Akaflieg Stuttgart Phönix-T fs-24
Notable as being the first sailplane to be built of glassfibre, design of the Phonix was started at the Stuttgart Akademische Fliegergruppe under R.Eppler and H. Na'gele in 1951. Originally balsa wood construction with a strengthened outer skin of paper-and-glue layers was decided upon with the idea of reducing weight, but the Phonix project had to be abandoned for a time. Work was continued when the Stuttgart Fliegergruppe was given a grant for further research, and by now the new glassfibre strengthened polyester resins were available as a constructional material. The Phonix was redesigned to a basically balsa wood/glassfibre sandwich form of construction. At first a conventional tail unit with low-set tailplane was featured, but this was later replaced by a T-tail; the landing gear is retractable.
The monocoque fuselage is built in two pieces with a sandwich skin with balsa wood filling and an outer skin of glassfibre. The wing attachment, controls and fittings are installed before the two pieces are glued together with the glassfibre skin overlapping; weight carrying points and the edge of the cockpit canopy are strengthened with plywood. The wings and tail unit are of similar balsa wood/glassfibre sandwich construction, the ailerons, flaps and rudder being cut out after the glueing process is completed.
The first made its first flight on 27 November 1957. Altogether eight Phonixes were built and all of them were still flying 21 years after the prototype first took to the air.
Akaflieg Stuttgart FS-24 Phonix
Wing span: 16m / 52 ft 6 in
Length: 22 ft 5.25 in
Wing area: 14.36 sq.m / 154.6 sq.ft
Empty Weight: 180kg / 362 lb
Gross Weight: 330kg / 584 lb
Wing Load: 22.9kg/sq.m
Aspect ratio: 17.83
Airfoil: Eppler 91
Max speed: 107 mph
L/DMax: 40 @ 79kph / 48 mph
MinSink: 0.59 m/s @ 68 kph / 1.7 ft/sec at 43 mph
No. of Seats: 1