Dihedral
WING DIHEDRAL is an important consideration in the design of all aircraft. For many model aircraft dihedral is a crucial element of the design strongly affecting performance and handling. This four-part article will examine dihedral in detail. The Dihedral Effect will explain the dihedral mechanism and present a method of dihedral quantification. The Steady State Roll will examine the effect of dihedral on the rolling maneuver and will present a means of calculating roll rate.
Dihedral
THREE BASIC MANEUVERS involve the roll axis of the airplane: straight and level flight, steady-state circling, and steady-state rolling. This article will discuss the steady-state roll. A means to predict roll rate will be presented in detail. The effect of different dihedral arrangements on rolling properties will also be described. Part three of the series will discuss steady-state circling and the relationship of dihedral to spiral stability.
Dihedral
THE ARTICLE will look at what happens to a wing during steady-state circling. Circling is the most common maneuver for most Gliders. Free Flight models circle constantly after the launch, and RC Sailplanes typically spend much of their time circling while working thermals. Steady-state circling requires a remarkable amount of yaw. A method to estimate this yaw is presented. Based on this, a method to evaluate spiral stability is described. Spiral stability is one of the most important aspects of flying these models.
Dihedral
BECAUSE wings with dihedral have more surface area than flat wings producing the same net lift, they are less efficient. The first part of this article examines this issue and quantifies the efficiency loss. The second part of the article wraps up the four-part series with a discussion of how to choose dihedral type and quantity.
Spiral Stability and the Bowl Effect
Introduction. This two-part article addresses spiral stability. The first part describes what is required of an aircraft design to achieve full spiral stability. The conclusion next month describes how the bole-shaped flight path of a circling airplane affects flight behavior. This work is an outgrowth of my four-part series "Dihedral," published in the August through November 1988 issues of Model Aviation. Spiral stability refers to a plane's natural ability to hold a trimmed course. This characteristic is crucial to the performance of Free Flight models and to the handling and performance of radio-controlled Sailplanes.
