What ground roll is needed for takeoff over a 50-foot obstacle at 80 degrees F and 15 kts headwind for a weight of 3,300 lb at a pressure altitude of 5,000 ft?

To determine the correct ground roll needed for takeoff over a 50-foot obstacle under the specified conditions, several factors must be considered, including aircraft weight, temperature, elevation, and wind conditions.

At a pressure altitude of 5,000 feet, the air density is lower than at sea level due to both the altitude and the temperature effect. Higher temperatures can also reduce engine performance, further affecting the aircraft's takeoff distance. The significant headwind of 15 knots provides a beneficial effect by reducing the groundspeed required for takeoff.

To calculate the required ground roll accurately, reference charts or performance data specific to the aircraft type will be utilized, considering the specific conditions stated. The 50-foot obstacle height influences the required runway length, meaning the performance figures must be adjusted to ensure safe clearance of that height during the takeoff climb.

Given those factors and the model's performance data, a ground roll of 1,950 feet aligns appropriately, factoring in the altitude, temperature, weight, and headwind benefits.

Thus, the selection of 1,950 feet as the ground roll needed to clear the 50-foot obstacle at the stated conditions properly reflects the necessary calculations and aerodynamic principles involved in determining takeoff performance in aviation.