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LET designations

hesham

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From Czechoslovakia,

Let L-300 :was a six seat version of Morava, a twin engined
light aircraft.
Let E-33 :experimental Morava with T-tail and an engine in
the rear cabin for boundary layer experiments.
Let XL-36 :low wing agricultural aircraft with a belly-mounted
hopper, but was abandoned in favour of Z-37.
 

Stargazer2006

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New topic created from an old post by hesham in a generic topic. Feel free to add to it!
 

hesham

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Later I will speak about;

XL-8,L-03,KT-03,KT-04,E-31,E-32,E-33,L-18,L-208,Z-37,Z-37-2,Z-137,
Z-237 & Z-437.
 

hesham

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Hi,

I confess,here I did some mistakes,and I mixed the products from anther firm,but I will talk about
all Let aircraft list later.
 

hesham

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Hi,

L-145 was initial developed from Aero Ae.45 as amodern version with some improvements,Project
L-110 was a four-seat all metal low-wing light and touring monoplane Project
L-200 Morava was a four-passenger low-wing light and touring monoplane,had retractable tricycle u/c,powered by two 210 hp Walter M337 engines
L-210 or L-201 was developed from L-200,but powered by two 245 hp Walter M338 engines
L-300 was a improved version of L-200,with fully integrated cabin,but later converted into E-33
L-400 was a Project,very resemble to a small Antonov An-24;
L-410 was a high-wing short range medium transport monoplane,powered by two 800 hp General Electric H80-200 turboprop engines
L-410Jet was a jet Project version of L-410
L-420 was a a refined version of L-410,took approval in USA
L-420XXL was based on L-410,as all metal,designed for carrying of 2100 kg bulk cargo
L-430 was a stretch version of L-410 powered by two P&W PT-6 turboprop engines,Project
L-440 ------?
L-450 was the same or later became,L-510P
L-500 was a two-seat low-wing light and touring monoplane,Project,powered by single engine
L-510 was developed from L-500,with Walter M132 engine,Project
L-510/II was a 19-passenger wide body high-wing all metal commuter transport monoplane Project,powered two turboprop engines,mounted in main wings
L-510P was developed from L-510/II,but had two turboprop engines,mounted beside the rear of the fuselage,Project
L-520 was developed from L-500 with Walter M137 engine,Project
L-539 was a 4/6 business jet low-wing monoplane,based on L-39 jet trainer,Project
L-540 was developed from L-500,as a four-seat version,with Walter M338 engine,Project
L-550 was developed from L-540,with Walter M137 engine,Project
L-600 or XL-600 was a low-wing T-tail medium jet airliner monoplane Project,powered by two turbojets,mounted beside the rear of the fuselage
L-610 was a modern version of L-410,powered by two 1750 hp GE CT7-9D turboprop engines
L-610P was a stretched Project version of L-610
L-614 was a four engined version of L-610,Project only
L-620 was a Project developed from L-610,need confirm
L-710 was a Project developed with Fairchild as a cargo aircraft,based on L-410
L-1000 or XL-1000 was a larger version of L-600 airliner,Project only

Later I will add non-standard series
 
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Sarastro

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Hi,
project LET L-410JET from 1966-67. The engine for this aircraft was based on the thermodynamic nodes of the Walter M-601 engine. It was to reach a bypass ratio of 1:14.
Source: L + K Let L-410JET_.jpg Let L-410JET.jpg
 
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hesham

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From L+K,

what was this ?.
 

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Apophenia

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Hi,
LET L-610P+
Source: L + K

I've only just realized that I never posted my Let designation list compiled a few years back. I will post it ... but first a question:

Sarastro: Can you tell me what the difference was between the L-610P and L-610P+. Is the latter a military derivative of the former?
 

Sarastro

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Hi Apophenia,
the LET L-610P + project dates from 2002 and was supposed to be the maximum possible use of the carrying capacity of the original L-610 project. The L-610P + was to have a completely new, redesigned and raised stern, in which a two-part tilting ramp was to be placed. Another change was a significant increase in the capacity of the fuselage by extending it by 6.8 m. The designation L-610P + means "plus" just that extension. The letter "P" then marked the selected engine P&W PW127. The L-610P + was primarily intended to address customers primarily from the military air force, and since the Czech Air Force was looking for a replacement for the An-26 at the time, LET Kunovice assumed that the Czech army might be interested in them. However, the type was not developed only for the Czech Air Force, the main advantage in the sale was to be up to half lower price compared to comparable types.
PS: There was no version of the L-610P, only the L-610P +.
From:L+K
10.jpg
 

Apophenia

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Many thanks Sarastro. Below is my promised stab at Let designations. I'm hoping that you will look it over for any obvious errors. Apologies for the missing Czech accents and diacritical marks (I have the wrong keyboard and language settings for this).

First a bit of background ...

Let Kunovice - Aircraft Designation Styles

To the consternation of non-Czech speakers, the terms Let (Flight) and Letecké (Aviation) were applied time and again as names for the aircraft makers of Czechoslovakia. On-going official renamings of firms in the immediate post-WW2 era doesn't help. Personally, I find the Let factory at Kunovice the most confusing. The first postwar nationalization plan combined aviation works - Let, Avia, Mráz, and others - with automotive plants. Under AZ n.p. (Automobilových závodu), Let became závod 6 Kunovice (or Factory No.6 at Kunovice) or simply 'Z 6'.

In May 1949, závod 6 Kunovice was reorganized as Let národní podnik (Let National Corporation) or Let n.p. Kunovice. But, despite the geographical name, this new organziation included the aviation facilities at Otrokovice and Chocen along with Kunovice. Around the same time, formerly independant design offices were reorganized. Previously designated LT1 through LT5, in 1948 the design office codes were changed to LA through LE. A spin-off from LA formed an LF design group for gliders under the leadership of ing. Vladimír Štros. LG indicated another glider design group from Otrokovice. All of this has a knock-on effect on Let glider designations as we'll see later.

