Engineering topics

Jones, R. T.

Publications and source records attributed to Jones, R. T..

At least 73 records · Page 4

NASA NTRS1976

Reduction of wave drag by antisymmetric arrangement of wings and bodies

In theory, antisymmetric arrangements of wings and bodies can have smaller wave drag than corresponding mirror-symmetric arrangements. Thus, a long narrow oblique wing which presents the same aspect for two opposite directions of flight is potentially more efficient than corresponding (i.e., structurally equivalent) swept wing. The single continuous wing panel also adapts itself more readily to varying angles of obliquity, and hence, to varying flight speeds. Previous work on the aerodynamics and flight stability of oblique wing combinations is reviewed and a possible mode of application to transport aircraft operating at moderate supersonic speeds is suggested.

Jones, R. T.↗

NASA NTRS1976

Aircraft design for flight below the sonic boom speed limit

The avoidance of sonic booms places a constraint on aircraft design and can lead to unusual new configurations. From a comparison among several candidate designs, it is shown that an oblique winged aircraft offers many advantages when structure, stability, flight efficiency, and airport noise are considered jointly.

Jones, R. T.↗

NASA NTRS1976

Aeroelastic characteristics of an oblique wing

In theory, the most efficient wing shape for transonic and low supersonic speeds is simply a long narrow straight subsonic wing turned at an oblique angle to the flight direction. This theory has been verified by tests at Mach numbers from .6 to 1.4 in supersonic wind tunnel and by comparative studies of transonic transport designs.

Jones, R. T.↗

NASA NTRS1976

Coma of modified Gregorian and Cassegrainian mirror systems

The equivalence of the classical Newtonian, Cassegrainian, and Gregorian mirror systems with respect to the first two Seidel aberrations is rederived by means of a simple congruence. The effects of arbitrary small modifications of the two mirror systems are then studied and general formulas are derived for the effects of such modifications on the spherical aberration and coma. Spherical aberration is corrected to the third order if the amount of glass removed from one surface is replaced at the corresponding zone of the other surface. Modifications in which one surface is made spherical while the other is adjusted to eliminate spherical aberration result in large increases of coma for systems having the usual amplifying ratios.

Jones, R. T.↗

NASA NTRS1976

A wide-field telescope with spherical optics

Utilizing a doublet lens to correct the aberrations of a spherical mirror, a small f/8 telescope for visual use was designed and constructed. The lens has considerable negative power, so that it serves as a Barlow lens as well as a corrector.

Jones, R. T.↗

NASA NTRS1976

Space science: Some selected problems and accomplishments

The development of scientific satellites is briefly discussed with emphasis on exhaust velocity enhancement by various propulsion system configurations. Also reported is the experimental production of artificial auroras at points separated by thousands of miles over the earth by creating relativistic electrons.

Jones, R. T.↗

NASA NTRS1976

Wide angle lenses with aspheric correcting surfaces

Refracting elements having aspheric correcting surfaces near the center of curvature are analyzed. As in the case of the Schmidt reflector, such systems can have a wide aperture and a wide field of view; in addition, they are free from obstructing surfaces. Being uncorrected for dispersion, however, the refracting systems are restricted to nearly monochromatic radiation. Typical forms of the correcting surfaces have been determined, both by third order theory and by numerical integration of exact equations.

Jones, R. T.↗

NASA NTRS1976

Times for interplanetary trips

The times required to travel to the various planets at an acceleration of one g are calculated. Surrounding gravitational fields are neglected except for a relatively short distance near take-off or landing. The orbit consists of an essentially straight line with the thrust directed toward the destination up to the halfway point, but in the opposite direction for the remainder so that the velocity is zero on arrival. A table lists the approximate times required, and also the maximum velocities acquired in light units v/c for the various planets.

Jones, R. T.↗

NASA NTRS1976

Extending the Lorentz transformation by characteristic coordinates

The problem considered is that of rectilinear motion with variable velocity. The paper gives, by an elementary construction, a system of coordinates which is conformal in a restricted region near the axis of the motion. In such coordinates the velocity of light remains invariant even for observers moving with variable velocity. By a particular choice of the scale relation the restricted conformal transformations can be made to reduce to the Lorentz transformation everywhere in the case of constant velocity and locally in the case of variable velocity.

Jones, R. T.↗

NASA NTRS1976

Analysis of accelerated motion in the theory of relativity

Conventional treatments of accelerated motion in the theory of relativity have led to certain difficulties of interpretation. Certain reversals in the apparent gravitational field of an accelerated body may be avoided by simpler analysis based on the use of restricted conformal transformations. In the conformal theory the velocity of light remains constant even for experimenters in accelerated motion. The problem considered is that of rectilinear motion with a variable velocity. The motion takes place along the x or x' axis of two coordinate systems.

