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Comment by sandworm101 | Hacker News Reader

>> They are also very high-profile in nature and require a mothership to launch from, such as a helicopter, or at least a very high point to leap from.

No. Yves "Jetman" Rossi's design can now launch from a standing position on the ground. It is able to launch, hover, transition to forward flight and zoom-climb to several thousand feet. Other than the landing, which is currently still via parachute ... ironman.

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Wow - so he can - here's a video https://youtu.be/lK75XLUIKUk?t=8

Whenever I watch this video and the other jetman videos I can't help but try to find anomalies or something wrong in the video to somehow try and prove that it is CGI (which I know it's not).

Same. I studied aerospace engineering and know that small-scale jetpack flight is possible to do, and yet I cannot help but scan for weird lighting changes or lens incongruities whenever I see a video. It's so insane to see these things.

How does this not burn his legs off?

Would love if someone could answer this or knows of a video that explains jetpacks well

His titanium legs are the real story here

Bypass ratio and entrainment. Most of the air coming through is cool, so the overall air is merely hot, rather than “melts your legs”.

From another viewpoint: people fly turbine-powered model aircraft all the time. Why wouldn't you believe it?

Well for one, where is the fuel? Seems like it would take a tremendous amount of fuel and there are no visible fuel tanks on the jetpack.

It's probably in the wing/back thing.

That depends on how long you want to fly for.

Inside the wing is logical, it's pretty thick and planes have it there as well.

They only have a flight time of about two minutes. It appears longer because they stitch together clips strategically.

Edit: It appears that I confused Vince Reffet with another "jetpack guy" - Richard Browning. The number was for Browning's device. But although you could get more airtime by adding wings, the overall point still stands - the flights are relatively short.

They glide for most of the flight.

Those turbine-powered models aren't carrying 100+ kg of payload?

These rc model turbines pull 20+ kg thrust. In the video he uses turbines noticeably larger, in 50-60kg class. Granted such small turbines have low efficiency - low compression - so they burn 0.2kg fuel per 10 kg thrust per minute. Thus 4kg per minute for 200kg total weight of which fuel is 60kg at best, thus 15 minutes hover at best.

Once it becomes more popular we'll get turbofans, and that will improve the efficiency.

That lines up pretty well with the demonstrated performance of these setups, I think they all have ~15min flying time.

Can't wait for the turbofan versions! :D

How heavy of a battery would you need to power these with enough electricity to lift an adult human, think like a drone on steroids...

Lift for how long?

https://www.tmotoruavdrone.com/product-detail/48968207323300...

Looks like the motor you need. 25KW

And you'd need four of those, I'd guess... so 100kW or so.

with 57inch props - large beasts though so it would be a personal helicopter style suit (https://en.wikipedia.org/wiki/Martin_Jetpack) not true jetpack - it makes 94kg thrust at 23kw, so 2 of them is enough with 60kg/7kwh battery making for 9 minutes of hover (though full discharge is truly bad for the batteries).

Think its this one pretty much

>Thrust 395 Newton ( 39,5 Kg) http://modelaircraftcompany.com/newshop/en/home/89-jetcat-p4...

four of them so about 158 kg thrust total? It's impressive how well they work for what seems quite a simple and relatively inexpensive device.

You might like this one: https://www.youtube.com/watch?v=nj-Iwv5NJKg

Took me a few goes to realize that psychedelic alien ribbon sidescrolling at the end is in fact a river https://i.imgur.com/ln61VPZ.mp4

Why is the parallax so crazy?

What is the behind/top?

I'd love to know the answer. Also, turns out it's not a river but a "swoop pond":

https://goo.gl/maps/pSZVqNJatFoyY6ge9

https://i.imgur.com/MkFmo5v.png

https://www.youtube.com/watch?v=plqEYjIcOow

(bonus blooper https://youtu.be/-rMy8CvHhAw?t=3)

I did.

www.jetman.com has more infos

But nothing on the actual jetpack, like how the engine works.

But here they actually fly next to a jet. So maybe it was those guys.

https://www.youtube.com/watch?v=_VPvKl6ezyc&feature=emb_rel_...

I can imagine a next heist movie.

There's a how the engine works / is made video here https://youtu.be/oYpG0HDcFsA which I think is a similar model to the Jetcat P400 Wikipedia says the jetpack uses.

Interesting TED talk from nearly a decade ago (before VTOL): https://www.youtube.com/watch?v=x2sT9KoII_M

Even if it's not Rossi, whose design has been years in the making, I think a copycat is most likely here. Rossi's wing operates at 4000+ feet and 189mph, which is comparable to jets slowing down on long final. Those hobby jet engines are very expensive but off the shelf, and anyone can build a wing in their garage. The FAA would classify it as an aircraft (already has), and would like to talk to this operator.

I think you can rule out the multirotor bathtubs for now.

It is also odd that they said "in a jetpack" rather than wearing or riding on/under a jetpack. Might this also be a very small but conventional aircraft? Might it be a mannequin mounted inside a smaller drone? Size gets distorted in these situations.

(FYI those hobby jets are one option, but there are considerably more capable small jets available, mostly used for cruise missiles and heavy drones.)

Yeah, that's plausible too.

"in a jetpack" is just a colloquial way of saying "wearing a jetpack". other examples of this type of language include:

"Do you see that man in the suit over there?"

"the suspect in body armor was described as being 6 feet tall."

"man in an orange shirt" is the title of a popular pbs show.

etc etc etc.

Airline pilots typically earn their 1500-hour minimum for their license in "small but conventional aircraft" so the odds of them mistaking one for a jetpack is approximately zero.

And I probably have 5000+ hours driving cars. That doesn't mean I don't occasionally confuse one type of road vehicle for another, especially when dealing with odd/rare types.

