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.
18-481: (Redirected from D-40 ) 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 ,
36-481: 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
54-536: A Canadian bus Nikon D40 , 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
72-524: A winglet and distribute weight more evenly across the wing spar. On fighter aircraft , they may also be fitted with hardpoints , for mounting drop tanks and weapons systems, such as missiles and electronic countermeasures . Wingtip mounted hose/drogue systems allow Aerial refueling of multiple aircraft with separation. Aerobatic aircraft use wingtip mounted crosses for visual attitude reference. Wingtip mounted smoke systems and fireworks highlight rolling aerobatic maneuvers. Some airshow acts feature
90-610: 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
108-507: 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
126-488: 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
144-410: Is the part of the wing that is most distant from the fuselage of a fixed-wing aircraft . Because the wing tip shape influences the size and drag of the wingtip vortices , tip design has produced a diversity of shapes, including: Winglets have become popular additions to high speed aircraft to increase fuel efficiency by reducing drag from wingtip vortices. In lower speed aircraft, the effect of
162-545: The Consolidated PBY Catalina , use retractable wingtips as floats. Moveable wingtips can affect the controlability of a wing. Wing warping the ends of the wing, produced roll control on the earliest of aircraft such as the Wright Flyer . The North American XB-70 Valkyrie raised and lowered its wingtips in flight to adjust its stability in supersonic and subsonic flight. Wingtips can also house
180-423: 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
198-562: 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 Wing tip A wing tip (or wingtip )
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#1732788101683216-502: 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
234-474: 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
252-527: The pilot touching or dragging the wingtip along the ground. Aircraft with a single main landing gear or very high aspect ratio wings such as gliders , may place small landing gear in the wingtips. Some uncommon designs, like the Rutan Quickie , and Convair XFY placed the main landing gear in the wingtips. Some early World War I aircraft used wooded skids on the wingtips to minimize damage on ground looping incidents. Several amphibious aircraft such as
270-599: The power plant or thrust of an aircraft. The EWR VJ 101 used tip mounted jets, the V-22 uses tilting wingtip mounted engines, and the Harrier uses wingtip thrust for stability while hovering. Rotary wing aircraft wingtips may be swept or curved to reduce noise and vibration. Some rotary wing aircraft place their propulsion in wingtip tip jets . Due to limited space within naval vessels , many naval aircraft possess folding wings and wingtips for storage purposes, minimizing
288-546: 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.
306-421: 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
324-606: The wingtip shape is less apparent, with only a marginal performance difference between round, square, and Hoerner style tips The slowest speed aircraft, STOL aircraft, may use wingtips to shape airflow for controllability at low airspeeds. Wing tips are also an expression of aircraft design style, so their shape may be influenced by marketing considerations as well as by aerodynamic requirements. Wing tips are often used by aircraft designers to mount navigation lights , anti-collision strobe lights , landing lights , handholds, and identification markings. Wing tip tanks can act as
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