Schempp-Hirth Mini-Nimbus

Mini-Nimbus
Mini Nimbus HS-7
Role	15 Metre class sailplane
National origin	Germany
Manufacturer	Schempp-Hirth
Designer	Klaus Holighaus
First flight	18 September 1976
Number built	159

The Schempp-Hirth Mini Nimbus is a 15 Metre-class glider designed and built by Schempp-Hirth GmbH in the late 1970s.

Design and development

In designing the Mini-Nimbus, Klaus Holighaus incorporated the flapped wings from the Glasflügel 303 Mosquito, with the fuselage of the Standard Cirrus. The name "Mini Nimbus" was adopted to distinguish it from longer-wingspan Nimbus models. It first flew on 18 September 1976.

The Mini Nimbus range all feature self-connecting controls, of Glasflügel design, for added safety and ease of rigging, and have been incorporated in all newer Schempp-Hirth models. The trim lever is connected to the flap operating rod and needs to be set only once per flight; thereafter changes in flap setting (-7 to +10 degrees) automatically provides trim compensation.

Variants

Based on the Standard Cirrus, the original Mini-Nimbus HS-7 design had an all-moving tailplane and fibre glass wing spars. A tailplane anti-balance tab was a required modification for certification in the United Kingdom after flight testing by Derek Piggott on behalf of the British Gliding Association revealed very low stick forces and marginal pitch stability of the HS-7 version. A conventional tail was added for the Mini-Nimbus B version. The conventional horizontal stabiliser/elevator configuration was less sensitive to inputs by the pilot making it easier to fly without constantly making small adjustments to the pitch attitude. This was due to the much larger control surface of the former compared to the later configuration.

The Mini-Nimbus C version had an increased maximum take off weight. Additionally, lighter weight wings with spars and shells of carbon-fibre was available as an option for the C version (meaning that only some Mini Nimbus C has carbon fibre wings, the "C" is often thought to represent "Carbon" which is not correct).

The Nimbus 2C and the Mini Nimbus C were the first two carbon-fibre aircraft to be built by Schempp-Hirth. The use of carbon-fibre significantly lightened the Mini Nimbus improving its climbing performance and increasing water ballast capacity while making assembly and disassembly much easier.

Performance

The Mini-Nimbus glide ratio was somewhat less competitive than its primary rival in sailplane race competitions, the Alexander Schleicher ASW 20. However its superior climbing performance (altitude gained over time while climbing in lifting air) over its rivals made it the choice of some successful international soaring competition pilots in the late 1970s.

A unique capability of the Mini Nimbus is its powerful trailing-edge integrated air brake/flap system with a 70 kn terminal dive velocity which gives the aircraft a superior short field and steep landing approach capability. This is a significant safety enhancing capability especially during recreational or competitive cross-country flights where the risk of damage from landing in small rural cultivated fields or pastures is considerable.

Production

159 Mini-Nimbuses were built, many of which remain in use today and are sought out by pilots wishing to get the best competitive performance possible for the least cost.

Competition use

It was the favoured aircraft of former American world champion soaring pilot George Moffat in his attempt in the late 1970s to win two USA soaring championships where he proved that the skill of the pilot can overcome performance differences between competing aircraft. George Moffat won the 1977 European Gliding Championships flying a Mini Nimbus. The Mini Nimbus remains a formidable competitor in the Sports Class of sailplane racing where handicaps are allowed in scoring.

Specifications

General characteristics

• Crew: One
• Capacity: 125 kg / 275 lb water ballast (190kg for version C)
• Length: 6.41 m (21 ft 0 in)
• Wingspan: 15.00 m (49 ft 3 in)
• Height: 1.31 m (4 ft 4 in)
• Wing area: 9.86 m² (107 ft²)
• Aspect ratio: 23
• Wing profile: Wortmann FX
• Empty weight: approx: 235 kg ; approx version C with carbon fibre: less than 230 kg (approx: 536 lb ; approx version C with carbon fibre: less than 500 lb)
• Gross weight: version HS-7 & B: 450 kg ; version C: 500 kg (version HS-7 & B: 990 lb ; version C: 1100 lb)

Performance

• Maximum speed: 250 km/h (160 mph)
• Maximum glide ratio: 42 (Measured ~39)
• Rate of sink: 0.57 m/s (104 ft/min)

See also

Related development

• Schempp-Hirth Standard Cirrus
• Schempp-Hirth Ventus
  

Aircraft of comparable role, configuration and era

• Eiri-Avion PIK-20
• Glasflügel Mosquito
• Rolladen-Schneider LS3
• Schleicher ASW 20
• Slingsby Vega
  

Related lists

• List of gliders
  

References

Bibliography

• Hardy, Michael. Gliders and sailplanes of the World. London: Ian Allen, 1982. ISBN 0-7110-1152-4.

Further reading

• Simons M, Segelflugzeuge 1965-2000, Eqip, 2004
• Peter F Selinger. "Vom Wolf zum Discus". ISBN 3-87943-448-4

External links

• Mini-Nimbus Owners Group
• British Gliding Association data sheet
• Manufacturers type page - German language
• Mini Nimbus Yahoo group
• Flight test evaluation - Soaring magazine, December 1977
• Mini Nimbus production list