There's no "bicycle" of jetpacks, you've got three axis of movement and certain death in every direction but up, it's just not a tool that belongs in the every-man's garage.
I think the same can be said for the past's perception of what flying cars would be like. You don't see your average joe flying a helicopter to work, for the very same reasons you'll never see personal flying cars be ubiquitous.
You've got two axis of movement at 60mph. Stray a couple feet left or right and you die in fiery inferno. Stop too fast or too slow, same deal. Maybe appropriate for highly-trained specialists, not for every-man's garage.
My point is not that "cars are death machines no one should own," although there are certainly those who hold that opinion. Rather that inherently dangerous things can be made relatively safe with enough systems around them: roads, signs, traffic laws, licenses, seatbelts, and so on.
To be fair, the eagerness of people to do activities that feel risky but actually aren't makes that prediction harder than it looks at first.
We don't trust people to operate cars on a road without DMV certification, FMVSS regulations, and a substantial amount of liability insurance.
The "average joe" in some regions may not fly regularly, but around here there's many farmers with Cessnas that do routine work.
Currently, if you have a use for it and are somewhat competent, it's practical to fly and not out of reach for the common man.
But in no near future do I see them reducing the restrictions, flight hours, air traffic protocols, etc.
That being said, I don't see much practicality for a jetpack other than sport or rescue.
I can of course picture a world where there are automated skyways, and electric AVs guide themeselves from abode to shopping mall airport, I'm not without imagination. But I'm not hopeful.
Showing that cars are scary doesn't disprove that flying cars are more scary
There is no good "emergency braking" for jetpacks, there is not even "autorotation" as there is for helicopters.
Jetpacks, and the flying car, have more possible ways to move.
The Jetsons used to show the flying car working the way the normal car did - highways in the sky - that's basically the way it would have to work to be made safe, as long as there are any sizable amount of users of the jetpack or flying car.
The jetpack has of course other hazards associated with it such as the engine being really close to the human operating it with significantly less shielding than one has on the car.
on edit: I think there might have been problems with the car in some Jetsons and George had to parachute to safety, arms crossed and a seriously miffed expression on his face.
1. It would have to be significantly faster, able to go longer (makes sense this would be the case because obviously you can fly quicker than you can drive so I assume this benefit will be a gimme, but it has to be significant for people to care. If you can make the flight to grandma's house in 3 hours instead of 8 there would be interest)
2. It would have to not cost very much more to own or to run.
3. It would have to not be any less safe for drivers than it currently is to drive - at the beginning this might be the case because less drivers means more safe maybe.
4. there would probably have to be significant safety features built in to keep flying cars from causing catastrophic damage if they failed - this seems to right there make it impossible because it has to not cost much more than a normal car.
5. There would probably have to increase in automation of cars to be able to detect when something wrong, when someone breaking flight rules etc.
6. no internal combustion engine flying cars, because a falling car with internal combustion engine is also a potential bomb.
so what are the benefits - we've already mentioned 1 but are there others?
Conceivably with a mass movement to flying cars instead of cars the infrastructure of cars would no longer be needed or need to be maintained. A utopian vision would then be that all that land that is currently big packed freeways get converted to parks etc. although a cynical vision would say oh nobody would want to pay for that and they turn into dystopian hellholes and kids go there to get eaten by coyotes.
Possible benefit #3 - to make safe have to have much routes for everything but given that we have all the sky conceivably there could be more routes, including emergency routes that would be left to emergency services or people registered for a possible quick route (quick routes to hospital for birth etc.) All of this of course implies flying cars with effective computer surveillance of drivers.
So I see these benefits to flying car - 1. quicker longer trips enabled. 2. No longer need driving car infrastructure 3. possible solutions to congestion are still available with flying car.
But does that mean it is doable.
I think the needed functionality points basically cancels out it ever working but maybe I am pessimistic, although I do think that now we are actually getting to the point where the necessary prerequisites for flying cars are starting to be built - specifically good electric cars and driving automation and services (but way early for that, flying cars in 100 years at this rate)
Does anyone do a pre-drive walk-around and engine test of their car, or do they just turn it on and go? If you're in a city do you request permission to begin a trip from a DMV controller via local frequencies, or just go wherever? Does every home have a runway or just a driveway?
These aren't insurmountable challenges but there are chasms on the way from possible to safe to convenient.
(Also to your point 6, I'd add to the Kzinti lesson: any energy storage device is a weapon effective in proportion to its stored power—gas tank, flywheel, Li+ battery, dammed hydro, you name it.)
Airplanes you can at least use simulators and flight instructors who can take control when you mess up; jetpacks you lose any opportunity for a co-pilot, so you probably need good flight simulators you can log hundreds of hours in before strapping in.
Humans evolutionarily think about movement with a 2 dimensional mindset because for much of our history we only needed to think about 2d movement. It's why even modern flight is centered around the idea of stacking multiple 2d environments (via elevation / flight levels) and then just ignoring that 3rd dimension for the most part.