You often confuse motorcycles for cars?

At night, sure. Many times I've met a car with a broken headlight, only realizing it's not a motorcycle as we're passing. I don't know if this happened at night, but visibility can be reduced for other reasons as well.

In those cases were you certain what you saw was a motorcycle before realizing otherwise? Or did you wait until you passed to be sure?

This one is scary to me, as a motorcycle rider. The other one that’s not fun: some motorcycles have two separate headlights on the front (low and high beams) and can be wired so that both can be on at once. What are you looking at? A car that’s really far away or a motorcycle that’s really close?

Please watch out for motorcyclists. The blindness people have for us is astonishing. And terrifying.

I've had that on a bicycle. The bike had two small side by side halogens on the handlebars, I was on a main road when a car pulled straight out of a side turning and into the side of me. I released afterwards he'd glanced down the road, seen two small lights and assumed it was a car far enough away for him to pull out.

On motorbikes I've had drivers in side roads look me in the eye and then pull out. On occasion I've ended up having words, and it's always "Sorry mate I didn't see you".

>it's always "Sorry mate I didn't see you".

Ah, the SMIDSY: https://www.youtube.com/watch?v=eqQBubilSXU&t=387s

That video covers the optical illusion that leads to it and what motorcycles can do.

Well yeah, when you remove 99% of the visual information it can be hard to tell if it's a motorcycle.

I do. Those 3 wheel cars/bikes in California...

Would they confuse two particular models of twin-engine piston Cessna? Maybe (but still, probably not).

Will they confuse a seaplane for a blimp? No.

Or report a weather balloon as a UFO? Or see a plastic bag and report it as a drone? Or try to land on the taxiway thinking it is a runway? Such mistakes happen regularly. Given the lack of photography in this case, I lean towards misidentification rather than a rocketman on approach to LAX.

"There's a guy on rollerskates doing 85 on the freeway... oh my bad, it's actually a Ford Fiesta."

There’s at least one video out there of a ‘flying inflatable doll’ attached to a drone. Could be something like that...

At this point, this feels like the most correct speculation.

“I’ve got a phone number for you to write down. Are you ready to record it?”

“Uh...no?”

I imagine a jet pack forces some interesting takes on related technology that pilots are used to having access to when in a cockpit.

For the non-pilots: if ATC gives you a phone number to call after you land, it means you really screwed up. (It's the number for the supervisor, who is thinking about filing a "pilot deviation report" with the FAA.)

The pilots I know describe these calls informally as,

"Mr. Braithwaite, would you step into my office? Bring your license, and a match."

This thread spurred me to listen to some clips, and I just happened across an 'I'll give you the number when you're ready to copy' example:

https://youtube.com/watch?v=mUSUXnr4dSo

<dj kahlid>Another one</dj kahlid>

https://youtu.be/OrRRMoDC_jA

Zapata’s Flyboard Air has much the same capabilities, as doors the Gravity Industries suit.

Seem not, maximum 100 mph (edit: for flyboard. Gravity Industries max is 84 mph)

https://atlanticflyboard.com/flyboard-air

https://gravity.co/experience/

Oh cmon, 16mph difference in top speed is still "much the same".

Yves Rossy's wing: Optimized for forward flight, has VTOL capability, bulky.

Zapata's flyboard: Good middle ground, VTOL with decent speed, restricts ground movement.

Gravity jetsuit: Optimized for hovering, lightweight, can walk in it.

They're all doing much the same thing though, strap some jets onto a human and allow them to fly with VTOL.

a 400N jet engine is now only 6000$. Building a wing with a TWR > 1.0 would only cost about 18 000$ in engines, which is really not that much.

You don't need a TWR anywhere near 1.0. You need that to take off vertically, but if you are willing to jump out of a helicopter you can probably get away with TWRs closer to 0.35 to maintain level flight.

Yes, indeed, but a jetpack specifically refers to a device that is able to hover and take off vertically. But yes, you could make it even cheaper and lighter then, but would need something to help you take off.

Even the Helicopter may not be necessary if you can start with a BASE jump. Or set up a catapult.

Preferably an ACME catapult.

No. Their products are terrible, please, just trust me, I've tried them all.

If things go poorly, just open your umbrella.

Or a kite!

You could use droppable skids or wheels for takeoff, if you don't mind enduring flight at, what, 60 knots at least, in ground effect, with your nose about a foot away from the runway. I can't imagine any sane person doing that, but this guy would probably have had the time of his life.

But you have to have a helicopter pilot around who don’t know it’s not okay you do it, which basically has zero chance.

The full paragraph shows they aren't necessarily referring to Rossi's design not being able to launch from a standing position, but the newer generation of jetpacks in general. It's not very clearly written though, and does make it easy to assume they are referring to Rossi's jetpack along with the others they are lumping together.

There are a number of new jetpack-like designs that are remarkably capable, but all have very limited range and most have only very low-altitude flight envelopes. Yves "Jetman" Rossi's winged jetpack is definitely capable of such a feat, but his flights have always occurred under highly controlled and well-coordinated circumstances and in sanitized airspace. They are also very high-profile in nature and require a mothership to launch from, such as a helicopter, or at least a very high point to leap from.

Source?

https://www.youtube.com/watch?v=nj-Iwv5NJKg

https://www.cnn.com/2020/02/17/tech/jetman-dubai-trnd/index....

"The achievement occurred last Friday, when Jetman pilot Vince Reffett took off from a standing start on the runway at Skydive Dubai in the United Arab Emirates and then flew up to nearly 6,000 feet in altitude. He demonstrated the ability to hover, stop, turn and maneuver."

https://www.youtube.com/watch?v=de_YJzKeGKU

Go to about 3 minutes in to see the take off from standing and continuing to hover.

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