Comment by manfredo | Hacker News Reader

Comment by manfredo | Hacker News Reader

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Aren't flying cars called, "helicopters"?

Perhaps a bit too snide, but helicopters can take off and land vertically and can carry roughly as many people as most passenger vehicles. And they're mature technology that has been around for over half a century at this point. The problem of moving people through the air without a runway for takeoff and landing has been solved for 60+ years.

What advantage does this flying car have over a helicopter? It's a quad rotor craft so presumably is mechanically simpler (no swashplate) but at the expense of lower speed and reduced ability to operate in the wind. Also it means a crash if any of the four rotors fail (no autorotation). It can also drive in the road like a car. But on the other hand it looks like it seats just one person, and in an open top vehicle so it'll be uncomfortable in the rain.

Helicopters are already supplemented by cars in most use cases. I don't really see the advantage of a flying car over flying a helicopter to the nearest heliport and driving in a car the rest of the way. The only real advantage is the fact that there is no vehicle change. But that comes at the expense of using a vehicle that makes major sacrifices to both fly and drive on roads.

This is true, but also not true. Helicopters are stuck as a concept: large main rotor and tailrotor and also expensive parts and traditional aerospace practices. There are other physical paths, e.g. Osprey, Cheyenne.

But the big thing now is batteries and electronics and brushless motors. It allows flight at a whole new level of cost/safety.

Compare with toy-drones - your point here to me reads like ”there’s nothing new with these quad-rotor drones, we’ve had gas rc helicopters since forever”. And that is similarly wrong as saying these new vtol concepts are just helicopters. Fundamental tech enables the concept of flight to be reinvented using first principles. We know a bit of where this is going in small quads. For manned flight it is still unknown.

Helicopters are "stuck" because they've largely settled into an optimal configuration over the 70 years if experience designing helicopters. Some of the first helicopters had multiple rotors [1], but those were abandoned for good reasons They have a large main rotor because larger rotors provider greater efficiency. The single large rotor also provides the ability to perform autorotation in the event of power failure. Batteries are also bad choices for aircraft since they have very low energy density by unit of mass [2] combined with the fact they don't get lighter as energy is expended like thermochemical fuel.

These are the main reasons why quadro copters largely remain in the realm of drones and toys. These are the use cases where mechanical simplicity of four fixed pitch electric motors shine, and the shortcomings of reduced safety and lifting power aren't big issues (cameras weigh less than people and their families don't sue when they get smashed in a crash). You point out helicopters aerospace practices as a drawback, but in reality those practices emerged to deal with the responsibility and demands of human air transport. What is it going to cost to insure one if these flying cars? How many people's life insurance policies is going to cover rides in these things?

Definitely quadrocopters have made their mark in consumer electronics and even some commercial applications. But I am very dubious that people will be flying in electric multirotor craft.

1. https://en.m.wikipedia.org/wiki/Focke-Wulf_Fw_61

2. https://upload.wikimedia.org/wikipedia/commons/thumb/c/c6/En...

> The single large rotor also provides the ability to perform autorotation in the event of power failure.

That's a nice fantasy but when the SHTF nobody ever seems to be able to pull off an autorotation landing without fatalities. You need enough forward speed and control authority to make it work. An incident when you're at or near hover is unrecoverable.

An incident at or near hover is close to the ground, and so has much better chances of survival.

The issue with multiple rotors is that if one rotor fails the craft immediately pitches over and crashes. The Chinook solves this because the two rotors have a linked shaft. Definitely a quadrocopter becomes unstable with only 3/4 rotors. Maybe the octocopter posted elsewhere in this thread can sustain one failure and still land.

The japanese one has dual props in each position, so it can loose one propeller/motor and still fly (unless they are idiots).

The military might be willing to risk flying people in electric multirotor craft for a few specialized missions such as casualty evacuation.

The military and other rescue service have been evacuating casualties since the 1950s on helicopters. What advantage does this provide over a helicopter? These electric craft have tiny lifting capacity, only 1 or 2 people, as well as much shorter ranges.

Even before helicopters we had Santos Dumont flying his dirigibles down Paris streets and stopping for coffee. :)

Like dual purpose amphibious vehicles and seaplanes , it's a case of possibly useful for very small niches, and maybe electric power, VTOL and not needing the space a single rotor aircraft takes up creates a niche for this vs other similar concepts. But ultimately the economics of long haul flight, accident rates of GA and regulator intervention have all moved aviation further from the 'flying car' model than powered flight demos from nearly 120 years ago, and not through lack of innovation.

Funny enough, helicopter commuter services used to exist, primarily because they allowed one to avoid surface congestion.

Of course, this is only true as long as the skies remain uncongested from other helicopters. And these services died mostly because fuel costs became too large, and operating helicopters on sky-high helicopters in dense urban environments was very dangerous.

didn't think about that, great point!

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