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.
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  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.
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.
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.
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 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.
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.
Very cool; it appears to be an assist, however, without the power to actually do a takeoff.
Another thing to consider is that saying it has 15kW motors and 5 minutes of thrust does not necessarily mean 5 minutes at 15Kw. That would work out to 1.2kWH weighing what I guess to be about 40 pounds in batteries alone.
I'm really impressed by wingsuits, and strapping a motor onto one just makes it that much cooler.
Absolutely not. Sony VTC4s are early 2010s cells that do 30 amps continuous with 2000 mAh capacity. 172 cells weigh in at 17 lbs, 1.2 kWh, and a whopping 16.5 kW continuous rated output.
For lower power applications, higher-capacity cells like the NCR18650G weigh below 10 lbs per kWh.
Normal wingsuits can easily reach ground speeds up to 250kmh/155mph.
Reference: plenty of experience pushing 8KW+ through 2KG RC gliders (F5B) and far slower EDF models.
They chose not to do this because the more onerous form factor results in amputation of the pilot's viscera and legs.
Granted, that could be an issue, but once the government contracts for production of a few thousand units such minor flaws can be addressed with a field upgrade package, barely tripling the unit cost.
HOWEVER, efficiency is maximized when outlet velocity matches airspeed (or you have wasted momentum that will dissipate into heat, when your outlet stream mingles with the rest of the atmosphere). For your slow gliders, a small ducted fan with a high outlet velocity will indeed be quite inefficient. But this guy, traveling at hundreds of mph, needs a propulsion unit with a similarly high outlet velocity. A big, slow thing isn't going to cut it for that. A big, fast thing would, but would also blow their power budget. Within their design constraints, this is pretty close to the optimal solution.
There's also the small matter of free props being horrifically dangerous :)
 They've helpfully given us enough information to work out some basic aerodynamics of their fans. At 7.5 Kw each, assuming 90% efficiency each of the motors and ESCs, and eyeballing the duct and hub diameters as 18cm and 8cm each respectively (could be off, here), we should expect an outlet velocity of about 230 mph. The guy reached an airspeed of nearly 190mph, or over 80% of the outlet velocity, so they aren't doing badly at all considering the drag.
If you're specifically looking at autonomous flight of drones, then the Udacity Flying Car nano degree is not bad (it contains several mistakes, but takes you through quite some material with neat exercises). It presupposes a bit more maths and programming. I was free (for a month) during the early stages of the pandemic, now I think it's back to normal prices.
I'm also open to the idea that a HN'er teaches us.
Yes, I know what I'm asking.
You don't have to do it ;-)
It would just be really nice :)
If electric is assist, what would be the main power source?
> “I found the idea of being able to jump from my local mountain wearing the wingsuit and land in my garden fascinating.”
EX: F-15 landed safely with just one wing. A little cough propaganda, but still interesting: https://www.youtube.com/watch?v=M359poNjvVA.
The article itself mentions typical horizontal speeds of around 62 mph.
The Wikipedia article on wingsuit flying says:
> A typical skydiver's terminal velocity in belly to earth orientation ranges from 180 to 225 km/h (110 to 140 mph). A wingsuit can reduce these speeds dramatically. A vertical instantaneous velocity of 40 km/h (25 mph) has been recorded. However the speed at which the body advances forward through the air is still much higher (up to 100 km/h [62 mph]).
Even mentions another jetpowered attempt with hydrogen peroxide rockets reaching a horizontal speed of 160 mph, back in 2007.
In practice that is difficult to do on most BASE jumps as you need to sustain a steep angle for 10-15 seconds to hit that speed. Density altitude will greatly affect performance as well.
What's cool is being able to sustain 180mph while not losing altitude, which it sounds like BMW+Salzmann have accomplished. From the article:
"While Salzmann’s first flight was a resounding success, it appears he’s not resting on his laurels. According to BMW, the daredevil wants to fly between the skyscrapers of South Korea next."
I've dreamed of being able to zigzag through downtown skyscrapers for more than 10-15 seconds. The Jetman project is astounding. From a friend who is working on a copycat, the costs are close to 100k to replicate. Eager to see experimentation+progress on any projects with the promise of making hybrid human+wing flight more accessible (cheaper).
To maintain level flight they need to generate a lot more lift, while carrying the extra weight of an engine. By comparison a 747 has a glide ratio of 15:1 and depending on specific model and how much weight it has onboard it will stall in level flight around 180MPH. While many aircraft can fly at much lower speeds, a wingsuit is a terrible aircraft.
