Why Tail-Mounted Engines Disappeared from Civil Aviation and Will Never Return

In the 1960s–1980s, the tail engine configuration was considered standard for many passenger aircraft. Aircraft such as the Tu-154, DC-9, Yak-42, and even early Boeing 727 models actively used this scheme — and did so quite reasonably. However, by the beginning of the 21st century, this architecture had almost disappeared from civil aviation. Why did this happen?

Design Complexities and Center of Gravity

One of the key reasons for abandoning the tail configuration was design limitations. Placing engines in the tail section of the fuselage requires significant reinforcement of the entire rear section of the aircraft. This not only increases the weight of the structure but also shifts the center of gravity backward, which complicates the balancing of the aircraft at all stages of flight — from takeoff to landing.

Moreover, this configuration almost inevitably leads to the use of a T-tail. Although it allows the engines to be placed higher above the ground and improves the cleanliness of the airflow, it creates serious risks during stalling. In critical modes, the airflow ceases to effectively wash over the elevators, which can lead to loss of control — a factor that modern safety standards consider unacceptable.

Operating Costs

From an operational point of view, the tail engine placement also proved to be less advantageous. Access to the engines for maintenance is difficult, especially at large airfields where ground equipment is geared towards working with underwing engines. Laying fuel lines through the entire fuselage increases the weight and complexity of the system, and in the event of a fire, the engine is closer to the passenger cabin, which increases safety risks.

However, the decisive factor was the physical growth in engine size. Modern high-efficiency turbofans have a huge fan diameter — sometimes more than three meters. Placing such units in the tail section of the fuselage became technically impossible without radically redesigning the entire structure. Under the wing, there is not only space for them, but also an aerodynamic advantage: the wing partially dampens noise, and the engines are better cooled by the oncoming flow.

Not a Mistake, but Evolution

The tail configuration was never a mistake — it simply ceased to meet new realities. The increasing demands for fuel efficiency, safety, maintenance costs, and environmental friendliness have made underwing engine placement the optimal solution for most modern passenger aircraft. Exceptions remain only in niche segments — for example, in some regional business jets, where compactness and short takeoff are more important than other factors.

Thus, the departure of tail engines from civil aviation is not a failure of engineering thought, but a logical stage of technological evolution.