It takes 5 minutes to refuel a helicopter with liquid fuel, and it is good for another 2-3 hours. Refuel, 2-3 hrs work, and so on.

It takes overnight to recharge a battery pack, and it is good for maybe 45 minutes. Then on the ground till recharged, or have another massive, heavy and expensive battery pack to swap out.

A quantum leap in energy density in batteries is needed for it to happen for a USEFUL human-carrying machine.

And don't forget, even Elon Musk can't change the laws of physics: to propel an object into the air will always take the same number of electrons and it takes time and infrastructure to put electrons into batteries, even if there is a quantum leap in energy density of batteries.

With a single onboard charger on a Model S Tesla, being charged from a normal (US) 110V outlet, you get 5 miles of range for every hour of charging. From 0 to 300 miles of range takes 52 hours.

Given the inevitable safety margins required for an electrically powered helicopter, I cannot see it ever being a practical proposition.

Just put the batteries in modules. Drop the spent one and take some fully loaded one instead. No need to wait for charging.

so, those ladders to get in and out?
do I need to FedEx them to every location I plan on landing at to arrive before I do?

Electric Helicopter
Oskar Stielau
Auckland, New Zealand

During September 2019, inventor Oskar Stielau, based in Auckland, New Zealand, started the development of an experimental electric helicopter. He starting formulating the idea of building an electric helicopter in 2014. The helicopter model is a conventionally powered Mosquito helicopter which he built in 2008 and Stielau flew as a gas-piston engine helicopter for 60 hours. The rotorcraft has now been completely converted into an electric helicopter.

https://evtol.news/stielau-electric-...SeTma7kmT2vMDQ

.

Video of the Oskar Stielau Electric in flight .... and demonstrates an auto.

In a real auto, as a result of electrical failure, there will be no tail rotor operating, as it is run by a potentiometer adjusting electric power to the 7 rotors.
In a real auto, will the dead electric motor drag the RRPM down, or is there a freewheel unit?
In a real helicopter, they keep the electrics where they belong, in batteries and generators, not running the show.

This guy's work is impressive. A bit simplistic, obviously, but still quite well thought out. It would not take a lot of extra work to make the electric power source for the main and tail rotors fully redundant. Going to an even number of tail rotor motors makes this trivial, just split them half and half. For the main rotor motor slightly less trivial as actual power electronics would be involved but nothing that hasn't been done before in many other applications. One might even consider two motors but that starts to generate the usual diminishing returns in terms of cost/complexity/size/weight.

Even the 27 minute endurance is impressive given the limitations of today's battery technology. It is, unsurprisingly, very commensurate with drones of all sizes. Stating the obvious, until someone comes up with electrical power storage systems with approx. 10 times the power density currently achievable, prime power will continue to derive from piston and turbine sources, even if some of that power is converted to electrical energy for an electric anti-torque system. And that also does not address the problem of charging time.

For me the real take-away is that, looking at this effort, and Bell's work also, electric anti-torque systems using a multiplicity of rotors/motors clearly seem to be the future. No drive shafts. No gearboxes. With appropriate design, a much higher degree of failure tolerance and safety. Improved authority. Less noise. Less maintenance. With proper engineering, what's not to like about it? A bigger alternator, a small battery backup, a two channel control unit, and none of this is rocket science anymore.

I have followed Oskar's testing for a while now
I believe he uses the original Mosquito helicopter freewheel unit

He was very thorough , all his initial testing was tethered flight , measured lift and thrust and electric consumption in all parameters.

He demonstrated an auto in the video ... how can anyone say it will not auto ??
Yaw control would not be lost if main electric motor failed
Loss of yaw control would require total battery failure ... big difference.

Beloved Billion dollar Sikorsky engineers built an all electric Hughes 269
But did not show it actually flying

Home built experimenter Oskar built one from his grocery money
And it actually flies.
Big difference

Correction: BBDSEs outsourced the build of an all electric Schweizer 300 and it never flew. Maybe they outsourced it to the wrong people. Or maybe they should have not oursourced it, and used the project to develop their young talent like we did on X2.

I think the future of the helicopter is definitely electric, but it will take time. All of the drive and control technology exists and has done for decades in some instances. The obvious missing ingredient is electricity storage. Until we can store electricity in a much more energy-dense fashion electric helicopter will not be truly viable technically or more importantly commercially for operators.

Hybrid gas turbine generators might be an intermediate step, but it would take a smaller manufacturer or startup to do this cost effectively, the big boys would bring all their friends to the party and make it too expensive.

Dont fear the coming of electric drive, it will make helicopters better for all of us. Similarly, don't fear the eVTOLs, a modern electric helicopter would out perform them all.

I shall miss the startup sound of a Rolls Royce engine though.

cran

he demonstrated a descent to a flare and a power recovery - was it actually in auto? What would be better proof is a full touchdown auto.

In the other video he hasn't learned how to prevent sink at the end of a quickstop either and seems blissfully unaware of the proximity of his tail to the ground.

Don't get me wrong, I admire what he has done but he is only a small part of the way there.

Outside of specific applications we aren't going to see a plugin helicopter any time soon, we are still too far away from getting light-weight, efficient power storage.

Hybrids, on the other-hand, is a more interesting area.
The use of motors to power the tail rotor (ala Bell EDAT), or for supplemental and emergency power requirements are more practical uses.
In mainstream applications, the integration of electrically driven systems will be more evolution than revolution.

Nice to have autorotation as a backup in the event of a main power bus failure vs. becoming a brick with a multirotor.

The smaller the aircraft , the better electric works (drones etc) .... much larger and results diminish .... something to do with molecules of air on a small propeller at high rpm .... compared to larger blades at lower rpm. (small works better)

The real drawback is battery weight of course.

Using Old school lead-acid batteries you needed 500 lbs of battery to equal the energy of one gallon of gasoline
Modern laptop type batteries are better , maybe 300 pounds or so.
But even more problematic is the machine ends up carrying a lot of dead weight (dead batteries) as the trip progresses.
Whereas gasoline is consumed during the trip and the machine progressively becomes lighter.

Take Tesla for example ... they claim up to 300 mile range under moderate driving , but by the end they are still carrying thousands of pounds of dead weight of now useless battery ... which requires many hours to recharge ..... whereas a normal car you just add a couple of gallons of compact light weight gasoline and come home.

Gasoline is a very low cost until our governments add all the taxes . It is a very potent form of energy , pretty hard to beat , there is lots of it and it is safely distributed everywhere .

I have to ask this:
What is the use of going with a traditional anti-torque rotor placement if you're rewriting the helicopter playbook?
What if, instead of an array of small rotors on the tail as he has now, he had two smaller sets of rotors either side of the aircraft?
He obviously isn't using a large airfoil at the back to induce force when at speed, and isn't using a linkage to the MR/gearbox.

So what benefits to the keeping TR in the traditional location instead of a more compact system, which would even have an added benefit of providing forward/backward thrust and thus reduce the demand on the battery by the MR?

Maybe with a scale model, but in real life, a large rotor moving lots of air to a smaller speed is far more efficient than a teensy rotor moving small amounts of air to a much higher speed. Losses around the tips compared to the size of the lifting surface. A glider with a high aspect ratio is more efficient than a small wingspan.

I think small single or multiple rotors on long tail boom more efficient due to leverage
rather than bigger propellers close to cockpit.
R