At the end of WW2, Kunovice (originally part of Avia a.s.) was essentially an aircraft maintenance, repair, and overhaul facility. Under the first postwar nationalization scheme, the Kunovice plant became LET n.p. (in all-caps). The Kunovice plant began producing entire aircraft - both under license and aircraft of its own design - which should have lent the name 'LET' some caché. Instead, the name was changed six times between 1949 and 2004. (see next post).

_______________________________________

[1] As noted, n.p. is for národní podnik (State corporation) while a.s. is for akciová spolecnost (Joint Stock Company). Strojírny první petiletky translates as '[Machinery] Works of the First 5-Year Plan'. Letecké závody translates at 'Aviation Plants' which was then Anglicized as Aircraft Industries.

_______________________________________

LET/Let Kunovice Corporate Identities

1948-1949: LET (Letecké závody n.p. or Aircraft Factory, national corporation)
- Tranferred from AZ n.p. to LZ n.p. on 10 September 1948 [1]

1950-1956: Let n.p.

1957-1966: SPP (Strojírny první petiletky, n.p. or [Machinery] Works of the First 5-Year Plan)

1967-1990: Let n.p.

1991-2001: Let a.s.
- Owner: Ayres Corporation

2001-2004: Letecké závody, a.s.
- Owner 1990-2002 Moravan a.s.

2004-201x: Aircraft Industries, a.s. (but originally still operating as 'LET')
- Owner 2002-2006: Moravan-Aeroplanes a.s.
- Owner 2006-2008: Moravan Aviation s.r.o.
- Owner 2008-201x: Ural Mining and Metallurgical Company

_____________________________________________

[1] AZ n.p. was the Automobilovych závodu národní podnik (Automobile Factories, national corporation). LZ n.p. was for Leteckych závodu národní podnik (Aircraft Factories, national corporation). Later incorporation acronyms were a.s. for akciová spolecnost (or public limited company) and s.r.o. for Spolocnost s rucením obmedzenym (or limited liability company).
 

Apophenia

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Designations - 'L' for 'Let' ... Or Not?

Confusing matters for foreign designation list compilers (not least, myself) is the historically widespread use of 'L' designation suffixes in the Czechoslovak aircraft industry. Perhaps this is to be expected with Let meaning 'Flight' (and a host of other flight-related meanings) and Letecké meaning 'Aviation'. But this has resulted in 'L' designations being applied by Aero, Let Kunovice, Let n.p. of Otrokovice (now better known as Zlín), as well as the similar-looking Letov of Prague-Letnany. [1] The L-based designations arising from the previously-mentioned glider design offices tend to confuse matters further.

Gliders designed at Let Kunovice received 'L' designations - such as the famous L-13 Blanik. However, these sailplanes were preceded by a range of gliders with 'LF' designations. As mentioned, the LF gliders design group under the direction of ing. Štros was independent. Many of this group's glider designs were built by Let Kunovice and assigned LF-xxx designations (or XLF-xxx designations for experimental types). But not all 'LF' gliders came from Kunovice. Some 'LF' gliders were built by Letov. Many sources also attribute 'LG'-designated gliders to Let Kunovice but this is a confusion dating back to the Let n.p. of the 1950s which included the Otrokovice plant better known as Zlín (AFAIK, all 'LG' gliders were built by Otrokovice/Zlín).

Perhaps listing known Let Kunovice aircraft designation in one place will reduce some of this confusion by a process of elimination?

Let Kunovice Designation Style Presentation

Despite the on-going name changes listed above, the products of the Kunovice facility are invariably referred to as Let (originally all-caps 'LET', despite not being an acronym). Let Kunovice aircraft designs were assigned an alpha-numeric designation beginning with 'L' (or 'XL' in the case of experimental types and prototypes). [2] Let designation styles and presentation vary. There's the usual space, hyphen, and dot conundrum. I'm sticking with hyphens but you'll see all variations - even in official and corporate sources ... sometimes within the same document. Current corporate usage seems to avoid the space or 'punctuation' ... but not consistently.

Aircraft type designation numbers seem to begin with a straightforward numerical sequence ... albeit, a sequence which appears to commence with the L-13 Blaník sailplane. In this case, '13' seems to have been a lucky number for Let (but, alas, there are still a lot of numerical 'gaps' in my Let listing). [3]

At some point, type designation numbers jump into a 'Century' series. [4] The lowest numerically is the L-110 light plane project from the 1990s. However, 'Century' numbers date back at least to the 1957 L-200 Morava - a contemporary of the L-13 sailplane. It'd be tempting to conclude that the L-200 was assigned simply to emphasize its twin-engines. The number tend to stay within 'hundred blocks' - eg: after the success of the L-410 Turbolet developments are the Let L-420, L-430, and L-450 (albeit, with no sign of an L-440 so far). Follow-on designs stuck to the L-410 pattern with the unbuilt L-510 and aborted L-610 series.

Designation suffixes also vary. Most are straightforward alphabetical sequences for sub-types. Other start out that way and devolve into alternative styles. An example is the L-13 glider range. However, even with the L-13 sequence, there are plenty of oddities. Eg: the L-13 is followed by the L-13B Bacostroj single-seat moto-glider. [5] Then comes the L-13AC aerobatic trainer - where, apparently, the 'AC' stands for ACrobatic. Then, there is a shift to an increasingly complex sequence of distinguishing sub-type designations. Note that the seemingly sequential L-13A doesn't appear until decades later (when Aerotechnik insets this designation for an updated L-13 model).

For the successful L-410 Turbolet series, a similar set of sub-type suffixes were applied. Prototype L-410s had no suffix while PT6A-powered pre-production aircraft were designated L-410A. Similarly-powered sub-types received designation suffixes like 'AB (Harzell propellers), 'AF ('F' for Foto), 'AS ('S' for Sovet), etc. The variant for Aeroflot was designated L-410UVP (an acronym akin to STOL), [6] its VIP Salon version being the L-410UVP-S.

