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Instrumentation

The document provides detailed notes on the Pitot static system, which measures airspeed, altitude, and vertical speed in aircraft. It explains concepts such as static pressure, dynamic pressure, total air temperature, and various errors associated with airspeed indicators. Additionally, it covers calibration formulas, the effects of compressibility, and the importance of accurate temperature measurement for flight performance.

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88 views76 pages

Instrumentation

The document provides detailed notes on the Pitot static system, which measures airspeed, altitude, and vertical speed in aircraft. It explains concepts such as static pressure, dynamic pressure, total air temperature, and various errors associated with airspeed indicators. Additionally, it covers calibration formulas, the effects of compressibility, and the importance of accurate temperature measurement for flight performance.

Uploaded by

singhxyz495
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CAPT. SAHIL KHURANA (91) 9971663490, (91) 9871866290 4 INSTRUMENT NAVIGATION I | 07a 8722620 aN ANAM alo f, Nalial) y a (ADD aliaf inlin fa nO inna a CAAA ACEC EACGROSECR OREO ER GRE DEAE; Worurir or ee ibeabs : sie Bry ie ied with CamScanner Scan Z Dy - \ PITOTSTATIC SYSTEM NOTES-DGCA Alot Ts" | | The Pitot St jie both the PitoY’and St&tic pressure for the —) Airspeed indjcator{ASi), The Altimeter and Vertical Speed Indicator(VS!) And” MACHMETER : { O Ambient pressure is known as STATIC PRESSURE. O Static Pressure acts on all parts of the aircraft, from all direction. Static” » Pressure is present at all times, whether the aircraft is stationary all the ground, or in flight oh ~ hued toute fe Dywournio Ie = = 4 the airspeed indicator measures the dynamic Pressure; thatisthe | difference between Pitot and Static Pressure a Ps a 7 w Oe Ris due to turbulent airflow in the region of the be it La phoitet Prove pitot/Static head . (lose ows ts Usinys Prod & te P! as “y plod outriole, 6 O About 4% of the combined pressure head position error is eliminated eg eg by the use of a separate STATIC VENT; |// whaiose) ACOMBINED PITOT STATIC TUBE ~ AIR TEMPERATURE MEASUREMENT ent of air temperature is of importance to a pilot, not just to The medsurem f imp lish the lif ‘engine or airframe icing, but also in connection with X any other ospects of leaf neformance Ss cr THE EFFECT OF COMPRESSIBILITY rature outside the aircraft appears a simple The measurement of air temper tudes into the air stream should apparently be task, a thermometer which protr sufficient to do the job. However this is not the case, because.0s oircraft speed ‘SAHIL KHURANA SEC: 7, DWARKA,ND-75 09871866290 Ak kk ke ek ek td See Saag ee eee 3 hk ww ao po ai yg Scanned with CamScanner 8 eS —ti‘i‘ : cxeved Y | po gk OO atin, cause O} o A? increases, the air close up to the aircraft becomes compressed, and because of this compression that air is heated. ; ive This means that the temperature sensed will too warm and not representative of the actual air temperature. (Sranic are Temperature sar) /QAT fr temperature of the ena, ‘ait through which the aircroft is about to fly. TOA Y TOTAL AIR TEMPERATURE (TAT) is the maximum temperature attainable by the oir weg? brought to rest, adiabatically. - Y a The increose of air temperature at higher speeds os 0 result of compression afd the effects ihe oes oS et ee of friction is known as the ‘RAM RISE. The percentage of the ‘ram rise’ (RAT) sensed and recovered by a TAT. piobe is termed the Recovery Factor (k). Recowy The 1) SAT = Vistietuebispeedin knots sar ap static Air Temperature Brasairexmnre RusVIM osteo (enw GoompaessehMly Oousiy ‘RIRSPEEDS, TAS{indicated Air Speed) “CaSiCalibrated Air Saeed) TAS = CAS + (1.75% of CAS per 1,000 ft of atitude)) . ros BL LP DC sree ur ctt0n Conon nes (™OMLYAPOLLLALy CLLOA ) * POSITION OR PRESSURE ERROR ~ Arises as the A/C movement through air causes a disturbance which CAS 2 compressibility corrections III UU 00 OU SO OF FFE HIE PE OH Wg Q®aOo Jeuvre-Induced Errors - These are associated chiefly with manoeuvres involving change in angle of tan. attack, giving transient errors and a lag in the indication of changes in airspeed. Size of error depends upon SAHIL KHURANA, ‘SEC- 7, DWARKA,ND-75 09871866290 Ww Fe ~~ U -U-Y -U PU Ut ww a Scanned with CamScanner POLL WPUSUPOPUIUPUPU"UPEP LP UPL URL IP OP USEF pow eke: dus do \J enh Gortralin. See 2 OOH Weld mM + Angle of Attack of A/c tobe vd we enfowg ‘ A. COMPHESSIONITYENROR © AUIAS> 300 knots + At Altitude loss dense aii easily compressed than + denser aie at Sea Level resulting n greater dynarnlc + qusssstroovenmn Wf" oO wy + CL increases dnectly with both Arapeed & Altitude 7 wr 44 DENSITY ERROR -untess te round the wero 1.0 the catrton deny of 1.295 ba per eb metre, which eon only occur nor se lve the AS! anno cnc nie FX summeorisina, nN a {DENSITY ERROR’. aca) ne ¢ fbctow MSL the ASI wilaver read the tue speed. \7"7 Ks f£ Dons Eptoer SS Tor TAS SUMMARY OF ERRORS CAS = IAS + PEC + IEC EAS = RAS + CEC TAS = EAS + DEC SAHILKHURANA SEC- 7, DWARKA,ND-75 09871866290 ss Scanned with CamScanner BLOACKAGEs _ doer 1 pror If blocked, ASI will not react to. anges eu a8 ‘gies to changes of Arspe iowever the capsule wl at Srometer préducing an indication of INCREASE OF SPEED IF THE A/C CLIMBS & A DECREASE IN SPEED IF ALC DESCENDS —: 2 stanic W{blocked, the AS! will over read lower Altitudes (Dangerous) Kwill under read when climbing at higher altitudes LEAKS ? 