An investigation of detached shock waves

This investigation demonstrates an application of a flexible wall nozzle for testing in a supersonic wind tunnel. It is conservative to say that the versatility of this nozzle is such that it warrants the expenditure of time to carefully engineer a nozzle and incorporate it in the wind tunnel as a permanent part of the system. The gradients in the test section were kept within one percent of the calibrated Mach number, however, the gradients occurring over the bodies tested were only ± 0.2 percent in Mach number.

The conditions existing on a finite cone with a vertex angle of 75° were investigated by considering the pressure distribution on the cone and the shape of the shock wave. The pressure distribution on the surface of the 75° cone when based on upstream conditions does not show any discontinuities at the theoretical attachment Mach number.

Both the angle of the shock wave and the pressure distribution of the 75° cone are in very close agreement with the theoretical values given in the Kopal report, (Ref. 3).

The location of the intersection of the sonic line with the surface of the cone and with the shock wave are given for the cone. The blocking characteristics of the GALCIT supersonic wind tunnel were investigated with a series of 60° cones.

Geology of the Pacoima Hills

The Pacoima Hills lie between Foothill Boulevard and the San Fernando Road, three miles southeast of San Fernando, California. In this area are exposed Jurassic(?) granodiorite intruded in older gneiss, and a mid Miocene Topango (?) sedimentary section lying in both fault and sedimentary contact with the intrusive complex. Two distinct lava flows and a small laccolith of andesite occur within the Topango (?) formation. The principal structural feature is an anticline plunging steeply northward. An upward acting force is postulated to have produced this anticline; upon cessation of the force, normal faulting occurred with consequent down-dropping of north-south blocks.

Geomorphology of a Portion of the Easternmost Ventura Basin

The Humphreys Quadrangle is a portion of the easternmost Ventura Basin underlain by a thick series of Tertiary sedimentary rocks. On these rocks a great variety of geomorphic forms have been molded by the processes of running water typical of a semi-arid climate and by several types of mass movement. Among the different categories of mass movement present, a new type, the siltflow, was observed.

The geomorphic forms of special interest present in the quadrangle are rock cones, open canyonheads, asymmetric canyons, and stream terraces and straths. The author urges the adoption of the definition of strath as that part of an old dissected valley floor, including the floors of tributary valleys, which was not part of the floodplain of the main valley stream.

An old erosion surface, the Puckett Mesa Surface, is present in the Humphreys Quadrangle which is correlative with certain of the older stream terraces. By correlating the variation of gradient and of fill of the stream terraces with post –Wisconsin climatic fluctuations the age of the Puckett Mesa Surface is set at approximately 6000 B.C. This correlation sets the probable age of the older Rancho La Brea deposits at 6000 to 8000 B. C. and the probable age of the Carpenteria brea deposits at 1000 to 1 B. C.