Let L-410 Turbolet – Flying Flagship

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An L-410UVP Turbolet seen in flight in 2017 over Pardubice, Czech Republic.

Flying the Flag, Far and Wide 

The Czech Republic has a remarkably colourful history in aviation that dates to before the first Czechoslovak aircraft company, Letov, was founded in 1918. The small nation has given the world a wide range of capable aircraft in categories including aerobatics, agriculture, general aviation, gliders, trainers and transports among others.

As Czech aircraft manufacturers go, Let is a relatively young company. Founded in 1936 in the south eastern Czech town of Kunovice, Let started as a maintenance branch of the much older Avia company. It would not be until after the Second World War that Let would come into its own as a company after the Communist government that took over the former Czechoslovakia in 1948 nationalized the contry’s industries. It was at that point in time that Let was split from Avia and made into a separate company.

In April of 1969, the prototype of a new aircraft rose from the Kunovice runway into the air for the first time. Designated the XL-410, it was the beginning of a long lived family of transport aircraft that would grow to not only serve as the flagship product of the Let company for over five decades, but also a global symbol of Czech prowess in aircraft design: the L-410 Turbolet.

Upon first impressions, the L-410 Turbolet may seem nothing more than one of the many twin turboprop powered commuter aircraft types out there. Its unassuming appearances belie an aircraft of robust construction, remarkable flexibility, cost effectiveness and short take of and landing (STOL) performance that few aircraft in its class can match.

Still in production five decades after its first flight, used by air arms and civilian operators in over 70 countires across five continents and still going strong; the L-410 is without a doubt the most succesful of Czech aircraft.

Let’s spend some time with the L-410 Turbolet:

The first XL-410 prototype “Matylda” seen preserved at the Kunovice Air Museum. Kunovice, Czech Republic, 2020.

A Hard Act to Follow 

From the outset, the Turbolet was intended to be a very self-sufficient aircraft that could operate in extremes of temperature and from rough or completely improvised airstrips in very remote regions. These specifications were arrived at as one of the aircraft the L-410 was designed to replace was the venerable and legendary Antonov An-2.

The Antonov An-2 is in the history books as the largest single engine biplane ever put into production. Being a biplane first flown after World War Two, the An-2 was something of an anachronism when it was introduced. However, the aircraft had a very unique set of flying characteristics that would make the job of any aircraft intended to replace it a very high order indeed. The An-2 was an extremely self-sufficient aircraft noted for its tough-as-nails construction and STOL performance that has been next to impossible for any other fixed wing aircraft to match.

While the Turbolet certainly has never been able to equal the An-2’s STOL capabilities, in its STOL optimised form it does possess the performance to give it a place among a small handful of aircraft in its class that are capable of operating from the Tenzing-Hillary Airport in Lukla, Nepal.

Tenzing-Hillary has a long standing reputation as one of the most demanding and dangerous airports for any aircraft and pilot to operate from. This comes from the high altitude the airport is situated at, its short runway length and the unforgiving mountainous terrain that surrounds the airport. Any aircraft and pilot must hold special certifications to fly into and out of the airport. Along with the DeHavilland Canada DHC-6 Twin Otter and the Dornier Do-228 from Germany, the Turbolet is among those few aircraft in its class to be certified for operations from this airport.

The third prototype XL-410 “Zuzka” seen preserved at Kunovice, Czech Republic in 2020.

As with its nearest contemporary designs, the Turbolet is built relatively low to the ground with its wing set high on the fuselage. This configuration allows good access to critical areas of the aircraft for servicing while still allowing maintenance crews to stand on the ground or require nothing more advanced than a basic stepladder to do their jobs. The configuration also allows for easy loading of cargo or passenger boarding as no specialized airstairs or cargo lifting machinery are required to load the aircraft.

Certified to operate in temperatures that range from -50C (-58F) to 50C (122F), there are very few environments on Earth where the Turbolet would be unfit to work.

With a take off run of around 510 metres (1,673 feet) and a landing run of around 500 metres (1,640 feet) in its STOL optimised versions, there are very few places in the world the Turbolet could not get into or out of.

Early production Turbolet variants seen preserved at Kunovice, Czech Republic in 2020.

A Bit of East and a Bit of West

Studies for the aircraft that would become the L-410 started in the 1966-1967 timeframe. In the same period of time, the domestically designed Walter M601 engine that would eventually power the L-410 was under development.

From the outset, the aircraft was designed as a short haul machine that could carry between 12 and 19 passengers or 1850 kg (4079 pounds) or cargo into or out of a wide variety of airport and runway types. The aircraft was designed to operate from airstrips made of grass, sand, gravel, clay or snow at rudimentary airfields with equal ease as it would operate from a well prepared asphalt runway at a fully equiped airport.