This is why something like a car is operationally intuitive -- humans don't need training to quickly pick up the interface for one, even a kid could operate a 2d vehicle. The systems around them mainly manage the risk around _conflict_ introduced by having multiple actors.
This is also where a plane (or submarine, or jetpack) is fundamentally different. The systems around those need to manage not only conflict but also our sensory deficiencies. It's very easy to get disoriented in 3d movement (it's very easy to lose the ability to tell up from down) and there have been plenty of plane crashes due to this. That's why pilots need to infer their orientation from instruments rather than just their senses. That's also why flying cars and jetpacks are not widely available -- the amount of training just to operate such devices _alone_ is already very high, let alone having to manage conflict in addition to that.
Citation required? If you hang out with a child you quickly discover that their world is quite three dimensional. Heck, climbing is a fast growing sport. Again, three dimensional. We're made to run, jump, and climb. Three dimensional.
"When there is no visual input as is common in many flight situations, we rely more heavily on our vestibular sense for this information. However, in flight and in space, our vestibular system, _which is designed to work on the ground in a 1g environment_, often provides us with erroneous or disorienting information."
We have a system to somewhat understand and orient ourselves in 3d obviously, but it has quirks because evolution tuned it to work best on the ground + assuming 1G of gravity as "down".
Orienting in 3d is not intuitive for us. We can do it but we need a _lot_ of help to do it safely.
Ummm… no? The surface of a mountain is still two dimensional.
2) Humans are great at throwing and catching objects, even with complex, changing trajectories--bouncing off walls, etc.
3) We have two innate senses that are clearly adapted to 3 dimensions: stereoscopic vision and proprioception.
What makes those behaviors relatively intuitive is constant acceleration. In a sense constant acceleration makes everything 2D. (Or 2.5D?) When humans need to track objects which independently accelerate along 3 axes, then there's a much stronger case for an environment alien to humans. (Counter point: hunting birds, though I believe hunters prefer to take their shot when birds are beginning or ending their flight. But notably the most salient characteristic there is acceleration, not merely relative movement in 3D space.)
Yeah, the more that I think about it, you get much more predictive power by emphasizing acceleration, not spatial dimensionality. And I don't think that's being pedantic; the distinction matters. When you look at studies of how the brain processes motion, constant acceleration (at least along 2 of 3 axes, unless/until hitting another object) is often one of the key assumptions that seems to be built into our cognition.
For example, tracking many objects moving independently in 3D space is pretty darned difficult for humans.[citation needed] But that probably has more to do with relative motion (and thus relative acceleration) than with the number of dimensions as a human can track two such objects surprisingly well, especially if they have a third, fixed reference independent from themselves.
Would be curious to compare & contrast studies of spatial cognition between marine animals and terrestrial animals, though.
If it helps, think of what everybody else is calling "3-D" as "no obvious primary axis."
That's for sharing the space. It's not only a set of stacked 2D environments, those are also divided in road-like spaces, with a limited number of junctions.
We sense "down" based on assuming that 1G of acceleration is the "down" position. This is fine if you're stationary. This is fine if you're moving in 2d. But accelerate in 3d and all of a sudden you can get completely disoriented because the "down" you're latching on to could be any acceleration vector.
We _can_ manage this, but it is an acquired skill and we need instruments to help us. Pilots (and especially fighter pilots or astronauts who truly experience a lot of 3d acceleration) need to train for years to acquire this skill.
Can you imagine training an average person years just to _use_ a jetpack? That's why we have jetpacks and yet most people don't care.
For an astronaut in orbit, going ‘up’ means accelerating. Going ‘down’ means slowing down. Going sideways (in the way we typically think of it) involves changing velocity in least 2 vectors twice, etc.
I may be misremembering, but the idea is there's a special race of humans who have continued to evolve living in low gravity (space) environment, and the terrestrial human (those living on planets) governments would hire them as space mercenaries because they're at a huge advantage when it comes to 3d combat compared to training some terrestrial guy.
There is a trilogy of books written covering Khan's life and it very subtly shows why Khan has this difficulty, but never points at it and shouts.
Teleportation tubes on the other hand...
And just like cars, you wouldn't be flying it randomly, we'd have to build "lanes" at different heights, etc. You don't drive your car randomly through buildings. In fact, connecting to a network and having it fly for you would be the most likely scenario.
Not to say that there wouldn't be "free flight" parks around.
Generally you want to fly at a constant altitude because climbing and descending require energy transfers. Humans have little trouble coping with the concept of 3-dimensional flight, indicated by the enduring popularity of combat flight simulators, but aircraft that aren't built for combat physically struggle (and even in those that are, such flight demands careful energy management).
The humans evolved to brachiate for a lot longer than they've been wandering around savannas.
> even a kid could operate a 2d vehicle.
