Jane's Encyclopedia of Aviation

Schempp-Hirth Nimbus 2, HS-7 Mini-Nimbus and Janus (Germany)

   Single-seat Open Class sailplane; single-seat 15-metre Contest Class sailplane; and tandem two-seat high-performance training sailplane respectively.

M.Hardy. Gliders & Sailplanes of the world

Schempp-Hirth Cirrus

  This high performance single-seater is Schempp-Hirth KG's first sailplane of glassfibre construction, and was designed and test flown by Dipl-Ing Klaus Holighaus, who became a 50% shareholder in Schempp-Hirth in 1970 and five years later became co-owner of the reorganised Glasflugel firm. To achieve good low speed and climb characteristics the new thick Wortmann FX 66 series wing section was used, without any flaps, the stalling characteristics being better and weight saved by comparison with a thinner wing of similar span and aspect ratio with flaps, the slight disadvantage this thick section has compared with the thinner wings being over come by provision for water ballast, up to 216lb of which can be carried. The prototype Cirrus made its first flight in January 1967 with an all-moving V-tail unit, but the second prototype and production aircraft had a conventional tail with the tailplane mounted part-way up the fin. A Cirrus flown by Harro Wodl of Austria was first in the Open Class in the 1968 World Championships at Leszno in Poland. A total of 120 Cirrus sailplanes were built by Schempp-Hirth before production ended late in 1971, but manufacture of the type has been continued since early in 1972 at Vrsac in Yugoslavia by VTC - Vazduhoplovno Technicki Centar - Vrsac; VTC had built about 60 by early 1975 under licence and production continues. The cantilever mid wings have an all-glassfibre box spar and the wing shell is of glassfibre/foam sandwich construction; the hinged ailerons are of glassfibre/balsa sandwich, and the Schempp-Hirth air brakes on both upper and lower wing surfaces are of aluminium alloy, a tail braking parachute also being fitted. The fuselage is a glassfibre shell, 1.5mm thick, stiffened with foam rings, and secured with resin. The cantilever tail unit is a glassfibre/foam sandwich structure. Landing gear consists of a manually-retractable monowheel with an annular rubber-sprung shock absorber and a drum brake. The pilot sits on a semi-reclining adjustable seat under a one-piece Plexiglas canopy.


Span: 58 ft 2 1/2 in
Length: 23 ft 7 1/4 in
Height: 5 ft 0 in
Wing area: 135.6 sqft
Aspect ratio: 25.0
Empty weight: 573 lb
Max weight: 882 lb
Max speed: 137 mph (in smooth air)
Max aero-tow speed: 87 mph
Min sinking speed: 1.64 ft/sec at 45 mph
Best glide ratio: 44:1 at 53 mph



Schempp-Hirth Standard Cirrus

  Designed by Dipl-Ing Klaus Holighaus, this high performance single-seater is, as its name implies, a Standard Class version of the Cirrus but with some important differences, in particular a T-tail, a new fuselage with a long flush-fitting one-piece Plexiglas canopy hinged at the starboard side, and a 15m span wing of different Wortmann aerofoil section, with the same root thickness/chord ratio of 19.6% as on the Cirrus and also without flaps. The prototype Standard Cirrus first flew in March 1969 and production began in the summer of that year. The type proved to have very docile and pleasant handling qualities and soon made its mark in competition flying, winning the Standard Class at the International Soaring Competition at Hahnweide in 1969 and going on to win many national gliding contests. By April 1977, when production by Schempp-Hirth ended, a total of 700 Standard Cirruses had been built, including 200 built under licence by Grob Flugzeugbau, makers of the Astir series of sailplanes, between 1972 and July 1975. Manufacture of the type is being continued under licence from Schempp-Hirth by the French firm Lanaverre Industrie, formed at Bordeaux in 1977 by Morin SA and the boat-building concern Yachting France; 30 had been completed by 1 January 1979 as the Lanaverre Standard Cirrus, also known as the SCAP Cirrus 78L. VTC of Yugoslavia had also built 14 Standard Cirrus 75-VTCs by early 1979. The Standard Cirrus 75 was an improved variant produced by Schempp-Hirth in 1975 which had enlarged fairings at the wing roots, increased area air brakes, a modified nose similar to that of the Nimbus 2, jettison valves for the wing water ballast tanks repositioned to behind the monowheel, and a new type of easy-to-rig tailplane fitting. The cantilever mid wings and the ailerons are glassfibre/foam sandwich structures, and there are Schempp-Hirth glassfibre air brakes in the wing upper surfaces; unlike the Cirrus, there are no lower surface air brakes. The fuselage is a glassfibre shell, 1.5mm thick, stiffened with bonded-in foam rings, and the T-tail unit is of glassfibre/foam sandwich, the tailplane being an all-moving surface. The standard landing gear is a manually-retractable monowheel, but a non-retractable faired monowheel is optional for the customer; in both cases there is a drum brake. The pilot sits in a semi-reclining seat and has adjustable rudder pedals.


