Akaflieg Braunschweig
HW100 - 45000
UAW55 - 105000
RRW100 - 175000
PKRR - 7500
 Akaflieg Braunschweig SB-5 Danzig

SB-5
Role - Single seat Standard Class glider
National origin - West Germany
Manufacturer - Fa Eichelsdörfer, Bamberg
First flight - 3 June 1959
Number built - 100+

The Akaflieg Braunschweig SB-5 is a German single-seat Standard Class sailplane designed and prototyped by students of Brunswick University. More than 100 were built to their design, in several different variants.
Design
The Akaflieg Braunschweig or Akademische Fliegergruppe Braunschweig (English: The Brunswick Academic Flying Group) is one of some fourteen German undergraduate 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 SB-5 is a cantilever shoulder-wing monoplane with a plywood monocoque fuselage which has an outer fibre glass skin, a single spar wooden wing with plywood skinning, and a V-tail. Its wing, with a constant chord centre section and tapered outer panels, has 2.50° of dihedral and Schempp-Hirth airbrakes at 50% chord. The pilot has an enclosed cockpit with a Plexiglass canopy and the landing gear is a non-retractable, unsprung monowheel with a tailskid.
The SB-5 prototype first flew on 3 June 1959. A licence to build it went to Firma Eichelsdörfer at Bamberg, who produced more than 100 including all variants. The first three variants, SB-5a-c detailed below, differed chiefly in their forward fuselages and canopy shapes and the last (SB-5e) by having an extended span.
Airworthiness directives
Luftfahrt-Bundesamt, the national civil aviation authority of Germany, has issued two airworthiness directives concerning the structure of the tail section of this glider. Both related to issues with frame components towards the rear of the fuselage: the first, dated 30 January 1986, required an immediate inspection of frame 25 for cracking; the second, issued on 11 July 1991, required the gluing of frame 26 to be reinforced. The UK Air Accidents Investigation Branch cited these directives in its investigation of an accident in Cumbria, England, on 7 August 2019, when the tail section of a model SB-5e broke away in turbulent air conditions, causing the loss of the aircraft.
Operational history
In 2010, there were thirty seven SB-5s on the German civil register and one each on the Belgian and UK registers. Of these, eighteen were SB-5bs, twenty SB-5es and one a SB-5c.

Variants

SB-5a
Original version, with a short, tear drop style canopy proud of upper fuselage line. Braking parachute, no air brakes. Only one, crashed June 1961.
SB-5b
First production model. Lengthened forward fuselage with pilot in reclined seat under long canopy reaching forward almost to the nose and blended into fuselage line over wings. Airbrakes. Around 50 built.
SB-5c
Second production model. Shorter canopy not reaching nose, ground clearance raised by placing monowheel in short fairing rather than directly within fuselage. Some GRP in fuselage. About 10 built. First flown 1965.
SB-5d
SB-5e
16 m (52 ft 6 in) span to meet Club Class rules. Entered production 1974, with at least 20 built.
IPE SB-2
Between 1970 and 1980 two were built under license using local wood by IPE Aeronaves.
Aircraft on display
Auto und Technik Museum, Sinsheim, Germany - SB-5b Sperber D-5480.
Specifications (SB-5c)
(Data from Jane's All the World's Aircraft 1966/7)
General characteristics
Crew: One
Length: 6.6 m (21 ft 8 in)
Wingspan: 15.00 m (49 ft 3 in)
Wing area: 13.00 m2 (139.9 sq ft)
Aspect ratio: 17.3
Airfoil: NACA 633618
Empty weight: 220 kg (485 lb) equipped
Max takeoff weight: 325 kg (717 lb)
Performance
Maximum speed: 200 km/h (120 mph, 110 kn) smooth air
Stall speed: 60 km/h (37 mph, 32 kn)
Maximum glide ratio: best 32.5:1 at 77 km/h; 42 kn (48 mph)
Rate of sink: 0.63 m/s (124 ft/min) minimum at 66 km/h; 37 kn (41 mph)
Wing loading: 23.1 kg/m2 (4.7 lb/sq ft) maximum

