Schempp-Hirth HS-7 Mini-Nimbus
The Nimbus 2's 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. The Mini Nimbus (HS 7) of 1976 was the first of Klaus Holighaus for the FAI-15m class. A single-seat, 15 metre wingspan sailplane with a new wing with both dive brakes and flaps, series one manufacture started in 1977 with fibre-glass. The wings stem from the Glasflugel Mosquito as well as most of the mechanics. Equipped with a trim system in which the pilot adjusts trim according to their weight and sets the flaps for the desired flying speed.
Water ballast is carried in sealed tanks lying along the spar. All controls connect automatically as the flying surfaces are installed, and the trim lever needs to be set only once per flight; thereafter changes in flap setting (-7 to +10 degree) automatically cause trim compensation.
The HS-7 Mini-Nimbus, designed by Dipl-Ing Klaus Holighaus, 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.
The original version has an all-moving horizontal tail, but the C model is made with a fixed horizontal stabiliser, optional carbon fiber wings and tail (which reduce the empty weight by 20 kg /44 lb) and a modified trim system.
Serial introduction of carbon fiber was first included on the Nimbus-2C, Mini-Nimbus-C, Janus-C and Janus-CM.The "C" has a carbon fiber wing and horizontal tail unit. A rear edge turning flap (a combination of spoiler and curving flaps) is common to all models, which lends unusual short landing characteristics to the Mini Nimbus. The Mini Nimbus elevator trim overlaid by the curving flap and the retractable landing gear was manufactured from GRP.
After 159 were built, manufacturing switched to the Ventus in 1980.
Schempp Hirth Mini Nimbus
Mini-Nimbus C (carbon-fibre wings)
Span: 49 ft 2.5 in
Length: 21 ft 0.5 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