The reason for designing this level of versatility into the aircraft was to ensure it had a chance of meeting specifications put forth by the former Soviet Union for a new aircraft requirement of the state airline, Aeroflot. The airline needed a modern, well built, durable and dependable aircraft to replace the older types they had to serve the communities on their more remote routes.

The former Soviet Union was the world’s largest nation, a distinction that contemporary Russia still holds today. Outside of the major cities, there are wide tracts of less developed areas with far flung communities that can only be reached with aircraft. Typically, these regions have climates that are harsh and unforgiving on man and machine alike. Needless to say, the bushflying art is alive and well in these remote corners of the world.

The turbolet met the specifications and many of the type were exported to the former Soviet Union and quickly gained popularity among those who worked with it. It still enjoys a good deal of popularity in Russia.

The Walter M601 engine, versions of which powered all but the earliest Turbolet variants.

While the former Czechoslovakia was solidly within the Socialist sphere of influence at the time the Turbolet was being developed, there was a western component to the prototypes and earliest production versions in the form of the Pratt and Whitney Canada PT6 engine.

The choice of the PT6 came about from the fact that the Walter M601 would not be ready for flight at the time the prototype Turbolets would be completed, so a substitiute engine was required to make sure the prototypes got airborne on schedule. The PT6 was a proven engine that was a close match for the sort of performance the M601 would provide later versions of the Turbolet.

Let also considered Garett engines from America and Turboméca engines from France before settling on the PT6.

An L-410MA, an example of the second production series, seen at Kunovice, Czech Republic in 2013.

Refining the Machine

From the first flight of the XL-410 in April of 1969, it was clear that the Turbolet would be a solid performer and worthy of further development. However, as it is with all machines, the prototype and production versions can differ quite a lot.

This is a general overview of the Turbolet family development across major production models:

XL-410

The prototypes of the Turbolet line were designated as XL-410. Three XL-410 prototypes were built, the first and third were flying prototypes while the second was used for stress testing.

L-410A

The first production series of the family was the L-410A. Like the prototypes, aircraft of this series were powered by the PT6 engine.

The L-410A line differed from the prototypes by having a completely redesigned main landing gear as well as structural reinforcements nose to tail. Other differences included a small stabilizing fin being added to the underside of the rear fuselage as well as changes to the propellers and aircraft de-icing system.

A total of 31 aircraft were made to L-410A standards. Significant among them was the L-410AS, a specialized version for the Soviet Union that proved the Turbolet’s excellent performance in climatic extremes and rudementary airport and airstrip conditions.

L-410M

The second production Turbolet series, the L-410M, debuted in 1973 and is the series that defined the Turbolet family on the world stage.

The L-410M was the first series of the family to be powered by the Walter M601 engine. Most of the development that took place between versions of the M model concerned the fitting of improved versions of the M601.

An L-410UVP seen operating on a grass airstrip in Prague, Czech Republic in 2016.

L-410UVP

An offshoot of the L-410M, the L-410UVP is different enough to be considered the third production series of the Turbolet family.

While all members of the aircraft family are capable of STOL performance, the UVP versions were optimised to bring those qualities of the aircraft to the fore.

The UVP versions had more powerful engines as well as increases to the wingspan and tail area. All of this was to meet a STOL specification set out by the Soviet Union. While the UVP met the specification, it turned out to be a machine of compromises.

The increases in wingspan and tail surface area translated into an increase in overall weight in the UVP versions and corresponding decreases in performance as far as payload, range and economy of operation were concerned.

Beyond the basic UVP version, this branch of the family includes:

L-410UVP-S: VIP transport version with an executive interior fitted.

L-410UVP-E: Improved version with more powerful engines, five bladed propellers and wing tip fuel tanks.

L-410T: A cargo optimised version with a larger cargo door.

L-410FG: A specialised version with a glass nose for aerial mapping and survey work.

The first L-410NG prototype seen at Kunovice, Czech Republic in 2018.

L-410NG

Debuting in in 2015, the L-410NG “New Generation” is at once a member of the Turbolet family and a substantial departure from what has gone before it in the lineage.

The NG was developed from the UVP-E and maintains the spacious passenger cabin the aircraft family is known for as well as the robust construction and mission flexibility.

Where the NG differs is in a redesigned wing that allows for more fuel to be carried and has resulted in a significantly increased range for the NG model. The NG also can carry more cargo in a lengthened nose and has a fully modern cockpit and avionics suite.

