Preliminary system design study for a digital fly-by-wire flight control system for an F-8C aircraft

The design of a fly-by-wire control system having a mission failure probability of less than one millionth failures per flight hour is examined. Emphasis was placed on developing actuator configurations that would improve the system performance, and consideration of the practical aspects of sensor/computer and computer/actuator interface implementation. Five basic configurations were defined as appropriate candidates for the F-8C research aircraft. Options on the basic configurations were included to cover variations in flight sensors, redundancy levels, data transmission techniques, processor input/output methods, and servo actuator arrangements. The study results can be applied to fly by wire systems for transport aircraft in general and the space shuttle

Determination of the Stability and Control Characteristics of a Tailless All-Wing Airplane Model with Sweepback in the Langley Free-Flight Tunnel

Force and flight tests were performance on an all-wing model with windmilling propellers. Tests were conducted with deflected and retracted flaps, with and without auxiliary vertical tail surfaces, and with different centers of gravity and trim coefficients. Results indicate serious reduction of stick-fixed longitudinal stability because of wing-tip stalling at high lift coefficient. Directional stability without vertical tail is undesirably low. Low effective dihedral should be maintained. Elevator and rudder control system is satisfactory

The Effect of Mass Distribution on the Lateral Stability and Control Characteristics of an Airplane as Determined by Tests of a Model in the Free-flight Tunnel

The effects of mass distribution on lateral stability and control characteristics of an airplane have been determined by flight tests of a model in the NACA free-flight tunnel. In the investigation, the rolling and yawing moments of inertia were increased from normal values to values up to five times normal. For each moment-of-inertia condition, combinations of dihedral and vertical-tail area representing a variety of airplane configurations were tested. The results of the flight tests of the model were correlated with calculated stability and control characteristics and, in general, good agreement was obtained

The Creation of Necessity

In Descartes theological writing, he promotes two jointly puzzling theses: T1) God freely creates the eternal truths (i.e. the Creation Doctrine) and T2) The eternal truths are necessarily true. According to T1 God freely chooses which propositions to make necessary, contingent and possible. However the Creation Doctrine makes the acceptance of T2 tenuous for the Creation Doctrine implies that God could have acted otherwise--instantiating an entirely different set of necessary truths. Jonathan Bennett seeks to reconcile T1 and T2 by relativizing modality to human understanding. I argue that Bennett’s approach to Cartesian modality is misplaced: One does not have to resort to conceptualism about modality in order to explain the subjective language found in Descartes or to reconcile Descartes’ Creation Doctrine with the necessity of the eternal truths. After showing that Bennett’s argument implies that Descartes held the non-eternality of the eternal truths and the independence of the eternal truths from God, I show that if one understands Descartes’ use modal terms as indexed to God’s willing, then apparent contradictions vanish. In addition, I show that if one evaluates the truth value of modal propositions ‘non-bivalently’, then one can also unravel the apparent contradiction. One can reconcile Descartes’ Creation Doctrine (T1) and the necessity of the eternal truths (T2) without Bennett’s conceptualis

The Effect of Mass Distribution on the Lateral Stability and Control Characteristics of an Airplane as Determined by Tests of a Model in the Free-Flight Tunnel

The effects of mass distribution on lateral stability and control characteristics of an airplane have been determined by flight tests of a model in the NACA free-flight tunnel. In the investigation, the rolling and yawing movements of inertia were increased from normal values to values up to five times normal. For each moment-of-inertia condition, combinations of dihedral and vertical-tail area representing a variety of airplane configurations were tested. The results of the flight tests of the model were correlated with calculated stability and control characteristics and, in general, good agreement was obtained. The tests showed the following effects of increased rolling and yawing moments of inertia: no appreciable change in spiral stability; reductions in oscillatory stability that were serious at high values of dihedral; a reduction in the sensitivity of the model to gust disturbances; and a reduction in rolling acceleration provided by the ailerons, which caused a marked increase in time to reach a given angle of bank. The general flight behavior of the model became worse with increasing moments of inertia but, with combinations of small effective dihedral and large vertical-tail area, satisfactory flight characteristics were obtained at all moment-of-inertia conditions