Flight Test Engineering Handbook

Herrington, Russel M.; Shoemacher, Paul E.; Bartlett, E. P.; Dunlap, Everett W.

doi:10.21236/ad0636392

Cited by 19 publications

(5 citation statements)

References 1 publication

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“…The set of constants from reference [11][12][13][14][15][16][17][18][19][20][21] 9 produced the closest agreement between equations (17) and (19). These values were the ones "most used" for orbital calculations.…”

Section: Geophysical Constantsmentioning

confidence: 99%

Theory of the Measurement and Standardization of In-Flight Performance of Aircraft

Dunlap¹,

Porter²

1971

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Section: Geophysical Constantsmentioning

confidence: 99%

Theory of the Measurement and Standardization of In-Flight Performance of Aircraft

Dunlap¹,

Porter²

1971

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“…= nozzle area, ft 2 CD = drag coefficient, dimensionless C g = nozzle coefficient, dimensionless CL = lift coefficient, dimensionless D = drag, Ib F e = inlet momentum (ram drag), Ib F ex = excess thrust, Ib F g = gross thrust, Ib H = geopotential altitude, ft I( ) = interval estimate of ( ) Ki = 6.87535 X 10 ~6, 1 afterburning turbojet engine which show how inaccuracies in variables measured in flight are reflected in an aircraft's performance parameters. With these equations the sensitivity of performance parameters to measured variables can be found.…”

Section: Asmentioning

confidence: 99%

Propagation of error in the calculation of airplane thrust and drag

Dunlap

1969

Journal of Aircraft

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Knowledge of an airplane's drag polar is needed to establish the performance characteristics of the airplane. In-flight measurements are frequently made during the course of test programs to define drag polars. Inaccuracies in the measured variables can contribute to significant uncertainties in computed lift and drag coefficients. To gain an appreciation of the magnitude of these uncertainties, equations have been derived for an aircraft powered by a nonafterburning turbojet engine which express the inaccuracies in lift and drag coefficients in terms of inaccuracies in measured variables. As a by-product, the variables that are the source of the larger inaccuracies in the drag polar can be found and the need for improved instrumentation identified. Sample calculations were made using data from the Air Force performance tests on the A-37A, and inaccuracies in its drag polar, as well as in the intermediate answers (gross thrust, inlet momentum, and drag), are shown graphically. These calculations indicate that the most critical measurements are of turbine discharge pressure and vane alignment (to orient axes of accelerometers used to compute excess thrust); degradation of computed drag from errors in these variables is most pronounced at high lift coefficients. Nomenclature AS= nozzle area, ft 2 CD = drag coefficient, dimensionless C g = nozzle coefficient, dimensionless CL = lift coefficient, dimensionless D = drag, Ib F e = inlet momentum (ram drag), Ib F ex = excess thrust, Ib F g = gross thrust, Ib H = geopotential altitude, ft I( ) = interval estimate of ( ) Ki = 6.87535 X 10 ~6, 1/geopotential ft #2 = 5.2561 K s = 17058.8 psf K 4 = 0.43034 ft 2 /lb K 5 = 661.48 knots K a = percentage point M = Mach number, dimensionless n x = load factor along wind x-axis, dimensionless n z = load factor along wind z-axis, dimensionless P a = ambient pressure, m . Hg Pt& = turbine discharge pressure,m. Hg S = wing area, ft 2 T = ambient temperature, °K * Chief, Aircraft Research Section. V c = calibrated airspeed, knots V'i = true airspeed, knots &V C = compressibility correction V c = V c -f &V C) knots w a = airflow, Ib/sec W = airplane gross weight, Ib e -misalignment angle, rad Psi = air density at sea level, slugs/ft 3 o-= standard deviation, air density ratio cr 2 = variance Superscript * = nominal value

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“…Most of these methods can be traced back to Lush 1 and have been updated by others. [2][3][4][5][6] The so-called Lush equations were used to correct takeoff distance for the effects of non-standard ambient air temperature, pressure altitude, aircraft gross weight, and engine thrust. The equations used the "ratio" method of standardization 7 and worked by scaling the test-day measured takeoff distance using analytically-derived correction ratios with empirically-derived powers, as shown in equation 1 for a turboprop aircraft.…”

Section: Introductionmentioning

confidence: 99%

A Method of Standardizing Takeoff Performance Data Using Modeling and Simulation

Orleans

Woolf

Afb³

2012

28th Aerodynamic Measurement Technology, Ground Testing, and Flight Testing Conference

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Existing methods of correcting takeoff distance data to reference conditions rely on analytical or empirical equations that are limited to small incremental corrections for a small number of factors. An alternate method of standardizing takeoff performance data is presented here that uses modeling and simulation to correct for the effects of non-standard ambient air temperature, pressure altitude, wind, runway slope, aircraft gross weight, pilot technique, and numerous other factors. The method uses a two-degree-of-freedom takeoff simulation to calculate corrections to the test-day measured distances and airspeeds at rotation, liftoff, and 50 feet above ground level. Since the simulation is physics-based, it can be used to make large corrections and extrapolations over the full range of conditions for which its component models are valid. The simulation uses models of the aerodynamic, propulsive, and rolling resistance forces that are validated or updated based on flight test results. Two methods of modeling pilot rotation and pitch attitude capture techniques are implemented. Application of the modeling and simulation method is illustrated using flight test data from a four-engine turboprop tactical transport aircraft. Nomenclatureforce coefficient along the flight path [n/d] C y = force coefficient normal to the flight path [n/d] F E = propulsive drag [lb] F G = gross thrust [lb] g = acceleration due to gravity [32.174 ft/sec 2 ] h = geometric altitude [ft] HP = propeller shaft horsepower [hp] i T = thrust line incidence angle [deg] N = propeller speed [rpm] q = incompressible dynamic pressure [lb/ft 2 ] S = reference (wing) area [ft 2 ] S g,std = standardized ground roll distance [ft] S g,test = test-day measured ground roll distance, corrected for wind effects [ft] S g,test,w = test-day measured ground roll distance, uncorrected for wind effects [ft] S level = ground roll distance, corrected to zero-slope runway [ft] S slope = test-day measured ground roll distance, uncorrected for runway slope effects [ft] S std = standardized distance [ft] S′ std = reference-day predicted distance [ft] S test = test-day measured distance [ft] S′ test = test-day predicted distance [ft] t = time [sec] TOLAND = takeoff and landing simulation 1 Aerospace Engineer, 773TS/ENFB, Air Force Flight Test Center. American Institute of Aeronautics and Astronautics 2 V to = ground speed at takeoff [ft/sec] V w = wind speed [ft/sec] W = aircraft gross weight [lb]  = angle of attack [deg]  = density ratio [n/d]  = flight path angle [deg]  slope = runway slope [deg]  = rolling friction coefficient [n/d] std = standard or reference conditions test = test-day measured conditions

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Flight Test Engineering Handbook

Cited by 19 publications

References 1 publication

Theory of the Measurement and Standardization of In-Flight Performance of Aircraft

Theory of the Measurement and Standardization of In-Flight Performance of Aircraft

Propagation of error in the calculation of airplane thrust and drag

A Method of Standardizing Takeoff Performance Data Using Modeling and Simulation

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