ATPL Reference Book

e Aviation Theory Course for

rline Transport Pilot Compiled by Li Weidong Hao Jingsong He Qiuzhao

THE AVIATION THEORY COURSE FOR

Airline Transport Pilot Compiled by Li Weidong Hao Jingsong He Qiuzhao

Southwest Jiaotong University Press Chengdu, China

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CONTENTS Chapter! Regulations······ ·· · · ·• ·••••••· •· •••••••• •·•••••••••• •••· ••· ••••••••••••••••••••••••• ••· •••• •· • 1 Section A Applicable Regulations •••••• ••• ••••·• ••• ••• •·• ·• · ••• · •• ••• ••• ••• ••••••••• ••• ••• ••• ••• ••• I Section B The ATP Ce.rtificate· •• · · · •••• •• •· · ••• ••• · · · · •• · •• ••• ••• · •• •• •••• ••• ••• • •• •· •• •• · •• · ········ I 2 Section C Flight Engineer Requirements SectionD Flight Attendants···························································· •·•··· ··· ··· ··· 3 Section E Experience and Training Requirements ••• · · · .. •••• •• ••••••• •••... · •• •••·•• ••• ••• •·• ... 4 SectionF Flight Crew Duty' Time Limits •• •· •• ••• •· •••• ••· · · · •· •••••·• •·• ••• ••• · · •••• ••· ••• ••· ·•• 6 SectionG Dispatching and Flight Release······················································ ···19 Section H Fuel Requirements····································································· ···20 Section I Carriage of Passengers and Cargo···································· ·••· ·••·••••· · · •••21 • •••• ••••••••••••• I l l ••••••••••••••••••••••••••••••••••••

Section J

Emergency Equipment and Operations ... •••••· · •••••••.. •••.. •••· ••.. •••• •••••....... 23

Chapter 2 Equipment, Navigation and Facilities · ·· ··· ·•• · •· · •• ••• ••• · ·· ••• · ·• · ·· · ·• ••• ·•• ••• •• · ••• 27 Section A Inoperative Eq_uipment ••• •••••• ••• ••• ••• ••• ••• ••• ·•• ••• ••• ·•• ••• ••• ••• ••• ••• ••• ••• ·•• ·•• 27 Section B Pitot-static lnstrllments············ •••·•• ··•·•· ·••·•• •••••• •••••• ••• ••• ••••••••• ••••••·•• 27 Section C Safety of Flight Equipment ••· ••• •••· •• ••• ••• · •• ••• ••• ••• ••· ••• · •· · ·• · ·• ••• · •• ••• ••• ••• 30 SectionD Communications ••• ··• •• •••• · •• ·•· ••• ••• •• ••·• ••• ••• ••• ••• · •• ••• ••• · ••• •· ••• ••• · •· ••• ••• 32 Section E Navigation Equipment ••·••••••••••••••••••••••••••• ·•••••••••••••••••••• ···············32 Section F Horizontal Situ.ation Indicator ·•• ••• ••• •· · •· · · · · ·•· ••• ••• ••• ••••• •••• ••• ••• ••• ••• •·• ••· 34 Section G Radio Magnetic Indicator (R.MI) ••••••••• ••• ••••••••• ••••••••••••••••••••• ••• ••••••••• 37 Section H Long Range Navigation Systems ••• ••• ••• ••• ••• ••· ••• ••• ••• ••• ••• ••• ••• ••• •·• ••• ••• •·• 38 Section I Approach Systems··· ·····································································39 Section J Global Positioning System ••• •••••••••••••••••••••..••••.••••• ••••..••..•••••••••••••• 43 Section K Airport Lighting an.d Marking ••• •••••• •·••· •••· ••••••· •••••••••••••· •••••••·• ·••••••••44 Section L Approach Lighting ........................................................................ 47 Chapter3 Aerodynamics •••· •• ••• ••• ••• ••• ••• ••• ••• ••• · ••••• ••• •· · • •• ••• ••• •••• •• ••• ••• ••• ••· ••· •• · · •• 49 Section A Lift and Drag .••.••••••••••••••••••.•••••••.•••••.••.•.••••••••••••••••••.••••••••...••• 49 Section B Stability···················································································· 53 Section C Flight Controls · ·• ··· ··· ··• · ·• ·•• ••· •• · ••• · •• ••• ·•• ••• ••• ••• ••• •••·•• · ·• ••• · •• ••• ••• · ·····54 SectionD High-lift Devices ••• ••• ••• ••· •••••• ••• ·•• ••• ••• •••••• ••• · •• · •· •·• •·• · •· ••• ·•• •· •••• ••• ••• 56 ..•..•.•••••.••••.••••••.••.•••••.••.••..•....••......•••••••.•••••••.••.••••••••.••••• 57 Section E •••••••••.••.••••••.••.•.•••..••••••••••••••••••.•••••••••••..•.•......•..••••••••••••• 58 Section F

SectionG High Speed Fligh.t· •• ••• ••• ••• ••• ••• ••• · •• •• · ••• ••• ••· ••• ••• ••• •· •· •• · ·• · · · · · · ••• ••• ······59

Chapter 4

Perfonnance · · · · · · · · · ·· · · · · · · · ·· · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·· · · · · · · · · · · · ·· · · · · .. · · · 6 I

Section A Section B Section C Section D Section E

Engine performance ... ·· · · · · · · · · · · · · · · ·· ·· · · · · · · · · · · · · · · · · · · · · · · .. ·· · · · · · · · · ·· · ·· · ·· · · · · Take-off Perforn1ance ·· · · · · · · · · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·· · · · · · · · · · · · · · · ·· · ·· · · · Climb Performance · · · · · · .. · · ·· · · · · · ·· · · · · · · · · · · · · · · · · · · · · · · · · .. · · · · · · · · · · · · · · · ·· · ··· ·· · Cruise Perforn1ance · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · .. · · ·· · · · · · · ·· · ·· · · · · · · · Landing Performance ............ ......................................................

61 64 78 90 91

Section F

Miscellaneous Perforn1ance ......... .......... .. ............................ ........ 103

Section G Engine-out Procedures · .. · .. · · · .. · · · · · · .... · · .... · · · · · · · · · ·· · · · .............. ·· · · · · · · 108 Section H Flight Planning Graphs and Tables · ·· · · · · · · .. · .. · · · · · .. · .. · ............ · · · · · · ·· · · · Ill Section I Typical Flight Logs ............ ·· .... · ........... ·.... · ...... · .... · .. ·.... ·.......... 115 Chapter 5 Weight and Balance ...................................... · .......................... · ... 132 Section A Introduction .................. ......................................................... 132 Section B Weight and Balance Principle ................................. ..................... 133 Section C Center of Gravity Computation and Stabilizer Trim Setting"· .... ·········· ... · 137 Section D Changing Loading Condition ......................................................... 148 Section E Floor Loading Limits ....... .. ............................................. ............ 150 Chapter6 FlightOperations ...................................................... .................. 151 Section A Section B Section C Section D Section E

Airspaces .. · .. · .............. · .... · · · · .... · .... · · .. · .. · .. ...... · .. ........ · .. · · .... · .. · NOTAMs (Notices To Airmen) ....................... · .................. · .... ·...... Items on the Flight Plan .................................................... ........... Selecting an Alternate Airport ......... .................. ........................... ATC Clearances.................................... ....................................

151 152 154 156 158

Section F Take-off Procedures ........ · .. · .. · ........ · ..................... .... · .... .. · .. · .. · .. · 159 Section G Instrument Approaches ............................................................... 161 Section H Landing..................................... ............................................ 168 Section I Section J Section K Section L

Communications ..................................................................... Speed Adjustments . .. ............................................................... Holding ...... · .. · .... · · .. · .... · .. · .... · ...... · ........ · .. · ........ · ........ · · .... · ·.... · Charts for Instrument Flight .... · · .......... · .................... ·.... .............. ·

168 169 170 173

Chapter 7 Emergency, Physiology and Crew Resource Management...... ·................. 196 Section A Flight Emergency and Hazards...................................................... 196 Section B Flight Physiology · .... · .. · .. · · .. · .......... · ........ · ...... · .... · · .... · · ........ ··· .. · 209 Section C Situation Awareness, Communication, Leadership and Decision Making .. · .. · 224 Chapter 8 Aviation Meteorology .. · .... · .................. · ...... · .. · ................... · ...... ...

236

Section A Basic Theories ...... · · ................... · ........ · .............. ...... · .... · .. · ·.... · 236 Section B Hazard Weather. .. · .... · .. · ... ·.................... · .......... ·· ........ · ........ · .... · 256 Section C Aviation Weather Services .................... · .. · ............ ·........ ·........ ... 275 Appendix ..................... ............ .................................... ...... .....................

315

References .. · · .. .. · .. · ·· · · .. · .... · .. · .. · .............. · ...... · · · .. · .. · .. · · .. · · · .. · .. · ·.... · .............. · 319 2

REFERENCES 1 fiii~•.~ Et!.-TW:-l\.d: wm30!*~wJt&tl. 2002 2 .:£1jl!l.~~.d: wm30i*~iliJt&l±, 2001

3 4 5 6 7 8 9 10 11 12

13 14 15 16 17 18 19

~Ni;.~filjmNi:RJ . tJ:I IE ~ffl~ HNi:1Jl1lt~tJ?-: ~IN ~Aiitlill&tl

Airbus 320 FCOM. Airbus Industry/Flight Safety, 1998 Airline Transportation Pilot test Prep 2004. ASA, Inc, 2003 Instrument Flying Handbook. ASA, Inc, 1980 Boeing 737-300 Operating Manual Boeing Company, 1996 China Civil Aviation Regulations. Dale R Cundy, Rick S Brown. Introduction to Avionics. The Prentice--Hall, 1997 EHJ Pallett Aircraft Instruments & Integrated System. Longman Group UK Limited, 1992 FAA. Airman's Information ManuaL 1994 Harry W Orlady, Linda M Orlady. Human Factors in Multi-Crew Flight Operations. Ashgate Publishing Ltd, 1999 Ian B Suren. Aeroplane Perfonnance, Planning & Loading for the Transport Pilot. Aviation Theory Centre Pty Ltd, 1998 J Powell. Aircraft Radio Systems. Pitman, 1986 Instrument/Commercial Manual. Jeppesen Sanderson. Inc, 1994 Private pilot manual. Jeppesen Sanderson. Inc, 1988 K D Campbell, M Bagshaw. Human Perfonnance and Limitations in Aviation. Second Edition. Blackwell Science Ltd, 1999 Martin B Bshelby. Aircraft Performance Theory and Practice. American Institute of Aeronautics and Astronautics, Inc, 2000 The Pilot's Reference to ATC Procedures and Phraseology. California: Reavco Publishing, 1992

319

PREFACE Congratulations on you to continue your pilot training and welcome to The Aviation Theory Course for Airline Transport Pilot. This book is designed as a textbook and a reference for the Civil Aviation Administration of China (CAAC) knowledge Test about Airline Transport Pilot License (ATPL). The important points are summarized in the course; it is based on the study/review concept of learning. So, it has been helping pilots prepare for the test with great success.

