Landing Gear & Flaps

Question 1

What are the two main configurations for landing gear?

Answer 1

Tricycle - Have a nose wheel (C-172). Most common

Conventional - Have a tail wheel (taildraggers)

*Both of these can be fixed or retractable

Question 2

What are the advantages of Tricycle Gear vs Conventional?

Answer 2

1) Doesnt ‘nose over’ as easily
2) Better directional stability and overall ground maneauvering
3) Visibility over the nose while taxiing
4) Landing is easier compared to taildraggers due to C of G position

Question 3

What are the advantages of Conventional (taildragger) planes?

Answer 3

1) Prop is higher off the ground
2) The third wheel is super small and creates less overall drag = better performance
3) Better for rough terrain/runways
4) Less damage to the plane if a wheel gives out.

Question 4

Why is landing a traildragger more challenging than a plane with conventional landing gear?

Answer 4

C of G is behind the main wheels. So if the AC starts to yaw to the left, the weight comes off the right wheel, the right wing lifts, the left drags, and that encourages the plane to keep turning faster and faster.

This is called a ‘ground loop’

Question 5

What are the benefits of retractable gear?

Answer 5

A huge reduction in parasite drag and noise

Question 6

What methods are used to retract/extend gear?

Answer 6

1) Electric motor( common, monstly on smaller AC)
2) Hydraulic pump (common, mostly on cummuters or bigger),
3) Manual (usually a backup option)

Question 7

What are some disadvantages of a plane with retractable gear?

Answer 7

1) More systems that can fail = more complicated and expensive maintenace

2) You could forget to put gear down/it could get stuck = higher insurance cost

3) Because the gear could get stuck up, you need to know more emergency procedures

Question 8

What are the three main types of main landing gear?

Answer 8

1) Split Axel- Bungee cord or Oleo
2) Spring Leaf/Steel or composite Cantilever - Steel flexes to absorb shock (C-172, DA-20)
3) Single Strut - Uses an Oleo system to absorb shock (Cherokee)

Question 9

What is a split Axel landing gear with bungee chord?

Answer 9

Split axel type has the axel (the ‘legs’ that attached the wheels to the plane) split in the middle and uses elastic shock bungee cords wound around a fuselage member.

This enables the whole assembly to spread when loads come through it.

A strut or tie rod is usually incorporated to brace the structure against side loads

Question 10

What is a Spring Leaf landing gear?

Answer 10

Literally just a steel tube stuck in the side of the plane. Shockingly very strong despite how they look. (Uses extensively on C-172 and some Diamonds)

Consists of a single strop of steel bent to form the shape of the undercarriage. It is attached to the fuselage in a cradle bulkhead by bolts.

It is capable of storing energy in initial impact, thereby producing very low load factors. Simple, long service life, and low maintenance

Question 11

What is a Single Strut Oleo style Landing Gear?

Answer 11

A system with air and hydraulic fluid. Common on Cherokees.

Question 12

What is differential breaking?

Answer 12

Allows you to use right and left breaks independantly. Helps with maneuvering on the ground.

Question 13

What type of breaks to most airplanes have?

Answer 13

Hydraulic disc breaks, similar to those found on cars. Except AC have differential breaking.

Question 14

How should braking be used when landing?

Answer 14

Always taxi and land in a way that requires the minimum amount of braking.

On short final, be aware of the position of your feet. Heels on the floor, toes on the ruddar pedals

Question 15

What two main things should you be looking for when checking breaks on your walk around?

Answer 15

Red liquid on the ground (indicates hydraulic leak in break line)
Wear on the break disk (can develop a groove where the break pads touch it when applying the breaks

Question 16

What is the main purpose of flaps?

Answer 16

Allow us to increase the lift (but also the drag) of a wing by increasing the camber of that wing.

In some specifically designed wings, flaps also allow us to increase the sureface area of the wing.

Question 17

How do flaps move?

Answer 17

Mechanically (Cherokee)
Electrically (Cessna 152/172)
Hydraulically

Question 18

What happens in most airplanes when you put flaps down and what should you do to conteract it?

Answer 18

AC will start to pitch up, pilot should trim down a tiny bit.

Question 19

Why do we put flaps down?

Answer 19

To get a steeper angle of descent and greater visibility. If you trim down to counter the increased angle of attack that flaps cause, your airspeed should stay the same.

Every time you lower the flaps more, you should pitch down and trim a tiny bit.

Question 20

What else do flaps allow us to do beyond a steeper angle of descent and better visibility?

Answer 20

They allow us to slow down (which increases our angle of descent even more)

Question 21

What types of flaps are there (5)?

Answer 21

Question 22

What is a flaperon?

Answer 22

A type of control surface that combines aspects of both flaps and airlerons.

In addition to controlling the roll/bank like normal ailerons, both flaperons can be lowered together to function like a dedicated set of flaps.

The pilot has seperate controls for ailerons and flaps and a mixer is used to combine the seperate inputs into this singel set of control surfaces called flaperons

Question 23

What are cowl flaps?

Answer 23

Found on high performance piston engine AC. Adjustable openings that help pilot control the amount of cooling air circulating around the engine.

Used during high power settings, such as during takeoff nd climb.