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Old 28th April 2016, 06:46 AM   #41
Tolls
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Originally Posted by Jrrarglblarg View Post
The differences between jet a, diesel, and cowboy lantern kerosene are mostly academic and irrelevant to this discussion.
Oh right.
Wasn't sure whether that affected any calculations about how much you'd need to carry or not....which is why I ignored the flying part and only noted the odd cuts re: landing. And now that Mike! mentions it, the takeoff.

I haven't a scooby when it comes to whether this thing would fly, or how much fuel is needed. The idea that software is allowing it to balance isn't an issue. That sort of thing is used all over the place, so no reason it wouldn't work on something like this.
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Old 28th April 2016, 09:38 AM   #42
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I've tried researching this more, and found some more indications of a hoax. Apparently, the turbine engines used in the Flyboard Air are newly created/invented for this product, yet there are no patents or other information to be found on the design. Also, turbine engines powered by A1/jet fuel are not nearly as responsive as electric motors used in drone quadcopters with regard to fluctuating speed to make the platform more stable, in addition to being far less efficient when one does fluctuate the speed of rotation.

Finally, there are several videos out showing frame by frame how the promo videos have been digitally altered. I've seen filters that show a cable rising up from the flyboard pilot's back, as well as videos that show indications of digital manipulation such as people's heads being cut partially away as the flyboard supposedly flies in front of them.
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Old 28th April 2016, 12:37 PM   #43
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Originally Posted by Dr.Sid View Post
Can you see the plane on commercial airplanes ? They state it's turbine jet engine, not rocket.
Actually there is a spectrum. Engines that produce more power per unit weight tend to waste fuel and produce quite a bit of heat and flame. Much of the thrust is produced by ejected burning fuel, like a rocket Fighter jets tend to have engines like this. At the other end of the spectrum are engines where as much as the heat energy as possible is directed towards turning a turbine. These engines tend to be much larger in diameter. You see these kinds of engines where fuel efficiency is key, such as airliners.

I would expect that the engines on this would require a high thrust to weight ratio.

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Old 28th April 2016, 12:43 PM   #44
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Originally Posted by wareyin View Post
Finally, there are several videos out showing frame by frame how the promo videos have been digitally altered. I've seen filters that show a cable rising up from the flyboard pilot's back, as well as videos that show indications of digital manipulation such as people's heads being cut partially away as the flyboard supposedly flies in front of them.
Just be sure to put your skeptical hat on here. Whenever there is fast motion, and especially when you get effects from heat mirages scrambling adding extra noise, video compression algorithms struggle to keep up. With the motion prediction element of the algorithm, you'll often get portions of an image that are "dragged".
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Old 28th April 2016, 12:50 PM   #45
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Originally Posted by wareyin View Post
Finally, there are several videos out showing frame by frame how the promo videos have been digitally altered. I've seen filters that show a cable rising up from the flyboard pilot's back, as well as videos that show indications of digital manipulation such as people's heads being cut partially away as the flyboard supposedly flies in front of them.
Links?
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Old 28th April 2016, 01:27 PM   #46
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Originally Posted by CynicalSkeptic View Post
Links?
Not able to link YouTube on my phone. I'll try later.
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Old 28th April 2016, 02:19 PM   #47
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I am still not convinced. If there is a jet engine there where is the intake? That should impact the pilot. It must also be a small one, not dour engines. Less than 0.5 meters in length.
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Old 28th April 2016, 04:14 PM   #48
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I don't know where you got the 0.31 HP figure from but it's wrong. There's no way you can produce more than two or three pounds of airborne thrust with that little power - whether you use a turbine or (more efficient at low airspeeds) propeller or even a helicoper-style rotor.

The sort of ultra-large and very slow rotors used by human-powered helicopters might get close, but the hoverboard clearly isn't using those.
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Old 28th April 2016, 04:50 PM   #49
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Originally Posted by ceptimus View Post
I don't know where you got the 0.31 HP figure from but it's wrong. There's no way you can produce more than two or three pounds of airborne thrust with that little power - whether you use a turbine or (more efficient at low airspeeds) propeller or even a helicoper-style rotor.

