Short Bodies Research Articles

First-Order Treatment of Higher-Order Boundary-Layer Effects

The effects of transverse curvature, shock-generated external vorticity, boundary-layer displacement, and wall slip and temperature jump are considered as first-order boundary-layer effects. The classical boundary-layer equations were modified to include the higher-order effects, and flows over a 9-deg half-angle blunt cone were considered at M∞ = 9 and 18. Comparisons are made with second-order theory and experimental data. Primary interest is given to predicting the higher-order effects on zero-lift drag and comparsion with experimental data. Range of applicability of higher-order boundary-layer theory is indicated based upon the ability to predict zero-lift drag. Vorticity was the dominant higher-order effect, and the theory is most applicable to relatively short slender bodies. At very low Reynolds numbers, strong coupling of the higher-order effects was found to exist.

Magnus characteristics of finned and nonfinned projectiles

This is a summary of the Magnus force and moment measurements obtained on finned and nonfinned projectiles during the past several years. Most of the measurements have been obtained in the Ballistic Research Laboratories' (BRL) supersonic wind tunnels, with a few measurements taken in the BRL transonic range and the Naval Ordnance Laboratory's wind tunnels. The results have provided considerable insight into the generation of the Magnus force and moments on both finned and nonfinned projectiles. For nonfinned bodies at small angles of attack, having a laminar boundary layer, the Magnus force, at least on short bodies, obeys Martin's theory. At high angles of attack the Magnus force can be estimated from the lift force on a spinning cylinder flying perpendicular to the flow. The Magnus force on a spinning finned projectile is composed of two forces: a body force and a fin force. The forces normally act in opposite directions, thereby tending to cancel one another. However, the forces do not act at the same location; therefore a Magnus moment is created which is nearly independent of the center of gravity position. There are also two other known sources of Magnus moments on finned bodies which are created under certain conditions. These conditions are defined in this paper and the magnitude of the moments are estimated.

Axial Elongation in the Mouse and its Retardation in Homozygous Looptail Mice

ABSTRACT Mice homozygous for the mutation Looptail have shorter bodies than normal homozygous or heterozygous littermates. Shortening is relatively greater in the posterior portion of the embryo. The regression or the shortening of the primitive streak is retarded but the separation of notochord from gut occurs prematurely in the abnormal embryos. Umbilical cords are shorter in Lp/Lp mice than in normal embryos or in heterozygotes. The possible significance of these facts in relation to the open neural folds in the homozygous Lp/Lp mice is discussed.

The development of rana temporaria under the influence of cane sugar solution

The main object of the investigations, the results of which are embodied in this paper, was to repeat certain experiments performed by Tornier (1908) and to confirm or confute his conclusions. Tornier experimented with the eggs of Amphibia— Rana, Bufo and in particular the Axolotl ( Amblystoma ), keeping them for 48 hours in an 8 per cent. solution of cane sugar, then transferring them for 24 hours to a 2 per cent. Solution, and after that to well aerated water in which they completed their development. As a result of this treatment, in further development all sorts of abnormalities, turned up, such as short bodies, swollen abdomens, enlarged mouth cavities, etc. Since similar abnormalities were produced by the use of solutions of glycerine and common salt, Tornier concluded that the energy of the germinal part of the egg had been affected by the reagents used, and that what he termed “plasma-weakness” had been produced, so that the yolky part of the egg, being no longer controlled, swelled up and crushed the more protoplasmic part. He thought that the weakness was immediately due to the cutting off of oxygen by the reagent. He considered that the results which he had obtained with Amphibian eggs explained the production of the “fancy” races of goldfish, because the Chinese breeders, with whom these races originated, were accustomed to rear the spawn of their fish in foul water.

On the effect of the form of the transverse section on the frictional resistance to the motion of an elongated body parallel to its length through a fluid

1. The great increase in tire lengths of the parallel mid-bodies of recently constructed submarines and airships has raised into prominence the question of the frictional resistance of such elongated bodies moving parallel to their length through fluids, like air and water, whose viscosities cannot be neglected. This resistance increases as the length increases, and benefits comparable with the head and tail resistances, which for short bodies constitute nearly the whole resistance. In general, the problem of greatest practical importance is the determination of the frictional resistance when the motion is rapid enough to produce eddy currents in the fluid, but the difficulties in the way of a general theory of eddy current motion have presented a solution being reached. The simpler problem of the resistance offered by the walls of a circular pipe to the turbulent flow of viscous fluid through the pipe formed the subject of extensive series of experiments by Saph and Schoder, of Cornell University, and by Stanton and Pannell at the National Physical Laboratory.

A NEW SILK-SPINNING CHALCID

During the summer of 1879, while working with Professor Comstock upon the natural enemies of the cotton worm, I came across the following passage in his fleld notes of the previous year :—“August 27.–I found yesterday a cotton worm about five-eighths of an inch in length, which, though yet alive, was being destroyed by three green larvæ which were upon it. I found the specimens abont 10 a. m. Last evening I observed that the cotton worm was nearly eaten. The parasites had very short bodies, which, when they moved, were pointed at one end. I had intended to describe the specimens, but I find that they have spun cocoons about their bodies.