2 ypsuused Ow aa rnor-sestarteussss bmi fo palic Loss sus Quartead STATIC In unpressurised A/C AS wean | “rach Bg Unprerutiatd A/c) In pressurized A/C- S| under reads (Outside air arses higher than static) RARE POPP 6 620969 CIC 9@, OVER READING of AS! is Dangerous - A/C will stall at highenindicated airspeed PPK PUP NY V-SPEEDS = Vag (RED UNE), ey Mer ] 2. Vo Normal Ops (clean) AY Ie 3. Vsl~stolling speed (cleon) > a , % 4. _yeo=S5 en ae fom fred 12 hide . Me wire ae 6 2 cnceuane . ne r z ~ c v~ ASL COLOUR CODING ‘SS WHITE ARC VSO to VEE (SS with flaps & gears fully fully extended to max a speed with flops extended) (Fg footy, > GoFE > > GREEN ARC VS1 to VNO (SS Clean. aire) ) 62 e@LMo > YELLOWARC wore wne(Couborary ford tory Y 7 NOME > REDRADIALUNE —_VNE & Sy BLUERADIALLINE _VYSE Best single engine climb speed in a twin engine aircroft. SAHIL KHURANA ‘SEC- 7, DWARKA,ND-75 09871866290 IPM Cy Kye $i, Scanned with CamScanner mo > RED AND WHITE Indicates CAS value of VMO STRIPED POINTER at low altitude and MMO at (BARBERS’ POLE) high altitude. Nee oe eee ee eee ee) TAS = (AS + (1.75% of CAS per 1,000 ft of Altitude). > £9: J0r 0 CAS of 100 kt at 10,000 ft: TAS = CAS # (1.75 x 100 x 10) = 117.5k oy SY STATIC BALANCING A oy DAF wisest fort we paced oath sds of usage hiss calle STAC BAUIMCING. Static balancing helps reducing postion error when A/C Side sippin inate S te ‘Whenever A/C side Slips the port onthe other side helps Daan hes fig era mune sensed on one side cca IC side slippin Sesser kg ANS : OVER READ 2. A/Cside slipping towards the open port a other side is blocked 7 ee ‘ANS: UNDERREAD XY ee a ciate Sil ey oe + desl Mls tet ecttaet fee 09871866290 Ur UT ee err Ceerwns Tre me UU ere wee ww ww ee ne sss lib, Scanned with CamScanner 1. Apitot head is used to measure: a) dynamic minus static pressure. b) static plus dynamic pressure. c) static pressure. d) dynamic pressure. 2. A static vent is used to measure: a) dynamic pressure minus pitot excess. ( b) dynamic pressure plus pitot excess. . c) atmospheric pressure.» d) pitot excess pressure ~ Prot (mated Ake) ( head ds. A pressure head is subject to the following errors: Paeurl 7 a) position, manoeuvre induced, temperature. the flet b) position, manoeuvre induced. : Ce ¢) position, manoeuvre induced, density. « d) position, manoeuvre induced, instrumént-« 4. Turbulent flow around a pressure head will cause: a) density error. . b) 95% increase in manoeuvre induced error. c) an increase in the dynamic pressure. d) 95% of pressure eror.# . i Skvranoeuvre induced error: a) is caused-by pressure changes at static vents and lag.« b) is likely to, Be greatest when yawing after engine failure. c) is combined with instrument and position error on a correction card. e d) la$ts-for only a short time at high altitude. 6, Position error: ; Q ) may be reduced by the fitting of static vents.° b) will usually decrease with an increase in altitude. S he attitude of the aircraft. aircraft approaches the speed of sound. c) will depend solely ont d) will usually decrease as the e following instruments: QV $09 90 99 FD BIT DD I FU FIFIFUFIFU FY Y HE TELS IG Mo Ss h 7. Pressure heads supply data to th “ SAHIL KHURANA SEC: 7, DWARKA,ND-75 (09871866290 bs Scanned with CamScanner a) air data computers, altimeters, ASI's. - cealuusels b) standby instruments only, when air data computers fitted. WJ oats O~ ¢) altimeters, ASI's, VSI's, machmeters, air data computers. * - d) all the abi i S adeaiathite fe above plus air driven gyros. 8. Static vents are usually fitted to both sides of the aircraft fuselage. This will: \ a) reduce the position error plas b) balance out errors caused by side slipping or yawing.» Sodic B © Doing F C) require a calibration card for each static vent. ° ~ y Aes d) enable a greater number of instruments tobe fitted. fn Low i) 9. Which of the following instruments require inputs of both mgr pressure: y a) airspeed indicator, machmeter and vertical speed indicator, ° b) airspeed indicator, vertical speed indicator, altimetey ¢) airspeed indicator only. d) airspeed indicator and machmeter.» 10. Where an alternate static source is fitted, Use of this source usually leads to: Py ——e_" ™ —_— a) a temporary increase in lagerror. b) a lower pressure error than with, Arma sources c) an increase in position error.e———> €) no change in position errort> GE SAHIL KHURANA SEC- 7, DWARKA,ND-75 09871866290 ‘Scanned with CamScanner ce ‘AIR TEMPERATURE MEASUREMENT y ol 1. Converted into degrees celsius soy a) -56.5°C oce b)-40°C - ¢)-20°C ~ ho ce d) -108°C aS &> 2. In an aircraft thermometer with an electrical resistance sensor to meaty the air temperature, the resistance wire element is probably: -~ a) plutonium © b) platinum. ©) potassium - d) beryllium copper or TAT 3. Flying at high speed at high altitude, the differefite,bétween ram air temperature and static air temperature is: aV Slow. a) likely to be less than when flying low and 3 b) due to adiabatic cooling. “ c) due to adiabatic warming. e 4) proportional to the square of the dBZblute temperature. 