Other Turbolet sub-type designations were obviously adopted for marketing purposes. A dedicated freighter variant with enlarged cargo doors was designated L-410T ('T' for Transport) while the updated Turbolet has been dubbed L-410NG with the ever-popular 'New Generation' tag.

Other anomolous Let sub-type designations were assigned to unbuilt projects. The 'K' in L-39K - a rival to the built Aero L-39 Albatros - simply stood for Kunovice. The 'P' in L-200P - a proposed floatplane variant of the L-200A Morava - stood for Pontoon (Pontoon) while the 'P' in the unbuilt 2002 L-61-P+ transport stood for its intended engine-maker, Pratt & Whitney Canada.

Let Kunovice Engine Type Designation Suffixes

Let engine type suffixes seem to have first been applied to L-13 designations. In the later L-13 sub-type suffix style, 'S' standards for 'Standard' (Standard Type) was then followed by an engine type (or propeller type) designator. Let and Aerotechnik powerplant suffixes were/are: 'J' for 'JAWA' (L-13J); 'TJ' for 'TJ100' (ie: PBS TJ100 turbojet, L-13TJ).

Other Let or Aerotechnik powerplant suffixes are: E for Mikron IIIAE (as in L-13SE); H for Hoffman propeller (as in L-13SEH); L for Limbach (as in L-13SL); M for Mikron (as in L-13SDM); W for Walter (Mikron III). (I'm not sure about the L-13SDL suffix. It may be for 'Dvojník' for Double, referring to the fixed, twin-wheel undercarriage - as opposed to the more usual, retractable single-wheeled unit). For unknown reasons, installing the Rotax 912 in the L-13SE has not resulted in an 'R' engine suffix.

There was also a host of engine-specific sub-type designations for the L-410 but these don't follow a neat pattern. The M-601A-powered model was the L-410M ('M' for Motorlet, perhaps because 'A was already spoken for?). [7] But there was no follow-on 'L-410B' for M-601B-powered sub-types - instead, these the L-410MA and L-410MU. When the Aeroflot variant was given M-601E engines, it became the L-410UVP-E. So far, so good. But a M-601F-powered derivative became the L-410UVP-E20 for no obvious reason (it was designated L-420E which doesn't help - 'L-420F' would have been more consistent).

Below, I will list the Let designations that I know of. Due to gaps and some reuse of designation numbers, I'll break these designation up into more utile blocks.

_____________________________


[1] See the separate section on Letov designations.

[2] A seeming oddity is the E-33 'Konrad', a purely experimental variant of the Morava. But that L-200A was modified by the VZLÚ (Aeronautical Research & Test Institute). Thus, E-33 is part of a separate VZLÚ 'Experimentální' designation sequence (following their unbuilt twin-engined E-31 and tilt-wing E-32 project with twin Turbomeca Astazous).

[3] Some of those 'gaps' may represent internal designations for licensed-built aircraft - such as the Yakovlev C-11 and Aero Ae-45 developments (although the original internal designation for the Ae-45S is known to be L-145). Similarly, internal designations may have been applied to some co-developments (eg: the Z-37 Cmelák co-developed by Let Kunovice and Moravan Otrokovice aka Zlín).

[4] One might wish to conclude that 'Ten' series designs were all gliders while 'Century' series were powered aircraft ... except, one of the earliest known Let projects was for the 1955 L-18, a twin-engined light transport.

[5] There are also retroactive designations - such as L-13A1 applied to the 'Llewellyn Modification' life extension programme. It's not clear to me whether such designation changes were accepted by the makers (Let or Aerotechnik).

[6] The UVP acronym is Russian, standing for Ukorochennaya vzlot-posadka or 'shortened take-off and landing'.

[7] I have assumed that the 'A' in L-410A simply designates a first variant. However, it is possible that this referenced the final letter in the PT6A designation. If so, Let faced a problem when the next engine type - the M-601A ended with the same suffix letter.
 

Apophenia

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Let Kunovice - Non-Standard Designations

Aero Ae-45 - Let-built light twin transport, x 410
- Ae-45 : Aero design, last 20 built at Kunovice*
- Ae-45 : 2 x 105 hp Walter Minor 4-II, span 12.25 m
-- * Prod. moved from Prague to Kunovice in 1951
- L-145: Orig. internal designation for the Ae-45S
- Ae-45S: Super Aero Let improved variant**
- Ae-45S: 2 x 105 hp Walter Minor 4-III, span 12.25 m
-- Ae-45S improv. primarily concerned avionics, x 228
-- Ae-45S built 1954-59, no des. change for ambulance
- Ae-145: Higher-powered, supercharged Ae-45S devel.
- Ae-145: 2 x 140 hp Walter M-332-III, span 12.25 m
-- Ae-145 developed at Kunovice 1959-61, x 162 built

Let C-11 - Let-built Yakovlev Yak-11 trainer, x 710
- C-11: 1953, all-metal rear fuselage unlike Yak-11
-- Soviet Yak-11s had fabric-covered rear fuselages
- C-11: 1 x 700 hp Walter M-21 radial,* span 9.40 m
-- * Walter/MotorLet licensed Shvetsov ASh-21 7-cyl
- C-11U: 1956 tricycle gear development, x 3 (or 4)
- C-11U: 1 x 700 hp Walter M-21 radial, span 9.40 m
-- C-11U had diff. prop, improved radio-nav equip't
-- NB: C-11 was MNO desig., 707 built incl. C-11U**
-- ** Sources vary, Valka.cz says four C-11U built

_____________________________________________________

Let Kunovice - 'LF' Glider Designations

is a glider aircraft developed by Czechoslovak manufacturer Let Kunovice. It was designed as a two-seater training aircraft and the first flight was performed in March 1950.

Let LF-106 - (Project) 194? Single-seat training glider
- XLF-106: Concept abandoned at early stage in design
- XLF-106: Eclipsed, redesigned as XLF-109 Pionýr

Let LF-109 - Pionýr 1950 Single-seat training glider
- XLF-109: Fabric-covered steel-tube fuselage, wood wing
- XLF-109: span 13.47 m, wing area 20.20 m2, x ~470
-- XLF-109 only reached 'pre-project' design phase

Let LF-100 - XLF-100 (Let design?, confusion w/ XLF-110?)

