Appendix 7 Figure A7-10 (continued)
4.0% 1.5% 2°
3.0% 800 700 = 2.5% 600
2.0% RATE OF CLIMB - feet/min 5000 400 CLIMB GRADIENT ANGLE OF CLIMB 1.5% 300
1.0% 200
0.5% 100 0160 180 200 220 240 260 280 FLIGHT PATH VELOCITY - knots (TAS) A7-13
Appendix 7 Figure A7-11 - Takeoff and Landing Crosswind Component Chart
TAKEOFF AND LANDING CROSSWIND COMPONENT
FLIGHT PATH
RUNWAY CENTERLINE 60 0° 10° 20' 50 30° WIND 40° - VELOC HEADWIND COMPONENT ~ KNOTS 50° ANGLE, DEGREES * 60° WIND 70° 80° 90° -10 100° = 180° 160 150° - 140°1 H· 130° • 120° • 110° -20 0 10 20 30 40 50 60 CROSSWIND COMPONENT ~ KNOTS A7-14
Appendix 8 Appendix 8. Conversion Factors Table LENGTH Multiply By To Obtain Centimetres 0.3937 Inches
0.03281 Feet .01 Meters Kilometres 3281 Feet
0.6214 Miles
0.5399 Nautical Miles 1093.6 Yards Meters 39.37 Inches
3.281 Feet
1.0936 Yards Statute Miles 5280 Feet
0.8690 Nautical Miles 1760 Yards Nautical Miles 6076.1 Feet
1.1508 Statute Miles WEIGHT Multiply By To Obtain Grams 0.03527 Ounces (advp)
0.002205 Pounds (advp) 1000 Milligrams
0.001 Kilograms Kilograms 2.205 Pounds (advp)
35.27 Ounces (advp) 1000 Grams Pounds (advp) 7000 Grains
16.0 Ounces
1.215 Pounds (troy) A8-1
Appendix 8 VOLUME Multiply By To Obtain Cubic Centimetres -310 Litres
0.0610 Cubic Inches Cubic Feet 28317 Cubic Centimeters 1728 Cubic Inches
0.03704 Cubic Yards
7.4805 Gallons (U.S.)
28.32 Litres Cubic Inches -34.329 x 10 Gallons (U.S.)
0.01732 Quarts (U.S.)
0.0164 Litres Cubic Meters 61023 Cubic Inches
35.31 Cubic Feet
264.17 Gallons (U.S.)
1.308 Cubic Yards Gallons Imperial 277.4 Cubic Inches
1.201 Gallons (U.S.)
4.546 Litres Gallons, U.S. 231 Cubic Inches
0.1337 Cubic Feet
3.785 Litres
0.8327 Imperial Gallons 128 Fluid Ounces Fluid Ounces 29.59 Cubic Centimeters
1.805 Cubic Inches Litres 61.02 Cubic Inches
0.2642 Gallons (U.S.)
1.057 Quarts (U.S.)
A8-2
Appendix 8 AREA Multiply By To Obtain Square Centimetres 0.1550 Square Inches
0.001076 Square Feet Square Feet 144 Square Inches
0.1111 Square Yards Square Inches 645.16 Square Millimeters Square Kilometres 0.3861 Square Statute Miles Square Meters 10.76 Square Feet
1.196 Square Yards Square Statute Miles 2.590 Square Kilometers A8-3
Appendix 8
VELOCITY Multiply By To Obtain Feet per Minute 0.01136 Miles Per Hour
0.01829 Kilometers Per Hour
0.5080 Centimeters Per Second
0.01667 Feet Per Second Feet Per Second 0.6818 Miles Per Hour
1.097 Kilometers Per Hour
30.48 Centimeters Per Second
0.3048 Meters Per Second
0.5921 Knots Knots 1.0 Nautical Miles Per Hour
1.6878 Feet Per Second
1.1508 Miles Per Hour
1.852 Kilometers Per hour
0.5148 Meters Per Second Meters Per Second 3.281 Feet Per Second
2.237 Miles Per Hour
3.600 Kilometers Per Hour Miles Per Hour 1.467 Feet Per Second
0.4470 Meters Per Second
1.609 Kilometers Per Hour
0.8690 Knots Radians Per Second 57.296 Degrees Per Second
0.1592 Revolutions Per Second
9.549 Revolutions Per Minute A8-4
Appendix 8
PRESSURE POWER Multiply By To Obtain Atmospheres 29.921 Inches of Mercury
14.696 Pounds Per Square Inch 2116.2 Pounds Per Square Foot Inches of Mercury 0.03342 Atmospheres
0.4912 Pounds Per Square Inch
70.727 Pounds Per Square Foot Inches of Water 0.00246 Atmospheres (at 4C) 0.07355 Inches of Mercury
0.03613 Pounds Per Square Inch
5.204 Pounds Per square Foot Pounds Per Square Inch 6.895 Kilo Pascals Multiply By To Obtain BTU Per Minute 12.96 Foot Pounds Per Second
