Steam-powered flying machines are a great idea. If we could harness all the steam coming out of annoyed passenger’s ears we’d save a lot on fuel.
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Oh, … you said “eh-steemed”.
Neeeehver miiiind!! 
Maybe a quadcopter could be made with minimal batteries and an engine driven generator, kinda like a locomotive. That would help solve the range problem.
Various hybrid powertrain designs are being looked at. Which are separate from the decision of purely rotor lift or rotor plus wingborne or pure rotor transitioning to pure wingborne.
The weight tradeoffs on flying machines are much more stark and bite much more deeply than on ground vehicles. So the weight of a hybrid, plus the energy losses in power conversion argue strongly against them. Many folks think a hybrid powertrain is the way to go right now, as a sort of halfway house until better future batteries with higher energy density per weight and per volume become available.
OTOH, most of the mechanical complexity (=unreliability and maintenance costs) and vibration and noise come from an engine, be it ICE, diesel, or turbine. Fuel cells would be better, but at current tech they’re as bad or worse than current tech batteries on the density metrics. Of course hope also springs eternal on newer and better fuel cells coming soon too.
When settling on a hybrid powertrain the fear of course is doing all the work to make it work, then being bypassed when battery tech moves beyond you while you’re chasing the gremlins in your overcomplicated and now unnecessary systems. The aviation world still remembers perfecting turbprops in the 1950s, only to have turbojets roar past them only a couple years later. Lotta companies were fatally wounded by their expensive forays up that path leading to valid tech but also to an economic dead end.
so…was Moller a visionary, or a crackpot?
Both.
The “visionary” part was that he had a novel idea and took it a long way past the “wild eyed equations on a blackboard” stage. It didn’t really “work” as an economic product even if it mostly (partly) “worked” as a bit of machinery. But a bunch of that failure can be attributed to the then-poor state of the art in many aspects of aeronautics. Others are getting clos(er) to success today using the same underlying vision Moller had way back when.
The “crackpot” part was in him keeping trying to bore the same hole in the same way while still hitting the same dead-ends. Over and over for decades.
Sometimes persistence pays off. Other times banging your head on a rock only causes eventual Post-Concussive Syndrome. Wisdom is in recognizing early enough which trajectory you’re on.
There seems to be much less “exotic” tech in the battery+motor field than with ICE. You can pay 100x as much for an ICE to get 2x the performance, and people do that. But you can’t get 2x the battery life over mainstream battery technology no matter how much you pay.
The difference is similar to how the absolute state of the art in semiconductor manufacturing is available in cheap, consumer-grade phones. The only thing that makes the tech affordable is scale. It doesn’t depend on some scarce “unobtanium”; it’s just that you can afford development if you can sell 100M at $1000 a pop, and you can’t if you sell 1000 at $1M a pop.
With regards to motors specifically, there’s also a good enough level. The motors need to provide adequate lift and weigh a small fraction of the total mass. That’s already the case with mainstream electric motors. Doubling the performance wouldn’t change much.
Batteries are a different story, and the practicality of a UAM is almost entirely dependent on the energy density of the battery. Doubling the energy density would be an enormous win. But again, that exotic tech doesn’t exist. The batteries in cheap toy drones is pretty much the best you can get.
I agree that certification and maintenance could get expensive. In principle, if UAMs prove to be extremely reliable, then perhaps these costs could be reduced. But it’ll take an attitude shift first.
Agree this is the nub. Hope springs eternal that that doubling is in the offing. And at least at first those newly doubled batteries will be extra expensive. Which was the central idea I was working towards.
Agree that massive scale is a great cost leveler. A lot of the hope of UAM is to achieve automotive scale with flying machine tech for the first time in history. And just as cars took over the world as they became everyman cheap in everyman volume, so might UAMs. Might.
Yep. I am by no means certain how it’ll play out (but cautiously optimistic, as always).