Let LF-110 - (Project) 195? 2-seat high-winged sailplane
- XLF-110: Mixed constr. counterpart to Blaník
- XLF-110: Slight forward wing sweep, span 16.00 m
- XLF-110: Designed by ing. V. Štros & J. Matejcek

Let LP-110 - (Project) 1953 2-seat high-winged glider
- LP-110: All-metal counterpart to L-13 Blaník
- LP-110: 2-piece trapezoidal wing, span ?? m
-- LP-110 design by ing. Karel Dlouhý

Let LF-113 - (Project) 19?? 2-seat high-winged sailplane
- XLF-113: L-13 evol. by ing. K. Dlouhý & R. Mrázek
- XLF-113: Submitted after deadline, develop. abandoned

Let LF-114 - Standard single-seat training glider
- XLF-114: 1956 Standard 15, aka M-16, span 15.00 m
-- Led to 16 m Orlican VT-16 Orlík & VT-116 Orlík II

Let LF-209 - (Project) 1952 2-seat high-winged sailplane
- XLF-209: Slight forward wing sweep, span 15.50 m
- XLF-209: Submitted to Cz, authorities, Fall 1952
-- XLF-209 offered insuff. advantage over Pionýr
-- Sailplane and Gliding, Volume VII, No.3 (June 1956), page 150

Let LF-309 - (Project) 19?? 2-seat high-winged sailplane
- XLF-309: Slight forward wing sweep, span ?? m
- XLF-309: Sim. to XLF-209 but with much longer-span*
-- * With mass balance fairing on end of each wing tip

Let LF-309 - (Project) 19?? 2-seat high-winged sailplane
- XLF-309: Slight forward wing sweep, span ?? m
- XLF-309: Sim. to XLF-209 but with much longer-span*
-- * With mass balance fairing on end of each wing tip

Let LF-409 - (Project) 2-seat training glider
- XLF-409: New wing on a Pionýr fuselage
- XLF-409: Trapezoidal wing planform, span ?? m

Let LF-509 - (Project) 2-seat high-winged sailplane
- XLF-509: Slight forward wing sweep, span ?? m
- XLF-509: Sim. to XLF-209 but trapezoidal wings
_____________________________________________________
 
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Apophenia

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Let Kunovice - 'L' Aircraft Designations (to 99)

Let L-13 Blaník - 1956 2-seat high-winged, all-metal glider
- L-13 : Intitial prod'n model, span 16.20 m
- L-13A : 1981-1982 resumed prod., stronger wings, x 20
- L-13A : Renewed production undertaken by Aerotechnik
-- L-13A1: (Llewellyn Modification) life extension
-- Sportine Aviacija SL-2P: Twin-fuselage devel.
- L-13AC: (ACrobatic) Trainer, shorter 14.20 m wings
-- Combines L-13 tail with L-23 cockpit and wings
-- TG-10C Kestrel ('Saber') 5 x USAFA
- L-13B : Bacostroj single-seat motorized glider, x 1
-- 1 x nose-mounted Walter Mikron IIIA, 48 kW
- L-13J : (JAWA) Motorcycle engine-powered motor glider
-- L-13J : Pylon-mounted JAWA engine above rear fuselage
- XL-13T : (Trabant) motor glider (auto engine conv.)
- L-13TJ : (TJ100) single-seat experimental glider
-- Powered by PBS TJ100 (TJ100A or TJ100C) jet engine
- XL-13M : 1964 OK-6202 motor-glider conv., 1 x Walter A
- XL-13M: Conv. of one of the XL-13 prototypes
- L-13W : (Project) Early '70s motor-glider, Walter Mikron
-- L-13W: Pursued at Aerotechnik L-13SW (below)

-Aerotechnik*-produced L-13 Vivat variants
-- * Now Evektor-Aerotechnik
- L-13 Vivat: Side-by-side seat motor glider tourer
-- aka Aerotechnik L-13 Vivat, var. engines
-- L-13B Vivat: Aerotechnik vers. of Bacostroj
-- L-13SE : Walter Mikron IIIAE, air brakes
-- L-13SE Rotax : As L-13SE but w/ 100 hp Rotax 912
-- L-13SL : Std. model, 1 x 67 hp Limbach L200E01
-- L-13ST : 1 x Tatra AT-714, later conv. to Rotax
-- L 13SV : Common German typo for L-13SW (below)
-- L-13SW : Walter Mikron IIIAE, 3-blade prop
-- L-13SW was later rebranded as L-13SEH Vivat
-- L-13SDL: L-13SL variant with fixed taildragger u/c
-- L-13SDM: As L-13SDL but with Mikron IIIAE
-- L-13SEH: Walter Mikron IIIAE, 3-blade prop
-- L-13SEH is rebranded L-13SW Vivat (qv)
- L-113 : (Project) 1957 simplified Blaník
- L-113 : L-13 without flaps or retractable u/c
- L-213 : (Project) 1957 long-span Blaník
- L-213A: 1992 aerobatic glider using L-13 parts
- L-213A: Dev. begun 1982, moved to Shempp-Hirth Chocen

Let L-14 - L-17: (??) hypothetical designations

Let L-18: (Project) 1955 twin-boomed, light transport a/c
- L-18: Sesquiplane wings, clam-shell door for pod
- L-18: 2 x 700 hp Walter M-446 IV-12s,* span 28.00 m
-- * One prototype to have 2 x Alvis Leonides Major
-- * Future plans for 2 x 700-850 hp M-481 radials
-- L-18: Main u/c retr. outwards into lower wings**
-- ** Optional skis or twin pontoon float gear
-- 2v: https://www.gonzoaviation.com/AwEsh...ry/618/muska_Let_l_18__20140610_101905331.jpg

Let L-19 - L-20: (??) hypothetical designations

Let L-21: 1957 Spartak single-seat sailplane
- L-21: High-winged, span 18.0 m, glide ratio 38.0
-- L-21 Spartak proved not a great performer
-- Complaints of tight cabin and poor cockpit view