Additionally, the NG has more powerful engines from General Electric. In fact, the new engines are a development of the M601 and bear General Electric branding due to the Walter company becoming subsidiary to General Electric in 2008.

The L-410NG has been in series production since 2018.

A Czech air force L-410FG seen at Ostrava, Czech Republic in 2015.

Flexing to Function and Fun

As mentioned in previous sections of this article, the Turbolet was designed with a good amount of mission flexibility in it. This is thanks largely to its spacious cabin area.

Beyond standard passenger and cargo variations, the cabin can be fitted with air ambulance or emergency medical service interiors. It can also be fitted with an executive interior for VIP or corporate flying.

Along with the roomy cabin, the L-410 has the power and range to make it useful for aerial survey and mapping work as well as patrol and surveillance work. Special modifications for aerial mapping and photogrammetry created the L-410FG version with its distinctive glass nose.

The flexibility of the Turbolet was further tested in Russia in 2017 when experiments were carried out to test the type’s suitability for ski and float landing gear.

It’s not all work and no play for the Turbolet. The aircraft is very popular worldwide as a platform for skydiving. With a good climb rate and the roomy cabin, it lends itself very well to getting larger groups to jumping height efficiently.

If you’re a more intrepid holiday maker who looks for more exotic and remote locales to visit, you may very well find yourself on a Turbolet for at least part of your journey. As mentioned earlier, the Turbolet is one of the few aircraft types of its class that could get you to Nepal’s Tenzing-Hillary Airport.

A Czech air force L-410UVP seen at Náměšť nad Oslavou, Czech Republic in 2012.

Come aboard, It’s Perfectly Safe

In some quarters, the Turbolet has been branded an unsafe aircraft. However, this is quite unfair and borders on the ridiculous.

The fact that more than 1,200 examples of the Turbolet have been built over the years and it’s still in production more than five decades after it first flew is testament to the soundness of the design and the competence of its designers.

On the surface, it would seem the Turbolet is an accident prone machine. It’s been involved in over 100 accidents that have resulted in over 400 fatalities. However, before one judges the accident record of an aircraft like the Turbolet, one must keep in mind a few things about it:

A vast majority of accidents the Turbolet has been involved in were traced back to human error rather than any issues inherent to the design of the aircraft.

Very few aircraft can operate in places where the Turbolet can and many of those places are inherently risky to fly in even for the most rugged of aircraft and most seasoned of aircrew. Accidents are bound to happen in such places even under the most ideal of circumstances.

Turbolets are often operated in developing or underdeveloped nations where regulations are poorly if at all enforced. That in combination with many operators of the aircraft being small and remotely located has often lead to poor quality control in both ground maintenance and aircrew training.

An L-410UVP-E seen at Kunovice, Czech Republic in 2018.

The L-410 Today and Learning More

While some Turbolets have found their way into museums, the type is still very much an active flyer earning its keep in air arms and on civil registers worldwide. As such, your chances of seeing one in action aren’t particularly scarce.

Without a doubt, the best place to see the bulk of the Turbolet family line in one place is Kunovice, in the south east of the Czech Republic. Kunovice airport is home not only to the Let company, but also the Kunovice Air Museum. The museum dedicates most of its activities to preserving the aviation history of Kunovice. In the museum collection, you will find the first and third XL-410 prototypes as well as early production Turbolet models. A visit to Kunovice could also see you in a position to watch resident Turbolets operating at the airport.

Still in production more than fifty years after it was designed, the Turbolet shows no signs of slowing down any time soon.

This link will take you to a website with a wealth of information on all aspects of the Turbolet and its development. The site is in Czech, but responds well to online translator functions.

These links will take you to pages about the L-410UVP-E and L-410NG at the Let website.

Medlánky Oldtimers Weekend – 2020 Edition

September 5 and 6 of 2020 mark the annual Oldtimers Weekend at Medlánky airfield in Brno Czech Republic.

The weather was beautiful and there was a good selection of vintage sailplanes and general aviation aircraft on view.

With the COVID crisis of 2020, many famous airshows around the world have been cancelled, including a couple I regularly attend here in the Czech Republic. I’m very happy that the Medlánky Aeroklub didn’t cancel their Oldtimers Weekend this year. It’s likely to be the only airshow I get to see this year.

I’ll just let the pictures speak for themselves and show you the atmosphere of the day:

Extra 300 – The Rhine Roller

An Extra 330 LT at Brno, Czech Republic in 2020.

The Push for More 

Aerobatics is a category of flying that has been with us in one form or another almost as long as powered flight. Perhaps this should be no surprize as humanity has always seemed to have a fixation of not only driving the technology we create forward, but also pushing what we create to its very limits. As far as civilian aviation is concerned, specialist aerobatic aircraft may well be the ultimate expression of that drive.