4. Aircraft air temperature theGmoimeters are shielded to protect them from: Qe a) radiation.» RS b) accidental physical damipge on the ground or hailstones in flight. c) airframe icing. <>, d) kinetic heatig, is 5.Ata tryegigteed of 500 knots, a ram tise of airtemperature canbe 5 expected of ey . a) SO-deprees Celsius VU ; Koo nips Beers Cera ACE [00 c) Sdegrees Celsius \ Xa) 16 degrees Celsius 6. Anair temperature probe may be aspirated in order to: a) prevent icing. . air temperature on the ground. « ree wa b) measure c) compensate for thermal soaking at the ramp position. d) reduce the effect of solar radiation. SAHIL KHURANA SEC- 7, DWARKA,ND-75 09871866290 Scanned with CamScanner 7. Total Air Temperature is: a) the maximum temperature a! adiabatically. « b) the temperature indicated on tl ttainable by the air when brought to rest, he air temperature thermometer plus the ram rise. c) the static air temperature minus the recovery factor. NS d) the recovery factor plus the ram rise. & out Cut — ae” 8. The difference between static air temperature and total air temperature }: known as: a) corrected outside air temperature. © b) the ram rise.e Ww c) the recovery factor. - d) hot ramp radiation. oO pda direct reading aircraft thermometer usually cohsists of a bimetallic helix protruding into the airstream. Movement oon over the temperature scale will depend upon: a) difference in electrical resistance of the two metals. b) increase in pressure as airspeed increa: ‘e c) increase in adiabatic cooling as airipeed increases. d) different coefficients of expangion Of the two metals. to indicate changes in of remote reading ther@ameter depends upon temperature: a a) change of electricabresistance of the two metals. b) change of electrical resistance with temperature. c) change of electeical resistance with change in pressure. d) change ofelectrical capacitance with change in temperature. 4, eg DO s | « | 7 ee B BofA B | D B SAHIL KHURANA Scanned with CamScanner 8 a 3 S a | > 5 5 5 5 > ) ) ) ) ) ) : om . fasz 2 AIRSPEED INDICATORS 1. If the pitot line to an ASI becomes totally blocked during a climb, the AS! reading will: a) decrease, no matter what the actual airspeed is. v on bi , ef 0 increase, no matter what the actual airspeed is.+ ) progressively under indicate the value of the airspeed. Alte d) stick at the airspeed showing at the moment of blockage. GS ) 2. Compressibility error: a) causes overreading of the ASI at all levels whenever TAS exceeds, 20D kt: b) causes overreading of the ASI whenever CAS exceeds 300 kt. c) is calibrated out of the ASI at MSLISA conditions and only caiises overreading when air density is decreased and CAS exceeds 3Q0 kt. 4) is calibrated out of the ASI at MSL ISA conditions anq-only,causes overreading when air density is decreased and T AS exceeds 300 kt.» 3. If the static line to the ASI becomes blocked dring a long descent, a dangerous situation could arise due to the ASI, a) overreading, this indicated speed falsely showing the aircraft to be further from the stalling speed than it actually is. ~ b) underreading this indicated spged falsely showing the aircraft to be closer to the stalling speed than it actuay c) underreading, this indicated'sppéd possibly leading to the operation of flaps and/or landing gear at speés,in excess of safety speeds. d) overreading, this indicated speed possibly leading to the operation of flaps and/or landing gea atspeeds in excess of safety speeds. 4, An aircraft maifitaining a constant CAS and altitude is flying from a cold L—? 7 airmass intovygrmer air. The effect of the change of temperature on the speed wilf.pe: ars a) CAS will eee Dy = CAS= vs c} TAS will increase. » TAS DIAS Xd) TAS will decrease. 5. The airspeed indicator is calibrated to: a) conditions of the International Standard Atmosphere. b) conditions of the International Standard Atmosphere at MSL. + c) an air density of 1013.25 gms/m3 : d) indicate correctly in any atmosphere. SAHIL KHURANA SEC- 7, DWARKA,ND-75 Scanned with CamScanner a “of ” 6, Dynamic pressure is equal to: Ore t ayn? t b)¥eves °) eae \ U . d)M.GH uf al iP oc ay a 7. Excluding blockages, the full list of errors of the astis: DVL 7 OF a) instrument error, position error, density error, manoeuvre induced apt) ) b) instrument error, position error, temperature error, compressibility eFror Manoeuvre induced error. ¢) instrument error, position error, barometric error, temperature\errs , lag, manoeuvre induced error. d) instrument error, position error, density error, compressibility error, manoeuvre induced error.» cy ry ad 8. Some ASI have coloured arcs and lines markedn their dials. A yellow arc 77 and a white-arc indicate: 4 wv a) cautionary range and normal operating range, b) flap operating speed range and normal operating range. c) cautionary range and flap operating speed range. 4d) flap operating speed range and calftionary range. SER SSS ESSER Eee eY ss, < Cncx 9. What will be the TAS if cruising altitude is 39 000 ft, temperature is ISA +5 and CAS 200 kt: a a) 388 kt \S CAS~ ook (x3 ) 380Kt ww PLT - 34,000FT ic) 364 kt aL OA - \SAtS d) 370 kt y 10. wags line to the ASI becomes blocked during a climb, the ASI readjqg will: increase, no matter what the actual airspeed is. 4 eresively under indicate the value of airspeed.