| Akaflieg Stuttgart | |
|
HW100 - 45000
UAW55 - 105000 RRW100 - 175000 PKRR - 7500 |
Akaflieg Stuttgart F.1 (Akaflieg Stuttgart F.1 Fledermaus) F-1 Fledermaus Role - Research motor glider National origin - Germany Manufacturer - Akaflieg Stuttgart First flight - July 1933 Number built - 1 The Akaflieg Stuttgart F-1 Fledermaus (Bat) was a glider designed and built in Germany from 1932. Development The 'F.1' was the first glider designed and built at Akaflieg Stuttgart (Akademische Fliegergruppe) using a wind tunnel and innovative thinking. As built, the F.1 had no vertical tail, using rotatable wing-tip panels for roll and yaw control. The fuselage was curved to follow the downwash from the wing and rested solely on a single large skid under the forward fuselage, not having a tail-skid. The completely enclosed cockpit included a hanging control column, to simplify the control run, and airbrakes, for use on the ground, using the cockpit canopy. The F.1 entered its first competition at Rhön in 1933, but the technical committee insisted that the glider be given a conventional vertical tail, despite protests that the F.1 had already flown a 300 km distance task as built. The fliegergruppe acquiesced and built a vertical tail overnight, with the F.1 claiming several prizes during the competition. Specifications (F.1) (Data from Flugzeug-Typenbuch . Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944) General characteristics Crew: 1 Length: 5.53 m (18 ft 2 in) Wingspan: 16.6 m (54 ft 6 in) Height: 1.2 m (3 ft 11 in) Wing area: 15.44 m2 (166.2 sq ft) Length de-rigged: 8 m (26 ft) Width de-rigged (without tailplane): 14 m (46 ft) Height de-rigged: 1.4 m (4 ft 7 in) Aspect ratio: 19 Airfoil: root: Göttingen 535; mid-span: Göttingen 535 ; tip: Göttingen 527 Empty weight: 130 kg (287 lb) Gross weight: 210 kg (463 lb) Performance g limits: +8.8 (ultimate) Maximum glide ratio: 22 at 56 km/h (35 mph; 30 kn) Rate of sink: 0.58 m/s (114 ft/min) at 48 km/h (30 mph; 26 kn) Wing loading: 13.6 kg/m2 (2.8 lb/sq ft) Aircraft of comparable role, configuration, and era Rhönadler Akaflieg Stuttgart fs16 (Akaflieg Stuttgart fs16 Wipperstertz) Akaflieg Stuttgart fs16 Role - Glider aircraft National origin - Nazi Germany Manufacturer - Akaflieg Stuttgart First flight - February 1937 Number built - 1 The Akaflieg Stuttgart fs16, nicknamed Wippsterz (German: Wagtail) was a glider aircraft that was designed and built in Germany from 1936. Only one example of the design was constructed. Development Akaflieg Stuttgart wanted to build a glider with reasonable performance that was safe and simple to fly, the result was the fs16. The design employed a cantilever wing attached to the top of the fuselage; the rear portion of the fuselage was raised, similar to the Akaflieg Stuttgart F.1. The fs16 as constructed had no vertical tail, but used pivoting panels on the wingtips for roll and yaw control. It had no tail-skid, using a single large skid under the front fuselage with a spur extending rearwards for support and stability on the ground. Flight characteristics with the rotating wing-tip panels were not as expected so a conventional vertical fin on an extended rear fuselage, and ailerons constructed from fabric-covered Duralumin on the outer wing trailing edges, were added after initial flights. Specifications (Data from Flugzeug-Typenbuch . Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944) General characteristics Crew: 1 Length: 6.13 m (20 ft 1 in) Wingspan: 15.78 m (51 ft 9 in) Height: 2.14 m (7 ft 0 in) Wing area: 13.3 m2 (143 sq ft) Length de-rigged: 5.3 m (17 ft) Width de-rigged (without tailplane): 0.6 m (2 ft 0 in) Width de-rigged (with tailplane): 2.83 m (9 ft 3 in) Height de-rigged: 1.12 m (3 ft 8 in) Aspect ratio: 18.5 Airfoil: root: NACA 2318; mid-span NACA 2312 tip: NACA 0012 Empty weight: 144 kg (317 lb) Gross weight: 230 kg (507 lb) Performance Never exceed speed: 120 km/h (75 mph, 65 kn) g limits: +8 (ultimate) Maximum glide ratio: 24 at 65 km/h (40 mph; 35 kn) Rate of sink: 0.8 m/s (160 ft/min) at 55 km/h (34 mph; 30 kn) Wing loading: 17.5 kg/m2 (3.6 lb/sq ft) Similar aircraft Schleicher Rhönadler Akaflieg Stuttgart fs17 Akaflieg Stuttgart fs17 Role - Glider aircraft National origin - Nazi Germany