The Slepcev claims of 15mph flight are exaggerated.
Quote from website: "The aircraft will fly at 22mph at full flap and 30% of power. Take off run into a 16mph wind is vertical with no forward roll".
So what is the stall speed, 22mph or 15mph?
They can make any claim they want using indicated airspeed. I had an airplane that would indicate 0 mph in a steep climb.
The engine can provide lift for takeoff, but using full power to reduce the landing speed is not practical. That's why the landing distance is longer.
slowrotor