Scheibe SF27 Zugvogel / SF-32
Lorraine Aviation Loravia LA-11 Topaze
SLCA SLCA-10 / LA-10
Scheibe's first postwar essay into the high performance field was the Zugvogel (or Migratory Bird) single-seat sailplane which had laminar flow wings of NACA 63-series section and with a forward sweep of 2.5°. This made its competition debut when it was flown by veteran test pilot Hanna Reitsch into the winning place in the 1955 German National gliding championships. It had the traditional Scheibe fabric-covered steel tube fuselage (with a fiberglass nose section) and wooden single-spar wing and tail surfaces, all-flying tail, the wing span being 16m (52 ft 6 in) with an aspect ratio of 18.3 and area of 150.16 sq ft. The Sf-27A has Schempp-Hirth type dive brakes and semi-reclining seating. The wing ribs are spaced only 4 inches apart and heavy plywood skins cover 85 % of the surface in order to help maintain the laminar profile.
Next version as the Zugvogel-II, which had an unswept wing of simpler construction, a simplified control system and various other changes over the initial version. This was developed into the Zugvogel-III, which first flew in prototype form in April 1957 and which differed from the Mk II only in having the wing span increased to 17m (55ft 9in) and a larger fin and rudder, the aspect ratio now being 20.0 and wing area 155.9sq ft. Further versions were the Zugvogel-IIIA and IIIB, the latter version, the prototype of which was completed in June 1962, having a redesigned nose and cockpit canopy, the stepped canopy of earlier versions being replaced by a longer flush fitting one-piece plastic canopy blending into a shorter, more pointed nose. The high cantilever wings have Schempp-Hirth aluminium air brakes, and depending on the degree of surface polishing the best glide ratio can be improved from 36:1 at 62 mph to 39:1.
Helen Dick flew a -3B to set the following U.S. national feminine single-place records: Distance (492.2 km./ 305.84 miles), goal (364.6 km/ 226.57 miles) and Out & Return (400.00 km./ 248.82 miles) between 1964 and 1967.
The SF-27 Zugvogel V, the prototype of which first flew on 12 May 1964, is a single-seat Standard class development of the Mk IIIB with cantilever shoulder instead of high wings of 15m (49 ft 2.5 in) span and Wortmann aerofoil sections; the tailplane is now an all-moving surface and more glassfibre is used in the fuselage structure. The wings have a single laminated beechwood box spar and plywood ribs, with a leading edge torsion box; the outer halves of the wings are plywood-covered, and the inboard halves are ply-covered to just behind the spar, the rest of the wings being part plywood- and part fabriccovered. The wooden ailerons are ply-covered and the Schempp-Hirth air brakes are of glassfibre and metal. The welded steel tube fuselage has the nose section back to the wing trailing edge covered with moulded glassfibre shell, and the rear section fabric covered over wooden stringers. There is a moulded glassfibre fairing over the wing/fuselage junction. The cantilever tail unit is of wood, with a ply- and fabric-covered tailplane, the fin is plywood-covered and the rudder fabric-covered; there is an antibalance tab in the tailplane. Landing gear consists of a non-retractable and unsprung monowheel ahead of the eg, with a brake, and a tailwheel. The pilot sits in an inclined seat under the moulded Plexiglas canopy, and there is a baggage compartment behind the seat.
Scheibe SF-27 Zugvogel V
The SF-27M, designed in 1967, is a single-seater powered verison of the SF-27 Zugvogel V, and was an early example of the completely retractable powerplant installation, the 26hp Hirth Solo vertically-opposed four-cylinder engine being mounted just aft of the wings and retracting backwards into the centre fuselage behind closed doors. This retractability gives the SF-27M about the same soaring performance as the Zugvogel V, and makes it capable of self-powered take-off as well as normal launching by winch or aero-tow; the engine installation weighs only about 88lb, so its effect on soaring performance is minimised.
