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A Theoretical Investigation of Longitudinal Stability of Airplanes with Free Controls Including Effect of Friction in Control System

Description: "The relation between the elevator hinge moment parameters and the control forces for changes in forward speed and in maneuvers is shown for several values of static stability and elevator mass balance. The stability of the short period oscillations is shown as a series of boundaries giving the limits of the stable regions in terms of the elevator hinge moment parameters. The effects of static stability, elevator moment of inertia, elevator mass unbalance, and airplane density are also consider… more
Date: 1944
Creator: Greenberg, Harry & Sternfield, Leonard
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Determination of lateral-stability derivatives and transfer-function coefficients from frequency-response data for lateral motions

Description: A method is presented for determining the lateral-stability derivatives, transfer-function coefficients, and the modes for lateral motion from frequency-response data for a rigid aircraft. The method is based on the application of the vector technique to the equations of lateral motion, so that the three equations of lateral motion can be separated into six equations. The method of least squares is then applied to the data for each of these equations to yield the coefficients of the equations o… more
Date: 1955
Creator: Donegan, James J.; Robinson, Samuel W., Jr. & Gates, Ordway B., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A flight evaluation of the longitudinal stability characteristics associated with the pitch-up of a swept-wing airplane in maneuvering flight at transonic speeds

Description: This report presents the results of flight measurements of longitudinal stability and control characteristics made on a swept-wing jet aircraft to determine the origin of the pitch-up encountered in maneuvering flight at transonic speeds. For this purpose measurements were made of elevator angle, tail angle of attack, and wing-fuselage pitching moments (obtained from measurements of the balancing tail loads).
Date: September 12, 1951
Creator: Anderson, Seth B. & Bray, Richard S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Charts for estimating tail-rotor contribution to helicopter directional stability and control in low-speed flight

Description: "Theoretically derived charts and equations are presented by which tail-rotor design studies of directional trim and control response at low forward speed can be conveniently made. The charts can also be used to obtain the main-rotor stability derivatives of thrust with respect to collective pitch and angle of attack at low forward speeds. The use of the charts and equations for tail-rotor design studies is illustrated. Comparisons between theoretical and experimental results are presented. The… more
Date: October 27, 1953
Creator: Amer, Kenneth B. & Gessow, Alfred
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A wind-tunnel test technique for measuring the dynamic rotary stability derivatives at subsonic and supersonic speeds

Description: "A method is described for measuring the dynamic stability derivatives of a model airplane in a wind tunnel. The characteristic features of this system are that single-degree-of-freedom oscillations were used to obtain combinations of rolling, yawing and pitching motions; that the oscillations were excited and controlled by velocity feedback which permitted operation under conditions unfavorable for more conventional types of oscillatory testing; and that data processing was greatly simplified … more
Date: September 20, 1954
Creator: Beam, Benjamin H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Studies of the speed stability of a tandem helicopter in forward flight

Description: Flight-test measurements, related analytical studies, and corresponding pilots' opinions of the speed stability of tandem-rotor helicopter are presented. An undesirable instability, evidenced by rearward stick motion with increasing forward speed at constant power, is indicated to be caused by variations with speed of the front-rotor downwash at the rear rotor. An analytical expression for predicting changes in speed stability caused by changes in rotor geometry is derived and constants for use… more
Date: June 4, 1953
Creator: Tapscott, Robert J. & Amer, Kenneth B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

High-Speed Tests of a Model Twin-Engine Low-Wing Transport Airplane

Description: Report presents the results of force tests made of a 1/8-scale model of a twin-engine low-wing transport airplane in the NACA 8-foot high-speed tunnel to investigate compressibility and interference effects of speeds up to 450 miles per hour. In addition to tests of the standard arrangement of the model, tests were made with several modifications designed to reduce the drag and to increase the critical speed.
Date: 1942
Creator: Becker, John V. & Leonard, Lloyd H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Requirements for Satisfactory Flying Qualities of Airplanes

