Schempp-Hirth Nimbus-4
Encyclopedia
The Schempp-Hirth Nimbus-4 is a family of high-performance FAI Open Class gliders
designed by Klaus Holighaus
and manufactured by Schempp-Hirth Flugzeugbau GmbH in Kirchheim
, Germany
. The Nimbus-4 first flew in 1990.
and Nimbus-3. In total , 44 single-seat and 100 two-seat models had been produced. The wing has a multi-tapered planform
and the wingspan
was increased to 26.5 metres. The aspect ratio
is 38.8. The fuselage was also lengthened, and a larger rudder was fitted.
The manufacturer claims this glider has a glide ratio of better than 60:1 at a best glide airspeed of 110km/h (59 knots), meaning it can glide over 60 kilometres on course for every 1000 metres of altitude lost in still air.
There is a two seat version, the 4D, and motor glider
versions with either turbo engines (designation T) or self-launching engines (designation M).
(with fixed horizontal stabilizer and two-piece elevator
). The manufacturing process uses a hand lay-up of composite material plies and epoxy resins.
The wing's 26.5-meter (87-foot) span consists of three sections per side, consisting of a wing tip
, outboard section, and inboard section. The inboard sections mate at the fuselage and the outer wing sections mate with the inboard sections approximately 12.6 feet outboard of the fuselage root chord. The wing shells are a carbon fiber
/foam core sandwich construction with one main spar constructed of a glass fiber/foam core shear web and carbon fiber spar
flanges. A single-vane flap
spans the entire inboard wing section. Three sections of ailerons (that is, inboard, center, and outboard) span the outboard wing section with a fourth aileron, used to minimize the effects of adverse yaw, attached to the wing tip.
The forward fuselage (cockpit
) is constructed of Kevlar
, carbon and glass fiber laminate, reinforced by a double skin on the sides with integrated surrounding canopy frame and seat pan mounting flanges. The single-piece canopy hinges sideways and opens to the right. The aft fuselage section is constructed of a pure carbon fiber monolithic shell, stiffened by carbon fiber/foam core bulkheads and glass fiber webs.
The horizontal stabilizer is constructed of glass fiber/foam core sandwich with carbon fiber reinforcements. The elevator halves are a hybrid composite (carbon and glass fiber) monolithic shell. The vertical stabilizer
is carbon fiber/foam core sandwich construction. The single-piece rudder
is constructed of glass fiber/foam core sandwich.
The flight controls
are all push/pull tubes except for the rudder, which is controlled via cables.
The Nimbus-4DM is powered by a liquid-cooled 44 kW Bombardier
(Rotax
) model 535C engine with a 3:1 belt
reduction drive
. The powerplant is housed in the fuselage immediately aft of the wing. An electrically driven spindle drive (jackscrew
) extends the propeller pylon upwards and forward from the engine bay. When stowed, two doors mounted to the rear fuselage conceal the powerplant. The jackscrew is attached between the airframe and the upper forward end of the pylon such that when the jackscrew is retracted (shortened) the pylon is pulled upwards and forward into its flight position.
A 4DM holds the world record for speed over a 500km course - 306.8 km/h (190.6 mph) which is in excess of its Vne. It was flown by Klaus Ohlmann
and Matias Garcia Mazzaro on 22 December 2006.
(NTSB) investigators queried the German Luftfahrt-Bundesamt
(LBA), Germany's equivalent of the U.S. Federal Aviation Administration
(FAA) regarding the accident history of the Nimbus-4DM in conjunction with a 1999 accident near Minden, Nevada
where both occupants of the aircraft were killed. In this accident, the glider broke up in flight during the recovery phase after a departure from controlled flight while maneuvering in thermal
lift
conditions. Airborne witnesses in other gliders who saw the beginning of the accident sequence said the glider was in a tight turn, as if climbing in a thermal, when it entered a spiral. With a 45-degree nose-down attitude, the speed quickly built up as the glider completed two full rotations. The rotation then stopped, the flight stabilized on a northeasterly heading, and the nose pitched further down to a near-vertical attitude (this is consistent with the spin recovery technique specified in the Aircraft Flight Manual (AFM)). The glider was observed to level its attitude, with the wings bending upward and the wing tips coning higher, when the outboard wing tip panels departed from the glider, the wings disintegrated, and the fuselage dove into the ground. Several witnesses estimated that the wing deflection reached 45 degrees or more before the wings failed. Examination of the wreckage disclosed that the left and right outboard wing sections failed symmetrically at two locations.