MAIN CONTENT All of the knowledge for the ATP is included here, and has been arranged into 8 chapters based on each subject matter. They are Chapter 1, Regulations; Chapter 2, Equipment, Navigation and Facilities; Chapter 3, Aerodynamics; Chapter 4, Performance; Chapter 5, Weight and Balance; Chapter 6, Flight Operations; Chapter 7, Flight Emergency and Hazards, Flight Physiology and Crew Resource Management; and Chapter 8, Meteorology and Weather Services. Each chapter includes main knowledge about the subject

USE OF THE COURSE Airman knowledge about ATP requires applicants to understand it. All of the knowledge is faced with ATPL examination. It is designed that user will have two sets of learning, understanding and reviewing the basic knowledge appropriately. The intent is that all applicants keep on eye on basic concepts, procedures and methods made from the whole chapters. These are important to ainnan for transport aircraft fly. Some of the information may seem basic. There are two reasons for this: Many prospective private and commercial pilots and instrument rating knowledge are learned before, so some review

is helpful; also, the airline transport knowledge is based on them but deeper than them. However, we are not going to cover all of the information, because the pilot's basic knowledge for initial pilot would be presumed up to know. If it has been a long time since you reviewed the knowledge requirements of the initial information, it might benefit you to review the Aeronautical Theory Course for Pilot (Chinese Edition, pressed by Southwest Jiaotong University Press, March, 2004).

This course is the key element in airman knowledge materials for ATPL. Although it can be studied alone, we still suggest the user to join the teaching training. You may get many more understanding from your instructors. You may learn from other materials such as CAAC aviation regulations, Flight courses and other teaching materials provided by ATP training organizations. Then, you will be excellent to pass the theory test for ATPL.

This introduction has implied a heavy emphasis on knowledge exams, but that is not our style as an instructor. What you need to know for the knowledge test represents less than the course text -

the rest is solid information you must study from the Chinese Civil Aviation

Regulations (CCAR, i.e. CCAR 61, CCAR 91 , CCAR 121 and so on) and other reference books. You will also note an emphasis on computer-based training system (CBT). Most pilots are to some extent technically oriented, and it is estimated that well over all pilots use airline computers for flight planning, acquiring weather information, maintaining their logbooks, etc. Accordingly, we have included access information wherever it is appropriate. As CBT surfers know. if you can find one-by-one question showed on the computer, then you choice only one correct answer for the question with clicking the mouse button. And then you will get hold of all of the ATP knowledge gradually. Finally, we shall give thanks to the writers of this course; they are Ma Zhigang, L uo Jun, Hao Jingsong, Wei Lin, Liu Duhui, Xiang Xiaojun, Yang Junli, Fang Xuedong, Jiang Bo, He Qiuzhao,

Li Weidong, Mou Haiying, Huang Yifang, Zou Bo and Chen Huizhi. This course is compiled by Li Weidong, Hao Jingsong and He Qiuzhao. All of the writers are the experts about a\iation theory and come from the Civil Aviation Flight University of China. We believe it is a great contribution for CAAC. We wish this book will provide a good reference to you. We are confident that \\ith proper use of this book, you will score very well on any of the Airline Transport Pilot tests.

CHAPTER 1 REGULATIONS SECTION A

APPLICABLE REGULATIONS

"CCAR" is used as the acronym for "China Civil Aviation Regulations". Those regulations or rules are very important for operations of aircraft, and other aspects in that field. The regulations change frequently, and answer all questions in compliance with the most current regulations. Two different China Civil Aviation Regulations can apply to operations of aircraft covered by this chapter: CCAR 91, 121. CCAR 91 encompasses the general operations and flight rules for all aircraft operating within the Peoples' Republic of China. Often the rules of CCAR 121 supplement or even supersede CCAR 91. When an aircraft is not operated for compensation, only the CCAR 91 rules apply. For the test, assume CCAR 121 rules apply unless the question specifically states otherwise. CCAR 121 applies to air carriers (airlines) engaged in China or overseas air transportation. Carriers which operate under CCAR 121 are engaged in common carriage. This means that they offer their services to the public and receive compensation for those services. CCAR 121 operators are subdivided into three categories. Carriers authorized to conduct scheduled operations within China are domestic air carriers. Flag carriers conduct scheduled operations inside and outside China A supplemental carrier conducts its operations anywhere that its operations specifications permit but only on a non-scheduled basis. There is a fourth category, commercial operators of large aircraft, but they must comply with the rules covering supplemental carrier and the distinction is unimportant to this discussion. Other parts of the regulations apply as well. CCAR 61 governs certifications of pilots and fl ight instructors. CCAR 67 covers the issuing and standards for medical certificates. CCAR 65 prescribes the requirements for issuing certificates and associated ratings and the general operating rules for the holders of those certificates and ratings.

SECTION 8

THE ATP CERTIFICATE

The pilot-in-command of an air carrier flight must hold an Airline Transport Pilot (ATP) certificate with the appropriate type rating. The co-pilot on an air carrier flight that requires only

two pilots need only hold a Commercial Pilot certificate (with an Instrument rating) with the appropriate category and cl$5 ratings. A person must hold a type rating to act as pilot-in-command of a large aircraft (over 5 700 kg gross take-off weight), or of a mrbojet-powered airplane. Any type rating(s) on the pilot certificate of an applicant who successfully complete an ATP checkride will be included on the ATP Certificate with the privileges and limitations of the ATP Certificate, provided the applicant passes the checkrjde in the same category and class of aircraft for which the applicant holds the type rating(s). However, if a type rating for that category and class of aircraft on the superseded pilot certificate is limited to VFR, that limitation will be carried forward to the person's ATP Certificate level. An airline transport pilot may instruct other pilots in air transportation service in aircraft of the category, class and type for which he/she is rated. However, the ATP may not instruct for more than

8 hours in one day. A person who has lost an Airman's Certificate may obtain a temporary certificate from the CAAC. The temporary certificate is valid no more than 120 days. A crewmember is a person assigned to duty in the aircraft during flight This includes pilots, flight engineers, navigators, flight attendants or anyone else assigned to duty in the airplane. A flight crewmember is a pilot, flight engineer or flight navigator assigned to duty in the aircraft during flight No person may serve as a pilot on an air carrier after that person has reached his/her 60th birthday. Note that this rule applies to any pilot position in the aircraft, but it does not apply to other flight crew positions such as flight engineer or navigator. To exercise ATP privileges (such as pilot-in-command of an air carrier flight) a pilot must hold a First-Class Medical Certificate issued within the preceding 6 or 12 calendar months. To exercise commercial pilot privileges (e.g., co-pilot on a two-pilot air carrier flight) a pilot must hold either a First- or Second-Class Medical Certificate issued within the preceding 12 or 24 calendar months. The applicant is not required to hold a medical certificate when taking a test or check for a certificate, rating, or authorization conducted in a flight simulator or flight trainillg device.

SECTION C

FLIGHT ENGINEER REQUIREMENTS

Many air carrier aircraft have a flight engineer as a required flight crewmember. The aircraft "type certificate" states whether or not a flight engineer is required. On each flight requiring a flight engineer at least one flight crewmember, other than the flight engineer, must be qualified to provide emergency performance of the flight engineer's functions for the safe completion of the flight if the flight engineer becomes ill or is otherwise incapacitated. A pilot need not hold a Flight Engineer's Certificate to perform the flight engineer's functions in such a situation.

2

SECTION D

FLIGHT ATTENDANTS

One or more flight attendants are required on each passenger-carrying airplane that has more than 19 passenger seats. The number of flight attendants is determined by the number of installed passenger seats - not by the actual number of passengers on board. Each certificate holder shall provide at least the minimum number of flight attendants on each passenger-carrying airplane. For airplanes having a seating capacity of more than 20 but less than 50 passengers: at least one flight attendant. For airplanes having a seating capacity of more than 51 but less than 100 passengers: at least two flight attendants. For airplanes having a seating capacity of more than 100 passengers: at least two flight attendants plus one additional flight attendant for each unit (or part of a unit) of 50 passenger seats above a seating capacity of 100 passengers. If, in conducting the emergency evacuation demonstration required under CCAR 121, the certificate holder used more flight attendants than is required under the paragraph above of this section for the maximum seating capacity of the airplane, he may not, thereafter, take off that airplane in its maximum seating capacity configuration with fewer flight attendants than the number used during the emergency evacuation demonstration; or in any reduced seating capacity configuration with fewer flight attendants than the number required by the paragraph above of this section for that seating capacity plus the number of flight attendants used during the emergency evacuation demonstration that were in excess of those required under the paragraph above ofthis section. The number of flight attendants approved under the paragraphs above of this section is set forth in the certificate holder's operations specifications. During take-off and landing, flight attendants required by this section shall be located as near as practicable to required floor level exists and shall be uniformly distributed throughout the airplane in order to provide the most effective egress of passengers in event of an emergency evacuation. During taxi, flight attendants required by this section must remain at their duty stations with safety belts and shoulder harnesses fastened except to perform duties related to the safety of the airplane and its occupants. At stops where passengers remain on board, and on the airplane for which a flight attendant is not required by CCAR 121, the certificate holder must ensure that a person who is qualified in the emergency evacuation procedures for the airplane as required in CCAR 121, and who is identified to the passengers, remains on board the airplane, or nearby the airplane, in a position to adequately monitor passenger safety; and the airplane engines are shut down; and at least one floor level exit remains open to provide for the deplaning of passengers. On each airplane for which flight attendants are required by CCAR 121, but the number of flight attendants remaining aboard is fewer than required by CCAR 121, the certificate holder shall ensure that the airplane engines are shut down, and at least one floor level exit remains open to provide for the deplaning of passengers; and the number of flight attendants on board is at least half the number required by CCAR 121, rounded down to the next lower number in the case of fractions, but never fewer than one. The certificate holder may substitute for the required flight attendants

3

other persons qualified in the emergency evacuation proced:!:res fir th:!:t .,.;- ~t'a.l.~ as required in CCAR 121, if these persons are identified to the passengers If~ roe :.~ a:tendant or other qualified person is on board during a stop, that flight anendant or 0Stallad

