Why Don't Commercial Airplanes Have Vertical Takeoff Engines?

When we talk about commercial airliners, we often discuss large twin-engine jetliners that operate on conventional runways. However, there are indeed aircraft capable of vertical takeoff and landing (VTOL), but why are such engines not found in commercial airliners?

VTOL Capabilities in Commercial Aircraft

There are commercial VTOL aircraft and VTOL-capable helicopters, such as the helicopters used in the oil and gas industry for ferrying crews to and from remote locations like oil platforms. These aircraft are typically used in charter operations rather than scheduled commercial flights.

Cost and Payload Considerations

The primary reason for the absence of VTOL capability in commercial airliners is cost and payload restrictions. The development and production of VTOL aircraft have historically been extremely costly, often sacrificing payload and range for vertical takeoff and landing (VTOL) versatility.

For example, the F-35B Lightning II has VTOL capability, but it has significantly less range and payload than its conventional takeoff F-35 variants. Similarly, the GA619 VTOL fixed-wing aircraft, developed by Augusta Helicopters, has seen little interest from the commercial market and has not received substantial development since 2015.

Operational Environment and Trade-offs

Commercial airliners operate in environments where they pick up and drop off cargo and passengers at limited facilities. These facilities are typically equipped with long, straight runways. Accelerating to flying speed and decelerating from flying speed is essential for these aircraft. VTOL capability is not required for this process, making it unnecessary.

Let's take the Boeing 767-300ER as an example. It has a maximum takeoff weight of 412,000 pounds and is powered by a pair of engines developing between 52,000 and 62,000 pounds of thrust each. Even with VTOL capability, the plane would need more than 412,000 pounds of thrust, which is more than double the thrust of the Boeing 767's engines. This would lead to a significant reduction in payload and range, making it economically unviable for commercial operations.

Efficiency and Fuel Consumption

In VTOL aircraft, the engine designs often have complex airflow paths, leading to efficiency losses. For instance, the Harrier's engine has a convoluted air path, generating pressure drops that reduce overall efficiency. Additionally, during VTOL operations, the plane operates below stall speed, meaning that without engine thrust, it would fall out of the sky.

Conversely, in a commercial aircraft, conventional takeoff and landing provide a stable and frictionless airspeed, allowing for correct and controlled landings. For example, during the infamous Miracle on the Hudson, if the plane had been making a vertical takeoff and one engine failed, the crew would have faced immediate and certain disaster due to the lack of airspeed and lift.

Conclusion

The absence of VTOL engines in commercial airliners is due to a combination of high development costs, payload limitations, and the operational efficiencies of conventional takeoff and landing. These factors make VTOL capability economically and practically unfeasible for commercial airlines, ensuring the continued dominance of large, efficient, and cost-effective airplanes in the commercial aviation industry.