Competition level aerobatics exists at four main levels: Sportsman, Intermediate, Advanced and Unlimited. Aircraft designed with the Unlimited class in mind are highly specialized machines indeed, with little if any consideration given to any type of flying outside of top tier aerobatic competition when designing them.

An aircraft of the Unlimited class sacrifices nearly everything else in the pursuit of combining high thrust with low weight that will allow the aircraft to perform all the required moves for the class and yet not tear the aircraft apart in the process.

Needless to say, an aircraft of the Unlimited class is not one for the novice pilot. Indeed, any pilot that advances as far as the Unlimited class will have amassed hundreds of hours of flying hours before reaching that level. They will also be a very physically fit individual quite worthy of being seen as a top level athlete.

The Extra 300 first flew in 1988 and became an iconic machine in the Unlimited category through the 1990s. Let’s spend some time with it:

An Extra 330 SC seen at Pardubice, Czech Republic in 2019.

An Insider’s Knowledge 

The Extra 300 was created by Walter Extra (1954-), an award winning aerobatics pilot from Germany who created his own aircraft company in 1980. The Extra Aircraft company is located near the Rhine river in the town of Hunxe, in the North Rhine-Westphalia state of Germany.

Beyond being a decorated aerobatics pilot, Walter Extra also is qualified as a mechanical engineer. The impetus to create his own aircraft company was to create a machine fit for the Unlimited class that would be an improvement on the aircraft by other designers that he had been flying up to that point. His experience as a competitive pilot and his professional engineering qualifications ensured that he could achieve that goal.

The first aircraft developed by Extra Aircraft was the Extra 230 which first flew in 1983. While the Extra 230 was the direct ancestor of the Extra 300, one needs to go back rather further to see where the Extra 300 lineage really starts.

The Extra 230 and 300 are extreme developments of the Stephens Akro, an American aerobatics design from the late 1960s. While quite rudimentary compared to the Extra designs, the Stephens Akro was a popular and successful design that could be homebuilt and lent itself well to modification.

What links the Stephens Akro to the Extra designs is the Akro Laser Z-200, a one-off modification of the Akro that won a number of aerobatics championships between 1975 and 1982 in the hands of American pilot, Leo Loudenslager (1944-1997).

The Akro Laser Z-200 served as the basis for the Extra 230 design. The Extra 230 was fairly conventional in design, featuring a tube steel frame fuselage with wooden wings. A refined version of the 230 was created and called the Extra 260, though very few were ever made.

The Extra 230 was a very popular and successful aircraft that was produced from 1983 to 1990 and set the stage for the watershed event that the Extra 300 would be to the aerobatics world.

Extra 300 SR in flight at Pardubice, Czech Republic in 2019.

The New Standard 

The usual desires for reduced weight and increased power that drive competitive aerobatics also primarily drove the leap from the Extra 230 to the Extra 300. However, it was rather more than just competition in the air that led Extra to create the machine that would become their flagship product for three decades.

Materials and manufacturing processes figured very prominently in the evolution of the 230 to the 300. While the 230 had some carbon fibre composite structures in it, the 300 would include much more composite materials in its structure. Significant among these was the wing of the 300, which was of fully carbon fibre composite construction as opposed to the plywood wings of the 230.

While the plywood wings gave the 230 light weight, the material itself was maintenance intensive and difficult to control the quality of. Walter Extra was having difficulty finding plywood of a suitable quality to make wings from and so made the decision to make the wings of the 300 from carbon composites. The dividends of this decision were enjoyed from the factory all the way to the end users of the aircraft

The first advantage of switching to composite materials was that quality control was much easier right from the start. Carbon composite was a much more predictable material than plywood and this reduced the amount of testing time required for each individual aircraft leaving the factory. The predictability of the composite material also reduced manufacturing time as factory workers assembling the aircraft didn’t have to worry about the sort of variability plywood could have from one piece to another.

For the end user, that same predictabilty resulted in reduced inspection and maintenance time which resulted in reduced operating costs. The composite wing also gave the desired weight savings as it was lighter than plywood. An additional benefit the composite wing gave to the end user was a substantial increase in structural strength that allowed for higher performance in competition.

Another advantage the Extra 300 came with was that it was designed as a two seat aircraft from the start. For an Unlimited class aerobatics aircraft to have two seats as an option is a very unusual thing and the two seat option made the Extra 300 attractive to flying schools that offered aerobatics courses as well as experience rides.

