If the unaccelerated stall speed is 60 knots, what is the stall speed under a load factor of 2.5 Gs?

If the unaccelerated stall speed is 60 knots, what is the stall speed under a load factor of 2.5 Gs?

• A. 84 knots
• B. 96 knots
• C. 120 knots
• D. 60 knots

Answer: (B)

Stall speed rises with the square root of the load factor because increasing weight (or G-load) requires more lift to reach the same coefficient of lift, so you have to fly faster to generate that lift. With an unaccelerated stall speed of 60 knots, and a load factor of 2.5 Gs, the stall speed is Vs = 60 × sqrt(2.5) ≈ 60 × 1.581 ≈ 95 knots, which is about 96 knots. So the best match is the option around 96 knots. The other speeds don’t fit the math: 60 knots is the unaccelerated value, and 84 or 120 knots would correspond to different load factors (roughly 2 Gs or about 4 Gs, respectively).

Stall speed rises with the square root of the load factor because increasing weight (or G-load) requires more lift to reach the same coefficient of lift, so you have to fly faster to generate that lift.

With an unaccelerated stall speed of 60 knots, and a load factor of 2.5 Gs, the stall speed is Vs = 60 × sqrt(2.5) ≈ 60 × 1.581 ≈ 95 knots, which is about 96 knots.

So the best match is the option around 96 knots. The other speeds don’t fit the math: 60 knots is the unaccelerated value, and 84 or 120 knots would correspond to different load factors (roughly 2 Gs or about 4 Gs, respectively).