Flight Test Data
Determining Static System Error - Version 1.0
Point 1 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt) Legend
55 7500 29 65.6 246 5.0 16 62.5 Vg
58.0 348 5.0 16 62.5 Track
62.4 107 5.0 16 62.5 Vwind
67.0 171 5.0 16 62.5 Wind dir
ave 5.0 15.9 62.5 Vtrue
std dev 0.0
Note:
Point 2 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
60 7500 30 69.6 268 5.7 12 68.4 Note:
62.8 8 5.6 11 68.4
69.0 110 5.5 12 68.5
74.0 190 5.6 13 68.4
ave 5.6 12.1 68.4
std dev 0.0
Credits
Point 3 Vwind Wind dir Vtrue The algorithm to calculate TAS from G
IAS Altitude IOAT Vg Track (kt) (deg) (kt) was developed by Doug Gray.
70 7500 31 80.6 274 6.0 10 80.2
74.2 6 5.5 5 79.7 Doug Gray's method was enhanced b
79.8 98 5.1 10 80.2 four legs, and use the redundant data
85.2 179 5.6 14 79.8
ave 5.6 9.9 80.0 The format and equations for this port
std dev 0.3 spreadsheet kindly made available by
Point 4 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
80 7500 32 91.7 272 5.5 18 90.4
84.9 7 5.8 19 90.6
88.6 91 5.9 17 90.4
95.9 176 5.7 15 90.5
ave 5.7 17.3 90.5
std dev 0.1
Point 5 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
90 7500 33 102.0 276 4.5 20 101.0
96.6 8 4.9 24 101.4
100.0 99 5.2 19 101.0
106.0 184 4.8 15 101.3
ave 4.8 19.5 101.2
std dev 0.2
Point 6 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
100 7500 33 111.0 93 4.9 22 112.6
108.0 4 5.2 16 113.1
114.0 274 5.7 19 112.7
118.0 178 5.5 25 113.1
ave 5.3 20.1 112.9
Page 1
Flight Test Data
std dev 0.3
Point 7 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
110 3500 66 87.2 266 31.6 257 118.5
124.0 4 30.6 258 119.1
146.0 103 30.9 260 118.0
104.0 190 32.7 259 119.7
ave 31.5 258.4 118.8
std dev 0.7
Point 8 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
120 3500 66 98.2 270 31.2 256 128.8
132.0 359 30.5 257 129.2
157.0 99 30.8 259 128.5
119.0 180 32.0 258 129.6
ave 31.1 257.5 129.0
std dev 0.5
Point 9 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
130 3500 67 113.0 289 29.2 256 138.4
152.0 19 27.5 257 139.3
160.0 115 27.6 261 138.0
121.0 204 30.0 260 140.0
ave 28.6 258.6 138.9
std dev 0.9
Point 10 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
140 3500 67 128.0 299 27.1 257 149.2
168.0 34 26.4 257 149.6
165.0 127 26.2 259 148.9
126.0 227 27.3 259 149.9
ave 26.8 257.6 149.4
std dev 0.4
Point 11 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
150 3500 68 136.0 285 25.8 261 159.9
170.0 18 27.0 260 159.3
181.0 114 26.9 257 160.3
142.0 206 25.2 258 158.8
ave 26.2 259.0 159.6
std dev 0.7
Point 12 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
160 3500 68 144.0 283 27.7 260 169.8
172.0 359 27.6 260 169.8
196.0 97 27.6 260 169.8
161.0 184 27.7 260 169.9
ave 27.6 259.9 169.8
std dev 0.0
Page 2
Flight Test Data
Point 13 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
170 3500 68 153.0 265 27.3 258 180.1
181.0 354 23.4 265 183.0
206.0 95 26.6 273 179.4
184.0 169 30.7 264 183.7
ave 27.0 265.1 181.6
std dev 2.1
Point 14 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
180 1500 71 165.0 184 29.6 239 183.8
157.0 266 29.3 237 183.2
197.0 359 28.6 237 183.6
207.0 90 28.7 239 183.0
ave 29.1 237.9 183.4
std dev 0.3
Point 15 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
ave
std dev
Point 16 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
ave
std dev
Point 17 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
ave
std dev
Point 18 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
ave
std dev
Page 3
Flight Test Data
Point 19 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
ave
std dev
Point 20 Vwind Wind dir Vtrue
IAS Altitude IOAT Vg Track (kt) (deg) (kt)
ave
std dev
Page 4
Flight Test Data
GPS ground speeds in kts on the four different legs (not necessarily 90 deg apart)
GPS track of the corresponding legs
Calculated wind speed
Calculated wind direction (deg mag)
Calculated aircraft true airspeed
Each point assumes that the four legs are flown at the same
airspeed, altitude, and with the same wind.