SB-5b

Akaflieg Braunschweig SB-7 Nimbus

SB-7 Nimbus
Role - Standard class competition glider
National origin - West Germany
Manufacturer - Akaflieg Braunschweig
First flight - October 1962
Number built - about 4
Developed from - SB-6 Nixope

The Akaflieg Braunschweig SB-7 Nimbus is a Standard class glider designed and built in Germany in the 1960s. It was one of a series of mixed glass fibre and wood designs from the students of Akaflieg Braunschweig.
Design and development
The Akaflieg Braunschweig or Akademische Fliegergruppe Braunschweig (English: The Brunswick Academic Flying Group) is one of some fourteen German undergraduate 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 Nimbus was a development of the SB-6 Nixope. The main differences are the shorter span, 15 m rather than 18 m, and the T-tail of the Standard class Nimbus. Wing construction was simplified by the introduction of a 3.5 m (11 ft 6 in) long rectangular centre panel. Like its predecessor, the Nimbus was built from a mixture of wood and glass fibre. Its shoulder mounted wings are built around box spars with glass fibre flanges and covered with glass fibre laid over balsa. They have an Eppler profile, 2° of dihedral and a taper ratio of 0.49. Schempp-Hirth airbrakes are located at 75% chord. The tail unit is constructed in the same way as the wing and all surfaces are straight tapered. The narrow chord, all-moving tailplane is mounted on top of the fin.
The fuselage of the Nimbus is a glass fibre monocoque over balsa. It tapers gently from wing to tail; forward, the cockpit has a long, one piece canopy. The Nimbus has a retractable monowheel undercarriage, assisted by a tailskid.
The Nimbus first flew in October 1962. It performed very well, but the Eppler wing profile made it a challenge to fly. The recognition of this problem led to the SB-8 but also to a progressive series of modifications to the SB-7. The Eppler wing profile was replaced by one of Wortmann FX-61-163 form, the span increased to 17.0 m (55 ft 2 in), the tail and fuselage geometry revised. It was also given a reshaped, two piece canopy, improved airbrakes and a tail parachute.
Another SB-7 was built by Paul Kummer and Oscar Weisendanger in Switzerland which had yet another new wing of span of 16.52 m (54 ft 2.5 in), an aspect ratio of 20.85 and a different Eppler profile, 417 rather than the original 306. In addition the wing mounted airbrakes were replaced with a landing parachute. This version first flew 20 May 1967 and was followed by either one or two more aircraft more prototypes.
Operational history
Despite its newness and difficult handling, Rolf Kuntz flew the Nimbus into second place at the 1962 German National Championships, held at Freiburg im Breisgau. Because of its retractable undercarriage the 15 m span SB-7 had to compete in the Open, rather than Standard class at the 1963 World Gliding Championships, held at Junin in Argentina, flown again by Kuntz. He finished 17th in a field of 25.
It also competed in the German Nationals held at Roth in 1966, this time in the Standard class and flown by Eckhard Möllendorf.
The original Nimbus flew with the Akaflieg for 16 years. It was taken out of service in 1977 but was restored and reflown from 1982 until badly damaged in a landing accident in 1994. It was again restored, making its first flight for over 17 years on 1 November 2011.
One Nimbus remains on the German civil aircraft register in 2010.
Specifications (original)
(Data from Jane's All the World's Aircraft 1966/7)
General characteristics
Crew: One
Length: 7.00 m (23 ft 0 in)
Wingspan: 15.00 m (49 ft 3 in)
Height: 0.74 m (2 ft 5 in) over cockpit
Wing area: 11.85 m2 (127.6 sq ft)
Aspect ratio: 19
Airfoil: Eppler 306, thickness/chord 12%
Empty weight: 255 kg (562 lb) equipped
Max takeoff weight: 360 kg (794 lb)
Performance
Maximum speed: 254 km/h (158 mph, 137 kn) in smooth air
Maximum glide ratio: 37.5:1 at 90 km/h (56 mph; 49 kn)
Rate of sink: 0.67 m/s (132 ft/min) at 90 km/h (56 mph; 49 kn)
Wing loading: 30.0 kg/m2 (6.1 lb/sq ft) maximum

Akaflieg Braunschweig SB-8

SB-8
Role - Single seat experimental glider
National origin - West Germany
First flight - 1967
Number built - 2
Developed from - Akaflieg Braunschweig SB-7 Nimbus
Developed into - Akaflieg Braunschweig SB-10 Schirokko

