Subsonic Aerodynamics Part 1

Question 1

In a glide, added weight will reduce?

Answer 1

The glide endurance

Question 2

A heavier aircraft will achieve maximum lift/drag ratio at a higher?

Answer 2

Airspeed

Question 3

during a glide, the distance flown compared to increased weight, remains?

Answer 3

Unchanged

Question 4

How to calculate the load factor in a turn with a bank angle of 30?

Answer 4

load factor = n(1) / cos 30

Question 5

Centripetal force(or horizontal component of lift) in newtons, can be calculated using the formula:

Answer 5

Centripetal force = M v² / r

Question 6

To calculate the acceleration toward the centre, the following formula applies:

Answer 6

v² / r

v² = Velocity squared in m/s or ft/s

r = the radius in feet or metres

Question 7

As the aircraft bank angle increases, the vertical component of lift -

Answer 7

Reduces

Question 8

To prevent the aircraft from descending during a turn, either the _____ or the ____ of ____ must be ________ to maintain a greater ___ ___.

However, an ________ in _____ of _____ results in an ________ drag, which must be balanced by an increase in ____ if the _____ is to remain ______.

Answer 8

To prevent the aircraft from descending during a turn, either the speed or the angle of attack must be increased to maintain a greater total lift.

However, an increased angle of attack results in an increased drag, which must be balanced by an increase in power if the speed is to remain constant.

Question 9

Wing loading is the -

Answer 9

weight of the aeroplane divided by the wing area

Question 10

The ratio that exists between the lift produced by the wings and the weight of the aeroplane is referred to as load factor, and can be expressed as:

Answer 10

Load factor = L / W

Question 11

In level flight the load factor =

Answer 11

L / W = 1

Since lift is equal to weight, the load factor will be 1.

Question 12

At 30 degrees the load factor =

Answer 12

1.15

1 / cos 30 = load factor

Question 13

At 60 degrees the load factor =

Answer 13

2

1 / cos 60 = load factor

Compared to level flight, the wings must produce a value of lift which is equal to twice the weight of the aeroplane.

Question 14

Centripetal force(or horizontal component of lift) in pounds, can be calculated using the formula:

Answer 14

Centripetal force in pounds = W v² / g r

g = gravitational force in feet, 32 ft/s per second

Question 15

The greater the centripetal force, the -

Answer 15

less the turn radius becomes

Question 16

How to calculate the total lift(TL) given:

F(centripetal force) = 20 400

L(lift, which equals the weight of the aircraft) = 11 500

Answer 16

TL² = F² + L²

= 23 418Ibs

Question 17

Any manoeuvre which requires additional lift subsequently increases the load factor and thus raises the stalling speed. This true of any turn and the stalling speed may be calculated from the formula:

Answer 17

New stalling speed = Old stalling speed x √n(load factor)

Question 18

The maximum turn rate =

Answer 18

Velocity(ft.sec) / radius(ft) = time

Question 19

To summerise minimum radius turn:

Answer 19

1. Fly at any speed provided engine power can maintain it
2. Fly at the maximum permissible load factor(Cʟ max)
3. Air must be as dense as possible

Question 20

To summerise minimum rate turns:

Answer 20

1. Fly at the stalling speed(will provide the minimum speed, thus minimum radius)
2. Fly at maximum load factor(maximum total lift)
3. Air must be as dense as possible

Question 21

The value of the induced drag of an aeroplane in straight and level flight at constant weight varies linearly with:

Answer 21

1/V²