Bivect Air Tandem-X (concept design)

(Image credit: Bivect Air)

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

Led by Canadian engineer and lifelong aviation, innovator Gary Robert Gress of Bivect Air has developed a tandem-propeller Emergency Response Flyer designed for rapid deployment, direct patient access and stability in challenging environments for the GoAERO competition. For the competition, Gress found inspiration from an unlikely pop culture source, M*A*S*H, the Korean War-era mobile army surgical hospital (MASH) depicted in the award-winning film and TV series.  The Tandem-X is the eVTOL aircraft that he submitted to the GoAERO Stage 1 competition.

Gary's approach to aircraft design blends decades of engineering experience with a deep curiosity for vertical takeoff and landing (VTOL) history—from early helicopter concepts to modern gyroscopic control systems. His flyer, Ariel, reflects that vision: compact, transportable and built to reach places traditional aircraft can’t. While Team Bivect Air participated in the GoAERO competition, the team was unfortunately not a Stage 1 or Stage 2 winner. He plans to enter the GoAERO Stage 3 contest.

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.

Tandem-X White Paper
Gress wrote a 19 page White Paper for the Tandem-X emergency rescue eVTOL aircraft titled the "Tandem-X, an Emergency-Response Flyer" for the GoAERO State 1 competition.

Tandem-X emergency response passenger eVTOL multicopter (concept design)
The Tandem-X is an emergency response passenger eVTOL multicopter aircraft created for the GoAERO Phase 1 competition. The aircraft hold one pilot and is either an autonomous or remote controlled aircraft. The eVTOL aircraft has a canopy over the cockpit. The aircraft has arrow-shaped lifting fuselage with variable-swept wings to allow longer and faster flight. The aircraft is able to be transported by a highway legal trailer or large pickup truck and able to fly to and back from a rescue zone.

The cruise speed of the aircraft is estimated to be 164 km/h (102 mph). The flight time varies depending upon the payload weight. For example, with a 57 kg (125 lb) payload weight, the aircraft has an 18.3 minute hover flight time. For forward flight, with the same payload weight, the aircraft can fly 82.1 minutes at a speed of 164 km/h (102 mph). The multicopter has two tandem configured fixed-pitched counter-rotating propellers on gimballed mounts and can be actively tilted in all directions by servos for all directions of flight including hover and forward flight. There are two electric motors and and are powered by lithium ion batteries.

The empty weight of the aircraft is expected to be 125 kg (275 lb). The anticipated maximum payload weight of the aircraft has a range of 57-145 kg (125-320 lb). The fuselage is made from carbon fiber composite to give the aircraft a high strength to low weight ratio. The aircraft has fixed quadricycle strut landing gear.

Gress not only created detailed concept design drawings with aeronautic mathematical formulas but he has also made a subscale prototype of the rescue aircraft.

About the GoAERO Prize Competition
The GoAERO Prize, sponsored by Boeing, is a three year competition (2024-2027) offering over $2 million USD in prizes that challenges engineers worldwide to create portable, versatile and autonomy-enabled Emergency Response Aircraft that address not only everyday medical emergencies but also to be used in natural disasters, humanitarian emergencies and climate crises worldwide. Each team designs and builds autonomous Emergency Response aircraft capable of delivering a first responder, medical equipment and supplies and ultimately evacuating victims in need to a rescue ambulance or hospital.

More than 150 teams from around the globe are competing for the GoAero prizes. The GoFly and GoAERO prizes were developed by Boeing and other organizations to help the nascent advanced air mobility (AAM) industry move forward.

Specifications:

• Aircraft type: Emergency rescue passenger eVTOL multicopter (concept design)
• Piloting: Autonomous or remote piloting
• Capacity: 1 passenger
• Cruise speed: 164 km/h (102 mph)
• Flight time: 18.3 minute hover with a 57 kg (125 lb) payload. 82.1 minutes with a 57 kg (125 lb) payload traveling at 164 km/h (102 mph).
• Empty weight: 125 kg (275 lb)
• Maximum payload weight: 57-145 kg (125-320 lb)
• Propellers: 2 shrouded propellers (counter-rotating propellers which tilt in all directions)
• Electric motors: 2 electric motors, 60 kW rate each
• Power source: Li-Ion batteries, 160 kg (350 lb)
• Fuselage: Carbon fiber composite
• Window: Canopy over the cockpit
• Wings: Arrow-shaped lifting fuselage with variable-swept wings
• Size of aircraft: 2.56 m W X 4.88 m L (8.5 ft W X 16 ft L)
• Tail: 2 horizontal stabilizers
• Landing gear: Fixed quadricycle strut 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 Twister (concept design)

Company Insights:

• Bizapedia

Resources:

• Gary Robert Gres website
• Gary Robert Gress Facebook
• Gary Robert Gress YouTube
• Gary Robert Gress LinkedIn
• Article: GoAERO Global Emergency Response Flyer Competition Announces $500,000 of Awards to Innovators Worldwide with Support from Boeing, NASA, RTX, and Honeywell, GoAERO, Feb. 18, 2025
• Article: GoAERO Competition Promotes Creation of Automatic Lifesavers, Flying Magazine, Nov. 17, 2025
• Article: Meet the Teams: Team Bivect Air, GoAERO, Nov. 26, 2025