Flight

Question 1

What are the three generally accepted definitions of the range of an aircraft

Answer 1

Safe range: max horizontal distance between two airports between which the aircraft can fly a safe, reliable regular service

Still air range SAR: horizontal distance covered, excluding the take off distance.

Gross still air range: theoretical max range of an aircraft without considering external factors. Take off and climb ignored

Question 2

What degrees climb angles can we use small angle approximation on

Answer 2

Less than approx 13 degrees. So cosø = 0 , L=W

Question 3

Why can the climbing flight,at steep angles, lift/drag ratio be the same as that for SLF

Answer 3

Because it’s climbing in non-accelerated flight.

Question 4

How to find service ceiling and absolute ceiling from an altitude vs R/C graph (also define what service ceiling and absolute ceiling are )

Answer 4

Absolute ceiling is the altitude at which the max. R/C = 0.
Service ceiling is the which the max R/C = 100ft/min = 30.48 m/min

Question 5

What is range and what is endurance

Answer 5

Range .. Total distance (measured with respect to the ground ) travelled by the aircraft in a tank of fuel

Endurance.. total time that an aircraft stays in air on a tank of fuel

Question 6

Three stages of take off ?

Answer 6

1. Acceleration at constant altitude
2. Rotation
3. Climb to clear 35ft

Question 7

What is a typical mission for a military aircraft

Answer 7

• climb
• cruise
• loiter
• enemy engagement
• descend to unload cargo
• climb 2
• return to cruise
• hold and descent

Question 8

What is SFC

Answer 8

Specific fuel Consumption… weight of a fuel consumed per unit power per unit time
SFC= c = lb of fuel / (ft.lb/s)(s) = N of fuel/ (J/s)(s)

Question 9

How to maximise endurance (propellor aircraft)

Answer 9

1. Highest propellor efficiency
2. Lowest specific fuel consumption, c
3. Highest fuel weight Wf=W0-W1
4. Fly at max Cl^3/2 / Cd value .. same setting as min power.
5. Fly at sea level as density largest value at sea level

Question 10

How to maximise range (propellor aircraft)

Answer 10

1. Highest propellor efficieny
2. Lowest SFC
3. Highest ratio of W0/W1 .. largest fuel weight
4. Fly at max Cl/Cd which is same setting for minimum thrust

Question 11

What is TSFC

Answer 11

Thrust specific fuel consumption, ct
Weight of fuel consumed per thrust per unit time
TSFC= N of fuel/ (N of thrust) (s)

Question 12

How to maximise range (jet propelled)

Answer 12

1. Min TSFC
   2.Max fuel weight Wf
2. Fly at setting for max Cl1/2/CD
3. Fly at high alts where density is smaller

Question 13

What is the take off performance of an aircraft quoted as

Answer 13

The distance required to reach an altitude of 35ft after starting from rest, on level ground, in still air, at sea level, in ISA conditions, at the max all-up-weight with all engines operative.

Question 14

What three segments make up the landing phase

Answer 14

1. The approach
2. The flare
3. The ground roll