In this case, the NTSB determined "that the probable cause of this accident was the pilot's excessive use of the elevator control during recovery from an inadvertently entered spin and/or spiral dive during which the glider exceeded the maximum permissible speed, which resulted in the overload failure of the wings at loadings beyond the structure's ultimate design loads."
There were then only three previous accidents worldwide on file with the Federal Bureau of Aircraft Accidents Investigation (BFU), Germany's equivalent of the NTSB. The first was a non-injury long landing accident in Fayence
, France, on September 4, 1994. The second involved a collision with the ground during takeoff in Fuentemilanos, Spain, on July 27, 1997, which resulted in two fatalities. The improper installation of the horizontal stabilizer led to the third accident in Lüsse
, Germany, on June 13, 1999, in which two occupants were injured during an attempted takeoff when the stabilizer separated from the empennage
just after liftoff.
Regarding other service/accident experience with the Nimbus-4 family of gliders, the BFU has recorded four incidents/accidents with the single-seat versions. Three events are known of non-injury accidents during off-field landings, and one fatal accident was due to collision with a mountain.
Additionally, during training for the World Gliding Championships
in New Zealand in 1995, a Nimbus-4 (owned by the French Air Force
) was destroyed in a midair breakup accident. The glider entered a wave cloud, lost control, and broke up at a speed beyond 400 km/h (The never exceed speed, or "Vne" is 285 km/h, and the design dive speed, or "Vd
", is 324 km/h). The pilot survived by bailing out.
According to the LBA, "As far as we know, none of the incidents/accidents recorded indicated a technical failure."
NTSB investigators became aware of another accident involving a Nimbus-4DM that occurred in Spain shortly after the Minden, Nevada, accident. According to the Comisión de Investigación de Accidentes e Incidentes de Aviación Civil, Spain's equivalent of the NTSB, the glider broke up in flight following a high-speed excursion beyond Vne. According to preliminary information supplied by the Spanish authorities, the pilot stated they were in a turn when a heavy thermal caused the glider to enter a steep descending spiral. The pilot could not recover the aircraft from the spiral and the airspeed quickly exceeded Vne. The pilot then reported that the right wing failed and he bailed out.
Movie of Nimbus-4D
Glider (sailplane)
A glider or sailplane is a type of glider aircraft used in the sport of gliding. Some gliders, known as motor gliders are used for gliding and soaring as well, but have engines which can, in some cases, be used for take-off or for extending a flight...
designed by Klaus Holighaus
Klaus Holighaus
Klaus Holighaus was a glider designer, glider pilot and entrepreneur.Klaus Holighaus was born in Eibelshausen, Germany. He started his career in gliding when he was an engineering student at the University of Darmstadt, where he was a member of its Akaflieg...
and manufactured by Schempp-Hirth Flugzeugbau GmbH in Kirchheim
Kirchheim unter Teck
Kirchheim unter Teck is a town in Baden-Württemberg, Germany, in the district of Esslingen. It is located on the small river Lauter, a tributary of the Neckar. It is situated near the Teck castle, approximatively 25 km southeast of Stuttgart...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. The Nimbus-4 first flew in 1990.
Design and development
The Nimbus-4 family is a direct derivative of its predecessors at the highest performance end of the Schempp-Hirth product range, the Nimbus-2Schempp-Hirth Nimbus-2
|-See also:-References:*Thomas F, Fundamentals of Sailplane Design, College Park Press, 1999*Simons M, Segelflugzeuge 1965-2000, Eqip, 2004***...
and Nimbus-3. In total , 44 single-seat and 100 two-seat models had been produced. The wing has a multi-tapered planform
Planform
In aviation, a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing. Of all the myriad planforms used, they can typically be grouped into those used for low-speed flight, found on general aviation aircraft, and those used for high-speed flight, found on many military...
and the wingspan
Wingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
was increased to 26.5 metres. The aspect ratio
Aspect ratio (wing)
In aerodynamics, the aspect ratio of a wing is essentially the ratio of its length to its breadth . A high aspect ratio indicates long, narrow wings, whereas a low aspect ratio indicates short, stubby wings....
is 38.8. The fuselage was also lengthened, and a larger rudder was fitted.
