Moving weight from aft to forward cargo has what effect on cruise speed and stall speed?

Moving weight from aft to forward cargo has what effect on cruise speed and stall speed?

• A. Higher cruise speed and lower stall speed.
• B. No change in cruise speed and stall speed.
• C. Lower cruise speed and higher stall speed.
• D. Increases both cruise and stall speed.

Answer: (C)

Moving weight forward changes the aircraft’s longitudinal balance and trim requirements. Shifting cargo from the aft section to the forward section makes the CG more forward, which increases the tail’s downforce needed to keep the airplane level. That additional tail-down force adds drag during cruise, so for the same power or thrust, the aircraft’s cruise speed drops. Stall speed, on the other hand, is set by weight, wing area, air density, and the wing’s maximum lift coefficient. With total weight unchanged, V_s (the speed at which the wing can no longer provide enough lift) stays essentially the same, regardless of where the weight sits in the fuselage. So the expected effect is a lower cruise speed with stall speed remaining roughly constant. The idea that stall speed would rise isn’t supported by the basic relationship V_s ∝ sqrt(W/(S Cl_max)) when weight is unchanged.

Moving weight forward changes the aircraft’s longitudinal balance and trim requirements. Shifting cargo from the aft section to the forward section makes the CG more forward, which increases the tail’s downforce needed to keep the airplane level. That additional tail-down force adds drag during cruise, so for the same power or thrust, the aircraft’s cruise speed drops.

Stall speed, on the other hand, is set by weight, wing area, air density, and the wing’s maximum lift coefficient. With total weight unchanged, V_s (the speed at which the wing can no longer provide enough lift) stays essentially the same, regardless of where the weight sits in the fuselage.

So the expected effect is a lower cruise speed with stall speed remaining roughly constant. The idea that stall speed would rise isn’t supported by the basic relationship V_s ∝ sqrt(W/(S Cl_max)) when weight is unchanged.