Trying this was a mistake and nearly got me killed. Twice.
JFK jr
The jargon term for this is spacial disorientation.
That might depend on whether the aquatic ape hypothesis is true ;)
More seriously, in addition to diving and climbing, humans have been using throwing weapons for hundreds of thousands of years -- not the same as navigating one's body through 3 dimensions, but it still requires a 3 dimensional mindset because you need to work out where the trajectories will intersect with something traveling in a different plane of movement. So I'd be curious how much hard evidence there actually is for human deficiencies in 3 dimensional thinking compared to say dolphins or parrots.
Currently designed Jetpacks don't have brakes, or any safety features really, but that's just a lack of development.
You could easily think of hundreds of safety features that would make Jetpacks in a distant future seem pretty safe, from auto pilot/recovery features, automated object detection and avoidance, body suits with built in airbags, better designed packs that give things like 100x better articulation control, built in parachutes, the list could go on forever really.
Meanwhile cars actually have additional dangerous properties: being stuck in very confined tracks where any other user errors affect you, limited visibility, and a massive amount of heavy metal surrounding you.
I don't see why Jetpacks couldn't be as safe as a cars given they had an equal amount of investment into safety as we see modern cars. And to answer the article as to why they aren't popular, it's pretty easy to see that they just kind of suck as they are now, they need improvements in nearly every dimension.
Even with a practical power source, you know have an immense amount of energy stored right next to your body. You need to be able to direct said energy in a safe way. Good luck.
There's only so much airbags can do. Imagine where you would locate those airbags. Cant be pressed against the body either (airbags can cause horrible injuries). Parachutes won't help close to the ground.
First, for usage of cars in society, there’s a nice gradual curve where an early slow unreliable car is still somewhat useful, and a faster car is a bit more useful, etc, and that’s what allowed them to get off the ground (as it were). There’s a vastly higher threshold before jetpacks start being usable and useful.
Second, cars are relatively fail-safe in that if you take your foot off the accelerator the car will coast to a halt. Lots of cars can easily come to a safe stop together -- traffic jams are bad but not immediately life-threatening.
Jetpacks aren’t nearly as failsafe because if you stop flying you need to land (or more likely, crash-land).
Planes have the same two advantages over jetpacks, because even a slow or unreliable plane is useful because it can carry cargo; and most planes can glide a bit which helps reduce the risk of crash landings.
While this is true, the issue is that what is required for "enough" can vary very widely. In particular, what would be "enough" for jetpacks (and flying machines more generally) is a lot more than what experience has shown to be "enough" for cars. Some indications of why that is are the frequency of airplane accidents involving experienced pilots, who have had a lot more training on how to fly a plane than anyone gets on how to drive a car, and also the amount of time and effort and the level of continuing human supervision required to keep commercial air travel as safe as it is, even though that also involves experienced pilots and has the support of many complex systems.
Your engine dies while flying, good luck, pal.
(As other posters have alluded to, parachutes won't save you at low altitudes. In the mean time, it's further weight on your back on a device which is already difficult to control, and not really optimal for releasing next to jets of hot kerosene either)
Speeds up deploy time by making the deploy happen, instead of waiting for gravity/airflow to deploy it.
[1] https://cirrusaircraft.com/wp-content/uploads/2014/12/CAPS_G...
Are there full body airbags? Could that even work?
Let me know if you find out. I have got to get one :-)
I was picturing a massive bubble with me in the middle so I could jump off the roof and bounce away or something...
What do you know that makes you say "that will work"? A planned and controlled landing for a rover (engineered from metal and stuff) on a planet with a gravity 38% that of earth is rather different from this hypothetical emergency system for fragile humans on earth.
For example: Velocity from a 100 metre (300 ft) free fall is v = sqrt(2gh) = 44 m/s = 160 km/h = 100 mph.
Now let's say we might survive 5g to 50g (Astronauts pull 5g routinely, Lady Di in her car crash had about 70g).
So, to brake a fall from 100m somewhat comfortably, you need a 20m cushion. To brake it such that you have a small chance of survival, you need at least a 2m cushion. This scales linearly with height you fall from, until you approach terminal velocity.
Interestingly, terminal velocity is around 200 to 300 km/h (depending on position), or 125 to 185 mph, or 54 to 80 m/s, requiring a 3m to 30m cushion.
A 30m airbag in a jetpack strikes me as unlikely. A 2m airbag in a jetpack that achieves constant deceleration may be feasible, though not soon, and certainly not something I want to experience.