Let L-22: (??) hypothetical designation

Let L-23 Super Blaník - 1988 2-seat glider
- L-23: L-13 deriv., 2-piece canopy and a T-tail
- L-23: High wing, span 16.20 m,* area 19.20 m²
-- Wing tip extensions available, span 18.20 m
-- aka L-23 Standard, prototype aka X-01
-- Prod'n series L-23s built 1989-2006, x 300
-- TG-10B Merlin: L-23 for USAF Academy, x 12
- L23NG : (Project) New Generation by Blaník Aircraft CZ sro
-- L23NG: Revised w/ wingLets, impr. fuselage, single canopy
-- http://www.blanik.aero/l23ng-3

Let L-24 - L-32: (??) hypothetical designations

Let L-33 - Sólo 1992 single-seat sailplane
- L-33: Shoulder-wing, span 14.12 m, area 11.00 m²
- L-33: Intended for trans. from L-13/L-23, x 100+
-- TG-10D Peregrine: L-33 for USAF Academy, x 4

Let L-34 - L-35: (??) hypothetical designations

Let L-36 - (Project) Low-wing agricultural aircraft
- XL-36: Belly-mounted hopper, abandoned for Z-37

Let L-37 - L-38: (??) hypothetical designations

Let L-39K - (Project) 196? 2-seat military jet trainer
- L-39K: Rival Let design to Aero L-39 Albatros

...
______________________________

Let Kunovice - 'L' Aircraft Designations (from 100)

Let L-110 - (Project) 1995 4-seat low-wing light a/c
- L-110 : Single-engined, all-metal constr. monoplane
- L-110 : Deriv. from Family-Air design for LOK*
- L-110 : To use Family-Air parts & subassemblies
-- * Letecke Opravny Kbely, former state-owned MRO firm**
-- ** Sep. Family-Air, spol. s ro formed on 09 Sept 1993

Let L-113 - (Project) 1957 simplified Blaník
- L-113 : See L-13 without flaps or retractable u/c
...

Let L-145: Orig. internal designation for Ae-45S (qv)
- L-145: Marketed as the Ae-45S Super Aero
-- NB: L-145 is not the same as supercharged Ae-145
...

Let L-200 Morava - produced 361 planes in 1957-1964.
- L-200: Low-winged twin-engined, twin-fin light a/c
- XL-200: 1st prototype (aka XL-001, OK-LNA) flew 09 April 1957
- L-200 : 2nd prototype (aka XL-03, OK-LNB), becomes E-33
- L-200 : Pre-production series (for CSA & CzAF), x 10
- 2 x 160 hp Walter (MotorLet) Minor 6-III, span 12.31 m
- L-200A : 1960, 2 x 210 hp MotorLet M-337, span 12.31 m, x 150
-- L-200A had 2-blade electrically-adjustable V 410 props
- L-200B : (Project) L-200A evol., abandoned for L-200D
- L-200C : (Project) UK airworthiness cert'd L-200A
- L-200D : 1961, 2 x MotorLet M-337Š, span 12.31 m, x 39
-- L-200D engines had 3-blade constant-speed V 506 propellers
- L-200 Libis: L-100D CKD kits supplied to LIBIS, Ljubljana
- L-200P : (Project) Ponton, twin-float L-200A deriv.
-- Cantilever struts to mate 6.38 m floats to nacelles
-- 3v: https://www.gonzoaviation.com/AwEsh...lavakova_morava_vykres_20140527_041524581.jpg

-- E-33: Experimental Morava with various tail types*
-- * Cruciform tail (in photos), T-tail also mentioned
-- E-33 fitted w/ 2nd engine** for boundary layer exper.
-- ** 1 x 325 hp Walter M-108DHK driving M-42's blower
-- ** Dorsal intake for M-108DHK was above rear cabin
-- https://www.secretprojects.co.uk/threads/Letov-aviation-plant-wolfsberg-projects.11242/#post-278940

Let L-201 - Orig. (alternative?) desig. for L-210 (OK-PHB)

Let L-210 - 1966 6-seat L-200D* Morava derivative
- L-210 : Mod. & re-engined L-200D, x 1 conv. (OK-PHB)
- L-210 : 2 x 245 hp MotorLet M-338, span 12.31 m
-- * 5th pax seat centred behind central rear backrest
-- L-210 not certified, reconv. to L-200D in early '70s

Let L-213 - 1957 long-span Blaník, realized as L-213A
- L-213 : (Project) 1957 aerobatic glider, not pursued
- L-213A: 1992 aerobatic glider using standard L-13 parts
- L-213A: Dev. begun 1982, moved to Shempp-Hirth Chocen

Let L-300 - (Project) 1958 L-200D Morava turboprop deriv.
- L-300 : Slightly-enlarged 9-11-seat air-taxi L-200 devel.
- L-300 : 2 x 690 shp Walter M601B turboprops,* span 11.34 m
-- Pressurized fuselage, 2 x wing configurations considered
- L-300D: (Dolnoplošník) Low-winged config., pilot + 8 pax
- L-300H: (Hornoplošník) High-winged config., pilot + 10 pax
-- See description/3-view in reply #24 by Sarastro
-- * Prod. M601B shp; L-300D 3-view shows Turbomeca Astazou

Let L-400 - (Project) 196? turboprop feederliner study
- L-400: Twin-turboprop, high-winged, 12 pax transport
- L-400: 2 x 900 shp Turbomeca Astazou, span ?? m
-- Said by Jaroslav Dostál to resemble H.P. Herald