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Figure 2-7 MIS Coverage Areas

The front azimuth coverage extends: A. Laterally, at least 40° on either side of the runway; B. In elevation, up to an angle of 15° and to at least 20 000 feet; C. In range, to a distance of at least 20 NM. The back azimuth provides coverage as follows: A. Laterally, at least 40° on either side of the runway; B. In elevation, up to an angle of 15°; C. In range, to a distance of at least 7 NM from the runway stop end. The MLS provides precision navigation guidance for exact alignment and descent of aircraft on approach to a runway. It provides azimuth, elevation, and distance. Standard MLS configuration can be expanded by adding one or more of three following functions or characteristics: back azimuth, auxiliary data transmissions, and larger proportional guidance. The MLS back azimuth transmitter is essentially the same as the approach azimuth transmitter. However, the equipment transmits at a somewhat lower data rate because the guidance accuracy requirements are not as stringent as for the landing approach. A great deal of data can be transmitted over the MLS. This includes MLS status, airport conditions and weather. The MLS has capability which allows curved and segmented approaches, selectable glide path angles, accurate 3-D positioning of the aircraft in space, and the establishment of boundaries to ensure clearance from obstructions in the terminal area 42

s::CTION J GLOBAL POSITIONING SYSTEM :he Global Positioning System (GPS) is a satellite-based radio navigational, positioning, and ::ansfer system. The GPS receiver verifies the integrity (usability) of the signals received form ~-= .";PS constellation through RAIM, to determine if a satellite is providing corrupted information. - ::.:Jut RAIM capability, the pilot has no assurance of the accuracy of the GPS position. TfRAIM ..... -:: available, another type of navigation and approach system must be used, another destination

=--=

- -=~ted, or the trip delayed until RAIM is predicted to be available on arrival. The authorization to _.: GPS to fly instrument approaches is limited to U.S airspace. The use of GPS in any other -:;-ace must be expressly authorized by the FAA Administrator. If a visual descent point (VDP) is published, it will not be included in the sequence of .. ::.-points. Pilots are expected to use normal piloting techniques for beginning the visual descent. :- ; database may not contain all of the transitions or departures from all runways and some GPS -e-:eivers do not contain DPS in the database. The GPS receiver must be set to terminal (±1 NM) : ..rse deviation indicator (COl) sensitivity and the navigation routes contained in the database in -:er to fly published IFR charted departures and DPS. Terminal RAIM should be automatically :-:vided by the receiver. Terminal RAIM for departure may mot be available unless the waypoints .:! part of the active flight plan rather than proceeding direct to the flfSt destination. Overriding an :...:.Jmatically selected sensitivity during an approach will cancel the mode annunciation. The RAIM

== CDI sensitivity will not ramp down, and the pilot should not descend to lviDA, but fly to the

- ssed approach waypoint (MAWP) and execute a missed approach. It is necessary that helicopter procedures be flown at 70 knots or less since helicopter departure :-:-cedures and missed approaches use a 20:1 obstacle clearance surface (OCS), which is double the :: ;;d-wing OCS, and turning areas are based on this speed as well. The GPS operation must be conducted in accordance with the FAA-approved aircraft flight ~'1ual (AFM) or flight manual supplement Flight crewmembers must be thoroughly fan1iliar with :e particular GPS equipment installed in the aircraft, the receiver operation manual, and the AFM _- flight manual supplement. Air carrier and the commercial operators must meet the appropriate ;:Jvisions of their approved operations specifications. The pilot must be thoroughly familiar with the activation procedure for the particular GPS ·t.:eiver installed in the aircraft and must initiate appropriate action after the MAWP. Activating the =:ssed approach prior to the MAWP will cause CDI sensitivity to immediately change to terminal =: )JM) sensitivity and the receiver will continue to navigate to the MAWP. The receiver will not : _Jt action to sequence past the MAWP. Turns should not begin prior to the MAWP. A GPS missed !::;roach requires pilot action to sequence the receiver past the MAWP to the missed approach :.: :tion of the procedure. If the missed approach is not activated, the GPS receiver will display an : .::ension of the inbound final approach course and the ATD will increase from the MAWP until it is - ~.,ually sequenced after crossing the MAWP. 43

Any required alternate airport must have approved instrument approach procedure other than GPS, which is anticipated to be operational and available at the estimated time of arrival and with which the aircraft is equipped to fly. Missed approach routings in which the track is via a course rather than direct to the next waypoint require additional action by the pilot to set the course. Being familiar with all of the inputs required is especially.critical during this phase of flight Properly certified GPS equipment may be used as a supplemental means ofiFR navigation for domestic en route, terminal operations and certain instrument approach procedures (lAPS). This approval permits the use of GPS in a manner that is consistent with current navigation requirements as well as approved air carrier operations specifications. Use of a GPS for IFR requires that the avionics necessary to receive aU of the ground based facilities appropriate for the route to the destination airport and any required alternate airport must be installed and operational.

SECTION K AIRPORT LIGHTING AND MARKING A rotating beacon not only aids in locating an airport at night or in low visibility, but also helps to identify which airport is seen. Civilian airports have a beacon that alternately flashes green and white. A military airport has the same green and white beacon but the white beam is split to give a dual flash of white. A lighted heliport has a green, yellow and white beacon. Figure 2-8 shows the basic marking and lighting for a runway with a non-precision approach. The threshold is marked with 4 stripes on either side of the centerline. 1 000 feet from the threshold, a broad "fiXed distance.. marker is painted on either side ofthe centerline (A). The runway lights are white for the entire length ofthe runway (as are the centerline lights if installed). The threshold Is lit with red lights. A

.

OO

QO

~

--Y"'Ia•w

r)

0

Figure 2-8

0

C.'

-. =· -. - . -=·.

OOOuOvOOfll)

0

0

0

0

0

-

0

0

0

')

()

Basic Marking and Lighting for a Ruoway

Figure 2-9 shows the somewhat more elaborate ICAO marking for a non-precision runway. In addition to the fixed distance marker, there are stripes painted on the runway every 500 feet to a distance of 3 000 feet from the threshold. This runway has either high intensity runway lights (HIRL) or medium intensity runway lights (MIRL) installed. These lights are amber rather than white in the areas within 2 000 feet of the threshold. This gives the pilot a "caution zone" on 44

N u,httnn~ -

Ap;-.t:.xun:ne

r

9

o

r:>

O



G>

C

B

I (;

. . •

• •

4

tl

0

c

•

¢

«:

c:

C'

0

Figure 2-9 ICAO Marking for a Non-precision Runway ~

;·ze 2-10 shows the lighting and marking for a precision instrument runway. The runway

-:-: - ·~ has been modified to make it easier to fell exactly how much runway remains. The stripes _-: :-__ at 500 feet intervals for the 3 000 feet from the threshold. The HIRL or MIRL turns amber

· ::- = 2 000 feet closest to the threshold. The centerline lighting has alternating red and white =·:: :::om 3 000 feet to 1 000 feet to go, and has all red lights in the 1 000 feet closest to the -.:-: :.::•id. A

..,.,

..,..,.,..,....,

c

8 :)

0

0

-

t

0

' o-nloltll,...,hll

ovn..

,..

~,

........

0 .....

T

o I o

--o o

0

--o o

o l

- ...... - ..... -

Cl

::.: a..:d far bars is normally (114t higher. This higher glide path is intended for use only by high

::.:cc : aircraft to provide a sufficient threshold crossing height •.!.

::-!-color VASI consists of one light projector with three colors: red, green and amber. A

....... _:-- T.dication is amber, an "on glide slope" is green and a "low" is red. A tri-color VASI can be ~

:::: ~distance of 1/2 to 1 mile in daylight and up to 5 miles at night.

--e Precision Approach Path indicator (PAPI) approach light system consists of a row of _ ;:.::5 perpendicular to the runway. Each light can be either red or white depending on the

47

aircraft's position relative to the glide slope. The glide slope indications of a PAPI are as follows: Hlgh Slightly high On glide path Slightly low

4 white lights 1 red, 3 white lights 2 red, 2 white lights 1 white, 3 red lights

Low 4red lights Pulsating visual approach slope indicators normally consist of a single light unit projecting a two-color visual approach path into the final approach area of the runway upon which the indicator is installed. The below glide path indication is normally pulsating red, and the above glide path indication is normally pulsating white. The "on glide path indication" for one type of system is a steady white light, while for another type system, the on glide path indication consists of an alternating red and white.

48

CHAPTER 3 AERODYNAMICS This chapter establishes the basic knowledge elements of aerodynamics. We have 7 parts: lift !::i drag, stability, flight controls, high-lift devices, tum, VMc and high speed flight.

SECTION A LIFT AND DRAG 3ERNOULLI 'S EQUATION Bernoulli's equation is effectively the explanation for how an airplane is able to fly. It is in ;:.ility a special case of the First Law of Thermodynamics. In other words, it states that Energy can ·v~ be created or destroyed. However, fortunately for those of us who like to fly, energy can be :.:·nverted from one form into another, 1 2pfl+P=Po

:ere:

kp'Vl-

Dynamic Pressure;

P- Static Pressure; Po- Total Pressure. Bernoulli's equation is simply a special case of the above equation. In the case of a fluid or gas, ::e potential energy is represented by the static pressure. The Kinetic energy is a function of the =otion of the air, and of course it's mass. It is generally more convenient to use the density of the 1:: as the mass representation. In words, Bernoulli's equation is usually stated "Static pressure plus dynamic pressure is .:onstant" When a gas is accelerated, its pressure decreases (see Figure 3-1). As the wing moves

Figure 3-1

Variation in Velocity and Pressure through a Venture

49

through the air, the air stream is divided, part of it flowing over one surface while the remainder flowing under the other surface. The air flowing over the upper cambered surface flow faster than the air over the opposite surface to reach the trailing edge. Thus the pressure on the upper wing surface is lower than that on the lower surface and lift is produced.

AIRFOILS An airfoil is a surface which provides aerodynamic force when it interacts with a moving stream of air. A wing generates a lifting force only when air is in motion about it. Some of the terms used to describe the wing, and the interaction of the airflow about it, are listed here. Leading edge - The part of airfoil meets the airflow ftrst. Trailing edge - This is the portion of the airfoil where the airflow over the upper surface rejoins the lower surface airflow. Chord line - The chord line is an imaginary straight line drawn through an airfoil from the lading edge to the trailing edge. Camber - The camber of an airfoil is the characteristic curve of its upper and lower surfaces. The upper camber is more pronounced, while the lower camber is comparatively flat. This causes the velocity of the airflow immediately above the wing to be much higher than that below the wing. Relative wind - This is the direction of the airflow with respect to the wing. If a wing moves forward horizontally, the relative wind moves backward horizontally. Relative wind is parallel to and opposite the flight path of the airplane.

