Report presenting numerical results of flutter calculations for a two-blade helicopter using a see-saw-type rotor. The stability condition for oscillatory motion is expressed in terms of a small number of composite parameters that are evaluated from moments of inertia, angle settings, and aerodynamic parameters of a blade. The analysis indicated that a see-saw rotor with a coning angle is more unstable than an airplane wing with the same parameters.

Memorandum presenting a fineness-ratio-2.71 right circular cylinder and a fineness-ratio-4.0 circular cylinder with a rounded nose and a flared afterbody tested in free flight over a range of Mach and Reynolds numbers. Time histories, cross plots of force coefficients, rolling velocity, and longitudinal-force coefficient are presented for both cylinders.

Report presenting testing of a fineness-ratio-2.71 right circular cylinder and a fineness-ratio-4.0 circular cylinder with a rounded nose and flared afterbody over a range of Mach and Reynolds numbers. Time histories, cross plots of force coefficients, rolling velocity, and longitudinal-force coefficient are provided for the two cylinders.

Report presenting the results of an investigation to determine the static longitudinal and lateral stability and control characteristics of a model of the Republic MX-1554 airplane at a specified Mach and Reynolds number. No analysis was provided in the paper in order to expedite publication.

Report presenting an experimental investigation of several airplane configurations at Mach 3.0 in a continuous flow tunnel. The configurations had circular fuselage cross sections and a sweptback wing and either two nacelles or two side inlets.

Report presenting an investigation of the physical properties of slurries and the use of a metal-soap additive to prepare stable slurries of commercial magnesium, aluminum, and boron powders in a MIL-F-5624 grade JP-3 base fuel. Results regarding the slurry density, apparent viscosity, apparent surface tension, stability, and fuel-flow characteristics are provided.

Report presenting the performance characteristics of a turbine with nontwisted rotor blades suitable for air cooling. Results regarding overall performance and flow surveys at the stator and rotor exits are provided.

"Profile-drag coefficients published from tests in the N.A.C.A. variable-density tunnel (Technical Reports Nos. 460, 537, 586, and 610, references 1 to 4) have tended to appear high as compared with results from the N.A.C.A. full-scale tunnel (Technical Report No. 530, reference 5) and from foreign sources (references 6 to 8). Such discrepancies were considered in Technical Report No. 586, and corrections for turbulence and tip effects were derived that tended to reduce the profile-drag coefficients, particularly for the thicker airfoils. The corrected profile-drag coefficients, designated by the lower-case symbol cdo as contrasted with the older CDO, have been employed in the airfoil reports published since Technical Report No. 460, but even these corrected results continued to appear high, particularly for the thicker sections" (p. 1).

From Introduction: "Results from the tests in the Langley 4- by 4-foot supersonic pressure tunnel at Mach numbers of 1.61 and 2.01 are presented in reference 1. Reported herein are results obtained from the tests in the Langley 8-foot transonic tunnel of the model with no control deflections at Mach numbers 0.6 to 1.12 for angles of attack up to 34^o

Report presenting an investigation of a scale model of a jet airplane equipped with hydro-skis to study the transition between ramp and water during take-off and landing operations. Hydro-skis were installed so that they utilized the existing landing-gear shock absorbers. Results regarding the twin-ski configuration and tri-ski configuration are provided.

"This report gives the full-scale aerodynamic characteristics of five different aluminum alloy propellers having four different blade forms. They were tested on an open cockpit fuselage with a radial air-cooled engine having conventional cowling. The results show that (1) the differences in propulsive efficiency due to the differences in blade form were small; (2) the form with the thinnest airfoil sections had the highest efficiency; (3) it is advantageous as regards propulsive efficiency for a propeller operating in front of a body, such as a radial engine, to have its pitch reduced toward the hub" (p. 123).

From Introduction: "This report represents an extension of the material presented in reference 4 to the case of the counterrotating turbine where the inter-stage stator is omitted and the second-stage rotor blade velocity is in the direction opposite to that of the first-stage rotor."

An analysis is presented of rim cooling of gas-turbine blades; that is, reducing the temperature at the base of the blade (wheel rim), which cools the blade by conduction alone. Formulas for temperature and stress distributions along the blade are derived and, by the use of experimental stress-rupture data for a typical blade alloy, a relation is established between blade life (time for rupture), operating speed, and amount of rim cooling for several gas temperatures. The effect of blade parameter combining the effects of blade dimensions, blade thermal conductivity, and heat-transfer coefficient is determined. The effect of radiation on the results is approximated. The gas temperatures ranged from 1300F to 1900F and the rim temperature, from 0F to 1000F below the gas temperature. This report is concerned only with blades of uniform cross section, but the conclusions drawn are generally applicable to most modern turbine blades. For a typical rim-cooled blade, gas temperature increases are limited to about 200F for 500F of cooling of the blade base below gas temperature, and additional cooling brings progressively smaller increases. In order to obtain large increases in thermal conductivity or very large decreases in heat-transfer coefficient or blade length or necessary. The increases …

Report presenting a method for calculating flutter characteristics of finite-span swept or unswept wings at subsonic and supersonic speeds. Flutter characteristics were calculated using this method for 12 wings of varying sweep angle, aspect ratio, taper ratio, and center-of-gravity position at a range of Mach numbers.

This document contains reproductions of technical papers presented by staff members of the NACA Laboratories at the NACA Conference on High-Speed Aerodynamics held at the Ames Aeronautical Laboratory of the NACA, March 18, 19, and 20, 1958. The primary purpose of this conference was to convey to the military services and their contractors the results of recent research results and to provide those attending an opportunity to discuss the results. The papers in this document were prepared for presentation at the conference and are considered as complementary to, rather than as substitutes for, the Committee's more complete and formal reports.

A reproduction of the technical papers presented by staff members of the NACA Laboratories at the NACA Conference on High-Speed Aerodynamics at the Ames Aeronautical Laboratory during March 18-20, 1958. The primary purpose of the conference was to convey to military services and contractors the results of recent research and to provide an opportunity to discuss the results.