The manufacturer claims this glider has a glide ratio of better than 60:1 at a best glide airspeed of 110km/h (59 knots), meaning it can glide over 60 kilometres on course for every 1000 metres of altitude lost in still air.
There is a two seat version, the 4D, and motor glider
Motor glider
A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: A fixed wing aerodyne equipped with a means of propulsion ,...
versions with either turbo engines (designation T) or self-launching engines (designation M).
Nimbus-4DM
The Nimbus-4DM is typical of the Nimbus-4 design, except for variations in cockpit and powerplant configuration and associated operating limitations. It is a 2-seat, high-performance motorized glider, constructed from fiber reinforced plastic (FRP) composites, featuring full span flight controls and a T-tailT-tail
thumb|right|Grob motor gliderA T-tail is an aircraft tail stabilizer configuration in which the horizontal surfaces are mounted to the top of the vertical stabilizer. Traditionally, the horizontal control surfaces are mounted to the fuselage at the base of the vertical stabilizer...
(with fixed horizontal stabilizer and two-piece elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...
). The manufacturing process uses a hand lay-up of composite material plies and epoxy resins.
The wing's 26.5-meter (87-foot) span consists of three sections per side, consisting of a wing tip
Wing tip
A wing tip 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:* Squared-off...
, outboard section, and inboard section. The inboard sections mate at the fuselage and the outer wing sections mate with the inboard sections approximately 12.6 feet outboard of the fuselage root chord. The wing shells are a carbon fiber
Carbon fiber
Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...
/foam core sandwich construction with one main spar constructed of a glass fiber/foam core shear web and carbon fiber spar
Spar (aviation)
In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries flight loads and the weight of the wings whilst on the ground...
flanges. A single-vane flap
Flap (aircraft)
Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...
spans the entire inboard wing section. Three sections of ailerons (that is, inboard, center, and outboard) span the outboard wing section with a fourth aileron, used to minimize the effects of adverse yaw, attached to the wing tip.
The forward fuselage (cockpit
Cockpit
A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin...
) is constructed of Kevlar
Kevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
, carbon and glass fiber laminate, reinforced by a double skin on the sides with integrated surrounding canopy frame and seat pan mounting flanges. The single-piece canopy hinges sideways and opens to the right. The aft fuselage section is constructed of a pure carbon fiber monolithic shell, stiffened by carbon fiber/foam core bulkheads and glass fiber webs.
The horizontal stabilizer is constructed of glass fiber/foam core sandwich with carbon fiber reinforcements. The elevator halves are a hybrid composite (carbon and glass fiber) monolithic shell. The vertical stabilizer
Vertical stabilizer
The vertical stabilizers, vertical stabilisers, or fins, of aircraft, missiles or bombs are typically found on the aft end of the fuselage or body, and are intended to reduce aerodynamic side slip. It is analogical to a skeg on boats and ships.On aircraft, vertical stabilizers generally point upwards...
is carbon fiber/foam core sandwich construction. The single-piece rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
is constructed of glass fiber/foam core sandwich.
The flight controls
Aircraft flight control systems
A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight...
are all push/pull tubes except for the rudder, which is controlled via cables.
The Nimbus-4DM is powered by a liquid-cooled 44 kW Bombardier
Bombardier Aerospace
Bombardier Aerospace is a division of Bombardier Inc. and is the third-largest airplane manufacturer in the world. It is headquartered in Dorval, Quebec, Canada.- History :...
(Rotax
Rotax
BRP-Powertrain GmbH & Co KG , commonly known simply as Rotax, is an Austrian engine manufacturer. It develops and produces four-stroke and advanced two-stroke engines for Bombardier Recreational Products products as well as for motorcycles, karts,...
