The Truth About New Jet Pack Hype

An anonymous reader writes "This week a sub-$100,000 rocket belt was unveiled and will be on sale this summer, but that's the sad thing: it's still not a real jet pack. Here's a fascinating inside look at the human-flight industry, full of law-suit scandals, technical difficulties, fuel-economy woes and endless delays. The good news? It all points to the next generation of rocketeer research, with real applications for medical rescue and military technology actually coming on the horizon. From the article: 'With a little patience, and a little funding, we could actually have the pleasure of grumbling over regulatory issues we never dreamed possible. Like being limited to specific kinds of air strips, because the jet strapped to your back is classified by the FAA as an ultralight. Or being required to wear a ballistic parachute, because Amarena's Thunderjet design could reach altitudes as high as 10,000 feet (and, for the record, speeds of up to 160 mph, provided someone can solve wind-resistance issues).'"

Jetpacks are just a bad idea

[elrous0 (869638)]

The problem with the "Jet pack" is that it is an inherently foolish and inefficient idea. That much power, in that small a space, with that many stability issues makes for a nasty combo. Lifting ANY aircaft straight up off the ground and landing if softly in the same way is VERY tricky, even for a well-trained human operator (ever wonder why helicopter autopilots are so rare?). Trying do do that with a small mechanism that can fit on or be carried around by a single human is even more tricky. With tolerances that tight, the slighest windgust or miscalculation could send your jetpack spirally helplessesly out of control as you plummet to the ground.

Just because it looks cool in a Bond movie doesn't mean that it will ever be practical in real life.

Re:Jetpacks are just a bad idea

[Harmonious Botch (921977)]

And there is the noise. I've been within 100 yards of one in operation, and conversation with the person next to me was impossible. They really are not fit for urban areas.

Re:Jetpacks are just a bad idea

[veganboyjosh (896761)]

I wonder how different the parent post is from what people had to say when they first heard internal combustion engines...

Re:Jetpacks are just a bad idea

[by Anonymous Coward]

I wonder how different the parent post is from what people had to say when they first heard internal combustion engines...

As seen on the bulletin board in a small English town:

> First!!1!

> I, for one, welcome our new internally combusted overlords.

> The problem with the "internal combustion engine" is that it is an inherently foolish and inefficient idea. That much power, in that small a space, with a highly inflammable fuel makes for a nasty combo. Creating that many small controlled explosions can be very tricky, even for a well-trained human operator.

> And there is the noise. I've been within 100 yards of one in operation, and conversation with the person next to me was impossible. They really are not fit for urban areas.

Re:

[Harmonious Botch (921977)]

Internal combustion engines can be muffled with only minor losses of power output, for the noise comes out of one place ( the exhaust manifold ) and the power comes out in a second place ( the drive shaft ). But a jet pack, the power and the noise both come from the same place, and it is difficult to cut noise without substantially cutting power.

Furthermore, the most successful noise-limiting devices on any jet - I'm thinking passby fans on turbines - adds a great deal of weight. On a jetliner this ca

Re:Jetpacks are just a bad idea

[AndersOSU (873247)]

Decreasing jet noise is in fact very difficult, but it is also a major area of research in mechanical engineering departments across the country.

No, unfortunately this massive research thrust isn't aimed at making jet packs more practical, but rest assured, gains in reducing aircraft jet noise could be applied to jet packs.

The noise a jet makes is the result of turbulent mixing of the high speed jet with the low speed surrounding air. Some solutions are simple, like the chevron edges on the Boeing 787 [wikipedia.org] others are a bit more complicated involving heating, cooling, or electrically charging the exiting jet. The goal being always to make the mixing of the jet and surrounding air less turbulent. Suffice to say you're not likely to have a picnic next to an operating jet engine anytime soon, but it is an active area of research.

Re:

[Jeff DeMaagd (2015)]

A lot of people aren't liking the noise of jet aircraft, which is still pretty loud despite advancements in noise reduction. I can't imagine a whole lot of people liking to wake up to the rumble of a 130+ dB jet pack being fired in their neighbor's driveway.

Re:

[Ced_Ex (789138)]

I'd figure urban areas would be perfect for something like this. Just don't use the jetpack for sustained flight, but more as a "jump pack" to get you up and across rooftops, escaping alleyways and such.

