A website for Preserved Aircraft of All Eras
Today I took an afternoon walk around Medlánky airport and noticed a very unusual glider in action: A Letov LF-107 Luňák.
The Luňák is a Czech design from the late 1940s; only 75 were made and a very small handful remain flying.
Here’s few shots from today:
Feeding the Flame of Success
The Let aircraft company is one of the younger players in Czech aviation history. Founded in 1936 in Kunovice as a division of the much older Avia company—which itself was then a division of Škoda Works—Let quickly found its place in the industry.
Following the Second World War and Socialist take over of the former Czechoslovakia, Let was nationalised. This allowed the company to become a designer and manufacturer of its own aircraft rather than producing for others.
Let is still based in Kunovice, in the southeast of the Czech Republic. Since 2022, it has been under the ownership of the Prague-based Omnipol Group, a major importer and exporter of defence and aviation products in both the Czech Republic and the former Czechoslovakia.
Despite its relative youth among Czech aircraft manufacturers, Let has given the small nation some of its most successful designs. Chief among them is the L-13 Blaník sailplane.
The L-13 was a resounding success at home and abroad. It was widely exported and over 3,000 were built between 1958 and 1978. This makes it the most-produced sailplane of the post–Second World War era, and one of the most-produced sailplanes in history.
Only a few years after L-13 production ended, momentum grew to create a new and improved version to carry the Blaník legacy forward.
That improved aircraft would take shape as the L-23 Super Blaník, let’s spend some time with it:
Striking Hot Iron
By the mid-1980s, there was strong interest in reviving sailplane production at Kunovice
For Let, it was a matter of staying active in the sailplane business. The company had other aircraft, but the L-13 Blaník had been its only glider design in several years, and production of that type had ended. Given the great success of the L-13, it was certainly in Let’s interest to build on it and maintain its reputation in that sector of aviation.
Other forces pushing for an improved Blaník included Omnipol and Svazarm. At the time, Omnipol held a complete monopoly on the import and export of aircraft in Czechoslovakia. The L-13 had been a highly reliable product for them, generating many satisfied customers, so it was very much in Omnipol’s interest to have an updated version to offer.
Svazarm, which existed from 1951 to 1990, was an organisation that promoted cooperation between the civilian population and the military. It provided military-style training in a number of disciplines, including flight. The L-13 was a major training type within Svazarm, and the organisation also encouraged development of an improved variant.
A Tall Order
Improving on the L-13 Blaník was no easy task. It was an immensely popular aircraft with many advantages.
At its heart, the L-13 was a training glider of primarily metal construction, renowned for its resilience to hard landings and other novice pilot mistakes. It also had a semi-retractable main landing wheel that helped protect the fuselage if a pilot forgot to lower it before landing.
The L-13 was also known for its affordability and cost-effectiveness. As fibreglass and other high-maintenance composite materials became the norm in sailplane construction, a simple, tough, metal design like the Blaník still had strong appeal.
Whatever changes were made, what made the Blaník the Blaník had to be preserved.
In the spring of 1986, a team was assembled to design and produce the improved version. The new variant first flew in May 1988 and entered full production in 1989 as the L-23 Super Blaník.
Building a Better Blaník
As with the L-13 before it, the L-23 was primarily of metal construction and retained the semi-retractable main landing wheel. The main areas of improvement, aside from handling, were ergonomics, safety, and weight reduction. These goals drove substantial redesigns of the tail, forward fuselage, and wings.
Tail redesign
The tail was completely reworked. The vertical fin was swept back, and the horizontal stabiliser was moved from the base of the fin to the top.
This higher position made the stabiliser less vulnerable to damage during rough-field landings. It also allowed the component to be built as a single piece, simplifying both its construction and its attachment to the aircraft.
Another improvement at the tail was replacing the L-13’s metal skid with a swivelling tail wheel, making the aircraft far easier to handle on the ground.
Wing redesign
The L-23’s wing was also substantially changed. Designers deleted the wing flaps, which the L-13 had but were rarely used in practice. This made the L-23 wing lighter and simpler, though the trade-off was reduced aerobatic capability compared to the L-13. However, the modifications improved handling at higher speeds.
The large metal wingtip skids of the L-13 were replaced with much lighter fibreglass structures containing small wheels. Like the tail wheel, these improved ground handling.
Later-production L-23s could also be fitted with optional wing extensions, which improved efficiency and glide performance.