Description: Report discusses the results of an analysis of available data to determine what measured characteristics are significant in defining satisfactory flying qualities, what characteristics are reasonable to require of an airplane, and what influence the various design features have on the observed flying qualities.
Date: March 24, 1941
Creator: Gilruth, R. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Theoretical Investigation of the Lateral Oscillations of an Airplane With Free Rudder With Special Reference to the Effect of Friction

Description: "Charts showing the variation in dynamic stability with the rudder hinge-moment characteristics are presented. A stabilizing rudder floating tendency combined with a high degree of aerodynamic balance is shown to lead to oscillations of increasing amplitude. This dynamic instability is increased by viscous-friction in the rudder control system" (p. 147).
Date: March 4, 1943
Creator: Greenberg, Harry & Sternfield, Leonard
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind-tunnel procedure for determination of critical stability and control characteristics of airplanes

Description: This report outlines the flight conditions that are usually critical in determining the design of components of an airplane which affect its stability and control characteristics. The wind-tunnel tests necessary to determine the pertinent data for these conditions are indicated, and the methods of computation used to translate these data into characteristics which define the flying qualities of the airplane are illustrated.
Date: 1944
Creator: Goett, Harry J.; Jackson, Roy P. & Belsley, Steven E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Theoretical Investigation of the Rolling Oscillations of an Airplane With Ailerons Free

Description: "An analysis is made of the stability of an airplane with ailerons free, with particular attention to the motions when the ailerons have a tendency to float against the wind. The present analysis supersedes the aileron investigation contained in NACA Technical Report no. 709. The equations of motion are first written to include yawing and sideslipping, and it is demonstrated that the principal effects of freeing the ailerons can be determined without regard to these motions" (p. 255).
Date: November 19, 1943
Creator: Cohen, Doris
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Principles of Moment Distribution Applied to Stability of Structures Composed of Bars or Plates

Description: "The principles of the cross method of moment distribution, which have previously been applied to the stability of structures composed of bars under axial load, are applied to the stability of structures composed of long plates under longitudinal load. A brief theoretical treatment of the subject, as applied to structures composed of either bars or plates, is included, together with an illustrative example for each of these two types of structure. An appendix presents the derivation of the form… more
Date: 1945
Creator: Lundquist, Eugene E.; Stowell, Elbridge Z. & Schuette, Evan H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Prediction of the Effects of Propeller Operation on the Static Longitudinal Stability of Single-Engine Tractor Monoplanes with Flaps Retracted

Description: "The effects of propeller operation on the static longitudinal stability of single-engine tractor monoplanes are analyzed, and a simple method is presented for computing power-on pitching-moment curves for flap-retracted flight conditions. The methods evolved are based on the results of powered-model wind-tunnel investigations of 28 model configurations. Correlation curves are presented from which the effects of power on the downwash over the tail and the stabilizer effectiveness can be rapidly… more
Date: July 13, 1948
Creator: Weil, Joseph & Sleeman, William C., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A simplified method for the determination and analysis of the neutral-lateral-oscillatory-stability boundary

Description: A necessary condition for neutral oscillatory stability is that Routh's discriminant r, formed from the coefficients of the stability equation, is equal to zero. Computations obtained from rsub1=0 and d=0 show very good agreement with the results calculated by the expression for r=0. The nature of the modes of motion as a function of the directional-stability derivative and the effective-dihedral derivative is discussed in detail.
Date: 1949
Creator: Sternfield, Leonard & Gates, Ordway B., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The Longitudinal Stability of Elastic Swept Wings at Supersonic Speed

Description: "The longitudinal stability characteristics of elastic swept wings of high aspect ratio experiencing bending and torsional deformations are calculated for supersonic speed by the application of linearized lifting-surface theory. A parabolic wing deflection curve is assumed and the analysis is simplified by a number of structural approximations. The method is thereby limited in application to wings of high aspect ratio for which the root effects are small" (p. 1).
Date: December 3, 1948
Creator: Frick, C. W. & Chubb, R. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Theoretical Stability Derivatives of Thin Sweptback Wings Tapered to a Point with Sweptback or Sweptforward Trailing Edges for a Limited Range of Supersonic Speeds