The sort of ultra-large and very slow rotors used by human-powered helicopters might get close, but the hoverboard clearly isn't using those.
I got the 0.31 figure from converting the existing kWh numbers for the 52 lbf thrust engines mentioned. I realize that the company claims 250 hp, but I cannot find any existing turbine engine with that power at anything less than 10 times the size shown in the video.
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Old 28th April 2016, 05:28 PM   #50
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I don't think that it is a knee-jerk response to simply say that there are a lot of warning flags on this invention just as with the artificial gill. The development of very tiny jets with much, much larger outputs than ever seen before? The lack of visible air intakes? The unescapable need for certain volumes of fuel given the power demands that would not fit on his back given the time of flight capability claimed?

I would add to these concerns: in the first video the person launches with no detectable effect of the down thrust on the launch platform, on their clothing, or on the person standing right next to him, despite the prominent "effects" of this "exhaust" on the water during his overflight (even though he is much higher over the water than over his launch platform) is odd. And there is no evidence, as the thrust increases at launch, of any effect on his stance- no compression at his knees or ankles, no unevenness of thrust on his right vs. left leg, not even minor changes in his balance, etc.

It may or may not be physically possible, but I am very suspicious of inventions that must spectacularly overcome many technical and practical concerns at once. Particularly those in which there is no public ramp-up, but all the problems are suddenly presented to the public as solved at once. High thrust, small turbojets alone would be very valuable commercially for many more conventional products- to hear of such quantum improvements of jets for the first time in a a totally novel application that requires multiple other solutions to work is suspicious indeed.

I am not dismissing it as a possibility. But nor would I invest even $10 in it at this point.
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Old 28th April 2016, 06:06 PM   #51
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Did they claim 10 minutes flight time? Jetpacks are more like 30 seconds, IIRC. They are obviously not carrying 20 times the propellant, so if real it would require some sort of breakthrough.
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Old 28th April 2016, 07:42 PM   #52
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Originally Posted by Marcus View Post
Did they claim 10 minutes flight time? Jetpacks are more like 30 seconds, IIRC. They are obviously not carrying 20 times the propellant, so if real it would require some sort of breakthrough.
Early "jetpacks" were actually rocketpacks. They used hydrogen peroxide as a controllable but not very powerful monopropellant. Hence their limited operating time.
Modern jetpacks use scaled down jet engines. These have two great advantages. One is that that they don't need to carry an oxidizer, they burn their fuel with oxygen from the air. The other is that the mass of exhaust being accelerated downwards to provide lift is also air. It doesn't need to be lifted and supported during the flight. The net result is a much longer flight time.
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Old 28th April 2016, 08:48 PM   #53
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Another piece of evidence that it is fake. Jets are noisy. The two assistants have ear muffs. However the pilot does not. He would be deafened by the noise.
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Old 29th April 2016, 07:03 AM   #54
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Originally Posted by CynicalSkeptic View Post
Links?
Here's one showing the digital cut outs:
some NSFW language

YouTube Video This video is not hosted by the ISF. The ISF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website.
I AGREE


and this one shows the cable:

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I AGREE
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Old 29th April 2016, 07:10 AM   #55
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Originally Posted by Marcus View Post
Did they claim 10 minutes flight time? Jetpacks are more like 30 seconds, IIRC. They are obviously not carrying 20 times the propellant, so if real it would require some sort of breakthrough.
In the 2nd link, they claim 10 minuted flight time, and speeds up to 90mph, but in the 3rd link, the inventor says he hasn't gone faster than 55mph. I find it pretty sad that the "proof" of this being real offered in that third link is...that the inventor claims it is with no further evidence.
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Old 29th April 2016, 07:19 AM   #56
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Originally Posted by rjh01 View Post
Another piece of evidence that it is fake. Jets are noisy. The two assistants have ear muffs. However the pilot does not. He would be deafened by the noise.
1) he's wearing a motorcycle helmet. Those have some noise attenuation just by bulk mass over your ears and prevention of direct contact of outside air with the eardrums.

