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SeaHorse Air SeaHorse H5 (concept design)

SeaHorse Air SeaHorse H5 passenger digital displacement hydraulic transmission VTOL concept design aircraft


SeaHorse H5 (concept design)
SeaHorse Air Limited
Edinburgh, Scotland, United Kingdom

SeaHorse Air Limited was incorporated on March 7, 2024 in Edinburgh, Scotland, United Kingdom. SeaHorse Air is a joint venture between FlowCopter in Edinburgh and Evdron in Singapore. The company is in the business of designing and developing a low flying amphibious five place vertical takeoff and landing (VTOL) aircraft that will be almost exclusively flown between coastal towns and islands. The company states the aircraft will typically only fly over water. The goal of their aircraft is to provide ferry service that is faster than the traditional ferry boat and that has luxury class pricing. (Image credit: SeaHorse Air Limited)

The company revealed their subscale mock-up to the public at Amsterdam Drone Week 2024 that took places April 16-18 in the Netherlands. The first aircraft model will use what the company calls "digital displacement hydraulic transmission technology" patented by FlowCopter. This technology is powered by internal combustion engines (ICE) that can be fueled by ethanol. In the future, the aircraft will be able easily be retrofitted to use electric motors and use a variety of power sources, such as hydrogen fuel cells or battery packs. At this point, the aircraft will then become a hybrid-electric VTOL aircraft for advanced air mobility (AAM).

SeaHorse H5 passenger digital displacement hydraulic transmission VTOL concept design aircraft
The SeaHorse H5 is a five passenger digital displacement hydraulic transmission VTOL concept design aircraft. The aircraft holds one pilot, four passengers and their luggage. The SeaHorse H5 has a boat hull due to the the market the company has slated for aircraft for coastal and island air ferry service.

The estimated cruise speed is 80 km/h (50 mph) and has an expected maximum speed of 120 km/h (75 mph). The anticipated range of the aircraft is 360 km (224 m) and has a planned flight time of three hours. The cruise altitude is foreseen at 15 m (49 ft) over the water. The empty weight of the aircraft is calculated at 550 kg (1,212 lb), with a maximum payload weight of 650 kg (1,433 lb) and has a maximum takeoff weight of 1,200 kg (2,645 lb).

The aircraft has eight propellers, powered by what the company calls digital displacement hydraulic transmission technology and will use an ethanol power source. The company calls the propeller assembly the rotor cluster tilt system. The propellers are on a cross brace structure that tilts forward and tilts back to a horizontal position to keep the fuselage as level as possible and to improve the efficiency of the propeller system and to provide a level ride for the passengers.

The fuselage will be made from carbon fiber composite material for a high strength and low weight ratio. The windows are larger than conventional aircraft providing excellent views for the pilot and passengers. The aircraft has several unique design features such as a boat hull, gull-wing doors, two sponsons, airstairs and an extendable gangway. The airstairs are usually used when the aircraft lands on a flat or ground surface. The extendable gangway (or boarding ramp) extends when the aircraft is floating in water and the gangway needs to extend to a dock, so passengers can easily enter or exit the aircraft. For landing on the ground or a hard surface, the aircraft has fixed tricycle wheeled landing gear.

All specifications on this web page are estimated. The actual flight specifications will be know when a pre-production prototype is made and is flight tested.

Future possibilities:
In the future, the company has stated the aircraft is able to be converted to use electric motors and use hydrogen fuel or battery packs for the aircraft's power source. The company will reconsider using electric motors and alternate power sources when battery density allows them enough power for long-range low-altitude travel over water. Meaning, the hybrid-electric or an all-electric power source would now be used to move the hydraulic fluid to turn the propellers.

SeaHorse H5 subscale mock-up, front view

SeaHorse H5 subscale mock-up, front view

SeaHorse H5 subscale mock-up, side view

SeaHorse H5 subscale mock-up, side view

SeaHorse H5 subscale mock-up, rear view

SeaHorse H5 subscale mock-up, rear view


  • Aircraft type: Passenger VTOL land and amphibious concept design multicopter
  • Piloting: 1 pilot
  • Capacity: 4 passengers and luggage
  • Cruise speed: 80 km/h (50 mph)
  • Maximum speed: 120 km/h (75 mph)
  • Range: 360 km (224 m)
  • Flight time: 3 hours
  • Cruise altitude: 15 m (49 ft) over water
  • Empty weight: 550 kg (1,212 lb)
  • Maximum payload weight: 650 kg (1,433 lb)
  • Maximum takeoff weight: 1,200 kg (2,645 lb)
  • Propellers: 8 propellers (rotor cluster tilt system)
  • Electric motors: Digital displacement hydraulic transmission technology (in the future, 8 electric motors)
  • Power source: Ethanol (in the future, hydrogen fuel cells or battery packs)
  • Fuselage: Carbon fiber composite, bottom of fuselage is a boat hull shape
  • Windows: Panoramic wrap around windows allowing forward, left and right visibility for spectacular views with a solid roof above the passenger compartment
  • Doors: Gull-wing doors
  • Landing gear: Fixed tricycle wheeled landing gear. The aircraft can land on the ground or water. The water landing portion of the aircraft has a a boat hull with two sponsons so the aircraft is stable in the water. When landed on the ground, airstairs open from the sponsons allowing passengers to enter and exit the aircraft easily. When in the water, the sponson can deploy a gangway (or boarding ramp) allowing passengers to walk from the aircraft to a dock and back.
  • Safety features: There are redundancies of critical components and in the sub-systems of the aircraft providing safety through redundancy. Having multiple redundant systems on any aircraft decreases having any single point of failure.

Company Insights:


Article: ADW2024: prototype Sea Horse Air five-person eVTOL "to fly later this year", Urban Air Mobility, Apr. 16, 2024