Manufacturer - Akaflieg Stuttgart First flight - 21 March 1938 Number built - 1 The Akaflieg Stuttgart fs17 was a glider aircraft that was designed and built in Germany from 1936. It notably featured a prone seating position for its pilot. Development Realising that aircraft form drag is directly related to cross-sectional area of bodies moving through the air, the students of Akaflieg Stuttgart (Akademische Fliegergruppe - academic flying group) investigated methods of reducing the cross-sectional area of fuselage bodies, including the prone-position pilot, where the pilot lies horizontally with his body roughly parallel to the longitudinal axis of the fuselage. They noted an additional benefit of such a configuration is the pilot's increased resistance to the effects of 'g'. With very little previous research to take advantage of Akaflieg Stuttgart designed the FS 17 glider for flight trials of prone position cockpits. The fs17 was an all-wood low-wing cantilever monoplane with emphasis on good low-speed flight characteristics, to reduce the risk to the pilot in stalling accidents, and a maximum load factor of 14g. The fuselage was designed with increased stiffness, to provide increased crash protection for the pilot, and the wing leading edges formed torsion boxes. The pilot lay above the wing centre section under an extensively glazed canopy. Specifications (Data from Flugzeug-Typenbuch . Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944) General characteristics Crew: 1 Length: 5.1 m (16 ft 9 in) Wingspan: 10 m (32 ft 10 in) Height: 1.82 m (6 ft 0 in) Wing area: 12 m2 (130 sq ft) Aspect ratio: 6.33 Airfoil: root: NACA 23012; tip: NACA 0009 Empty weight: 84 kg (185 lb) Gross weight: 170 kg (375 lb) Performance Never exceed speed: 450 km/h (280 mph, 240 kn) g limits: +14 (ultimate) Maximum glide ratio: 19.8 at 81 km/h (50 mph; 44 kn) Rate of sink: 0.88 m/s (173 ft/min) at 64 km/h (40 mph; 35 kn) Wing loading: 14.17 kg/m2 (2.90 lb/sq ft) Akaflieg Stuttgart fs18 Akaflieg Stuttgart fs18a Role - Glider aircraft National origin - Nazi Germany Manufacturer - Akaflieg Stuttgart First flight - 21 July 1938 Number built - 1 The Akaflieg Stuttgart fs18a was a glider designed and built in Germany from 1938. It was characterized by a gull wing and was the first glider to have a retractable undercarriage. Only one example of the design was constructed. Development With the experience gained from the Rhön gliding competitions, the students at Akaflieg Stuttgart (Akademische Fliegergruppe - academic flying group) designed the fs18, which was able to turn tightly in thermals and had a relatively low sink rate, over the six months preceding the next Rhön competition at Wasserkuppe. The result was the fs18 which was a high-wing cantilever monoplane with gulled centre section, to ensure that the wings joined the fuselage at 90 degrees, rectangular midsection and tapered outer section. Flaps were fitted to the trailing edge of the midsection to 30% chord, and ailerons were mounted on the trailing edges of the outer wing sections. The fuselage consisted of the cockpit pod smoothly narrowing to a boom-like rear fuselage supporting the tail unit. The main undercarriage was manually retractable into an enclosed wheel well behind the cockpit. After the first flight on 21 July 1938, testing of the fs18a continued until 7 December 1938 when the fs18 crashed, killing pilot Ernst Scheible. Specifications (Data from Flugzeug-Typenbuch . Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944) General characteristics Crew: 1 Length: 7.1 m (23 ft 4 in) Wingspan: 18 m (59 ft 1 in) Height: 1.15 m (3 ft 9 in) Wing area: 18 m2 (190 sq ft) Length de-rigged: 10 m (33 ft) Width de-rigged (without tailplane): 1 m (3 ft 3 in) Width de-rigged (with tailplane): 2.5 m (8 ft 2 in) Height de-rigged: 1.25 m (4 ft 1 in) Aspect ratio: 18 Airfoil: root: NACA 43015; mid-span: NACA 43012 ; tip: NACA 0012 Empty weight: 200 kg (441 lb) Gross weight: 300 kg (661 lb) Performance g limits: +8 (ultimate) Maximum glide ratio: 30 at 70 km/h (43 mph; 38 kn) Rate of sink: 0.53 m/s (104 ft/min) at 50 km/h (31 mph; 27 kn) Wing loading: 16.68 kg/m2 (3.42 lb/sq ft) Aircraft of comparable role, configuration, and era DFS Weihe Akaflieg Stuttgart fs23 (Akaflieg Stuttgart fs23 Hidalgo) Akaflieg Stuttgart fs23 Role - Glider aircraft National origin - West Germany Manufacturer - Akaflieg Stuttgart Designer - R. Eppler & H. Nägele First flight - 1 February 1966 Number built - 1 The Akaflieg Stuttgart fs23, nicknamed Hidalgo (Spanish: "Nobleman"), was a glider aircraft that was designed and built in West Germany from 1953. It was lighter than most contemporaries. Only one example of the design was constructed, which was destroyed in a fatal crash in 1971. Development Design of the fs23 was started in 1953 and took thirteen years, including a hiatus while the fs24 Phönix was developed. The goal of the fs23 designers was a lightweight high-performance glider to meet the proposed 13m mini-standard class for competition gliders. To achieve this goal the students at Akaflieg Stuttgart thoroughly tested fibreglass re-inforced composites, as well as birch ply and balsa/fibreglass sandwiches, for E- and G-modulus, compressive and torsional strength as well as bonding and rivetting methods. Once the testing was complete the aircraft could be designed to ensure adequate strength with light weight, (1/3 to 2/3 the weight of typical gliders of the time), and good aerodynamic qualities, the result being the fs23 Hidalgo. Built primarily of balsa core sandwiched in fibreglass, the fs23 was a high-wing, high aspect ratio, cantilever monoplane with moderate dihedral and -6o sweep, (to reduce the tail moment required and thus the size and weight of the rear fuselage and tail unit), and a V-tail. A fixed undercarriage and a brake parachute were used. Flight trials began on 1 February 1966 demonstrating that the fs23 had sensitive controls, side-slipped well and gave adequate warning of a stall. It recovered easily from a spin, within half a turn. In 1967 the fs23 suffered severe tail flutter and the pilot was thrown out of the cockpit, descending by parachute, as the aircraft dived towards the ground from 1500 meters altitude. The aircraft landed with minimal damage and was repaired to continue the test programme until July 1971 when the fs23 crashed a second time, with the pilot, Heinz Jahn, losing his life. Specifications General characteristics Crew: 1 Length: 5.0 m (16 ft 5 in) Wingspan: 13 m (42 ft 8 in) Height: 0.89 m (2 ft 11 in) Wing area: 7.0 m2 (75 sq ft) Aspect ratio: 24.1 Airfoil: FX 61-184 bei (root) / FX 61-168 bei (23% semispan) / FX 61-147 bei (70%) / FX 60-126 bei (88%) Empty weight: 102.5 kg (226 lb) Gross weight: 190 kg (419 lb) Aircraft of comparable role, configuration, and era Standard Austria Akaflieg Stuttgart fs24 (Akaflieg Stuttgart fs24 Phönix) fs24 Phönix Role - Sailplane National origin - West Germany Manufacturer - Akaflieg Stuttgart Designer - Richard Eppler and Hermann Nägele First flight - 27 November 1957 Number built - 9 The Akaflieg Stuttgart fs24, nicknamed Phönix (German: "Phoenix"), was a glider designed and built in West Germany from 1951. Design and development The fs24 was the first glider to use fibreglass in its construction. The development of modern aerofoil sections for gliders required very accurate reproduction with smooth surfaces, using tolerances that were extremely difficult to achieve using conventional wood or metal construction, but could be achieved by using composite materials laid up in a mould. The design of the fs24 was started at Akaflieg Stuttgart, (Akademische Fliegergruppe - academic flying group), by Richard Eppler and Hermann Nägele in 1951. Originally it was constructed of balsa wood with a strengthened outer layer of paper and glue layers, which proved unsatisfactory. The project was abandoned until a grant for further research was received from the state of Baden-Württemberg. By then glass fibre reinforced polyester resin was available and so it was redesigned using a balsa wood/glass fibre sandwich, with the load-bearing points and the edge of the cockpit canopy strengthened with plywood. The first flight was made on 27 November 1957, and good performance and excellent handling were demonstrated, especially in weak thermal conditions. The prototype had a conventional tail unit and a bumper instead of a conventional undercarriage. Airbrakes were fitted on the underside of the wing trailing