During a cruise flight of a jet aeroplane at constant flight level and at the maximum range speed, the IAS/the drag will?

In a cruise flight at a constant altitude and at maximum range speed, the indicated airspeed (IAS) will actually remain constant while the aircraft is operating under stable conditions. When flying at maximum range speed, the objective is to minimize drag to optimize fuel efficiency and extend the distance that can be traveled.

As the aircraft maintains this speed and altitude, the drag acting on it is primarily a function of the dynamic pressure and the shape of the aircraft, which is balanced by the thrust provided by the engines. At maximum range speed, the aircraft operates in a region of lift-to-drag ratio that is most favorable, creating a scenario where any change in speed would not increase performance. Therefore, during this phase, any variation from the ideal speed would lead to increased drag.

In this balanced flight situation, at maximum range speed, drag typically decreases as IAS decreases, particularly as the aircraft reaches the optimal configuration for minimal drag (like optimal angle of attack) where adjustments to the speed could lead to fuel efficiencies. However, since the conditions specify "constant flight level and maximum range speed," IAS remains steady.

This understanding leads to the conclusion that both IAS remains steady and the drag does not necessarily increase if parameters are kept constant, thus confirming the relationship as