HopFlyt is an enthusiastic young organization devoted to renewing the Custer Channel Wing, a lost remnant of attempts to create extremely short takeoff and landing (STOL) airplanes starting over 70 years ago. Their web site explains their primary goal, which includes adding electrically-powered vertical takeoffs and landings to the channel wing’s repertoire. “HopFlyt is an aviation technology startup company [whose] main priority is to develop technology and ultimately build a sustainable electric Vertical Takeoff & Landing (eVTOL) aircraft. The goal of this aircraft is to help you beat the jam of traffic and reduce pollution in major urban centers around the world. We want to change your 2 hours of traffic into a short 20 minutes of flying.”
Willard Custer’s Frustrated Search for High Lift
Willard Custer designed several approaches to using his unique ducts to channel air around the rotating propeller. These are covered in at least 27 patents granted to him between 1929 and 1974. He built and flew three aircraft, CCW 1, CCW 2, and CCW 5 all of which were twin engine, from 1940 into the mid-1950’s.
Early demonstrations for the military showed his semi-circle wing surrounding a propeller could draw enough air through the “channel” to pull the airplane off the ground with no forward motion of the airplane (not mentioning the wind speed during the test). A French web site devoted to the channel wing describes this test. “Willard decides one day to demonstrate the vertical flight of his device. Attached to a rope stretched between two masts, the machine is indeed rising … naturally, hardly the engines set in motion.” Custer claimed flight at speeds as low as eight to 11 mph with this CCW-2.
His later CCW-5 was a four-seater equally capable of STOL performance.
Its twin 225-horsepower engines certainly produce enough noise to be unwelcome guests at most airports today, and not likely to be approved for neighborhood airparks or rooftop arrivals and departures. Perhaps electric propulsion can help solve part of the noise issue.
Custer’s experiments received a great deal of public interest and comment, and even tests in the NACA Langley wind tunnel, but no “takers” for certification and production. High drag associated with the extreme STOL capabilities kept the airplane in lower speed ranges – but that’s not a problem for HopFlyt’s innovators.
HopFlyt’s Vertical Extension of Custer’s Ideas
HopFlyt’s mission limits trips to under 200 miles, so high cruising speeds will not be as important as the fact that commuters will avoid the gridlock below.
“At HopFlyt, we are designing an electric Vertical Takeoff & Landing (#eVTOL) aircraft that allows you to fly over the traffic, saving you precious time, so you can be more productive. Additionally, HopFlyt is exploring ways to reduce recurring energy costs and make urban transportation fast, safe and sustainable.”
The design combines tandem wings, eight electric powerplants, and eight channels surrounding multiple-bladed propellers to provide thrust. With the wings pivoted perpendicular to the fuselage, the airplane can make vertical takeoffs.
HopFlyt aims to make their craft accessible to all, with one possible means to achieve this being the use of automated manufacturing. Their video of a 1/7-scale wing rib being 3D printed shows at least one possible way to achieve their goals.
Although there is little in the way of detailed specification at this time, it’s interesting to see the revival of Willard Custer’s dream.