* Xo) progressively over indicate the value of airspeed. {stick at the airspeed showing at the moment of blockage. SIS U9 CU OU YOY BU EL OY RO OO 2 3 4 5 6 7 8 9 10 B D A Cc B B D c B B AWD GQ bs SAHIL KHURANA Scanned with CamScanner (consraucnon = sinip(e RLTIMETER — ole ei Altimeter 1 io Indication sorting Window aneroia SORT bd Seale Waters 1 0.000, Ee 100 ft Pointer Leaf fH" animeter sorting | ESS. Adjustment Knob /\ alg when dleplayin: Sulsacalar eg deptaring ellis kyrvglg Fo.800 eet Fist” PRESSURE ALTIMETER ae + Indicates height above a selected prestore.datum Cv ie, Qua, QNE PRINCIPLE v . Av vi . Stic ic pressure decreases th bight [ress Roveotes with 3 xia tee «The Pressure Altimetet is a sensitive pressure Gauge calibrated to indicate height above a selected datuiy level (mets 2) evacuated and sealed PRESSURE ALTIMETER consists of thin metal capsule which is . erred fom collapsing by means of a LEAF SPRING Yeonsists ‘of a single capsule mounted in AIR TIGHT CASE 2) Case is fed with static pressure from A/C static tube or vent wing the copsule to expand As the aircraft climbs the pressure in the case falls allo ee Conversely, decrease in Height compresses the copsule © The linear movement Is magnified and transmitted to a pointer SAHIL KHURANA SEC- 7, DWARKA,ND-75 09871866290 Scanned with CamScanner 15 i is provides to drive Q@ SENSITIVE ALTIMETER (Altimeles umber: 2) Ol The sensitive altimeter employs a minim for amore accurate measurement of pressure and provides m: y ? ; B the mechanical linkage. 2 O Within the mechanical linkage, a bi-metollic insert is fitted to compensate for 4 ? \ ; ; ? temperature changes that could affect the movement Qseavoassisren aurmeren (AUlmelr runler-3) C +f 60 FL S + In this instead of mechanical amplification, the copsule assembly is made partof” SERVO SYSTEM resulting in greater a = ° ‘ U, KI * LAG ERROR is virtually eliminated in SERVO ASSISTED ALi bw, Lhe A, ERRORS IN PRESSURE ALTIMETER “es Y 3 1. INSTRUMENT ERROR ~ Due to manufacturing sete, 2 Kh. LAG ERROR (time lag) ~ Since the response of the gale or linkage is not instantaneous, 3 ‘The altimeter needle lags whenever height is inéreased or decreased rapidly, causing a under read on climb and adondescent \ Lag error is virtually eliminated in Servo.Astisted Altimeter // —_ 3. POSITION ERROR (PE) - Due to incorrect static pressure created in the vicinity of static vent due to disturbance of airflow ofer it. ; S ? 4, PRESSURE ERROR (aoxsnsdie Pressure) — Occurs wi ial datum pressure differs fal rected by.corcect settis Yy Ks. rempenarune GOR ~ Altimeter calibrated on ISA + 15°C and lapse rate of 1.98°/ 1000. uSyally differs, so the en .témperature difference of 10°C from standard results in an error 0 wor pophimately 6 ofthe naeoed aude, \o=eny, Lat afertitiuben, ollie . . , p -\ivsTERISIS ERROR (clue Ae Line Josdl. p ] ) , reading during aclimb or descent. within the instrument case will remain conston(S ead | 6. BLOCKAGE - «= _Ifstatic vent is blocked the pressure. + “Altimeter will continue to register height indicated when blockage occurred ‘SAHIL KHURANA SEC- 7, DWARKA,ND-75 09871866290 : Scanned with CamScanner 16 * Break glass of VSI or Mach meter to get Altitude/Height 7. LEAKAGES 1. LEAK INA STATIC TUBE (pipe) — With in a pressurized cabin allows increased static pressure to enter static lines. This causes the altimeter to jadicate Cabin atid (Umelex Atedl ) 2. Within a Non Pressurized A/C- static pressure inside is slightly less than local \ n atmospheric static pressure. So a leaking static ec state lines this couses altimeter to over indicate slight (overrcacl) Y IMPORTANT FACTS Abo bi Moss F 1. Altimeter under indicates (under reads) when Actual Temp > ISA or when femp increases —— cece) 2. Altimeter over indicates (over reads)when Temp » An altimeter with barometric subscale set to oto wits reads 1500 feet if subscale is reset to 1006 mbs the alt will read? 1290 ft 1300 ft 1710 ft* Nv Pe : Sy] 3. iy ‘on ground. Next morning when QNH 1002 mbs what wi > . ; : > ‘ read. What will altimeter read when set to curre xe & | “read. What willa a nt Okg? Zeng F ¥ : 5 5 ; ; ; ? } , : y 4. Ana/caltimeter setting 1013mbs lands at an aefodrome [elev 300 ft] with QNH 1026 mbs. What will altimeter réad on landing. 4 \* ae . An a/c takes off from A elev 300 ft on QNH 1010 mbs and lands back after 4 hrs when altimeter reads 390 ft on ground. What is current QNH and QFE? ax ~ 6. Ana/c on FL 70 overflies at elevation 7000 ft when local MSL pressure is 1023 mbs, Willthe a/c clear the hill if so by what margin? lal AN |. An a/c leaves point A QNH 1000 MBs, ELEV 210 FT for aerodrome B ‘eJev 300 ft. There is a hill midway with highest QFE 1000 mas) 7 4 5000 ft amsl. Ifa/c leaves A with altimeter reading 270 ft+ a elevatio! a. What,minimum indicated altimeter reading should a/c fly on QNH of A toglegt fhe highest hill by 1500 ft. OL y quid wld ALCL /c takes off from A [elev 600 ft] aerodrome pressure 1008 mbs. . Xie altimeter on QNH reads 630 ft on ground and has to clear a 7210 ft high hill midway by a margin of 1500 ft before landing at 8 [elev 330 ft] x QFE = 1005 mbs. If a/c maintain QNH of A throughout, find S a. Minaltimeter reading to clear the hill b. Ac altimeter reading on landing at B c. What will be the vertical separation of another a/c without any strument error which overflies the hill at FL 90 Scanned with CamScanner 9, An altimeter reads 7000 ft on 30.42. what is P.A a. 7500 b. 6500 c. 7009 10. if an aerodrome elevation is 600 ft and PA 660 ft. What is QNH and QFE. a. 1015hpa/995hpa . 1011hpa/1031hpa . 1011hpa/991hpa . 1015/1035 hpa Goa fe . 2200 aos 1. 2. 1710" 3. 960’ zero 4. - 90° 5. 1007 hpa, 997 hpa 6. Yes, 292.5 ft 7. 