Let L-410 - Turbolet twin-turboprop transport, ~1,200
- L-410: Light transport for Soviet & domestic requir.
- L-410: Orig. design from a line of studies/projects
- L-410 : 1965 (Project) Studies for Antonov An-2 repl.
- L-410 : 1969 high-wing, turboprop transport, retr. u/c
- XL-410: 1st prototype, flew 16 April 1969, aka L-410
- L-410 : Prototypes (x 3), 2 x 715 shp P&WC PT6A-27s
- L-410 : Slightly shorter/less span than prod. L-410A
- L-410 : No.1 had 3-bladed Hamilton-Standard props
- L-410 : Nos.2 & 3, quieter 4-bladed Hartzell props
- L-410A: 1971 prod., 2 x 715 shp P&WC PT6A-27s, x 12
- L-410A: 2 x 715 shp P&WC PT6A-27s, span 17.48 m
- L-410AB: 2nd prototype L-410A, 4-blade Hartzell props
- L-410AB: Displayed at 1971 Le Bourget Paris Air Show
- L-410AC: Common typo for Soviet eval'n L-410S (qv)
- L-410AF: 1974 aerial survey type, glazed nose, x 1
- L-410AG: 4th prototype, UK BCAR airworthiness stds.
- L-410AM: Vers. w/ M601Bs, same as L-410MA (qv) or L-410MU
- L-410AS: Trials aircraft, supplied to the USSR, x 5
- L-410FG: 1985 aerial survey variant for CzAF, x 6
- L-410FG: Glazed nose, 2 x 740 shp Walter M-601D
-- https://www.valka.cz/attachments/1945/L410FG1526_1.jpg
- L-410M: 1973, 2 x 735 shp* Motorlet M601A, x 109
-- * Many sources list 740 shp for Motorlet M601A
- L-410M: 17 pax East Bloc model, Avia V 508A props
- L-410MA: 1973, 2 x 760 shp M-601Bs with V 508B props
- L-410MA: Alternative des. (or typo?) was 'L-410AM'
- L-410MU: 1978, auto roll-control vers. for Aeroflot
- L-410UVP: 1977 shorter take-off vers. for Aeroflot
-- UVP = Ukorochennaya vzlot-posadka or STOL
- L-410UVP: Lengthened (0.86 m), longer span (19.48 m)
- L-410UVP: 3 prototypes/1st series, Motorlet M-601Bs
- L-410UVP: 1983 2nd series, M-601Ds w/ V 508D props
- L-410UVP: 2 x 690 shp Motorlet M601D, span 19.48 m
- L-410UVP: 0.86 m longer/+2.01 m span/tail dihedral
-- L-410UVP offered as 15 pax/freighter/6+5 medevac/
-- 14 paratroop/12 fire control/photogram/navaid, etc.
- L-410UVP: (Project) Mid-'80s trimotor deriv., unbuilt
- L-410UVP-E: 1986, 750 shp Motorlet M-601E, span 19.48 m
- L-410UVP-E: 5-blade Avia V 510 props, wingtip tanks
-- NB: 'UVP-E sub-type mods have run from 'E1 to 'E20
- L-410UVP-E1 : (no details)
- L-410UVP-E3 : 1989, M-601Es, pilot/navigator trainer
- L-410UVP-E4 : (no details)
- L-410UVP-E8 : (no details)
- L-410UVP-E9 : Equipment changes for Western markets
- L-410UVP-E10: (no details)
- L-410UVP-E13: (no details)
- L-410UVP-E14: (no details)
- L-410UVP-E15: (no details)
- L-410UVP-E16: (no details)
- L-410UVP-E17: (no details)
- L-410UVP-E18: (no details)
- L-410UVP-EA : (no details) poss. confusion with 'E4
- L-410UVP-EZ : Pilot/navigator trainer w/ 'E20 upgrades
-- Currently 2 x GE H80-200/AV 725 props as per L410NG
-- NB: Walter M-601H-80 development became GE's H80
- L-410UVP-EZ : Poss. conf. w/ 'E3 or z (follow)
- L-410UVP-E20: 2008 Westernized vers., US FAR-23 stds.
- L-410UVP-E20: Certified as the L-420E (below, qv)
- L-410UVP-S: (Salon) VIP UVP, upward-hinged cabin door
- L-410UVP-V: 1986 'Vstavka' stretched, 22 pax L-410
-- Vstavka translates from Russian as 'insert'
- L-410UVP-V: 2 x 775 shp Motorlet M-601F, span 19.48 m
- L-410UVP-V: Prototype only, not put into production
- L-410T: Transport 1982, CzAF, enl. cargo door**
-- ** Door measures 1.25 m x 1.46 m, 1,000 kg containers
- L-410T : Alt., 12 paratroops or 6 stretcher medevac
- L-410(??): (Project) Simplified L-410 concept for Soviets
- L-410(??): 12 pax, mod. fuselage, T-tail, fixed u/c
- L-410(??): 2 x ??? shp Glushenkov TV-10s, span ?? m
- L-410(??): (Project) Single-engined L-410 deriv.
- L-410(??): Nose turboprop, fixed undercarriage
-- Intended as Let Kunovice's rival to Aero Ae-270
- L-410NG: (New Generation) 2015 L-410 update variant
- L-410NG: 2 x 800 shp GE H80-200s,*** span 19.48 m
-- *** H-80s are updated M-601s, 850 shp for prod'n
- Ayres LM-200 Loadmaster: Utility w/ L-410 parts

Let L-420 - (Project) 196? study towards Turbolet
- L-420 : (1) Commuterliner study led to L-410
- L-420 : 2 x ?? shp Turbomeca Astazous, span ??

Let L-420 - (Project) 198? cargo variant of L-410
- L-420 : (2) Dedicated cargo-carrier Turbolet
- L-420 Cargo: Dedicated cargo-carrier Turbolet

Let L-420 - 199? Westernized L-410 Turbolet deriv.
- L-420 : (3) 17-to-19 pax, US certification May 1998
- L-420 : (3) 2 x 775 shp Walter M-601F, span 19.98 m
- L-420 Cargo: Freighter, Fairchild/FedEx co-venture
- L-420E: 'E' for Extended (referring to the nose)
- L-420E: Certified as L-410 UVP-E20, 2 x Walter M601Fs
- L-420 XXL: Stretched L-410/L-420 Cargo development

Let L-430 - (Project) 199? stretched L-410 devel.
- L-430: 2 x ??? shp P&WC PT6A-?? turboprops, span ??
-- L-430 to be highest TOW variant of L-410 family

Let L-440 - (??) hypthetical designation

Let L-450 - (Project) 199? Let L-410 replacement a/c
- L-450: L-410 development or replacement project
- L-450: Alt. desig. for L-510P (Jaroslav Dostál)
-- Most closely resembled orig. 'L-410 replacement'
-- Above suggests an earlier design phase of L-510

(To be continued ...)

