CAN YOU READ THIS AND THIS
Nov 07, 2014
CAN YOU READ THIS
AND THIS
GYRO STEERING
INTRODUCTION• MAGNETIC REFERENCE UNRELIABLE
CLOSER TO MAGNETIC POLES• UNCOMPENSATED GYRO USED AS
HEADING REFERENCE• HIGHLY ACCURATE GYRO MAKE
BETTER HEADING REFERENCE THAN BEST OF GYRO-MAGNETIC COMPASS
AIM
THE AIM OF THIS CLASS IS TO LEARN GYRO STEERING TECHNIQUE AND
USE OF UNCOMPENSATED GRYO AS A HEADING REFERENCE
TIE IN AND REVISION
GYRO DRIFT• REAL DRIFT• APPARENT DRIFT EARTH RATE = 15.04 X SIN λ (°/HR) TRANSPORT WANDER
= G/SPD X SIN TRK X TAN λ60
CORRECTION FOR DRIFT• REAL DRIFT –SYSTEMATIC DRIFTS CORRECTED
FOR DURING CALIBRATION.• RANDOM DRIFT CAN ONLY BE CORRECTED AS A
SHORT TERM MEASURE BY OBSERVATION OF DRIFT RATES OVER A SHORT PERIOD
• APPARENT DRIFT – CALCULATED AND APPLIED IN REVERSE SENSE.
• ON PLOTTING CHART, RESIDUAL APPARENT DRIFT DUE TO DIFFERENCE BETWEEN EARTH AND CHART CONVERGENCE REMAINS
= CHLONG [SIN MEAN LAT – n] (°/HR) WHERE N = CONSTANT OF THE CONE FOR THE PROJECTION
PHASE I
ADVANTAGES OF USING GYRO STEERING
• GYRO TRACK WILL BE A GREAT CIRCULAR TRACK
• THE PROBLEM OF USING MAGNETIC COMPASS AT HIGHER LATS
• USE OF GRIDED CHARTS WILL MAKE THE PLOTTING AND HEADING MAINTAINENCE EASIER
UNCOMPENSATED GYRO TECHNIQUE
• GYRO ALIGNMENT• GYRO DRIFT CORRECTION• GYRO STEERING• MAINTAINENCE OF AIRPLOT AND
TRACKPLOT• FIX PROCEDURES
UNCOMPENSATED GYRO TECHNIQUE
GYRO ALIGNMENT • INITIAL ALIGNMENT W.R.T. MAGNETIC
NORTH• INCASE USING A GRIDED CHART THEN
THE GYRO CAN ALSO BE ALIGNED TO THE GRID DATUM
• ALTERNATIVE METHOD IS TO ALIGN THE GYRO W.R.T. ASTRO HEADING CHECK OR BY DATUM POINTS ON GROUND
UNCOMPENSATED GYRO TECHNIQUE
GYRO DRIFT CORRECTION • APPARENT DRIFT RATE BE CALCULATED
AND AIRCRAFT HEADING ADJUSTED TO ALLOW FOR THE EFFECT OVER A PERIOD OF TIME, REAL DRIFT RATE IS OFTEN OF COMPARABLE VALUE, AND MAY BE OF OPPOSITE SIGN
• THEREFORE, DETERMINE TOTAL GYRO DRIFT RATE BEFORE MAKING ANY HEADING CORRECTIONS
GYRO DRIFT CORRECTION
• NUMERICALGYRO COMPENSATED FOR EARTH
RATE AT 30 DEG NHDG 045 ON LAT 60N SPEED 400 KTSREAL DRIFT 12DEG/HR• WHAT IS THE TOTAL GYRO DRIFT?
• 25 DEG DEG/HR
• IF AIRCRAFT FLIES SOLELY BY REFERENCE TO HIGH DRIFT RATE GYRO, IT WILL BE FOLLOWING A CURVED PATH, EVEN THROUGH INDICATED GYRO HEADING REMAINS UNCHANGED
GYRO STEERING
GYRO STEERING
• AIM OF UNCOMPENSATED GYRO STEERING IS TO CALCULATE AVERAGE HEADING THAT HAS BEEN FLOWN AND TO DETERMINE NEXT GYRO HEADING TO BE STEERED IN ORDER TO MAKE GOOD NEXT DR TRACK/HEADING
DEFINITIONS
• INITIAL HEADING TRUE OR GRID HEADING OF AIRCRAFT AT BEGINNING OF GYRO STEERING PERIOD.
• FINAL HEADING TRUE OR GRID HEADING OF AN AIRCRAFT AT THE END OF GYRO STEERING PERIOD. THIS HEADING MAY BE DETERMINED BY ASTRO.
