Vx and Vy

Question 1

Vx

Brenner

Answer 1

Vx, is the speed at which the aircraft has the largest amount of excess thrust, which means the greatest value of thrust minus drag.

As an aircraft climbs its indicated Vx does not change because total drag will be found at increasingly higher true air speeds.

Question 2

Vy

Brenner

Answer 2

Vy, the best rate of climb, is the speed at which the airplane has the greatest excess of power, meaning the greatest difference between the available power curve and the power required to maintain the flight.

As an aircraft climbs its indicated Vy decreases by 2% for every 1000 feet. Despite true Vy increasing by 1% for every 1000 feet.

Question 3

Absolute ceiling

Answer 3

Vx = Vy