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Results for “PROPELLER SLIPSTREAM”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1938

Wind-tunnel Tests of a 2-engine Airplane Model as a Preliminary Study of Flight Conditions Arising on the Failure of the Engine

Wind tunnel tests of a 15-foot-span model of a two-engine low wing transport airplane were made as a preliminary study of the emergency arising from the failure of one engine in flight. Two methods of reducing the initial yawing moment resulting from the failure of one engine were investigated and the equilibrium conditions were explored for two basic modes on one engine, one with zero angle of sideslip and the other with several degrees of sideslip. The added drag resulting from the unsymmetrical attitudes required for flight on one engine was determined for the model airplane. The effects of the application of power upon the stability, controllability, lift, and drag of the model airplane were measured. A dynamic pressure survey of the propeller slipstream was made in the neighborhood of the tail surfaces at three angles of attack. The added parasite drag of the model airplane resulting from the unfavorable conditions of flight on one engine was estimated. From 35 to 50 percent of this added drag was due to the drag of the dead engine propeller and the other 50 to 65 percent was due to the unsymmetrical attitude of the airplane. The mode of flight on one engine in which the angle of sideslip was zero was found to require less power than the mode in which the angle of sideslip was several degrees.

Hartman, Edwin P↗
NASA NTRS1939

Preliminary Model Tests of a Wing-Duct Cooling System for Radial Engines, Special Report

Wind-tunnel tests were conducted on a model wing-nacelle combination to determine the practicability of cooling radial engines by forcing the cooling air into wing-duct entrances located in the propeller slipstream, passing the air through the engine baffles from rear to front, and ejecting the air through an annular slot near the front of the nacelle. The tests, which were of a preliminary nature, were made on a 5-foot-chord wing and a 20-inch-diameter nacelle. A 3-blade, 4-foot-diameter propeller was used. The tests indicated that this method of cooling and cowling radial engines is entirely practicable providing the wing of the prospective airplane is sufficiently thick to accommodate efficient entrance ducts , The drag of the cowlings tested was definitely less than for the conventional N.A.C.A. cowling, and the pressure available at low air speed corresponding to operation on the ground and at low flying speeds was apparently sufficient for cooling most present-day radial engines.

Biermann, David↗
NASA NTRS1985

An experimental investigation of propfan installations on an upswept supercritical wing at transonic Mach numbers

An investigation has been conducted in the Langley 16 Foot Transonic Tunnel to determine propfan installation and slipstream interference effects on an unswept supercritical wing. This data can be used for verification of existing and developing theoretical codes as well as giving an understanding of the flow interactions associated with propeller/nacelle/wing integration. The investigation was conducted over a Mach number range of 0.5 to 0.8 and at angles of attack from 0 deg to 3 deg. The propeller was powered by an air turbine simulator and the exhaust from the air turbine was used to simulate the exhaust from the propfan nacelle. Reynolds number based on wing chord varied from 3 to 4 million. Results indicate that the propfan causes an increase in the wing lift coefficient. It was found that most of the propeller induced swirl is recovered by the wing. The propeller slipstream also causes a large favorable leading edge suction peak on the upwash side and a smaller unfavorable decrease on the downwash side.

Bartlett, G. R.↗
NASA NTRS2016

High-Lift Propeller System Configuration Selection for NASA's SCEPTOR Distributed Electric Propulsion Flight Demonstrator

Although the primary function of propellers is typically to produce thrust, aircraft equipped with distributed electric propulsion (DEP) may utilize propellers whose main purpose is to act as a form of high-lift device. These \high-lift propellers" can be placed upstream of wing such that, when the higher-velocity ow in the propellers' slipstreams interacts with the wing, the lift is increased. This technique is a main design feature of a new NASA advanced design project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR). The goal of the SCEPTOR project is design, build, and y a DEP aircraft to demonstrate that such an aircraft can be much more ecient than conventional designs. This paper provides details into the high-lift propeller system con guration selection for the SCEPTOR ight demonstrator. The methods used in the high-lift propeller system conceptual design and the tradeo s considered in selecting the number of propellers are discussed.

Patterson, Michael D.↗
NASA NTRS1961

Investigation of Longitudinal and Lateral Stability Characteristics of a Six-Propeller Deflected-Slipstream VTOL Model with Boundary-Layer Control Including Effects of Ground Proximity

An investigation of the longitudinal and lateral stability and control and Performance characteristics of a six-propeller deflected- slipstream vertical-take-off-and-landing (VTOL) model in the transition speed range was conducted in the 17-foot test section of the Langley 300-MPH 7- by 10-foot tunnel. A complete analysis of the data was not conducted. A modest amount of blowing boundary-layer control was necessary to achieve transition without wing stall.

