Aerodynamic Theory Review 1ATC Chapter 6

Aim

To review climbing and descending

Objectives1.State the forces in a climb2.Define rate and angle of climb3.State the forces in a descent4.Define rate and angle of descent

R.A.F

W

DT

L

What are the four forces acting on our aircraft in straight and level?

1. Forces in a climb

R.A.F

W

DT

L

PCW

RCW

RCW

We can see weight is acting at an angle to all the other forces so we can break it up into a Perpendicular Component of Weight and a Reward component of weight

1. Forces in a climb

R.A.F

W

DT

L

PCW

RCW

RCW

We can now resolve the force vectorsIs the aircraft in equilibrium?

R2

R1

1. Forces in a climb

R.A.F

W

DT

L

PCW

RCW

RCW

We must increase the power to overcome the RCW

R2

R1 R1

T

The aircraft is now in equilibrium

1. Forces in a climb

R.A.F

W

D

L

PCW

RCW

RCW

R2

R1 R1

T

In Summary:

R1 = R2L < WT = RCW + D

The aircraft is in equilibrium

1. Forces in a climb

We can describe climb performance as either Rate of Climb or Angle of Climb

Rate of climb is the altitude gained over time. Expressed in feet per minute (fpm).

2. Rate and angle of climb

Altitude

Time

We can describe climb performance as either Rate of Climb or Angle of Climb

Rate of climb is the altitude gained over time. Expressed in feet per minute (fpm).

2. Rate and angle of climb

Altitude

Distance

Angle of Climb

Angle of climb is the altitude gained over distance. Expressed as an angle

Definition of Power

Work = Force x Distance

WorkTime

Power =

Force x Dist.TimePower =

2. Rate and angle of climb

Power is supplied by the engine and can be described as the amount of work that can be done in a given amount of time

Thrust is the force applied to the Airflow by the propellerAs we increase speed less thrust will be imparted on the airflow Thrust is limited by the Power Available

Definition of Thrust

2. Rate and angle of climb

Maximum altitude gain over a given time. Achieved by flying at best RoC speed also known as Vy.For the C172SP Vy is 74 KIAS at Sea LevelOur best Rate of Climb (VY) occurs at the point of Max Excess Power

2. Rate and angle of climbBest Rate of Climb

Pa-PrWRoC = 33000 x

Maximum altitude gain over a given distance. Achieved by flying at best AoC speed, Vx.For the C172SP Vx is 62 KIAS at Sea LevelBest Angle of Climb occurs at Max Excess Thrust

2. Rate and angle of climbBest Angle of Climb

Thrust - DragW

AoC = Sin x

Comparison of altitude and distance gained over the same time period at Vx and Vy.

2. Rate and angle of climb

R.A.FW

L

D

What are the forces acting on our aircraft in S&L?

3. Forces in a descent

R.A.FW

L

D

FCW

FCW

PCW

Again we can see weight is acting at an angle to our other forces so we can break it up

3. Forces in a descent

R.A.F

W

L

D

FCW

FCW

PCW

We can now resolve the forces

R

The aircraft is now in equilibrium

3. Forces in a descent

R.A.F

W

L

D

FCW

FCW

PCW

R

In Summary:L < WR = WD = FCW

3. Forces in a descent

The aircraft is now in equilibrium

Like a climb we can describe descent performance as either Rate of Descent or Angle of Descent

Rate of descent is the lost gained over time, expressed in feet per minute (fpm).

4. Rate and angle of climb

Altitude

Time

Like a climb we can describe descent performance as either Rate of Descent or Angle of Descent

Rate of descent is the lost gained over time, expressed in feet per minute (fpm).

4. Rate and angle of climb

Angle of climb is the altitude gained over distance. Expressed as an angle

Altitude

Distance

Angle of Descent

Questions?