ANGLE OF ATTACK Angle of attack must not be confused with an airplane's attitude in relation to the earth's surface, or with "angle of incidence" (the angle at which the wing is attached relative to the longitudinal axis of the airplane). Angle of attack is defined as the angle between the chord line of the wing. and the relative wind. The coefficient of lift is revealed to be the same at a given angle of attack, regardless of the velocity, air density, wing area, etc. Angle of attack has a large effect on the lift generated by a wing. During take-offs, the pilot applies as much thrust as possible to make the airplane roll along launch rail. But just before lifting off, the pilot "rotates" the aircraft. The nose of the airplane rises, increasing the angle of attack and producing the increased lift needed for take-off.

FOUR FORCES There are four forces acting on an airplane all the time in flight: weight, lift, drag and thrust If the airplane does not accelerate, then we know that the four forces add up to zero. Conversely, if the aircraft is accelerated, then the forces are not in balance. Thrust and drag act opposite each other and parallel to the relative wind. 50

- ·::g.•n is a force which acts down. The concept of weight in fact defmes the term "down". So, _ ~::ow what "down" means, then you understand the direction weight acts. Weight always acts ~:y toward the center of the earth, because it is caused by the downward pull of gravity. :..:..~ is a force which acts perpendicular to the relative wind within the plane of symmetry. --=-= 3 :1othing in the definition which requires lift to be opposite to weight. In fact in many cases ..- _ :-•.:•t opposite to weight The air flowing over the upper surface of the wing is deflected further l::i!::::. ::-..;t flowing across the lower surface and therefore is accelerated. Bernoulli's principle states ~ -.e:l a gas is accelerated, its pressure decreases. Thus the pressure on the upper wing surface is :-- :::an that on the lower surface and lift is produced, 1

L =CL·2 pV"·S

-::: : L -Lift;

CL- Coefficient of Lift; S- WingArea A: zero angle of attack, the

+1·0

~ .::e

on the upper surface of -::.= ·.ving is still less than ~=spheric, but the wing is ~ : _.:ing minimum lift. As the -:: :of attack is increased, the lift ~!.Jped by the wing increases :-::·: rrionately. This is true until -::e ~gle of attack exceeds a =:::::a! value, when the air flowing ~:: :he top of the wing breaks up ..::::: 3 rurbulent flow and the wing -..:o...5 (see Figure 3~2).

~·

.a·

-t12"

+18"

+20"

'"oaltlvea

Figure 3~2 Effect of Angle of Attack on CL Angle of attack and indicated ~peed determine the total lift. An increase in either indicated airspeed or angle of attack increases ··::... lift (up to the stalling angle of attack) and a decrease in either decreases total lift. To maintain "..:= same total lift (i.e. maintain level flight), a pilot has to change the angle of attack anytime .:.::cated airspeed is changed. For example, as indicated airspeed is decreased, the angle of attack =..st be increased to compensate for the Joss of lift. The relationship between indicated airspeed and _ ~ :or a given angle of attack involves the law of squares. If the angle of attack does not change, -~~ lift varies with the square of the indicated airspeed. For example, if the airspeed doubles, the _"': will increase by four times.

Indicated airspeed can be thought of as having two elements-the actual speed of the !..-plane through the air (true airspeed) and the density of the air. As altitude increases, air density ::-.:reases. To maintain the same indicated airspeed at altitude, an aircraft must fly at a higher true 51

airspeed. To produce the same amount of lift at altitude, a higher true airspeed is required for a given angle of attack. Drag is a force which acts in the same direction as the relative wind. But it is not necessarily opposite to thrust. The definition is the equivalent of saying that drag is a force in the opposite direction to flight. It is also true that drag is by definition at right angles to lift. A curve comparing total drag to parasite and induced drag reveals an airspeed at which drag is at a minimum value. At higher airspeeds, total drag increases because of increasing parasite drag. At lower airspeeds, induced drag increases which increases the total drag.

L/D RATIO Since the lift stays constant (equal to weight), the low point on the curve is the airspeed that produces the best lift to drag (LID) ratio. This point is referred to as LIDmax (see Figure 3-3). I Induced drag (Wl)

'I /

Drag

Figure 3-3 Effect of Change in Weight on Drag

A change in weight changes the LID curve. The amount of parasite drag is mainly a function of indicated airspeed. The amount of induced drag is a function of angle of attack. When an aircraft's weight is increased, any indicated airspeed will require a higher angle of attack to produce the required lift. This means that induced drag will increase with increases in weight while there will be little change in parasite drag.

STALL We know that we must increase coefficient of lift as we reduce velocity. But we also know that there is a maximum coefficient of lift value for any given airfoil. Thus, we can conclude that there will be a speed below which we can not fly. The definition of stall speed is: The minimum speed at which the aircraft can produce sufficient lift for level fljght. In this case, since we are specifying that we are also flying straight

_ we know that lift must equal weight Thus, we can make a special case definition that ~ =---

a::d level stall speed is the minimum speed at which the wings can produce lift equal to

-:: ;:: :-fthe airplane,

v.

-A

S1a1l-

~-=

I

2W

\j CLmax · P · S

;r - Weight; ::~x- maximum coefficient of lift; _., _air density;

5 -Wmgarea.. :-:-:ere are four factors detennining the stall speed of our airplane: weight. maximum - -::":::ient oflift, wing area, air density. .;. wing will always stall at the same angle of attack. The load factor, weight and density

_::-_ie will cause the stalling true airspeed to vary, but the stall angle of attack will always be the "';\"eight is in the denominator, therefore as weight increases so does the stall speed. We have : - . -;bly already guessed that, but now we can see that the relationship is between the stall speed !::.-:

:he square root of the weight. Thus, if the airplane weighs twice as much the stall speed will

.:: ~:ease

by the square root of two (1.41).

~aximum

coefficient of lift is in the numerator, therefore a higher maximum coefficient of lift

.: result in a lower stall speed. We can see why designers like wings with high max. lift . _~fficients. Wmg area is also in the numerator. Therefore, a larger wing is one of the easiest ways to give .:.:.. airplane a lower stall speed.

Air density is also in the numerator. Therefore, we lmow that the stall speed will increase as :..:e air density decreases. In other words, stall speed will increase as altitude increases.

SECTION 8

STABILITY

Stability refers to how an aircraft responds to changes in angle of attack, slip or bank. Control refers to the ability to initiate and sustain changes in angle of attack, slip or bank. In other words, stability and control are opposites.

An aircraft without sufficient stability will be difficult, even dangerous to fly. On the other hand, if the aircraft is so stable that it cannot be controlled that will also be dangerous.

STATIC STABILITY Static stability refers to the air.craft's initial response when disturbed from a given angle of attack, slip or bank. Positive static stability is an initial tendency to return to its original anirude of

53

equilibrium. When iL continues to diverge, it has ncgath c static SU!'tilit:•. If an aircraft tends to remain in its new disturbed state. it has neutral static stahilit:. \lost airplanes have positive static stability in pitch and ya\\, and arc clu!>c to neutrally ~tab!~ in roll. The ·.erticu.l tail is the primary source of direction stability (yaw). ami the horizontal tail is the: prima;:. source of pitch stability.

DYNAMIC STABIL ITY Dynamic stabil ity refers to the aircrafl. response over time v.hen disn!rbcd from a given nnglc of attack, slip or bank. Wl1en an aircraft is disturbed from equilibrium :..-.a :hen Lries ro return, it will invariably overshoot the original attitude and then pitch back. This rem:lS in a series of oscillations. If the oscillations become weak with time, the aircraft has positiYe dynami.: 5:.a~ilit:·. If the aircraft diverges further away from its original attitude with each oscillation. it has negative dynamic st1bility.

CENTER OF GRAVITY The center of gravity (CG) is by definition the point about which all gra; ltational moments add up to zero. If the CG is toward its rearward limit, the aircraft t-e le~s stable in both roll and pitch. As the CG i~ moved forward, the ~t.'lbility impnw~ s . E\·cm though an airplane \\ill be less stable with a rearward CG. it will have some desirable aerodynamic charam~ri~tics due to reduced aerodynamic loading of horizontal tail surface. This type of an airplane "iU h:m; a slightly lower c;tall speed and will cruise faster for a given power setting.

''ill

GROUND EFFECT When an aircraft flies in ground ciTeel, the ground interferes '' ith :.he tip \ Ol.>!:'\. This reduces the induced drag. If the wing Oev. right at ground level there would be no \One~~: all and thcretore a large reduction in induced drag. I his ground effect reduces induced dra; (and :_t..,ere•o:e total drug) and increases lif\. As an airplane nics out of ground ciTcct on take-off. the increased induced drag will require a higher angle of attack. The ground eflcct falls o1frapidl~ ''ith Jltirude

SECTION C

FLI GHT CONTROLS

lt is very dillicull to move the night control surfaces of jet aircraft with just me\:hanical and aerodynamic forces. Flight controls are usually mo,cd b) hydraulic actuators and divided into primary flight controls and secondary or atL'\iliru: night controls. The most common control arrangement on the conventional airplane is ailerons on th·e main wing for roll control and a horizontal tai l known as the stnbililcr with moveable elevators for pitch control. There is also a vertical fin with u rudder for directional or yaw control. ~econdary (or auxiliary) flight controls 54

include tabs, trailing-edge flaps, leading-edge flaps, spoile~; and slats.

ROLL CONTROL Roll Control is provided by the ailerons and flight spoilets. When the ailerons are deflected the down going aileron increases the camber of one wing. The up-going aileron decreases camber on the other wing. The result is an asymmetric lift betwee.n the wings. This causes the roll rate to increase away from the wing with the greater lift It is important to note that as long as a net moment (lift times distance) exists between the two wings the aircraft will roll faster and faster. The exact mhc of controls is determined by the aircraft's flight regime. In low speed flight all control surfaces op,!rate to provide the desired roll control. When the aircraft moves into higher speed operations, •control surface movement is reduced to provide approximately the same roll response to a given irtput through a wide range of speeds. Many aircraft have two sets of ailerons-inboard and outboard. The inboard ailerons operate in all flight regimes. The outboard ailerons work only when the wing flaps are extended and are automatically locked out when flaps are retracted. This makes good roll response in low speed flight with the flaps extended and prevents excessive roll and w ing bending at high speeds when the flaps :ll'e retracted.

