Performance Flashcards
Automatic Thrust Control System
Senses engine failure through FADEC and reduces shaft HP on opposite outboard engine if airspeed below Minimum Power Restoration Speed (VMPR)
Reduces:
1) Rudder requirements
2) VMCA
3) VMCG
Minimum Power Restoration Speed (VMPR)
Airspeed at which engine is restored to full power (aka AS that allows ATCS to turn off)
Best Climb Speed
Higher of speed for MAX ROC or flaps UP air minimum control speed
Flaps Up Safety Speed (FUSS)
Min speed recommended for normal operation with flaps retracted.
FUSS is the higher of:
- 1.25x flaps up power off stall or
- flaps up air minimum control speed.
No less than 135
Normal Bleed (Takeoff)
Having pressurization, A/C packs, and underfloor heating on
All Bleed (Takeoff)
Having pressurization, A/C packs, and underfloor heating on,
PLUS
Engine, and wing and empennage ice protection on
Bleed Off (Takeoff)
Having A/C packs, Wing and Empennage off and underfloor switch in FAN
Recommended Takeoff
- Runway Availble Longer than Critical Field Length
- Refsual Speed (VREF) is higher than critical engine failure speed (VCEF)
- Because VREF is based on total runway available and VCEF is based on CFL
Minimum Recommended
Runway Available Equal to CFL
- RWY and CFL are equal and critical engine failure occuers, the distance to continue on three-engines equals distance to stop.
- VCEF and VREF are equal
Not Recommended
Runway Available Less Than CFL
- If an engine fails, it is not possible to stop or continue the takeoff within remaining runway
- Airplane must be downloaded for a safe takeoff (reduce weight)
Critical Field Length (CFL)
Runway distance required to accelerate on all engines, experience an engine failure, then continue takeoff or stop within same distance.
Used to determine maximum gross weight for a safe takeoff and climb out.
CFL must be no greater than the runway available.
Conditions to determine CFL
Weight
RWY Slope
RWY condition (RCR/RSC)
Ant-Skid
Wind
Drag
Increased Rotation Speed
Refusal Speed (VREF/V1)
Based on runway available
Maximum speed to which the airplane can accelerate at takeoff power and stop within remainder of the runway with:
- Two symetric engines in reverse
- One engine feathered
- One engine in ground idle
- Maximum anti-skid braking
A function of temperature and pressure altitude.
Critical Engine Failure Speed (VCEF)
Based on CFL
Speed to which plane can accelerate, lose an engine, and either continue the takeoff with remaining engines or stop in the same runway distance`
A function of temperature, pressure altitude, weight, and CFL.
One-Engine-Inop Air Minimum Control Speed (VMCA)
Airspeed at which, when critical engine fails, it is possible to maintain straight and level flight with AOB not to exceed 5 degrees.
Percent Mean Aerodynamic Cord (MAC)
A value that relates to center of gravity.
Operating Area
Based on fuel and cargo weight/ arm, refers to the load (Gs) that may be imposed.
There are four operating areas
Two Engine Inoperative Air Minimum Control Speed (VMCA2)
Second critical engine suddenly made inop and able to still maintain straight flight with AOB less than 5 degrees.
VMCA2 Conditions
Conditions:
o Eng 1 and 2 failed, props feathered or windmilling
o T/O power on all remaining engines
o Max rudder deflection (limited by 150 pounds of pedal force)
o Flaps 50
o Min T/O Weight
o 5 degree AOB award from failed engines
o Rudder trim for 3 degree appr w/ 3 engines
o Gear up or down
VT/O: Takeoff Speed:
The speed at which the aircraft leaves the ground. Normally scheduled to ensure that VT/O is greater than VMCA. Takeoff ground run is the distance from brakes release to this speed.
VR: Rotation Speed
The speed at which the pilot initiates the change in aircraft attitude with the intention of leaving the ground. Norm scheduled to ensure that VT/O is greater than VMCA.
A function of temperature, pressure altitude and weight.
VOBS: Obstacle Clearance Speed
With an engine failure, VOBS is the target speed to capture and fly until pitch attitude and rate of climb can be reduced allowing the airplane to accelerate to flap retraction speed. A function of temperature, pressure altitude and weight
RCR/RSC
- Runway Condition Reading (RCR) is a measure of tire-to-runway friction coefficient.
- RCR is given as a whole number.
- Define the braking characteristics for various runway surface conditions.
- Runway Surface Condition (RSC) is the average depth covering the runway surface measured to 1/10 inch (1 inch is equivalent to a RSC of 10)
VMCG
Ground Minimum Control Speed:
Minimum airspeed during the takeoff roll at which when the critical outboard engine is suddenly made inoperative, it is possible to maintain control using rudder control alone and safely continue the takeoff using normal piloting skills.
Engine fail up to VMCG, the plane will deviate 30ft on dry runway.
Above VMCG will lessen deviation
High Speed Cruise (HSC)
Best Distance/Time
Bad for FF and wear on the aircraft
Long Range Cruise (LRC)
Profile speed slightly faster than maximum range that provides 99% of the maximum specific range.
Max speed for minimum power required.
Maximum Endurance (END)
Speed that provided minimum fuel flow with flaps up.
