Bivect Air Twister (concept design)

(Image credit: Bivect Air)

Twister (concept design)
Bivect Air, Inc.
Sainte-Marie-Saint-Raphaël, New Brunswick, Canada
www.gary-gress.pixels.com

Gary Robert Gress, a Canadian mechanical engineer and lifelong aviation innovator is the sole principal of Bivect Air. Gress has has developed multiple two propeller passenger electric vertical takeoff and landing (eVTOL) for advanced air mobility. His approach to aircraft design blends decades of aerospace engineering experience with a deep curiosity for vertical takeoff and landing (VTOL) history—from early helicopter concepts to modern gyroscopic control systems. Gress has participated in both the GoFly and GoAERO competitions.

Some background information about Gress
After retiring around 2012, he returned to school to complete his M.Sc. and Ph.D. in Mechanical Engineering at the University of Calgary, with the goal of fully understanding the control of hovering aircraft. His design teacher, who was not in the aerospace industry, taught Gary an invaluable lesson that has spurred him to continue even when he confronts seemingly insurmountable barriers. He once said to the class: "It takes a lot of work to make something simple," he remembers. "I think that is so true and it applies everywhere.," Gress said.

Transitioning eVTOL Aircraft with Augmentative Cross-Modal Elements White Paper
Gress presented "Transitioning eVTOL Aircraft with Augmentative Cross-Modal Elements" at Forum 80, sponsored by the Vertical Flight Society, May 7–9, 2024, Montréal, Québec, Canada. His proposition boiled down, is that two propellers are the right amount of propellers for an eVTOL aircraft with respect to weight and drag considerations. That is, each addition propeller increases weight and drag for the aircraft. In addition, Gress states that two propellers are sufficient for hovering due to what is called active tilting. Active tilting involves the use of the propellers’ gyroscopic, momentum-wheel and drag-torque moments which keeps the aircraft stable during hovering. Three of several aircraft that he cites in the paper are his own prototype aircraft, the AW609 tilt-rotor and the Agusta-Westland Project Zero.

Twister passenger eVTOL multicopter (concept design)
The Twister is a one passenger eVTOL multicopter aircraft for recreational or personal use. The aircraft is planned to be piloted and used for medium range trips. The pilot sits in an open cockpit. A subscale model of the aircraft was made by the inventor.

The estimated cruise speed 142 km/h (88 mph) with a predicted range of 72 km (45 miles). The aircraft has two shrouded counter-rotating propellers which tilt in all directions, has two electric motors and is powered by lithium-ion batter packs. The empty weight of the aircraft is calculated to be 234 kg (515 lb), with a projected payload weight of 91 kg (200 lb) and has a forecasted maximum takeoff weight of 325 (715 lb). There are small stub wings on the aircraft increasing its cruise speed and range. The fuselage is made from carbon fiber composite to give the aircraft a high strength to low weight ratio. The aircraft has short fixed skid landing gear.

Specifications:

• Aircraft type: Passenger eVTOL multicopter (concept design)
• Piloting: 1 pilot
• Cruise speed: 142 km/h (88 mph)
• Range: 72 km (45 miles)
• Empty weight (including battery weight): 234 kg (515 lb)
• Payload weight: 91 kg (200 lb)
• Maximum takeoff weight: 325 (715 lb)
• Propellers: 2 shrouded propellers (counter-rotating propellers which tilt in all directions), 4350 RPM
• Electric motors: 2 electric motors, shaft power 78 kW each
• Power source: Li-Ion batteries, 91 kg (200 lb)
• Fuselage: Carbon fiber composite
• Wings: Stub wings
• Window: Open cockpit
• Landing gear: Fixed skid landing gear
• Safety features: Distributed Electric Propulsion (DEP) uses multiple propellers or electric ducted fans, each powered by electric motors, to increase safety through redundancy. If one or more components fail, the remaining ones can still ensure a safe landing. There are also redundancies of critical components 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. Has shrouded propellers for additional safety.

Related Aircraft:

• Bivect Air Air Rider (concept design)
• Bivect Air Ariel (concept design)
• Bivect Air Nymbus (concept design)
• Bivect Air Odyssey (concept design)
• Bivect Air Rogue (concept design)
• Bivect Air Tandem-X (concept design)

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Resources:

• Gary Robert Gres website
• Gary Robert Gress Facebook
• Gary Robert Gress YouTube
• Gary Robert Gress LinkedIn