Schempp-Hirth HS-2 Cirrus / HS-4 Standard Cirrus
This high performance single-seater is Schempp-Hirth KG's first sailplane of glassfibre construction and was designed and test flown by Dipl-lng Klaus Holighaus, who became a 50% shareholder in Schempp-Hirth in 1970 and five years later became co-owner of the reorganised Glasflűgel firm.
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 into a little box on the bottom of the rudder. To achieve good low speed and climb characteristics the new thick Wortmann FX 66 series wing section was used, 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 overcome by provision for water ballast, up to 216 lb of which can be carried. There are no flaps.
The fuselage is a glassfibre shell, 1.5mm thck, 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.
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.
The original Open Class Cirrus flown by Harro Wodl of Austria was first in the Open Class in the 1968 World Championships at Leszno in Poland.
Designed by Dipl-lng Klaus Holighaus, although the Standard Cirrus was a follow-on to the original Open Class Cirrus design, it was a completely different aircraft, with a 15 m wing of different Wortmann aerofoil section with the same root thickness/chord ratio of 19.6% as on the Cirrus and also without flaps, with airbrakes on the top surface only, an all-moving T-tail and a steel tube skeleton in the wing-fuselage center section. The Standard Class has a long flush-fitting one-piece Plexiglas canopy hinged at the starboard side.
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.
Despite a claimed L/D ratio of 38, measured performance by both Paul Bikle and Ricard H. Johnson demonstrated less than 36.
A ‘B’ model was produced that had 16m tips to further improve L/D and minimum sink values (to 38:1 and 118 ft/s respectively). Only 11 B models were produced.
In 1975 an improved to the original Standard Cirrus 15 m version called the Cirrus 75 was introduced with redesigned wing fairings, larger top-surface airbrakes airbrakes, redesigned wing fairings, a longer nose, 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 semireclining seat and has adjustable rudder pedals.
176 were manufactured under license by Burkhart Grob in Mindelheim, Germany. These changes resulted in a slightly improved L/D (37 vs 36) and minimum sink rate (124 ft/s vs. 128 ft/s).
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.
The Standard Cirrus was Schempp-Hirth’s second most successful aircraft in produced units.
After production in Germany ceased in 1971, the Standard Cirrus (Cirrus-VTC) was manufactured from 1972 in Vrsac, Serbia by Vazduhoplovno Tehnicki Centar (later Jastreb Fabrika Aviona Jedrilica) until 1977, first the Cirrus 75 and 75B version, and subsequently a modified Cirrus 81 with roomier cockpit and variable incidence tailplane. VTC had built about 60 by early 1975 under licence and production continued. VTC had built 14 Standard Cirrus 75-VTCs by early 1979.
Between 1977 and 1978, the French company Lanaverre Industrie, formed at Bordeaux in 1977 by Morin SA and the boatbuilding concern Yachting France; built 35 ships designated CS 11/75 L St. and CS 11/78 L St. These ships overlap the German serial numbers with serial numbers beginning at one. 30 had been completed by 1 January 1979 as the Lanaverre Standard Cirrus, also known as the SCAP Cirrus 78L.
Air Transport Certified.
HS-4 Standard Cirrus
Wing span: 17.74 m / 58.2 ft 2.5 in
Wing area: 12.6 sq.m / 135.6 sq.ft
Aspect ratio: 25
Airfoil: Wortmann FX 66-196/161
Length: 23 ft 7.25 in
Height: 5 ft 0 in
Empty Weight: 260 kg / 573 lb
Payload: 140 kg / 309 lb
Gross Weight: 460 kg / 1014 lb
Wing Load: 36.51 kg/sq.m / 7.48 lb/sq.ft
Water Ballast: 98 kg / 216 lb
Max speed: 137 mph (in smooth air)
Max aero-tow speed: 87 mph
L/DMax: 44 at 85 kph / 46 kt / 53 mph
MinSink: 0.50 m/s / 1.64 fps / 0.97 kt at 45 mph
No. Built: 183
Standard Cirrus 75
Span: 49 ft 2.5 in / 17,74 m
Length: 20 ft 9.75 in / 7,20 m
Height: 4 ft 4.75 in
Wing area: 107.6 sqft / 12,60 sq.m
Aspect ratio: 22.5
Empty wt: 487 lb / 260 kg
Max TO wt: 860 lb / 460 kg
Useful load: 393 lb
Water ballast: 139 lb
Wing loading: 8 lb/sq.ft / 26,6-36,5 kg/sq.m
Max speed: 137 mph / 119 kt
Rough air speed: 119 kt
Stall: 38 kt
Max aero-tow speed: 93 mph
Min sinking speed: 1.87 ft/sec at 44 mph
Sink: 2.2 fps @ 42.5 kt / 0,59 m/s @ 79 km/h
Best glide ratio: 38.5:1 at 56 mph
Lift to drag: 35 @ 51 kt
Max. L/D: 44 @ 85 km/h
HS-4 Standard Cirrus