6410 ft. 8. (a) 8920 ft. (b) 690 ft (c) aco Scanned with CamScanner 2 Se Oy gan Pa Vowape PON pales pnnune HIGH SPEED FLIGHT (MACHMETER) i it, Asan In High speed ait " vs aircraft approaches the local speed of sound the airflaw over some parts of to the speed of sound and a Ty 4 y the fuselage or wings may be accelerated shock wave will form. ¢ The speed at which airflow over some part of the. AS speed of sound, and G Na uz mber, known as - Mcrit Kv shock waves form, is called the critical Nich | Mochnokert O Is essentially a Pressure Altimeter and an ASI combined in to one N b+? ees J (ret 9) instrument . * O Itindicates Aircraft Spel relative to LSS (local speed of sound ) ss)” ‘important at high altitude since the speed of sound D ALT wu ane first reaches the O This is ic loach decreases With’ temperature and temperature decreases with altitude. Hence greater the altitude lower the LSS. The two capsules and linkages to indicate the aircrafts True USS 8 ‘Air Speed (TAS) os a proporti LSS] y" 4 jp iacmsnnsmincmnmnscteses (Qt of changes ia-the Dynami ENE rhe second capsule is 0. ied ater Sn AE contact. 's the static pressure inside the instrument case changes. c 2 |S Mach mo 7 LSS SAHILKHURANA ‘SEC- 7, DWARKA,ND-75 09871866290 Scanned with CamScanner SN Pre wea uo NozASE — Vale — Ft >_ 148 AULT Stte Ss coe Sap STATIC AUTIT ADJUSTABLE CRITICAL] PRESSURE ULE MAIN sHarT CAPSULE MACH NUMBER INDEX itor PRESSURE AIR SPEED CAPSULE SPEED OF SOUND nero erature) A formula for calculating the local speed of sound, 7S) is: where, pee ae tet ct ¢ tar AOC = aes? ss. ie LSS = 38.! savin> Lada Tis the absolute temperoture) 2 °C = 273° K) In ISA conditions at mean sk feve (+ 15°C) the speed of sound is ik, 8 ae while 36 und will have reduced to 573 knots. < . (P=S = Dynamic Pressure — ASL s Static Pressure ALT. INSTRUMENT ERRORS ae Sabu instruments, machmeter i ring tolerances, A eae PRESSURE ERRORS / Potion. OMOA These errors are small at the altitude machmeter are used. aac SAHIL KHURANA SEC- 7. DWARKA,ND-75 ‘Scanned with CamScanner oy Za 3. DENSITY, TEMPERATURE, AND COMPRESSIBILITY ERRORS OAL The: ik ier the’ s€ errors are eliminated because density changes do not alter the dynamic pressure/static pressure ratio. « MNO = Ase) BLOCKAGES ALT BD Mote STATIC SOURCE BLOCKED - INA CLIMB Machmeter will therefore under read. Ifa blockage occurs IN A DESCENT The Machmeter will therefore over read. Ss PITOT SOURCE BLOCKED ~ yy The Machmeter will over read in the climb and under read in the descent. Pa Machmeter Blockage errors are the same as the ASI Blockawe Errors. DY g co *_ Machmeter are calibrated to a formula relating Macinumber to atmospheric conditions of pressure and density. This is the only instrument not calibratedfoulSA and don’t have anything called “A DENSITY, COMPRESSIBILITY, TEMRERATURE ERROR N ACCURACY. +.01M_—> inch Quamboang Qu 8 Speedo} sound 661 knots at Sea Level and ee se 573.8 knots at 36090’ in ISA. Sif the pressure altitude is 18 000 ft, cxample Kaosss then the TAS is: X JAS of 220 knots , o® SPO G90 SU SOLO U FU PU VESEUETEUE OLR er 6 the COAT is -30°C and CAS is 170 RIWLIS ISD HI SBCISII “DU ~~ Scanned with CamScanner 6 wee 6 1. Determine the TAS corresponding to 0.70 M at JSA MSL (+ 15°C or 288°K). 2. Calculate the altitude in the atmosphere at which a TAS of 450 knots corresponds to Mach .80 —z- 3. If a decrease of 0.12 in the Mach Number results in a decrease o0f80 Knots 4 in the T AS, what is the local speed of sound . . 1 4. An aircraft is flying at FL360 with a TAS of 467 Knots at Mach No 0.8 wh the temperature difference from JSA is +9. What is the Temperature . difference at FL320 if Mach 0.8 still gives a TAS of 467 Knots. { \ MACHMETERS 1. The local speed of sound is equal to: A (K= Constant) : AW a) Kv temperature (°F) knots een e b) KV temperature (°K) knots » \wS c) KV temperature (°C) knots - me d) Kv temperature (°K) metres per second, * . ww Hf. At FL 350 with iy 7 #15, the ti d when flying at M ; with a JSA deviatior’of “12, the true airspeed when flying a ALT . 0.78 is: a) 460 kt AW b) 436 kt « x c) 447 kt A d) 490 kt aL.” 6 4a © ay” Bs. vivercienbing a a constant mach number below the tropopause through c% YY a) the CAS and TAS will both increase. Xp) the CAS and TAS will both decrease. Q c) the CAS will decrease and the TAS will increase.+ d) the CAS will increase and the TAS will decrease. 5. When descending below the tropopause under normal conditions \g temperature) at a constant CAS: (increasin a) both TAS and mach number will decrease.+ SSAMIL KHURANA SEC- 7, DWARKA,ND-75 09871886290 Scanned with CamScanner se 2 b) both TAS and mach number will increase. ¢) the TAS will decrease and the mach number will increase. d) the TAS will increase and the mach number will decrease. _— Cruising at FL390, M 0.84 is found to give a TAS of 499 kt, The ISA deviation at this level will be: a)-17 b) +17 ) +19 d)-19 The errors to which the machmeter is subject are: a) instrument error, position error, compressibility error and manoeuvre induced error. b) instrument error, position error. OX ¢) instrument error, position error, barometric errortemp ature error and manoeuvre induced error. 