For reference, these Fall-Pac units at 1.2 metres cushion promise fall protection up to 3-5 metres.
https://fall-pac.com/wp-content/uploads/2021/09/fall-pac-fal...
https://en.wikipedia.org/wiki/John_Stapp#Work_on_effects_of_... shows that 50 gees is survivable, at which speed you need 120 ms and 3.6 m to decelerate from 60 m/s. Not pleasant but still safer than a car crash. If the airbags inflate before you hit the ground your terminal velocity is much lower, decreasing roughly in inverse proportion to your hydraulic diameter (√(2mg/ρ/A/Cd)), so a 1.5-meter-radius cocoon of airbags around you will cut your terminal velocity to about 20 m/s, at which point you need 40 ms and 400 mm to stop safely. For this you need something like 4-12 1.5-meter-diameter airbags, 7 m² of surface each; at 20-μm thickness that's 140 cc, and if it's mostly something like gel-spun UHMWPE fiber or polyimide film, it's also about 140 g each, so 0.5-1.7 kg total bag weight --- plus conventionally 2 kg of nitrogen per airbag in the form of 3 kg of sodium azide, which is another excellent reason to perform the inflation well before you hit the ground, so you can use atmospheric air instead.
Suppose you weigh 100 kg. To stop you at a safe 20 gees max when you hit, the bag needs to exert 2000 kg max force or 20 kN, so the pressure in a bag acting over something like 1 m² of your body needs to peak at 20 kPa, about 0.2 atmospheres or 2.8 psi. Approximating hoop stress as ½Pr/t we get a bit under 400 MPa stress in the bag, too much for unaided polyimide but an order of magnitude lower than what UHMWPE fiber can handle. So you can make the bag thinner than that, lowering the weight further, perhaps to 40 g per airbag. There are whiplash shock loading problems conventionally handled in automotive airbags by generous safety factors that can be reduced by origami design and judicious addition of thicker compliant material like nylon.
A 30m airbag would need to be 20x thicker and would have 400x as much area, so it would weigh 8000x as much, 320 kg. This would indeed be unwieldy for a backpack.
You can closely approximate constant deceleration by connecting the airbag under you with other, more voluminous airbags on the other side of you, just as a car tire closely approximates constant pressure when traveling over bumps in the road. But it's not necessary; what's necessary is acceptable peak deceleration and, probably, minimal jerk. It's true that constant deceleration is the best case of minimal distance and time for a given peak deceleration, but even linearly increasing deceleration, like from a Hookean spring, only doubles the time needed to stop when holding the peak deceleration constant, thus multiplying the distance by √2.
So, you see, all the materials and mechanisms necessary are already available, though only in the last few decades. There's no technical risk. It's "just" a question of engineering the thing to not kill people all the time when it fails, based on experience with what the deadly failure modes are. It'll require a lot of work and many deaths, but if people put in the work, it will definitely work.
Let me know if I got any of the calculations wrong!
In a jetpack, yes. Good luck. Drone, good luck too.
Airplane? You glide down.
Helicopter? You autorotate down.
From a safety perspective, you're going to be in a little bit of trouble because this hypothetical industry will have profiteers and customers that simply won't let you regular them much. Cars are a special case because nearly everyone rides in them so safety concerns (thank you Ralph Nader) are politically easy and the capital owning class have a hard time pushing back on stories of dead families in terrible accidents. The capital owning class finds it easy to push back against regulations on motorcycles, thus maximizing their profit, because even people into motorcycles don't want crumple-zones, roll-cages, big flashing lights, bumpers, etc because it hurts the aesthetic and experience they buy motorcycles for. Lets remember it took 60-70 years of motorcycle popularity before helmet laws got popular. That's a very slow regulatory burn.
So the jetpack is a lot more like a motorcycle. Even on well regulated roads full of safety devices they're still death traps because any vehicle without a "cage" is simply dangerous and impossible to be made safe. The NHTSA: For every mile traveled, motorcyclists have a risk of a fatal accident that is 35 times higher than a car driver.
So no, you probably can't car-ize a jetpack because a jetpack isn't a car. Its own unique mode of transportation and one without a cage and something inherently unstable. I imagine your best case scenario is many times the risk of motorcycles. This is why investors, the living arm of capitalism, refuse to mass-fund these deathtraps, but they'll fund any gimmicky crypto or social media thing. I don't think a successful jetpack company wouldn't want to car-ize it anyway. It would take away the appeal and the profit incentive would demand they continue to make them as sexily dangerous and performative as they can get away with to increase that appeal, thus sales.
You also have the larger regulatory and public safety issues drones have. They can't stay aloft without power and come crashing down without wings or autogyration to helps them down. So in populated areas it would be irresponsible to have these flying over the heads of people.
If you have free time, go ahead and visit /r/weirdwings or /r/weirdwheels. There's no shortage of "innovative" death-traps out there that failed to penetrate the market because they're just too dangerous.