Intermediate calculations exist in hidden columns (C through U). To
add new points, these columns need to be copied as well as the
visible columns. To do this span the hidden columns and copy.
The algorithm to calculate TAS from GPS ground speed and track recorded on three legs
was developed by Doug Gray.
Doug Gray's method was enhanced by the National Test Pilot School – they record data on
four legs, and use the redundant data to provide a quality control check.
The format and equations for this portion of the spreadsheet were copied from the “GPS PEC/XLS”
spreadsheet kindly made available by NTPS.
Page 5
Data Analysis
Determining Static System Error - Version 1.0
CONSTANTS
K 0.5 recovery factor of OAT probe
ASI units (kt, mph, or km/h kt enter kt, mph or km/h
GPS units kt enter kt, mph or km/h
IOAT units F enter F or C (degrees Celsius or Fahrenheit)
Reference altitude (ft) 8000 altitude to correct data to
INPUTS
Airspeed Altimeter IOAT
Run IAS ASI IAS IAS Indicated Altimeter Pressure Indicated
(ASI inst. corrected corrected Pressure inst. altitude OAT
units) error for inst. for inst Altitude error corrected
Error (ASI error (kt) for inst.
units) error
(kt) (kt) (kt) (kt) (ft) (ft) (ft) (deg F)
Vi dVic Vic Vic Hi dHic Hic Ti
1 55 1.2 56.2 56.2 7,500 0 7,500 29
2 60 1.1 61.1 61.1 7,500 0 7,500 30
3 70 0.9 70.9 70.9 7,500 0 7,500 31
4 80 0.8 80.8 80.8 7,500 0 7,500 32
5 90 0.6 90.6 90.6 7,500 0 7,500 33
6 100 0.5 100.5 100.5 7,500 0 7,500 33
7 110 0.3 110.3 110.3 3,500 0 3,500 66
8 120 0.2 120.2 120.2 3,500 0 3,500 66
9 130 130.0 130.0 3,500 0 3,500 67
10 140 0.1 140.1 140.1 3,500 0 3,500 67
11 150 0 150.0 150.0 3,500 0 3,500 68
12 160 -0.3 159.7 159.7 3,500 0 3,500 68
13 170 -0.6 169.4 169.4 3,500 0 3,500 68
14 180 -0.8 179.2 179.2 1,500 0 1,500 71
15 0 0 0 0
16 0 0 0 0
17 0 0 0 0
18 0 0 0 0
19 0 0 0 0
20 0 0 0 0
Page 6
Data Analysis
ahrenheit)
INTERMEDIATE CALCULATIONS
TAS
True Standard TAS OAT (IOAT OAT (IOAT True Mach qcic/Psl qcic/Ps
Airspeed Deviation of Corrected for Corrected
(GPS units) TAS Ram Temp. for Ram
Rise) Temp. Rise)
(kt) (kt) (kt) (deg K) (deg F) Mach
Vt Vt T M qcic/Psl qcic/Ps
62.5 0.0 62.5 271.2 28.5 0.0974 0.0051 0.0067
68.4 0.0 68.4 271.7 29.4 0.1065 0.0060 0.0079
80.0 0.3 80.0 272.2 30.2 0.1244 0.0081 0.0107
90.5 0.1 90.5 272.6 31.0 0.1406 0.0105 0.0138
101.2 0.2 101.2 273.0 31.8 0.1571 0.0132 0.0174