Also, when I was in 5th or 6th grade (over 30 years ago) I was obsessed with the F-15. Talk about thrust:weight ratio. The idea that you could take off, point the nose to vertical, and accelerate past the speed of sound, then level off and get to mach 2.4 or so... simply amazing machines.
So someone starting with a deep dive in a wingsuit can level out and get very fast horizontal movement. There are a few videos of people doing this and reaching almost level flight though their slowing down. It’s maintaining speed that requires thrust, but speed is enough for level flight.
Also, while you could effectively balance on a jet engine to hover, that amount of thrust would also allow you to do not just level horizontal flight but rapidly gain altitude, making it kind of a meaningless from a minimum speed to requirements for minimum thrust perspective.
My wife and I were pretty active jumping in the era of wingsuit videos on YouTube. In her first year we had one good friend die and 9 people we'd met or hung out with a short time. It is basically comparable in danger to spaceflight.
Unfortunately I share your same statistics: I was very active in the early 2010:s and in that period I lost about 10 friends/acquaintances. Since then even more people I've hung out with are gone.
So yeah: wingsuiting is dangerous. But BASE itself can be done "reasonably" safely I think: personally I was always more fond of slider down (low) stuff, like buildings, and in my mind that's a safer sport than wingsuit BASE.
in this vid he's jumping out at 10k ft which makes it closer to skydiving.
Obviously cool if you can do similar things with electric as well.
Me: turns off sound
Don't get me wrong, I love it, but I don't really see what they were seeing when they made this.
With electric, apparently BMW becomes another candidate (who seem to be desperately looking for ways to get their name visible in a context that somehow combines "electric" and "exciting").
The noise is really bad and one of the reasons I'll vote against any local ordinance that would make heli-transit more available.
The Hudson River is less than a mile across at Manhattan. This could be faster than car/train/ferry/bike for some very specific commutes.
"Living in Hoboken, New Jersey, the other side of the Hudson river to Manhattan, Schwitzky kayaks across the water in around 20 minutes."
A PHEV X5 could be the killer product with the X5 already being one of the best selling cars in its segment except it takes 6 hours to charge on a lv2 for the full 30 miles range due to the current limitation. The battery itself seems to be able to handle much higher current when it charges off the engine so it seems like an artificial limitations to prevent the PHEVs from competing with the few BEVs they struggle to move.
Obviously they're powered so they're different, but I remember a lot of wing suit debates where even professionals felt that the envelope between 'safe' and disaster on wing suits was way too small for even professionals to use. A lot of that seem to have to do with the jumper's sense of how stable they are / compared to how stable they actually are and how that could get way off at times and even pro's weren't able to manage them well enough.
It's a BASE rig since it only has one parachute, and the sole canopy is designed to deploy quickly and consistently.
Another clarification - BASE rigs with wingsuits are not inherently dangerous. In fact, BASE/wingsuit gear failure as a cause of death is extremely low. It's correlation vs causation - BASE rigs are used almost always (except for certain stunts like this) used in a BASE environment flying close to land, where the margin of error (time to impact) is extremely low compared to a skydiving environment.
In a skydiving environment, you can do everything wrong, even do nothing and likely live (automatic activation device triggered deployment of your reserve canopy). But with BASE, oftentimes you are flying so close to terrain that you cannot deploy your canopy and live, and your only option is to continue flying your wingsuit to a safe place to deploy - which is a problem if you stall, take a slightly wrong line down the mountain, etc.
Source: I'm a parachute rigger and I wingsuit (in a skydiving environment).
The cheesy music and SFX put me off.
There is just no way that small unit could generate near enough thrust to make a real difference.
I think we need to look deeper into this claim
Fans that small put out enough force to literally push you straight up. Jetcat has an engine 23 cm wide which can pull 110 kg. For the same size an electric fan passes much more air.
The fastest wingsuit flight almost topped 400km/h so maybe the real question is how much extra speed was gained with those little EDFs.
That time in "flight" doesn't seem much different than the time it would take to plummet to your death. The only material difference seems to be the not dying part.
On a side note, I think it's going to be an interesting decade for all sorts of sports. Different variants enabled by technology, and every-improving athletes and engineers are going to be working on very interesting demonstrations I bet.
It's amazing how little morals people have nowadays when I have to defend not wanting people to die.
Slide 6 - the barely visible brown line hugging the x-axis is outdoors.