Your run of the mill quadcopter is an ideal example of just throwing together motors + batteries + tech and getting a flying machine out of it. It feels inelegant to me because if any of those systems fails, the entire vehicle drops like the non-fliyng-thing that it is. Even helicopters auto-gyro for a period of time after engine failure and can firefly "fly" to a quick landing.
If there is a continuum running from "flying machine" (like a glider) to "rock", the "wing suit" seems laughably close to the rock end of the spectrum. Throwing electric motors at it.... </rant>
To expose my hypocrisy, I'm a huge fan of the lifting body program out of Dryden Flight Research Center (now Armstrong Flight Research Center) of the 1960's.
There's the old saw that airplanes fly using lift, but helicopters fly by beating the air into submission.
You are not wrong. That is a valid lament.
But, this is the definition (or at least a very common result) of innovation/progress.
Tech/automation advances to the point that non-artists, non-experts can do a thing competently or even expertly. Photography use to require expensive equipment, skill, and knowledge. Modern advances in digital sensors/lenses/flashes/post-processing makes everyone able to take professional quality photos. There is, of course still masters and talented artists that surpass. But the floor for everyone has been brought up to expert level at least.
Same for film/video, driving, complex maths, and many more.
For newspapers, maybe, but the tiny optics on phones rule out a lot of photographic techniques, to say nothing of sensor quality when trying to pull 20+ MP out of a sensor the size of a tab of acid
My iPhone 11 Pro still takes crap pictures compared to my FX (or even DX) camera body, and that's with all of Apple's idiot-proofing AI bullshit
The PC for everyday regular usage though is indeed dying. My girlfriend has an iPad Air with the keyboard case from Apple and it’s her primary computing device!
J.S. Haldane in “on being the right size”:
“You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force.
An insect, therefore, is not afraid of gravity; it can fall without danger, and can cling to the ceiling with remarkably little trouble.”
(These wing suits are man-sized, so they would break their wearer on impact)
I had thought that cats could fall from any height safely, but that's not quite true: observational studies suggest [0] they have a 50% or 90% survival rate from terminal-velocity height onto hard surfaces, but not without injury.
Still, I'd expect a rat could also "walk away". It's quite a lot smaller than a cat, though it may lack other evolutionary adaptations for falling. And a rat is a mouse, taxonomically: we just informally call the bigger species of mice rats.
[0] http://www.todayifoundout.com/index.php/2010/11/domestic-cat...
The only downside I understand is that R/C helicopters are very difficult to fly, but that should be straightforward to overcome by putting a basic computer + sensors between the controller and the servos - the user could control the helicopter as if it were a quadcopter, and the electronics transforms those inputs with its sensors/gyros to control the helicopter appropriately.
This would seem to save costs due to fewer parts, lower weight, better battery efficiency, etc, but no-one seems to do it. I must be missing something?
Then they also turn out to be a readily accessible tinkering hobby very suited to flying around in areas people have nearby. The whole FPV and racing scenes bought in a demographic shift compared with helicopters and fixed wing. Quads are also fantastically agile so quite a different experience to anything else.
https://abcnews.go.com/US/minute-mechanical-error-led-teens-...
Proper helicopters also require a complicated control linkage on the main rotor and a separate tail rotor. Quad copters (and other multi-blade devices) only need to modulate power to the rotors for control.
I would never ride a quad copter, but they’re better for unmanned use.
But cheaper and fewer parts I'm not so sure, part of the reason drones are so popular is the low parts count and part price.
Most low price hobby copters use 3 motors, driving two opposing rotor blades for stability and a tail blade for steering. There are also several gears and bearings to support their functions. Far easier to strap 4 motors with props to a cross and drive them using a solid state SBC integrated with RF,6 axis gyro and 4 power transistors.
Many of these new hobby drones use all the same parts across several different manufacturers so there is an economy of scale to considet too.
Multiple motors is good as well for any motor failures, as quads (if they're well designed) can fly after even multiple motor failures.
A quadcopter depends on the motors for any control. While it is possible to regain control after a single motor failure on a quadcopter, it's extremely difficult and not something a human pilot could do, so you'd be relying on software. Also, if you don't detect the failure instantly, the craft will flip over before the software can react because of the inherent instability.
Any solution where you have some kind of passive lift and inherent stability (eg. parachute, wing, etc.) is always going to be much safer.
ox
xo
EDIT: I managed to find it, with even number of motors you can prevent unwanted yawing, by letting half spin clockwise and other half spin counterclockwise.
I’m not an expert but IIRC with three rotors you need to be able to control a bit of roll of just one of them to have stable flight control.
For unmanned flight i do agree on multicopters being the best option. See this[1] video for an example of a multicopter flying with disabled props.
