Abstract. This paper deals with the analysis of vehicles capable of travelling dead downwind or dead upwind faster than the wind. Vehicles powered by traditional sails can reach velocities larger than the wind speed, but they are not capable of doing that travelling directly upwind or directly downwind, this type of vehicles reach their best performances maintaining a course angled compared to the wind direction. In order to travel directly upwind and to try to go faster than the wind both dead upwind and dead downwind vehicles employing a rotor may be used. Despite the fact that the testing of this type of vehicle has been documented since the mid of the 20th century a complete analysis of factors influencing performances of this type of vehicle is not available. This paper represents a first attempt to fill this gap. The paper is divided in 2 main sections, the first section is introductory and it contains a discussion concerning the meaning of the sentence “faster than the wind” this discussion allows to establish differences existing between traditional sail powered vehicles and rotor powered vehicles. The second section is devoted to the analysis of latter type of vehicle and can be divided in 4 parts. The first part is focused on the identification of all possible configurations of motion that can be obtained as a function of how the rotor may be connected to the wheels. The second part deals with the analysis, for the two configurations identified in the first part, of the dynamic conditions leading to the start of the motion in the downwind or in the upwind direction. The third part, in order to investigate the sustainability of the initial motion, focus on the derivation of equations of motion for the configurations described. The forth part, in order to investigate the capability of the described configurations to reach velocity larger then the wind speed, analyze the evolution of the apparent velocity acting on the rotor blades. Finally some considerations concerning the optimization of the vehicle design are presented.
FASTER THAN THE WIND: ANALYSIS OF ROTOR GEARED VEHICLES
Bovolin V
2017-01-01
Abstract
Abstract. This paper deals with the analysis of vehicles capable of travelling dead downwind or dead upwind faster than the wind. Vehicles powered by traditional sails can reach velocities larger than the wind speed, but they are not capable of doing that travelling directly upwind or directly downwind, this type of vehicles reach their best performances maintaining a course angled compared to the wind direction. In order to travel directly upwind and to try to go faster than the wind both dead upwind and dead downwind vehicles employing a rotor may be used. Despite the fact that the testing of this type of vehicle has been documented since the mid of the 20th century a complete analysis of factors influencing performances of this type of vehicle is not available. This paper represents a first attempt to fill this gap. The paper is divided in 2 main sections, the first section is introductory and it contains a discussion concerning the meaning of the sentence “faster than the wind” this discussion allows to establish differences existing between traditional sail powered vehicles and rotor powered vehicles. The second section is devoted to the analysis of latter type of vehicle and can be divided in 4 parts. The first part is focused on the identification of all possible configurations of motion that can be obtained as a function of how the rotor may be connected to the wheels. The second part deals with the analysis, for the two configurations identified in the first part, of the dynamic conditions leading to the start of the motion in the downwind or in the upwind direction. The third part, in order to investigate the sustainability of the initial motion, focus on the derivation of equations of motion for the configurations described. The forth part, in order to investigate the capability of the described configurations to reach velocity larger then the wind speed, analyze the evolution of the apparent velocity acting on the rotor blades. Finally some considerations concerning the optimization of the vehicle design are presented.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
