Intake momentum drag is an

aerodynamic Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an ...

phenomenon which affects

turboprop A turboprop is a Gas turbine, gas turbine engine that drives an aircraft Propeller (aeronautics), propeller. A turboprop consists of an intake, reduction drive, reduction gearbox, gas compressor, compressor, combustor, turbine, and a propellin ...

and jet-powered aircraft.Definition of Intake Momentum Drag?
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Causes

Intake momentum drag is caused by the consequence of the speed of the air entering the engine increasing, but where the exit speed of the air from the engine remains constant. The outcome therefore is that the amount by which the engine increases air velocity, ostensibly by way of the compression process, is reduced. A repercussion of this causes a slight reduction in the

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

of a jet engine.

Intake momentum drag yaw

Intake momentum drag yaw is a further consequence of intake momentum drag which affects

V/STOL A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to takeoff and landing, take-off or land vertically or on short runways. VTOL, Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do ...

(vertical and/or short take-off and landing) aircraft such as the

Hawker Siddeley Harrier The Hawker Siddeley Harrier is a British jet-powered attack aircraft designed and produced by the British aerospace company Hawker Siddeley. It was the first operational ground attack and reconnaissance aircraft with vertical/short takeo ...

. Intake momentum drag yaw is an aspect in which the mass of air ingested by the intake of the engine, whilst the aircraft is in the hover during a crosswind, can result in a state of uncontrolled roll (a secondary aerodynamic effect of yaw). The phenomenon was identified during the test flying programme for the Harrier and which required precise investigation. This resulted in test pilot John Farley deliberately flying right into the edge of this condition repeatedly, so that a system to counteract the effect could be developed.

References

Aerospace engineering Aerodynamics Classical mechanics Force {{Improve categories, date=March 2023