edges. Bölkow built eight fs24s, designated Phönix T, differing in the use of a T-tail and retractable undercarriage. Variants fs24 Phönix 16m sailplane certified in January 1959 and manufactured by Akademische Fliegergruppe Stuttgart. fs24 Phönix TO 16m sailplane with a T-tail certified in May 1960 and manufactured by Apparatebau Nabern. fs24 Phönix T 16m sailplane certified in April 1961 and manufactured by Apparatebau Nabern. Surviving aircraft The prototype fs24 Phönix is on display at the Deutsches Museum in Munich, Germany. D-8353 is part of the collection of the Deutsches Segelflugmuseum at Wasserkuppe, Germany. Specifications (Data from The World's Sailplanes: Die Segelflugzeuge der Welt: Les Planeurs du Monde) General characteristics Crew: 1 Length: 6.84 m (22 ft 5 in) Wingspan: 16 m (52 ft 6 in) Height: 0.95 m (3 ft 1 in) Wing area: 14.36 m2 (154.6 sq ft) Aspect ratio: 17.83 Airfoil: EC 86 (-3) - 914 Empty weight: 161.7 kg (356 lb) Max takeoff weight: 265 kg (584 lb) Performance Stall speed: 43 km/h (27 mph, 23 kn) Never exceed speed: 140 km/h (87 mph, 76 kn) Rough air speed max: 100 km/h (62.1 mph; 54.0 kn) Aerotow speed: 100 km/h (62.1 mph; 54.0 kn) Winch launch speed: 90 km/h (55.9 mph; 48.6 kn) g limits: +4 -2 Maximum glide ratio: ~37 at 77-80.2 km/h (47.8-49.8 mph; 41.6-43.3 kn) Rate of sink: 0.53 m/s (104 ft/min) at 69.2 km/h (43.0 mph; 37.4 kn) Wing loading: 18.5 kg/m2 (3.8 lb/sq ft) Aircraft of comparable role, configuration, and era Hirth Hi25 Kria fs24 in the Deutsches Museum in Munich FS 24 Stamp Akaflieg Stuttgart fs25 (Akaflieg Stuttgart fs25 Cuervo) fs25 Cuervo Role - Glider National origin - West Germany Manufacturer - Akaflieg Stuttgart First flight - 30 January 1968 Number built - 1 Developed from - Akaflieg Stuttgart fs23 Hidalgo The Akaflieg Stuttgart fs25, nicknamed Cuervo (Spanish: Raven) is a glider designed and built in Germany from 1968. Development With the completion of the fs23 Hidalgo and flight testing it was found that some of the expected results were not forthcoming. Through use of the UNIVAC 1107 computer, at the Institut für Statik und Dynamik of the University of Stuttgart, there was found to be no possible improvement of the wing section and arrangement of the fs23. The students then concentrated on the fuselage of a new aircraft using the wing of the fs23 extended to 15m span, with drag reduced to a minimum by reducing the wetted area of the fuselage, as a whole, and reducing the sectional area dramatically aft of the wing. The long thin tail boom, constructed with aluminium alloy, was donated by VFW (Vereinigte Flugtechnische Werke) at Speyer and attached to the tubular steel fuselage centre section structure. Tests were carried out to define the best method of transferring loads between fibre-glass components and other materials. Rivetting had been used on the fs23 through reinforcement with birch plys, but the best results were obtained by re-inforcing with extra fibreglass plys and direct bonding without screws, bolts or rivets. The reduced cross-section front fuselage was constructed from fibreglass/balsa sandwich attached to the internal centre section tubular steel structure with a reclined seating position and plexiglass canopy hinging to the rear. After the first flight, on 30 January 1968, Helmut Reichmann (world standard and 15m class champion) flew the fs25 in the German national gliding championship, where he demonstrated the harmony of the controls, agility and the excellent climb performance due to the high aspect ratio and low wing loading. Development of the fs25 has been carried out in France at the ENSMA - Ecole Nationale Supérieure de Mécanique et D'Aérotechnique as part of the Société Scientifique de Recherche et de Promotion du Planeur Léger. The ENSMA FS-25 F Cuervo has modifications to the internal structure as well as a retractable mainwheel, improved canopy and modified ailerons. A two-seat version has also been developed at ENSMA, as the ENSMA Two-seater. Specifications General characteristics Crew: 1 Length: 6.48 m (21 ft 3 in) Wingspan: 15 m (49 ft 2.5 in) Height: 0.80 m (2 ft 7.5 in) Wing area: 8.54 m2 (91.9 sq ft) Aspect ratio: 26.4:1 Airfoil: - FX 66-S-196 at 0,04 b/2 - FX 61-184 at 0,17 b/2 - FX 61-168 at 0,33 b/2 - FX 61-147 at 0,81 b/2 - FX 60-126 at 0,90 b/2 Empty weight: 157 kg (346.1 lb) Gross weight: 250 kg (551.16 lb) Performance Maximum glide ratio: 38.5 Rate of sink: 0.60 m/s (118.1 ft/min) Akaflieg Stuttgart fs26 (Akaflieg Stuttgart fs26 Moseppl) fs26 Moseppl Role - Motor glider National origin - West Germany Manufacturer - Akaflieg Stuttgart First flight - 25 September 1970 Number built - 1 The Akaflieg Stuttgart fs26 Moseppl is a German single-seat motor glider with twin fins and rudders designed and built by Akaflieg Stuttgart. First flown on the 25 September 1970 it was designed as an experiment and not intended for production. Design The fs26 Moseppl is a cantilever high-wing monoplane with a monocoque nacelle fuselage and a glassfibre/balsa sandwich wing structure, fitted with airbrakes but no flaps or ailerons. To make room for the engine the Moseppl has twin fins and rudders attached to the wing trailing edge with an all-moving tailplane between the tops of the vertically surfaces. The pilot sits in an enclosed cockpit with a transparent canopy and the landing gear is a retracting rear monowheel and non-steerable nosewheel. The rear-mounted engine is a 26 hp (19 kW) Solo-Hirth engine with a variable pitch pusher propeller. Specifications (Data from Jane's All the World's Aircraft 1973-74) General characteristics Crew: 1 Length: 3.94 m (12 ft 11.75 in) Wingspan: 12.60 m (41 ft 4 in) Height: 2.08 m (6 ft 9.75 in) Wing area: 13.2 m2 (142 sq ft) Aspect ratio: 12.1 Empty weight: 250 kg (551 lb) Gross weight: 360 kg (793 lb) Powerplant: 1 × Solo-Hirth engine , 19 kW (26 hp) Performance Maximum speed: 200 km/h (124 mph, 108 kn) Stall speed: 75 km/h (47 mph, 41 kn) Maximum glide ratio: 24 Rate of sink: 1.0 m/s (200 ft/min) Akaflieg Stuttgart fs28 (Akaflieg Stuttgart fs28 Avispa) fs28 Avispa Role - Two seat light aircraft National origin - West Germany Designer - Akaflieg Stuttgart First flight - 20 December 1972 Number built - 1 The Akaflieg Stuttgart fs28, nicknamed Avispa (Spanish: Wasp) is a single engine, twin boom pusher configuration light sports and utility aircraft designed at the University of Stuttgart in West Germany in the 1970s. Unusually, it has an inverted V-tail. The sole example remained active as of 2010. Design and development The Akaflieg Stuttgart or Akademische Fliegergruppe Stuttgart (English: The Stuttgart Academic Flying Group) is one of some fourteen German student flying groups attached to and supported by their home Technical University. Several have designed and built aircraft, often technically advanced and leading the development of gliders in particular. The fs28 was their first powered aircraft. The project, supported by the Fraunhofer Society and the Ministry of Economics of Baden-Württemberg, was intended to transfer the knowledge about high performance aerodynamics and composite materials gained from glider design to light powered aircraft. The fs28 is a twin-boom, pusher configuration low mid-wing monoplane. The wing has an Eppler profile, quite new in the 1970s, and is straight tapered with a swept leading edge and unswept trailing edge, resulting in 6.75° sweep at quarter chord. It is constructed from a sandwich of glass fibre and rigid foam and has 4.5° of dihedral. Fowler flaps, in two sections separated by the tail booms, fill the trailing edge out to the plain, untabbed ailerons. Accommodation and engine are in a central nacelle of glass reinforced plastic/honeycomb sandwich. Side-by-side seating is enclosed under a generous, three section canopy entered via upward, centreline hinged doors. A 115 hp (86 kW) flat four Lycoming O-235 piston engine, mounted in the rear of the nacelle with its output shaft well above the wing and booms and air-cooled via a semi-annular intake behind the cabin, drove a three-blade pusher propeller with a large spinner, designed to minimise noise. The three blade propeller was later replaced by a two-blade one. The tail booms are slender and linked at the rear by the unusual inverted Vee empennage. The straight edged, fixed rear surfaces are constructed as the wing but the control surfaces are fabric covered, with spring tabs. The fs28 has a retractable tricycle undercarriage with glass fibre shock absorbers, mainwheel