|An autocad model provided to EAA of the current configuration for Rutan's latest design, the Bipod.
|The Bipod, in driving configuration.
Photos courtesy of Burt Rutan
Burt Rutan took the lid off his latest project, the BiPod, at a homebuilders chat this morning, and it looks different than images released last week by Scaled Composites, Burt’s former company that owns the design.
“I didn’t ask Scaled if I could give this talk, but since I read about it in Aviation Week, I think it’s okay,” Burt said.
The first images of the BiPod included CAD drawings with four propellers—one on each wing and two on the horizontal stabilizer between the tails of the twin-fuselage, hybrid-electric roadable aircraft.
“The most recent version had the propellers only on the tail, not on the wings,” Burt told EAA last week. “So you don’t handle the propeller and have to unplug the electric connection to move the wings [and stow] in between the body.”
The current configuration also includes a forward tie bar canard fairing, Burt said. Although this version isn’t documented in pictures, his son, Jeff, created CAD drawings from information Scaled provided.
Unlike Terrafugia, which transitions from a car to a plane with the touch of a button, the pilot will have to get out of the aircraft to stow the wings on brackets underneath the BiPod.
“It was designed to have a 10-minute, no tools, single-person changeover,” Burt said. “The wing weighs only 50 pounds, so you can pull it out and it has a skateboard wheel on the wing spar. So then you walk around and treat it like a wheel barrow. A single person can position it between the bodies and get up and snap it into place.”
Burt was excited that it is a STOL aircraft with very high wheel power plus prop power. This will allow it to take off from a clearing or a road somewhere without having to use an airport. He also noted the aircraft has very large baggage compartments.
“You could put golf clubs and soft luggage and even skis in it. It’s long,” Burt said. “You know there is nothing back behind the pilot except for things that are low, like the gas engines and the wheel.”
Only the first phase of the prototype has been completed, and Burt is unsure whether Scaled Composites will continue development. “Phase one is what I sold back in November to Scaled management to go ahead and company-fund just the part of the car that has electric drive,” he said.
Phase one testing was focused on determining whether it is a safe car, Burt said. “It has driven at 80 mph with a 35-knot crosswind. It’s a good, safe car.”
It is powered by lithium iron phosphate batteries, which are the same type of batteries that are in the Toyota Prius. However, these are larger.
“It’s also flown just with wheel power launching it,” Burt said. “It looks like a very good flying airplane, although it doesn’t have many hours in the air, as you might imagine.”
The plan for phase two, if Scaled finds a customer willing to invest in the project, is to put in the gas engines that drive nothing but generators and to put in the propellers.
It is designed for two 450-cc internal-combustion engines, one in each fuselage, powering generators supplying electricity to four 15-kW motors producing 20 hp—one in each pod driving the wheels, and two on the horizontal stabilizer linking the twin tails. Additional power on takeoff is provided by lithium batteries in the nose that are recharged in flight, providing enough power for two landings in the event of an engine failure.
The aircraft is flown from the right fuselage, where flight controls are located, and driven from the left, which houses a steering wheel. The cockpits are connected through the center wing, which also holds an 18-gallon fuel tank. The wingspan is 31.8 feet; in the car configuration it’s 8 feet wide.
On the ground the BiPod’s aft wheels are driven by 15-kW motors, and the nose wheel in each fuselage is steerable. It was designed to drive 820 miles at 65 mph on a tank of gas and 35 miles on the batteries alone, with the ability to reach highway speeds, although Burt said those numbers may change.
The BiPod taxis as a car and starts takeoff roll without the propellers running. The pilot will then advance the propeller throttle to achieve rotation in about eight seconds. In the air, it is designed to cruise at 197 mph with a range of 530 miles at 12,000 feet in a higher-power mode, and up to 760 miles at 100 mph at 8,000 feet. The expected gross weight is 1,430 pounds with two passengers and fuel.
While Scaled is looking for a customer to fund phase two of the project, don’t expect Burt to sit idle in his new Idaho home.
“I’ve done a new type on average one a year since 1973,” Burt said. “Do you think I can stop that?”