) model 535C engine with a 3:1 belt
Belt (mechanical)
A belt is a loop of flexible material used to link two or more rotating shafts mechanically. Belts may be used as a source of motion, to transmit power efficiently, or to track relative movement. Belts are looped over pulleys. In a two pulley system, the belt can either drive the pulleys in the...
reduction drive
Reduction drive
A reduction drive is a mechanical device to shift rotational speed. A planetary reduction drive is a small-scale version using ball bearings in an epicyclic arrangement instead of toothed gears....
. The powerplant is housed in the fuselage immediately aft of the wing. An electrically driven spindle drive (jackscrew
Jackscrew
A jackscrew is a type of jack which is operated by turning a leadscrew. In the form of a screw jack it is commonly used to lift heavy weights such as the foundations of houses, or large vehicles.-Advantages:...
) extends the propeller pylon upwards and forward from the engine bay. When stowed, two doors mounted to the rear fuselage conceal the powerplant. The jackscrew is attached between the airframe and the upper forward end of the pylon such that when the jackscrew is retracted (shortened) the pylon is pulled upwards and forward into its flight position.
A 4DM holds the world record for speed over a 500km course - 306.8 km/h (190.6 mph) which is in excess of its Vne. It was flown by Klaus Ohlmann
Klaus Ohlmann
Klaus Ohlmann, born 1952 in Neustadt, Germany is a German glider pilot who has established 36 world records approved by FAI. Among these is the record for a free distance flight with up to 3 turn-points by flying 3,009 km from Chapelco Airport at San Martín de los Andes in a Schempp-Hirth Nimbus 4...
and Matias Garcia Mazzaro on 22 December 2006.
Accident history
U.S. National Transportation Safety BoardNational Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
(NTSB) investigators queried the German Luftfahrt-Bundesamt
Luftfahrt-Bundesamt
The Luftfahrt-Bundesamt is the national civil aviation authority of Germany headquartered in Braunschweig...
(LBA), Germany's equivalent of the U.S. Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
(FAA) regarding the accident history of the Nimbus-4DM in conjunction with a 1999 accident near Minden, Nevada
Minden, Nevada
Minden is a census-designated place in Douglas County, Nevada, United States. The population was 2,836 at the 2000 census. It is the county seat of Douglas County and is adjacent to the city of Gardnerville. It is named after the town of Minden, in the German state of North Rhine-Westphalia. It...
where both occupants of the aircraft were killed. In this accident, the glider broke up in flight during the recovery phase after a departure from controlled flight while maneuvering in thermal
Thermal
A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
lift
Lift (soaring)
Gliding flight is heavier-than-air flight without the use of thrust. It is employed by gliding animals and by aircraft such as gliders. The most common human application of gliding flight is in sport and recreation using aircraft designed for this purpose...
conditions. Airborne witnesses in other gliders who saw the beginning of the accident sequence said the glider was in a tight turn, as if climbing in a thermal, when it entered a spiral. With a 45-degree nose-down attitude, the speed quickly built up as the glider completed two full rotations. The rotation then stopped, the flight stabilized on a northeasterly heading, and the nose pitched further down to a near-vertical attitude (this is consistent with the spin recovery technique specified in the Aircraft Flight Manual (AFM)). The glider was observed to level its attitude, with the wings bending upward and the wing tips coning higher, when the outboard wing tip panels departed from the glider, the wings disintegrated, and the fuselage dove into the ground. Several witnesses estimated that the wing deflection reached 45 degrees or more before the wings failed. Examination of the wreckage disclosed that the left and right outboard wing sections failed symmetrically at two locations.
In this case, the NTSB determined "that the probable cause of this accident was the pilot's excessive use of the elevator control during recovery from an inadvertently entered spin and/or spiral dive during which the glider exceeded the maximum permissible speed, which resulted in the overload failure of the wings at loadings beyond the structure's ultimate design loads."
There were then only three previous accidents worldwide on file with the Federal Bureau of Aircraft Accidents Investigation (BFU), Germany's equivalent of the NTSB. The first was a non-injury long landing accident in Fayence
Fayence
Fayence is a commune in the Var department in the Provence-Alpes-Côte d'Azur region in southeastern France.Fayence is one of a series of "perched villages" overlooking the plain between the southern Alps and the Esterel massif, which borders the sea between Cannes and Saint-Raphaël. Fayence is a...