Grunwald, Kalman J.↗
NASA NTRS1979

Summary of past experience in natural laminar flow and experimental program for resilient leading edge

The potential of natural laminar flow for significant drag reduction and improved efficiency for aircraft is assessed. Past experience with natural laminar flow as reported in published and unpublished data and personal observations of various researchers is summarized. Aspects discussed include surface contour, waviness, and smoothness requirements; noise and vibration effects on boundary layer transition, boundary layer stability criteria; flight experience with natural laminar flow and suction stabilized boundary layers; and propeller slipstream, rain, frost, ice and insect contamination effects on boundary layer transition. The resilient leading edge appears to be a very promising method to prevent leading edge insect contamination.

Carmichael, B. H.↗
NASA NTRS1980

Propeller slipstream/wing interaction in the transonic regime

An inviscid model for the interaction between a thin wing and a nearly uniform propeller slipstream is presented. The model allows the perturbation velocities due to the interaction to be potential although the undisturbed slipstream velocity is rotational. A finite difference scheme is used to solve the governing equation. Numerical examples indicate that the slipstream has a strong effect on the aerodynamic properties of the wing section within the slipstream and lesser effects elsewhere. The slipstream swirling motion strongly affects the wing load distribution, however, its effect on the wing's total lift and wave drag is small. The axial velocity increment in the slipstream has a small effect on the wing lift, however, it causes a large increase in wave drag.

Rizk, M. H.↗
NASA NTRS1981

Propfan installation aerodynamics of a supercritical swept wing transport configuration

A semispan model with a powered propeller has been tested to provide data on the installation drag penalty of advanced propfan-powered transports designed to cruise at a Mach number of 0.8. These tests, conducted in 14-foot and 11-foot transonic wind tunnels, are a part of a NASA program to develop efficient, high-speed propellers for more fuel-efficient commercial transports for the 1990s and beyond. The model is instrumented for measuring propeller forces, wing/nacelle forces and moments, and pressure distributions over the wing and nacelle. The body in these tests was nonmetric, being connected to the wing by an RTV seal at the wing/body juncture. Tests were run at angles of attack from -3 to +5 deg over the Mach number range 0.6 to 0.85 at a Reynolds number of about 9,000,000. Results of these tests indicate that the nacelle interference drag can be quite large relative to an uninstalled nacelle. However, the losses due to the nacelle were reduced to acceptable levels by changes to the wing leading edge and nacelle intersection. The propeller slipstream causes substantial changes in the wing span load distribution indicating that twist modifications are needed to recover a more favorable span load distribution.

Smith, R. C.↗
NASA NTRS1982

Investigation of a panel code for airframe/propeller integration analyses

The Hess panel code was investigated as a procedure to predict the aerodynamic loading associated with propeller slipstream interference on the airframe. The slipstream was modeled as a variable onset flow to the lifting and nonlifting bodies treated by the code. Four sets of experimental data were used for comparisons with the code. The results indicate that the Hess code, in its present form, will give valid solutions for nonuniform onset flows which vary in direction only. The code presently gives incorrect solutions for flows with variations in velocity. Modifications to the code to correct this are discussed.

Miley, S. J.↗
NASA NTRS1983

Transonic flow simulation of prop-fan configurations

This paper presents the results of a study that used a three-dimensional transonic analysis method to analyze flow around a wing-mounted prop-fan configuration. The transonic analysis method employs a cell-oriented finite volume approach to solve the full potential equation in conservative form over a numerically generated surface-fitted grid. The propeller slipstream effects are simulated using a linearized transpiration boundary condition. The results of analyses of flow over clean wing/body, wing/body/nacelle, and wing/body nacelle with slipstream are compared to test data.

Samant, S. S.↗
NASA NTRS1982

NASA aerial applications wake interaction research

A computer code has been developed for predicting trajectories of particles released in the wakes of airplanes or helicopters. The code accounts for effects of turbulence, crosswind, propeller slipstream, terrain variations, and plant canopy density on particle trajectories. Comparisons are given between experiments and theory. Applications of the code for spray pattern improvement are illustrated.

