Carlo Casarosa

Impact of safety requirements on the weight of civil unmanned aerial vehicles

The lack of airworthiness and certification criteria for the employment of UAV vehicles in the civilian field has caused an uncontrolled proliferation of projects and the construction of a number of UAV prototypes which differ in dimension, weight, flight characteristics and payload carriage. This paper is aimed at identifying the most important project criteria which may concur to unifying the main UAV characteristics. In particular, the minimum take‐off weight is investigated which is able to guarantee the adherence to the levels of safety required by the airworthiness design requirement (ADR) currently being developed. To this end, the characteristics of mission and the safety requirements currently available in the ADR have been examined. and the safety characteristics and reliability of the UAVs used in the military field have also been considered. After which, an assessment is made of the on‐board system and the relative redundancies necessary for adjusting such characteristics to meet the ADR. Taking into account the weight of systems, payload and other UAV components (engine, structure, etc.), a reasonable estimation of the take‐off weight as well as the geometrical dimensions of a certifiable UAV are obtained.

Rate of Growth of Population and Aggregate Saving in the Basic Life-Cycle Model

In this paper we explore the impact of the life-cycle dynamics of family composition on the aggregate propensity to save and on the relationship between the latter and the rate of growth of population, in the hypothesis of life-cycle behaviour. We depart from Modigliani-Brumbergs basic model by assuming that the household, rather than the individual, is the relevant economic unit. In this framework we point out that in an economy with a steadily growing population the aggregate propensity to save is a function of several demographic parameters and, in particular, of the timing of births (T) and of the number of children generated by each household (f). We then explore the impact of T and f on the co-movements of the rate of growth of population and of the aggregate propensity to save. We show that, when the change of the rate of growth of population is brought about by a change of the number of children generated by each household, the aggregate propensity to save and the rate of growth of population move in the same direction, as suggested by Modigliani-Brumberg, unless the timing of births is very low and the number of children generated by each household relatively high. On the contrary, when the rate of growth of population changes because the timing of birth changes, the aggregate propensity to save and the rate of growth of population move in opposite directions unless the number of children generated by each household is very close to two and therefore the rate of growth of population very close to zero.