VERTOL is a costly proposition and all rotary-winged aircraft are far less efficient than their fixed-wing counterparts. So it wold take a quantum leap in battery technology to give this thing range anywhere near what a small private airplane has.
The four pairs of contra-rotaing rotors is smart because each rotor in each individual pair cancels the torque from its partner. There still will be some twisting about the engine mount but that is canceled by the twisting from the pair diagonally opposite. Net torque about the airframe is nil, so there’s no need for anti-torque controls.
And it saves weight and simplifies the flight controls because all that ever changes is the amount of electric current going to an individual motor. Conventional helicopter rotors spin at a constant rpm and change how much lift they’re producing by changing the rotors’ angles of attack, sometimes all around all at once (collectively) and sometimes just in one area (cyclically) to make the helicopter bank left or right, or to pitch nose up or pitch nose down. This requires a swash plate and pitch change tubes and all the associated bellcranks, gears and pulleys and whatnot.
This does the same thing by simply changing the voltage being sent to each individual motor. Increase the electricity to the four engines on the right (or decrease same to the four on the left) and it banks left. Pitch remains the same and the rotors just spin faster or slower.
Using electric motors makes the contra-rotating pairs much more compact than they could be with an ICE engine because you don’t have to accommodate a drive shaft or all the components in a conventional rotor head. Eight electric motors is the heart and soul of its redundancy, which is indispensable in a design like this because if you don’t have pitch control you can’t autorotate.
Overall this is a brilliant design that accounts for most any failure you can think of, including a ballistic parachute for sudden loss of power or catastrophic mechanical failure. And parachutes aren’t much good in a conventional helicopter because the fan up top would shred your parachute first, then you.
And if Loz Blain thinks building your own aircraft gets you out of having to get a license, he’s an idiot. If it can meet the FAA’s definition of an “ultralight” it might not require licensing, but not because it’s home-made.
The solution to the problem of evtol flight time is to make them hybrids. Keep just enough LIon batteries to smooth out the peaks and valleys of the electric drive motors ramping up and down for flight control. Then use a very light weight gas turbine driven turbo alternator and SCR rectifier to push high voltage DC current into the Lion and evtol drive train. A small gas turbine can ramp from 10% to full output in under 4 seconds so that’s how much buffer time the battery pack needs to smooth out. A compact wankel rotary with a similar power to weight ratio of a gas turbine can ramp from 10% to 100% in under a second as long as it’s already spinning at its max output rpm under light throttle. Rotarys are like gas turbines in that regard they have such little inertial mass in the rotors as soon as the throttle is opened WFO they are putting put max output. Nothing to spin up just more combustion gas through the rotors. With the density of JetA vs Lion batts hundreds of miles if flight range could be had for the same takeoff mass. Even including the turbo alternator and generator. Turbines are are 6hp per lb of mass or better. High speed alternator are upwards of ten kw per lb of mass, and the SCR rectifier would be a few kg for a 100kw sized rectifier. All the other mass saved over batteries is for JetA at 38 kWh per gallon in raw energy. Even at 30% efficient in converting JetA to electrons that’s still over 10 kWh per gallon of fuel. One gal JetA is 6lbs ish an order of magnitude greater total.energy density vs batteries.