Performance Basics Handout v2 - AeroNews · To achieve the minimum climb gradient ... Balked Landing CS 23.77 (a) Minimum climb gradient 3,3% at Sea Level ... Performance_Basics_Handout_v2.ppt

Handout

Performance Basics

Flight Training Division

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© Peter Schmidleitner

Characteristic Speeds



VMC

VYSE

For Twins


VS (s1): Stalling SpeedVSO: Stalling Speed in landing configurationVX: Best Angle-of-Climb SpeedVY: Best Rate-of-Climb SpeedVFE: Max. Speed „Flaps extended“VLE: Max. Landing Gear Extended SpeedVLO: Max. Landing Gear Operating SpeedVA: Manoeuvering SpeedVNO: Max. Cruising SpeedVNE: Never Exceed Speed



VX: Best Angle-of-Climb(best ratio of „height gained“ to „distance flown“)

Consideration: Obstacle



VY: Best Rate-of-Climb(best gain of height within a given time)

Consideration: to gain height in the shortesttime



Height

Distance

VXVY

VCLB

MAX ANGLE CLIMB

MAX RATECLIMB

CRUISECLIMB

Compromise between speed and height


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VA: Manoeuvering speedMaximum „flaps up“ speed in a steep turn.(Below VA and with flaps retracted the aircraft structure cannot beoverstressed.)

Usually also defined as:Full or abrupt control surface movement not permissible abovethis speed.Maximum speed in heavy turbulence.



VA: Manoeuvering speed

Maneuvering speed means the wing is supposedto stall

before it produces enough Gs to break

any part of the airplane.



Manoeuvering EnvelopeLoad Factor

Speed

0 g

1 g

Stall area

Stall area

Vs

VA VNO VNE


Manoeuvering Speed VA

?VA not indicated on the ASI !


VNO: Max. Structural Cruising SpeedMaximum speed in cruiseAbove VNO the permissible gust load is reduced; thereforeVNO should be exceeded in smooth air only.



VNE: Never Exceed SpeedMust not be exceeded in any operation!


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Density Altitude


Density Altitude

Density Altitude:Altitude in the Standard Atmosphere(ISA) at which the air density is equalto the current air density.What the aircraft really „feels“ is theDensity Altitude.


Density Altitude Diagram


„Koch Chart“

Sea Level, Std Temp


„Koch Chart“

Mariazell, 2820ft 30° C


Rules of Thumb

1° C = 120 ft(or 100 ft for a „quick calculation“)

- 1 hPa = Altitude + 30 ft1000 ft Altitude = TAS + 2%

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Take-off and LandingPerformance


Take-off Performance

What do we want?



To stop on the runway if take-off has to be abandoned



To clear the runway end at the specified„screen height“ when the take-off iscontinued



To achieve the minimum climb gradientprescribed by regulations



To clear the obstacles in the climb path

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Therefore the Maximum Take-off weightis determined by

Runway lengthMust be sufficient for

a rejected take-off (accelerate stop distance)a continued take-off (take off distance)

Minimum climb gradientObstacle climb gradient


TKOF run / TKOF distance

required screen height

TKOF run

TKOF distance


RWY Contamination

WET affects braking action(Accelerate Stop Distance)

Contaminationaffects braking action(Accelerate Stop Distance)

ANDAcceleration(TKOF run/TKOF distance)


Landing Performance

required threshold height

LDG run

LDG distance


Weight and Balance


Determination of CG

Weight and Balance

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Limits of CG position

Weight and Balance


Weight and Balance

Graph to determine the loading moment


Limits of CG moment

Weight and Balance


Multi-engine considerations


Question:In an underpowered twin, what is the role of thesecond engine?

Answer:It doubles your chance of engine failure, and itwill fly you to the scene of the accident


1-eng climb performance

2 eng

1 eng1/2

1/2

Wrong !

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2 eng

1 eng

1/2

1/2

0 eng = glide



2 eng

1 eng

1/2

1/2

0 eng = glide



How serious is an engine failure ?It depends !

„Scale of seriousness“

1 10Hard to notice, hardly worth to notice

1 or 2

Extremely serious, immediate action required

10Unrecoverable

11Here you must be proficient


Engine fail – sequence of events

Asymmetric thrustYaw (heading changes)Slip After a while direction would changeUse rudder to counter the slip„step on the ball“Apply bank to avoid turning„raise the dead“


„Critical Engine“

The engine you most regret losing is called thecritical engine. In a twin where both engines rotate clockwise, that will be the left engine. Certification rules:

The „critical engine“ is producing a higher VMC speed. The „critical-inoperative-engine“ for performanceconsiderations is that engine which, wheninoperative, results in the lowest rate of climb.


Factors causing an engine to be the„critical engine“:

Helical propwashTwisted liftP-factor

„Critical Engine“

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The problems

AsymmetryControlPerformance


Asymmetry

offset thrust lineoffset drag lineP-factorwindmiling propeller drag


Control

rudder effectivenessfin/rudder stalleffect of bankfoot load and trimming


Performance

excess power availablesingle – engine ceilingzero - thrust


For Twin-engined aircraft:Vmc: Minimum control speedVSSE: Minimum control speed for trainingVXSE: Best Angle-of-Climb Speed, eng.outVYSE: Best Rate-of-Climb Speed, eng.out




VMC

VYSE

For Twins

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Minimum Control SpeedVMC


Importance of VMC

Vmc is important forcontrol

NOT for

performance!