However, as you see this flightmode isn't appropriate for human beings, humans should keep flying helis for now. The swash plate design even though more complex than a prop mounted on a shaft is still a rather simple design, litterally a bearing mounted on a 2 axis system and rods attached to rotate the blades. Multicopters with swash plates are interesting too as they can be simplified not to tilt the plate but only offset it up and down to alter pitch the same way all around the rotation. If. This exerts less force on the bearing, but considering there's still 4 of them rather than one might increse failure rate. With swash plates on multicopters we could have two motors driving one system that drives the props, and do many amazing things with computer aided controls in case of failure.
Idk why i keep on going, TL;DR: Being able to control pitch is key, multirotor or not.
I'm not really with Elon Musk on alot of things, but personal human flight is one thing where i agree with him, It's not going to happen.
However, a drone designed to carry pax can be designed with redundancy - the Volocopter, for example, has 18 rotors and engines, and can withstand at least 3 failing.
That can't be reasonably compensated by unless you use a processor which requires way more energy then the rotors ever will.
In practice it seems more complex than that — but I have experienced a softer version of that idea in practice with my own work. Performance does matter, but it isn’t the only factor.
Your point on inefficient code stands, but there is far more at play than mere "programmers aren't skilled enough" and "imagine the possibilities!"
I'll wager a true Mel would not be an easy thing to reoccur nowadays.
That's why if you look at professional drones you generally only see quadcopters when being able to hover and/or execute very precise motions is required, for the rest wings are still generally superior.
Has anybody else shown off similar craft? Uber Air's eVTOL looks about 50% CGI/50% hype, but maybe I've missed something.
There's two critical ingredients: Transitioning out of powered lift immediately after takeoff, and having a battery mass fraction that's as high as possible. Obviously, VTOL & payload limits the latter.
Multicopter designs won't work; their power requirements are too high.
Why did it take until now to get to lithium batteries? Why way NiCad the thing before? Will lithium continue to dominate, or are there other competitive solutions just one breakthrough away? What about hydrogen cells?
Hydrogen is not a solid or a liquid at room temperature and is also too volumetrically in-dense.
A bucket of gasoline contains more hydrogen atoms than a bucket of liquid hydrogen, it contains more chemical energy, and you can actually keep it in a bucket at room temperature without anything terrible happening.
Sure, liquid hydrogen has a lot of energy by weight, but energy storage needs to be good by weight and by volume, and hydrogen is terrible by volume.
There are cases for using hydrogen as your energy storage, but if your thing is smaller than a truck, it's probably not one of them. There's just so much wishful thinking around.
Pretty much everything else about it is bad. Shame.
So hydrogen electrolysis would be the root of renewable chemistry just like fossil hydrocarbon is the root of almost all current chemistry (where even processes that use hydrogen are sourcing that from fossil hydrocarbons). You can have a "hydrogen based economy" even without any meaningful amount of H2 ever stored or leaving the power-to-x plant.
Usage site H2 applications are a dead-end, that's something I would have signed ever since the "hydrogen economy" proposed by George W. Bush (funny how benign hindsight looks at him post-Trump). Admittedly, back then I was also completely unaware that "hydrogen based economy" wouldn't necessarily mean "H2 to the home", I was just shooting down that idea with basically the same inevitability arguments as yours.
Again, speaking from my lived experience, NiCd pushed to the limit resulted in many gnarly fires in high performance RC use, NiMh was never a contender given low output (again low discharge rates). LiPo is king here, both in terms of output and weight/power, but overcharging or excessive discharging results in thermal runaway. Lithium ion is far safer, but less effective.
So I think yet another benefit of lithium is also that it's relatively easier to deal with over its whole life cycle. Elemental lithium is of course quite reactive, don't want to be directly exposed to it, but it doesn't stay that way in nature. That it's extremely abundant and distributed doesn't hurt either. While for economic reasons it makes sense to get it initial from naturally highly concentrated sources, and to recycle lithium packs, it'd be perfectly viable to pull it right out of the ocean with solar power if there was ever a need.
A NiCd cell has 1.2V per cell, a lithium cell has 3.2-3.7V per cell, so they need to have three times the electron density just to break even. They are about 1.5-2.0x higher IIRC and aren't getting better, while we are still improving lithium slowly.
They put out 1.5v just like regular Ds but the end screws off slightly to reveal a micro usb to charge them! I wish I had these for my stuff when I was a kid.
I use them to power my automatic cat feeder. It’s great.
I really could not believe it when I charged them for the first time. Here is a pic https://i.imgur.com/2LoyZlR.jpg
I’ve only done it once in six months for the cat feeder and it hadn’t run out.
