The Orkan (Whirlwind) II was the second aircraft designed by Tadeusz Grzmilas and followed the
Orkan I, a
glider. Grzmilas was serving in the Polish air force at
Poznań and obtained permission to build it in the military workshops there during the 1927-8 winter, with the Second National Lightplane Contest, scheduled for late October 1928 in
Warsaw, in mind. He took it on its first flight on either 9 September 1928 or 5 October 1928. It had a two part, thick, constant thickness, rectangular plan, two
spar wing either with
plywood covering ahead of the forward spar and
canvas covered behind or entirely fabric covered.
Ailerons extended to the wing tips. Each half-wing was braced to the lower fuselage
longerons by a pair of parallel, steel tube
struts to the spars and supported at the central joint low over the fuselage on inverted V-struts. The Orkan II was powered by a
Anzani six-cylinder
radial engine which Grzmilas had won as a prize for his success at the Second Polish Glider Contest of 1925, flying the Orkan I. It was mounted
uncowled via a rounded, light alloy covered nose to the rectangular section, wooden framed and ply covered fuselage. An open
cockpit under the wing
trailing edge w\s provided with a rounded cut-out for a better upward field of view. The horizontal tail, like the wing, was rectangular in plan and fabric covered. It was mounted on top of the fuselage and strut-braced on each side to the lower longeron; the
elevators had a cut-out to allow movement of the
rudder, which was fabric covered and rectangular in profile apart from its lower edge, angled for ground clearance. The fabric covered
fin had a strongly cropped triangular profile. The Orkan II's fixed, conventional
landing gear had mainwheels joined by a single axle on steel tube V-struts from the lower fuselage longerons at the bottom of the wing struts, together with a tall tailskid. Soon after its first flight, the Orkan II took part in the Second National Lightplane Contest. Flown by Grzmilas it gained second place overall, with first places for the shortest take-off () and for the greatest altitude reached in 30 minutes (). After the contest Grzmilas flew the Orkan from time to time during his service career, during which he was based at
Dęblin,
Kraków and
Lublin. In September 1939 he stored it in the L.W.S. factory at Lublin where it was later destroyed. ==Specifications==