hydraulic brakes and a steerable nosewheel. The sole fs28, V-1, D-EAFS, made its first flight on 20 December 1972. Operational history The fs28 was seriously damaged in an accident in May 1981 and its permit to fly (PTF) lapsed that November. With no rebuild under way, the registration D-EAFS was reallocated to another type in 1990. However, V-1 was rebuilt, regaining its PTF in July 1997, when it was registered as D-EKFS. It was on the German civil aircraft register in 2010, remaining active. Specifications Data from Jane's All the World's Aircraft 1974-75. All performance figures are at the maximum take-off weight. General characteristics Crew: Two Length: 7.20 m (23 ft 7 in) Wingspan: 9.40 m (30 ft 10 in) Aspect ratio: 7 Airfoil: Eppler 530 Empty weight: 640 kg (1,411 lb) Max takeoff weight: 950 kg (2,094 lb) Fuel capacity: 115 L (25.3 I,p gal; 30.4 US gal) Powerplant: 1 × Lycoming O-235-E2A air-cooled flat four, 86 kW (115 hp) Propellers: 3-bladed Hoffmann variable pitch pusher. Performance Maximum speed: 270 km/h (170 mph, 150 kn) Cruise speed: 250 km/h (160 mph, 130 kn) at 75% power Never exceed speed: 338 km/h (210 mph, 183 kn) Range: 1,000 km (620 mi, 540 nmi) at least, with 30 min reserve Wing loading: 71 kg/m2 (15 lb/sq ft) Landing speed: 85 km/h (53 mph; 46 kn) Akaflieg Stuttgart fs29 (Akaflieg Stuttgart fs29 TF) Akaflieg Stuttgart fs29 Role - Glider National origin - West Germany Manufacturer - Akaflieg Stuttgart First flight - 15th of June 1975 Number built - 1 The Akaflieg Stuttgart fs29 TF Stadt Stuttgart is a glider designed and built in Germany from 1972. Development The fs29 was designed and built to research the telescopic variable span wing. With the wing at full extension the fs29 could thermal successfully in very weak conditions and land safely in small spaces, conversely with the wing fully retracted the fs29 could cruise between lift at higher speeds, improving performance in distance/speed competitions, as well as perform aerobatics to higher load factors with faster control response. Construction of the fs29 was as follows: 1. Inner wing: Spar: Carbon Fibre Epoxy. Skin: Glassfibre Re-inforced Epoxy + Foam Sandwich. 2. Outer wing: Rectangular section: Carbon Fibre Epoxy Skin. Trapezoidal Section: Glassfibre Re-inforced Epoxy + Foam Sandwich. 3. Fuselage Structure: Welded steel tubing. 4. Cockpit: Glassfibre Re-inforced Epoxy + Foam Sandwich. 5. Tail Boom Skin: Aluminum Alloy. 6. Tail Unit: Glassfibre Re-inforced Epoxy + Foam Sandwich (derived from the tail of the Schempp-Hirth Nimbus-2). Extension and retraction of the outer wings was made by a screw jacks and nuts operated by the pilot pumping a handle via two-way free-wheel mechanisms, toothed belts and torque shafts which pulled or pushed the outer wings over the inner wings as required. The gap between the inside of the outer wing and the skin of the inner wing could be as much as 3mm without causing excess drag or affecting the flying qualities. The fs29 was demonstrated in flight at the 1996 ILA airshow at Berlin Schönefeld Airport, along with the Akaflieg Braunschweig SB-10 and SB-13. The sole fs29 was damaged in an accident during the summer of 1997, but is being re-built; meanwhile the fs29 can be seen at the Deutsches Museum in Munich. Specifications General characteristics Crew: 1 Length: 7.16 m (23 ft 6 in) Wingspan: 13.3-19 m (43 ft 8 in - 62 ft 4 in) Height: 0.78 m (2 ft 6.5 in) Wing area: 8.56-12.65 m2 (92.14-136.16 sq ft) Aspect ratio: 20.67 - 28.54 Airfoil: Rectangular part: FX 73 -170 Trapezoidal part: FX 73 - K - 170/22, β=0° Empty weight: 357 kg (787 lb) Gross weight: 450 kg (992 lb) Akaflieg Stuttgart fs31 Akaflieg Stuttgart fs31 Role - Glider National origin - West Germany Manufacturer - Akaflieg Stuttgart First flight - 30 December 1981 Number built - 1 Developed into - Schleicher AS 22-2 / Akaflieg Stuttgart fs33 / Akaflieg Braunschweig SB 15 The Akaflieg Stuttgart fs31 Ferdinand Porsche is a tandem seat, dual control training glider designed and built in Germany between 1977 and 1981. The aircraft was intended to have high performance, yet to be robust enough for student use. It was not intended for production and remains in service with the Akaflieg after almost 40 years and 7,100 flying