Payload capacity, range and flight duration of a Unmanned Aerial System (UAS) depends mainly on thrust system. Thrust system of a typical electrical multi-rotor UAS consists of electric motors, rotors and electric speed controllers (ESCs). Electric motors are easy to use and their response time is short, which is highly desired and required for control, but they limit potential payload capacity, range and flight duration. In this paper, we propose a Quad-Jet VTOL (vertical take-off and land) UAS with a thrust system consisting of four mini jet engines. Such a vehicle could be useful heavy-lift applications. The UAS model, controllers, thrust direction system (to overcome the response time disadvantage and to improve motion) are presented, along with a first prototype system.