SIFT Army Aviation Information Practice Test

What condition contributes to increased parasitic drag in helicopters?

1. High altitude flying

2. Increased speed

3. Excessive weight

4. Wind turbulence

The correct answer is: Increased speed

Increased speed leads to heightened parasitic drag in helicopters due to the way aerodynamic forces interact with the rotor system as the aircraft accelerates. Parasitic drag is a component of total drag that includes form drag, skin friction, and interference drag. As the helicopter moves faster, the airflow over its surfaces becomes more turbulent and the pressure differences that arise can increase drag due to skin friction and surface irregularities contributing more significantly at higher velocities. In the context of helicopters, this drag becomes more pronounced as the speed of flight rises, resulting in greater resistance to forward motion. This higher drag not only affects the efficiency of the helicopter's flight but also requires more power to maintain speed, which can influence operational parameters like fuel consumption and overall performance. While factors such as high altitude flying, excessive weight, and wind turbulence can influence a helicopter's performance in various ways, they do not specifically address the increase in parasitic drag associated with speed increases. At high altitudes, for example, air density decreases, which can actually reduce drag. Similarly, excess weight typically contributes more to induced drag rather than parasitic drag, and while wind turbulence can cause variations in drag, it does not systematically increase parasitic drag in the same consistent manner that increased speed does