hours. Design and development The Akaflieg Stuttgart or Akademische Fliegergruppe Stuttgart (English: The Stuttgart Academic Flying Group) is one of some fourteen German student flying groups attached to and supported by their home Technical University. Several have designed and built aircraft, often technically advanced and leading the development of gliders in particular. The students of the Stuttgart Akaflieg designed the fs31 as a high performance, tandem seat training sailplane to replace their earlier aircraft, further inspired by the purchase of a set of wings from the Grob G 103 Twin Astir prototype in 1977. Furthermore, the then new carbon Kevlar hybrid material was to be used to reduce weight. Energy dissipation and a locally strong cockpit area were further design objectives. Benign stall characteristics and a strong, long-stroke, monowheel undercarriage also make it suitable for student pilots. The fs31 has mid-mounted, straight tapered wings with 4° of dihedral, taken from the Twin Astir prototype. Its T-tail, from the Glasflügel 604, has a narrow chord, weakly tapered tailplane. The aircraft's control surfaces are made from a Kevlar-sandwich. Instructor and pupil sit in tandem in a cockpit placed forward of the wing, fitted with dual controls, under a long, single-piece canopy. The fuselage, which narrows to a slender boom behind the wing trailing edge, is similar to that of the Akaflieg Stuttgart fs29, though carbon/Kevlar replaces the earlier aircraft's GRP polymeric foam sandwich structure. Furthermore, the fuselage shells are split horizontally instead of vertically to improve pilot safety during a crash landing by eliminating a seam on the underside of the cockpit. The undercarriage is retractable and is also based on that of the fs29. The fs31 first flew on 30 December 1981. Some improvements were made to the wing root-fuselage junction during flight testing in the summer of 1982. The aircraft's fuselage design served as the basis for the Schleicher AS 22-2, later developed into the ASH 25, the Akaflieg Stuttgart fs33, and the Akaflieg Braunschweig SB 15. Operational history The sole fs31 was still undergoing field trial when it won the Klippeneck gliding competition of July 1982. It entered service with the Akaflieg Stuttgart in April 1983 and since then it has served in its intended role of trainer for almost 40 years, logging over 7,100 flying hours and 23,000 takeoffs. Specifications (Data from Akaflieg Stuttgart) General characteristics Crew: 2 Length: 8.82 m (28 ft 11 in) Wingspan: 17.50 m (57 ft 5 in) Wing area: 17.76 m2 (191.2 sq ft) Aspect ratio: 17.2 Airfoil: Eppler E 603 modified Empty weight: 397.79 kg (877 lb) Max takeoff weight: 560 kg (1,235 lb) Performance Stall speed: 60 km/h (37 mph, 32 kn) Never exceed speed: 250 km/h (160 mph, 130 kn) Akaflieg Stuttgart fs32 (Akaflieg Stuttgart fs32 Aguila) fs32 Aguila Role - Glider National origin - Germany Manufacturer - Akaflieg Stuttgart First flight - 18 February 1992 Number built - 1 The Akaflieg Stuttgart fs32, nicknamed Aguila (Spanish: Eagle) is a sailplane designed and built in Germany in 1992. Specifications (Data from Akaflieg Stuttgart, All-Aero) General characteristics Crew: 1 Length: 6.62 m (21 ft 9 in) Wingspan: 15.00 m (49 ft 3 in) Wing area: 9.94 m2 (107.0 sq ft) Aspect ratio: 22.65 Airfoil: FX 81-K-144/20 Empty weight: 255 kg (562 lb) Max takeoff weight: 500 kg (1,102 lb) Performance Maximum glide ratio: 43:1 at 105 km/h (65 mph; 57 kn) Rate of sink: 0.6 m/s (120 ft/min) at 85 km/h (53 mph; 46 kn) Wing loading: 50.3 kg/m2 (10.3 lb/sq ft) Akaflieg Stuttgart fs33 (Akaflieg Stuttgart fs33 Gavilán) fs33 Gavilán Role - Glider National origin - Germany Manufacturer - Akaflieg Stuttgart First flight - 28 May 1998 Number built - 1 The Akaflieg Stuttgart fs33 Gavilán (Spanish: Hawk) is a high-performance two-seater class sailplane designed and built by Akaflieg Stuttgart. Design and Development Development of the fs33 began in 1990 in response to the redefinition of the FAI two-seater Competition Class in 1989. Additionally, the aircraft should be of high performance, while also possessing pleasant handling characteristics and being viable for regular usage. The design itself was to be based on experiences gained