112.9 0.3 112.9 272.9 31.5 0.1754 0.0163 0.0215
118.8 0.7 118.8 291.1 64.3 0.1787 0.0196 0.0223
129.0 0.5 129.0 290.9 64.0 0.1941 0.0233 0.0265
138.9 0.9 138.9 291.3 64.7 0.2089 0.0273 0.0310
149.4 0.4 149.4 291.1 64.4 0.2247 0.0318 0.0361
159.6 0.7 159.6 291.5 65.0 0.2399 0.0365 0.0414
169.8 0.0 169.8 291.3 64.6 0.2553 0.0414 0.0471
181.6 2.1 181.6 291.0 64.1 0.2731 0.0467 0.0530
183.4 0.3 183.4 292.6 67.0 0.2751 0.0523 0.0553
#VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
Page 7
Data Analysis
ULATIONS RESULTS
Test Altitude
Indicated dPp/Ps dPp/qcic Pressure Calibrated Airspeed Total Altitude
Mach Altitude Airspeed Position Airspeed Error at Test
(CAS) at Error at Test System Altitude
Test Altitude Altitude Error at Test
Altitude
(ft) (kt) (kt CAS) (kt CAS) (ft)
Mic dPp/Ps dPp/qcic
0.0976 0.0000 -0.0049 7,499 56.1 -0.1 1.1 -1
0.1061 0.0001 0.0075 7,502 61.3 0.2 1.3 2
0.1231 0.0002 0.0206 7,506 71.6 0.7 1.6 6
0.1403 0.0001 0.0043 7,502 81.0 0.2 1.0 2
0.1573 0.0000 -0.0022 7,499 90.5 -0.1 0.5 -1
0.1745 0.0002 0.0104 7,506 101.0 0.5 1.0 6
0.1777 0.0003 0.0116 3,507 110.9 0.6 0.9 7
0.1936 0.0001 0.0052 3,504 120.5 0.3 0.5 4
0.2094 -0.0001 -0.0047 #VALUE!
0.2256 -0.0003 -0.0083 3,492 139.5 -0.6 -0.5 -8
0.2415 -0.0006 -0.0135 3,485 149.0 -1.0 -1.0 -15
0.2571 -0.0006 -0.0135 3,483 158.6 -1.1 -1.4 -17
0.2727 0.0002 0.0029 3,504 169.6 0.2 -0.4 4
0.2782 -0.0012 -0.0217 1,467 177.3 -1.9 -2.7 -33
#VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE!
#VALUE! #VALUE! #VALUE! #VALUE!
Page 8
Data Analysis
SULTS DATA FOR GRAPHS
Reference Altitude
Airspeed Total Airspeed Altitude IAS Airspeed
Position System Error Error at corrected Position
Error at (Instrument Reference for inst. Error at
Reference Error + Position Altitude Error (ASI Test
Altitude Error) units) Altitude
(kt) (kt) (ft) (kt) (kt CAS)
Vic
-0.1 1.1 -1 56.2 -0.13675
0.2 1.3 2 61.1 0.228374
0.7 1.6 6 70.9 0.725229
0.2 1.0 2 80.8 0.174214
-0.1 0.5 -1 90.6 -0.09996
0.5 1.0 6 100.5 0.515863
0.5 0.8 7 110.3 0.631301
0.3 0.5 4 120.2 0.309023
130.0
-0.5 -0.4 -8 140.1 -0.57347
-0.8 -0.8 -15 150.0 -1.00346
-0.9 -1.2 -17 159.7 -1.06502
0.2 -0.4 4 169.4 0.240686
-1.5 -2.3 -31 179.2 -1.9238
Page 9
Data Analysis
IAS Airspeed IAS (ASI Total Airspeed IAS
corrected for Position Error units) System Error corrected
inst. Error at Reference (Instrument for inst.