Data: Standard Cirrus 75
Span: 49 ft 2 1/2 in
Length: 20 ft 9 3/4 in
Height: 4 ft 4 3/4 in
Wing area: 107.6 sqft
Aspect ratio: 22.5
Empty weight: 474 lb
Max weight: 860 lb
Max speed: 137 mph
Max aero-tow speed: 93 mph
Min sinking speed: 1.87 ft/sec at 44 mph
Best glide ratio: 38.5:1 at 56 mph



Schempp-Hirth Nimbus 2

  The HS-3 Nimbus high performance single-seater was designed and built in his spare time by Dipl-Ing Klaus Holighaus, with the aid of Schempp-Hirth, of which he became a 50% shareholder in 1970. It had the same fuselage as the Open Class Cirrus married to a new high-set three-piece wing of 22m (72ft 2 1/2 in) span and the high aspect ratio of 30.6; the tail unit was similar to that of the Cirrus. The prototype first flew in January 1969 and the next year a Nimbus flown by George Moffat of the USA won the Open Class in the World Gliding Championships at Marfa, Texas. The HS-3 Nimbus was of glassfibre/foam sandwich construction, the fuselage having a steel tube frame for the attachment of wings and landing gear, and the manually-retracted monowheel had a drum brake. No air brakes were fitted, and the pilot sat under a long two-piece canopy. The Nimbus had an exceptionally high performance, with a best glide ratio of 51:1 at 56mph and a minimum sinking speed of only 1.44ft/sec, and this performance would ensure its sales prospects. The Nimbus 2 is the production version, differing from the HS-3 in having the same fuselage as the Standard Cirrus married to a wing of shorter span (20.3m) and built in four sections to limit weight and dimensions for ease of rigging, storage and trailer transport. The glassfibre/foam sandwich wing structure was stiffened to eliminate the bending experienced with the earlier Nimbus wing, and glassfibre Schempp-Hirth air brakes are fitted in the upper surfaces; there is also a tail braking parachute. The ailerons and interconnected flaps are glassfibre shells, the flap settings ranging from -8° for high speed flight to +6° for soaring in thermals and 20° for landing; the flaps of the earlier Nimbus drooped to 90° for landing. Up to 353lb of water ballast can be carried. The glassfibre fuselage shell is stiffened with bonded-in foam bulkheads and there is a central tubular steel framework for attaching the wings and landing gear. The Nimbus 2 also differs from the earlier version in having a glassfibre/foam sandwich T-tail very similar to that of the Standard Cirrus; the first 132 Nimbus 2s have an all-moving tailplane, but 133rd and later aircraft known as the Nimbus 2B have a fixed incidence T-tailplane and elevator. The retractable rubber-sprung monowheel has a drum brake. The pilot sits in a semi-reclining seat under a long flush-fitting hinged canopy. The Nimbus 2C has a higher gross weight, is fitted with new brake type flaps instead of upper surface air brakes, and is available to customers with wings and tailplane built of carbon-fibre as an alternative to glassfibre construction; with the former up to 550lb of water ballast can be carried.
  Design work on the Nimbus 2 began in January 1970 and the prototype, construction of which began in April that year, first flew in April 1971. By 1 January 1979 a total of 185 Nimbus 2s, 2Bs and 2Cs had been delivered, and the type has an outstanding competition record. It has twice won the Open Class in World Championships, in 1972 at Vrsac, Yugoslavia, flown by Goran Ax of Sweden and in 1974 at Waikerie, Australia, flown by George Moffat of the USA; in the 1976 World Championships in Finland, Nimbus 2s took no less than 14 of the first 25 places. On 15 February 1977 a Nimbus 2 flown by R.J. Rowe of Australia set a speed record of 83.264mph over a 750km course, and a similar record over 500km was set up by Edward Pearson of Rhodesia in another Nimbus 2 on 27 November 1976. The world distance record to a goal, for single-seaters, was set up by a group of three Nimbus 2s which covered 779.36 miles in New Zealand on 14 January 1978. The Nimbus 2CS that won the 1980 German National championships was modified to have extra wing panels to increase the span to 23.5m (77ft 0in). This preceded the Nimbus 3 which has a four-piece carbon-fibre wing of 22.9m span, and which was first flown in prototype form on 21 February 1981 by its designer Klaus Holighaus. The Nimbus 3 makes extensive use of carbon-fibre in its structure, only the forward fuselage being of glassfibre. The three-part ailerons droop in conjunction with the flaps, and over 80 gallons of water ballast can be carried. The Nimbus 3 is probably the first sailplane to achieve a glide angle of better than 1 in 50, a figure of 55:1 being claimed, and Mk 3s took the first three Open Class places in the 1981 World Gliding Championships at Paderborn, West Germany.