_____________________________
 
Last edited:

Apophenia

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Let Kunovice - XL-5x0 series 'L' Aircraft Designations

The 1962-1965 Let XL-5x0 series all-metal light aircraft family concepts are grouped here:

Let L-500 - (Project) Low-wing 2-to-4-seat tourer
- XL-500: 1962 studies for a range of light a/c
-- XL-500 to employ some XL-542 (qv) components
- XL-500: 1965 more detailed 2-seater concept
- XL-500: 1 x 120 hp Walter M-132 L4, span 9.87 m

Let L-510 - (Project) 1965 low-wing 2-seat trainer
- XL-510: Elementary trainer,* fixed tricycle gear
- XL-510: 1 x 120 hp Walter M-132 L4, span 9.87 m
-- * Fully aerobatic, designed for lower costs
-- One-piece, forward-sliding cockpit canopy

Let L-520 - (Project) 196? low-wing 4-seat tourer
- XL-520: Higher-performance* variant of XL-510
- XL-520: 1 x 180 hp Walter M-137 L6, span 9.87 m
-- * IFR, glider tug, aerobatic with pilot only

Let L-530 - (??) hypothetical designation

Let L-540 - (Project) 1965 low-wing 4-seat tourer
- XL-540: Higher performance, retr. trike u/c
- XL-540: 1 x 235 hp Walter M-338, span 9.87 m
- XL-540: Featured side doors (vs. sliding hood)

Let L-550 - (Project) 1965 low-wing 4-seat tourer
- XL-550: Economy model of XL-540 with fixed u/c
- XL-550: 1 x 180 hp Walter M-137 L6, span 9.87 m
- XL-550: Basic VFR instrumentation only

_________________________________________________________

The Let 'L' numerical sequence resumes below ...

Let Kunovice - 'L' Aircraft Designations (continued)

Let XL-500 - XL-550 light planes (see above)

Let L-510 - (Project) 1992 twin-turboprop commuterliner
- L-510 : (2)* High-winged, 19-pax pressurized a/c
-- * Desig. chosen to suggest an L-410 replacement
-- * Duplicate designation of 1965 light a/c project
- L-510 : 2 x 1,100 shp P&WC PT6A-65B, span 16.74 m
- L-510P: Rear-mounted pusher turboprop arrangement**
-- ** Akin to Embraer/FMA CBA 123 Vector prototypes
- L-510P: 'L-410 replacement' design phase, aka L-450

Let L-539 - (Project) 19?? single-engined business jet
- L-539: Based on Aero L-39 Albatros components
-- https://www.secretprojects.co.uk/threads/Letov-aviation-plant-wolfsberg-projects.11242/

Let L-542 - (Project) 196? twin-engined light a/c
- XL-542: no details

Let L-600 - (Project) 1964 twin-jet feederliner a/c
- XL-600: See Non-Sequential 'L' Designations (below)

Let L-610 - 1988 twin-turboprop medium transport a/c
- L-610 : Planned East Bloc rival to DHC-8 & ATR 42
-- * Designation chosen for its association with L-410
- L-610 : 2 x 1,822 shp Walter M-602, span 25.60 m
- L-610 : x 8 (6 flying, 2 for structural testing)
- L-610(??): (Project) 1982, 2 x P&WC PT7A/PW100*
-- * In response to problems and delays with M-602
-- * Also see L-614 with 4 x Walter M-601Es below
- L-610M: Retro. desig. for M-602-powered L-610s
- L-610M: 'M' for Motorlet (Walter after 1995)
- L-610M: 2 x 1,822 shp Walter M-602, V 518 props
- L-610G: 1992, 2 x 1,750 hp GE CT-7-9Ds engines**
- L-610G: 'G' for engine maker, General Electric
-- ** Driving four-bladed HS 14 RF-23 propellers
-- Ayres 7000: Export re-designation for L-610G***
-- *** aka Ayres L-610 (but Ayres went bankrupt)
- L-610MPA: (Project) L-610G-based maritime patrol
- L-610(??): (Project) Stretched vers. of L-610G
-- 50-55 seater, powered by GE CT7 or P&WC PW100
- L-610P+: (Project) 2002 rear ramp and raised tail
-- L-610P+ intended as an An-26/An-32 replacement
- L-610P+: 2 x P&WC PW127 turboprops, stretched
-- Length 28.20 m (vs 21.70 m), also + 0.2 m span

Let L-614 - (Project)* 1982 4-engined L-610 deriv.
- L-614: 4 x Walter M-601E turboprops, span 25.60 m
- L-614: Altern. to problems and delays with M-602
-- * 20% of work performed before return to L-410

Let L-710 - 1993 'Boxplane' joint-project w/ Fairchild
- FL-710: FX Freighter concept based on L-610G components*
-- * Wings, engines, empennage, main u/c (now fixed), etc.
- FL-710 6FX : 6 x LD-3 containers in rectangular fuselage
- FL-710 6FXT: 6 x LD-3 containers, large freight doors
- FL-710 8FX : 8 x LD-3 containers, with rear cargo ramp**
-- ** And other changes (unspecified by Jaroslav Dostál)
-- Prototype flown as (??)

________________________________________________________________

Let Kunovice - Non-Sequential 'L' Designations

Let jet airliner projects were assigned non-sequential designations with type numbers based upon their maximum ranges. The first design was the more ambitious L-1000, followed by the less risky L-600.