No fires yet. Presumably the danger would be in the wiring and power electronics. I’d guess the battery is off the shelf, though I haven’t torn one down—they aren’t exactly cheap.
My favorite part is the action on opening the end. It is slightly spring loaded, but also limited, it won’t come apart. Someone clever designed it.
They have other standard sizes as well, but I haven’t tried them.
But people tend to greatly overestimate how much lithium batteries improve: we remember a class of battery powered devices that ran on NiMH, then at some point LiIon became cheap enough for that use case so that the next generation that we got was so much better. We then extrapolated a fantasy battery improvement speed from that one-time jump and this mistake is rarely corrected. Instead it was supported by the next device class that got absorbed by the ever shrinking lithium price threshold. This process is now about finished, very few NiMH applications left to get "lithiumized". But the fantasy also supported, one a lower intensity but enough to impede corrections, by how the actual actual progress within lithium batteries (not quite as big as we wish, outside of price at least) gets complemented by devices becoming more efficient (think LED flashlights) and devices dedicating an increasing fraction of their mass/volume to the battery (smartphones, laptops, also cars if you compare to pre-Tesla electrics)
How do you know we aren't near the end of what is possible with batteries already? I assume that people in the steam and internal combustion era thought things would just keep improving forever as well.
Maybe at the beginning of steam, but as early as 1824 Carnot had put a theoretical limit on it.
This only goes to 2005 and is plateauing at 200. I checked and a Tesla is 250-260 or so. Seems rapid growth is definitely over and we are at the asymptote.
To a reasonable approximation, the day we run out of lithium is the day we’ve mined the entire planetary surface.
Certain kinds of lithium batteries can be limited by the availability of other elements used in them, which are less abundant than Li, e.g. cobalt.
There are efforts to reduce or eliminate the use of such elements.
So there are lots of alternative batter chemistries that all have lithium as the common element.
Rings, cylinders, valve seats, there are plenty of ICE components that wear out or coke up long before anything on a brushless electric motor will.
It makes more sense to compare batteries to tires and brakes; they're wear items. And their cost will keep dropping as their scale of manufacture increases exponentially until the economics start resembling tires too.
The kinds of electric motors that go for decades with just a couple pumps of grease are reserved for industrial applications because their economics doesn't make sense for consumers most of the time.
I like my cordless drills and grinder but I'm not delusional enough to compare them to industrial motors that are twice (or more, they tend to have massive cases) as heavy for the power output and live for decades. I have a 15hp motor kicking around that dwarfs a Tesla motor in every way except output. That kind of stuff is monumentally inefficient for any non-stationary use.
3yr and you're done sounds about right for consumer battery degradation in hard use. How long a battery lasts is basically a reflection of how nice you are to it in terms of charge and discharge cycles and how much reserve capacity you want to tote around.
We've got electric motors pretty much down and can build them for just about any use case but for a given longevity vs power output batteries are still pretty bulky for the output you get.
This is a mighty big "if."
Re: electronics, the electronics are by far the highest-failure item in ICE cars and in the mechanical appliances I own. Indeed, every failure I've had in cars I own and those of my family owns has in the past ~15 years been an electronic problem. That's only usually been the case with appliances and tools.
There’s a ~90% chance you’re using a device powered by a lithium chemistry battery to read this right now (laptop or tablet or phone). The smartphone alone (enabled by lithium based batteries) has transformed the world. Lithium-based batteries have impacted public health & healthcare (e-cigs vs conventional, medical devices like insulin pump, etc), micromobility (e-scooters, e-bikes, electric wheelchairs, etc), countless accessories (smart watches, smart speakers, wireless earbuds), grid storage, electric cars, electric buses, electric trucks, electric ferries, electric rocket pumps (RocketLab), satellites, submarines, civil drones (like Zipline), and a whole bunch of things that have not yet been invented and perhaps require improved chemistry like lithium metal anode or lithium sulfur or eventually lithium-air (enabling long-haul electric flight, even supersonic flight).
For things like this article described, it will enable more expansion of form factors and reduce costs. Jet suits have been done before but equivalently-specked electric motors are much cheaper than the small, micro turbines used for projects like this. And micro turbines have such atrocious efficiency (about 4.4% for hobby turbine engines... meaning their fuel supply only has a useful specific energy of about 1.9MJ/kg or 525Wh/kg, compared to 0.5 MJ/kg for high-C-rate LiPo, 1MJ/kg for really good production Li-ion and 2MJ/kg for low C rate lithium metal anode cells and lithium sulfur) that after another few decades of battery chemistry improvement, electric microturbines not only will have punchier power but also longer duration.
There’s a ton of undeveloped opportunities out there that will be enabled by the efficiency, convenience, low-cost, high reliability, and oxygen-independence of lithium chemistry batteries.