Vmc guaranteesheading

NOT

climb or level flight!

Vmc

Vyse


Determination of VMC

The most unfavorable center of gravityThe aeroplane trimmed for takeoffThe maximum sea level takeoff weight or any lesserweight necessary to show VmcThe most critical takeoff configuration with landing gearretractedThe aeroplane airborne but not in ground effectInitially maximum available take-off power or thrust on the enginesOne engine inoperative and windmilling unless an autofeather system is installedVmc may not exceed 1.2 Vs1 determined at themaximum take-off weight


Performance Rules


Performance Requirements

Certification RequirementsOperational Requirements


Certification Requirements

ICAO: Annex 8No detailed rules, detailed rules onlyfor „Large Aeroplanes“

FAA: FAR 23JAA: JAR 23EASA: CS 23

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All the following is for„Light Twins“,

i.e. 2722 kg or lesswith a VS0 of 61 kts or below


CS 23 Requirements

General (CS 23.45)

Performance to be determined in followingconditions:

ISA, still airSea level up to 10.000 ftOAT STD up to STD + 30


CS 23 Requirements

SpeedsVR: min 1,05 VMC of 1,1 VS1, w.i.h.V at 50ft: highest of: 1,1 VMC

1,2 VS1

safe V withcritical engine failed

VREF: VMC *) or 1,3 VSO, w.i.h.*) flaps in highest TKOF setting


Take-off performance CS 23.53 (b)

Take-off distance (TOD): to be determined (all engines at TKOF PWR, TKOF Flaps, Gear down)

Accelerate stop distance (ASD): no requirement

1-eng out TKOF climb:no requirement

CS 23 Requirements


A practical hint

Since ASD is not published, you might consider

to add the take-off roll and the landing roll

or even better, to add the take-off distance and thelanding distance

Required RWY length

Required RWY length


CS 23 Requirements

Climb performance all engines CS 23.65 (a)

At Sea Level 8,4% withMax continuous power on both enginesGear upFlaps TKOFSpeed min 1,1 VMC or 1,2 VS1, w.i.h.

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CS 23 Requirements

Climb performance 1-eng out CS 23.67 (a)

At 5000ft withCritical engine featheredMax continuous powerGear upFlaps upSpeed min 1,2 VS1

No specific gradient required, steady climbor descent gradient to be determined


En-route climb / descent performanceCS 23.69

At each weight, altitude and temperatureall engines and 1-eng outmax continuous powergear up, flaps upMin speed:

all engines: 1,3 VS11-eng out: 1,2 VS1

No specific gradient required, steady climbor descent gradient to be determined

CS 23 Requirements


Landing performance CS 23.73

Landing distance to be determinedfor ISA temperature at each weight and altitudewith 3° (5,2%) APCH angle to 50ft, constantconfiguration(higher APCH angle if demontrated to be safe)safe transition to balked LDG at 50ft with max. LDG weight must be possible

CS 23 Requirements


Balked Landing CS 23.77 (a)

Minimum climb gradient 3,3% at Sea LevelTKOF power both enginesGear downFlaps LDG or retracted within 2 seconds withoutaltitude lossVREF

CS 23 Requirements


Operational Requirements

ICAO: Annex 6For General Aviation: Part II

No detailed rules, only: operation must be in compliance with

airworthiness certificateState-of-registry limitationsnoise certification

JAA: JAR-OPSFor (Corporate) General Aviation: JAR-OPS 2

not yet published


JAR-OPS 1

For Commercial Aviation: JAR-OPS 1,Aeroplanes which are

Propeller drivenMAPSC max 9Weight < 5700 kg

are: Performance Class BBut: might have to be considered as single engine aeroplane!

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Why ?


Climb Requirements acc. App.1 to JAR-OPS 1.525 (b)

min 1,2 VS1VREFmin 1,2 VS1As achieved

at 50 ftMin 1,1 VMC or1,2 VS1, WIH

Speed

UPLDGUPTKOFTKOFFlaps

UPDOWNUPUPDOWN orretr. within 7“

Gear

Feathered/MCP

maxafter 8“

Feathered/MCP

Feathered/TKOFTKOFPower

0,75%2,5%0,75%positive4%Gradient

1500 ft1500 ft400 ft

1-engAll eng1-eng All eng

Landing climbTake-off climb


Standard Operating

Procedures


System knowledge SOPsSafe

operation


Handling of Emergencies


Basic Principle

First fly !... then handle

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„PPAA“

Power

Performance

Analysis

Action

Max power

Gear? Flaps? Minimum speed?Identify engineverify engineFeather, shut down


The 3-5-4 Rule

3: airspeed, ball, needle

5: mixture, prop, throttle, gear, flaps

4: identify, verify, feather, secure


The 3-5-4 Rule




FLY !

Handle !


The 3-5-4 Rule




Power Performance

Analysis Action

Thank you for yourattention!

Documents

Performance Basics Handout v2 - AeroNews · To achieve the minimum climb gradient ... Balked Landing CS 23.77 (a) Minimum climb gradient 3,3% at Sea Level ... Performance_Basics_Handout_v2.ppt