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Flight Report 1Airspeed Calibration Flight
December 2014
FLIGHT REPORT I (AVF5301)
AIRSPEED CALIBRATION FLIGHT
Luiz Fernando Tolentino Vargas
Florida institute of TechnologyCollege of Aeronautics
Dr. Ralph Kimberlin
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1
Summary
This Report discusses and compares the results of the airspeed calibration using
Global Positioning System (GPS) with the Pitot-static systems data. Were measured 12 times
using Pitot-static, airspeed and altitude. And using GPS where collected Ground Speed and
GPS track. Were measured 8 points with flaps down and 4 points with flaps up. After
collected the data, were plotted the Instrument Calibration Chart for Airspeed data. Results of
these graphics from Pitot-static source were compared with Pitot-static data. The results
showed the efficiency of the GPS Method.
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2
Table of Contents
Summary ........................................................................................................................ 1
LIST OF FIGURES ....................................................................................................... 3
LIST OF TABLES ......................................................................................................... 4
1. INTRODUCTION ..................................................................................................... 5
2. TEST PROCEDURES AND EQUIPAMENT .......................................................... 8
2.1 Aircraft ............................................................................................................. 8
2.2 Test description ................................................................................................ 8
2.2.1 C.G Range and WeightPrior Flight ........................................................ 9
2.2.2 Test NotesDuring Flight ....................................................................... 11
2.2.2.1 Test NotesFRONT PASSENGER ..................................................... 11
2.2.2.2 Test NotesCENTER PASSENGER .................................................. 12
2.2.2.3 Test NotesAFT PASSENGER .......................................................... 13
3. TEST RESULTS ...................................................................................................... 14
4. CONCLUSIONS ...................................................................................................... 17
5. RECOMMENDATIONS ......................................................................................... 18
6. REFERENCES ......................................................................................................... 19
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3
LIST OF FIGURES
Figure 1- Pitot-Static System of Cherokee Six. ......................................................................... 6
Figure 2- Static pressure change with aircraft passage. ............................................................. 6
Figure 3- Piper PA-32-260 Cherokee Six. ................................................................................. 8
Figure 4- Localization of the C.G point. .................................................................................. 10
Figure 5- Aircraft envelope operation. ..................................................................................... 10
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4
LIST OF TABLES
Table 1 - C.G Range and Weight. .............................................................................................. 9
Table 2- FRONT PASSENGER DATAFLAPS DOWN..................................................... 11
Table 3-FRONT PASSENGER DATA - FLAPS UP.............................................................. 11
Table 4 - CENTER PASSENGER DATA - FLAPS DOWN. ................................................. 12
Table 5 - CENTER PASSENGER DATA - FLAPS UP. ........................................................ 12
Table 6 - AFT PASSENGER DATA - FLAPS DOWN. ......................................................... 13
Table 7 - AFT PASSENGER DATA - FLAPS UP. ................................................................ 13
Table 8 - Calibrated Airspeed for Center Seat. ........................................................................ 14
Table 9 - Calibrated Airspeed for Aft Seat. ............................................................................. 15
Table 10 - Velocities average and . ................................................................................ 15
Table 11 - Intrument Calibration Chart Airspeed - Center Seat. ............................................. 16
Table 12 - Vpc versus Vi. ...................................................................................................... 16
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51. INTRODUCTION
1. INTRODUCTION
The Airspeed Calibration is one of the most important flights testing of a new
aircraft, but it is also a hard test because it is conducted when the aircraft is unknown and
some of the methods used require flights close to the ground. Also, the data collected is
dependent of atmospheric conditions. The accuracy of airspeed provides a safe flight.
There are six speed calibration methods:
Speed Course Method
Tower Fly-by Method
Place Method
Radar Method
Onboard Reference Metod
Global Positioning System (GPS) Method
During the flight test, were used the GPS Method. The GPS Method, is a relatively
new method and came after the others methods. The GPS Method is known for presents good
results with low price.
During the flight were collected data from the Pitot-Static Instrument, which consists
of airspeed indicator, altimeter and vertical velocity indicator. An Airspeed Indicator is a
differential pressure gauge measuring the difference between total pressure and static
pressure and calibrated in airspeed.An Altimeter measures static pressure as we climb or
descend and converts that to altitude.
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71. INTRODUCTION
is aft the fuselage. The difference between this two locations is that, the underwing source is
sensitive to angle of attach and the aft fuselage source is good with stall and flow separation.
For accuracy, during the flight test is required calibrate both instrument and airplane
to avoid instrument error and position error. The instrument may be calibrated on a
calibration bench using a water manometer for airspeed and a mercury manometer for the
altimeter. For determining the position error the Airspeed Course Method can be used, where
is measured the course on the ground whose length should be at least two miles. To use this
method, the aircraft flow low enough to easily tell when the ends of the courses are crossed.
To avoid the position error, the in flight testing we have a number of possibilities. They
include: Wingtip or nose Booms, trailing bomb, or trailing cone. Another fount of error is the
type of pitot probes.