• DIFFERENCE BETWEEN THIS AND INITIAL HEADING IS GYRO DRIFT FOR THE PERIOD
GYRO STEERING
DEFINITIONS
• DESIRED HEADING TRUE OR GRID HEADING DETERMINED BY NORMAL NAVIGATIONAL METHODS WHICH IS DESIRED TO FLY FOR SOME TIME AHEAD
• GYRO STEERING PERIODS PERIOD INTO WHICH A FLIGHT IS DIVIDED TO ASSESS AND ALLOW FOR GYRO DRIFT
GYRO STEERING
DEFINITIONS
• AVERAGE HEADING MEAN OF THE INITIAL AND FINAL HEADINGS FOR ANY REQUIRED PERIOD. IT IS USED TO MAINTAIN AIR PLOT IF REQUIRED. THE AIM OF GYRO STEERING IS TO KEEP AVERAGE HEADING AS CLOSE TO DESIRED HEADING AS POSSIBLE
GYRO STEERING
GYRO DRIFT DURING PERIOD
FINAL HEADING
INITIAL HEADING
AVERAGE HEADING ASSUMED THROUGHOUT
1030 1050
CONSTANT GYRO HEADING
GYRO STEERING
AVERAGE HEADING
GYRO STEERING
• USUALLY TIME INTERVAL BETWEEN TWO HEADING CHECKS IS APPROX 20 MINUTES, ENABLING HEADING TO BE READJUSTED TO COMPENSATE FOR GYRO DRIFT BEFORE AIRCRAFT IS FAR OFF- TRACK
GYRO CORRECTION GRAPH
• TOTAL DRIFT OF A GYRO AT ANY TIME IS EQUAL TO THE DIFFERENCE BETWEEN GRID HEADING AND GYRO READING
• GYRO DR=GRID HDG-GYRO READING• THIS DIFFERENCE IS COMPUTED AT THE TIME
OF HEADING CHECKS AND IS PLOTTED ON A GRAPH AS A GYRO CORRECTION
• THE GRID HEADING FOR ANY TIME CAN BE DETERMINED BY EXTRACTING THE GYRO CORRECTION FOR THAT TIME FROM THE GRAPH AND APPLYING IT TO THE GYRO READING
GYRO STEERING
GYRO CORRECTION GRAPH
• AVERAGE HEADING CAN BE FOUND BY EXTRACTING GYRO CORRECTION FOR MID TIME OF THE PERIOD AND APPLYING TO GYRO HEADING STEERED
• GYRO READING TO STEER IS DETERMINED
BY APPLYING AVERAGE CORRECTION EXPECTED FOR THE NEXT PERIOD TO DESIRED HEADING
GYRO STEERING
GYRO CORRECTION GRAPH
• AVERAGE CORRECTION IS PREDICTED BY EXTENDING THE GYRO DRIFT LINE TO MID TIME OF THE NEXT PERIOD
• HEADING CHECKS AND ALTERATIONS MAY BE ACCOMPLISHED AT ANY TIME, AND AS LONG AS GYRO READINGS STEERED ARE RECORDED, AVERAGE HEADINGS CAN BE COMPUTED
GYRO STEERING
ACTIVITY CYCLEPRE FLIGHT SET UP THE GYRO MODE OF
OPERATION. IT INCLUDES• SETTING LOCAL GRIVATION• SYNCHRONISING AND CHECKING
COMPASSES• SELECTING DG MODE OF OPERATION• ZEROING THE VSC• FINALLY CHECK ALL COMPASS READINGS
GYRO STEERING
ACTIVITY CYCLEIN FLIGHT, REGULAR CYCLE IS MAINTAINED.
