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UASystems eZELOS S4 Twin-Hybrid Air Taxi (concept design)

UASystems eZELOS S4 Twin-Hybrid hybrid-electric passenger helicopter concept design


eZELOS S4 Twin-Hybrid Air Taxi (concept design)
UASystems SA
Swiss Aéropôle, Payerne, Switzerland

Founded in 1995, UASystems SA (Uncrewed Aircraft Systems SA) is a Switzerland based company manufacturing unmanned multicopter drones, mission controllers, ultralight engines, mechanical subsystems, piloted, optionally piloted rotorcraft and more. They are currently working on their own full scale hybrid-electric vertical takeoff and landing (VTOL) passenger and air cargo aircraft for advanced aerial mobility (AAM). The company's slogan is Pursuit of the Future. The company is currently seeking investors, please contact the company using their website. (Image credit: UASystems SA)

The company's hybrid-electric VTOL aircraft can be flown in full electric mode, piston engine mode (direct drive) or in hybrid-electric mode. The company states that having three power sources on-board provides the maximum amount of flexibility, safety, range and flight time for their class of aircraft. By having two petroleum fueled engines, if one fails, the other engine can land the aircraft safely. If all power sources fail, the aircraft can autorotate to safety.

The company is developing a hybrid-electric free piston linear generator named the Beetron generator which can use natural gas, biogas, heating oil, gasoline, ethanol, hydrogen and solar synthesis gas to create electricity to power all electric motors and the aircraft's electrical systems. The engine is estimated to last for 20,000 hours. Their engine uses or has less parts, friction, weight, maintenance, fuel consumption, emissions and operational costs than traditional petroleum-only engines. The engine is used in conjunction with battery packs.

eZELOS S4 Twin-Hybrid Air Taxi hybrid-electric compound coaxial passenger concept design helicopter
The eZELOS S4 Twin-Hybrid Air Taxi is a futuristic piloted compound coaxial hybrid-electric concept design helicopter and carries one pilot and three passengers. The helicopter is powered by an internal combustion engine and has battery packs. Instead of using a transmission to turn the rotorblades, the rotorblades are turned by electric motors. Once autonomous systems are in place, that production aircraft will carry four passengers and no pilot. The aircraft has a target range of 500+ km (311 m).

Each main rotorblade has four blades and are in a coaxial configuration, meaning that one rotorblade is stacked on top of the other. The main rotorblades turn in opposite directions to counteract torque. There are two electric motors for each rotorblade for redundancy and if one or two electric motors fail, the other two will continue to power the rotorblades. It is also known that helicopters with coaxial rotorblades typically have a higher maximum payload, than helicopters in the same class, with only one main rotorblade. The helicopter also has two pusher electric ducted fans (EDF) located in the rear of the helicopter, on each side of the aircraft. Each ducted fan is powered by two electric motors for redundancy. If one electric motor fails, the other electric motor will continue to power the ducted fan. The company reports their aircraft is very stable even in strong winds.

The helicopter's windows provides good views for the pilot and passengers. At the lower front of the fuselage, there are stub wings with small winglets. Due to the helicopter having coaxial rotorblades, safety for passengers is increased greatly since there is no tail rotor on the helicopter. There is also a luggage compartment in the rear of the aircraft. The aircraft uses fixed-skid landing gear.

The company states the eZELOS twin-hybrid propulsion system produces 50% less carbon dioxide and has 60% lower operating costs when compared to light helicopters. eZELOS also requires less power storage in modern, long-lasting batteries. No downtime is required while charging the batteries in-flight and flight reserve time is maximized with their hybrid-electric power system.

Anticipated Missions and Technology Demonstrators
The company expects the eZELOS to be used for on-demand air taxi service, VIP service, air ambulance service, air cargo, security, police, coast guard, surveillance, offshore oil transportation, disaster relief and defense use. As of November 2022, the company was building a full scale technology demonstrator. The company announced in September 2023 that the first eZELOS technology demonstrator will be ready before the end of 2023.


  • Aircraft type: Hybrid-electric compound coaxial passenger concept design helicopter
  • Piloting: 1 pilot
  • Capacity: 3 passengers
  • Cruise speed: Unknown
  • Rotorblades: 2 coaxial rotorblades (4 blades per rotorblade)
  • Pusher propellers: 2 electric ducted fans (pusher ducted fans)
  • Electric Motors: 8 electric motors. If one or two of the electric motors for the main rotorblades fail, the other electric motors are built for redundancy and will help the helicopter land safely.
  • Power source: Hybrid-electric, piston engines and batteries
  • Fuselage: Carbon fiber composite
  • Windows: Standard helicopter windows
  • Wings: At the lower front of the fuselage, there are stub wings with small winglets
  • Tail boom type: The helicopter has no tail but there is a small downward facing vertical stabilizer protruding from the rear of the helicopter
  • Landing gear: Fixed skid landing gear
  • Safety features: In case of a power loss, the helicopter can land using autorotation. The company also has redundancy built into the aircraft providing an additional margin of safety.

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