(ASI units) Altitude Error + Error (ASI
Position Error) units)
(kt) (kt) (kt) (kt CAS) (kt)
Vic Vi Vic
56.2 -0.133998056 55.0 1.066001944
61.1 0.224485501 60.0 1.324485501
70.9 0.71527872 70.0 1.61527872
80.8 0.171112317 80.0 0.971112317
90.6 -0.098009997 90.0 0.501990003
100.5 0.507496498 100.0 1.007496498
110.3 0.534602105 110.0 0.834602105
120.2 0.26125203 120.0 0.46125203
130 130.0
140.1 -0.483036866 140.0 -0.383036866
150 -0.843937959 150.0 -0.843937959
159.7 -0.895670942 160.0 -1.195670942
169.4 0.203364662 170.0 -0.396635338
179.2 -1.499394704 180.0 -2.299394704
0.0
0.0
0.0
0.0
0.0
0.0
Page 10
Data Analysis
IAS Altitude IAS Altitude
corrected Error at corrected Error at
for inst. Test for inst. Reference
Error (ASI Altitude Error (ASI Altitude
units) units)
(kt) (ft) (kt) (ft)
Vic Vic
56.2 -0.8544 56.2 -0.85133
61.1 1.55724 61.1 1.551592
70.9 5.76617 70.9 5.745268
80.8 1.57471 80.8 1.569006
90.6 -1.0133 90.6 -1.00963
100.5 5.83276 100.5 5.811617
110.3 6.95529 110.3 6.73479
120.2 3.71363 120.2 3.595901
130 130
140.1 -8.0502 140.1 -7.79494
150 -15.108 150 -14.6288
159.7 -17.129 159.7 -16.5857
169.4 4.14024 169.4 4.008985
179.2 -32.873 179.2 -31.3886
Page 11
Graphs
Position Error in Airspeed vs IAS
IAS Corrected for Instrument Error
1
0.5
Static Source Position Error - Airspeed
0
-0.5
-1
-1.5
-2
-2.5
0 2 4 6 8 10 12 14 16
IAS Instrument Corrected
Total Airspeed System Error vs IAS
ASI Instrument Error + Position Error
2
1.5
1
0.5
Total Airspeed Error
0
-0.5
-1
-1.5
Page 12
Graphs
-2
-2.5
0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0
IAS
Page 13
Graphs
16
Page 14
Notes
by Kevin Horton, kevin01@kilohotel.com
This analysis method is based on methods used by the USAF Test Pilot School
Complete documentation, including Version History, is available at http://www.kilohotel.com/rv8/rvlinks/ssec.html
Lots more info at http://www.kilohotel.com/rv8/phplinks/index.php?PID=47
CONSTANTS
K recovery factor for outside air temperature indicator. Assume 0.8 if the manufacturer does not spec
IAS units enter kt, mph or km/h as required to match your airspeed indicator
GPS units enter kt, mph or km/h as required to match the ground speed display of your GPS
temp units enter C or F as required to match your outside temperature indicator
Reference altitude altitude to correct data to
INPUTS
IAS indicated airspeed
airspeed instrument error positive if the actual value is higher than the indicated value
altimeter instrument error positive if the actual value is higher than the indicated value
OUTPUTS
TAS calculated true airspeed from GPS data
CAS calculated calibrated airspeed (this would equal the IAS if there was no instrument error or position
CAS error error in CAS due to position error
If corrections for airspeed indicator instrument error are entered, the spreadsheet can calculate the errors in CAS and altitude due to
If you do not put in corrections for airspeed indicator instrument error, the CAS error includes position error and instrument error.
If you do not put in corrections for airspeed indicator instrument error, the calculated altitude error is meaningless.
Page 15
Notes
om/rv8/rvlinks/ssec.html
sume 0.8 if the manufacturer does not specify another value
peed display of your GPS
if there was no instrument error or position error)
lculate the errors in CAS and altitude due to position error.
udes position error and instrument error.
ude error is meaningless.
Page 16