"Cheburashka"! The strengths of the rare AN-72 aircraft, whose engines are located above the wings
The planes produced by the Soviet Antonov design bureau were distinguished by an unusual design, the author of the article notes. He tells about one unique aircraft of the "family" of An, which in Japan was compared to a character in a popular Soviet cartoon.
Can take off and land on a runway only 600 meters long?
The planes produced by the Soviet Antonov design bureau, and now by the Ukrainian company of the same name, are distinguished by an unusual design, which at that time was rarely seen in Western countries.
The most famous is the AN—225, the world's largest aircraft, which was destroyed during the fighting in Ukraine, but the AN-72 transport, whose engines are mounted above the wings, is no less unique.
The design of the AN-72 began in the mid-1970s, and the first flight took place in 1977. A total of 114 aircraft were built from 1984 to 1992. Despite its unique shape, the AN-72 is relatively small in size from the point of view of a jet transport aircraft: its length is approximately 28 meters, and its width is 32 meters.
The AN-72 belongs to the category of so-called shortened take-off and landing aircraft. It was designed in such a way as to be able to take off and land on a 600-meter-long runway, the level of training of which is lower than standard.
The essence of the fuselage design is that the short landing gear is attached under the fuselage, and not to the wings or engines, in order to facilitate cargo loading and ensure unhindered boarding and disembarkation of passengers.
The rear doors open to the left or right. But the most unique is the location of the engines. This is another of the strengths of the aircraft and one of the innovations aimed at improving the characteristics for a shortened take-off and landing.
Advantages of engines mounted above the wings
The layout of the AN-72, in which the engines are located above the base of the wing, allows air from jet engines to pass over the surface of the wing and fall on the flaps.
This creates a Coanda effect that increases the lift of the aircraft, allowing it to take off and land at lower speeds than aircraft with a conventional engine arrangement.
However, at the same time, the aircraft is inefficient from the point of view of high-speed movement, and its design requires special technical tricks to withstand the heat from the engine nozzles.
In fact, the AN-72 is of great importance for the history of transport aviation. In the 1970s, the USA and the USSR actively developed transport aircraft for short take-off and landing, and the AN—72 is the only such machine that has been used in practice.
There was a period in the history of transport aviation when the development of models capable of operating in poor conditions became a popular direction. The US Air Force, for example, ordered the development of C-14 and C-15 research aircraft from Boeing and Douglas, respectively, and both models made their first flights in the 1970s.
Nevertheless, these aircraft were not mass-produced due to the high cost of development, as well as due to various other costs.
The National Aerospace Laboratory of Japan (NAL) also ordered from Kawasaki Heavy Industries an experimental model of a shortened take-off and landing "Asuka" to improve the take-off and landing characteristics of the C-1 aircraft, which made its first flight in 1970. However, it also did not reach mass production.
Only the AN-72 remained. One of the reasons why it became one of the few aircraft with a shortened take-off and landing was that Soviet airfields were often equipped with equipment that did not allow for long take-offs. By the way, despite the fact that the AN-72 is similar to the Asuka in terms of the location of the engines and other characteristics, work on its creation began about ten years earlier.
Similar in design relatives of the AN-72
There are derivatives of the AN-72. These include the AN-74, equipped for use in the Arctic, and the AN-71 with an early warning radar installed in the tail section.
By the way, during the Cold War, NATO gave Soviet aircraft code names, in particular, the AN-72 is a Coaler, that is, a "Coal miner". In Russia, he received the nickname "Cheburashka" in honor of the character of Soviet cartoons, distinguished by large ears. Indeed, the AN-72 looks like a Cheburashka from the front: its engines look like big ears.
According to the official Twitter account of the Antonov company, the AN-225 Mriya is not the only aircraft destroyed during a military special operation in Ukraine. The list also includes the AN-74, a descendant of the AN-72.
As I noted above, so far the most successful project of a shortened take-off and landing aircraft is the AN-72, but will a similar concept appear in the future? I will follow the situation with interest.
Author: Masao Taneyama (Masao Taneyama)
Comments from Japanese readers
Tobanai taru
It's great that you wrote only about the benefits. However, due to the peculiarities of the upper wing surface blowing system, the airflow partially blocks the nozzle, which greatly reduces efficiency. This is a significant disadvantage in terms of ecology, fuel consumption and speed characteristics.
In addition, the flight characteristics differ from conventional aircraft, which also complicates maneuvering and control.
Per
When the engine is mounted directly on the wing, the highly heated jet exhaust blows over its upper surface, so the part must be made of high-temperature stainless steel or titanium, which inevitably increases the weight. In addition, it is necessary to develop a cooling system so that heat is not transferred to the wing beams. An increase in costs is inevitable.
Yas
When Michael Schumacher was driving for Ferrari, there was a case when the heat from the exhaust pipe heated the rear suspension, as a result of which the metal parts melted and failed. Solving thermal problems is not an easy task.
Nevertheless, I think that there will probably be a certain demand, for example, on islands or at airfields where maintenance of runways is difficult.
Err
I saw the AN-72 at the exhibition and its flights. The engine on the wing looks beautiful.
The possibility of a short takeoff and landing is also impressive. This is the only "working" aircraft of this type. By the way, the Coanda effect in some circumstances can make it difficult to take off and land.
Ntakkie
I think that the main reason why the AN-72 has become the world's only production aircraft is the low level of foreign objects entering the engines during takeoff and landing on rough terrain. This is important in Siberia and other remote regions.
Kix
Asuka demonstrated excellent performance during short takeoffs and landings. However, its performance characteristics differed significantly from other aircraft: it was too noisy and expensive. It was recognized that it was much more reasonable to lengthen the runway and use a conventional aircraft.
Tat
The HondaJet engines are not attached to the wings, but are located further away. Therefore, the wings are not affected by heat and have a large lifting force, which is very good. Speed and economy are important, but the ability to take off and land at a short distance is also important — this is an eternal problem.
Bf1
The USSR, which at that time copied everything that the West produced, copied this aircraft from the US Air Force transport YC-14. In the end, it remained at the development stage in the United States, and mass production was launched in the Communist bloc.
The Working Dead
The most famous aircraft with engines mounted above the wings is the A-10 Thunderbolt II. The essence of the design is that the wings shield the engines from ground fire. Another aircraft with engines mounted above the wings is the B-2.
Gt6
A long time ago, Asuka flew to an event at Okayama Airport. A large number of spectators gathered. But the engine didn't start, and the show had to be canceled. A very unpleasant memory.
