Calculations Showing the Influence of Aerodynamic Damping on Binary Wing Flutter
The influence of damping is examined by comparing the flutter critical speeds and frequencies obtained using the complete equations of motion and those obtained when all the damping terms are omitted. The calculations are made for binary flexure-torsion flutter of a wing in incompressible flow and the comparisons extend over ranges of values of the principal parameters. When the ratio of air density to wing density is high, the damping terms are found to raise the flutter speed by a large amount. But when the ratio of air density to wing density is low, a condition often occurring in practice, it appears that, over a wide range of parameter variation, the flutter speed obtained in the absence of damping is reasonably close to that obtained from the complete equations. Further experience is obviously needed before any general conclusions can be re~¢hed, but the present results offer some hope of reducing either the extent of, or the accuracy needed in, the aerodynamic information used for wing flutter calculations. It is pointed out that with constant aerodynamic coefficients the flutter speed for an undamped system is independent of the wing density.
Some general considerations concerning the destabilizing effect in nonconservative systems
ZusammenfassungEs wird ein lineares System mitN Freiheitsgraden untersucht, beansprucht durch eine Gruppe nichtkonservativer Kräfte, welche linear von den verallgemeinerten Koordinaten abhängen. Mehrere Sätze bezüglich die labilisierende Wirkung von kleinen Kräften, die von den verallgemeinerten Geschwindigkeiten abhängen, werden aufgestellt. Diese Kräfte können von der Dämpfung oder von gyroskopischen Einflüssen herrühren.
To Devolve or Not To Devolve? Welfare Reform in the States
This article analyzes variation in the degree to which states have responded to the devolution of welfare at the federal level by devolving authority over welfare policy to local government. I find that to the extent that states have devolved authority to lower levels of government, they tend to be states that already had a high degree of involvement of local government in welfare provision. In states without this record of local government involvement, the devolution that has occurred has not generated greater involvement of local government, but rather responsibility has been devolved to regional entities with ties to workforce development and with a substantial degree of business involvement. As states gain increasing authority over a redistributive policy, they may begin to treat it as a subset of a larger developmental policy—workforce development.