0.02356 Horsepower Horsepower 33000 Foot Pounds Per Minute 550 Foot Pounds Per Second
0.7457 Kilowatts TEMPERATURE Degrees Kelvin = Degrees Celsius Plus 273.2 Degrees Rankine = Degrees Fahrenheit Plus 459.7 Multiply By To Obtain Fahrenheit 5/9 (F-32) Celsius Celsius 9/5 C+32 Fahrenheit A8-5
Appendix 8
ANGULAR DISPLACEMENT FORCE Multiply By To Obtain Degrees -21.745 x 10 Radians Radians 57.3 Degrees Multiply By To Obtain Pounds 4.448 Newtons A8-6
Appendix 9 Appendix 9. Airspeed Calibrations Introduction The airspeed and altimeter systems on an aircraft depend upon accurate measurements of ambient static pressure and total pitot pressure. Static and pitot pressures are sensed by the pitot static tube, which gives true readings in an undisturbed freestream when aligned with the flow streamlines; however, when attached to the aircraft, which generates a pressure when flying, the pitot and the static reading will be affected by the aircraft pressure field and the flow angularity. The errors, caused by the pressure field and by flow angularity are called position errors due to the sign and magnitude of the errors, which are a function of the position of the pitot-static probe on the aircraft. The position errors are a function of aircraft angle of attack and Mach number and are determined from flight test.
In this text, corrections are used rather than errors. Normally, errors are subtracted and corrections are added with the result that the position error corrections (PEC) are added to the aircraft pitot-static data to get the ambient conditions of static and pitot pressures. The ambient static pressure is defined as PSref and the ambient pitot pressure is defined as PPref. The position error correction of the static source PS is defined as P P PS Sref SA / C and PP the position error correction for the pitot pressure is defined as P P Pp Pr ef PA / C The total position error correction for a pitot static system to be used for an airspeed system is Pd where Pd PP PS General Discussion of the Various Flight Test Techniques Each of the flight test techniques (FTT's) that are described in this appendix have certain limitations and instrumentation accuracy criteria that must be considered prior to selecting a flight test technique.
The trailing bomb method only calibrates the aircraft static source. The bomb must be stable when flying below and behind the aircraft, any oscillations will make the reference static pressure invalid. At high speeds the bomb tends to rise up into the wake of the aircraft, which causes bomb oscillations; therefore, the trailing bomb has an upper airspeed limit. The trailing bomb is useful for most speeds up to approximately 200 knots and is particularly useful for helicopters. In addition, the trai ling bomb can also be used down to stall speeds. The trailing bomb deployed behind and below helicopters tends to keep the bomb and the attaching tube clear of the tail rotor; however, care must be taken when expanding the speed envelope.
A9-1
Appendix 9 The trailing cone method is capable of a much higher speed range than the trailing bomb and is a favorite method with the large aircraft manufacturers. The trailing cone method only calibrates the aircraft static pressure system.