The Akaflieg Braunschweig SB-8 is an experimental, single-seat, high performance glider built in Germany in the 1960s, constructed largely from glass fibre skin over built up balsa wood structure. Two were built; the second of which was later fitted with a high aspect ratio (30:1) wing, becoming the Akaflieg Braunschweig SB-9 Stratus.
Design and development
The Akaflieg Braunschweig or Akademische Fliegergruppe Braunschweig (English: The Brunswick Academic Flying Group) is one of fourteen German undergraduate student flying groups sponsored by their home technical university. Several have designed and built aircraft, often technically advanced and leading the development of gliders in particular. The Brunswick students had been exploring the use of GRP in a series of related gliders, beginning with the SB-6. From the SB-8 to the SB-10, wingspan and aspect ratio were progressively increased. The aspect ratio was increased from 23 to 36.6, resulting in aeroelastic problems.
SB-8
The SB-8 is similar to the SB-7, which also had an aspect ratio of 23. It performed well but had difficult handling characteristics, attributed to its Eppler aerofoil section. The SB-8 has an 18 m (59 ft 1 in) wingspan, a two-piece wing of Wortmann FX 62 profile with an unswept leading edge, a slightly tapered center section, and more strongly tapered outer sections. It is built around a box beam, with balsa ribs and a torsion shell of glass fibre laid over balsa. The wing is shoulder mounted at 1.5° dihedral, with Schempp-Hirth airbrakes at mid-chord midway along the center section and ailerons on the outer panels. Both SB-8 built have camber flaps on the inboard wing panel and ailerons which are coupled to the flaps (flaperons) on the outboard panels.
The fuselage of the SB-8 is built with a fibreglass skin, over a balsa shell, with balsa vertical frames and two pine plywood main formers in the region between the wings. The nose is pointed and slightly drooped, with a short, single piece, canopy just ahead of the wings, tapering gently aft to a straight tapered balsa/GRP T-tail unit. The tailplane carries a conventional single-piece elevator and the rudder is fabric covered. On the ground the SB-8 is supported by a retractable, unsprang monowheel undercarriage, assisted by a tail bumper.
The first flight was made from Brunswick airport on 25 April 1967; testing confirmed that the glass fibre structure was too flexible and at high speeds the SB-8 exhibited wing flutter, limiting its maximum permitted speed to 170 km/h (105.6 mph; 91.8 kn). The low wing loading also limited its smooth air cross country speed as there was no provision for ballast. Later, removable steel tubes filled with lead pellets were added to the wing roots of the SB-8 V1 to increase wing loading. A second aircraft, SB-8 V2, was therefore built with a stiffened, heavier wing and provision for water ballast, which addressed both aero-elasticity and wing loading problems, allowing the glider to fly safely, without flutter, at 200 km/h (124.3 mph; 108.0 kn).
SB-9 Stratus
The SB-8 V2 had shown that glass-fibre wings could be made stiff enough to avoid aeroelastic flutter problems and that the higher aspect ratio produced the expected improvement in glide angle. It was natural for the next Akaflieg Braunschweig design to have a wing of greater span, replacing the wing of the SB-8 V2 airframe with a four-panel wing of similar construction but 22 m (72 ft 2 in) span. At the time of its first flight in January 1969 the SB-9 had probably the greatest span of any glider then flying, though the 22 m (72 ft 2 in)-span Holighaus Nimbus 1 flew only