from older prototypes and production aircraft. The project was also supposed to be completed quickly. This led among other things to the use of pre-existing molds to reduce development and construction time. A further focus of the project was safety. To achieve the above-mentioned goals, the fuselage molds of the Akaflieg Stuttgart fs31 were reused. Calculations were done based on the fs31's fuselage to determine the optimal geometry and mass for the vertical fin and tailplane, which led to the use of the fin of a Nimbus-3D and tailplane of a Nimbus-4D, though slightly modified to fit the fuselage. Furthermore, most of the control rods in the cockpit, the wheel brakes, and the rear lift pin tube were taken over from the Schleicher ASH 25. To create the wings, the wing molds of the Akaflieg Stuttgart fs32 were taken and extended inwards by 2,5 meters. Unlike in the fs32, the fs33 doesn't possess slotted flaps due to their complexity, instead using regular flaperons. Due to the lower than expected wing area gain, lightweight construction became an important factor to keep the design's wing loading within acceptable levels. The fs33 is a two-seater glider with a mid-mounted triple-trapezoidal wing. It has a wingspan of 20 meters and its wings are each equipped with three flaperons along the entire span and optional winglets. Operation of the flaperons is controlled by a mixer located at the wing root and the wings' control connections with the fuselage are automatic. The aircraft is almost entirely made out of carbon fiber composites, with the cockpit region being instead made out of a carbon-kevlar hybrid. Carbon fiber rovings were used to build the wing spars, while the skin was made of carbon fiber scrims (de) as a weight saving measure. Both pilots sit in tandem in a cockpit placed forward of the wing, fitted with dual controls, under a long, single-piece canopy. The fuselage is split horizontally, as with the fs31, instead of vertically to improve pilot safety during a crash landing by eliminating a seam on the underside of the cockpit. As an additional safety feature, the wings were designed to break off in the event of a crash landing. Originally the fs33 had an undercarriage constructed from carbon fiber composites with steel fittings to reduce weight, though this was later replaced with a steel one following the aircraft's crash. New winglets were built for the fs33 in 2016. Operational history First public display of the aircraft was during the AERO Fair of 1997 in Friedrichshafen. The fs33 achieved its first flight on 28 May 1998 in Aalen-Elchingen. Flight tests in the following years showed that the airbrakes were prone to spontaneously deploying, though this could usually be rectified by simply retracting the airbrakes. There were however two cases in which the airbrakes spontaneously deployed and jammed. The first led to a cancellation of tests and a safe landing on the airfield. The second case of jamming, this time of both airbrakes, led to a crash landing on 11 June 2000, which heavily damaged the aircraft's wings, fuselage, and undercarriage, though both pilot and passenger remained unhurt. Repairs, which were almost cancelled due to the extensive amount of damage along with the start of the Akaflieg Stuttgart fs34 project, began in October 2000. Work on the wings was done with assistance from Rolf Schmid from Technoflug. Repairs were finished by 2002, with the aircraft flying again on 15 May of that year. Damages were discovered on the aileron hinges in 2014, leading to a complete replacement of the ailerons. The aircraft was again taken out of service in 2016 due to damages to one of the wings. The fs33 is commonly used by the Akaflieg Stuttgart for gliding competitions. Specifications (fs33) (Data from Akaflieg Stuttgart) General characteristics Crew: 2 Length: 8.98 m (29 ft 6 in) Wingspan: 20.00 m (65 ft 7 in) Wing area: 14.43 m2 (155.3 sq ft) Aspect ratio: 27.7 Airfoil: AH 81-K-144/17 Empty weight: 408.5 kg (901 lb) Max takeoff weight: 640 kg (1,411 lb) Performance Stall speed: 74 km/h (46 mph, 40 kn) Never exceed speed: 280 km/h (170 mph, 150 kn) Wing loading: 32.6-44.35 kg/m2 (6.68-9.08 lb/sq ft) The fs33 in flight Logo of the fs33 project Three-view drawing of the fs33 |