SPOILERS The spoiler will disrupt (separate) the boundary layer, thereby increasing drag and "spoiling" .!ft on the part of the wing affected by the spoiler. If raised on only one wing, they aid roll control :y causing the lift of that wing drop. If the spoilers raise symmetrically in flight, the aircraft can =::her be slowed in level flight or can descend rapidly without an increase in airspeed. When the :?oilers rise on the ground at hlgh speeds, they destroy the wing's lift that puts more of the aircraft's \'eight on its wheels which makes the brakes more effective. Often aircraft have both flight and ground sr,oilers. The flight spoilers are available both in J ght and on the ground. However, the ground spoilers can only be raised when the weight of the l::'craft is on the landing gear. When the spoilers deploy on the ground, they decrease lift and make :.-:~ brakes more effective. In flight, a groun.d-sensing switch on the landing gear prevents : : ?loyment of the ground spoilers .

.QRTEX GENERATORS The vortex generators is designed to stic·k up out of the boundary layer into the free stream. It :::1erates turbulence which re-energizes the boundary layer and prevents flow separation and the .:.endant pressure drag (review drag as required). When located on the upper surface of a wing, the .::ex generators prevent shock-induced s•eparation from the wing as the aircraft approaches its =:!cal Mach number. This increases aileron effectiveness at high speeds.

55

TABS Another way of changing the amount of force the pilot must apply to the control column is through servo and anti-servo tabs. In this system the control column is directly connected to the control surface but a tab is geared to the movement of the control surface .so that it either assists the movement of the control, or counters the movement of the control. Thus, the controls can be made to feel heavier or lighter than they would otherwise. Servo tabs are on the trailing edge of the control surface and are mechanically linked to move opposite the direction of the surface. If the tab moves up, the surface moves down. The use of trimming tabs is one method of relieving aerodynamic load by means of a secondary control surface attached to tht~ end of the primary surface. Trimming tabs must be operated by a control mechanism in the required direction. This may be done manually by cables connected to a control wheel in cockpit, or electrically by servomotors attached to the cable. Trim tabs must be moved in the opposite direction to that of the primary control surface. Anti-servo tabs move in the same direction as the primary control surface (see Figure 3-4). This means that as the control surface deflects, the aerodynamic load is increased by movement of

the anti-servo tab. This helps to prevent the .control surface from moving to a full deflection. It al·;o makes a hydraulically-boosted flight com'rol more aerodynamically effective than it would otherwise be.

NOSE·UP PITCl1

NOSE-DOWN PITCH

Figure 3-4 Anti-servo Tabs Opposes Further Movement and Provides "Feel"

Some jet aircraft have control tabs for use in the event of loss of all hydraulic pressure. Movement of the control wheel moves the control 1t.ab which causes the aerodynamic movement of the control surface. The control tab is used only du•ring manual reversion, that is, with the loss of hydraulic pressure. They work the same as a servo ta1? but only in the manual mode.

SECTION 0

HIGH-LIFT DEVICES

Swept wing jet aircraft are equipped with some hig:h-lift devices including leading edge flaps, slots or slats, and trailing edge flaps. All of the high-lift devices are to increase lift at low airspeeds

56

~ :o

delay stall until a higher angle of attack.

-EADING EDGE DEVICES The two most common types of leading-edge devices are slats and Krueger flaps. The Krueger :":ap extends from the leading edge of the wing, increasing the camber of the wing. The slat also e:\."tends from the wing's leading edge but it creates a gap or slot This slot allows high energy from .:z1der the wing to flow over the top of the wing that delays stall to a higher angle of attack than would otherwise occur. It is common to find Krueger flaps and slats on the same wing.

TRAILING EDGE FLAPS The primary purpose of flaps is to increase the camber of the wing. A flap which increases the wing camber without forming a slot, as described below, is called a plain flap. A flap which moves back opening a slot when extended is called a fowler flap.

SECTION E TURN When an airplane is in a level turn it is in a state of acceleration. However, all the acceleration is confined to a plane parallel to the horizon. Therefore, the vertical component of the lift vector must completely balance the weight vector which is vertical by definition (see Figure 3-5). When the pilot rolls the airplane into a turn, he must increase the total lift of the wing so that the vertical component is equal to the airplane's weight by increasing the angle of attack. If no compensation is made for the loss of vertical component of lift in a turn, the aircraft will sink.

r?·· ····~

L

i w

w

w

30'

70'

Bank Angle

Bank Angle

Figure 3-5 Tile Steeper the Bank, the Greater the Lift Force Required from the Wings

Load factor is the ratio of the weight supported by the wings to the actual weight of the aircraft. On the ground or in unaccelerated flight the load factor is one. Conditions which can increase the load factor are vertical gusts (turbulence) and level turns. In a level turn, the load factor is dependent only on the angle of bank. Airspeed, turn rate or aircraft weight have no effect on load factor. Rate of turn is the number of degrees per second at which the aircraft turns, 57

w=~

v

T=21tL_ g tany

where: w- rate of tum; T- time to tum;

y- angle of bank; V - velocity.

The time to tum is proportional to velocity and inversely proportional to angle of bank. In other words, it takes longer time to tum at a high speed, but less time to turn at a large angle of bank.

R= -

v-

gtany

Radius of turn depends on three variables: g, velocity squared (V"), angle of bank. Notice in the development of the radius of turn equation that the weight (J¥) canceled out of the equation. This is a very important observation since it means that the size of the aircraft has no effect on the radius of tum. Thus, two aircraft flying at the same angle of bank and velocity will make the same radius of tum even if one is 1 000 times larger than the other. Radius of tum depends on velocity squared and is inversely proportional to the tangent of the angle of bank.

SECTION F VMc

P-FACTOR When the aircraft slows down, the angle of attack must increase. When this happens the plane of rotation of the propellers is no longer at right angles to the TAS. As a result the downgoing blade and upgoing blade on the propeller each operate at a different angle of attack. The downgoing blade will be at a greater angle of attack and therefore will produce more thrust (see Figure 3-6). 58

Relabv. Aknow UpgomQ Blade

Figure 3-6

Down Going Prop Blade Produces More Thrust with the Tail on the Ground

CRITICAL ENGINE Because of''P-Factor'' on most propeller-driven airplanes, the loss of one particular engine at high angles of attack would be more detrimental to performance than the loss of the other. One of the engines has its thrust line closer to the aircraft centerline. The loss of this engine would more adversely affect the performance and handling of the aircraft; therefore this is the "critical engine". For unsupercharged engines, VMc decreases as altitude is increased. Stalls should never be practiced with one engine inoperative because of the potential for loss of control. Engine out approaches and landings should be made the same as normal approaches and landings. Banking at least 5° into the good engine ensures that the airplane will be controllable at any speed above the certificated VMc, that the airplane will be in a minimum drag configuration for best climb performance, and that the stall characteristics will not be degraded. Engine out flight with the ball centered is never correct. The blue radial line on the airspeed indicator of a light, twin-engine airplane represent maximum single-engine rate of climb.

SECTION G HIGH SPEED FLIGHT

MACH NUMBER Mach number is the ratio of TAS and the speed of sound. Therefore, if you are traveling at exactly the speed of sound your Mach number is l.O. Mach 8 means your speed is 80 % of the speed of sound, etc. The drag increase largely when the air flows around the rurcraft exceeds the speed of sound (Mach 1.0). Because lift is generated by accelerating air across the upper surface of the wing, local air flow velocities will reach sonic speeds while the aircraft Mach number is still considerably below the speed of sound. With respect to Mach cruise control, flight speeds can be divided into three regimes-subsonic, transonic and supersonic. Subsonic-all flow evei)'Where on the rurcraft is less than the speed of sound. Transonic flow begin at critical Mach number and some but not all the local air flow velocities are Mach 1.0 or above. When all the local Mach numbers surrounding an aerofoil exceeds Mach 1.0, then the flow at that time is considered to be supersonic. In general tenns the subsonic band extends up to about Mach 0.75, the transonic regime between Mach 0.75 and Mach 1.20.

CRITICAL MACH NUMBER A limiting speed for a subsonic transport rurcraft is its critical Mach number (McRir). That is the speed at which air flow over the wing first reaches, but does not exceed, the speed of sound. At

59

MCRlr there may be sonic but no supersonic flow. The less airflow is accelerated across the wing, the higher the critical Mach number (i.e., the maximum flow velocity is closer to the aircraft's Mach number). Two ways of increasing MeRIT in jet transport designs are to give the wing a lower camber and increase wing sweep. A thin airfoil section (lower camber) causes less air flow acceleration. The sweptwing design has the effect of creating a thin airfoil section by inducing a span wise flow, thus increasing the effective chord length.

MACH TUCK As the aircraft moves into supersonic flight, the aerodynamic center and center of pressure, both move back. The nose of the aircraft always tends to pitch nose down as the aircraft transitions from subsonic to supersonic speed. This tendency is called the "Mach Tuck". This tendency is further aggravated in sweptwing aircraft because the center of pressure moves aft as the wing roots shock stall. When an airplane exceeds its critical Mach number, a shock wave forms on the wing surface that can cause a phenomenon known as shock stall. If the wing tips of a sweptwing airplane shock stall first, the wing's center of pressure would move inward and forward causing a pitch up motion. Although a sweptwing design gives an airplane a higher critical Mach number (and therefore a higher maximum cruise speed), it results in some undesirable flight characteristics. One of these is a reduced maximum coefficient of lift. This requires that sweptwing airplanes extensively employ high lift devices, such as slats and slotted flaps, to get acceptably low take-off and landing speeds. Another disadvantage of the sweptwing design is the tendency, at low airspeeds. for the wing tips to stall frrst. This results in loss of aileron control early in the stall: and in very little aerodynamic buffet on the tail surfaces. Dutch roll tendency is typical of sweptwing designs. If such an airplane yaws, the advancing wing is at a higher angle of attack and presents a greater span to the au- stream than the retreating wing. This causes the aircraft to roll in the direction of the initial yaw and simultaneously to reverse its direction ofyaw. When the yaw reverses, the airplane then reverses its direction of roll and yaw again. This roll-yaw coupling is usually damped out by the vertical stabilizer. But at high speeds and in turbulence, this may not be adequate, so most aircraft are also equipped with a yaw damper to help counteract any Dutch roll tendency.

