MASS AND BALANCE

Question 1

What’s the difference between Mass and Weight?

Answer 1

Mass is the amount of matter inside a body

Weight is the resultant force created by gravity (9,82 m/s)

Question 2

What happens to mass and weight in a turn?

Answer 2

Mass stays the same but weight increases (G-forces)

Question 3

Triangle to calculate mass and balance?

Answer 3

Mass x arm = Moment.

Moment on top and Mass and arm at the bottom

Question 4

Describe the T/D and L/W relationship?

Answer 4

Thrust acts lower than drag

Weight acts forward of lift

Question 5

What’s the purpose of the tailplane?

Answer 5

To balance out any residual moments that the L/D and L/W moments can’t fix

Question 6

Relationship of stability/controllability with fwd and aft CG positions?

Answer 6

Fwd CG: Greater stability, less controllability

Aft CG: Greater controllability, less stability

Question 7

What is the “Neutral point”?

Answer 7

Total controllability and neutral stability exits here. Happens when the aerodynamic centre is located where the CG is. A gust puts the nose up and the plane stays in that position. Not desireable so the CG is set fwd of the neutral point.

Question 8

What is static margin?

Answer 8

Distance between the Neutral point and the CG

Question 9

What will happen if the CG is aft of the neutral point?

Answer 9

The mass of the a/c acts with the downforce of the elevator to pitch the a/c up. This reduces controllability until it’s uncontrollable

Question 10

Which factors affect the longitudinal CG position?

Answer 10

1. Fuel burn
2. Flap position. CG moves rearwards with extension
3. Gear position. CG moves with gear movement
4. Cargo. Movement of payload may alter CG

Question 11

Which 3 CG points must be calculated on a W/B sheet?

Answer 11

1. ZFM
2. TOM
3. LM

Question 12

Describe what happens with Fwd CG in regards to:

1. Stability/controllability
2. Climb angle
3. Stall speed
4. Fuel burn
5. Final approach speed

Answer 12

1. Stability increases and controlability decreases
2. Climb angle decreases
3. Increases due to more downforce needed from the elevator.
4. Increase due to more trim drag and wing loading which requires more power to maintain a given airspeed
5. Final approach speed increases cause more power is needed to keep the plane from nosing in

Question 13

Describe what happens with Aft CG in regards to:

1. Stability/controlability
2. Climb angle
3. Stall speed
4. Fuel burn
5. Spin recovery
6. Glide distance

Answer 13

1. Stability decreases and controlabilty increases
2. Climb angle increases
3. Stall speed decreases
4. Fuel burn decreases due to less trim drag and wingloading
5. More difficult as a flat spin is probable
6. Gliding is more difficult

Question 14

Why is a W/B sheet cut off in the left top corner?

Answer 14

To not get too much stability

Question 15

Describe the weight schedule?

Answer 15

Aircraft Empty mass
\+Unusable fuel and oil
Basic Empty mass
\+Crew and catering
Operating Emtpy mass
\+Payload
Zero fuel mass
\+Fuel
Ramp mass
-Taxi fuel
Take-off mass
-Trip fuel
Landing mass

Question 16

Triangle to convert volume into weight?

Answer 16

Volume x SG = Weight

Weight on top and volume and SG at the bottom

Question 17

Load shifting formula?

Answer 17

m/M = d/D

m = mass to be moved
M = mass of the aircraft
d = distance CG will be moved from it's origin
D = distance the mass is moved

Question 18

How is MAC defined?

Answer 18

Half semi-span and measure the chord at this o

point

Question 19

Describe how MAC is calculated?

Answer 19

A-B/C x 100

A = Dist from the datum to CG
B = Dist from the datum to LeMAC
C = Length of MAC

Question 20

Standard mass for crew?

Answer 20

85 kg

Question 21

From what age is a person a child?

What is the std weight of a child?

Answer 21

From 2 years to 12

35 kg

Question 22

Definition of Aerodynamic Centre?

Answer 22

The point where total pitch down moments = total pitch up moments