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82. TEST PROCEDURES AND EQUIPAMENT
2. TEST PROCEDURES AND EQUIPAMENT
2.1 Aircraft
The aircraft flown for the flight test was a Piper PA-32-260 Cherokee Six as shown in
Figure 3. The registration number was 3736W.
Figure 3- Piper PA-32-260 Cherokee Six.
2.2 Test description
Before the flight was calculated the total weight and Moment, based on quantity of
fuel, aircraft weight, and position and weight of each passenger. After calculated these two
values, the Total Momentum is divided by the total Weight for find the Center of Gravity.
With the values of the C.G and the total weight is possible to see if the aircraft is operating
correctly with it envelope values.
During the flight test were measured 12 times, airspeed, altitude and temperature.
Where 8 points were measured with flaps down and 4 points with flaps up. The students sited
on the center and after seats, collected the airspeed and altitude values. The test may be
performed at any altitude with smooth air. The procedure is to stabilize the aircraft on a
cardinal heading at the test indicated airspeed. Remain stabilized long enough for the GPS to
update and obtain a steady groundspeed. Then record the following data. The student in the
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92. TEST PROCEDURES AND EQUIPAMENT
front seat, using GPS, collected time, GPS groundspeed, GPS aircraft track, observed
ambient temp and aircraft heading. The data necessary for GPS Calibration are:
1. GPS groundspeed
2. GPS aircraft track
3. Observed airspeed
4. Observed pressure altitude
5. Observed ambient temp.
6. Aircraft heading
2.2.1
C.G Range and WeightPrior Flight
Table 1 - C.G Range and Weight.
Weight (Lbs)Arm Aft Datum
(Inches)
Moment
(Inches x Lbs)
Basic Weight 1897 80.66 153016.4
Pilot and Front
Passenger
165 + 200 85.5 31107.5
Passengers
(Center Seats)
225 + 212 118.1 51609.7
Passengers
(Rear Seats) 220 + 180 155.7 62280.0
Fuel 300 95.0 28500.0
Total Loaded
Airplane
3399 96.06 326513.6
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102. TEST PROCEDURES AND EQUIPAMENT
The center of gravity (C.G) of this sample loading problem is at 96.06 inches aft of
the datum line.
Figure 4- Localization of the C.G point.
Locate this point 94.65 on the C.G range and weight graph.
Figure 5- Aircraft envelope operation.
Since this point falls within the weight C.G. envolepe, this loading meets the
weight and balance requirements. The M.A.C 30.0 % .
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112. TEST PROCEDURES AND EQUIPAMENT
2.2.2 Test NotesDuring Flight
2.2.2.1Test NotesFRONT PASSENGER
Flaps position: DOWN
Table 2- FRONT PASSENGER DATAFLAPS DOWN.
TimeAircraft
Heading
GPS
Groundspeed
( Knots )
GPS
Track
( Deg )
Temperature
( )
11:28 110 96,4 105 15.5
11:30 290 90,1 301 15.5
11:31 290 79,7 301 15.5
11:33 110 86,3 110 15.5
11:34 110 74,5 111 16.0
11:37 290 71,5 299 16.0
11:38 290 65,6 297 16.0
11:40 110 66,9 114 16.5
Flaps position: UP
Table 3-FRONT PASSENGER DATA - FLAPS UP.
Time
Aircraft
Heading
GPS
Groundspeed
( Knots )
GPS
Track
( Deg )
Temperature
()
11:43 290 113,4 290 16.5
11:44 110 115,4 105 16.5
11:45 110 102,3 108 16.5
11:47 290 102,5 291 16.5
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122. TEST PROCEDURES AND EQUIPAMENT
2.2.2.2Test NotesCENTER PASSENGER
Flaps position: DOWN
Table 4 - CENTER PASSENGER DATA - FLAPS DOWN.
Time
Aircraft
Heading
Observed
Airspeed (mph)
Observed
Altitude (ft)
Temperature
()
11:28 110 109 2220 15.5
11:30 290 109 2500 15.5
11:31 290 96 2460 15.5
11:33 110 96 2080 15.5
11:34 110 87 1880 16.0
11:37 290 87 1700 16.0
11:38 290 80 1720 16.0
11:40 110 78 1720 16.5
Flaps position: UP
Table 5 - CENTER PASSENGER DATA - FLAPS UP.
Time
Aircraft
Heading
Observed
Airspeed (mph)
Observed
Altitude (ft)
Temperature
()
11:43 290 132 1740 16.5
11:44 110 131 1500 16.5
11:45 110 117 1460 16.5
11:47 290 118 1160 16.5
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132. TEST PROCEDURES AND EQUIPAMENT
2.2.2.3Test NotesAFT PASSENGER
Flaps position: DOWN
Table 6 - AFT PASSENGER DATA - FLAPS DOWN.
Time
Aircraft
Heading
Observed
Airspeed (mph)
Observed
Altitude (ft)
Temperature
()
11:28 110 110 2220 15.5
11:30 290 108 2480 15.5
11:31 290 107 2400 15.5
11:33 110 97 2040 15.5
11:34 110 86 1860 16.0
11:37 290 87 1660 16.0
11:38 290 80 1660 16.0
11:40 110 79 1680 16.5
Flaps position: UP
Table 7 - AFT PASSENGER DATA - FLAPS UP.
