A couple of additions and corrections. There seems to have been a numerical sequence beginning with the KB-1 but the numerals 1 and 2 are duplicated with an 'LK' series (Letov or Ljubljana + Kuhelj?). A few mysteries include the early dates for the Letov L-21 and L-22 (which some sources insist on giving the name 'Libis').
Obviously, the LIBIS 520 is not part of the regular sequence.
Ljubljana - Letov/LIBIS Aircraft Designations
KB-1 - 1948
Triglav shoulder-winged sailplane
- KB-1: Single-seat high-perf. sailplane, span 15.00 m
- KB-1: Designed to 1947 comp'n for Olympic glider
-- Jaroslav Koser & Stojan Hrovat student design *
-- *
Tehniška fakulteta of the Univerze v Ljubljani
-- aka Koser-Hrovat KB-1, Letov Kb-1, aka Koser K2A
--
Triglav after highest peak in Jura Alps
-- KB-1 based on Koser's 1946
Karavan glider project
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2007/04/kb1_pro.jpg
--
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=1545
LK-1 - 1955 4-seat high-wing lightplane, x 3
- LK-1: 1 x 160 hp Walter
Minor, span 13.00 m
- LK-1: Anton Kuhelj design as glider tug*
-- Orig. to have been a side-by-side 2-seater
-- YU-CLN mod. with enlarged tail, dorsal fin
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2019/11/002_LK1.jpg
--
https://www.modelarstvo.si/lk-1/
--
https://www.secretprojects.co.uk/threads/postwar-letov-projects.9733/#post-351772
KB-2 - 1949
Udarnik single-seat sailplane
- KB-2: Shoulder gull wing, span 15.00 m, x 1*
- KB-2: Designed to 1947 comp'n for Olympic glider
-- YU-4014, laminar-flow wings failed to perform
-- KB-2 designed by Dušan Cener & Marjan Slanovec
-- aka Cener-Slanovec KB-2
Udarnik
--
Udarnik translates as 'Striker'/'Shock Worker'
-- 3v:
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/3vues/Cener-Slanovec_KB-2_Udarnik_3v.jpg
--
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=1562
LK-2 - (Project) 1955 tandem 2-seat high-wing lightplane
- LK-2: Narrow-fuselage version of Letov LK-1
- LK-2: 1 x 160 hp Walter
Minor, span 11.30 m
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2019/11/002_LK2.jpg
--
https://www.modelarstvo.si/lk-2/
KB-3 - 1950
Jadran flying boat sailplane
- KB-3: KB-1 deriv. with planing hull + floats
-- Intended for Adriatic* flying clubs, x 6
-- Towed airborne by Aero-2H on floats
-- * 'Jadran' translates as 'Adriatic'
-- KB-3 prototype stored, Nikola Tesla, Belgrade
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2007/04/kb3_pro.jpg
--
https://www.gonzoaviation.com/AwEshop2UserFiles/image/jadralno more 640.jpg
4 - (??)
KB-5 - 1949
Triglav III shoulder-winged sailplane
- KB-5: Single-seat high-perf. sailplane, span 15.00 m
- KB-5:
Triglav evol. with impr. cockpit, V-tail
-- Constructed by the Slovenian Aviation Association
-- aka Koser KB-5
Triglav III after Jaroslav Koser
-- 3v:
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/3vues/Koser_KB-5_Triglav-III_3v.jpg
--
http://www.aerozaprega.si/images/razno/kb5/slika2.jpg
--
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=3100
KB-6 - 1952
Matajur 2-seat monoplane trainer/tourer
- KB-6 : Side-by-side seating, sliding bubble canopy
- KB-6 : Low-winged, fixed taildragger, aka Letov KB-6
- KB-6 : 1 x 135 hp SNECMA-Régnier 4L.00, span 10.60 m
-- aka 'KB-
Matajur'
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2019/11/002_matajur.jpg
- KB-6T:
Trised 3-seat KB-6 development, x 8
- KB-6T: 1 x 160 hp Walter
Minor 6-III-J 6-cyl.
