LET L - 13 Blaník The L - 13 Blaník is a two seater trainer glider produced by Let Kunovice since 1956 . It is the most numerous and widely used glider in the world . In United States Air Force Academy service , it is designated TG - 10C and is used for basic flight training . Development . The L - 13 Blaník was designed by Karel Dlouhý of VZLÚ Letňany ca . 1956 , building upon the experience gained with the Letov XLF - 207 Laminar , the first Czech glider to employ laminar flow wing profiles . The L - 13 was developed as a practical glider suitable for basic flight instruction , aerobatic instruction and cross - country training . This design concept was combined with true and tested technology : metal construction , NACA laminar profiles and many standard - issue components of the soviet aerospace industry . The Blaník entered production in 1958 and quickly gained popularity as an inexpensive , rugged and durable type , which was easy to fly and operate . It was widely adopted in the Soviet bloc and was exported in large numbers to Western Europe and North America . Total production was in excess of 2650 , or more than 3000 if variants are included . Nearly half a century after its first flight it is still the most common glider in the World . In the cross - country role the Blaník achieved many two - seater World distance records during the 1960s in spite of having only fair performance . The Blaník inspired other designs , notably the Démant and L - 21 Spartak single - seaters developed to equip the Czech team in the 1956 and 1958 World Championships . Characteristics . The effectiveness of the Blaník as a primary trainer is due to a blend of characteristics that facilitate progress of " ab initio " students towards solo flight , namely : slow landing speed , ample control deflections and an effective rudder . These are in effect typical of wood - and - fabric primary trainers such as the ASK 13 , which the Blaník resembles in handling , though not in materials , construction and aerodynamics . For this reason , pilots trained in the Blaník require " differences training " in a modern two - seater before transitioning to high performance plastic single seaters . The Blaník is stressed for simple aerobatics . It cannot perform advanced maneuvers such as snap rolls ( flick rolls in British English ) and inverted flight is strictly single - occupant . Therefore , intermediate level aerobatic training in the Blaník must be done in solo flight with the instructor on the ground or in another aircraft . There are two piloting issues that pilots should be aware of . The wheel retracts counter - intuitively , with the gear handle moving forward for wheel up and back for down ( this is reversed on the L - 23 ) . More importantly , the spoiler and flap handles have the same shape and are close to each other . This has led to a number of incidents where pilots have mistakenly operated the wrong handle , particularly in the landing pattern . Instructors recommend that a positive visual check of the spoiler operation be made during the prelanding checklist , and that the pilot ' s hand stay on the handle right through full stop . The Blaník empennages are vulnerable . The horizontal stabiliser is low enough to be damaged when landing in brush , and one must not push on the vertical fin when ground handling as it is not stressed to carry loads fore - and - aft . Specifications . General characteristics Performance