Morris, D. J.↗
NASA NTRS1983

PAN AIR modeling studies

PAN AIR is a computer program that predicts subsonic or supersonic linear potential flow about arbitrary configurations. The code's versatility and generality afford numerous possibilities for modeling flow problems. Although this generality provides great flexibility, it also means that studies are required to establish the dos and don'ts of modeling. The purpose of this paper is to describe and evaluate a variety of methods for modeling flows with PAN AIR. The areas discussed are effects of panel density, internal flow modeling, forebody modeling in subsonic flow, propeller slipstream modeling, effect of wake length, wing-tail-wake interaction, effect of trailing-edge paneling on the Kutta condition, well- and ill-posed boundary-value problems, and induced-drag calculations. These nine topics address problems that are of practical interest to the users of PAN AIR.

Towne, M. C.↗
NASA NTRS1983

Flight investigation of natural laminar flow on the Bellanca Skyrocket II

Two major concerns have inhibited the use of natural laminar flow (NLF) for viscous drag reduction on production aircraft. These are the concerns of achieveability of NLF on practical airframe surfaces, and maintainability in operating environments. Previous research in this area left a mixture of positive and negative conclusions regarding these concerns. While early (pre-1950) airframe construction methods could not achieve NLF criteria for waviness, several modern construction methods (composites for example) can achieve the required smoothness. This paper presents flight experiment data on the achieveability and maintainability of NLF on a high-performance, single-propeller, composite airplane, the Bellanca Skyrocket II. The significant contribution of laminar flow to the performance of this airplane was measured. Observations of laminar flow in the propeller slipstream are discussed, as are the effects of insect contamination on the wing. These observations have resulted in a new appreciation of the operational feasibility for achieving and maintaining NLF on modern airframe surfaces.

Holmes, B. J.↗
NASA NTRS1983

NASA wake interactions research and applications

This report describes the development, validation, and application of a computer program for predicting trajectories and ground deposit patterns for particle released in the wakes of airplanes or helicopters. The computer program accounts for the effects of atmospheric turbulence, crosswind, propeller slipstream, terrain variations, evaporation, and plant canopy density on the particle trajectories. In order to validate the prediction method, some comparisons are shown between experimental data and theoretical predictions. Possible applications of the code for spray pattern improvement and for mission operations analysis are illustrated. In addition, the effect of winglets on pattern uniformity, drift, and airplane aerodynamics are presented.

Morris, D. J.↗
NASA NTRS1983

A modified lifting line theory for wing-propeller interference

An inviscid incompressible model for the interaction of a wing with a single propeller slipstream is presented. The model allows the perturbation quantities to be potential even though the undisturbed flow is rotational. The governing equations for the spanwise lift distribution are derived and a simple method of solving these is indicated. Spanwise lift and induced drag distribution for two cases are computed.

Prabhu, R. K.↗
NASA NTRS1981

A numerical simulation of the dispersal of aerial sprays

A computer program was developed to predict the trajectory, ground deposition, and drift of liquid sprays injected into the wake of an agricultural aircraft in ground effect. The program uses a horseshoe vortex wake model and includes the effects of liquid droplet evaporation, crosswind, the propeller slipstream, ground effect, and tunnel walls on small scale models. This user's guide includes several case examples demonstrating user options. A complete listing of the FORTRAN program is provided.

Bragg, M. B.↗
NASA NTRS1984

Elements of computational engine-airframe integration

Computerized flow simulation methods are being developed to refine the traditional engine-airframe integration process. These analyses reduce design risk, minimize wind tunnel and flight test requirements, and provide detailed design information not available by any other means. This paper describes computational tools which have matured sufficiently to permit project applications. Several applications are combined with research studies to illustrate the prediction of high-speed nonlinear phenomena associated with engine inlet flow rate, nacelle shape and position, afterbody shape and integration, propeller slipstream interactions, airframe-induced inlet flow, and pylon integration. Both fighter and transport configurations are used to highlight current capabilities and future requirements.

Boppe, C. W.↗
NASA NTRS1985

Simulation study of an automatic trim system for reducing the control forces on a light twin after an engine failure

An automatic trim system for reducing the control forces after an engine failure on a light twin has been investigated on the Langley General Aviation Simulator. The system schedules open-loop trim tab deflections as a function of differential propeller slipstream dynamic pressure and freestream dynamic pressure. The system is described and the airplane-system static and dynamic characteristics are documented. Three NASA research pilots evaluated the effectiveness of the system for takeoff and landing maneuvers. A variety of off-nominal system characteristics were studied. The system was judged to be generally beneficial, providing a 2 to 3 point improvement in pilot rating for the tasks used in the evaluations.

Stewart, E. C.↗