4) instrument error, position error, density erforgnd manoeuvre induced error. a\ 8. The relationships between TAS mach we and local speed of sound (LSS) is: e a) LSS = MNo TAS b) MNo = LSS. fas 7 Me oe TAS ¢) TAS = Mioxt$5 2 d) MNo = LSS*T aS 9. The mat imeser gives an indication of mach number by measuring the ratio: a) pitot pressure ic pressure st bystatic’pressure , ‘dynamic pressure Xs) dynamic pressure pitot pressure d) dynamic pressure static pressure Scanned with CamScanner 3 cewree 28 LC710. An aircrafts flying at FL350 with a JSA deviation of +8. The mach no is 0.83 and the TAS 485, If the aircraft descends to FL300 and maintains the same mach no and TAS, the JSA deviation will now be: a) 48 b)-2 c)42 d)-18 Ss ss fi f2fsfafs]o {7} ster rife tele brle [3 a fo ic MACHMETER Ss 1. Determine the TAS corresponding to 0.70 M at JSA My L(+ 15°C or 288°K). q A Sw 2. Calculate the altitude in the atmosphere at whictha TAS of 450 knots corresponds to Mach .80 lute which Is equal ta- 64°C) 3. If a decrease of 0.12 in the Mach Number results in a decrease of80 Knots in the TAS, what is the local speed of soun; With a TAS of 467 Knots at Mach No 0.8 when the 4. An aircroft is flying at, temperature differes yn ISA is +9. What is the Temperature difference at FL320 if TAS of 467 Knots. Mach 0.8 still gi CAS 5.At fight level 330 the RAS of an aircrafts 285kt. The temperature deviation from the standard isla (USA). Use your computer to determine: The TASS< a) \S564kts bh, \454 kts< ¢) ~ 530kts Xd) 480 kts eA 8 The local speed of sound ~ a) = 480 kts b) —-530kts cd) S64kts© d) 6 29kts SAHIL KHURANA SEC- 7, DWARKA,ND-75 Scanned with CamScanner e . 3 The mach number ) a 75 b) 80° a 1.02 d) 85 6. Coleulate, without using the computer, the altitude in the standard atmosphere at A Which 470kt TAS corresponds to Mach 0.82. a) FL283 b)— FL207 c)— FL360" qd) FL310 w in herAs what is 7. If'a decrease of 0.13 in the Mach number results in a decrease of 77kt the real speed of sound? a) —-650kts b) -394kts c) —-875kts ~~ d) 592 ktse e 8. An aircroft is at FL350, TAS 463kt at Mach azawhinshe temperature deviation from standard is +9C. Without using the computer. givethe temperature deviation at FL 310 ld give a TAS of 463kt- vr which at Mach 0.79 wor o) +42 b) 4620 d 4) ‘Scanned with CamScanner & Lmafls > oreGh Cres? 9 dtakic da 9 ddan ae cl of vor. oa WEE] as mmeecomemane a It measures rate of change of atmospheri i of rate of climb or descent Y Static in insi¢ ule | Also fed to a sealed unit through a fji=) 11% uals (Coastriction )[Ch my In Meterin« it gir can_only escape at a . - ) we VERTICAL SPEED INDICAYOR METERING UNIT? CHOKE ror mou wor cveres, “A + When A/C climbs, Static Pressure begins to'fallond is instantaneously sensed in copsule + Airreoches the casing at the controlled rate and causes the capsule to contract, driving the pointer to indicate climb . + During descent capsule will expond ST rr rn S enronsorvsy | Bioline - 'UMENT ERROR - Manufacturing tolerances Lemtine” ho Le Mire InsTRomenT , 4 i Rt Ain tic. (PRESSURE ERROR Incorrect sto Pos iow / Pe oee ail ‘he pointer takes o few seconds to steady becouse of the time token to build up 0 sure difference on limb or descent. a ss & YX ITs re will also be o time log on levelling out becouse of the time taken for the pressures to ~ BE cate is error is most noticeable ofter a prolonged climb or dese ant, especially at a high rate. USE OF LAG ERROR INSTRUMENT ALWAYS UNDERREAD. WhD+~ A 3 amc /sLOCKAGE — Permanently Zero reading_Unlike Altimeter not of feReay tem “ince it measures only the change in Air Press BASIC VSI fs inherent time ag. SSAHIL KHURANA SEC: 7. DWARKA,ND-75, Scanned with CamScanner a {thigh Performance A/C on instantaneous sespanse Is necessary DASHPOT ACCELEROMETER is used to eliminate the Lag in [VSI Instantaneous VSI) Disadvantage It causes a temporary false indication of climb on entering a turn in level cy flight Ne THE INSTANTANEOUS VERTICAL SPEED INDICATOR ) + Toovercome the problem of lag, the instantaneous Vertical Speed indicatdr(.VS.) incorporates an accelerometer unit (dash-pot or vane) which responds quickly to a change of altitude. The piston in the vertical acceleration pump immediately rises inthe cylinder and increases they . pressure in the capsule. & + The capsule expands ond the pointer wil give on ie indication of descent. | Errors Peculiar to the IVS} - Becouse ofthe sensitivity of the dash-pot assembly, the instrument tends to overeat flying conditions and small fluc ic Id be ignored. = “\ Ifthe aircraft should be turning, the piston il tend to sink towards the bottom of the cylinder ond there will be an indication of a climb... ia Paa AhimdL SS a) The instrument sholild 4 zero, or the error should be within the issible limits = Hs £200 feet Ay ite at temperatures - 20% + 50% li) £300 fge! inute outside these temperature: SERVICEABILITY CHECKS On the Ground, Scanned with CamScanner ce ~~~ vwwwewecce Because the VSI m' valueg of static pressure, position error: *~ a) never affects VSI indications. b) only causes errors in -off run. c) causes errors in time there is a chang VER "TICAL SPEED INDICATORS Wie 4. During a missed approac! ‘go-around procedure the change of aircraft attitude plus raising of the landing gear and ‘changing of flap settings ca” 4 cause short term unpredictable errors In certain instruments. The instruments «y most likely to be affected in this case are: ay 4) the altimeter, artifical horizon and vertical speed indicator. &» b) the airspeed indicator, machmeter and vertical speed indicator. @)} a ¢) the machmeter, airspeed indicator, altimeter and vertical speed indicator. d) the vertical speed indicator, airspeed indicator and altimeter. 