three days later. The increase in aspect ratio over the SB-8 increased the measured best glide ratio from 40:1 to 46:1 and decreased the measured minimum sink rate from 0.61 m/s (120.08 ft/min) to 0.51 m/s (100.39 ft/min). The new wing took advantage of the flexibility of glass fibre to implement elastic flaps. The intention was to avoid the interruption to the wing profile at the hinge, particularly on the critical upper surface, and leakage through it by bending the upper surface instead. This method had been used earlier in the wooden-winged HKS-1 glider of 1953.
Operational history
Both SB-8s competed at the German National Championships of 1968, Wolfgang Beduhn finishing fifth in the V1 and Helmut Treiber seventh in the V2. The V2 went on to become the SB-9, but the V1 remained in regular use at Brunswick until 1989. It remained airworthy after that, though flown less often, and was still on the German Civil Aircraft register in 2010.
The SB-9 was used by the Akaflieg students in competitions between 1969 and 1971. It also gave them the opportunity to film and study the alarming motions of the wing when fluttering, recording their observations on film in slow motion and in the air. Two antisymmetric, odd, sine-like lateral displacement modes were observed at 90 km/h (55.9 mph; 48.6 kn). The fundamental mode was seen, at a frequency of 3.3 Hz but at 140 km/h (87.0 mph; 75.6 kn) the wing oscillated at 5.8 Hz in a second harmonic mode. During these largely vertical excursions, the wing also twisted and its overall motion excited vibrations in the rear fuselage and tail unit. The flutter problems were addressed by mass-balancing, the ailerons, and by a span reduction to 21 m (68 ft 11 in).
The career of the SB-9 ended in 1972, when it was decided to use its wing on the SB-10 two-seater, a new design with a very different fuselage and the span increased still further with an 8.7 m (28t ft 7 in) centre section.
Variants
Data from Sailplanes 1965-2000 unless excepted.
SB-8 V1
Original aircraft, empty weight of 260 kg (570 lb) and a maximum take-off weight of 365 kg (805 lb). Flutter restricted maximum permitted speed to 170 km/h (110 mph; 92 kn).
SB-8 V2
Stiffened wing, weights increased by 40 kg (88 lb). Provision for water ballast, maximum permitted speed increased to 200 km/h (120 mph; 110 kn).
SB-9 Stratus
The SB-8V2 was modified with a four-part wing of 22 m (72 ft 2 in) span, fitted with elastic flaps. SB-9 Stratus was first flown in January 1969. It is Empty weight, 325 kg (717 lb), maximum in flight weight, ballasted, 421 kg (928 lb). Flutter problems were tackled with a span reduction to 21 m (68 ft 11 in) and mass-balancing the ailerons.
Specifications (SB-8 V2 & SB-9)
General characteristics
Crew: 1
Length: 7.505 m (24 ft 7 in)
Wingspan: 18 m (59 ft 1 in)
SB-9: 22 m (72 ft 2 in) (reduced to 21 m (68 ft 11 in) later)
Wing area: 14.1 m2 (152 sq ft)
SB-9: 15.48 m2 (166.6 sq ft)
Aspect ratio: 23
SB-9: 31.3
Airfoil: root:Wortmann FX 62-K-153, mid:Wortmann FX 62-K-131, tip:Wortmann FX 60-126
Empty weight: 301 kg (664 lb)
SB-9: 325 kg (717 lb)
Gross weight: 403 kg (888 lb)
Max takeoff weight: 451 kg (994 lb)
SB-9: 421 kg (928 lb)
Performance
Never exceed speed: 200 km/h (120 mph, 110 kn)
Maximum glide ratio: 41.6 at 85 km/h (53 mph; 46 kn)
SB-9: 46 at 83 km/h; 52 mph (45 kn)
Rate of sink: 0.61 m/s (120 ft/min) at 88 km/h (55 mph; 48 kn) at 27.7 kg/m2 (5.7 lb/sq ft) and 385 kg (849 lb)
SB-9: 0.51 m/s (100 ft/min) at 80 km/h (50 mph; 43 kn) at 27.3 kg/m2 (5.6 lb/sq ft) and 414 kg (913 lb)
Wing loading: 28.6 kg/m2 (5.9 lb/sq ft)
SB-9: maximum wing loading 27.3 kg/m2 (5.6 lb/sq ft)