Last but not least, single-person transportation tends to be the kiss of death anyway from both a practicality and cost perspective. People are social, have significant others, children, elderly to take care of, etc so the single-person vehicle has to be something you own ON TOP of owning a car or two. It doesn't replace cars, so a prospective buyer is someone who has to make car payments as well as jetpack payments. What percent of Americans can afford this vs people who can afford cars and the occasional airline ticket? Currently, an affordable jetpack is $200,000. If through the miracle of mass production you get that down to 1/2 or 1/3rd that, its still the cost of an expensive luxury car. What market are you appealing to even if you iron out some of the safety issues? Who is this unicorn who can afford this and would want it, especially considering the wealthy tend to be old men unfit to pilot something like this safely and with comfort, the same way the average Corvette driver isn't hot 20 something guys like in the movies, but older men close to retirement.
Google says the average age of a corvette owner is 61. Do you really want 61 year olds flying over your head in Iron Man cosplay that actually flies? Knowing full well if their arm muscles give out then their vector radically changes and more or less turns them into 70+mph human missiles aiming for the ground?
In a country that has traded efficient public transportation like intra-city light rail, trollies, and fast regional links for car culture, well, you're kinda stuck making car payments then. Not enough people can spend $100,000 on a jetpack the same way we all don't have a Cessna waiting for us as the local regional airport. The money ain't here even if you can fix safety and the absurdly low flight time of just a few minutes. The sci-fi fantasy of flying alone above a city is not only technically difficult, ridiculously dangerous, but economically impossible for all put the wealthiest.
At that time, we can revisit jetpacks and use onboard software to completely abstract the horrifically complicated control problem.
1. https://aviation.stackexchange.com/questions/23977/why-arent...
Tiny jet turbines are expensive too.
Personally I think the form that "jet packs" will eventually take is just an electric multicopter that you strap into somehow.
I think a reasonable interpretation of the promise of jetpacks would be more like the "ultralight vehicles" category (as it's called in the United States). These vehicles require no registration or pilot certification. Some are fairly traditional rigid airplane designs (just very small and lightweight), but the category also includes powered paragliders (AKA paramotors) and some of the smaller powered parachutes.
Where I grew up in the US these were fairly common to see in the air, and no one thought it was odd that they didn't require a pilots license. Perhaps for many people in many areas the regulations or different, and it strikes them as absurd to fly aircraft without a license?
It takes 25 hour in a plane to get a recreational license, and 120 supervised hours logged in a car, for people who don't have a relative to do the supervision and need to pay and instructor, the cost comes out more than getting a pilots license.
Once that's done to be allowed on the road alone, they need to get their 2nd provisional license a year later, then full car license a year again after that, with additional tests along the way.
Grab any drone with a 200kg capacity (they do exist), hang a lawn chair under it, and take to the sky. That's probably safer. Jetpacks as a concept might get overtaken by the small helicopters we today call drones.
There are other big, people-carrying drones. eHang was probably the first, in 2016. They've actually sold a few. Price is above US$300K. They routinely fly above cities. Like everybody else, they're battery-limited. Their limit is about 30 minutes.
All those un-shrouded spinning blades at low height are worrisome.
German company Volocopter flew a manned demonstration rig in 2011 (the famous pilates ball [1]), and had the first manned flight of the Volocopter multicopter (certified, 18 rotors) in February 2016, with the CEO himself flying [2].
I don't know when the eHang 184 flew first (a video on youtube says Feb 2018 [3]). Personally, I find the design (with 8 rotors in a quadratic arrangement at knee-height, perfect for decapitating pedestrians) atrocious. (The Volocopter blades are above the cabin, as in a helicopter.)
And where do you get the 30 minutes endurance for the eHang from? When I divide the range by the cruise speed from Wikipedia, I get about 8 minutes endurance.
[1] https://www.youtube.com/watch?v=L75ESD9PBOw
I am admitting this publicly as a reminder to myself and others for the fact that for the public, the process of writing software is modeled by scenes of hackers in Hollywood movies.
There's no reason the same principles can't be applied to jet packs. Add a gyro or two, gps etc to give it the data it needs and the pilot should have a much easier time.
The more difficult to solve problem is with endurance. They are only good for 10s of seconds of powered flight.
You need a pilots license, but you don't need fine motor coordination skills across your entire body PLUS a lot of core strength, in addition to all the problems with moving in 3d.
For this 'jetpack' you are essentially balancing your weight between your back and arms. If you get it wrong for a split second, you'll kiss the ground. It's inherently unstable and tiring since you have jet turbines strapped to your arms.
An aircraft is stable. Let go of the controls and it will keep flying.
The closest aircraft comparison would possibly be with a hang glider, except even there your weight is supported and you are essentially just shifting it around.
Many jetpacks in fiction were envisioned to work more like drones. Tell it where to go and it would do the rest. Iron Man would be similar to this thing, except it is described as a fully mechanized suit (plus artificial intelligence), which magically takes care of some of these problems.
Ultimately, 'jetpacks' will probably never exist. There's an inherent physics limitation when trying to strap a whole human body to the side of something small (and generally depicted as being strapped on your back, Bobba Fett style). The center of mass is off.