2. The vertical speed indicator indications may be in error for site seconds after starting or finishing a climb or descent. The error igarresult of: a) a combination of time lag and manoeuyes. induced,e(rors. b) a combination of position error'and fmanoeuvre induced errors. c) manoeuvre induced errors only. © x dd) a combination of time lag and instrumen (gt. rs a 3, The advantage of having the VSI dial resentation in logarithmic spacing rather than in linear spacing is that». : a) at low rates of climb or descent the pointer movement is much largerand so is more easily read. w=,” b) readings are instantan¢o 8. c) a greater range of rate: tii and descent is shown. d) the internal mechapisqyis simplified by deletion of the calibration choke. 4. In the IVSL tlic [iwsraatneous VSI J. a) is ssinieatga feeding a sample of static pressure to the case and delaying it to the capsule. b)is vitwally ‘eliminated by using @ special dashpot accelerometer assembly. SS inated by the use of logarithmic presentation. is ly eliminated when initiating a climb or descent. essure and not actual easures rates of change of static pre the VSI during the take: whenever airspeed is changed, if at the same VS! indications e in position error. SAHIL KHURANA /ARKA,ND-75 Scanned with CamScanner OY a 4d) causes errors in VSI indications whenever airspeed is changed, even if there is no change in position error. 6. When entering a steep tum, an IVS/is likely to show: a) no change in altitude. b) a slight climb. Rs c) a slight descent. d) a slight descent at high airspeed only. 7. If the static vent becomes blocked during a climb: a) the VSI will stop at the rate of climb of the aircraft at the time of bidckage. ( b) the VSI will indicate a decreasing rate of climb. ( ¢) the VSI will return to zero. nw C d) the VSI will indicate an increasing rate of climb AS 8. In conditions of clear air turbulence: a) the standard VSI is more sensitive. b) the IVSI is more sensitive. c) both types will react the same. . d) the vertical acceleration pump will not Be offectes 9. Change of temperature as an acer ift climbs or descends: a) will affect VSI readings whenever‘témperature lapse rate differs from standard conditions. ws id orifice. b) is compensated at the metering unit by means of a capillary an aX , - aan c) has no effect on theVShas only static pressure is used in this instrument. d) may be allowed fon by use of tables or computer. 10. Permissible lngits of accuracy of the VSI are temperaturecange Of + aNd ....... outside this range. a)t 250 fpmyon the ground, -20°C to +50°C, + 300 fpm b) + 200 fpm, at any height, -20°C to +30°C, + 300 fpm cJ+t.250 fom, at any height, -20° to +50°C, # 300 fpm d) 4-200 fpm, on the ground, -20°C to +50°C, + 300 fpm [21 3 aA] A enum vurpanta Scanned with CamScanner i pad 7 ogy BAS vs, ba! nino > ae, - spor & rot ni yer ot 2 34 $ — AIR DATA COMPUTER ‘The Air Data Computer in current aircraft is a device that uses analogue or digital computing Sechniques to convert pressure and temperature data into electrical signals which are transmitted to the display instruments and to other systems. in many large aircraft currently in service, the conventional pressure Instruments which show a\ altitude, airspeed ond Mach Number(M No.) are replaced by indicators displaying information, > generated by o central computer, the Air Data Computer (ADC). efficiencies due to Positioning of the gathering probes and this information can then be enter Into the compe ta een thermo acnate nan pone, rad Gee The standard ADS instruments show altitude, vertical speed, airspeed and M NoxAddltinal instruments can display Total Air Temperature (TAT), Stati Air Temperature (SAT) and TAS. — ' = ee. Anfads. (mi LO outtots N 4! Sn <~ z TOO ee ee ew er ee CI CI OIC Schima ALTITUDE i “ALERTER:. fink v Ps VERTICAL SPEEO, “INDICATOR | SPEED WARN j instruments sul a ‘output signals: are ved to iospeateus various flight instruments and aeroplane systems. The flight a, Q /irspeed Indicator, Scanned with CamScanner 38 O Vertical Speed Indicator Q Machmeter — The aeropiane systems typically supplied are the: HO Flight Data recorder (FOR) ~ Wa | Flight Management System (FMS J AD autos Automatic Flight Control System (AFCS) Fk Kt transponder owls Lell Ayr dud ’ ponder Qewels Catt Mgrs Crd Xf Ground Proximity Warning System (GPWS)_ SLY 2 Power Management Computer (PMC), KK 0 Flight Director system (FDS) . — O Altitude gas 4) a O Vertical speed Qa Margioymber cpl Pr yee Scanned with CamScanner AIR DATA COMPUTER (ADC) 1. An air data computer (ADC)? @. Measures position error in the static system and transmits this information to ATC to provide correct altitude reporting b. Transforms air data measurements into electrical impulses driving ‘ \ servo motors in instruments © c. Is an auxiliary system that provides altitude information in the ry : event that the static source is blocked. d. Converts air data measurements given by ATC from the aro it jn ' order to provide correct altitude and speed information:,_/ In an ADC, aeroplane altitude is calculated from?. aN a. The difference between absolute and dynamic pressure at the fuselage a b. Measurement of outside air temperatitre, » (OAT) c. Measurement of elapsed time for @ radio signal transmitted to the ground surface and back = d. Measurement of absolute barometric pressure from a static source 5) on the fuselage. - et == : U. ‘Satie Poxi : ae \y 3. The advantage ibe ed by an ADC to indicate the altitude are: 1. Position/pre: re ‘error correction — 2. Hysteresisgn ror correctiono<— ta transmission capability_. 3. Remot 4. Capability to feed data to a large number of instruments WX ultaneously_~ v The combination of correct statement is? . 