Data: Nimbus 2C with carbon-fibre wings
Span: 66 ft 7 1/4 in
Length: 24 ft 0 1/2 in
Height: 4 ft 9 in
Wing area: 155.0 sq ft
Aspect ratio: 28.62
Empty weight: 694 lb
Max weight: 1,433 lb
Max speed: 168 mph (in smooth air)
Max aero-tow speed: 99 mph
Min sinking speed: 1.5 ft/sec at 50 mph
Best glide ratio: 49:1 at 65 mph



Schempp-Hirth Nimbus 2M

  The Nimbus 2's outstanding performance not surprisingly led to thoughts of a powered version which, by virtue of its engine, could be self-launched. The Nimbus 2M, or Motor Nimbus, was developed under the direction of Dipl-Ing Klaus Holighaus and is fitted with a 50hp Hirth two-cylinder two-stroke engine that was originally produced for snowmobile racing in Canada. This drives a two-bladed fixed-pitch wooden propeller and is completely retractable, being lowered when stopped behind closed doors in the centre fuselage, the propeller being stopped so as to lie on the fuselage centreline. The powerplant is raised and lowered electrically, using the motor and rack-and-pinion gearing from a Bosch car sun roof installation, and since the engine weight is less than that of the water ballast carried by the unpowered Nimbus 2, its effect on performance when retracted is very slight. Up to 88lb of fuel can be carried in wing tanks and the take-off run with engine on is 1,310ft; rate of climb is 395ft/min and the range is 310 miles. The prototype Nimbus 2M first flew in June 1974, and made its debut at the First International Motor Glider Competition at Burg Feuerstein, West Germany, that same month. Apart from the engine installation, the Nimbus 2M is the same as the unpowered Nimbus 2.


Span: 66 ft 7 1/4 in
Length: 24 ft 0 1/2 in
Height: 4 ft 9 in
Wing area: 155.0 sqft
Aspect ratio: 28.62
Empty weight: 970 lb
Max weight: 1,279 lb
Max speed: 155 mph
Min sinking speed: 1.8 ft/sec at 53 mph
Best glide ratio: 47:1 at 62 mph



Schempp-Hirth Mini-Nimbus

  The Nimbus 2's exceptional performance had made it a leading contender in Open Class competition flying, in which it had twice won the World championships, and so there were obvious possibilities in a Standard Class version of this type with a shorter 15m span wing with camber-changing trailing edge flaps/air brakes and designed to meet the new FAI regulations for Standard Class 15-metre sailplanes. This was the HS-7 Mini-Nimbus, designed by Dipl-Ing Klaus Holighaus, which first flew in prototype form on 18 September 1976, and a total of 200 had been ordered by February 1977; altogether 155 Mini-Nimbuses of all versions had been delivered by the beginning of 1980. As with the Nimbus 2, the T-tailplane was an all-moving surface on initial production aircraft, but from March 1978 a fixed-incidence tailplane was offered as an option for customers, the type being known as the Mini-Nimbus B with this tailplane. The Mini-Nimbus C is offered with either carbon-fibre wings and tailplane or those of glassfibre construction and the same new features as on the Nimbus 2C. Of the same glassfibre/foam sandwich construction as the Nimbus 2, the cantilever mid wings have flaps that incorporate the wing root fairings and glassfibre air brakes in the wing upper surface immediately ahead of them. The flaps can be selected to five positions between -7° and +10°, and when they are lowered the trim lever operates the all-moving tailplane at the same time so as to give an automatic flap/trim system. Up to 265lb of water ballast can be carried, or 419lb in the carbon-fibre-winged Mini-Nimbus C. The glassfibre fuselage shell is stiffened with bonded foam rings and has a central tubular steel framework like that of the Nimbus 2; the fin is integral with the fuselage and the tailplane is of glassfibre/foam sandwich. Landing gear consists of a manually-retractable rubber-sprung monowheel with a drum brake. The pilot sits under a large one-piece flush-fitting canopy in a semi-reclining position.


