**10. Conclusions**

Here follow the several problems that affect this technology have been listed, as eventually exceeding these design, manufacturing and realization problems, for a device mass production.

• HYPERSONIC high-speed, supersonic (Mach 1–5) or hypersonic (Mach 5+) 15,200 m or

In the last decade, governmental incentives and the ever stricter emissions regulations have prompted some of the largest world automakers to dedicate resources to the study, design, development and production of hybrid vehicles, which offer undisputed advantages in terms of emissions and fuel consumption with respect to traditional, reciprocating internal combustion engines. In fact, hybrid engines are substantially smaller than conventional ICE, because they are designed to cover the vehicle's "average" power demand, which ensures proper traction for about 99% of the actual driving time, and is exceeded only for prolonged mountain drives and instantaneous accelerations. When excess power is needed above this average, the hybrid vehicle relies on the energy stored in its battery pack. Hybrid cars are often equipped with braking energy recovery systems that collect the kinetic energy lost in braking, which would be dissipated into heat otherwise, and use it to recharge the battery. Smaller sizes and an (almost) constant operational curve lead to lower emissions. Moreover, a hybrid vehicle can shut down completely its gasoline engine and run off its electric motor and battery only, at least for a limited operational range: this "mixed operation" increases the net mileage and releases a substantially lower amount of pollutants over the vehicle lifetime. The most popular hybrid vehicles (HV) are mostly passenger hybrid cars equipped with a traditional ICE and an electric motor coupled in parallel. The thermal engine is sized, with some exceptions, for the average power, and the surplus power needed during rapid

From the analysis of the several prototypes and from the documentation available in literature and on the web it can be noticed as all the groups of search are to the state of prototype. Regarding the prototype of the MIT they have been found problems of rotors failure in operating conditions. The group design by the Belgian researchers seem to be at the more advanced state, but they are not available data of any application. The Japanese model has been introduced to meeting a NATO and lacks recent news. For the Italian model the problem, currently resides in leading the system to a rotational speed, by means of generator/ electric motor, sufficient to prime the combustion. Problems have been found in

Here follow the several problems that affect this technology have been listed, as eventually exceeding these design, manufacturing and realization problems, for a device mass production.

• MALE (medium altitude, long endurance) up to 9,000 m and range over 200 km

• HALE (high altitude, long endurance) over 9,100 m and indefinite range

• CACGS Computer Assisted Carrier Guidance System for UAVs

• Tactical 5,500 m altitude, about 160 km range

suborbital altitude, range over 200 km • ORBITAL low earth orbit (Mach 25+) • CIS Lunar Earth-Moon transfer

**8.3.4 Range extender in hybrid vehicle** 

acceleration phases is supplied by the electric motor.

**9. Distance between state of art and goals** 

the bearings behaviour and their limited lifetime

**10. Conclusions** 