2) maybe he has earplugs under the helmet, or maybe he doesn't. Not enough data

3) the acoustic output of an RC-sized turbine isn't an unknowable. The two risks for hearing damage are exposure to high frequency, like whining motors and high amplitude white noise, and exposure to percussives, such as guns or dropped lumber. These things would put out hellacious high frequency turbine whine and white noise from thrust, easily attenuated by a helmet (good helmets are designed for this) and/ or disposable earplugs.
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Old 29th April 2016, 08:54 AM   #57
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Originally Posted by Jrrarglblarg View Post
1) he's wearing a motorcycle helmet. Those have some noise attenuation just by bulk mass over your ears and prevention of direct contact of outside air with the eardrums.

2) maybe he has earplugs under the helmet, or maybe he doesn't. Not enough data
Have you ever worn a motorcycle helmet? They are not designed to protect your hearing, nor do they.

Originally Posted by Jrrarglblarg View Post
3) the acoustic output of an RC-sized turbine isn't an unknowable. The two risks for hearing damage are exposure to high frequency, like whining motors and high amplitude white noise, and exposure to percussives, such as guns or dropped lumber. These things would put out hellacious high frequency turbine whine and white noise from thrust, easily attenuated by a helmet (good helmets are designed for this) and/ or disposable earplugs.
These are not RC-sized turbine engines. The most powerful RC turbine I have found is the JetCat P400 series, and they are rated for 116.4 kW (156 hp). Of course, these suck down 43.96 ounces a minute of fuel at max rpm, so for 4 of them on a 10 minute ride, we'd need 13.7 gallons.

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Old 29th April 2016, 08:57 AM   #58
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Yves Rossy flies with four similar-type engines, a similar helmet, and wings. I don't think he's deaf yet.
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Old 29th April 2016, 09:30 AM   #59
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Originally Posted by Trebuchet View Post
Yves Rossy flies with four similar-type engines, a similar helmet, and wings. I don't think he's deaf yet.
Indeed, Rossy uses the JetCat p400s I mentioned earlier. However, he needs 8 gallons of fuel to fly for 10 minutes, and he has a wing providing lift to do it. Vertically taking off, as the Flyboard does, requires more thrust than level flight with a wing. I'd bet that Rossy wears earplugs, and it is entirely possible that the Flyboard pilot is wearing them under his helmet.
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Old 29th April 2016, 09:31 AM   #60
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Originally Posted by Trebuchet View Post
Yves Rossy flies with four similar-type engines, a similar helmet, and wings. I don't think he's deaf yet.

He does have a bloody great wing, which might mean he needs to use less throttle?
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Old 29th April 2016, 09:37 AM   #61
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Yeah, but the board pilot has a safety cable* to, presumably, a helicopter so he's probably not at full throttle either.



*unmentioned, but fairly obvious based on his wearing a harness, radius swinging motion in his flight, and confirmed by Internet sleuths with photoshop filters.
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Old 29th April 2016, 09:46 AM   #62
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Originally Posted by Jrrarglblarg View Post
Yeah, but the board pilot has a safety cable* to, presumably, a helicopter so he's probably not at full throttle either.



