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chAIR Multicopter

chAIR Multicopter
Orebro, Sweden

This multicopter was designed by Axel Borg from parts he got from Hobby King. The design is an all electric Vertical Take-Off and Landing (VTOL) or eVTOL aircraft and features a central seat surrounded by four (4) circular rotor-mounts holding 19 propellers each, for a total of 76 propellers for the entire aircraft. The estimated flight time is 14 minutes, but the maximum attempted time is 11 minutes. The estimated build cost was $10,000.

His first manned flight for the chAIR Multicopter with the four (4) circular rotor-mounts was in 2017. He originally built an eight (8) rotor one (1) person VTOL which was powered by a eight (8) engines placed directly under each propeller.

Components pre-2019:

  • Control Board: KK 2.1 Multi-Rotor Control Board
  • Motors: Multistar Elite 5010-274KV Multi-Rotor Motor
  • ESC: 76 afro 20A HV, with one extra 63V 330uF low ESR capacitor, fitted to each ESC to handle the long current path from the battery to ESC.
  • Batteries: 80 Multistar 4S 5.2Ah
  • Controller: RC 5x Turnigy TGY-i6S Digital Proportional Radio Control System

In April 2019 more test flights were flown. You can watch these flights using the links below, they are Episode 31 and Episode 32. His eVTOL multicopter, in 2019, continues to have 76 propellers, 76 electric motors, 80 batteries (according to his specs), one seat within a metal boxed shaped frame, and has other electronic equipment for flight and navigation purposes. When one disassembles the circular rotor mount for storage and then take it out and fly it again, it takes about 15 minutes to reassemble the aircraft for flying. He uses multiple Kevlar ropes to attach each circular rotor mounts to the chair.

When viewing the videos, one notices that the four (4) circular rotor-mounts rest on the ground and then when the engines are started, the 4 rotor-mount frames rise and stay fairly horizontal due to the restraining ropes. Alex talks about the maximum safe speed being around 50 kmh (31 mph) because when he pushes the aircraft to go faster, he feels the 4 circular frames beginning to shake and won't push the limits of his aircraft.

Some Details From DIY Episode 32 video, April 20, 2019:

  • Maximum safe speed 50 kmh (31 mph)
  • 163 kg (360 lbs) TOW (Take-off weight)
  • 35 kg (77 lbs) LiPo currently mounted on the craft. (LiPo = Lithium polymer battery)
  • Typical hover efficiency: 7.5-7.7g/W
  • Flight Controller Board: Quantity (5) KK 2.1 running stock 1.6 firmware
  • Motors: Quantity (76) Multistar Elite 5010 274Kv
  • Electronic speed controller: Quantity (76) afro 20A HV, with one extra 63V 330uF low ESR capacitor fitted to each ESC to handle the long current path from battery to ESC. (ESC = Electronic speed controller)
  • Batteries: Quantity (80) Multistar 4S 5.2Ah
  • Radio Control: RC 5x Turnigy TGY-i6S Digital Proportional Radio Control System
  • All of the above purchased from Hobby King. Located in Hong Kong, China with branches in multiple countries.
  • Total cost: Approximately $10,000.00 USD