Sure, general aviation is safer than driving (e.g. less accidents per vehicle, and less accidents per hour/mile), but general aviation is more dangerous than commercial aviation. I suspect there's something going on with maintenance, training, and available safety features. Seems like lowering the barrier of entry to flying is simply going to increase the accident rate because there's just more less skilled people flying.
Of course most flights crash on takeoff and landing, and conceivably that would be automated, so maybe I'm just being paranoid. Still seems impractical, if for no other reason space restrictions on the ground.
Considering how low the frequency is for your your typical GA pilot, it’s honestly a wonder it works as well as it does.
And that’s just the start. Pilots run out of fuel, fall asleep, they land on the wrong runway/field, and so forth across lots of very small risks that end up killing people.
I am not saying GA should be more regulated, it’s just important to understand the trade offs in terms of freedom vs safety.
What I mean by the ‘cream of the crop’ is you have to be more experienced and pass far greater hurdles (including a far more demanding medical exam) than any GA pilots need to, just to be licensed to try to get hired as a commercial pilot.
It doesn’t mean there aren’t great GA pilots out there - there are! It just means that only the top x percent of GA pilots could pass the requirements to be a commercial pilot.
That's not correct. For a US commercial pilot's licence, the hours requirement is 250. It's 1500 hours for an airline transport pilot's licence.
Applicable FAA Regs btw [https://www.ecfr.gov/current/title-14/chapter-I/subchapter-D...]
GA aircraft crash every day in the US. They don't make the news outside of aviation circles because only 1-2 people are affected. Often the occupants survive.
Even that is a flawed measure, however. Few people use GA as a replacement for driving. I think in general, an appropriate measure to use is to estimate the (negative or positive) expected DALYs associated with an activity over a lifetime. That said, this measure does (in my opinion) penalize moderately-unhealthy things worse than very risky activities. For example, BASE jumping has a fatality rate of 0.04% per jump. If you do a handful of crazy BASE jumps, that's only a slight DALY difference - very roughly comparable to not brushing or flossing as far as I can tell from this study [0].
The good news is that multirotor drones (even big ones) usually don't need cyclic pitch which is even more complicated than collective pitch, so that makes them less complicated than helicopters, but big drones are still not as mechanically simple as toy drones.
It's kind of like that guy who tied a bunch of little helium balloons to his lawn chair and went flying. It sort of works but it's pointless and dangerous.
That's true for most fixed-wing aircraft, but it's certainly not true for most rotor-wing aircraft. I'd estimate you've got about a second, if you're lucky, between letting go of the cyclic in a Robinson R22 and unrecoverable loss-of-control.
Their very low cost makes them pretty common for schools and instruction in general, but the low inertia (and resultant fatalities early in its operation) was significant enough that the FAA requires a Robinson specific endorsement.
Even in cars where there they do a bunch of gliding (rolling) batteries are just becoming plausible (looking back over time).
It's true that all rechargeable batteries like Li-ion batteries are so far under 1 MJ/kg, which more than 40 times worse than jet fuel just as you say, but it's extremely plausible that Al-air could beat Li-ion by an order of magnitude, and Li-air already does, except for the best Li-ion cells. It's already most of the way there. And fuel cells can beat jet fuel by almost a factor of 3, and for low-power applications they do.
Betavoltaic cells and TEGs have even higher energy density but you can't turn them off, so you need to dissipate the power they produce when you're not using it to fly or whatever. You could build a hybrid system with a large glide ratio that uses chemical batteries for takeoff and a betavoltaic battery or TEG for long-distance cruising, but you might have to only land it on water to keep it from overheating while it was on the ground.
https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery
https://en.wikipedia.org/wiki/Energy_density#In_chemical_rea...
https://en.wikipedia.org/wiki/Energy_density_Extended_Refere...
The other technologies you mention don't seem to be practical for now. I don't think it is reasonable to expect any breakthrough making it to market in the next decade. With specific energy doubling every 10+ yrs, electric flight might be sensible for niche applications (training flights, occasional urban transport for example to the airport) in a few years, but for anything else it'll be several decades realistically.
To put it differently, the reason nobody is flying across the country today on aluminum-air battery power is not that the existing batteries don't have the range; it's that they can fly across the country more cheaply on a combustion-powered jet.
(I think that will continue to be the case even when the combustion fuel is synthesized with electrical energy.)
What do you consider current rates? They improve slowly, maybe 3-7% a year. Last I looked, batteries are so much worse in terms of specific energy than fossile fuels that we're looking at several decades before electric flight becomes practicable (except for very short distances and training flights).
If current rates continue, battery powered jetpacks should be compelling within 60-120 years
While obviously wasteful and goofy, there's always the option of putting an upwards-pointing (i.e. pushing down) thruster at the rear of a jetpack like a lever arm.