Forward fuselage redesign
Up front, the focus was on pilot comfort and visibility.
The cockpit was slightly roomier than that of the L-13, with improved seating, including a seat that could be ballasted to compensate for lighter pilots.
The canopy and sill were redesigned to extend farther downward than the L-13’s, giving the pilot better outward visibility. Later-production aircraft also featured reduced canopy framing, which improved visibility further.
The canopy was divided into two sections: the front hinged sideways, and the rear hinged upward and backward. This made the sections lighter and easier to manage, and also made entry and exit from the rear seat more convenient.
The Super Blaník’s Place
While the L-23 Super Blaník was every bit as rugged a trainer as the L-13, it never achieved the same production run. About 300 L-23s were built between 1989 and 2007.
A major factor in the smaller number was the fall of socialism in Europe in 1989, which brought financial challenges and ownership changes to Let.
Additionally, by the time the L-23 reached the market, more modern sailplanes were available. The L-23 was a worthy heir to the L-13, but ultimately it was a modification of an older design, and flying clubs often chose newer models when budgets allowed.
Even so, the L-23 has enjoyed popularity with those who fly it, and it has been exported to roughly 30 countries. Among its operators is the United States Air Force Academy, where it is known as the TG-10B Merlin.
The L-23 also gave something back to the Blaník family. In the late 1990s, the concept of an aerobatics trainer within the lineage took shape. The result was the L-13AC, which first flew in July 1997. It inherited some of the L-23’s modifications: its wing was a shortened, modified version of the L-23’s, and it shared the L-23’s forward fuselage, though with a one-piece canopy.
The L-23 Today and Learning More
With about 300 built and exports to some 30 countries, the L-23 remains a workhorse, and many are still flying today.
Since 2014, the type certificates for all Blaník-family aircraft have been held by the Prague-based Blaník Aircraft company. As such, ongoing support remains available to keep the type in the air for years to come.
Nostalgia also plays a role in keeping the Blaník family alive. Many pilots around the world learned to fly in an L-13 or L-23 and hold fond memories of them. Within the sailplane community, these aircraft are very much considered “classics.”
To learn more about the L-23 and its place in the Blaník lineage, a good first stop is this article on the Orlita.net website. It covers the entire aircraft family in detail; the L-23 specific part starts halfway down the page. It’s all in Czech, but responds well to online translators.
This week is the end of an era as the Polish air force retires the last of its Sukhoi Su-22 fleet.
The Su-22 is an attack aircraft produced by the former Soviet Union. It entered service with the Polish air force in 1984.
The retirement of the Polish Su-22 fleet marks the end of Su-22 operations in Europe.
It’s an aircraft I didn’t get a chance to see much of in action. By the time I relocated from Canada to the Czech Republic in 2004, Czech air force Su-22s were in museums.
These are pictures I took of Polish Su-22s at the 2013 and 2022 editions of the AirPower air show in Zeltweg, Austria:
June 21 and 22 of 2025 saw the annual Letecký Den (Air Day) event at Břeclav, Czech Republic take place.
It was a great show, the weather could not have been better and there was a good amount of variety and action to take in.
The show had some of the regular performers as well as some newcomers to keep things fresh
Here’s some of my pictures for the Saturday show:
The Pardubice Aviation Fair is an annual event that takes place in Pardubice, Czech Republic. the 2025 edition of the show took place on June 7 and 8. I attended the June 7 show.
It was a pleasantly varied show with a lot of vintage aircraft with some modern in the mix.
We had scattered rain throughout the day, so photogaraphy was a challenge, but I managed to get some presentable shots.
Wings of Self-Sufficiency
The Czech Republic has a long and rich aviation history that reaches back to the early days of flight and predates the independence of former Czechoslovakia from Austria-Hungary in 1918.
The newly emergent nation had a ready and able talent pool of highly skilled professionals from a variety of technical disciplines and hit the ground running from the moment it was established as a free and sovereign state. This should come as no surprise as Czech and Slovak technical prowess was a driving force behind much of the Austro-Hungarian Empire’s industrial and military might.
The Škoda Works of Plzeň, for example, was founded in 1859 and was the largest arms manufacturer in Austria-Hungary at the outbreak of the First World War. Another example was the Vítkovice iron and steel mill established in Ostrava in 1828. Vítkovice was the most important iron and steel producing facility in Austria-Hungary as well as being a major producer of armaments for the empire until the end of the First World War.