*unmentioned, but fairly obvious based on his wearing a harness, radius swinging motion in his flight, and confirmed by Internet sleuths with photoshop filters.
I've been assuming that the "wake" seen on the water under him in the first video is computer-generated, but I wonder if this can relate to the downwash of the helicopter you proposed? My memory suggests that the "wake" was smaller in circumference than that expected for a helicopter, but I will have to revisit the video later.
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Old 29th April 2016, 09:51 AM   #63
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I think there's actual hot down-thrust gasses hitting the water when he's low enough. I think the safety cable is long enough to prevent the down wash from seriously affecting the pilot or the water.
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Old 29th April 2016, 11:05 AM   #64
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Originally Posted by wareyin View Post
Here's one showing the digital cut outs:
some NSFW language

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I AGREE
He's looking at a 240p source video here. A heavily compressed 240p source video. The square blocking he is describing and showing is a common compression artifact. Go into any youtube video where there is a lot of motion, select 240p, and pause. For instance, this one:

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I AGREE


He does point out that in 1:55 at this video, there is clearly something going on:

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That I buy, someone has intentionally applied a square noise filter to the bottom of the board. Either because it's fake and they are trying to hide something, or it's real and they are trying to hide something. It could also be some compression artifact due to the heat mirage on the understand that I'm unaware of, but it doesn't look like one.

Quote:
and this one shows the cable:

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I AGREE
He applied some unspecified filter to the video. I've tried every edge detection and color modification filter I can find and I can't bring out what he's showing in his video. He notably does not say what filter he is applying. One thing you might note is to look at the other videos in these channels. They are all proof of aliens.

Now. I'm not saying this thing is real, I'm just saying is that the "I can tell from some of the pixels and from seeing quite a few shops in my time" thing doesn't really bring much to the table.
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Old 29th April 2016, 11:17 AM   #65
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Originally Posted by RussDill View Post
He's looking at a 240p source video here. A heavily compressed 240p source video. The square blocking he is describing and showing is a common compression artifact. Go into any youtube video where there is a lot of motion, select 240p, and pause. For instance, this one:

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Fair enough, I didn't realize/pay much attention to the resolution he was using.

Originally Posted by RussDill View Post
He does point out that in 1:55 at this video, there is clearly something going on:

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I AGREE


That I buy, someone has intentionally applied a square noise filter to the bottom of the board. Either because it's fake and they are trying to hide something, or it's real and they are trying to hide something. It could also be some compression artifact due to the heat mirage on the understand that I'm unaware of, but it doesn't look like one.



He applied some unspecified filter to the video. I've tried every edge detection and color modification filter I can find and I can't bring out what he's showing in his video. He notably does not say what filter he is applying. One thing you might note is to look at the other videos in these channels. They are all proof of aliens.

Now. I'm not saying this thing is real, I'm just saying is that the "I can tell from some of the pixels and from seeing quite a few shops in my time" thing doesn't really bring much to the table.
I also didn't look at either YouTuber's other videos. Good call, these videos aren't as helpful as I'd though.
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Old 29th April 2016, 05:22 PM   #66
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The whole '1st mission task', 'mission accomplished' storyline screams *bs*. Real engineers would never attempt such a first test flight, and they wouldn't bother trying to film the teenager-movie style video of it. It's fake.

Accuse me of dismissing it unscientifically if you like. Don't bother to come back later and admit you were wrong after the fakery is revealed.
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Old 29th April 2016, 06:05 PM   #67
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I'm just saying that devices of similar size with similar performance existed 50 years ago.
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Old 29th April 2016, 06:49 PM   #68
wareyin
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Originally Posted by Dr.Sid View Post
I'm just saying that devices of similar size with similar performance existed 50 years ago.
We had something that could fly along at 90mph for 10 minutes while carrying a human, all on about 1 liter of fuel 50 years ago? Link?
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Old 29th April 2016, 06:49 PM   #69
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Originally Posted by Dr.Sid View Post
I'm just saying that devices of similar size with similar performance existed 50 years ago.
True! 60 years ago. In Amazing Stories and Analog Science fiction pulps.
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Old 29th April 2016, 09:26 PM   #70
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Originally Posted by rjh01
3)Jets are noisy... He would be deafened by the noise.
RC jet turbines spin at around 100,000rpm, well above hearing range. They can actually sound quieter than RC petrol engines.