60

CHAPTER 4 PERFORMANCE In the following chapter we will present the conception required to understand the performance of transportation aircrafts. Furthermore, this chapter will concentrate on the methods to calculate the performance of transportation aircrafts. The exams will include both conception test and method test. In the exams, all questions are single-choice test, in which you should ftnd out the only one right choice from three answers. In terms of an aircraft, performance can be defined as a measure of the ability of the aircraft to carry out a specified task. In this chapter the expression "performance" will be taken to refer to tasks relating to the flight path of the aircraft mostly rather than to those involving its stability, control or handling qualities. For a civil transport flight operation, the flight path consists of a number of elements, or maneuvers, which make up the total mission but which can be analyzed separately, these are, take-off, climb, cruise, descent and landing, with additional maneuvers such as turning or flying a holding pattern. Performance can be used as a measure of the capability of the aircraft in many ways. In the case of a civil transport aircraft it determines an element of the cost of the operation of the aircraft and hence it contributes to its economic viability as a transport vehicle. Performance can also be regarded as a measure of safety. Whil.st an aircraft has an excess of thrust over drag it can increase its energy by either climbing or accelerating; if the drag exceeds the thrust then it will be losing energy as it either decelerates or descends. In safe flight, the aircraft must not be committed to a decrease of energy that would endanger it so that, at all critical points in the mission, the thrus1 available must exceed the drag; this is a consideration of the performance aspect of the airworthiness of the aircraft. Airworthiness and performance are intimately associated. However, in any conflict between efficiency and flight safety the airworthiness criterion relating to the safety of the aircraft must be considered to be dominant In this chapter, we wiU mainly consider Part 25 of China Civil Aviation Regulations (CCAR 25) which is almost identical to Part 25 of the AmericaiJ counterpart of Federal Aviation Regulations (FAR 25), both of which relate to large civil transpor1 aircraft.

SECTION A ENGINE PERFORMANCE There are two basic forms of engine used for aircraft propulsion: the power-producing engine, 61

which produces shaft power that is then turned into a propulsive force by a propeller, and the thrust-producing engine, which produces its propulsive force directly by increasing the momentum ofthe airflow through the engine. Obviously, the power-producing engine includes both reciprocating engine and turboprop engine. Meanwhile, the usual form of thrust-producing engine is the turbojet engine, although rockets could be included in this category. The type of engine selected for a particular airplane design depends primarily on the speed range of the aircraft. The reciprocating engine is most efficient for aircraft with cruising speeds below 250 MPH (miles per hour), while the turboprop engine works best in the 250 MPH to 450 MPH range and the turbojet engine is most efficient above 450 MPH. Manifold pressure (MAP) is a measurement of the power output of a reciprocating engine. It is basically the pressure in the engine's air inlet system. In a normally-aspirated (unsupercharged) engine, the MAP will drop as the aircraft climbs to altitude. This severely limits a piston-powered airplane's altitude capability. Most piston-powered airplanes flown by air carriers are turbocharged. On this type of engine, exhaust gas from the engine is used as a power source for a compressor that in tum raises the MAP at any given altitude. The flow of exhaust gas to the turbocharger is controlled by a device called a waste gate. Turbocharging allows an aircraft to fly at much higher altitudes than it would be able to with normally-aspirated engines. The term critical altitude is used to describe the effect of turbocharging on the aircraft's performance. The critical altitude of a turbocharged reciprocating engine is the highest altitude at which a desired manifold pressure can be maintained. The pilots of reciprocating-engine-powered aircraft must be very careful to observe the published limits on manifold pressure and engine RPM. In particular, high RPM and low MAP can produce severe wear, fatigue and damage. Both turboprop engines and turbojet engines are types of gas turbine engines. All gas turbine engines consist of an air inlet section, a compressor section, the combustion section, the turbine section and the exhaust. Air enters the inlet at roughly ambient temperature and pressure. As i1 passes through the compressor the pressure increases and so does the temperature due to the heat o1 compression. Bleed air is tapped off the compressor for such accessories as air conditioning and thermal anti-icing. The section connecting the compressor and the combustion sections is called the diffuser. In the diffuser, the cross sectional area of the engine increases. This allows the air stream from the compressor to slow and its pressure to increase. In fact, the highest pressure in the engine is attainec at this point. Next, the air enters the combustion section where it is mixed with fuel and the mixture i! ignited. Note that there is no need for an ignition system that operates continuously (such as th( spark plugs in a piston engine) because the uninterrupted flow of fuel and air will sustair combustion after an initial "light off''. The combustion of the fuel-air mixture causes a grea

62

increase in volume and because there is higher pressure at the diffuser, the gas exits through the turbine section. The temperature of the gas rises rapidly as it passes from the front to the rear of the combustion section. It reaches its highest point in the engine at the turbine inlet. This turbine inlet temperature (TIT) is usually the limiting factor in the engine operation. In many engines, TIT is measured indirectly as exhaust gas temperature (EGT). The maximum turbine inlet temperature is a major limitation on turbojet performance, and without cooling, it could easily reach up to 4 000 op, far beyond the limits of the materials used in the turbine section. To keep the temperature down to an acceptable 1 100 "F to 1 500 "F, surplus cooling air from the compressor is mixed aft of the burners. The purpose of the turbine (s) is to drive the compressor (s) and they are connected by a drive shaft. Since the turbines take energy from the gas, both the temperature and pressure drop. The gases exit the turbine section at very high velocity into the tailpipe. The tailpipe is shaped so that the gas is accelerated even more, reaching maximum velocity as it exits into the atmosphere (see Figure 4-1 below).

o:s..

I F>J""I•' t aJ

He,..,.

Figure 4-1 Turbojet Engine

Combinations of slow airspeed and high engine RPM can cause a phenomenon in turbine engines called compressor stall. This occurs when the angle of attack of the engine's compressor blades becomes excessive and they stall. If a transient stall condition exists, the pilot will hear an intermittent "bang" as backfires and flow reversals in the compressor take place. If the transient condition develops into a steady state stall, the pilot will hear a loud roar and experience severe engine vibrations. The steady state compressor stall has the most potential for severe engine damage, which can occur literally within seconds of the onset ofthe stall. If a compressor stall occurs in flight, the pilot should reduce fuel flow, reduce the aircraft's angle of attack and increase airspeed. That means, recovery must be accomplished quickly by reducing throttle setting, lowering the airplane angle of attack, and increasing airspeed. The turboprop is a turbine engine that drives a conventional propeller. It can develop much more power per pound than can a piston engine and is more fuel efficient than the turbojet engine. Compared to a turbojet engine, it is limited to slower speeds and lower altitudes (25 000 feet to the tropopause). The term equivalent shaft horsepower (ESHP) is used to describe the total engine 63

output This term combines its output in shaft horsepower (used to drive the propeller) and the jet thrust it develops. As the density altitude is increased, engine performance will decrease. When the air becomes less dense, there is not as much oxygen available for combustion and the potential thrust output is decreased accordingly. Density altitude is increased by increasing the pressure altitude or by increasing the ambient temperature. Relative humidity will also affect engine performance. Reciprocating engines in particular will experience a significant loss of brake horsepower (BHP). Turbine engines are not affected as much by high humidity and will experience very little loss of thrust.

SECTION 8

TAKE-OFF PERFORMANCE

All conventional aircraft flights start at the point of departure with a take-off. In this phase, the aircraft is transferred from its stationary, ground-borne, state into a safe airborne state. Since the maneuver takes place in close proximity to the ground, and at low airspeed, there is relatively high risk to the safety of the aircraft. The maneuver must be carried out in a manner that will reduce the risk of an incident occurring to an acceptably low level of probability. In the conventional take-off maneuver, the aircraft is accelerated along the runway until it reaches a speed at which it can generate sufficient aerodynamic lift to overcome its weight It can then lift off the runway and start its climb. During the take-off, consideration is given to the need to ensure that the aircraft can be controlled safely and the distances required for the maneuvers do not exceed those available. In this section, we will discuss take-off performance terminology, which mainly includes the definitions of some distances and airspeeds, and the methods to calculate "V'' speeds and take-off power.

TAKE-OFF PERFORMANCE TERMINOLOGY The space available for take-off is limited by the dimensions of the runway and the area beyond the runway in the take-off direction. The runway is defined as a rectangular area of ground suitably prepared for an aircraft to take off or land. At the end of the runway, there may be a stopway or clearway.

Clearway- a plane beyond the end of a runway which does not contain obstructions and can be considered when calculating take-off performance of turbine-powered transport category airplanes. The first segment of the take-off of a turbine-powered airplane is considered complete when it reaches a height of 35 feet above the runway and has achieved V2 speed (take-off safety speed). Clearway may be used for the climb to "35 feet (see Figure 4-2). For turbine-powered airplanes, a clearway is an area beyond the end of the runway, centrally

64

located about the extended centerline and under the control of the airport authorities. Clearway distance may be used in the calculation of take-off distance. Stopway -an area designated for use in decelerating an aborted take-off. It cannot be used as a part of the take-off distance but can be considered as part of the accelerate-stop distance (see Figure 4-2 below).

Figure 4-l Take-off Runway Definitions

A stopway is an area beyond the take-off runway, not any less wide than the runway, centered upon the extended centerline of the runway, and able to support the airplane during an aborted take-off. Regulation requires that a transport category airplane's take-off weight be such that, if at any time during the take-off run the critical engine fails, the airplane can either be stopped on the runway and stopway remaining, or that it can safely continue the take-off. This means that a maximum take-off weight must be computed for each take-off. Factors that determine the maximum take-off weight for an airplane include runway length, wind, flap position, runway braking action, pressure altitude and temperature. In addition to the runway-limited take-off weight, each take-off requires a computation of a climb-limited take-off weight that will guarantee acceptable climb performance after take-off with an engine inoperative. The climb-limited take-off weight is determined by flap position, pressure altitude and temperature. When the runway-limited and climb-limited take-off weights are determined, they are compared to the maximum structural take-off weight. The lowest of the three weights is the limit that must be observed for the take-off. If the airplane's actt;al weight is at or below the lowest of the three limits, adequate take-off performance is ensured. If the actual weight is above any of the limits a take-off cannot be made until the weight is reduced or one or more limiting factors (runway, flap setting, etc.) is changed to raise the limiting weight After the maximum take-off weight is computed and it is determined that the airplane's actual weight is within the limits, then V1 (take-off decision speed), VR (rotation speed) and V2 are computed. These take-off speed limits are contained in performance charts and tables of the airplane flight manual, and are observed on the captain's airspeed indicator. By definition they Figure 4-3 Take-off Speeds are indicated airspeeds (see Figure 4-3). When the aircraft starts the take-off at rest on the runway, take-off thrust is set and the brakes 65

