Aero 220

Question 1

What are the four stages of aircraft design?

Answer 1

Conceptual design, preliminary design, detail design and test/evaluation.

Question 2

Conceptual design

Answer 2

Aircraft configuration design

Question 3

Preliminary design

Answer 3

Determining the MTOW, power/thrust, and wing reference area.

Question 4

Detail design

Answer 4

Split into two parts. Part 1 - design dominant components, e.g. wing, tail, fuselage, propulsion systems and landing gear. Part 2 - design servant components, e.g. structural design, cabin.

Question 5

Test/evaluation

Answer 5

Aerodynamic testing in wind tunnel using aircraft model, and aircraft flight dynamic testing using prototype. Propulsion testing using an aero-engine.

Question 6

Lateral stability

Answer 6

Stability in roll (rotation about the longitudinal axis).

Question 7

Longitudinal stability

Answer 7

Stability in pitch (rotation about the lateral axis).

Question 8

Four benefits of a swept wing

Answer 8

Improved aerodynamic features due to delayed compressibility effects, moves centre of gravity, improves lateral stability, and improves pilot’s view.

Question 9

Dihedral

Answer 9

Improves lateral stability by generating a restoring moment.

Question 10

Canard tail

Answer 10

Tail mounted infront of the wing, often generates part of the aircraft’s lift.

Question 11

Location of most landing gear

Answer 11

Aft of the centre of gravity, which provides better control in landing and takeoff.

Question 12

Design point

Answer 12

The point on a matching plot that yields the smallest engine in terms of power.

Question 13

Five things on a matching plot

Answer 13

Stall speed, maximum speed, maximum rate of climb, take-off run, and ceiling.

Question 14

Take-off run

Answer 14

The distance between the take-off starting point to the location of a standard obstacle that the aircraft must clear.

Question 15

Rate of climb

Answer 15

The ratio between excess power and aircraft weight.

Question 16

Wing twist

Answer 16

Intentional twist along the wingspan so that the tip and root have a different angle of attack.

Question 17

Two benefits of having wing twist

Answer 17

Prevent tip stall before root stall (so better roll stability), and to optimise span-wise lift distribution to achieve minimum drag.

Question 18

Directional stability

Answer 18

Stability in yaw (rotation about the vertical axis).

Question 19

Horizontal tail

Answer 19

Responsible for longitudinal trim, stability and control.

Question 20

Vertical tail

Answer 20

Responsible for directional trim, stability and control.

Question 21

Problem with a T-tail configuration

Answer 21

A second stable trim point exists at high angles of attack, meaning the control effectiveness is greatly reduced and the aircraft can be locked in a deep stall.

Question 22

Best aircraft centre of gravity location

Answer 22

Around the wing/fuselage aerodynamic centre, so a smaller balancing moment is required for trim conditions.

Question 23

Wi+1/Wi

Answer 23

e^(-RC/(0.866Vc(L/D)max))