As Czechoslovakia was a fully landlocked nation, it should also come as no surprize that developing a domestic aviation industry was an early priority. Letov was founded in 1918 and was the first Czechoslovak aviation company.
Initially founded as Air Arsenal, a state run repair and servicing facility for the foreign aircraft that made up the Czechoslovak army’s aviation arm, Air Arsenal quickly came into its own as a designer and manufacturer of aircraft. Air Arsenal was renamed to Main Aviation Workshops before the Letov name was finally put on it in the mid 1920s.
Letov was a strong performer in the interwar period with a prolific output of aircraft designs in both civilian and military categories.
As with all companies in the former Czechoslovakia in the Second World War, Letov was forced to support the German War effort. The company was used as a repair facility for Geman military aircraft and a production facility for the Junkers Ju 290 aircraft.
The last aircraft fully designed and built by Letov was the LF-107 Luňák glider which first flew in 1948. After the Communist takeover of the Czechoslovak government in 1948, Letov was tasked strictly with producing components for aircraft made by other manufacturers.
Letov still exists today and has been a subsidiary of French based Groupe Latecoere since 2000. Currently, Letov makes components and structures for civilian aircraft from Airbus, Boeing, Dassault and Embraer.
Letov can lay claim to the first domestically designed and mass produced Czech military aircraft, The Letov Š-1. The Š-1 first flew in 1920 and was followed soon after by the updated Š-2 version.
Nearly 100 examples of this aircraft family were built and stood as testament that the new nation was capable of supplying its military with a competent, homegrown aircraft to defend its skies.
Let’s spend some time with the Letov Š-1 and Š-2:
Getting off the Ground
The Letov Š-1 did not have an easy start, and could easily have never existed at all if sceptics in the Czechoslovak military had their way.
In the formative years of the Czechoslovak military air arm, there was a great deal of debate regarding the ability of domestic aircraft companies to supply aircraft to the military that were competitive with foreign designs.
The military favoured foreign suppliers, particularly France. The French government and French aircraft companies were quite eager for the opportunity to supply aircraft to the Czechoslovak military. In fact, a number of French aircraft types served in the nation’s military in the interwar period; examples included the SPAD VII and XIII fighters along with a fleet of Bloch MB.200 bombers that were license built in Czechoslovakia by the Aero and Avia companies.
In the face of military scepticism, the various domestic aircraft producers rose to the challenge and began designing aircraft that would serve military interests.
There was a lot of national pride on the line. The Czechs and Slovaks had just come out from under centuries of Habsburg rule and were eager to show the world that they were capable and competent of being a self-sufficient and modern nation in every aspect, including national defense.
Design work began on what would become the Š-1 in 1919, with the prototype taking to the air for the first time in April of 1920. The aircraft was intended to fill the light bomber and reconnaissance roles. Shortly after the first flight, the military ordered five aircraft for trial purposes.
In autumn of 1920, a more refined prototype was exhibited to an international audience in Prague. This served notice to the world at large that the aviation industry of Czechoslovakia was a competent one and not to be overlooked as a potential supplier of aircraft.
Soon after that exhibition, the Czechoslovak military placed an order for 50 of the new aircraft.
Not Perfect, but a Start
The new aircraft, initially designated as Šm-1, was an ambitious design for the time.
While it was a biplane, as was still common for the timeframe, the Šm-1 was constructed completely from wood. This contrasted with many of its contemporaries that still incorporated large areas of cloth covering on wood frame in their construction.
The fuselage of the aircraft was perhaps the most notable aspect of the design as it was made from molded plywood construction. It was a construction method most famously associated with the World War Two era DeHavilland Mosquito from Great Britain, but was very unusual in the immediate post World War One period.
While the molded plywood construction method gave the Šm-1 a strong fuselage that was more durable than traditional cloth on frame construction, it made the aircraft unpopular with ground crews and maintenance personnel. Repairing damage to the wooden fuselage was more complex and took longer than with the cloth on frame types the crews were more familiar with.
Pilots were also not fond of the aircraft as it had issues with directional stability, so was a challenge to fly. Despite several attempts by Letov to remedy the stability problems, they were never overcome.
In spite of the above problems, the Šm-1 and its descendants succeeded in showing that the Czechoslovak aircraft industry was up to the task of providing aircraft to the nation’s military that were of a modern standard.
