Report 1 - Testing flight

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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


2.1 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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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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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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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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2.2.2.2Test NotesCENTER PASSENGER


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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2.2.2.3Test NotesAFT PASSENGER


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.

Documents

Report 1 - Testing flight