1,2,3,4 Mo* b. 23,4 x Ss c 12,3. oy a d. 13,40 4, What advantage are provided by an ADC, compared to traditional pitot static systems? SAHIL KHURANA SEC-7, DWARKA,ND-75 Scanned with CamScanner 1. Instrument lag is reduced or eliminated ~~ 2. Position error is automatically correct for ~ 3. Compressibility error is automatically corrected. foo 4. Allarge number of instruments can be fed form one ADC 5. It provides emergency altimeter following main system failure a. 1,3,4,5 b. 1,2,3,4 ©. 23,45 > © d. 1,2,4,5+ 5. From where does the ADC obtain its altitude data? vr a. Barometric information from the static pressuce-Rorts * b. Barometric pressure from the pitot probe & c. The difference between pitot and staticpressures \ 7 & 6. What inputs are fed to the ADC? « 1. AOA 4 2. TAT“ e 3. OAT = 4. Dynamic pressure \> 5. Static pressure ~ Y Isdefinedasan ee ‘change in direction of the spin axi external force aA, Y Greater the opplied force greater the . slower the rate of précéssion ill not act at the point of GPP rater, but will oct Sy yr LP 6 Gree Y “Ta force is applied to 0 moving rotor, it wil ata point. 90; megesed in the direction of rotation (3. GIMBAL * Js.a device that supports a GYRO but allows itta mave Freely, Gyro is mounted ona Gimbal “<~ ir oN ve (4. TYPES OF GYRO a) Free (space) Gyro| (macy b) Tied Gyro (Dy YS) Ye cc) Earth Gyro, heuara~ : d) Rate Gyro BY Tum deel D amducalor, e) Rate integrating Gyro(- NG) /hich it is set, whether in horizontal or vertical 5. WANDER “AY Deviation 9 gyro o axis, from given direction to w! Of eA WANDER ctually shifts relative to space. It is coused bymechanical imperfections wine including friction 0 "7. APPARENT WANDER Sis due to effect af earth's rotation. Pat ne horizontol plane (Azimuth) ©) ort Lt 8. DRIFT When spin oxis shifts in the horiz 9. TOPPLE When spin oxis shifts in the vertic vertical plane © SAHIL KHURANA cer. 7 MWARKA.ND-75 Scanned with CamScanner ea eae ee ee oe ew orerr NO Use w Ak 2 wu tex pw ay F a ep decreosing.ot 15°XSintat/hout 40. APPARENT DRIFT ; ‘Due to rotation of Eorth. In NH heading will kes oor “will remain aligned in space with meridian (north). Reason ~gyr0 nei insu dg, will increase ot 15°X Sintot/ Nour. cs I 2 VEX COS O a1.appanentropeie | | PLE = Sx CE vA vertical oxis gyro will suffer opporent wonder = 15 Costot/ OW vel x [HORIZONTAL AXIS GYRO- L (. DRIETAT POLES —— TICAL AXIS GYRO - MAX TOPPLE AT EQUATOR & O ——__TOPPLE AT POLES, —WaAK DRIFT 15 15°/HHr & OCCURS AT POLE REMAX. | = MAX TOPPLEIS 15° /Hr & OCCUR STATIONARY HORIZONTAL AXIS PERSON LOOKING NORTH. no.on SPACE GYRO™ (egress al Ireedom oj : d {LEREE GYRO OR SPACE GYRO ~ Gyro hos, freedom of movement, in three plones at right angles to each other precession of ony ayro Is same os Its no. [0 GYRO ron \ ithas freedom of movement in 3 planes but one istied. °? “Tehas freedom of precession in about 2 axes RO WITH NO REAL WANDER ) "PERSON \W/ LOOKING NORTH. SEES 290° of gicbl -Ne- v. seca application in aircroft egre of frelon Ce Plane 6f sprssdlom- ig of qunbalr’ = ¥ tis controlled by an external force or one oxis is restricted to maintain in a particular 8 direction ce Used in DG! { Direction Gyro Indicator) 3. EARTH GYRO Y itis tied gyro thot is cont ravit or one. i Used in Artificial Horizon wy" SAHIL KHURANA, SEC 7, DWARKA,ND-75 noa71acK20n Scanned with CamScanner 41 4. BATE Gyno * lirection Athos one plane of freedom It in YI Senses rate of change rather than degree of chonge Y Used in TSI ( Turn & Slip Indicator } 5. RATE INTEGRATING GYRO ¥ tis ree of freedom gyro. ‘Senses rate of movement about one axis only Y’ Used in inertia! Nav. System Used in inertial Nav. System Y Used to keep platform horizéntal in INS SUMMAR) GYROSCOPES Gyroscopic inertia or Rigidity in Space is the property of a spinning body to maintai direction in space unless acted on by an outside force. ad Precession is the movement of a gyro, resulting from the application of argu! axis perpendicular to both the spin axis and the applied force. Oo Real Wander isa precession coused by mechanical imperfections (suchas Jneven bearing friction) or by any applied force. qj Apparent Wander is the observed wander of a gyro rotor og fine toa datum on the earth. icatplane. Topple is rotor axis wander - real or apparent - in the Drift is rotor axis wander - real or apparent - in the hon’ ide force, about an tal plane, ‘Space Gyro hos complete freedom in three mutually Berpendlculor planes, and so hos gyroscopic inertia relative to a point in space. = in a desired position. A Tied Gyro has the rotor oxis maintaine: An Earth Gyros a meee gyro, so having gyroscopic inertia relative to the earth's vertical. Rigidity This property; sete provide a directional datum. "indicator (0G!), the rotor spin axis is horizontal and so provides a reference In the Directional for the mee of direction in azimuth (aircraft heading). In eniby prorat gyroscopic rigidity provides a pitch and roll attitude reference, the spin the earth's vertical. d i As already explained, the application of an external force to a gyro produces movement of the rotor axis called precession. This property is used:- a) In the Rate of Turn Indicator - to measure angular velocities in the yawing plane. is in the yawing plane. Additionally, to BS b) In the DGI control system - to maintain the rotor nally, to ) compensate DGI wander by means of a ‘latitude nut’, ‘¢) In the Artificial Horizon control system = to maintain the rotor axis vertical. / . i ‘Scanned with CamScanner

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