Akaflieg Braunschweig SB-10 Schirokko

SB-10 Schirokko
Role - Two-seat high performance sailplane
National origin - West Germany
Manufacturer - Akaflieg Braunschweig
First flight - 22 July 1972
Produced - no
Number built - 1

The Akaflieg Braunschweig SB-10 Schirokko is a German two-seat high performance sailplane designed and built by students of Brunswick University. The sailplane was not intended for production.
Design
The SB-10 is a cantilever shoulder-wing monoplane with a steel-tube structure fuselage and it used the wings from the earlier SB-9 Stratus. The two crew sit in tandem in an enclosed cockpit with a Plexiglas canopy, and it is fitted with dual instrumentation. The landing gear is a sprung retractable monowheel with a tail bumper. The wingtips are interchangeable and two types can be fitted to give a 26m or 29m span. The wing center section, its main spar and wing shells of 8m length were built using carbon fiber, a first in civil aircraft structure manufacturing.
Specifications (with 29m wing)
(Data from Jane's All the World's Aircraft 1973-74)
General characteristics
Crew: 2
Length: 10.36 m (33 ft 11.75 in)
Wingspan: 29.00 m (95 ft 1.75 in)
Height: 2.50 m (8 ft 2.5 in)
Wing area: 22.95 m2 (247 sq ft)
Aspect ratio: 36.6
Empty weight: 577 kg (1,272 lb)
Gross weight: 897 kg (1,977 lb)
Performance
Maximum speed: 200 km/h (124 mph, 108 kn)
Stall speed: 65 km/h (40 mph, 35 kn)
g limits: +5.3
Maximum glide ratio: 53
Rate of sink: 0.41 m/s (81 ft/min)

Akaflieg Braunschweig SB-11

SB-11
Role - Experimental single seat sailplane
National origin - Germany
Manufacturer - Akaflieg Braunschweig
First flight - 1978
Number built - 1

The Akaflieg Braunschweig SB-11 is an experimental, single seat, variable geometry sailplane designed by aeronautical students in Germany. It won the 15 m span class at the World Gliding Championships of 1978 but its advances over the best, more conventional, opposition were not sufficient to lead to widespread imitation.
Design and development
The Akaflieg Braunschweig or Akademische Fliegergruppe Braunschweig (English: The Brunswick 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 announcement, in 1975, of a new, unrestricted 15 m glider class led the Brunswick group to the design of the SB-11, a variable geometry aircraft.
A long-standing challenge for the designers of competition sailplanes were the conflicting requirements posed by the need to gain height in sometimes weak and narrow thermals, calling for low stalling speeds for small radius turns, and the need for rapid penetration of the cool, sinking air between thermals. In thermals, wings should ideally be of high camber and be lightly loaded; between thermals, low camber wings with high wing loading would fly faster. Large area, camber-changing flaps were one solution but vortexes generated at their extremities added significantly to the drag, decreasing climb rates. Akaflieg Brunswick decided to follow the example of the disappointing British Sigma by providing the SB-11 with Wortmann flaps along the whole of the trailing edge of the wing, including the ailerons. This avoided the flap-associated vortexes, though any increase in wing area, however implemented, will lower the aspect ratio and raise the induced drag caused by wingtip vortexes.
The SB-11 is almost entirely built of weight-saving CRP. In order to concentrate design effort on the wing, the Brunswick students blended together the front fuselage of the Schleicher ASW 20 with the rear fuselage and empennage of the Schempp-Hirth Janus. This gave the SB-11 a conventional fuselage, deeper forward of the shoulder wing, with a long, single piece, forward hinged canopy and a monowheel undercarriage under the wing. There is provision for water ballast. The rear fuselage is slender, with a T-tail with straight edged fin, rudder and swept, all moving tailplane.
The wings of the SB-11 have 2.3° of dihedral and are unswept. The inner 60% of span has constant chord. The outer panels, carrying the ailerons, are straight tapered with a taper ratio of 0.4. Manually driven full-span Fowler type Wortmann flaps emerge from the trailing edge between rollers, increasing the chord by 200 mm (7.9 in) over the untapered inner wing and by 80 mm (3.2 in) at the tip. Overall the flaps produce a 25% increase in wing area. Their trailing edges carry ailerons outboard and plain camber-changing flaps inboard. Mid-chord Schempp-Hirth airbrakes are placed at about mid span on the upper surface of the wing.
Operational history
The SB-11 first flew in 1978. The flaps worked well, with low operating loads and deploying "at the flick of a lever". It was entered into the 16th World Gliding Championships held at Châteauroux in France in July 1978, piloted by Helmut Reichmann. He won the 15 m class, followed by an ASW-20 not far behind.
The SB-11 provided a useful test of the advantages of variable geometry gliders. Thoroughly examined at the Competition and in later tests, it outperformed the other 15 m class gliders of its day in the climb but, crucially, not by much. Its stalling speeds and turn radius was smaller than that of the ASW 20, good for weak thermals, but was perhaps rather poorer than the ASW in the fast glide. Whilst Reichmann was pleased with the SB-11 at the meeting, saying it was the best aircraft there, he later noted that cross-country pilots had plenty to do already and that finding strong lift was more important than exploiting weak thermals. Experience with the SB-11 and with later variable geometry gliders from the Akafliegs of Munich, Darmstadt and Stuttgart (the Mü27, D-40 and FS-29 respectively) showed that, whilst there were performance gains, these were not enough to compensate for the extra expense, complexity and pilot workload that accompanied them; variable geometry did not, in the end, prove a useful way forward.
Specifications
(Data from Sailplanes 1965-2000)
General characteristics
Crew: 1
Length: 7.405 m (24 ft 4 in)
Wingspan: 15.00 m (49 ft 3 in)
Wing area: 10.56 m2 (113.7 sq ft) with flaps retracted; 13.2 m2 (142 sq ft) flaps extended
Aspect ratio: 21.3 flaps retracted; 17.0 flaps extended
Airfoil: Wortmann HQ - 144 - 39 W3
Empty weight: 270 kg (595 lb)
Gross weight: 340 kg (750 lb) (maximum with 105 kg (231 lb) ballast 470 kg (1,036 lb))
Performance
Maximum speed: 265 km/h (165 mph, 143 kn) flaps retracted; 140 kmh (87 mph; 76 kn) flaps extended
Stall speed: 75 km/h (47 mph, 40 kn) flaps retracted; 58 kmh (36 mph; 31 kn) flaps extended
Maximum glide ratio: best 1:41 at 104 kmh (65 mph; 56 kn) flaps retracted; 1:36 at 85 kmh (53 mph; 46 kn) flaps extended
Rate of sink: 0.67 m/s (132 ft/min) minimum; flaps retracted, this is at 104 kmh (65 mph; 56 kn) with flaps extended at 85 kmh (53 mph; 46 kn)
Wing loading: 44.5 kg/m2 (9.1 lb/sq ft) at 470 kg (1,036 lb) with flaps retracted; 35.06 kg/m³ (7.2 lb/sq ft) flaps extended

