The IIL IS-11 was an

aerobatic Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aerial" and "acrobatics". Aerobatics are performed in aeroplanes and glid ...

, single seat glider, designed and built in Romania in 1959. It was built in small numbers.

Design and development

From about 1950 to his death in February 1981, Iosif Silimon was Romania's most prominent glider designer, his aircraft distinguished by his initials. His single seat IS-11 was a wooden, high wing aerobatic sailplane. The cantilever high wing of the IS-11 was mounted with a dihedral of 2.5°. It was built around a single spar with a

plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...

covered torsion box ahead of it around the leading edge. The rest of the wing was also ply covered. In plan the wing was symmetrically straight tapered. Its mass balanced

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

s were slotted and fabric over ply covered. The IS-11 had short span spoilers, opening both above and below the wing, mounted at mid-

chord Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord ( ...

just inboard of the ailerons. The wing tips carried the small, streamlined bodies known as salmons, common at the time. The fuselage of the IS-11 was an oval section plywood monocoque. The pilot sat in a semi-reclining position in a single seat cockpit under a single piece, side opening perspex canopy which, with a short, fixed transparency behind it stretched from the nose into the leading edge of the wing. Its

undercarriage Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...

comprised a very short, rubber sprung skid under the nose and a fixed, unsprung monowheel semi-recessed into the fuselage under the forward wing and fitted with a brake. From the high wing the fuselage tapered aft to a conventional empennage. A narrow, ply covered fin and a fabric covered rudder which extended down to the keel together formed a straight edged vertical tail with rounded heel and tip. The fin also mounted a straight edged, fabric over ply covered tailplane placed just above the fuselage, carrying straight tapered, similarly skinned elevators. These were balanced by a bob weight within the fuselage and had gaps both at their roots to clear the fin and at their tips to clear rearward tailplane extensions, with a small central cut out for rudder movement. There was a trim tab on the starboard elevator and a tail bumper under the rudder hinge. The IS-11 was first flown on 16 December 1959 and a few more were built during 1961.

Specifications

References

{{Iosif Silimon aircraft 1950s Romanian sailplanes Aircraft first flown in 1959 High-wing aircraft