released. The excess thrust accelerates the aircraft along the runway and, initially, the directional control needed to maintain heading along the runway would be provided by the nose-wheel steering This is because the rudder cannot provide sufficient aerodynamic yawing moment to give directional control at very low airspeeds. As the airspeed increases the rudder will gain effectiveness and will take over directional control from the nose-wheel steering. However, should an engine fail during the take-off run the yawing moment produced by the asymmetric loss of thrust will have to be opposed by a yawing moment produced by the rudder. There will be an airspeed below which the rudder will not be capable of producing a yawing moment large enough to provide directional control without assistance from either brakes or nose-wheel steering or a reducing in thrust on another engine. This airspeed is known as the Min.imum Control Speed, Ground, VMcG· If an engine failure occurs before this airspeed is reached, the take-off run must be abandoned. During the ground run the nose wheel of the aircraft is held on the runway to keep the pitch attitude, and hence the angle of attack in the ground run, ag, is low. This will keep the lift produced by the wing to a small value so that the lift-dependent drag is minimized and the excess thrust available for acceleration is maximized. As the aircraft continues to accelerate, it will approach the lift-off speed, Vwy, at which it can generate enough lift to become airborne. Just before the lift-off speed is reached, the aircraft is rotated into a nose-up attitude equal to the lift-off angle of attack. The rotation speed, VR.. must allow time for the aircraft to rotate into the lift-off attitude before the lift-off airspeed and becomes airborne; this is the end of the ground run distance, S0 . The lift-off speed must allow a sufficient margin over the stalling speed to avoid an inadvertent stall, and a consequent loss of height This may be caused by turbulence in the atmosphere or any loss of airspeed during the maneuvering of the aircraft after the lift-off. The lift-off speed will usually be taken to be not less than 1.2 Vs 1, where Vs 1 is the stalling speed of the aircraft in the take-off configuration. This will give a lift coefficient at lift-off of about 0.7 Ctmax and provide an adequate margin of safety over the stall. If the aircraft is over-rotated to a greater angle of attack at the rotation speed then lift-off can occur too soon and the aircraft start the climb at too low an airspeed. This can occur if, for example, the elevator trim control is set incorrectly or turbulence produces an unexpected nose-up pitching moment. The minimum speed at which the aircraft can become airborne is known as the minimum unstuck speed, VMu· It occurs when extreme overrotation pitches the aircraft up to the geometry limited angle of attack with the tail of the aircraft in contact with the runway. Tests are usually required to measure the take-off performance in this condition. During the take-off run, should an engine fail between the minimum control speed (ground) and the rotation speed, the decision either to abandon or continue the take-off will have to be made. This decision is based on the distances required either to stop the aircraft or to continue to accelerate to the lift-off speed with one engine inoperative. There will be a point during the acceleration along the runway at which the distances required by the two options are equal. This point is recognized by the indicated speed of the aircraft and is known as the take-otT decision speed, V1• The decision speed also determines the minimum safe length of runway from which the aircraft can take off. If an engine fails before the decision speed is reached then the take-off is 66

abandoned, otherwise the take--off must be continued. Once the lift-off has been achieved the aircraft must be accelerated to the tak&-e>ff safety speed (V1). This is the airspeed at which both a safe climb gradient and directional control can be achieved in the case of an engine failure in the airborne state; this phase of the take-off path is known as the transition. The ability to maintain directional control in the climb is determined by the

Minimum Control Speed, Airborne, VMcA· The minimum control speed, airborne, will be greater than the minimum control speed, ground, VMcG, since the aircraft is not restrained in roll by the contact between the landing gear and the runway. In the event of an engine failure in the climb, the aircraft will depart in yaw, which will cause the aircraft to roll and enter a spiral dive if the yaw cannot be controlled. The take-off is complete when the Lowest part of the aircraft clears a screen height of 35ft above the extended take-off surface. The distance between the lift-off point and the point at which the screen height is cleared is known as the airborne distance, SA. The total take-off distance required will be the sum of the ground run distance, So, and the airborne distance, SA. To ensure that the take-off is performed safely, the take-off distances will be suitably factored to allow for statistical variation in the take-off performance of the individual aircraft and in the ambient conditions.

V1 (tak&-e>ff decision speed) is the speed during the take-off at which the airplane can experience a failure of the critical engine and the pilot can abort the take-off and come to a full safe stop on the runway and stopway remaining, or the pilot can continue the take-off safely. If an engine fails at a speed less than Vh the pilot must abort; if the failure occurs at a speed above VI> the pilot must continue the take-off. The take-off decision speed, VI> is the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot is assumed to have made a decision to continue or discontinue the take-off. V1 is also the speed at which the airplane can be rotated for take-off and shown to be adequate to safely continue the take-off, using normal piloting skill, when the critical engine is suddenly made inoperative. VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant but must not be less than 1.05 VMc or, at the option of the applicant, not less than VMcG· It is important to know that the critical engine failure speed is an obsolete term for V1 which is now called take-off decision speed. Va (rotation speed) is the lAS at which the aircraft is rotated to its take-off attitude with or without an engine failure. VR is at or just above V1• V1 (tak&-e>ff safety speed) ensures that the airplane can maintain an acceptable climb gradient with the critical engine inoperative.

VMv (minimum unstick speed) is the minimum speed at which the airplane may be flown off the runway without a tail strike. This speed is determined by manufacturer's tests and establishes minimum V1 and VR speeds. The flight crew does not normally compute the VMU speed separately. (see Figure 4-3).

V 1 is computed using the actual airplane gross weight, flap setting. pressure altitude and 67

temperature. Raising the pressure altitude, temperature or gross weight will all increase the computed V1 speed. Lowering any of those variables will lower the V1 speed. A wind will change the take-off distance. A headwind will decrease it and a tailwind will increase it While a headwind or tailwind component does affect the runway limited take-off weight, it usually has no direct effect on the computed V1 speed. The performance tables for a few airplanes include a small correction to V1 for very strong winds. For those airplanes, a headwind will increase V1 and a tailwind will decrease it A headwind, in effect, gives an airplane part of its airspeed prior to starting the take-off roll. This allows the airplane to reach its take-off speed after a shorter take-off roll than in no wind conditions. High rotation speeds and lower air density (high density altitude) both have the effect of increasing the take-off distance. A runway slope has the same effect on take-off performance as a wind. A runway that slopes uphill will increase the take-off distance for an airplane and a downslope will decrease it. A significant slope may require an adjustment in the V1 speed. An upslope will require an increase in V1 and a downslope will require a decrease. An uphill runway will have the effect of decreasing an airplane's rate of acceleration during the take-off roll thus causing it to reach its take-off speeds (V1 and VR) further down the runway than would otherwise be the case. An uphill runway will also necessitate an increased V1 speed in some airplanes.

If there is slush on the runway or if the antiskid system is inoperative, the stopping

performance of the airplane is degraded. This requires that any aborted take-off be started at a lower speed and with more runway and stopway remaining. This means that both the runway-limited weight and the V1 used for take-off be lower than normal.

CALCULATING "V" SPEEDS Although the method to calculate Boeing 737 "V'' speeds (including V1, VR and V2) is similar to Airbus 320 to some extent, it is still necessary to discuss the two methods respectively. Boeing 737 "V" Speeds

The table in Figure 4-4 is used in several problems to determine the pressure altitude from the indicated altitude and the local altimeter setting. The table uses the local altimeter setting to indicate the proper correction to field elevation. For example, assume the local altimeter setting is 29.36" Hg. Enter the table in the left-hand column labeled "QNH lN. HG", and then find the range of altimeter settings that contains 2936" Hg. Read the correction to elevation in the center column. In this case, add 500 feet to the field elevation to determine the pressure altitude. If the altimeter setting is given in millibars, enter the table in the right-hand column. Using operating conditions R-1 (see Figure 4-5), follow the steps for determining the "V'' speeds (see Figure 4-6). Enter the table at the top left in the row appropriate for the pressure altitude and go across until in a column containing a temperature range which includes the given value. In

68

r

ALTIME'"" • .;-; ....

I

STATiot~

J

TO PRESSURE

QFE

STATION

PRESSURE ONH tO PRESSURE! ALTITUDE

fo18S 1000 FT

700

CORRECTION TO eLEVATION

10 ONH IN. HG.

PRESS. ALT

FT

- 28.8- 1 8

28.91

- 29.02 7

29.12 29.23

800 8

29.34

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.\toO 1 HI • -1 0 -5 0 1000LB ~ 15 44 4-4 44 29 .1 .0 .6 156-156-156 156-156-156 156-156-155 4-4 9 4-4 28 31 4-4 .1 .1 .6 153-153-153 153-153·153 155-155-155 29 4-4 29 4-4 35 4-4 .5 3.9 .6 148-149-149 153-153-153 154-154-154 4-4 34 37 4-4 39 4-"1 .5 .2 .6 149-149-149 151·151-151 154-154-154 38 4-4 41 4-4 43 4-4 .7 .2 .4 148-148-,48 150-150-150 154-154-154 42 44 4-4 4-4 47 4·4 .8 1.1 .1 148-148-148 150-150-150 153-153-153 4-4 45 48 4-4 4-4 50 .e .7 .8 146·146-146 148-149-1 49 151-151-151 50 4-4 52 4-4 4-4 64 .3 .4 .s 148-146-148 148-148-148 149-149-149 !:>4 4-4 56 4-4 58 4-4 .:! .2 •1 145-145-145 146-146-145 147·147-147 58 4·4 59 4-4 4-4 GO .0 1.0 1.9 144-144-144 145-145-145 145-145-145 4-4 60 60 4-4 60 2.0 4.0 0 143-143-143 144-144-144 133-133-133 60 50 so .0 .0 .0 130-131-131 130-131-131 13C-131-i31 60 80 60 .0 .0 .0 12~12&-1:09 129-129-129 12~-129-129 80 60 so .c .0 .0 126-127-177 126·127·127 126-127-127

162.0 160.0 156.0

152.0 148.0 144.0

140.0

136.0

132.0 128.0

124.0

I

120.0 118.0 114.0

Figure 4-7

72

.... ......