Re:

[Applekid (993327)]

I'd rather have some kind of liquid turned cabling on release... like a "spider's web" that I could "fling" to attach to objects and use that to propel myself through the city.

People would call me The Human Spider.

Re:Jetpacks are just a bad idea

[dzfoo (772245)]

I'm pretty sure there's prior art on that. People call him Spider-Guy, or something.

      -dZ.

Re:

[morgan_greywolf (835522)]

Stuff that's really, really cool is only occasionally very practical.

Re:Jetpacks are just a bad idea

[yog (19073)]

These are technical problems that can be fixed. Put in a gyro and a directional laser and a computer to control it all and you're good to go. Maybe radar and collision avoidance software as well. You shouldn't have to worry about navigating around other objects in the air; your jet pack will have all the smarts it needs under the hood to take care of such things.

As for noise, put a muffler on the jet. Of course, a Harley jet pack would probably not come with one.

I would love one of these. I am so sick of being forced to commute along this predetermined, crowded and narrow little route along with hundreds of thousands of others every day. All that tension, stress, and road rage, not to mention the speed traps. It is so dangerous and inefficient. It would be simpler, faster, and safer to just hop the 25 miles to my destination. And so much more fun.

Just imagine a city full of these devices. People wouldn't need ground garages anymore. Streets could be dug up and replanted to reverse global warming and beautify the city (but leave enough for bike lanes). No more stoplights, no more running over pedestrians.

Bring'em on!

Re:

[jdigriz (676802)]

>Just imagine a city full of these devices. People wouldn't need ground garages anymore. Streets could be dug up and replanted to reverse global warming and beautify the city (but >leave enough for bike lanes). No more stoplights, no more running over pedestrians.

Don't be ridiculous, how are people going to bring home groceries with a jet pack? Or a new flatscreen tv? Or a sheet of plywood? Where would you fit the baby seat for taking the little ones to the grandparents? Commuting to work in a thu

Re:

[Dancindan84 (1056246)]

Put in a gyro and a directional laser and a computer to control it all and you're good to go.

This program has performed an illegal operation and will be shut down.
If the problem persists, contact the program vendor.

"*&^%!! REBOOOooo...___"

Re:Jetpacks are just a bad idea

[somersault (912633)]

All that tension, stress, and road rage, not to mention the speed traps. It is so dangerous and inefficient.

Absolutely correct. All you should really need for jetpack commutes in busy airspace is a jousting pole, a good helmet, and perhaps some air to air missiles

Re:

[cayenne8 (626475)]

"You could move so that you work someplace reasonably near where you live. I put a dollar value (tens of thousands a year) on that, plus the commute time."

Some of us prefer to live in nicer/safer neighborhoods. And people that have kids...often want to live where their kids are in the better school districts (if not in private school). That and some others...like having some 'elbow room' where they live, and don't wanna be cramped up next to someone else....a nice yard or even a good plot of land is nice

Re:Jetpacks are just a bad idea

[starfishsystems (834319)]

Yep. Anything short of nicely modulated antigravity is a non-starter for me. Let's see, why is that? Because even the kinetic energy of my own body falling from my own height can be enough to cause permanent injury? Or because superheated gases sufficient for lift are being generated immediately next to me?

Re:Jetpacks are just a bad idea

[192939495969798999 (58312)]

Yeah, ever play that game "Lunar Lander"? Now imagine that if you land wrong, you actually die on the first try. I don't know anyone that landed that thing on the first try, and all it has is dumb little 2-d zigzag mountains. Imagine high-voltage lines, trees,etc. and this thing is a one-way trip to the rube goldberg/darwin award winner's list... the most scientifically advanced way to do something extremely risky.

Re:

[trolltalk.com (1108067)]

>>"Plus that stupid lander couldn't even land 10 degrees off the normal or it would crash, but humans tend to be able to move their legs around to compensate for that kind of thing. "

Nobody ever broke a leg when parachute jumping - they all did it when hitting the ground | tree | whatever.

Insensitive clod

[sam_paris (919837)]

You insensitive clod, you just killed my dreams of being the rocketeer [wikipedia.org]

:'(

Re:

[somersault (912633)]

That's completely accurate. Which is why I have my rockets strapped to my feet, whose stability issues I solved around the age of 1 years old

-- Iron Man

It is possible to get it right...

[mcrbids (148650)]

In case you haven't seen it before, you outta take a look at the real jet-man [youtube.com]. No, I'm not kidding. Know your limitations and work with them!