While nobody could ever accuse the Extra 300 of being an aircraft for the novice, it is known as a pilot friendly aircraft for its class and the two seat option makes it easier and quicker for a pilot to learn and master the 300 than some of its contemporaries.

The qualities of the 300 have given it popularity in team as well as individual aerobatics. There are a number of civilian aerobatics teams around the world that use the 300 to perform while the military air demonstration teams of Chile, Jordan and Malaysia all use the 300 as their mount.

Extra 330 SC and 300 SR seen at Pardubice, Czech Republic in 2019.

The Extra 300 Family 

Since its first flight in 1988, the Extra 300 has seen more design evolution than perhaps any other aircraft in its class. For an Unlimited class aerobatics aircraft design to have lifespan of three decades and still be in production and competitive is truly a remarkable thing and testament to the drive of the designers to keep pushing for more from it.

Another unusual aspect of the 300 is that it has demonstrated an adaptability to other flying categories that some of its contemporaries in the Unlimited class have not. While always having aerobatics at the heart of the design, the 300 has also been adapted to air racing and touring.

As of mid 2020, almost 800 examples of the 300 had been built across a dozen variants and sub-variants:

Extra 300/300 S

The Extra 300 was the baseline two seat model of the 300 family. The aircraft took its name from the 300 horsepower Lycoming engine that powered it.

The Extra 300 S is a single seat development of the baseline 300 that also features a reduced wingspan and improvements to flight controls.

Extra 330 SX and Extra 300 SP/SHP

The 330 SX was a more powerful development of the 300 S that included a 330 horsepower engine and larger control surfaces on the tail. A number of 300 S models were refitted with the larger rudder of the 330 SX.

The 300 SP was a variation of the 300 S that had reduced weight and the 330 SX rudder fitted to it.

The 300 SHP was a higher performance variant of the SP.

Extra 300 SR at Pardubice, Czech Republic in 2016.

Extra 300 SR

The 300 SR was a version fitted with a wing optimised for racing. Most specifically, it was designed for the Red Bull Air Race series that ran from 2003 to 2019.

Extra 300 L/300 LP

The Extra 300 L is the most produced of any member of the 300 family. It’s a two seat variant with the wings set lower on the fuselage than previous versions. The repositioned wing had no effect on the aerobatic qualities of the aircraft, but did make entering and exiting the aircraft easier for the pilot.

The 300 LP was to the 300 L what the 300 S was to the baseline 300; a weight reduced version with higher performance for competition flying. As of 2020, the 300 LP is still in production.

Extra 330 SC/LX/LT

The Extra 330 SC was developed to replace the 300 SP and 330 SX. It’s a single seat competition level aircraft with an improved roll rate over previous members of the aircraft family. The 330 SC really is the ultimate development of the Extra 300 design as pilots flying it have won the biannual World Aerobatics Championships five times: 2009, 2013, 2015, 2017 and 2019.

The 330 LX is a two seat version of the SC.

The 330 LT is a development of the LX that is aimed at touring. Retaining most of its aerobatic abilities, the LX includes a baggage compartment and has all the required cockpit instruments and avionics required for longer cross-country flying.

As of 2020, all three of these versions are still in production.

Extra 330 LE

First flown in 2016, this was a fully electric powered single seat version powered by a Siemens engine. In 2017, it set new speed records for electric powered aircraft and became the first fully electric powered aircraft to tow a glider aloft.

Extra 300 S at Vyškov, Czech Republic in 2012.

The Extra 300 Today 

In 2019, Extra debuted their Extra NG, a fully new aerobatics machine that will hopefully prove a worthy successor to the Extra 300 legacy.

With a lifespan much greater than most aircraft in its class could hope to have, around 800 produced and still more being made along with a healthy demand for the type on second hand markets; the Extra 300 family is far from flying into the proverbial sunset.

Still a top notch performer in competitions and a reliable crowd pleaser at airshows, your chances of seeing a member of this aircraft family being put through its paces are far from remote.

Learning More

This link will take you to the official website of Extra Aircraft:
Official website of Extra Aircraft

This link will take you to an article from Pilot magazine that will give you an feel for what the Extra 330 LX is like from a pilot’s perspective:
Extra 330 LX article at Pilot magazine website

This link will take you to the website of Belgian aerobatics pilot, Kristof Cloetens. It’s a good “Voice of experience” type website that will give you insights into the life of an aerobatics pilot as well as judging criteria for competitions and so forth:
Link to Kristof Cloetens’ website

Acknowledgement:

I would like to extend thanks to Mr. Christian Hochheim of Extra Aircraft for providing me with extra information that filled some blanks I encountered while doing research on this article.