Description: "The stability derivatives valid for a limited range of supersonic speeds are presented for a series of sweptback wings tapered to a point with sweptback or sweptforward trailing edges. These wings were derived by modifying the trailing edge of a basic triangular wing so that it coincided with lines drawn from the wing tips to the wing axis of symmetry. The stability derivatives were formulated by using the pressure distributions previously obtained for the basic triangular wing for angle of at… more
Date: September 23, 1948
Creator: Malvestuto, Frank S., Jr. & Margolis, Kenneth
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Investigation at low speeds of the effect of aspect ratio and sweep on rolling stability derivatives of untapered wings

Description: A low-scale wind-tunnel investigation was conducted in rolling flow to determine the effects of aspect ratio and sweep (when varied independently) on the rolling stability derivatives for a series of untapered wings. The rolling-flow equipment of the Langley stability tunnel was used for the tests. The data of the investigation have been used to develop a method of accounting for the effects of the drag on the yawing moment due to rolling throughout the lift range.
Date: January 19, 1949
Creator: Goodman, Alex & Fisher, Lewis R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effect of afterbody length and keel angle on minimum depth of step for landing stability and on take-off stability of a flying boat

Description: From Summary: "Tests were made to fill partly the need for information on the effect of afterbody dimensions on the hydrodynamic stability of a flying boat in smooth water. The dimensions investigated were depth of step, angle of afterbody keel, and length of afterbody. An analysis of the data showed that as either the afterbody length or keel angle was increased an accompanying increase in depth of step was required in order to maintain adequate landing stability."
Date: November 13, 1947
Creator: Olson, Roland E. & Land, Norman S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Appreciation and Prediction of Flying Qualities

Description: "The material given in this report summarizes some of the results of recent research that will aid the designers of an airplane in selecting or modifying a configuration to provide satisfactory stability and control characteristics. The requirements of the NACA for satisfactory flying qualities, which specify the important stability and control characteristics of an airplane from the pilot's standpoint, are used as the main topics of the report. A discussion is given of the reasons for the requ… more
Date: April 12, 1948
Creator: Phillips, William H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effect of centrifugal force on the elastic curve of a vibrating cantilever beam

Description: From Summary: "A study was made to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. The results of a mathematical analysis are presented together with experimental results obtained by means of stroboscopic photographs and strain gages. The theoretical analysis was confined to uniform cantilever beams; the experimental work was extended to include a tapered cantilever beam to simulate an aircraft propeller blade. Calculations were made on nondime… more
Date: 1948
Creator: Simpkinson, Scott H.; Eatherton, Laurel J. & Millenson, Morton B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Frequency-Response Method for Determination of Dynamic Stability Characteristics of Airplanes With Automatic Controls

Description: "A frequency-response method for determining the critical control-gearing and hunting oscillations of airplanes with automatic pilots is presented. The method is graphical and has several advantages over the standard numerical procedure based on Routh's discriminant. The chief advantage of the method is that direct use can be made of the measured response characteristics of the automatic pilot. This feature is especially useful in determining the existence, amplitude, and frequency of the hunti… more
Date: 1947
Creator: Greenberg, Harry
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The problem of longitudinal stability and control at high speeds

Description: In high-speed dives many airplanes exhibit a dangerous tendency to continue diving in spite of the application of large control forces. Wind-tunnel tests have confirmed that these difficulties are not peculiar to any particular configuration, so that the problem is of interest to all designers of high-speed airplanes. The purpose of this report is to acquaint designers with the cause of difficulties and with the means now known for their alleviation.
Date: 1943
Creator: Hood, Manley J. & Allen, H. Julian
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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