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in creator/contributor: "Letko, William"  
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Experimental Investigation at Low Speed of the Effects of Wing Position on the Static Stability of Models Having Fuselages of Various Cross Section and Unswept and 45 Degrees Sweptback Surfaces

Description: Note presenting an investigation to determine the effects of wing position on the low-speed static longitudinal and static lateral stability of airplane models with fuselages of square and rectangular cross sections and unswept and 45 degree sweptback surfaces. The results of the investigation indicated that at low angles of attack, the complete unswept models with the wing in the high position were more stable or least longitudinally unstable. The results also showed that wing-fuselage interfe… more
Date: November 1956
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Low-Speed Experimental Study of the Directional Characteristics of a Sharp-Nosed Fuselage Through a Large Angle-of-Attack Range at Zero Angle of Sideslip

Description: Static yawing moments and some instantaneous yawing moments are presented through a range of angle of attack at zero sideslip angle for a plain fuselage model having a sharp conical nose and for the fuselage with several nose modifications, one of which consisted of a ring located at different stations along the nose. Some circumferential pressure measurements at one station on the body at several angles of attack are also presented.
Date: March 1953
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Investigation of the Fuselage Interference on a Pitot-Static Tube Extending Forward From the Nose of the Fuselage

Description: Note presenting an investigation to determine the interference effects of three fuselages on the readings of a pitot-static tube extending various distances forward from the noses of the fuselages. The fuselages investigated were bodies of revolution with maximum diameters equal to 12 percent of the fuselage length and with circular-nose, elliptical-nose, and pointed-nose shapes. Results regarding interference at zero angle of attack, effect of free-stream impact pressure, and effect of tube di… more
Date: December 1947
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind Tunnel Investigation at Low Speed of Aerodynamic Characteristics of Army Chemical Corps Model E-112 Bomblets with Span Chord Ratio of 2 - 1

Description: "An experimental investigation has been made in the Langley stability tunnel to determine the aerodynamic characteristics of the Army Chemical Corps model E-112 bomblets with span-chord ratio of 2:1. A detailed analysis has not been made; however, the results showed that all the models were spirally unstable and that a large gap between the model tips and end plates tended to reduce the instability" (p. 1).
Date: December 26, 1956
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Low-Speed Experimental Study of the Directional Characteristics of a Sharp-Nosed Fuselage Through a Large Angle-of-Attack Range at Zero Angle of Sideslip

Description: Report presenting an investigation to determine the directional characteristics of a sharp-nosed fuselage through a large angle-of-attack range at zero angle of sideslip. The fuselage was found to experience a large increase in yawing moment as the angle of attack increases. The results also indicated that a ring or other roughness used on the nose caused a large decrease in the yawing moment obtained at high angles of attack.
Date: November 19, 1952
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Experimental Determination at Subsonic Speeds of the Oscillatory and Static Lateral Stability Derivatives of a Series of Delta Wings With Leading-Edge Sweep From 30 to 86.5 Degrees

Description: Memorandum presenting a determination of the static lateral stability of six delta wings at subsonic speeds. In addition, two of the wings with 82.5 degree and 75 degree sweep of the leading edge were oscillated in yaw about the 50-percent point of the root chord in order to determine the effects of frequency and amplitude on the combination lateral stability derivatives resulting from the motion. Results regarding the static characteristics and oscillatory characteristics are provided.
Date: April 12, 1957
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind-Tunnel Investigation of Split Trailing-Edge Lift and Trim Flaps on a Tapered Wing With 23 Degree Sweepback

Description: Note presenting the results of force tests and pressure-distribution measurements from a wind-tunnel investigation to determine the effects of size and hinge location of lift and trim flaps on the lift and pitching moment characteristics of a semispan tapered wing with 23 degrees sweepback of the quarter-chord line. The flaps were tested with different chords, spans, and trim flaps. The results indicated that the static longitudinal stability of the sweptback wing, as indicated by the slope of … more
Date: July 1947
Creator: Letko, William & Feigenbaum, David
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Correlation of Two Experimental Methods of Determining the Rolling Characteristics of Unswept Wings

Description: Note presenting the rolling moments of one tapered wing and two geometrically similar wings in rolling flow with the wing stationary and in straight flow with forced rotation of the wing to obtain a correlation between the two methods of testing and to determine the rolling characteristics of the wings. The results showed that for unswept wings the rolling characteristics obtained by rotation of the air agreed with those obtained by forced rotation of the wing.
Date: May 1947
Creator: MacLachlan, Robert & Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Preliminary Wind-Tunnel Investigation at Low Speed of Stability and Control Characteristics of Swept Back Wings

Description: Note presenting tests conducted on untapered constant-span wings of 0, 30, 45, and 60 degrees sweepback. The purpose of the tests was to investigate the effect of sweepback on stability and control characteristics. The data showed large changes in longitudinal stability at moderate lift coefficients for the 45 and 60 degree sweptback wings.
Date: April 1946
Creator: Letko, William & Goodman, Alex
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effects of frequency and amplitude on the yawing derivatives of triangular, swept, and unswept wings and of a triangular-wing-fuselage combination with and without a triangular tail performing sinusoidal yawing oscillations

Description: Report presenting an investigation to determine the effects of frequency and amplitude on the yawing derivatives of triangular, swept, and unswept wings. Results regarding the damping in yaw, rolling moment due to yawing, acceleration derivatives, and comparison of yawing and acceleration derivatives with combined derivatives for wings alone are provided for configurations of the wing alone and wing-body combinations.
Date: September 1958
Creator: Letko, William & Fletcher, Herman S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effect of an unswept wing on the contribution of unswept-tail configuration to the low-speed static and rolling-stability derivatives of a midwing airplane model