Akaflieg Braunschweig SB-12

SB-12
Role - Experimental Standard Class sailplane
National origin - Germany
Manufacturer - Akaflieg Braunschweig
First flight - 9 April 1980
Number built - 1

The Akaflieg Braunschweig SB-12 is a single seat, Standard Class sailplane designed around 1980 by German technical university students to test out a new wing profile from the German Aerospace Centre. It was not intended for production, but the sole SB-12 remains active in 2010.
Design and development
The Akaflieg Braunschweig or Akademische Fliegergruppe Braunschweig (English: The Brunswick 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 Brunswick students began the design of the Standard Class SB-12 in mid-1979 and the first flight was made on 9 April 1980. It was not intended for production but to test out a new wing aerodynamic profile designed by the German Aerospace Centre (DFVLR) for high cruising performance. The wing of the SB-12 has single, I-section spars, with carbon fibre flanges and GRP webs. The skins are carbon fibre and polymeric foam. The wings are mounted at mid-fuselage at an incidence of 0.5° and with 3° of dihedral. They carry GRP ailerons and wide span airbrakes but no spoiler or flaps.
The fuselage is a GRP monocoque with a front hinged canopy over the single seat cockpit and a tank for 150 kg (331 lb) of water ballast. The SB-12 has a T-tail, with tailplane and elevators set on top of a straight edged, only slightly tapered fin and rudder. The fixed surfaces are formed from GRP and plastic foam sandwich, the moving surfaces using only GRP. Its undercarriage has a retractable, unsprung monowheel, fitted with an internal drum brake, with a fixed, partly recessed tailwheel.
Operational history
The sole SB-12, registration D-1225 and wearing HQ, for its airfoil, on the tail remained with Akaflieg Braunschweig until they sold it in 1989. About ten years later it was sold to an owner in the German Alps and in 2007 sold again and returned to Brunswick. It remained on the German register in 2010.
Specifications
(Data from Jane's All the World's Aircraft 1981/2 / All performance figures estimated)
General characteristics
Crew: 1
Length: 6.40 m (21 ft 0 in)
Wingspan: 15.00 m (49 ft 3 in)
Height: 1.40 m (4 ft 7 in)
Wing area: 10.02 m2 (107.9 sq ft)
Aspect ratio: 22.5
Airfoil: DFVLR HQ 014, thickness-to-chord ratio 18.43%
Empty weight: 220 kg (485 lb)
Max takeoff weight: 450 kg (992 lb)
Performance
Maximum speed: 250 km/h (160 mph, 130 kn) smooth air
Maximum glide ratio: 42, best at 98 km/h (61 mph; 53 kn) and an all-up weight of 310 kg (683 lb)
Rate of sink: 0.6 m/s (120 ft/min) minimum at 78 km/h (48.5 mph; 42 kn) and at an all-up weight of 310 kg (683 lb)
Wing loading: 44.9 kg/m2 (9.2 lb/sq ft)