The SF-27M is structurally similar to the Zugvogel V except that the fuselage centre section has been modified to take the engine, increasing the overall length, and the wings and control surfaces have been strengthened internally; the main wheel tyre size has also been increased. The engine is raised into position and retracted manually by a crank-driven draw chain pushrod system, swinging up into its operating position; raising and lowering it is very simple, requiring only 3.5 turns on the crank and being completed in five seconds. The doors over the engine and propeller bay open and close automatically while this is being done, the two-blade propeller of about 4ft 5in diameter being stopped in the vertical position for retraction. Engine starting is by a hand-operated cable, and a specially-designed ignition system facilitates easy starting. A fuel tank of 4.4 Imp gallons capacity is mounted in the fuselage behind the pilot.
The first Distance Diamond award for a powered sailplane flight was granted by the German Aero Club to Willibald Colle, who flew his SF-27M a distance of 334 miles from Elz to Le Rabot airfield, France, on 28 July 1968. Colle took off under his own power just before 11am, climbed to about 3,000ft and switched off and retracted the engine; he covered the distance to Le Rabot in about eight hours at between about 2,500 and 6,000ft, and the special barograph installed confirmed that the flight had been made without assistance from the engine. The SF-27M also won the single-seater class at the German Motor Glider competitions held in 1970 and 1971.
About 30 SF-27Ms were built. It was succeeded by the SF-32, also a single seater, which first flew in prototype form in May 1976 and is basically very similar, being powered by a 40hp Rotax 642 'flat twin' two-stroke driving a fixed-pitch two-blade wooden propeller, and mounted on a pylon and retracted into the fuselage in the same way as the SF-27M's but electrically instead of manually. The cantilever shoulder wings, which are built in two parts, are of 17m (55ft 9.25in) span instead of the SF-27M's 15m span, and are basically the same as the Swiss Neukom Elfe 17's, with an aluminium alloy main spar and a glassfibre and plywood/foam sandwich skin. There are Schempp-Hirth air brakes in the upper surfaces but unlike the Elfe 17 - no provision for water ballast. The fuselage is very similar to the SF-27M's and Zugvogel V's, being a welded steel tube structure with the nose section covered with a moulded glassfibre shell back to the wing trailing edge, the rear section being fabric-covered. The tail unit is very similar to the SF-27M's, with a geared anti-balance tab in the all-moving tailplane. Only the prototype SF-32 was built.
The Zugvogel V is built under licence in France by Lorraine Aviation as the Loravia LA-11 Topaze, this company having taken over production of the type from SLCA, which had built nine SF-27s under the designation SLCA-10 (now LA-10). The LA-11 has the monowheel lowered by 80mm and first flew on 15 October 1973; 18 LA-11s were built by SLCA and Loravia had built 30 by early 1976.
Wing span: 17m / 55.8ft
Wing area: 14.49sq.m / 156sq.ft
Empty Weight: 250kg / 551lb
Payload: 115kg / 254lb
Gross Weight: 365kg / 805lb
Wing Load: 25.19kg/sq.m / 5.2lb/sq.ft
Aspect ratio: 20
Airfoil: NACA 63(2)-616/614
L/DMax: 37 @93 kph / 50 kt / 58 mph
MinSink: 0.61 m/s / 2.0 fps / 1.18 kt
Span: 49 ft 2.5 in
Length: 23 ft 3.5 in
Wing area: 129.9 sqft
Aspect ratio: 18.6
Empty weight: 474 lb
Max weight: 728 lb
Min sinking speed: 2.10 ft/sec at 46 mph
Best glide ratio: 34:1 at 55 mph
Span: 55 ft 9.25 in
Length: 22 ft 11.5 in
Height: 4 ft 1.25 in
Wing area: 143.2 sqft
Aspect ratio: 21.73
Empty weight: 750 lb
Max weight: 992 lb
Max speed: 136 mph
Min sinking speed: 2.1 ft/sec at 50 mph
Best glide ratio: 37:1 at 56 mph
Take-off run: 656 ft
Range: 186 miles