Description: Report presenting an investigation conducted in the stability tunnel to determine the effect of an unswept wing on the contribution of unswept-tail configurations to the low-speed-static- and rolling-stability derivatives of a midwing airplane model. The results show that there tend to be only small differences in the tail contributions to the static-lateral-stability derivatives for configurations with the wing on and wing off.
Date: August 1950
Creator: Letko, William & Riley, Donald R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effect of taper ratio on low-speed static and yawing stability derivatives of 45 degree sweptback wings with aspect ratio of 2.61

Description: Report presenting a low-speed wind-tunnel investigation to determine the effect of taper ratio on the static and yawing stability derivatives of three tapered wings with a constant sweepback of 45 degrees at the quarter-chord line and with an aspect ratio of 2.61 but different taper ratios. Results regarding the characteristics in straight flow and yawing flow are provided.
Date: July 1948
Creator: Letko, William & Cowan, John W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind Tunnel Investigation at Low Speed of the Aerodynamic Characteristics of the Army Chemical Corps Model E112 Bomblets

Description: Report discussing an experimental investigation to determine the aerodynamic characteristics of the Army Chemical Corps model E112 bomblets. From Summary: "A detailed analysis has not been made; however, the results showed that a gap between model tips and the end plates or increasing the end-plate size for a solid model could result in a spirally stable configuration." A large amount of data collected from testing and photographs of the model are provided.
Date: November 4, 1955
Creator: Letko, William & Williams, James L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effect of airfoil profile of symmetrical sections on the low-speed static-stability and yawing derivatives of 45 degrees sweptback wing models of aspect ratio 2.61

Description: Report presenting an investigation in the stability tunnel to determine the effect of airfoil profile on symmetrical sections on the static- and yawing-stability derivatives of three untapered wings of 45 degrees sweepback. All of the wings had an aspect ratio of 2.61. Results regarding the characteristics in straight flow, yawing flow, and drag index are provided.
Date: November 9, 1948
Creator: Letko, William & Jaquet, Byron M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Experimental investigation at low speed of effects of fuselage cross section on static longitudinal and lateral stability characteristics of models having 0 and 45 degrees sweptback surfaces

Description: Report presenting an experimental investigation at low speed to determine the effects of fuselage cross section on the static longitudinal and lateral stability characteristics of midwing airplane models with 0 and 45 degrees sweptback surfaces. The results indicated that the main effect of fuselage cross section on the longitudinal and directional stability characteristics of the modles at low angles of attack are caused by the direction contributions of the fuselage.
Date: December 1955
Creator: Letko, William & Williams, James L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effect of Sweepback on the Low-Speed Static and Rolling Stability Derivatives of Thin Tapered Wings of Aspect Ratio 4

Description: Report discussing an investigation to determine the effect of sweepback on the static and rolling stability derivatives of a series of wings with a taper ratio of 0.6 and an aspect ratio of 4. The influence on the straight-flow characteristics, rolling-flow characteristics, and aileron characteristics are provided.
Date: August 9, 1949
Creator: Letko, William & Wolhart, Walter D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Theoretical Investigation at Subsonic Speeds of the Flow Ahead of a Slender Inclined Parabolic-Arc Body of Revolution and Correlation With Experimental Data Obtained at Low Speeds

Description: Report presenting charts which permit the rapid estimation of deviations from free-stream values of static pressure, angle of attack, and angle of sideslip so that ideal positions for orifices and vanes for measuring these qualities can be selected. The effects of thickness and angle of attack are considered in greater detail.
Date: July 1954
Creator: Letko, William & Danforth, Edward C. B., III
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind-tunnel investigation of a number of total-pressure tubes at high angles of attack: Subsonic speeds

Description: Report presenting an investigation of the possibility of designing a fixed total-pressure tube which will remain insensitive to inclination of the air stream over a wide range of angle of attack through subsonic and supersonic speed ranges.
Date: April 1951
Creator: Gracey, William; Letko, William & Russell, Walter R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind-Tunnel Investigation of the Low-Speed Static Stability and Control Characteristics of a Model of the Bell MX-776 (RASCAL) in Combined Angle of Attack and Sideslip

Description: "An investigation has been made in the Langley stability tunnel to determine the low-speed static stability and control characteristics of a model of the Bell MX-776. The results show the model to be longitudinally unstable in the angle-of-attack range around zero angle of attack and to become stable at moderate angles of attack. The results of the present investigation agree reasonably well with results obtained in other facilities at low speed" (p. 1).
Date: 1952
Creator: Letko, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind-tunnel investigation of six shielded total-pressure tubes at high angles of attack: Subsonic speeds

Description: Report presenting a study of the effect of inclination of the air stream on the measured pressures of six shielded total-pressure tubes for a range of angles of attack. The tests were conducted over a range of Mach numbers. Results indicated that the shape of the venturi entry has a pronounced effect on the range of angles of attack over which the tubes remain insensitive to inclination of the air stream.
Date: November 1951
Creator: Russell, Walter R.; Gracey, William; Letko, William & Fournier, Paul G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wind-tunnel investigation at low speed of the aerodynamic characteristics of the Army Chemical Corps model E112 bomblets

Description: "An experimental investigation has been made n the Langley stability tunnel to determine the aerodynamic characteristics of the Army Chemical Corps model E112 bomblets. A detailed analysis has not been made; however, the results showed that a gap between model tips and the end plates or increasing the end-plate size for a solid model could result in a spirally stable configuration" (p. 1).
Date: November 4, 1955
Creator: Letko, William & Williams, James L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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