When we first came across Dr Carsten Mehring's StreetFlyer in 2011, its ride was described as like hang gliding on wheels. Like a hang glider, it didn't have a motor but relied on leg power and downhill slopes to get things moving. But now a student team at the Colorado School of Mines under Mehring's supervision has strapped a motor to the three-wheeled vehicle so it can be effortlessly ridden on the flat.
The E-Streetflyer is the same basic design as the original Streetflyer, with the user hanging suspended from a lightweight, arched frame. Users described the feeling of riding the original Streetflyer as like flying, with the sensation of speed heightened by the rider's proximity to the ground. The benefits of exercise aside, relying on hills or leg power on flat ground to propel the vehicle was still somewhat of a downside.
When we spoke to Mehring in 2011, he mentioned plans to develop a motorized version to overcome this problem and also help make it easier to push the vehicle back up a hill after cruising to the bottom. Feedback from users and interest from several amusement parks, including Disney, provided the motivation to follow through and create the E-Streetflyer.
The first motorized prototype is powered by a 750 W electric motor running off a 12 V lead acid battery and has an average speed of around 8 mph (13 km/h) when carrying a rider of around 180 lb (82 kg). However, a student testing the E-Streetflyer claimed the speed felt more like 10 to 15 mph (16-24 km/h), again, because of the close proximity to the ground. Mehring is aiming to increase the actual speed to around 20 to 25 mph (32-40 km/h) once the stability issues have been ironed out, which he hopes to accomplish by lowering the vehicle's center of gravity.
The current model can currently only climb 2 percent inclines so won't get a user up a steep hill unaided, which Mehring also hopes to address with a more complex gear box and by modifying the gear ratios. He is also considering alternative power sources and says that although a combustion engine would be the lightest solution, it would destroy the sense of effortless flying. For this reason, a proton exchange membrane (PEM) fuel cell stack is also being considered. Another possible change is switching from wheel-powered propulsion to a pusher propeller system.
Whatever shape the final design takes, Mehring is aiming to commercialize a motorized Streetflyer within the next two years and is working with a California-based e-bike business to try and develop a cost-effective production method. He is targeting recreational users, with amusement parks being a potential market.
However, he points out that the vehicle also has potential for patient rehabilitation in a similar way to the GlideCycle, but with the ability for the rider to position themselves in upright or laying down positions through the use of a different harness and frame.
The video below shows the current E-Streetflyer in action.