What are the three generally accepted definitions of the range of an aircraft
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
What degrees climb angles can we use small angle approximation on
Less than approx 13 degrees. So cosø = 0 , L=W
Why can the climbing flight,at steep angles, lift/drag ratio be the same as that for SLF
Because it’s climbing in non-accelerated flight.
How to find service ceiling and absolute ceiling from an altitude vs R/C graph (also define what service ceiling and absolute ceiling are )
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
What is range and what is endurance
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
Three stages of take off ?
- Acceleration at constant altitude
- Rotation
- Climb to clear 35ft
What is a typical mission for a military aircraft
- climb
- cruise
- loiter
- enemy engagement
- descend to unload cargo
- climb 2
- return to cruise
- hold and descent
What is SFC
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)
How to maximise endurance (propellor aircraft)
- Highest propellor efficiency
- Lowest specific fuel consumption, c
- Highest fuel weight Wf=W0-W1
- Fly at max Cl^3/2 / Cd value .. same setting as min power.
- Fly at sea level as density largest value at sea level
How to maximise range (propellor aircraft)
- Highest propellor efficieny
- Lowest SFC
- Highest ratio of W0/W1 .. largest fuel weight
- Fly at max Cl/Cd which is same setting for minimum thrust
What is TSFC
Thrust specific fuel consumption, ct
Weight of fuel consumed per thrust per unit time
TSFC= N of fuel/ (N of thrust) (s)
How to maximise range (jet propelled)
- Min TSFC
2.Max fuel weight Wf - Fly at setting for max Cl1/2/CD
- Fly at high alts where density is smaller
What is the take off performance of an aircraft quoted as
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.
What three segments make up the landing phase
- The approach
- The flare
- The ground roll