Notice how nobody in the video below is wearing earmuffs.

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Quote:
I am still not convinced. If there is a jet engine there where is the intake?
Intakes will be on top, with the jet engines pointing down.

Quote:
Less than 0.5 meters in length.
Jetcat P400 is 355mm long - weighs 3.5kg, generates 40kg thrust at 98,000rpm. 4 x 40kg = 160kg - easily enough to lift the engines, lightweight frame, some fuel and a healthy pilot.


Originally Posted by RussDill
He applied some unspecified filter to the video. I've tried every edge detection and color modification filter I can find and I can't bring out what he's showing in his video. He notably does not say what filter he is applying.
The videos claiming it is a fake are fakes!

Originally Posted by 3point14
He does have a bloody great wing, which might mean he needs to use less throttle?
It's actually a very small wing for the weight it has to carry, which is why he has to fly so fast. You are right though, hovering is the least efficient way to fly.

Originally Posted by wareyin
The most powerful RC turbine I have found is the JetCat P400 series, and they are rated for 116.4 kW (156 hp).
Horsepower is irrelevant. The only thing that matters is thrust.

Quote:
Of course, these suck down 43.96 ounces a minute of fuel at max rpm, so for 4 of them on a 10 minute ride, we'd need 13.7 gallons.
The 10 minute hovering claim may be dubious, but that doesn't mean it's a hoax. In forward flight it would probably be more efficient, even if only using lift from the human body, so it might be able to carry enough fuel for a 10 minute high speed flight.

Quote:
turbine engines powered by A1/jet fuel are not nearly as responsive as electric motors used in drone quadcopters with regard to fluctuating speed
Correct. Jet engines throttle very slowly, which is why they (claim to) use reactors rather than engine speed to stabilize the platform. If it's a fake, at least they thought carefully about how it should be done...

Quote:
Apparently, the turbine engines used in the Flyboard Air are newly created/invented for this product, yet there are no patents or other information to be found on the design.
Many amateurs have made turbines to their own design. Unless your invention is worth at least $1 million - and you have the resources to actually make that much from it - patenting it is probably a waste of time and money. The alternative of keeping the design secret until you are ready to market it is much cheaper and easier.
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Old 29th April 2016, 10:38 PM   #71
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A couple of things jump out at me.

First, we don't see a single filmed sequence more than around six seconds long, which leaves me wondering if what they've actually done is made multiple trips of 10 to 20 seconds duration and edited them together to make it look like a single long trip.

Second, the "mission completed" message at the end of the video claims a flight time of 3:55, but the entire video is only 2:24, so there's at least a minute and a half of claimed flight time edited out.

Third, when he takes off at the start he's wearing some kind of red safety harness. But in the next jump-cut, and for the rest of the video, he's wearing what looks like some kind of red life-vest, not the harness we see at the start. So clearly the highly dramatic take-off sequence is not part of the flight sequence it precedes. It's something they recorded at a different time and edited into it.
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Old 30th April 2016, 01:22 AM   #72
rjh01
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Originally Posted by Roger Ramjets View Post
<snip>

Intakes will be on top, with the jet engines pointing down.
<snip>
I will concede everything except this point. There is no evidence that there are any intakes at the top. In fact, the pilot is standing over where the intakes should be. Would it work if the intakes were on the sides?
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Old 30th April 2016, 06:14 AM   #73
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Originally Posted by rjh01 View Post
I will concede everything except this point. There is no evidence that there are any intakes at the top. In fact, the pilot is standing over where the intakes should be. Would it work if the intakes were on the sides?
Watch the video again. Here's the zapata racing website
http://zapata-racing.com/fr/

The footrests are on the sides and the top deck is covered in mesh.

Another detail:
The harness he is wearing does not have leg loops like a climbing or parachute harness. It has a crotch strap. One would not choose to dangle from a helicopter with such a harness. This makes it seem less likely that the helicopter is picking him up and carrying him around and more likely the board is carrying his weight. The harness most resembles those used in scuba and I would guess is a scuba tank carrier adapted to carry the fuel bladder.

