TeV Cherenkov Events as Bose-Einstein Gamma Condensations

The recent detection of gamma radiation from Mkn 501 at energies as high as 25 TeV suggests stringent upper bounds on the diffuse, far infrared, extragalactic radiation density. The production of electron-positron pairs through photon-photon collisions would prevent gamma photons of substantially higher energies from reaching us across distances of order 100 Mpc. However, coherently arriving TeV or sub-TeV gammas - Bose-Einstein condensations of photons at these energies - could mimic the Cherenkov shower signatures of extremely energetic gammas. To better understand such events, we describe their observational traits and discuss how they might be generated.Comment: 12 pages, 2 figures, accepted for publication in Ap.J.(Lett.

Ultra High Energy Cosmic Rays from Sequestered X Bursts

Assuming that there is no GZK (Greisen-Zatsepin-Kuzmin) cut-off and that super-GZK cosmic rays correlate with AGN (Active Galactic Nuclei) at cosmological distances, it is speculated that a relic superheavy particle (X) has its lifetime enhanced by sequestration in an extra dimension. This sequestration is assumed to be partially liberated by proximity of merging supermassive black holes in an AGN, temporarily but drastically reducing the lifetime, thus stimulating an X burst. Based on sequestration of the decay products of X, a speculative explanation of the observed $\gamma/N$ ratio is proposed.Comment: 12 pages LaTe

Wind-Tunnel Investigation of Rectangular Air-Duct Entrances in the Leading Edge of an NACA 23018 Wing, Special Report

A preliminary investigation of a number of duct entrances of rectangular shape installed in the leading edge of a wing was conducted in the NACA 20-foot tunnel to determine the external drag, the available pressure, the critical Mach numbers, and the effect on the maximum lift. The results showed that the most satisfactory entrances, which had practically no effect on the wing characteristics, had their lips approximately in the vertical plane of the leading edge of the wing. This requirement necessitated extending the lips outside the wing contour for all except the small entrances. Full dynamic pressure was found to be available over a fairly wide range of angle of attack. The critical Mach number for a small entrance was calculated to be as high as that for the plain wing but was slightly lower for the larger entrances tested

The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears II : Nonretractable and Partly Retractable Landing Gears

This is the second report giving the results obtained in the NACA 20-foot wind tunnel on the drag due to landing gears. The present report gives the results of tests of nonretractable and partly retractable landing gears intended for heavier low-wing monoplanes of the transport and bomber type