The speed course method calibrates the airspeed indicator and considers the position error correction for both the static and pitot pressures. Use of the speed course data to calibrate the altimeter makes the assumption that the total position errors of both the pitot and the static sources are in the static source only. This assumption may not be correct. The main source of error in the ground course FTT is in timing since a stopwatch is used to record the time. Figure A9-1 shows the effect of aircraft airspeed on airspeed error with various length ground courses due to a 0.5 second timing error. Obviously, if the maximum error is limited to one knot, then the maximum speed for a three mile ground course would be about 120 knots. Essentially, the ground course method is suitable for slow moving aircraft.
The Global Positioning System (GPS) method is essentially the same as the speed course method except that the GPS unit replaces the stopwatch and, therefore, the timing errors are not an issue.
Satisfactory results have been obtained with a wide variety of inexpensive, handheld GPS units.
The best indication of the validity of data gathered using this method is the calculated wind.
Wind speed and direction are calculated as a by-product of the method. If the calculated wind is constant over a range of test points, then the calculated true airspeed can be considered valid. A significant advantage of this method is that it can be done at higher altitudes, allowing tests near stall speed. A disadvantage is that the relatively small speed error obtained will be the result of subtracting two larger numbers (actual true airspeed less the indicated airspeed correct to true).
At higher speeds, small percentage errors in true airspeed will have a larger impact on the position error.
A9-2
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i I o~~::::::::::]:_ __ ..,L ___ ,L_ __ _L ___ ~f ISO 100 Ampeed(kts) 11/16/2011 AC 23-8C Appendix 9 Figure A9-1 - Error Analysis of Ground Course Method The pace aircraft technique for pitot static calibration is often the initial calibration method for the first flight of a new aircraft or the first flights of extensively modified aircraft. The problem with the pace aircraft method is the accuracy of reading both the altimeter and airspeed indicators in both aircraft simultaneously, and any errors in the pace aircraft are transferred to the test aircraft.
The pitot-static boom method is a standard for small aircraft; however, prior to use, it must be established that the boom static source is outside the pressure field of the aircraft and the pitot tube is unaffected by the flow angularity at the boom.
The tower fly-by method only calibrates the aircraft static source and, if the data are used to calibrate the airspeed systems, the assumption is that the pitot has no errors. Accuracy problems exist with the tower fly-by method if altimeters are used in the tower and in the aircraft. The reading accuracy of an altimeter is generally + 10 feet; therefore, the combined error of both altimeters could be + 20 feet, which is very close to the FAR/JAR limits of + 30 feet per 100 knots. The use of sensitive pressure transducers in the tower and the aircraft considerably improve the reading accuracy. An additional improvement in accuracy can be obtained by taking aircraft ground block data at the base of the fly-by tower, i.e., record the altimeter and temperature and compare the tower data taking into consideration the height o the tower.
The tower fly-by method is also useful as measuring the recovery factor of temperature measuring systems. The serious limitations of the tower fly-by method are: the requirement for an instrumented tower and a fly-by line, the hazard of flying near the stall speeds and the Mach limits of the aircraft close to the ground and the time consuming procedure of one data point per aircraft circuit.
A summary of the speed ranges for various PEC flight test techniques is shown in Figure A9-2.
A9-3
-100 0 100 200 300 V, (kts) 1100 Trailing Static Bomb Appendix 9 Figure A9-2 - Summary of PEC Test Methods
1. Trailing Bomb or Cone Method. A trailing bomb or cone, as depicted in Figure A9-3 is used to measure the static pressure of the ambient air about the aircraft. The trailing bomb is sufficiently behind and below the aircraft and the trailing cone is sufficiently far behind the aircraft to be unaffected by the pressure field around the aircraft and can, therefore, be referred to as the reference static pressure (PSref).
Figure A9-3 - Sketches of Trailing Static Bomb and the Trailing Static Cone (not to scale) A trailing bomb or cone can be used to calibrate the aircraft static source or to determine the Position Error Correction (PEC's) for the altimeter. The use of the reference static sources to calibrate the airspeed systems assumes that the errors in the total head (pitot tube) are zero. The reference static sources could be connected to the altimeter, which would read the pressure altitude of the aircraft. The difference between the reference altitude from the trailing cone or bomb and the aircraft altitude, both corrected for instrument errors, would be the position error correction for the altimeter H pec for a particular aircraft configuration and speed.
A9-4