Fliegergruppe of the Technical University of Darmstadt ( Akaflieg Darmstadt ) was first formed in 1921. It was, and is, a group of aeronautical students who design and construct aircraft as part of their studies and with the help and encouragement of their University. Design work on
105-488: Is increased by 21% with the flaps extended. Although this arrangement avoids the vortexes at the flap tip, like any area increasing method used on a fixed span wing it results in a lower aspect ratio and hence a lower lift to drag ratio. The D-40 is constructed from a mixture of plastic-fibre composites , glass reinforced plastic (GRP), carbon fibre reinforced plastic (CRP) and aramid reinforced plastic (ARP) with some use of balsa wood. The shoulder mounted wing has
120-423: The 1938 Akaflieg Hannover AFH-4 and the later LET L-13 Blaník and Beatty-Johl BJ-2 , had added large area slotted Fowler flaps on the inner part of the wing to increase camber and add area when extended. These satisfactorily reduced stall speed and with it the turn radius, but disappointed hopes of improving climb rates because of vortex generation ( induced drag ) at the tips of the flaps, seriously decreasing
135-589: The D-40 outperformed the other sailplanes present under weak thermal conditions, as hoped for. The ailerons were redesigned and tall, narrow winglets added, which much improved the handling. In the end nothing became of any of the variable geometry glider designs. They were too complex for club use and significantly increased the pilot's workload. Data from Jane's All the World's Aircraft 1987/8 General characteristics Performance Trailing edge The trailing edge of an aerodynamic surface such as
150-492: The flaps, pivoted immediately inboard of the ailerons, are deployed the wing trailing edge becomes almost straight, making the plan almost triangular, and 12° of washout is generated by the now strongly cambered inner sections. This produces a lift distribution close to that of the ideal elliptical wing , with its minimum induced drag . The D-40 uses the fuselage and empennage of the Rolladen-Schneider LS3 . This
165-466: The lift to drag ratio. A solution to this problem was to extend the whole trailing edge, including the ailerons , and this route was taken by both the disappointing, heavy and complicated Operation Sigma Sigma , the more successful but still heavy and complex Akaflieg München Mü27 and the World Championship winning 15 m class Akaflieg Braunschweig SB-11 . These last three designs changed
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#1732859129786180-406: The trailing edge is of prime importance in the aerodynamic function of any aerodynamic surface. A sharp trailing edge is always employed in an airfoil. George Batchelor has written about: Other sharp-edged surfaces that are attached to the trailing edges of wings or control surfaces include: Other equipment that may be attached to the trailing edges of wings include: The trailing edge is where
195-405: The upper and lower surfaces of a wing meet. The angle between the upper and lower surfaces at the trailing edge is called the trailing edge angle . If the trailing edge angle is zero it is described as a cusped trailing edge. In two-dimensional flow around a uniform wing of infinite span, the slope of the lift curve is determined primarily by the trailing edge angle . The slope is greatest if
210-546: The variable wing geometry D-40 began in 1980 but the first flight did not take place until 15 August 1986. As understanding of thermal soaring grew in the 1930s, glider pilots and designers became aware of two conflicting requirements for cross country flights. The aircraft needed good climb characteristics and low stalling speeds to enable tight turns within thermals but high speeds in the sinking air between them. These respectively called for low and high wing loadings on wings with high and low camber. Several designs, e.g.
225-421: The wing geometry by extending the wing rearwards at right angles to the trailing edge. Akaflieg Darmstadt took a different approach, pivoting the single piece flap near the tip and sliding it out from within the wing trailing edge , gaining the mechanism the nickname "penknife wing". As it is extended, a track in the fuselage side guides the thin flap into its high camber position at the wing root . The wing area
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