RWY 15L JARA 20{02/S'i

I SEQ 002

ELEV. 489.FT CONF. TORA 9840.FT 1+F ASDA 9840.FT FWnc:c TOOA 10170.FT SLOPE .08 •;. TGA

10 31 4-"1 .2 156-156-156 4-4 33 .2 156-156-156 37 4-4

.2 156-156-155 41 4-4 .0 156-156-155 44 4-4 .!l 155-155-155 4-4 48 .4 153-153-153 4-4 51 1.1 151·151-151 55 4-4 .7 149-149-149 69 4-4 .2 147-147-147 4-4 60 3.1 146-146-146

60 .0 133-133-133 60 .0 130-131-131 50 .0 129· 129·129

6C

.o

126-127-127

Ta~ffRTOLW Charts

p 10

2

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s 4-4

37

.8 168-158-158 34 4-4 .8 158-158-158 4-4 38 .7 158-158·158 4-4 42

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48

155-155-155 4-4 49

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A. The maximum permissible take-off weight for the ambient pressure, temperature and surface wind conditions, or B. For a given aircraft weight, the maximum temperature at which a take-off would be permitted. This temperature (corrected for QNH and airbleeds) is called the flexible temperature. A specific chart is established for each runway. It is based on standard atmospheric pressure and takes account of the s~gnificant obstacles along the specified flight path. The configuration is indicated on top of the chart (see Figure 4-7) in the right comer. The weight corresponding to any box is the sum of entry weight and weight increment. It is the maximum permissible T/0 weight corresponding to the temperature shown in the box. The temperature shown in the box is the maximum temperature at which the maximum weight determined as above can be lifted. The limitation indicates the nature of the limitation or the balance between two limitations as resulting from the optimization. Limitation codes are as follows: A. Maximum structural weight; B. Second segment or first segment; C. Runway; D. Obstacle; E. Tire speed; F. Brake energy; G Take-off distance 2 engines operative; H. Final take-off.

In order to get the most out of the chart, there are two kinds of corrections: either on weight when determining maximum take-off weight or on maximum temperature when determining the flexible or limiting temperature. Any QNH variation from the standard, for which the chart is calculated, will affect either the maximum temperature or the weight. The air bleeds will affect the maximum temperature or the weight in the same manner. The effect of QNH variations or bleed consists of an addition or subtraction to the weight as specified on each chart.

Correction on Weight In order to avoid a loss in weight when the actual temperature does not appear in the chart, the weight gradients (Grad) on both sides of the flat rating temperature are given on top of the chart (Grad 1/Grad 2). Flat rating temperature is given, named Tref. Using the data, weight and temperature, given in the upper box of the column selected according to the wind, add the weight determined by multiplying the weight gradient by the difference of temperature between actual temperature and that given in the box. When these two temperatures (actual and maximum) are on each side of flat rating temperature, two steps are necessary. First multiply the weight gradient given above Tref by the

73

difference between maximum temperature and flat rating temperature. Then multiply the weight gradient given below Tref by the difference between flat rating temperature and actual temperature. Add these two values to the maximum weight of the first box. Note: Weight gradients must only be used to extrapolate above the maximum weight shown in the RTOLW chart (upper box of chart). They do not allow to interpolate between two boxes, neither between filled boxes, nor between one filled and one blank box. From this maximum weight, subtract or add the weight increment equivalent to the QNH variation from standard as indicated on the chart. Subtract bleed effect if any. The final weight is the maximum permissible TOW for the actual environmental conditions.

Corrections on Temperature QNH variations and bleeds affect the maximum temperature corresponding to a given weight. The resulting temperature called flexible temperature must be checked as shown on the chart in order to avoid: either a take-off at a higher weight than allowed by the maximum available level of thrust when the flexible temperature is lower than Tref or actual temperature, or setting a thrust derated by more than allowed, maximum derated thrust, i. g., maximum thrust at ISA + 46 "C for the actual conditions.

This maximum derating corresponds to a maximum flexible temperature of lSA +46 ·c. This fmal temperature called corrected temperature (CT) will be entered in the FMGS's MCDU. Any temperature below Tref should not be set. The maximum value of CT which may be set is ISA+46 ·c. Example

Refer to Figure 4-7 and Figure 4-8, find out the maximum take-off weight, the flexible temperature, and corresponding Vt. VR> V2 according to the conditions below. 1) Determination of maximum take-offweight.

DATA: OAT= 10°; QNH = 1 013 mb; 20 kt head wind; Air conditioning OFF; forward C.G. A. Enter in 20 kt head wind column and read temperature and weight: in first line at 32° 162 800 lb B. Use weight gradients for increase in weight capability: between 32° and TREF = 29°

2

between 32° and 10°

19 x 150

Total weight (Maximum capability)

x

600

1 200 lb 2 850 lb

166 850 lb

Maximum permissible take-off weight: for example 162 000 lb (depending on version) C. Read take-off parameters in 162 line for 20 kt bead wind config 1 + F: 74

VI= 158 kt VR= 158 kt

limitation: obstacle

V2=158kt 2) Determination of flexible temperature. DATA: OAT = 15°; Take-off weight: 144 000 lb; QNH= 1013mb; No wind; Air conditioning OFF; forwardC.G A. Enter with 144 000 lb and no wind and read temperature:

47 'C

B. Check the temperature that is lower than maximum flexible temperature: Flex temperature to be enter the FMGS's MCDU

47

·c

C. Read take-off parameters in 144 000 lb line for no wind:

Vi= 153 kt VR= 153 kt

v2 = 153 kt ~A3~0 orr .....

, ..KJttt Qrt'W

tnt~.; MNct.~AL.

\

TAKE..OFF

2.02.30

RTOLW CHARTS

REV 13

p9

ISEQ 032

EFFECT Of O.NH AND I OR BLEEDS

I

!

to :oh ~r.to atn poul>lc

Dt'-rmno MAX TOW

• When eirport pressure altitude becomes negative : - ~ geometrical eltnude is negative or equal to 0 : subtract 30 lblmb - if geo:netrical eltitude is positive : add 40 lb/mb down to 0 h pressure altJwde, then subtract 30 lo per additionoi mb.

Figure 4-8 Effect of QNH and/or Bleeds

75

CALCULATING TAKE-OFF POWER Engine Pressure Ratio (EPR) is the thrust indication used on many turbojet aircraft. Basically it is the ratio of the engine exhaust pressure to the intake pressure. For example, if the exhaust pressure is exactly twice the intake pressure, the EPR is 2.00. The EPR setting for maximum take-off thrust will vary with altitude and temperature. In addition, reductions in EPR have to be made when bleed air from the compressor section is used for air conditioning, engine anti-ice and internal regulation of the engine. Boeing 737 Take-off EPR

The table at the top of Figure 4-6 is used to determine take-off EPR. Enter the table with temperature and pressure altitude. To determine pressure altitude, use Figure 4-4. In the table of Figure 4-6, two EPR values are found: one for temperature and one for altitude (be sure to use the table in Figure 4-4 to determine the pressure altitude). The lower of the two is the take-off EPR. For example, if the temperature is 50°F at a pressure altitude of 500 feet, the temperature-limited EPR is 2.04 and the altitude-limited EPR is 2.035. Since there is no listing for this altitude in the table in Figure 4-6, it is necessary to interpolate. At sea level, the altitude-limited EPR is 2.0 l. At 1 000 feet the corresponding value is 2.06. Since the pressure altitude in this case is exactly halfway between 0 and 1 000, the EPR setting should be halfway between as well. The only possible correction would be for if the air conditioning bleeds are off. Using the data from Operating Conditions R-4 (Figure 4-5), the field elevation is 2 000 feet and the altitude correction is - 100 feet (refer to Figure 4-4), which results in a pressure altitude of 1 900 feet. Since there is no listing for this altitude in the table in Figure 4-6, it is necessary to interpolate. Since the altitude given (1 900 feet) is not halfway between the two table values (1 000 and 2 000 feet), it is necessary to calculate the amount the EPR changes per 1 000 feet of altitude. Determine the difference between the EPR values at these two altitudes (2.11 - 2.06 = 0.05). That means the EPR variation from 1 000 feet to 2 000 feet is 0.05. The EPR variation per 1 000 feet is 0.005 (0.05/10), and the EPR decreases as altitude decreases. To determine the EPR for 1 900 feet, subtract 0.005 from the EPR for 2 000 feet (2.11 0.005 = 2.1 05). The temperature-limited EPR is 2.11. So the take-off EPR for operating conditions R-4 is 2.105. Airbus 320 Take-off EPR

The table at Figure 4-9 is used to determine take-offEPR. Enter the table with temperature and pressure altitude. Each intersection of temperature and airport altitude has a box with one take-off EPR The note for EPR adjustment is located on the top of the table. For example, with an OAT of 28 ·c, an airport altitude of 2 000 feet will result in an EPR value of 1.419. Ifthe temperature and altitude value does not appear in the table, the interpolation is necessary. For example, if the temperature is 27 ·c at a pressure altitude of 1 500 feet, the EPR is 1.418. Since there is no listing for these temperature and altitude in the table in Figure 4-9, it is 76

~A320

IN FUGHT PERFOMANC£

3.05.06

THRUST RATINGS

REV 17

FUG>fT CREW OPfRATING MANUAL

p4

l

SEQ 030

TAKE-OFF EPR

TAKE-OFF EPR

V2SOOA1

EPR I:ORRECltlHS FOR AIR BLEED

-.010

-.010

lfm.r.:£ It(

Q.OOO

-.017

HACfU.E

l>~ll-U

-.007

-.024

AXD

lflo ~11-JCf Cll

ALTITUDE -1000. !. 31S 1.375

!.3W

1. 412

1. 428

i. 4'3

1.458

\.39:'

1.~

1~.0

1.3i'S

!.3'.17 1. 3'.17 1.3'.17

1. «3 1. «3

1.~

1.315 1.375

1. ~12 1.4l2

16.0 18.0 20.0 22.0

1. 3('5

2~.0

1. &75

1. 397 1.397

26.0 2B. 0 30.0 32.0

i.37S

3~. 0

28.0 ~0.0

~2.0 ~4. 0 ~6. 0

.."' 0

0

u

1.509

1.~

1.~

1.49l,

1.~

1.509 1.509

1.474

1.~

1.4'>4

1.~

1.484

1.4'>4

1.~

1.509 1.504

1.(28 1.1:26

1. 11a

1. ISS

, • .W4

1.~

1.4~

1.4~

1.494

1.4~

~.

1. 1, 1.357

:.303

1.303

;.373

1.338

\.338

'\.344

1.~9

l.3S~

1.300

1.304

1.330 1.323

1.33&

1.~1

~.a;o

1.3~5

1.329 1.321

~ 1.343

1.356

1.~

00.0

0

56.0 58.0

1.~

1-'"

0

o·

J, IS-4 1.~

1. 450

52.0 54.0

0

1.~4

1. -'84 1.4$

1.458

1. 315 1.308 l.al)1

0

4511

"''

\,«3

46.0

0

i.

\.

'!.443

. • .....

so.o

1.4211 1.4211

1.1,"

1.~

1.330 1.322

~ 0

(FT)

0. 1000. 2000. 3000. 4000. 5000. 6000. 7000. 6000. 8500.

-00.0 8.0 10.0 12.0

3&.0

0 ....

OAT>lO ICI

~"l!.E

(Cl

« <

OAT~IU

J,l&t•,u 1

24•••l • ~;·•1(}{ t&U.'.YJ' ·t;:;~:~

7:i.T:I7~C I ~11l