Jones, R. T.↗

NASA NTRS1976

Conformal coordinates associated with uniformly accelerated motion

Specific problems in the theory of relativity are often simplified by an appropriate choice of the coordinate system. Restricted conformal coordinates provide an especially simple analysis of motion with uniform acceleration, known as hyperbolic motion. Conformal coordinates x', t' may be obtained from Cartesian coordinates x, t by the transformation x'+ct'=F(x+ct) and x'-ct'=G(x-ct), where c is the velocity of light. A variable motion of the x' system is determined by the choice of the functions F and G.

Jones, R. T.↗

NASA NTRS1976

Conformal coordinates associated with space-like motions

Conformal transformations in two dimensions provide a simple extension of the Lorentz transformation. The velocity of light appears in such transformations as a singular velocity rather than as an upper limit for the velocity. A well ordered branch of the theory exists for velocities in excess of the velocity of light. If the velocity of a point exceeds the singular velocity in an inertial system, then the conformal representation of the motion is no longer uniform, but contains a folded region. However, the branching of the transformation may be determined so that the elapsed time along the path of such a motion remains positive. Kinematic relations on the other side of the singular velocity seem to complement the usual results of relativity theory in an interesting way. Thus it is known that motion at the speed of light occurs along a null geodesic, and hence corresponds in a certain sense to motion at infinite velocity. The complementary relation is that a motion of infinite velocity corresponds in the same sense to motion at the speed of light.

Jones, R. T.↗

NASA NTRS1976

Motions of a liquid in a pulsating bulb with application to problems of blood flow

Potential flows may be utilized to represent motions produced in pulsating bulbs. While the initial bulb shape may be arbitrary, sequential shapes are related by affine transformations. Two components appear in the distribution of pressure, one dependent on the instantaneous velocity and the other on the acceleration. For flows with stationary streamlines the inertial impedance is that of a simple mass, and is proportional to the first moment of the actual mass of fluid contained within the bulb. Examples treated are: (1) Expanding and collapsing circular cylinders, and (2) elliptical cylinders in which the perimeter is held constant. The thickness of the pulsatile laminar boundary layer is found to be approximately on millimeter for conditions in the vicinity of the heart. Conditions for separation and turbulence differ from those in steady flow.

Jones, R. T.↗

NASA NTRS1976

Elementary theory of synchronous arterio-arterial blood pumps

In the technique of arterio-arterial pumping, a volume of fluid is withdrawn from the aorta during systole and reinjected during diastole, thereby reducing the systolic pressure of the heart and adding energy to the systemic circulation. It is found that an upper bound for the effectiveness of such devices is given by a formula that considers stroke output of the unaided heart and the increment caused by the pump with a stroke. The division of effort of the pump between the reduction of pressure and the increase of flow depends on the physiological mechanical impedance of the heart. The total effect is, however, independent of the impedance.

Jones, R. T.↗

NASA NTRS1976

Blood flow

A heuristic treatment of blood flow in the heart and the aorta together with some of the main branches considers the effects of fluid viscosity and vessel elasticity as well as pressure distribution in the typical pulsating flow.

Jones, R. T.↗

NASA NTRS1976

Fluid dynamics of heart assist device

Certain hemodynamic phenomena that arise in connection with the use of artificial blood pumping devices are reviewed. Among these are: (1) Flows produced by collapsing bulbs; (2) the impedance presented by the aorta; (3) limiting velocities and instability of flow in elastic vessels; (4) effectiveness of valveless arterio-arterial pumps, and (5) wave reflection phenomena and instabilities associated with the intra-aortic balloon pump.

Jones, R. T.↗

NASA NTRS1976

A simple violin oscillator

For acoustic tests the violin is driven laterally at the bridge by a small speaker of the type commonly found in pocket transistor radios. An audio oscillator excites the tone which is picked up by a sound level meter. Gross patterns of vibration modes are obtained by the Chladni method.

Jones, R. T.↗

NASA NTRS1975

Some considerations in the design of transport aircraft /The W. Rupert Turnbull Lecture for 1975/

The slow landing speeds (30 mph, 65 mph) and light wing loading required for safety in the early days of aviation are shown to be irrelevant to safe landings of propeller-driven aircraft, while increases in wing loading and landing speed have been accompanied by improved safety records. This is attributed to length of runway and time available for approach maneuvers, plus immunity to wind gusts and turbulence conferred by higher wing loadings. Aerodynamical and mechanical aspects of safe landing are discussed, with no mention of instruments. Fuel savings achievable through high aspect ratio, variable sweep angle, and supercritical airfoils are also considered.

Jones, R. T.↗