Akaflieg Braunschweig SB-13 Arcus

SB13 Arcus
Role - Single seat experimental glider
National origin - Germany
First flight - 18 March 1988
Retired - 2000
Number built - 1

The Akaflieg Braunschweig SB-13 Arcus was an experimental tailless, single-seat, Standard Class glider designed and built in Germany in the early 1990s. Though it performed as well as its conventional contemporaries, it did not offer sufficiently improved performance to compensate for its difficult handling characteristics.
Design and development
The Akaflieg Braunschweig or Akademische Fliegergruppe Braunschweig (English: The Brunswick Academic Flying Group) is one of some fourteen German undergraduate 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. In 1982 when the SB-13 design was first discussed no new tailless glider had been built for thirty years, during which time glass reinforced plastic materials had replaced wood in glider construction and much learned about laminar flow wings; it was hoped that tailless designs would be lighter, simpler and cheaper.
Work on the SB-13 Arcus, named after the cloud formation, began in 1982. Because of the novelty of the layout, a one-third scale model of the early design was built and flown, revealing several serious problems. Strong flutter was experienced even at modest speed, and the aircraft was susceptible to the centre of gravity (c.g.) position. It stalled readily when this was too far aft. Recovery from the spin that followed was difficult. With the centre of gravity too far forward, a rapid longitudinal "pecking" oscillation set in, which was difficult to control due to its short duration. A major redesign involving extensive computer analysis led to a new wing with carbon fibre stiffening on the main spar; in addition, both it and the wing plan were made curved. The new structure resisted flutter until 270 km/h (168 mph) was reached.
The full-scale SB-13 finally flew in 1988. Its 15 m (49.2 ft) wing was straight-edged, with three slightly tapered sections of increasing sweep. The two inner panels occupied less than 1.9 m (6.2 ft) of the span, and the outer section leading edge was swept at about 17°. All had a dihedral of 4°. At its tips, where the chord was 600 mm (24 in), the wing turned upwards into 1,250 mm (49 in) tall, slightly swept winglets, which carried rudders. Elevons occupied much of the outer panel trailing edge and, further inboard, mid-chord mounted airbrakes were fitted. The fuselage, onto which the wings were mounted between low and mid position, was a short pod with its nose a little ahead of the centre section leading edge, extending aft about as far as the trailing horizontal edge of the wing at its tip. The pilot reclined under a long, bulged, single piece canopy, which was side-hinged to starboard. The cockpit reached beyond the wing both forward and aft, with the main spar passing through it under the pilot's knees.
Despite the modifications made to remove the handling problems predicted by the model, the full-scale SB-13 still "pecked" and spun readily; when the standard spin correction procedure was applied, a new spin started in the opposite direction. Over the next few years, several aerodynamic devices were tried, some of which at least improved the behaviour of the Arcus; one longer-lasting outcome from the project was the start of an investigation into whole aircraft rescue parachutes. The competition performance of the Arcus was on a par with that of the other 15 m gliders of the time, but it did not offer a significant improvement over them, which might have justified even more effort to improve the handling.
Operational history
The sole SB-13 was flown, modified and studied from 1988 to 2000 when it was damaged and set aside in favour of newer aircraft. In 2007 it went to the Deutsches Museum, Munich for exhibition.
Aircraft on display
SB-13 D-1113 is on display in the Deutsches Museum Flugwerft Schleissheim.
Specifications
{Data from Sailplanes 1965-2000 (characteristics) / Akaflieg Braunschweig website (performance) / Jane's All the World's Aircraft 1988-89 (performance)}
General characteristics
Crew: 1
Length: 3.02 m (9 ft 11 in) fuselage pod
Wingspan: 15.0 m (49 ft 3 in)
Height: 1.96 m (6 ft 5 in)
Wing area: 11.64 m2 (125.3 sq ft)
Aspect ratio: 19.4
Airfoil: HQ 34N/14.83 at root, HQ 36N/15.12 at tip. Winglet Wortmann FX 7-L-150/K30
Empty weight: 258 kg (569 lb)
Max takeoff weight: 418 kg (922 lb) with water ballast
Performance
Stall speed: 70 km/h (43 mph, 38 kn)
Never exceed speed: 210 km/h (130 mph, 110 kn) / 170 km/h (110 mph; 92 kn) on aero-tow
150 km/h (93 mph; 81 kn) on winch launch
g limits: +5.3, -2.65
Maximum glide ratio: 42:1 at 107 km/h (67 mph; 58 kn)
Rate of sink: 0.57 m/s (112 ft/min) minimum, at 85 km/h (53 mph; 46 kn)
Wing loading: 36.1 kg/m2 (7.4 lb/sq ft) maximum