Data: Mini-Nimbus C with carbon-fibre wings
Span: 49 ft 2 1/2 in
Length: 21 ft 0 1/2 in
Height: 4 ft 4 in
Wing area: 106.1 sqft
Aspect ratio: 23.0
Empty weight: 474 lb
Max weight: 1,102 lb
Max speed: 155 mph
Min sinking speed: 1.74 ft/sec at 48.5 mph
Best glide ratio: 42:1 at 65 mph



Schempp-Hirth Janus

  Although there are many single-seat sailplanes of glassfibre construction few two-seaters so far have been built of this material, the Janus high performance trainer being among the first of them. Design work on this type was begun by Dipl-Ing Klaus Holighaus in 1969, was continued from early 1972 onwards and the prototype first flew in May 1974. Production began with the second aircraft, incorporating several improvements, in January 1975 and 100 examples of all versions of the Janus had been delivered by early 1980 plus three motorised Janus CMs. The Janus B became available to customers in March 1978, this having a fixed-incidence tailplane instead of the all-moving type previously fitted. The Janus has set several speed and distance records for two-seaters, including a 100km triangular closed circuit speed of 88.8mph in Switzerland flown by Klaus Holighaus and U.Plarre on 15 August 1974, a women's goal and return flight record of 339 miles in Italy in April 1976, flown by Adele Orsi and M. Monti, and further speed records over 100km, 300km and 500km triangular closed circuits in South Africa in November 1977. The Janus has a glassfibre monocoque fuselage with bonded-in foam bulkheads, and this is similar to the Nimbus 2's but the cockpit section is lengthened to accommodate the two pilots in tandem with dual controls under a hinged one-piece canopy. Landing gear consists of a non-retractable monowheel with a drum brake, and a nosewheel; there is also a bumper under the rear fuselage. The two-piece cantilever mid wings have 2° forward sweep on the leading edge, and are of glassfibre/foam sandwich construction, with glassfibre monocoque ailerons, flaps and Schempp-Hirth air brakes in the wing upper surfaces; the camber-changing flaps are operated between +12° and -7°. The tailplane is also of glassfibre/foam sandwich construction. The Janus C has carbon-fibre wings of 20m span and a carbon-fibre tailplane.
  A French development of the Janus is the SCAP Lanaverre SL-2 all-plastics sailplane created by SCAP-Societede Commercialisation Aeronautique du Plessis, SaRL and Lanaverre Industries, the latter building the Standard Cirrus under licence from Schempp-Hirth. First flown on 15 October 1977, the SL-2 differs from the Janus chiefly in having provision for 30.8 Imp gallons (140 litres) of water ballast in the wings and a fixed tailplane with elevators instead of a one-piece all-moving tailplane; a more comfortable cockpit for the two pilots is provided, with provision for back-type parachutes.
  The Janus M prototype, D-KIBO, first flew in 1978 and is a motorised version with a 55hp Hirth O-28 engine mounted on a pylon aft of the cockpit end retracting into the fuselage.


Data: Janus
Span: 59 ft 8 1/2 in
Length: 28 ft 3 1/4 in
Height: 4 ft 9 in
Wing area: 178.5 sqft
Aspect ratio: 19.97
Empty weight: 838 lb
Max weight: 1,366 lb
Max speed: 136 mph (in smooth air)
Max aero-tow speed: 105 mph
Min sinking speed: 2.30 ft/sec at 56 mph
Best glide ratio: 39.5:1 at 68.5 mph