Last edited by Jrrarglblarg; 30th April 2016 at 06:19 AM.
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Old 30th April 2016, 06:18 AM   #74
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Originally Posted by Brian-M View Post
A couple of things jump out at me.

First, we don't see a single filmed sequence more than around six seconds long, which leaves me wondering if what they've actually done is made multiple trips of 10 to 20 seconds duration and edited them together to make it look like a single long trip.
Probably true

Quote:
Second, the "mission completed" message at the end of the video claims a flight time of 3:55, but the entire video is only 2:24, so there's at least a minute and a half of claimed flight time edited out.
Likely

Quote:
Third, when he takes off at the start he's wearing some kind of red safety harness. But in the next jump-cut, and for the rest of the video, he's wearing what looks like some kind of red life-vest, not the harness we see at the start. So clearly the highly dramatic take-off sequence is not part of the flight sequence it precedes. It's something they recorded at a different time and edited into it.
The PFD would be over the harness.


This "test flight" was probably a sequence edited out of a series of individual flights totalling up to their time. They're jet ski racers, not scientists.
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Old 30th April 2016, 06:49 AM   #75
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Originally Posted by Roger Ramjets View Post
Horsepower is irrelevant. The only thing that matters is thrust.
The only reason horsepower is being discussed is because of the inventor's claim of 4 turbine engines with 250 hp each, the entire unit being 1000hp. I've been trying to convert numbers into hp for comparison, because, as you say, hp is an irrelevant number for a turbine engine. They are all rated in thrust, except for these new, 60% more powerful turbines that the Flyboard people have invented.
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Old 30th April 2016, 06:54 AM   #76
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Those numbers seem really sketchy to me, given that one of the first helicopter turbines used in actual flying machines in replacement of piston engines was a single 250hp unit, and 1000hp is significant power for large modern helicopters.
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Old 30th April 2016, 07:12 AM   #77
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So, thrust/weight ratio. For any level of performance above "barely hover with ground effect" the thrust needs to exceed weight of board and rider. Higher ratios will give greater performance. Not sure how to back calculate thrust demonstrated based on flight demonstrated, but that would get us toward an estimate of how powerful the board ostensibly is.

Upthread I mentioned a random RC tubine, somewhat within the physical size constraints of the board. It is rated for 50+ lbs thrust, so 4 would give 200 lbs thrust. Not enough, I think.
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Old 30th April 2016, 07:38 AM   #78
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It should be noted that the power needed to lift a helicopter is much less than that needed to lift the same weight with a lift-jet. Thrust is proportional to the mass of air flowing per second times its velocity. Power is proportional to the mass of air times its velocity squared.
A helicopter generates lift very efficiently by moving a large mass of air quite slowly. A lift-jet has a much smaller effective diameter and so must move a small amount of air very rapidly. Generating a given amount of thrust requires much more power in the lift-jet.
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Old 30th April 2016, 08:37 AM   #79
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That makes sense. It continues to be all about mass and velocity.

I'm just a carpenter. Unlike those posters who decided upthread they already knew everything they needed to know about this, I expect to learn something before the thread is over.
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Old 30th April 2016, 03:10 PM   #80
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Just took another look at the video. At 1:26 there is a brief scene that shows the top of the flyboard. I can see the mesh and he is standing one foot on either side of the mesh. 100 hp is mentioned above. That is 745 Kw. That is a huge volume of air that would moved with that power. A domestic fan would use only a few Watts of power and moves air at a good speed. Now increase that speed by 100+ and you could get very fast air going past the pilot's legs. There is no evidence of this happening. For example at the very least would expect his trousers to be moving.

Edit. Just watched it in Youtube at 25% speed. I could see the trousers for two seconds and they did not move. There is no air intake that goes anywhere near the pilot. QED.
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