Only the engines and armaments of the aircraft were of foreign origin. Early variants were fitted with a six cylinder Hiero engine of Austrian design, while later variants used a six cylinder Maybach engine of German origins. Both early and later versions featured a British designed Vickers machine gun for the pilot and a ring mount for a pair of American designed Lewis guns for the observer.
In the light bomber role, the aircraft could carry two 50 kilogram bombs or twelve 10 kilogram bombs. It could also be fitted with a camera for reconnaissance work.
The Šm-1 and its descendants formed a small family of aircraft comprised of two main variants, the engine fit being the main point of differentiation:
Šm-1/Š-1
The Šm-1 and Š-1 are the same aircraft. The difference came from a change in the Czechoslovak military designation system, where the Š-1 designation replaced Šm-1 in 1923.
These early versions of the aircraft were fitted with a six cylinder Hiero L engine of around 230 horsepower. A total of 28 examples of the Š-1 version were made.
Š-2
The Š-2 designation was used for later aircraft that were fitted with a six cylinder Maybach Mb.IVa engine of around 260 horsepower. The change of engines was due to the Hiero L engine being out of production and in very short supply. By comparison, the Maybach engine was plentiful and easy to accquire.
The Maybach engine brough a modest improvement in the aircraft’s performance, but came with its own set of drawbacks. The main issue was that the Maybach Mb.IVa was optimised for use on airships rather than conventional aircraft. To make it work on conventional aircraft, the engine needed a number of adjustments made that added further challenge to flying the aircraft, such as very sensitive throttle and carburetor controls.
A total of 64 examples of the Š-2 version built; fellow Czechoslovak aircraft company, Aero, license built 40 of them.
The Mind Behind the Machine
Alois Šmolík (1893-1952) was the man behind the design of the Letov Š-1. An aeronautical engineer and business man, Šmolík was the chief designer and technical director of Letov from its establishment until he left the company 1943.
Šmolík’s interest in aviation showed while he was still a student at technical school. He build his first glider in 1910 and his first powered aircraft in 1913.
He joined the military in 1913 and was wounded in late 1914 while serving on the Russian Front. After being wounded, he was reassigned to Vienna and tasked with organizing the design department of the Austro-Hungarian air force. He also spent some time building his knowledge of aeronautics through study at the Vienna Institute of Technology.
Šmolík returned home to Prague after the war and helped to establish the state run Aviation Arsenal, which would eventually be renamed Letov.
Under Šmolík’s watch, the company flourished and produced a remarkable number of aircraft types, some of them seeing significant production runs for the time period.
Aside of the Š-1 and Š-2, important Letov designs from the interwar period included:
Alois Šmolík left Letov in 1943. As German occupation forbade any design and construction of Letov’s own aircraft in favour of the company servicing German needs, there was nothing to keep Šmolík there. He moved his family to Příbram, south-west of Prague, and spent the rest of his life in non-aviation related work there.
What Remains and Learning More
The interwar period was a time of remarkably quick advances in aeronautics. For aircraft from a newly established nation in that timeframe, the Letov Š-1 and Š-2 did well for themselves.
In spite of their shortcomings, nearly 100 were built and they served the Czechoslovak military from 1920 to 1926 before being gradually replaced by more modern domestic designs, such as the Aero A.12 and A.11.
Only one example of this aircraft family remains intact to the present, an Š-2 that is part of the excellent Kbely Aviation Museum collection in Prague, Czech Republic.
This specific aircraft was removed from service in 1926 and ordered to be scrapped in 1928. Happily, the aircraft was spared and taken into the collection of the Military Museum of the Czechoslovak Republic.
The aircraft was moved to the National Technical Museum’s care in 1935 and remained in their collection until it was transfered to the Kbely museum in 1979.
A large scale restoration of the aircraft began in 1983 and concluded in 2003.
Further Reading
To learn more about the Letov Š-1 and Š-2, a good start would be to visit the dedicated articles about the types on the Československé Letectví and vinar.cz websites. Both articles are written in Czech, but respond reasonably well to online translator functions.
You can also visit this page at the Czech Military historic Institute’s website. It contains general information about the Š-1 and Š-2 as well as more detailed information about the Š-2 preserved at the Kbely Aviation Museum. This article is also in Czech, but works well with online translator functions.
Pickled Wings 