IT INCLUDES• CARRY OUT ASTRO HEADING CHECK• CARRY OUT COMPASS COMPARISON• PLOT GYRO CORRECTION• PREDICT AVERAGE GYRO CORRECTION• ALTER HEADING AS REQUIRED TO
MAINTAIN TRACK
GYRO STEERING
ACTIVITY CYCLEIN FLIGHT, FIRST THREE HEADING CHECKS
TAKEN IN QUICK SUCCESSION TO ESTABLISH INITIAL ALIGNMENT ERROR AND ANY LARGE DRIFT TENDENCY. THEREAFTER A CYCLE OF 20 MIN IS FOLLOWED
GYRO STEERING
CALCULATION OF GYRO READING (GR) FOR A DESIRED GRID HEADING (GH) OF SAY 015° AND A PREDICTED AVERAGE GYRO CORRECTION (GC) OF + 7˚ WILL BE
GH – GC = GR 015° – (+ 7˚) = 008˚
GYRO STEERING
FIX PROCEDURES• NDB AND RELATIVE RADAR BEARING:
APPLY SPOT GYRO CORRECTION FOR THE TIME OF BEARING TO GYRO READING TO OBTAIN GRID HEADING. ADD BEARING TO GRID HEADING AND PLOT RECIPROCAL AS GRID BEARING
• GYRO / COMPASS ORIENTED RADAR BEARINGS: THESE WILL BE IN GRID AND WILL REQUIRE CORRECTION FOR GYRO ERROR
FIX PROCEDURES
• VOR AND TACAN: RADIALS CAN BE PLOTTED DIRECTLY FROM MAGNETIC MERIDIAN THROUGH THE STATION. IF DESIRE TO PLOT GRID BEARINGS, THEN MAGNETIC BEARING TO BE CONVERTED TO GRID BEARING BY APPLICATION OF THE VALUE OF GRIVATION AT STATION
FIX PROCEDURES
• PIN-POINTS: PIN-POINTS AND FIXES FROM HYPERBOLIC RADIO AIDS SHOULD BE TRANSFERRED FROM APPROPRIATE CHART TO GRID CHART IN TERMS OF THEIR GEOGRAPHICAL CO-ORDINATES
FULLY COMPENSATED GYROGYRO ALIGNMENT
• ACCURATE INITIAL ALIGNMENT OF GREAT IMPORTANCE
• PROBLEM OCCURS IF GYRO IS ALIGNED TO MAGNETIC DATUM
• SURVEYED SITES AND RELATIVE BEARING METHODS OR RUNWAY CENTRE LINE ADJUSTMENT ARE USED
FULLY COMPENSATED GYROGYRO DRIFT CORRECTION• METHOD OF CORRECTION DEPENDS ON
TYPE OF TORQUE CONTROL IN USE
• COMBINED EARTH RATE AND RESIDUAL TRANSPORT RATE CORRECTION CAN BE CALCULATED AND SET AS FALSE LATITUDE ON EARTH RATE CONTROLLER
FULLY COMPENSATED GYROGYRO STEERING• ONCE GYRO ALIGNED TO HEADING DATUM
AND DRIFT CORRECTION RATES SET, AIRCRAFT NAVIGATED BY MEANS OF NAVIGATION COMPUTER AND NORMAL FIXING AIDS
• AIRCRAFT HEADING SHOULD BE CHECKED APPROXIMATELY EVERY HALF HOUR
• DIFFERENCE BETWEEN GYRO READING AND AIRCRAFT HEADING SHOULD BE RECORDED
FULLY COMPENSATED GYROGYRO STEERING• OVER A SERIES OF CHECKS, AVERAGE
GYRO CORRECTION CAN BE CALCULATED
GYRO CORRECTION = GRID (OR TRUE) HDG – GYRO READING
• SMALL DRIFT RATE BE REMOVED BY SETTING A FALSE LATITUDE
• FOR LARGE DRIFT RATE (3° / HR), FOLLOW UNCOMPENSATED GYRO TECHNIQUE
FULLY COMPENSATED GYROPLOTTING POSITION LINES• GYRO CORRECTION VALUE FOR THE TIME
OF BEARING IS APPLIED TO GYRO READING TO OBTAIN HEADING
FULLY COMPENSATED GYROALTERATION OF HEADING• HEADING MAY BE ALTERED AT ANY TIME
• HEADING CHECK AFTER ALTERATION OF HEADING IS USED TO CALCULATE NEW GYRO DRIFT RATE
• HEADINGS FLOWN BEFORE AND AFTER TURN ARE OBTAINED BY APPLYING GYRO CORRECTION VALUES TO GYRO READING
FIX MONITORED AZIMUTH• FMA USED WHEN ACCURATE FIXES
AVAILABLE AND AIRCRAFT FITTED WITH FULLY COMPENSATED LOW DRIFT GYRO AND NAVIGATION COMPUTER FED FROM DOPPLER
• POSITIONS GIVEN BY COMPUTER ARE COMPARED WITH ACCURATE FIXES; ANY ACROSS TRACK ERROR IS ATTRIBUTED TO MISALIGNMENT OF HEADING REFERENCE
FIX MONITORED AZIMUTH• AMOUNT OF MISALIGNMENT MAY BE
DETERMINED
• GYRO OUTPUT TO NAVIGATION COMPUTER IS RE-ALIGNED AND COMPUTER IS RESET TO THE FIX CO-ORDINATES
• FMA TECHNIQUE REMOVES REQUIREMENT OF ASTRO HEADING CHECKS
FIX MONITORED AZIMUTH
• ACCURATE AIDS MUST BE AVAILABLE AND AIRCRAFT NAVIGATION SYSTEM MUST BE FUNCTIONING CORRECTLY
• OTHERWISE CALCULATED MISALIGNMENT WILL BE INCORRECT, SINCE FIX ERRORS AND DOPPLER ERRORS WILL BE INCLUDED IN THE CALCULATION
SUMMARY
QUESTION BY THE CLASS
QUESTIONS TO THE CLASSQUESTION
ANSWER
SUMMARY AND CONCLUSION