Schempp-Hirth Ventus

  The Ventus high performance single-seater (its name is the Latin for 'wind') is the first of a new generation of racing and competition 15m Class sailplanes featuring carbon-fibre in their structures; the mid-set wings are specially designed to take full advantage of this material's lightness and extra stiffness. A new wing section, thinner and more laminar than previous Wortmann profiles, has been developed for the Ventus by Professor F. X. Wortmann, physicist Dieter Althaus and Dipl-Ing Klaus Holighaus, this being specially designed for carbon-fibre construction and giving better performance throughout the entire speed range. A special characteristic of this new section is that at low-drag speeds, stall warning buffeting occurs when the angle of attack must increase over 10° before the stall itself actually occurs, this giving a previously unknown safety margin in narrow thermals, in ridge or mountain flying and in landing. The wing and its skin are made entirely of carbon-fibre, which gives increased torsional stiffness and reduces by over two-thirds the negative tip twist experienced with thin glassfibre wings, and the resulting lift penalties; the wing skin is made of specially developed extra-fine-weave carbon cloth, and has high stiffness to maintain the wing profile. The same new air brake/flap system as on the Nimbus 2C is featured, the air brakes being behind the 70% chord line outside the wing's laminar flow area, and this system gives an unusually short and slow landing. The two-piece ailerons feature Grob elastic flap-type joints on the lower wing surfaces to make the aileron/wing joint gapless and reduce drag, while enabling the upper surface gap to be kept very small. Tail surfaces are similar to those of the Nimbus, with a fixed-incidence tailplane and elevator.
  There are two fuselage sizes, the normal version (the Ventus B) being big enough for pilots from 5ft 9in to 6ft 5in tall, this fuselage being 24 3/8 in wide, 32 3/4in high and 21ft 4 3/4in long. The smaller fuselage (the Ventus A) is designed so that pilots up to 5ft 9in tall will not feel 'lost' in a cockpit designed to accommodate six-footers, and is 21 1/4 in wide x 29 1/2 in high x 20ft 9 1/2 in long; its smaller size results in a slight performance bonus. In both versions the pilot sits under a one-piece sideways-hinging cockpit canopy which is easily jettisonable; the canopy frame is of carbon-fibre and there is provision for a variety of instrumentation. Both fuselage sizes have a steel mid-fuselage frame on which is mounted the retractable monowheel, the flap and aileron drives and the wing lift-pin sockets; this frame takes the stresses from the landing gear directly through to the wings, and there is also a tail bumper fairing under the fin. The rudder sizes are slightly different for each fuselage size, and there is provision for over 330lb of water ballast in integral fuselage tanks. The prototype Ventus first flew on 3 May 1980, and a one-off sailplane known as the Lentus, which consists of a Ventus A fuselage fitted with Nimbus C wings, is used for performance comparison trials with the Ventus.


Span: 49 ft 2 1/2 in
Length: Ventus A 20 ft 9 1/2 in
   Ventus B 21 ft 4 3/4 in
Wing area: 102.4 sqft
Aspect ratio: 23.7
Empty weight: Ventus A 474 lb
   Ventus B 486 lb
Max weight: Ventus A and B 949 lb
Max speed: 155 mph
Min sinking speed: 2.17 ft/sec at 9.2 lb/sq ft wing loading
Best glide ratio: 44:1 at 74.6 mph



Akaflieg Berlin B 12

  Designed and built by the Akaflieg, or Akademische Fliegergruppe of Berlin University, the B 12 tandem high performance two-seater features the wings of a Schempp-Hirth Janus married to a new fuselage and tail unit which, like the wings, are also of glassfibre-reinforced plastic construction. Design work on the B 12 began in October 1973 and the prototype first flew on 25 July 1977; like the Janus the B 12 is a shoulder-wing monoplane wth Wortmann wing sections and a sweep forward of 2° 18' on the leading edge. The wings are of glassfibre foam sandwich construction, with glassfibre monocoque ailerons, flaps and Schempp-Hirth air brakes on the upper surfaces. Whereas the Janus has a T-tail, the B 12's tailplane is set low on a taller fin; the unsprung monowheel retracts rearwards and has a drum brake, whereas that of the Janus is fixed and the latter has a nosewheel unlike the B 12 and a rear fuselage bumper, a similar bumper also being a feature of the B 12.


Data: B 12
Span: 59 ft 8 1/2 in
Length: 28 ft 6 1/2 in
Height: 6 ft 6 in
Wing area: 178.5 sqft
Aspect ratio: 20.0
Empty weight: 976 lb
Max weight: 1,366 lb
Max speed: 155 mph
Max aero-tow speed: 93 mph
Min sinking speed: 1.97 ft/sec at 45.5 mph
Best glide ratio: 42:1 at 65 mph