Lecture 9

Question 1

List characteristics of a high wing aircraft*

Answer 1

Better lift/drag ratio
Better lateral (roll) stability
Shorter landing distance

Question 2

List characteristics of a low wing aircraft*

Answer 2

Easier to build strong landing gear support
Better roll maneuverability (less lateral stability)
Shorter take off distance

Question 3

What type of aircraft are more susceptible to ground effect?*

Why?

Answer 3

Low wing aircraft

Wingtip vortexes impact the ground and cause less induced drag

Question 4

List pro(s) and con(s) of a tee-tail horizontal stabilizer*

Answer 4

Pros:
Allows airflow over the rudder at a high AOA
Keeps horizontal stabilizer and rudder out of the main wing downwash
Keeps horizontal stabilizer out of the way of the engines

Con:
Vertical stabilizer must be larger and heavier

Question 5

What types of drag are reduced by using a v-tail horizontal stabilizer? How?

Answer 5

Interference drag: eliminating the number of acute angles
Pressure drag and skin friction drag: eliminating one of the horizontal flight controls

Question 6

List pro(s) and con(s) of a v-tail horizontal stabilizer*

Answer 6

Pros:
Lighter
Less wetted surface area
Reduced drag
Increased stealth (reduces radar reflection and infrared signature)
Improves safety and reduces cabin noise

Con:
Vertical stabilizer must be larger and heavier
Require a complex control system
Structurally more robust due to increased load
The amount of control surfaces required for operating the ruddervators are higher

Question 7

The horizontal surface on a v-tail aircraft is called a _____.

Answer 7

ruddervator

Question 8

On a v-tail aircraft, how do you yaw the nose left?*

Answer 8

Move the pedals left which deflects the left-hand ruddervator down and left and the right-hand ruddervator up and left

Question 9

On a v-tail aircraft, how do you pitch the nose up?

Answer 9

Move the control stick back which deflects the left-hand ruddervator up and right and the right-hand ruddervator up and left

Question 10

What is the purpose of having an H or split vertical stabilizer?

How would this help fighter aircraft?*

Answer 10

Fuselage tends to block the airflow to a normal single vertical stabilizer and rudder

To help stabilize in the event of damage and reduce the height needed for full control

Question 11

What aircraft had a triple vertical stabilizer?

Answer 11

Lockheed Constellation

Question 12

What do flying wires do?*

Where are they located?*

Answer 12

Transmit the lift back to the fuselage

Wire stretching from top wing to the bottom of the fuselage

Question 13

What do landing wires do?*

Where are they located?*

Answer 13

Transmit the downward impact of landing on the wings back to the fuselage

Wire stretching from bottom wing to top wing

Question 14

What do interplane struts do?*

Where are they located?*

Answer 14

Transmit the lift loads and landing loads between the top and bottom wings
Makes a biplane sturdier than a monoplane

Bars between the top and bottom wing located towards the wing tips

Question 15

What do cabane struts do?*

Where are they located?*

Answer 15

Support the top section of wing above the fuselage and transmit the lift loads of the wing roots to the fuselage

Bars from the top wing to the fuselage

Question 16

What is the center section?*

Where is it located?*

Answer 16

An airfoil shaped section above the fuselage to which the upper wings attach
Usually one of the only parts of the plane made of aluminum

Located where the two pieces of the top wing come together

Question 17

What are biplane wings usually made out of?

Answer 17

Wood ribs and fabrics skin to make it as light as possible

Question 18

What causes interplane interference?*

Answer 18

The gap between airfoils on a biplane are closer than a chord length apart
The high pressure from the bottom of the top wing to mix with the low pressure from the top of the bottom wing

Question 19

What is the “gap” when talking about biplanes?

Answer 19

The distance between the chord of the top wing and the chord of the bottom wing

Question 20

What is decalage?*

What does it affect?*

What is it at normally?*

Answer 20

When one of the wings is set to a higher angle of incidence than the other wing
On a fixed-wing aircraft: the angle of difference between the upper and lower wings of a biplane

Interplane interference

Typically zero with both wings having equal incidence

Question 21

What is the NASA AD-1?

Answer 21

An oblique wing aircraft
Wings could be pivoted obliquely from zero to 60 degrees during flight

Question 22

Who designed the NASA AD-1?

Who proposed the first oblique wing design?

Answer 22

Designed by Burt Rutan

Richard Vogt proposed the Blohm & Voss P.202 in 1942

Question 23

How does a tandem wing aircraft create lift?

How does this design achieve pitch stability?

Answer 23

Two wings, both wings lift up and there is no horizontal stabilizer pulling down

The front and rear wings at different angles

Question 24

List pro(s) and con(s) of a tandem wing aircraft*

Answer 24

Pro:
No horizontal stabilizer pulling down

Cons:
Pitch stability is very difficult to control
Very limited center of gravity range

Question 25

What is a canard wing aircraft?

How does this design create lift?

Answer 25

Special type of tandem wing

Both wings lift, but the Canard (small front wing) should carry no more than 25% of the total weight

Question 26

List pro(s) and con(s) of a canard wing aircraft*

Answer 26

Pro:
More lift efficient because both wings provide lift

Con:
No tail pulling down so not as stable in pitch as conventional aircraft

Question 27

What type of aircraft did the Wright Brothers make?*

Answer 27

Biplane canard aircraft

Question 28

How do you fix stability in pitch on a canard wing aircraft?*

Answer 28

Swept back wings
Making the canard wing stall before the main wing
Canard wing stops making lift before the main wing, and the aircraft does not pitch up too far

Question 29

Most airplanes we do not have to worry about _____ movements left and right.*

Answer 29

Center of Gravity

Question 30

List pro(s) and con(s) of a flying wing*

Answer 30

Pro:
Drag is reduced

Con:
Stability is difficult

Question 31

What are the flight controls for the flying wing? *

Where is each located?

Answer 31

Split rudders: at the wingtips
Elevons: move the ailerons towards the center and combine them with the elevators