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Let L-610 for the Soviet Aeroflot: a beautiful plane with a sad history

Let L-610 for the Soviet Aeroflot: a beautiful plane with a sad history
The initial impetus for the development of the Let L-610 high-wing turboprop was a bilateral agreement between the relevant ministerial bodies of Czechoslovakia and the USSR, signed in 1976. Kunovice's "410" model aircraft have already proven themselves even in the worst natural conditions, accommodating up to 17 passengers (first version, later increased to 19 seats).

After this, the customer requested the development and subsequent delivery of a slightly larger machine for domestic flights. Initially there was talk of a passenger capacity of 30 people, then it was increased to forty. In fact, this was the best alternative to the old Soviet Yak-40 and An-24 aircraft, which would eventually be replaced on Aeroflot routes by the new L-610.

Let L-610 для советского «Аэрофлота»: красивый самолет с печальной историейEngines of the Let L-610 aircraft. Photo: youtube.com

The development of the L-610 itself, before the very first prototype flew, proved to be very thorny. As for the power plant, a pair of new M602 turboprop engines from Motorlet (formerly Walter, now GE Aviation Czech) was expected from the very beginning.

Since their release was also delayed, work began on a four-engine version with the already improved smaller M601, used since 1975 on the production L-410. By the way, the situation smacked of deja vu: the first few dozen “400s” were equipped with Pratt & Motors Whitney Canada PT6, because the manufacturer was also late with the development of the M601.

Finally, the first flight

The four-engine L-610 was created during design work, according to the same principle as twin-engine aircraft. The first to be designed was a non-flying model with a wooden frame and “cut off” outer parts of the wing on a 1:1 scale. And then changes came.

Passenger lounge in L-610. Photo: youtube.com

Despite the fact that the Soviet side approved the development of such a version, even before the start of assembly work (three years later), they returned to their wishes for a twin-engine vehicle. Let's explain what this meant: the huge amount of design work done on the primary project simply went to waste. But the customer is always right, and the engineers began to move in the newly indicated direction.

Finally, on Wednesday, December 28, 1988, after a long development with some changes to the technical characteristics, the first L-610 prototype took off with the OK-130 test register. The crew included: first pilot and commander Frantisek Srnec from the Kunovice team, second pilot Stanislav Sklenarz and aircraft technician Josef Sterba.

A number of design revisions required the utmost care from the team. Therefore, during the test flight without passengers, the crew carried parachutes as a precaution, but they were not needed. The twenty-minute first flight, to the general satisfaction of all participants, passed without any incidents. It seemed that the 610 would soon be successfully put into production, conquering the Eastern European skies, but... No one knew then that the future would not bring anything good to the new aircraft.

Technical side of the project

At first glance, the new aircraft had many similarities to the smaller L-410 (high-wing character lines with "pockets" in the lower fuselage to hide the main landing gear). But a noticeable difference was the T-shaped tail (much higher horizontal than that of the 410). And here it is worth remembering what is hidden from the eyes of an outside observer. The new product received a pressurized fuselage and built-in fuel tanks in the wing (the same as the L-410NG modification). Let us pay attention to other indicators of Czechoslovakian technology:

✅ maximum capacity – 40 passengers (plus – 2 crew members)
✅ technical weight – 8,95 t
✅ takeoff weight - 14,5 tons
✅ wingspan - 25,6 m
✅ length - 21,72 m
✅ height - 8,19 m

In total, they managed to create six prototypes of the original version, four of them flightable, with M602 engines, and two non-flight ones, intended for destructive (second copy) and fatigue (fourth) tests. The sixth option, by and large, can be characterized as the first production car, originally intended for Aeroflot.

He even flew for some time with the designation of this company, without having anything to do with it, because the issue of the acquisition hung in the air. And not surprisingly, the beginning of the 90s turned out to be a very difficult time, when there was no time for any new projects and updates to the flight fleet. Then a great many promising projects were buried. The aircraft we are considering now, unfortunately, is also one of them.

Let L-610: cockpit with avionics. Photo: youtube.com

The next two prototypes were created in a different era, so they received American General Electric CT7-9D engines. For this reason, they decided to assign a new type designation to the aircraft: L-610G. It is logical that previous vehicles with M602 engines were now additionally labeled as L-610M. Here are the characteristics of the two versions of the aircraft (in brackets is the version with the CT7-9D engine):

✅ power – 1360 (1446) kW
✅ propeller – Avia V518 (HS 14 RF-23)
✅ maximum (cruising) speed - 490 (438) km / h
✅ flight ceiling – 10,25 km

If the project is successfully implemented, this equipment would become the largest Czechoslovak-built aircraft. But a number of insurmountable obstacles stood in her way. The first negotiations with the Americans on the topic of engines for the L-610 took place in the fall of 1990. The next day they became politicized and reached a bit of a dead end. But it is precisely this direction that would ensure the future for the L-610 in conditions when the CMEA and its main participant, the Soviet Union, collapsed.

The shocks, accompanied by a change in the economic situation, meant the loss of a key customer, for whom the L-610 with M602 engines was developed. And even if Russia’s interest in purchasing the aircraft remained, it would definitely be in much smaller quantities than previously planned.

Rear fenders L-610. Photo: youtube.com

The first of the L-610G prototypes was built at the end of 1992. A year earlier, the company had already experienced a fairly significant wave of layoffs, and a dark cloud of bankruptcy hung over Kunowice. The second and last, slightly modernized, prototype was released only in 1997. In addition to American engines, these cars had a number of other features:

✅ Hamilton Standard four-blade propellers
✅ higher vertical tail area
✅ Western avionics

However, there was still no sign that mass production would ever begin. The business was on the verge of survival. To save it and the L-610 project, an investor was attracted in 1998 - the American Ayres Corporation. But this was a dubious success, because this company never developed its own type of large aircraft, but only produced and improved something like the old S-2 from Snow Aeronautical.

Unfortunately, very soon Ayres itself went bankrupt in America. In the meantime, this occasional owner of LET Kunovice managed to rename the second prototype Ayres 7000 and send it to the USA. Here he ended up at the airport near Albany in Georgia, where he is still rotting. Periodically, someone “borrowed” some of its parts, and in the end the plane got the role of the main statistician in the emergency training center.

The promising model hung in the air, waiting for the next bankruptcy of the plant in 2004. Therefore, the Let L-610 project was finally closed in 2006, and all the equipment was destroyed. Fortunately, the enterprise itself was saved. It was renamed Aircraft Industries and since 2013, the Ural Mining and Metallurgical Company has become its sole owner.

Let L-610: front view with lights (very similar to a smile). Photo: youtube.com

In 2019, the Russian side, represented by Deputy Minister for Aviation Industry Development Oleg Bocharov, stated that it was ready to purchase the existing documentation for this aircraft model. The possibility of resuming the L-610 project for domestic transport needs was considered. But it seems that in the current situation it is still difficult to talk about the successful implementation of these plans.


Photos used: youtube.com

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