, France, on September 4, 1994. The second involved a collision with the ground during takeoff in Fuentemilanos, Spain, on July 27, 1997, which resulted in two fatalities. The improper installation of the horizontal stabilizer led to the third accident in Lüsse
Lusse
Lusse is a commune in the Vosges department in Lorraine in northeastern France....
, Germany, on June 13, 1999, in which two occupants were injured during an attempted takeoff when the stabilizer separated from the empennage
Empennage
The empennage , also known as the tail or tail assembly, of most aircraft gives stability to the aircraft, in a similar way to the feathers on an arrow...
just after liftoff.
Regarding other service/accident experience with the Nimbus-4 family of gliders, the BFU has recorded four incidents/accidents with the single-seat versions. Three events are known of non-injury accidents during off-field landings, and one fatal accident was due to collision with a mountain.
Additionally, during training for the World Gliding Championships
World Gliding Championships
The World Gliding Championships is a gliding competition held every two years or so by the FAI Gliding Commission. The dates are not always exactly two years apart, often because the contests are sometimes held in the summer in the Southern Hemisphere....
in New Zealand in 1995, a Nimbus-4 (owned by the French Air Force
French Air Force
The French Air Force , literally Army of the Air) is the air force of the French Armed Forces. It was formed in 1909 as the Service Aéronautique, a service arm of the French Army, then was made an independent military arm in 1933...
) was destroyed in a midair breakup accident. The glider entered a wave cloud, lost control, and broke up at a speed beyond 400 km/h (The never exceed speed, or "Vne" is 285 km/h, and the design dive speed, or "Vd
V speeds
In aviation, V-speeds are standard terms used to define airspeeds important or useful to the operation of all aircraft including fixed-wing aircraft, gliders, autogiros, helicopters, and dirigibles...
", is 324 km/h). The pilot survived by bailing out.
According to the LBA, "As far as we know, none of the incidents/accidents recorded indicated a technical failure."
NTSB investigators became aware of another accident involving a Nimbus-4DM that occurred in Spain shortly after the Minden, Nevada, accident. According to the Comisión de Investigación de Accidentes e Incidentes de Aviación Civil, Spain's equivalent of the NTSB, the glider broke up in flight following a high-speed excursion beyond Vne. According to preliminary information supplied by the Spanish authorities, the pilot stated they were in a turn when a heavy thermal caused the glider to enter a steep descending spiral. The pilot could not recover the aircraft from the spiral and the airspeed quickly exceeded Vne. The pilot then reported that the right wing failed and he bailed out.
Joint Airworthiness Requirements Certification
The LBA issued type certificate No. 868 on July 11, 1995, certificating the Nimbus-4DM glider in the standard class, utility category. The certification basis listed on the type certificate is Joint Airworthiness Requirements (JAR) 22 for Sailplanes and Powered Sailplanes, effective June 27, 1989, inclusive of Change 4 and amendments 22/90/1, 22/91/1, and 22/92/1. Exemptions to the JARs on the type certificate included 22.201(f)(5)(ii), 22.153, 22.173(b), 22.175(a), and 22.207(a). A special compliance was established on the basis of an equivalent level of safety with JAR 22.1093(b).Variants
The Nimbus-4DM is a model of the "Nimbus-4 Family," which consists of single-seat and two-seat gliders and motorgliders. The different models are (production data ):- Nimbus-4: a single seat glider, Type Certified in Germany January 1, 1994. Total number produced: 11
- Nimbus-4D: a two-seat glider, Type Certified in Germany February 24, 1995. Total number produced: 9
- Nimbus-4T: a single seat self-sustaining motor glider with a retractable engine, Type Certified in Germany June 15, 1993. Total number produced: 12
- Nimbus-4M: a single seat self-launching motor glider with a retractable engine, Type Certified in Germany January 1, 1994. Total number produced: 10
- Nimbus-4DT: a two seat self-sustaining motor glider with a retractable engine, Type Certified in Germany May 5, 1995. Total number produced: 6
- Nimbus-4DM: a two seat self-launching motor glider with a retractable engine, Type Certified in Germany November 7, 1995. Total number produced: 37
Specifications (4DM unless otherwise specified)
External links
Schempp-Hirth's homepageMovie of Nimbus-4D