Cruise speed 75% at 8,000 ft is what?

Cruise speed 75% at 8,000 ft is what?

• A. 103 knots
• B. 110 knots
• C. 107 knots
• D. 105 knots

Answer: (C)

At a fixed percentage of power, the aircraft settles at a cruise speed where thrust available equals drag. Raising altitude to 8,000 ft reduces air density, so the engine/propeller produce less thrust and the wing operates in thinner air, altering the drag curve. The published performance data for a typical light trainer at 8,000 ft and 75% power shows a cruise true airspeed of about 107 knots. That value reflects the balance of thrust and drag under those conditions, accounting for the thinner air increasing TAS relative to what you’d read on the airframe’s pressure-based scales. So 107 knots is the correct cruise speed for 75% power at 8,000 ft. The other nearby numbers don’t align with this specific altitude-power combination and would correspond to different settings or altitudes.

At a fixed percentage of power, the aircraft settles at a cruise speed where thrust available equals drag. Raising altitude to 8,000 ft reduces air density, so the engine/propeller produce less thrust and the wing operates in thinner air, altering the drag curve. The published performance data for a typical light trainer at 8,000 ft and 75% power shows a cruise true airspeed of about 107 knots. That value reflects the balance of thrust and drag under those conditions, accounting for the thinner air increasing TAS relative to what you’d read on the airframe’s pressure-based scales. So 107 knots is the correct cruise speed for 75% power at 8,000 ft. The other nearby numbers don’t align with this specific altitude-power combination and would correspond to different settings or altitudes.