It’s interesting how tech development parallels biology in that features that were selected for in one case end up playing a role in something entirely different. Consumer drones, for example, were enabled by smart phones. The MEMS accelerometers/gyros in particular could not have been so cheap otherwise.
So it may be that UAMs can ride on the cheap components enabled by electric cars, and get the price just low enough on the non-shared components to ride the cost curve into even greater scale. They don’t have to be “Toyota priced” right away, but it needs to be such that cutting the price in half more than doubles the market, so that the additional revenue can be put toward further development and scaling. If not, it’ll just be stuck in its niche forever. It happens. But it would be neat if it didn’t.
Yeah. I suspect they’ll get stuck as taxicabs. Too expensive for a homeowner, even a comfy-class one, to own for an hour’s use per day. But common enough that when heavily utilized a la Uber cars, the fares can be within the reach of a family of 4 riding downtown to see a show in the evening or a museum or whatever during the day.
The well-heeled can use them as daily commuters, the rest can use them as rides to the airport or whatever.
That’ll still give big scale, just not huge scale.
I think you are all wrong about this. There will be no flying cars in the sense that Alef is talking about: being on the road, seeing a traffic jam and just hopping over it. That’s their stated use case. And it’s a fantasy. Ad-hoc flying at low level over people will not be a thing. But then, everything else about the Alef plane is also a fantasy.
Flying cars do not solve congestion, for a simple reason: separation requirements. These are not just something you can wave away, because the airmass around cities is turbulent and flows in many directions around buildings, etc. Right now we require 1,000 ft vertically and half a mile horizontally for light aircraft. Perhaps for slower speed air taxis we could cut that a bit, but not too much. At normal separation requirements that’s about 20 aircraft per cubic mile. Maybe we can get that to 100 per cubic mile with slower craft, but that’s not doing a damned thing for congestion.
This isn’t about pilot ability, either. Autopilot or AIs flying the machine do not help. If you hit a downdraft you are going down until you can correct, and sometimes you can’t correct easily. If a crosswind hits you, you could be moved hundreds of feet to the side before you can correct. Even knowing it’s coming doesn’t help, because you can’t correct until you’re in it, or you’ll fly out of your corridor.
Plus the fact that short hops will mean always climbing and descending, crashing theough other people’s altitudes. And being at a relatively low altitude around built-up objects, wind shear will be a regular occurance.
Then you have the problem of local congestion: An office building at quitting time has hundreds of people all wanting to fly out of the same little area at the same time. The downtown area might have 10,000 people all trying to leave at the same time.
Then there’s weather. If you had even 10% of the people in the sky as are on the roads and a thunderstorm hits, it will be raining metal. So people would have their flying machines grounded every time thunderstorms are in the area, which in the middle of the country is just about half the days in summer.
We would have to accept outrageously high accident rates as well, just due to where and how the things fly: Too high to be survivable, too low for ballistic parachutes, no auto-rotation or gliding ability at all, short duration batteries, uncontrolled landing environments and flying pver built-up areas all the time. How many have to crash into buildings or people before they are banned or heavily regulated to the point where they aren’t useful for commuting?
I could go on. FOD and noise problems are really difficult. The aircraft will notj be cheap, because they will not sell to the masses as general transportation.
My guess is that if these things actually show up and are approved, they’ll be regulated much like helicopters, only allowed to take off from approved helipads or the equivalent, and subject to standard air traffic control.
They may have niche uses, such as a regular taxi flight from the airport to a factory outside the city or something, but there won’t be cars flying over our cities in the thousands in my lifetime, and probably not in the lifetime of anyone reading this. Maybe Saidu billionaires will use them instead of helicopters for getting to shore from their megayachts.
Molt Taylor built a certified, road-worthy and air-worthy ‘flying car’ called the Aerocar. It flopped. Only a few were made, because flying cars turn out to be stupid idea. Thry make for terrible cars, and terrible airplanes. Terrible cars because they are too flimsy and loud and vibrate and non-crashworthy because they have to be so light. They make terrible airplanes because even though they are light for a car they are too heavy and have a lot of drag.
