How are VX and VY affected by altitude?

How are VX and VY affected by altitude?

Vy is slightly faster, and is the Maximum RATE of climb. It allows one to climb to altitude in the shortest time. They are shown here: With increasing altitude, Vx increases slightly while Vy decreases, until they are the same at the absolute ceiling, where the airplane cannot go higher.

How is VX and VY determined?

Vy – It’s All About Power Vx is all about excess force (thrust) – but Vy is all about excess power (horsepower). So, you can compute power required by multiplying your total drag (force required) by your airspeed (distance over time). Power Required = Thrust Required X Airspeed.

How does VY TAS change with altitude?

If Vy is measured as a true airspeed, it increases approximately 1% for every thousand feet increase in altitude. That’s right! If you measure Vy in terms of TAS it will increase, not decrease with altitude. Therefore, if Vy is 82 knots (TAS) at sea level, it must be approximately 90 knots (TAS) at 10,000 feet.

What is the best climb angle?

Best angle of climb, also known as Vx, is the true airspeed that allows an aircraft to gain the most amount of altitude in the shortest distance across the ground. The best angle of climb speed occurs when the difference between thrust available and thrust required is greatest.

What is the VY speed?

Best Rate of Climb
VX is known as the ‘Best Angle of Climb’. This is the speed that gives you the most altitude in the shortest distance. VY is known as ‘Best Rate of Climb’. Gives you the most altitude in the shortest time.

What does altitude have to do with VX and Vy?

You increase your angle of attack. At higher altitudes, because of the less dense air, you need to fly at a higher angle of attack for a given true airspeed. And, if you’re flying at a higher angle of attack, you’re generating more induced drag. So, as you climb, your angle of attack for level flight increases and you generate more induced drag.

How is the thrust of an aircraft related to speed?

To simplify things, we can say that thrust changes over speed in proportion to the expression $v^{n_v}$where $n_v$is a constant which depends on engine type. Piston aircraft have constant power output, and thrust is inverse with speed over the speed range of acceptable propeller efficiencies, hence $n_v$becomes -1 for piston aircraft.

What happens to the VY curve as you climb?

As you climb, the power required curve shifts up, moves to the right, and tilts. The power available curve drops straight down. Check it out: And, if you plot Vy as you climb, you’ll see that it moves slightly to the right.

How does altitude have to do with airspeed?

At higher altitudes, because of the less dense air, you need to fly at a higher angle of attack for a given true airspeed. And, if you’re flying at a higher angle of attack, you’re generating more induced drag. So, as you climb, your angle of attack for level flight increases and you generate more induced drag.