032 - Performances
General
- VMCA = Velocity Minimal Control in the Air = minimal CAS at which the pilot can hold straight flight with no more
than 5° bank angle
Class A : 1,13VSR
- V2=1,1 VMCA ou 1,13VSR
More restrictive : low mass, large flaps extension, low elevation
- V R ≥ V 1 ou 105 % VMCA
- Net flight path gradient ≤ actual climb gradient
- Inoperative anti-skid decrease V1
- Decrease of temperature = increase of climb gradient
- Wind affects ground distance
- Mass affects time
- Density altitude is the pressure altitude corrected for “non standard” temperature
- Altitude ↗ Vx and Vy ↘ (↗ if expressed in TAS)
TAS
- Specific range= (Nm/gal)
Fuel Flow
- HWC=angle of flight path during climb
- More flaps = lower V1, VR, V2, Vx and Vy
- Rate of Climb (ROC) speed ↗ with mass ↗
- Low flaps = “distant obstacles”
- TOD=runway distance + distance of clearway which corresponds to ½ of runway distance
- Reduced screen height in case of wet runway
- Max banking between 50 and 400 ft : 15°
- Coefficient of lift is independent of altitude
1
- Induced drag is created by lift (= )
√ speed
- Turbo propeller : MLDA = 0,7 LDA
- A higher pressure altitude at ISA temperature decreases the field length limited T/O mass
- Service ceiling = VS => 100 ft/min
- Absolute ceiling = VS => 0 ft/min
- Maximum lift/drag ratio:
Maximum range for propeller
Maximum endurance for jet
Thrust−Drag
- Climb Gradient= .100
Weight
- V MCG <V 1 <V R <V LOF < V 2
- ROC increased when speed increased
- Wet runway = reduction of screen height is allowed in order to reduce weight penalties
- The climb limited T/O mass is independent of the wind component (it is a CS25 certification)
- Mass ↘ in a horizontal unaccelerated flight => minimum drag + IAS for minimum drag decrease
- Rate of climb = TAS * still-air distance
- Configuration and angle of attack have an effect on the angle of descent in a glide
- If the T/O mass of an aeroplane is tyre speed limited, downhill slope would have no effect on the maximum
mass for T/O
- A lower airspeed at constant mass and altitude requires a higher coefficient of lift
- The maximum speed in horizontal flight occurs when the maximum thrust is equal to the total drag
- Uphill slope increases the T/O distance more than the accelerate stop distance
- With all engines out, to fly the maximum time = the minimum power required
- ROC=still air gradient (slope) x TAS
- ROC speed increases with increasing mass
- Net flight path : 90m + 0,125D
- The best rate of climb at a constant gross mass decreases with increasing altitude since the thrust available
decreases
- Tailwind has no effect on maximum endurance speed
- The maximum mass for landing could be limited by the climb requirements… in the approach configuration
- Increased mass on the performance of a gliding aeroplane = speed for best angle of descent increases
- T + W sin GAMMA = D
- Induced drag decreases with speed increases
TAS Height drift ROC 6000
- AD=GD = Climb gradient = x
GS Gradient TAS 6080
Performance – Class B single engine
- Reciprocating engine => constant angle of attack, mass and configuration
With increasing altitude the drag remains unchanged but TAS increases
The power required increases and the TAS increases by the same percentage
- Maximum IAS in level flight is reached at the lowest possible altitude
- Increasing TAS decreases the angle of attack of the propeller
- Endurance depends on altitude, speed, mass and fuel on board
- Maximum endurance for a piston engine aeroplane is achieved at the maximum rate of climb speed
Performance – Class B multi engine
- Clockwise propeller rotation, critical engine = left engine
- distance x gradient ( % )+ 15 m−height=obstacle clearance margin
- The critical engine inoperative increases the power required and the total drag
- Landing short grass runway : x1,15
- Q410 → 150 ft
Performance – Class A – CS25
- 1st segment : “reference zero” → gear up
- 2nd segment : 400 ft : landing gear retracted → flap retraction
- 3rd segment : flap → beginning of the enroute climb (level burst at 400ft, flaps retracted, power to MCT)
Performance – Class A – CS25 - Certification
- ETOPS : 180 minutes from a suitable airport, in still air, with one engine inoperative
- ETOPS twin engine = 60 min on engine inop
- TODx1,15 for certification
- One engine inop : min 2000 ft
- Obstacle limited T/O mass should be determined on the basis of a 35 ft obstacle clearance
- Flex T/O are not allowed when anti skid inop or runway contaminated
- Max Tyre speed = GS
- Balanced field length gives the minimum required field length in the event of an engine failure
- Jet : 0,66 LDA (60%)
- Propeller = 0,7 LDA
VMO(CAS )
- Maximum operating limit speed=
MMO(M .)
- T/O net flight path : failure of the critical engine at Vef
- Vref=1,23 VSR0 down to 50 ft height
- Equivalent gross mass = gross mass corrected from T°
- Engine failure T/O run = horizontal distance… 35 ft
- 10% for ± 2% runway slope (only for uphill)
- 15% for a dry runway
- Distance AFM : 1,15 TODA 1,25 TORA 1,3 ASDA
Performance – Class A – CS25 - Meca
- Max Range = max still air distance = max NM/ Gal used
- Max endurance = the longest in the air
- Propeller : maximum endurance speed = minimum drag speed
- Long range cruise speed = 1,04 maximum range speed = 0,99 best endurance
- Holding speed = VMD (minimum drag = minimum fuel consumption)
- Maximum climb angle = max CL/CD (= VMD for jet)
- Drift down = obstacle clearance after engine failure
- Buffet Onset Boundary = Aerodynamics
Thrust−Drag
- sin ( Angle of climb ) =
Weight
- Constant IAS and increasing altitude : climb angle and pitch angle ↘
- TAS increases = pitch angle decreases
- The thrust of a jet engine at constant RPM increases in proportion to the airspeed
- VMO = lower altitudes – structural loads and flutter
- MMO = higher altitudes – compressibility and flutter
- Below the optimum cruise altitude : M. decreases
- Optimum altitude increases as mass decreases
- Balanced T/0
No CWY no SWY : V1=V1 balanced
CWY but no SWY : V1<V1 balanced (to reach MTOM)
SWY but no CWY : V1>V1 balanced (to utilize max ASDA)
