Engine Placement on Aircraft
Aircraft engines are large, complex components that cannot simply be stored under a hood or stowed away in the fuselage. The engine must be fitted to the aircraft in a specific way to meet two parameters: first, to ensure the engine will not come loose in any way, and second, to isolate the engine from the passengers and crew onboard. The answer to these two requirements is to either mount the engine under the wings, or near the rear of the aircraft. Each design has its advantages and disadvantages depending on the type of aircraft.
Commercial aircraft usually have an engine that is located under the aircraft wings. Since they are heavy, high functioning components, engines are fitted to the airframe or fuselage using different engine mounts. The weight of the engine needs to be distributed evenly and the vibration and torque emitted from the engine should be dissipated and absorbed by the mount. Most mounts are made out of a durable and lightweight material such as steel alloy tubing that is welded together. The two key types of mounts are the conical mount and the dynafocal mount. The conical mount is the easiest to construct and features 4 key mounting points. A downside of this mount is that it does not dampen vibrations or engine torque as much as the dynafocal mount. Generally, the dynafocal mount is viewed to be the better mount as they are consistent at reducing vibration, engine noise, and torque. Typically, a dynafocal mount is the less cost-efficient option.
Compared to engine situated at the rear of the aircraft, under wing engines are easier to access and maintain. They do not require as much structural work and they are safer in the event of fire. Pylons connect the engine mount to the wing of the aircraft. An advantage of a pylon connection is that the engine can be removed without the need to take the whole wing off. Pylons allow for different engines to be fitted to the aircraft. Although the engine mount is still in place, pylons should also be manufactured to withstand high levels of stress and vibration emitted from the engine.
Aircraft Pylons also help to ease the structural requirements of mounting an engine. Another advantage of having the engine located under the wing is that the engine is easier to access and maintain. From a safety point of view, the location is better as the engine is the furthest away from the passengers on board. A downside of this engine placement is that the engine is more susceptible to debris. The noise level is also higher.
In comparison, the rear mounted engine is usually found on smaller aircraft. The engine noise is quieter from inside the cabin and debris is not as likely to fall into the engine. The downside of this engine mounting is that it is harder to access and requires a more complex structural fitting than the pylon used in the wing engine mount.
In either case, the engine on an aircraft is an integral part of the aircraft that requires its own particular style of mounting. If the engine is mounted at an awkward angle or in the wrong location, the aircraft’s center of gravity will be thrown off. Whether it wing or rear mounted, dynafocal or conical mounted, with or without pylons, the engine placement needs to be exact.
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