Thrust, drag, lift and weight. These are the four forces which affect an aircraft at any one time during straight-and-level, unaccelerated flight. Depending on the value of these forces as they’re applied to an aircraft, different impacts will be felt by the Aircraft structure and its trajectory will change. Non-destructive testing in aerospace industries is needed because sometimes the forces which impact an aircraft are stronger than the forces holding the craft together. Regular non-destructive testing of aircraft components ensures aircraft structural integrity which is crucial to ongoing pilot safety and mission success.
What Forces Affect an Aircraft in flight?
As mentioned in the introduction, the four forces which affect an aircraft in flight are thrust, drag, lift and weight. These each affect different parts of an aircraft during straight-and-level unaccelerated flight. These forces are all co-dependent. Considering the speed at which commercial and government aircraft travel through the air, it’s inferred that the values of the forces affecting various parts of an aircraft are very large.
Thrust is provided by the engine and propellers and launches the aircraft on a forwards trajectory. Thrust is larger than drag. It is considered in most cases to have an effect over a longitudinal axis.
Drag is produced by disruption of the air by components which protrude off the aircraft. It retards the plane’s forward motion and can be considered to oppose thrust.
Lift is a force produced by the dynamic effect of the air acting on the aerofoil. It acts parallel to the flight path and perpendicular to the lateral axis. Lift opposes the downward force of weight
Weight is defined as the combined load of the aircraft itself, the crew, the fuel, and the cargo or baggage. It pulls downwards towards the surface of the Earth and manifests due to gravity.
Perhaps most important to consider is that these forces must act together with a sum of zero. If the net sum of forces is not 0 then the aircraft won’t continue in a straight-and-level trajectory. The pilot can adjust several components of the aircraft to counterbalance high value forces at different stages of the flight path and achieve either a level flight path, an upwards-inclining flight path (climbing) or a downwards-inclining flight path (descent). If a pilot manipulates aircraft components to a degree which produces a non-zero-sum net force too quickly, then aircraft components will sustain force which can damage protruding components.
Why is Non-Destructive Testing Needed in Aerospace?
Non-destructive testing is needed in aerospace industries when, as mentioned above, the motions of flying an aircraft produce a non-zero net sum of forces too quickly. When this occurs, damage to aircraft components can occur as forces which are larger than those holding the aircraft together impact the aircraft. NDT can be used on the ground to check for defects and damage to aircraft components and ensure they are in good enough condition to continue to fly.
Ultrasonic testing is the best way to achieve effective inspection of aircraft components. This is primarily due to the size of aircraft, however, the efficacy of ultrasonic non-destructive testing in general is reason enough to apply it in the evaluation of aircraft. Ultrasonic testing works by projecting a high-frequency sound wave through an object using a sender and receiver. The receiver will identify any structural irregularities or discontinuities in the test object which can then be repaired or removed.
Contact NDT Australia
If you are looking for non-destructive testing equipment, check out NDT Australia’s online store. We supply a range of NDT technology, including ultrasonic non-destructive testing equipment. We are open for business Monday to Friday, 7:30am to 4:00pm. Contact our friendly sales team on (02) 9524 0558 to ask any questions or to place an order for any of the products listed on our online store.