To be clear, this is all pie in the sky nonsense, but it's fun to think about. It would still be terribly impractical, but maybe it could be made reliable enough that using it over land would not be immediately fatal to most ordinary people who would want to try it.
Nah, only the Neuralink part.
Similar to just add it to blockchain.
How about a neurolink to the blockchain? Well I guess we have Doge.
> Please don't post insinuations about astroturfing, shilling, bots, brigading, foreign agents and the like.
From the guidelines.
I’m making a prediction of what future grifts will involve.
With the right mental model and control/power systems, it wouldn’t have to be much different from riding a unicycle. Helicopters have similar issues (it’s a bit like balancing a spinning bowling ball on the end of a stick in practice - yet many people are licensed and safe helicopter pilots)
I’m guessing it’s something that not everyone can do, but something a large percentage of people (20%+?) can do if they spent the time learning and it was systematized usefully.
So soldiers that use them would need guns strapped to their feet?
If you look at the photos in the linked article, you'll see that the turbines are on the backpack. It still is tiring for your arms per the article, but for different reasons.
So no Aeroball and Harlem Heroes any time soon :(
https://talkingcomicssite.wordpress.com/2018/04/27/the-compl...
There is a perfectly good flying vehicle that can be flown by an ordinary person with a reasonable amount of training; it's called a powered paraglider. However, it has the disadvantage that it is very large, and if the weather is not favorable, you can't fly.
The analogy with a car would be "road sometimes spontaneously turns into scree", and it would be very hard to design a car that can cope with that.
Drones, in the form of a jetpack.
A little joystick in each hand with DJI levels of KISS, and with the same DJI "Help I'm out of control!" button too. Probably "return to home" too.
We don't/can't have that, because there's no servo-mechanical joints to be controlled in the referenced rocket pack system.
The FAA is amenable to allowing people to operate small personal for non-commercial purposes without a license. If you do not take passengers and do not operate it in time, place, and manner that creates a hazard for others, there's a very real "if you kill your own damn self that's your problem" regulatory mentality.
What you actually need a license for is to exceed speed/weight/fuel limitations designed to ensure these conditions. If you're going for a part 103 ultralight craft, that's 55 knots / 254 pounds / 5 gallons of fuel. Might be hard to design a usable jetpack under these constraints.
Arguably, this could exist, and is a self-stabilizing battery powered drone.
Up is also certain death, if you're not carrying bottled oxygen.
The real issue is, with an 8 minute flight time, it’s good for demonstrations and that’s it.
> Jump really hard and the suit’s jets cut in, amplifying what the suit’s leg “muscles” did, giving you a three-jet shove, the axis of pressure of which passes through your center of mass. So you jump over that house next door. Which makes you come down as fast as you went up . . . which the suit notes through your proximity & closing gear (a sort of simple-minded radar resembling a proximity fuse) and therefore cuts in the jets again just the right amount to cushion your landing without your having to think about it. And that is the beauty of a powered suit: you don’t have to think about it. You don’t have to drive it, fly it, conn it, operate it; you just wear it and it takes orders directly from your muscles and does for you what your muscles are trying to do. This leaves you with your whole mind free to handle your weapons and notice what is going on around you . . . which is supremely important to an infantryman who wants to die in bed. If you load a mud foot down with a lot of gadgets that he has to watch, somebody a lot more simply equipped—say with a stone ax—will sneak up and bash his head in while he is trying to read a vernier.
Recommendations: If you want modern powered-mech suits military action, read The Red Trilogy. If you want a cracking sci-fi novel from the same era but very different politics, “Rebel in Time” is a corker.
I ask because when I read it (way back when), I definitely got the impression this was Heinlein speaking in his own voice / his own opinions.
That's exactly what I'm talking about! Read another book, and he'll be speaking his own voice/opinions, to, but they'll be very different.
On books, Heinlein's must read, in my opinion, is "The Moon is the harsh mistress", "Stranger in a strange land" and "Starship troopers", all three being very different. But the one book I would recommend reading first is his lesser known novel, "The door into summer". It is not groundbreaking, but very warm and charming.
I'd recommend The Moon is a Harsh Mistress which is a romp imho, and also happens to be a better insight into his personal politics.
Also, Have Spacesuit Will Travel, Farmer in the Sky, Stranger in a Strange Land and mostly everything by Heinlein, though there was arguably a bit of a drop in quality towards the late end of his career.
The moon is a harsh mistress is as much a book about strong friendly AI, as one about alternative ways society could be structured to provide continuity and safety if governments fail to provide. The AI aspect is facinating and much deeper than it seems at first. But if you look closely, there are hints all throughout its quite clever, it just does not care about what its doing, it cares about its friend. It reminds me of the treehouse my neighbours kids once made. The kids tried to make it out of ductape, sticks and plank, and their dad helped them, but also snuck out and nailed a few things and support blocks to make it work.
A "separate but equal" civil organization does not mean that there is true equality. Even less so when they do not even pretend to be equal.