BTW: this guy is FREAKIN NUTZS but I sure wish I had cajones like his - this would be such a RIP!!!!

It's all fun and games until

[unassimilatible (225662)]

you get behind some asshole on his cellphone.

old school jet-pack movies

[fifedrum (611338)]

Two fun facts about this project that were glossed over in the old school movies of these things in action are the NOISE and the short flight times.

The TV series Wings covered the first generation of these jet packs and broke my heart when they revealed the true story behind the promotional movies. The pilot wasn't flying for the whole movie, of course, the film crew filmed a few seconds of flight, the pilot would land, refuel and the whole process was repeated and pasted together in post-production. They also dubbed new sounds over the outrageous screech/howl the original packs made.

Watching the film as a kid, I clearly remember thinking there's no way the thing could fly for that long, but the excitement of seeing a guy fly through the woods overcame my skepticism. Clearly though, even with the new films and fuels, we have the same jet pack, the same limited range, the same ear shattering exhaust note. Nothing new IMO.

You Said It

[Jane Q. Public (1010737)]

You can only store so much energy in a package that is liftable by a human being. That has always been, and has remained, their biggest practical failing. A jet or rocket pack that only gives you even 10 or 20 minutes of flight time (much less the more-typical 20 seconds), is just not very practical.

Imagine a pair of these in the trunk

[Babu 'God' Hoover (1213422)]

of your flying car. You could go anywhere!

Re:

[superpulpsicle (533373)]

1. Segway (done)
2. Jet pack (done)
3. Back to the future hoverboard (next)
4. Wonder women invisible plane (next)

Re:

[Pojut (1027544)]

The Back to the Future hoverboard is by far the most fun sounding one on that list:-) I loved that thing!

Re:

[jandrese (485)]

The invisible plane was always an odd accessory IMHO. It's stealthier than a regular plane, but you still have the fully visible squatting woman zipping through the air. Plus, it's gotta be harder to fly when you can't see the controls (or readouts!). And lord help you if you forget where you parked it. Plus, it's a public nuisance to park it anywhere there might be people. The last thing WW needs is some jogger getting a concussion from running smack into her invisible jet head first.

Re:

[Jason Levine (196982)]

Not to mention the embarrassment if you need to use the invisible bathroom. (Cue Family Guy quote.)

same problems as hovercraft

[rcpitt (711863)]

When we had a service here in Vancouver the initial problem was that if it was classified as a boat it was not allowed to go faster than 15 knots in the harbour -

and if classified as an airplane it was not allowed to fly under the Lions Gate bridge.

Some technologies simply don't fit in our pre-conceived systems.

Think of the problems we'll have when we finally crack the problem of personal anti-gravity for our vehicles ;)

soccor moms

[BigJClark (1226554)]

I just had a mental image of soccor moms firing themselves into walls at biblical porportions, drinking a latte, chatting on the cel phone,

I hope there is an IQ minimum *shudder*

Re:soccor moms

[4D6963 (933028)]

I hope there is an IQ minimum

Nah, IQ tests are too long to pass. Would be much quicker to ask people to spell out "soccer" instead.

Damn the parachute?

[fahrbot-bot (874524)]

Or being required to wear a ballistic parachute, because Amarena's Thunderjet design could reach altitudes as high as 10,000 feet.

Or any "reasonable" height for that matter. Jet pack use does not fail gracefully. No glide ratios or gyroscopic descents, just Ahhhhhh... splat. A parachute sounds like a fairly good idea here.

Re:Damn the parachute?

[rwyoder (759998)]

Or being required to wear a ballistic parachute, because Amarena's Thunderjet design could reach altitudes as high as 10,000 feet. Or any "reasonable" height for that matter. Jet pack use does not fail gracefully. No glide ratios or gyroscopic descents, just Ahhhhhh... splat. A parachute sounds like a fairly good idea here.

To restate what he is saying:

• What is the powerplant failure mode of a fixed-wing a/c? It becomes a glider.
• What is the powerplant failure mode of a rotary-wing a/c? It becomes an auto-gyro.
• What is the powerplant failure mode of a jet pack? It becomes a large rock.

The flying car concept (based on ducted fans) has the same fatal flaw.

Wait, solving what?