Time
Aircraft
Heading
Observed
Airspeed (mph)
Observed
Altitude (ft)
Temperature
()
11:43 290 132 1400 16.5
11:44 110 133 1460 16.5
11:45 110 118 1420 16.5
11:47 290 119 1120 16.5
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143. TEST RESULTS
3. TEST RESULTS
Obtaining the Airspeed Calibration:
Instrument error correction:
= +
= +
Groundspeed component:
= 1
Calculating atmospheric ratio,, and atmospheric temperature ratio, , for find and
calculate the calibrated airspeed.
=
Center Seat
Table 8 - Calibrated Airspeed for Center Seat.
Vi (mph) Vi (knots) 1 2
(knots)
109,5 95,13 2210 5 96,03 1,001735 0,959728 92,16573
109,5 95,13 2490 11 88,44 1,001735 0,954806 84,4474
96 83,40 2450 11 78,23 1,001735 0,955508 74,75481
96 83,41 2070 0 86,3 1,001735 0,962195 83,03745
87,5 76,02 1870 1 74,48 1,00347 0,964891 71,87345
87,5 76,02 1690 9 70,61 1,00347 0,968074 68,36508
80,5 69,93 1710 7 65,11 1,00347 0,96772 63,00922
78,5 68,20 1710 4 66,73 1,00347 0,96772 64,58274
132,5 115,12 1730 0 113,4 1,005205 0,966531 109,6046
131,5 114,25 1490 5 114,9 1,005205 0,970778 111,6015
117,5 102,09 1450 2 102,2 1,005205 0,971487 99,3226
118,5 102,95 1150 1 102,4 1,005205 0,976815 100,1083
109,5 95,13 2210 5 96,03 1,001735 0,959728 92,16573
109,5 95,13 2490 11 88,44 1,001735 0,954806 84,4474
96 83,40 2450 11 78,23 1,001735 0,955508 74,75481
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153. TEST RESULTS
Table 9 - Calibrated Airspeed for Aft Seat.
Vi (mph) Vi (knots) Hpi Ang. D.Gsc
Vc
(knots)
111 96,44 2205 5 96,03 0,922846 1,001735 92,17419
109 94,70 2465 11 88,44 0,914075 1,001735 84,48622108 93,83 2385 11 78,23 0,916767 1,001735 74,84414
97,5 84,71 2025 0 86,3 0,928957 1,001735 83,10596
86,5 75,15 1860 1 74,48 0,934588 1,00347 71,88661
87,5 76,02 1660 9 70,61 0,941451 1,00347 68,40258
80,5 69,94 1660 7 65,11 0,941451 1,00347 63,06684
79 68,64 1680 4 66,73 0,940763 1,00347 64,61817
132,5 115,12 1410 0 113,4 0,950086 1,005205 110,2471
133,5 115,99 1470 5 114,9 0,948008 1,005205 111,6423
119 103,39 1430 2 102,2 0,949393 1,005205 99,35886
120 104,26 1130 1 102,4 0,959834 1,005205 100,1448
111 96,44 2205 5 96,03 0,922846 1,001735 92,17419
109 94,70 2465 11 88,44 0,914075 1,001735 84,48622
108 93,83 2385 11 78,23 0,916767 1,001735 74,84414
Finally,
= +
Table 10 - Velocities average and .
(knots)
(knots)
(knots)
92,16996 95,78627 187,9562
84,46681 94,91746 179,3843
74,79947 88,61859 163,4181
83,07171 84,05734 167,129
71,88003 75,58645 147,466568,38383 76,02085 144,4047
63,03803 69,93918 132,9772
64,60046 68,41877 133,0192
109,9258 115,1173 225,0431
111,6219 115,1173 226,7392
99,34073 102,7368 202,0775
100,1266 103,6056 203,7321
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163. TEST RESULTS
Table 11 - Intrument Calibration Chart Airspeed - Center Seat.
Table 12 - Vpc versus Vi.
-0,5
0
0,5
1
1,5
70 90 110 130 150
InstrumentCorrection(knots)
Observed Airspeed (knots)
Instrument Calibration Chart
Airspeed - Center Seat
Vi
Vi cw
Vi ccw
0
50
100
150
200
250
0 20 40 60 80 100 120 140
Vpc
Indicated Airspeed (knots)
Delva Vpc
Delva Vpc
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174. CONCLUSIONS
4. CONCLUSIONS
The airspeed calibration by GPS shows being easy and quickly for flight testing. The
comparison between both pitot-static instruments presents good results. The comparison
between the pitot-static and the calibrated speed by GPS presents an average between 5 knots
of difference. Therefore the GPS calibration is very useful, and also cheap.
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185. RECOMMENDATIONS
5. RECOMMENDATIONS
The Speed Calibration by GPS was very useful, and for improves results I would
recommend increase the number of data.
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196. REFERENCES
6. REFERENCES
[1] Kimberlin, R. D. (2003). Flight Testing of Fixed-Wing Aircraft. AIAA Education Series.