Let L-1000 - (Project) 1963 Smaragd jet airliner
- XL-1000: Swept-wing, T-tailled 40-to-48 pax jetliner
- XL-1000: 2 x 2845 kg (TO) RD-22DP, span ?? m
-- Desig. based on av. range,* eclipsed by XL-600
-- * Range to be speed-dependent 850 to 1,200 km
-- XL-1000 to be operated off of 2,000 m runways
- XL-1000: 24 pax (850 mm pitch) with 600 km range
-- The word smaragd translates as 'emerald'

Let L-600 - (Project) 1964 twin-jet feederliner a/c
- XL-600: Meant as Lisunov Li-2 repl. (as Yak-40)
- XL-600: Straight wings, rear-mounted jet engines
- XL-600: 2 x 1850 kg turbojets, span ??
-- Desig. based on max. range, eclipsed XL-1000
-- XL-600 to be operated off of 1,000 m runways
- XL-600: Straight wings, rear-mounted jet engines
- XL-600: 24 pax (850 mm pitch) with 600 km range
- XL-600: 30 pax ( ?? mm pitch) with 450 km range

____________________________________________________________
 

hesham

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Amazing work dear Apophenia,

but L-18 and E-33 were belonged to VZLU.
 

Apophenia

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Thanks hesham. As I mentioned in one of my footnotes, the E-33 'Konrad' was an L-200A airframe modified by the VZLÚ (the 'E' being for 'Experimentální'). I included the E-33 in the designation listing for completeness, since it was derived from the Morava.

The L-18 brings up a good point. When is a Let not a Let? One online sources is titled Let L-18 / 1955 while artwork on that page clearly reads "VZLÚ-1955". FWIW, attached drawings are marked "VZLÚ KL-Ae" ... although I have no clue what that 'KL-Ae' stood for.

Other pages reproduced begin with a generic "VZLÚ Konstrukce letadel". Okay, so that assures us that this was not simply a design exercise - VZLÚ intended this aircraft to be constructed. But by whom? VZLÚ built many prototype airframes but it was not this Research Institute's role to series produce aircraft. [1]


__________________________

A few other VZLÚ designs (or designs often attributed to VZLÚ) are:

VZLÚ (Vyzkumny A Zkusebni Letecky Ústav, Aeronautical Research & Testing Institute)

VZLÚ XL-160 - 1957 Aero L-60 Brigadyr development, x 1

VZLÚ HC-2- 1955 Heli Baby 2-seat utility helicopter, x 23

VZLÚ HC-3 - 1960 2+3-5 seat multi-purpose light helicopter, x 5*
- HC-3: 1 x 215 hp M 108H, 270 hp M 108DH, or 295 hp M 108DHK
-- * Non-flying XHC-3M, 1 x static test, 3 x flying prototypes

VZLÚ HC-103 - (Project) Increased-power HC-3 development, unbuilt

KT-03 - 19?? high-winged, tailless towed target for MiG-15T
- KT-03: Flat-sided fuselage, strut-braced high wings
-- MiG-15T - T for Tahač (tractor or tug)
-- KT-03 was given the military designation C-02B
-- https://commons.wikimedia.org/wiki/File:VZLÚ_C-02B_pic1.JPG

KT-04 - 1971* mid-winged, tailless towed target for L-39V
- KT-04: All-metal construction, diameter 0.5 m, span 5.30 m
- KT-04: Towed take-off on trolley, parachute landing
-- * KT-04 development may have begun 1969 at Rudy Letov

To that list can be added a host of prototypes sometimes attributed to VZLÚ.

Sojka - Twin-boom pusher-propeller target drone/recce UAV
-- In fact, VZLÚ merely supplied propellers to maker LOM Praha s.p.
-- Czech museums use 'VZLÚ Sojka' mixed with a/c markings [2]

L-208 : 1956 Letov 2-seat tandem military trainer, x 1 prototype*
- L-208: 1 x 235 hp Praga Doris C (M-208-C) HO6, span (??) m
-- aka Letov L.8, aka TOM-8 (after Ing. Karel Tomas)
-- Once again, a prototype (XL.8?) built by VZLÚ for Letov [3]

One example is the L-208 prototype - aka TOM-8 (after chief of design, Karel Tomáš) or Letov L.8. Obviously, in this case, it was Letov which was to series build this military trainer if accepted.

__________________________

[1] Eg: VZLÚ HC-2 Heli Baby with VZLÚ building 2 prototypes while series production was by Moravan n.p. at Otrokovice.

[2] At least, that's what I assume is going on with 'designations' like PE-80 Sojka VM-4 andSojka E.50. Or, perhaps, those fit the 'missing' numerals leading up to the Sojka 3 (aka Sojka III)?

[3] Some time back - in the Letov Designations section - hesham mentioned an "XL-8". I'm pretty sure that was yet another designation for the Letov L.8 prototype (as built by VZLÚ).

__________________________

Perhaps Sarastro can further clarify the role of VZLÚ as a service supplier to series producers like Letov, Let, LOM, et al?
 

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Hi,
the study of the LET L-300 aircraft dates from 1958 and was originally intended to be powered by M-601B turboprop engines developed at VAAZ Brno. However, the development of these engines dragged on, and so the project was stopped. Two configurations were considered - low-wing L-300D for the pilot and eight passengers, max. speed 390 km / h, and high-wing L-300H, ten passengers, max. speed 350 km / h. Both variants were to have a pressurized cabin. The M-601B engine had an output of 420 hp. The project was tested on models of both variants in the VZLÚ wind tunnel.
From: My archive
Let L-300D.jpg Let L-300D_0.png
 

Apophenia

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Excellent stuff Sarastro! That adds both sub-type letters and specification details to our L-300 entry :)

The engines are a puzzle. Obviously the Motorlet M601B was intended (and those were late even for the L-410 series of a decade later). The thing is, the engines on your 3-view drawing don't appear to be reverse-flow turboprops like the M601. They look much more like 'straight-through' Turbomeca Astazous (which would be more in fitting with that 1958 dating).

If the depicted engines are indeed Astazous, are we potentially dealing with yet another L-300 sub-type designation?
 

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