SB-13 at the Deutsches Museum Flugwerft Schleissheim

Akaflieg Braunschweig SB-14

SB 14
Role - single seat sailplane
National origin - Germany
Manufacturer - Akaflieg Braunschweig
First flight - 17 January 2003
Number built - 1

The Akaflieg Braunschweig SB 14 is an 18 m (59 ft) Open-class sailplane designed and built in Germany in the early 2000s.
Design and development
The SB 14 was designed to minimalist principles, reducing wetted area and use of high speed aerofil sections in a high aspect-ratio wing. As an economy measure, the tail unit of the Schleicher ASH 26 was utilised. To improve performance of the wing in a wide range of conditions, the wing-tips have swept wing-lets, as well as turbulators forward of the flaps on the undersurface of the wings.
The SB 14 is a shoulder-wing sailplane constructed from carbon-fibre composite materials. The wings are of very high aspect-ratio and incorporate full span flaperons with slots for when the flaps are extended. The fuselage follows contemporary design practice with a cockpit pod and slender rear fuselage terminating in a T-tail. The cross section of the fuselage has been minimised throughout, reducing wetted area and therefore minimising drag.
Control is through conventional elevator and rudder with full span slotted flaperons on the wings and Schempp-Hirth airbrakes on the upper surfaces at about 1/3 span. The undercarriage is a conventional retractable mono-wheel main undercarriage with a steel tipped rubber block tail-skid under the fin.
Flight testing, from 17 January 2003, revealed very promising performance, optimised with various aero-dynamic refinements.
Specifications (SB-14 prelim flight testing performance figures)
General characteristics
Crew: 1
Capacity: payload (pilot + equipmqnt) 96 kg (212 lb); Water ballast 160 kg (350 lb)
Length: 6.95 m (22 ft 10 in)
Wingspan: 18.00 m (59 ft 1 in)
Height: 1.23 m (4 ft 0 in)
Wing area: 10.84 m2 (116.7 sq ft)
Aspect ratio: 29.89
Airfoil: root: CA2-134 / 15V2 ; tip: CAJ1-134 / 18
Empty weight: 285 kg (628 lb)
Max takeoff weight: 541 kg (1,193 lb)
Performance
Never exceed speed: 272 km/h (169 mph, 147 kn)
Minimum speed: 70 km/h (43 mph; 38 kn)
Maximum glide ratio: 50:1 (approx)
Rate of sink: 0.5 m/s (98 ft/min)
Wing loading: 33.9 kg/m2 (6.9 lb/sq ft) to 50 kg/m2 (10 lb/sq ft)

The SB-14 at ILA Berlin 2008