ON PROPULSIVE EFFECTS OF 

 A ROTATING MASS 



Prof. Alfio Di Bella 



Instituto di Architettura Navale 



University of Genoa 



Genoa, Italy 



ABSTRACT 



This paper is dedicated to the study of particular rotatory motions of 

 masses in space. ^ 



It is demonstrated experimentally that, within certain limits, small mo- 

 tions in the desired direction of a vehicle can be obtained by placing 

 within it a mass that is kept rotating by a motor. The devices that were 

 used are described and a full summary of the results that were obtained 

 is given. .. ,,,•.. . ,, 



We have pointed out what, with certain difficulties overcome, will prob- 

 ably be the most important application of these devices: on certain 

 types of ships, to give them forward or backward motions, lateral and 

 evolution motions, at low speeds; in automobiles, to create in them lat- 

 eral motions which would be useful for parking, in forward and back- 

 ward motions, and in changes of the direction of motion. 



DESCRIPTION OF THE TESTED DEVICES 



In January 1962, we proposed to initiate a study on the rotatory movement 

 of a mass in space, to see if the dynamic actions produced by it could make 

 way for possible applications in the field of propulsion. We decided to begin 

 by considering the rotatory motion of a mass around a point. 



The device indicated in Fig. 1 immediately appeared useful to our study. 

 It executes the motion of a point on a hemisphere. With simple mechanisms, 

 it was possible to have an arm ap = r , rotating around a point 0, having the 

 extremity A coincide with o, and the extremity p free to move on the hemi- 

 sphere. A mass m was concentrated in P. 



As a matter of interest, it is recalled that the trajectory described by P 

 belongs to the hypopedes family, studied in astronomy by Eudoxus, a contempo- 

 rary of Plato. More precisely, the trajectory represents the window of Viviani, 

 a pupil of Galilei, who posed the problem of tracing four windows of maximum 

 area on a hemisphere. (The solution of the problem, given by Gauss, requires 



1373 