The entire book is like an extended version of the quote above.
Of course it’s different with a human involved, but scale up the mavic pro to hold 200 lbs, do a few more iterations, load in a Tesla battery and we’re there.
Something easy-ish to use and safe.
Yeah, probably unrealistic, but nevertheless.
The reality turns out to be different, but, I'd say we were expecting practical personal flight, as seen in video games with jetpacks.
> Now, the flight duration is too short, and the degree of difficulty too great. But this was also the case for the Wright brothers
I think the next step for Jetpacks is to develop automated navigation/stabilization systems. We want a Jetpack for which the normal state is flying at a stable height, then with some kind of 3D joystick we can move steadily up, down, front, back and sideways. I think all of this is currently achievable but too expensive to implement.
Also, the amount of energy required to lift a person is just to high, so until better ways to store energy are developed, the "backpack" form factor for storing energy will not cut it for practical flights.
Just give me hyperloop tunnels to overlap subways and freeways and I am set. Especially with better bike lanes.
Yes, you could. But that’s not actually an argument that jet packs will follow a same development path, it’s just survivor bias in action.
That guy is an actual Royal Marine Commando - he's not cosplaying.
And a quick demo doesn't do a good job of showing fit for purpose either. Maybe performance.
See this video where one of the corridor crew members participates in a jetpack training.
https://m.youtube.com/watch?v=-R5xYaqQo4k
I think it's more precise to say that they are currently a toy for the rich.
Was solved for Segways. Just need the third axis and some kind of special emergency landing solution (goo + inflato-ball??).
Didn't an actual Royal Marine do this recently, in a training exercise? https://www.popularmechanics.com/military/aviation/a38748085...
This seems like exactly what we'd expect for a technology this new and dangerous, and is certainly a step farther than "the creator is the only one flying it".
EDIT: Per other comments on this thread, apparently the Royal Marine in question _is_ the creator
Sure, there isn't a killer app for jet packs at the moment, or perhaps ever. They were enabled by miniature-scale turbine engines being developed for other purposes. But you never know - some innovation in control systems, or them turning out to be just perfect for some obscure emergency/military task, they might find a niche beyond stunts and tethered tourist experiences.
Marines storming a ship is an obvious use case where the high cost will be accounted for (i.e. we have a lot of expensive gear for specific purpose) and it's a practical scenario. Coast Guard same. And certainly other forces. If we can get the gear to be very easy to use and practical, it could very much enable a kind of acute mobility.
There's little direct use beyond that, however, the development of the technology could yield other things as we learn to make those little jets cheap, efficient and intelligent.
Those systems could absolutely be deoployed onto drones, which opens up a world of use cases.
Helicopters autogyro, planes glide, balloons (usually) lose their lift slowly.
A jetpack, like a rocket, is a thing that has no business flying. Only a large, heavy-handed impulse of energy allow them to oppose gravity. Without altitude and a parachute, there is no Plan B for a jetpack engine failure, loss of fuel, etc.
I certainly don't think jetpacks are a relevant tool for society outside of really niche use cases. If we don't even trust people to fly small drones around the public safely and without FAA regulation and licensing, in what dreamland would we all be able to fly personal jetpacks to the shops, or even recreationally? There are way cheaper, way safer ways to get airbourne as a private aviation enthusiast, so I can see why jetpacks really don't scratch enough itches to have gained popularity.
Had they a touchscreen as good as iPhone's? Definitely not. Did they had an internet connecting better than iPhone's? Definitely yes because the original iPhone was only 2G.
Anyway, this is only an analogy so let's don't get too much into it.
People don't care about jetpacks because they are crazy dangerous and expensive. This makes them less practical than jumping from a plane with a parachute instead of waiting for it to land.
The question is if they were easy to fly would we need them - the sound and jet blast seem to be a very bad idea when rescuing people from snow and icy mountain rescue conditions and all the military demonstrations I've seen just seem to suggests it's a loud, slow moving target.
But I'd prefer https://www.youtube.com/c/Jetsonaero/videos to a jet pack too :)
if it relies on the person's skill to fly it and has a 5-10 minute max flight time, of course it'll be a niche thing...
The Flyboard people now have the Flyboard Air.[2] This is a real flying hoverboard, powered by what is believed to be a group of model aircraft jet engines. It's not easy to fly. They require 50-100 hours in the water-powered version before attempting the jet-powered version.
It's very cool, but it's for people who find skateboarding stunts too easy.
https://www.youtube.com/watch?v=suHOLFhbwsM is the video for anyone interested
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you have a machine with micro-thrusters (of whatever fuel-source)
It is driven by modern drone tech for stability.
How driven, super simplistic maths for establishing thrust.telemetry.balance...
How the FUCK has this not been solved?
A belt of jets. They fly you without killing or burning you.
We are significantly evolved for this to happen...
Seriously. This is a solvable thing. Do it.