Here’s a 1954 Aerocar for sale:
I don’t think anyone here believes the Alef makes the slightest bit of sense. I would just disagree that “flying car” means a flying machine that you can drive on the roads. The Moller Skycar is the quintessential example of a flying car, and even has “car” in the name, but it was always a flying-only vehicle. It’s just an analogy.
It’s safe to say that if UAMs have the same rules applied as general aviation, then UAMs will not exist. But to a first degree of approximation, if general aviation is treated with those rules, then general aviation will not exist. So it goes without saying that the rules have to be dramatically different. Which is feasible since the technology of the vehicles is totally different.
Much of the concerns about spacing are solved by having a very high thrust/weight ratio and fast control systems. Even tiny drones are extremely stable in gusty conditions.
Tiny drones have massive power to weight ratios, and low inertia. They fly at a very different Reynold’s number, and the air looks more viscous to them. Flying cars are not the same. We can probably reduce separation somewhat from general aviation requirements, but not that much. When you are flying in the air, a few hundred feet is nothing.
Higher relative inertia should help you, though. It means you are less affected by a gust in the first place.
Electric motors and batteries have pretty much constant power density. With 1000x the mass, you can have 1000x the power. So the power to weight ratio shouldn’t change.
A few hundred feet is nothing today because humans are so bad at flying, and because the machines have so little power. But those factors are set to change.
For the last century “flying car” meant one thing and one thing only: a vehicle that could drive and fly and could easily be switched from one mode to another.
Other firms have been working on electric aircraft for years. They get writeups in technical magazines and sites but make no dents in the public consciousness. Alef, this sad, ridiculous waste of time, is talked about everywhere for the one and only reason that it has the magic words “flying car.”
What the technical community says and thinks is irrelevant to the virality of a flying car. The public does not want an analogy, or a helicopter, or a VTOL, or a watered-down buffoon’s version of a dream. They want a flying car and they will not settle for anything less.
As noted, the public has flying cars in the literal sense, and they’ve been rejected for all the obvious reasons.
Every innovator has given the public what they wanted, not what they asked for. Flying cars are the same. What the public wants is a personal transport device that will take them from one place to another without having to deal with roads and traffic and the other mess. What they ask for, or what they imagine the solution to be, is totally irrelevant.
I expect that if these UAMs actually take hold (a big if, to be sure), all the usual people will say that we still don’t have flying cars. They will be rightly ignored by all the people zipping around in their magical flying personal transport vehicles.
And for the record:
“Flying car” right on the front page. Not roadable. And remarkably close to the modern UAM concept.
For the record, I mentioned those in post #49 and linked to a site that has an article on Hiller, including both those photographs and many more.
It’s a pretty good article, although I’m biased since I wrote it. I’ve been studying the history of flying cars for a long time. They make a good focal point for examining the promises of the technological future.
Why, then, say otherwise? It’s clear that “flying car” did not mean “one thing and one thing only: a vehicle that could drive and fly.”
I consider Popular Mechanics an absolute authority in what counts as a flying car. And while they have featured various vehicles with some kind of folding or bolt-on wing system, they have featured others as well. One example that contrasts a “new flying car” (by Moller, again) against the Hiller concept, which is a bit more like a saucer:
Or here, where they explicitly call the non-roadable Moller Skycar a “flying car”:
Finally, we have this example, which is apparently semi-roadable, but which more importantly states the exact motivation I stated earlier:
The “flying car” is the dream of people stuck in traffic. It really has little to do with being able to drive them on the roads.
I don’t think anyone who ever longed for a flying car gave a thought to a vehicle that could also be driven on the road. While the hell would you be on the ground? Flying cars are VTOL only. Has the old Supercar puppet show been mentioned? That was a flying car.
Grounded by a thunder storm or other bad weather.