Static longitudinal stability and longitudinal control of autogiro rotors

The present report discusses three different systems of elevator control and their effects on the stability and maneuverability of autogiros: (a) ailerons and elevators (standard); (b) blade control (la Cierval); (c) gravity control (new)

Aerodynamic computation of gliders

In the following discussion, a knowledge of the theoretical principles of airplane construction is assumed, as presented in detail by Vogt and Lippisch. A few quantities will however be otherwise designated, in accordance with the Gottingen symbols

High-speed Aircraft

This report details the designs of high-speed aircraft from various countries from 1931 on, with special emphasis on the United States and Germany

Gaussian model of explosive percolation in three and higher dimensions

The Gaussian model of discontinuous percolation, recently introduced by Ara\'ujo and Herrmann [Phys. Rev. Lett., 105, 035701 (2010)], is numerically investigated in three dimensions, disclosing a discontinuous transition. For the simple-cubic lattice, in the thermodynamic limit, we report a finite jump of the order parameter, $J=0.415 \pm 0.005$. The largest cluster at the threshold is compact, but its external perimeter is fractal with fractal dimension $d_A = 2.5 \pm 0.2$. The study is extended to hypercubic lattices up to six dimensions and to the mean-field limit (infinite dimension). We find that, in all considered dimensions, the percolation transition is discontinuous. The value of the jump in the order parameter, the maximum of the second moment, and the percolation threshold are analyzed, revealing interesting features of the transition and corroborating its discontinuous nature in all considered dimensions. We also show that the fractal dimension of the external perimeter, for any dimension, is consistent with the one from bridge percolation and establish a lower bound for the percolation threshold of discontinuous models with finite number of clusters at the threshold

Recent advances and open challenges in percolation

Percolation is the paradigm for random connectivity and has been one of the most applied statistical models. With simple geometrical rules a transition is obtained which is related to magnetic models. This transition is, in all dimensions, one of the most robust continuous transitions known. We present a very brief overview of more than 60 years of work in this area and discuss several open questions for a variety of models, including classical, explosive, invasion, bootstrap, and correlated percolation

Welding in airplane construction

The present article attempts to explain the principles for the production of a perfect weld and to throw light on the unexplained problems. Moreover, it is intended to elucidate the possibilities of testing the strength and reliability of welded parts