[jesdynf (42915)]

"Solving" wind resistance? Golly gee, that sounds like a great idea. Maybe after that's in the bag, we'll "solve" the energy it takes to boost an object into orbit, or we'll "solve" the atmosphere lowering the power yield of terrestrial solar panels.

Bah! Wind Resistance Issues

[Phoenix666 (184391)]

I solve wind resistance issues by coating myself with astroglide.

Re:Bah! Wind Resistance Issues

[Overzeetop (214511)]

Who let Richard Gere's gerbil post to slashdot?

"...regulatory issues ..."

[Tim Ward (514198)]

Including, please, banning such toys from any and all airspace that anyone with a proper pilot's licence might want to fly in. I've had one near miss with a toy already and that's enough thanks.

(OK, it was just a child's balloon, and I didn't hit it. But I really don't want to come across untrained idiots who can take my aircraft out of the sky if I hit them.)

Why is it "not a real jet pack?"

[randyest (589159)]

It looks like a jet pack. It's a pack, on the guy's back, and it flies -- apparently with some kind of jet-like propulsion system. Neither article appears to answer this question that the summary gives as axiomatic. Anyone know?

Re:Why is it "not a real jet pack?"

[Frosty Piss (770223)]

A jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's third law of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets, but in common usage, the term generally refers to a gas turbine Brayton cycle engine, an engine with a rotary compressor powered by a turbine, with the leftover power providing thrust. Jet engines are so familiar to the modern world that gas turbines are sometimes mistakenly referred to as a particular application of a jet engine, rather than the other way around. Most jet engines are internal combustion engines but non combusting forms exist also.

-- Wikipedia

Sounds like a jet pack to me.

Re:

[randyest (589159)]

Wait, sorry -- I found it:

all models on the verge of availability are, in fact, jet-free and called, officially, rocket belts.

OK, I guess that's technically right. But is that really a "sad thing" that makes any real difference, or just splitting hairs? I'll take any kind of personally-mounted flying device without bitching about the technical means of propulsion.

Re:

[Carnildo (712617)]

OK, I guess that's technically right. But is that really a "sad thing" that makes any real difference, or just splitting hairs? I'll take any kind of personally-mounted flying device without bitching about the technical means of propulsion.

A rocket belt needs to carry its own oxidizer and reaction mass. A jetpack gets the oxidizer and reaction mass from the atmosphere. The difference in fuel economy is incredible.

Another difference is that a jetpack is regulated as an aircraft (specifically, an ultralight

Re:

[element-o.p. (939033)]

Short answer -- a jet uses outside air as the oxidizer. A rocket carries an oxidizer with it. These devices carry H2O2 in a tank to use as an oxidizer. Therefore, this is a rocket pack, not a jet pack.

I suspect they are using rockets rather than jets because a jet requires a series of turbines to compress the air for combustion, but the (liquid) fuel and oxidizer are pumped into the rocket engine, making the rocket engines simpler and lighter.

All I know

[DRAGONWEEZEL (125809)]

is that I could really use a Jet pack to get the aerobird swift out of a tree. It's about 75ft up, and I tried the wrist rocket / 65lb uglywire(p.s., it's more like 25lb) method to yank it out w/o any success.

Anyone know where I can just "borrow" a rocket belt in the south puget sound area?

More (better) info on jetpacks

[DrBuzzo (913503)]

Ahem... Not to be a complete self-promoting spammer or anything, but I wrote a very extensive article about jet packs and the feasibility thereof some time ago which includes information on recent developments and historical context. Oh yeah, and slashdot didn't seem to want to run it. So if anyone cares it can be found here: http://depletedcranium.com/?p=103 [depletedcranium.com]


(Yes, I am slightly bitter considering the amount of work that went into it)

Jetpacks and Math don't mix?

[Phat_Tony (661117)]

from the article:

"The number of companies looking to sell them to private consumers has increased by as much as 33 percent in the last week alone... while last year there were two commercial rocket-belt manufacturers... there are now three."

Going from two to three would be a 50% increase, not "as much as 33 percent"

Re:

[Stanistani (808333)]

You just need to find someone who is aerodynamically curvaceous.

Re:

[techpawn (969834)]

Wind resistance? Oh come on! This is rocket science! It isn't exactly rocket science here...

Wait...

Re:

[somersault (912633)]

Because we know what could possibly go wrong - it rhymes with flat, and often results in fairly flat objects too.