Showing papers on "Wing root published in 1977"

Multi-winged lifting body aircraft

Abstract: Fore mounted aft swept and aft mounted forward swept wings extend from either side of a lifting body fuselage. Each lateral pair of the wings is joined at the tops by a wing tip vortex translating device to induce translation of the tip generated vortices along the trailing edge of the aft wings. End plates extend rearwardly from the maximum chord thickness of the fuselage to increase the effective lift of the fuselage. An elevator, mounted intermediate the rear top of the end plates, provides pitch control and structurally augments the wing root and fuselage junction of the aft mounted wings. A power plant disposed at the rear of the fuselage provides thrust and also dissipates, as useful thrust, the wing tip vortices translated from the tips to the power plant along the trailing edges of the aft wings.

C-5A Active Load Alleviation System

Abstract: Several forms of wing load reduction systems have been investigated for use on the C-5A C-5A for the purpose of reducing static loads and/or improving the fatigue life of the wing. A passive system presently is used on the C-5A fleet to provide reduced static wing bending moments for improved payload/gross weight capabilities and to improve wing fatigue life through reduced mean stresses. A fully active maneuver and gust load reduction system has been developed and flight tested and is being incorporated on the C-5A force at present. This system was developed for the specific purpose of providing a significant wing fatigue life improvement through reduction of maneuver and gust-induced incremental wing bending moments. This paper reviews the evolution of the present load-alleviation system (termed ALDCS for active lift distribution control system) and presents a brief description of the system and a simplified functional block diagram. Comparisons of analytical and flight-test-measured maneuver and continuous turbulence loads are shown. The effects of load changes on fatigue damage rate predictions are discussed, with particular emphasis on the implications of multiple-load component changes, i.e., reduced bending moments and increased torsional moments.

Effect' of winglets on a first-generation jet transport wing

Abstract: SUMMARY OF RESULTS A wind-tunnel investigation of winglets mounted on the tip of a 0.07-scale KC-135A jet transport model wing has been conducted. Configurations with an upper winglet only and with upper and lower winglets are compared with a simple wing-tip extension which is designed to produce the same increase in bending moment at the wing root (at a lg load factor) as do the winglets. Data are pre- sented at four high subsonic Mach numbers and one low subsonic Mach number, and indicate the following conclusions: 1. Both winglet configurations reduce induced drag by approximately 20 per- cent at design cruise conditions. The tip extension reduces induced drag by about 10 percent at design conditions. 2. At cruise conditions winglets produce improvements in lift-drag ratio of about 9 percent. improvement in lift-drag ratio. At the same conditions the tip extension produces a 4-percent 3. The negative increments in pitching-moment coefficient due to the wing- lets are less than those produced by the tip extension. 4.

Real-time testing of titanium sheet and extrusion coupon specimens subjected to Mach 2.7 supersonic cruise aircraft wing stresses and temperatures

Abstract: The accuracy of three accelerated flight-by-flight test methods for material selection, and fatigue substantiation of supersonic cruise aircraft structure was studied. The real time stresses and temperatures applied to the specimens were representative of the service conditions in the lower surface of a Mach 2.7 supersonic cruise aircraft wing root structure. Each real time flight lasted about 65 minutes, including about one hour at (500 F) in the cruise condition. Center notched coupon specimens from six titanium materials were tested: mill-annealed, duplex-annealed, and triplex-annealed Ti-8Al-1Mo-1V sheets; mill-annealed Ti-8Al-1Mo-1V extrusion; mill-annealed Ti-6Al-4V sheet; and solution-treated and aged Ti-6Al-4V extrusion. For duplex-annealed Ti-8Al-1Mo-1V sheet, specimens with single spotweld were also tested. The test results were studied in conjunction with other related data from the literature for: material selection, structural fabrication, fatigue resistance of supersonic cruise aircraft structure, and fatigue test acceleration procedures for supersonic cruise aircraft.

Lateral equilibrium of asymmetrical swept wings - Aileron control vs geometric twist

Abstract: A static aeroelastic phenomenon unique to an aircraft with asymmetrically swept wings is discussed. A simple formula is derived from the analysis of a highly idealized model. The validity of this formula is examined through the use of a more sophisticated numerical analysis. Among the results of this analysis are the following: aileron settings of a few degrees are sufficient to trim such aircraft in roll-for-g-flight; the use of built-in twist in the form of initial negative dihedral provides an efficient alternative to aileron trim; if the wing is elastically tailored in a proper fashion, it may be possible to design a wing whose elastic deformation under airloads provides a form of self-trim in roll at the cruise q of the aircraft.

Strain Gage Calibration of a Complex Wing

Abstract: Modern complex structural arrangements have complicated the task of measuring flight loads with calibrated strain gages. This paper examines the use of a relatively simple structural model to characterize the load responses of strain gages located on various spars of a delta wing. Strains measured during a laboratory load calibration of a wing structure are compared with calculations obtained from a simplified NASA structural analysis (NASTRAN) model. Calculated and measured influence coefficient plots that show the shear, bending, and torsion characteristics of typical strain-gage bridges are presented. Typical influence coefficient plots are given for several load equations to illustrate the derivation of the equations from the component strain-gage bridges. A relatively simple structural model was found to be effective in predicting the general nature of strain distributions and influence coefficient plots. The analytical processes are shown to be useful in obtaining a good load calibration. The analytical processes cannot, however, be used in lieu of an actual load calibration of an aircraft wing.