- LIBIS-160: Modernized KB-6T devel., swept fin, x 11
- LIBIS 180: 1965 3-seat glider-tug development, x 10*
- LIBIS 180: 1 x 185 hp Lycoming O-435-1, span 10.60 m
-- * 1 burned at factory, 6 x 180s crash due to stalls
-- LIBIS 180 designed by
ing Marjan Slanovec, 1956
-- 3v:
https://only-paper.ru/_nw/136/41307053.jpg
--
https://www.modelarstvo.si/libis-180/
7 - (??)
8 - (??)
KB-9 - 1952 single-seat high-performance saiplane
- KB-9: New 16.00 m wing on KB-2
Udarnik fuselage
-- aka Letov KB-9
10 - (??)
KB-11 - 1959
Branko 4-seat low-winged light a/c
- KB-11: All-metal, retr. tricycle u/c KB-6 successor
- KB-11: 1 x 185 hp Lycoming O-435-1, span 10.69 m
-- 5 x KB-11 built, intended as tourer/business type
--
http://old.opensoaring.com/NaKrilih/Pogovor/Pogovori_15/Slike_ivan/Ivot7401.jpg
KBL-12 - (Project) 1954 tandem two-seat jet trainer
- KBL-12: Low-wing, version with side or top inlet(s)
- KBL-12: 1 x 150 kg turbojet engine,* span 6.50 m
-- * Engine speculated to be Turbomeca
Palas
-- KBL-12 designed by
ing. Marjan Slanovec
--
https://www.modelarstvo.si/kbl-12/
13 - (??)
KBI-14 - 1956
Mačka aerobatic glider
- KBI-14: Single-seat, shoulder-wing, span 10.00 m
-- Letov KBI-14,
Mačka also built by Ikarus and SVC
--
https://en.wikipedia.org/wiki/SVC_Mačka
15 - (??)
16 - (??)
LIBIS 17 - 1961 2-seat training sailplane
- LIBIS 17: Orig. known as the LIBIS KB-17
-- Prototype flew Oct 1961, prod. June 1963
- LIBIS 17: Shoulder-winged, span 17.00 m
-- Design team under
ing. Jože Prhavc
-- Mixed const., expanded foam stiffening
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2007/04/libis17_pro.jpg
--
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=3098
- LIBIS 17 (??): Motor-glider conversion, no details
--
https://www.modelarstvo.si/wp-content/uploads/2007/04/libis17b.jpg
LIBIS 18 - 1964 single-seat Standard Class sailplane
- LIBIS 18: 1964 prototype, competed in '65 World Cup
- LIBIS 18: Shoulder-wing, wooden const., span 14.98 m
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2007/04/libis18_pro.jpg
- VTC
Trener: 1969 mod. 2nd prototype, all-moving tail
- VTC
Trener: Production version by VTC (Vršac), x 50 (?)
-- 3v:
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/3vues/Libis-18_3v.jpg
--
http://www.aeroklub-sarajevo.ba/IstorijaJedrilica/AK Postojna/trener.jpg
--
http://all-aero.com/index.php/60-gliders/15342-vtc-trener
19 - (??)
20 - (??)
L-21 - 1955 'Libis' single-seat training glider
- L-21 : Braced high-wing glider, span (??) m
- L-21 : 1 (or 2), not considered successful
-- L-21 intended to repl. Utva
Čavka gliders
-- 3v:
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/3vues/Letov_L-21_3v.jpg
--
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/photos/Letov-21.jpg
L-22 - 1961 'Libis' 2-seat training glider
- L-22 : Braced high-wing glider, span 16.00 m
- L-22 : Welded steel-tube fuselage, wooden wing
-- aka Letov 22 or Letov L-22, some date '1956'
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2007/04/l_22_pro.jpg
--
https://www.modelarstvo.si/letov-l-22/
--
https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=815
_______________________________________________
Ljubljana - LIBIS Non-Sequential Aircraft Designations
LIBIS 520 - (Project) 1956 light twin monoplane
- LIBIS 520: Low-wing cabin business aircraft
- LIBIS 520: 2 x (??) hp (HO6?), span 10.62 m*
-- Some say 12.72 m,
ing. Marjan Slanovec design
-- 3v:
https://www.modelarstvo.si/wp-content/uploads/2019/11/003_Libis_520.jpg
--
https://www.modelarstvo.si/libis-520/