Rifts Earth Hovercraft: what are they?

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Re: Rifts Earth Hovercraft: what are they?

Unread post by flatline »

ShadowLogan wrote:We are also told in the Skill Description in RUE pg318 & RMB pg29 in the pilot Hovercraft Skill Description "These vehicles can be tricky, because they utilize several air jets and directional thrusters that push the craft along,above the ground, on a cushion of air."

So unless otherwise indicated in the text specifically (like 3G/Naruni for Ex) for specific examples then hovercraft use air jets for propulsion. I guess the real question here should be how they generate those air jets.


So the hover vehicles that exist in canon that don't behave like we expect vectored thrust vehicles to behave and don't have an alternative mechanism described in their description can probably be attributed to authors who didn't think things through.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by eliakon »

flatline wrote:
ShadowLogan wrote:We are also told in the Skill Description in RUE pg318 & RMB pg29 in the pilot Hovercraft Skill Description "These vehicles can be tricky, because they utilize several air jets and directional thrusters that push the craft along,above the ground, on a cushion of air."

So unless otherwise indicated in the text specifically (like 3G/Naruni for Ex) for specific examples then hovercraft use air jets for propulsion. I guess the real question here should be how they generate those air jets.


So the hover vehicles that exist in canon that don't behave like we expect vectored thrust vehicles to behave and don't have an alternative mechanism described in their description can probably be attributed to authors who didn't think things through.

So....basically every piece of technology in Rifts (or virtually every science fiction game or book ever really but Rifts science is notoriously rubbery on par with Star Trek and Star Wars.....which in and of itself suggests that implausible rubber science is not itself a bad thing)
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Re: Rifts Earth Hovercraft: what are they?

Unread post by flatline »

eliakon wrote:
flatline wrote:
ShadowLogan wrote:We are also told in the Skill Description in RUE pg318 & RMB pg29 in the pilot Hovercraft Skill Description "These vehicles can be tricky, because they utilize several air jets and directional thrusters that push the craft along,above the ground, on a cushion of air."

So unless otherwise indicated in the text specifically (like 3G/Naruni for Ex) for specific examples then hovercraft use air jets for propulsion. I guess the real question here should be how they generate those air jets.


So the hover vehicles that exist in canon that don't behave like we expect vectored thrust vehicles to behave and don't have an alternative mechanism described in their description can probably be attributed to authors who didn't think things through.

So....basically every piece of technology in Rifts (or virtually every science fiction game or book ever really but Rifts science is notoriously rubbery on par with Star Trek and Star Wars.....which in and of itself suggests that implausible rubber science is not itself a bad thing)


Well, both Star Trek and Star Wars have artificial gravity, Rifts Earth does not, so in this case, the authors have specifically disqualified the explanation that works in the other two settings.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by eliakon »

flatline wrote:
eliakon wrote:
flatline wrote:
ShadowLogan wrote:We are also told in the Skill Description in RUE pg318 & RMB pg29 in the pilot Hovercraft Skill Description "These vehicles can be tricky, because they utilize several air jets and directional thrusters that push the craft along,above the ground, on a cushion of air."

So unless otherwise indicated in the text specifically (like 3G/Naruni for Ex) for specific examples then hovercraft use air jets for propulsion. I guess the real question here should be how they generate those air jets.


So the hover vehicles that exist in canon that don't behave like we expect vectored thrust vehicles to behave and don't have an alternative mechanism described in their description can probably be attributed to authors who didn't think things through.

So....basically every piece of technology in Rifts (or virtually every science fiction game or book ever really but Rifts science is notoriously rubbery on par with Star Trek and Star Wars.....which in and of itself suggests that implausible rubber science is not itself a bad thing)


Well, both Star Trek and Star Wars have artificial gravity, Rifts Earth does not, so in this case, the authors have specifically disqualified the explanation that works in the other two settings.

The rest of the science in those settings though is really rubbery. There is no way you can try and tell me with a straight face that Star Trek 'Physics' follows any sort of rigid self consistent rules, let alone more than a nodding acquaintance to the real rules.
Star Wars is a bit better but still pretty rubbery around the edges. But they are still wildly popular and considered some of the great science fiction franchises out there. When you get down to it, pretty much every Sci-Fi story is taking liberties with the laws of nature, just some are more egregious than others, and some are more blatant.

<Edit> And remember we still have the lovely rubber science possibility of some sort of spin off of the traction drive, which while not full contra gravity (with all that that entails in the Rifts universe) could plausibly simulate some of its capabilities.
Last edited by eliakon on Sun Jan 24, 2016 12:40 am, edited 1 time in total.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by flatline »

eliakon wrote:The rest of the science in those settings though is really rubbery. There is no way you can try and tell me with a straight face that Star Trek 'Physics' follows any sort of rigid self consistent rules, let alone more than a nodding acquaintance to the real rules.
Star Wars is a bit better but still pretty rubbery around the edges. But they are still wildly popular and considered some of the great science fiction franchises out there. When you get down to it, pretty much every Sci-Fi story is taking liberties with the laws of nature, just some are more egregious than others, and some are more blatant.


I guess I don't understand how this is relevant to the thread.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Blue_Lion »

flatline wrote:
eliakon wrote:The rest of the science in those settings though is really rubbery. There is no way you can try and tell me with a straight face that Star Trek 'Physics' follows any sort of rigid self consistent rules, let alone more than a nodding acquaintance to the real rules.
Star Wars is a bit better but still pretty rubbery around the edges. But they are still wildly popular and considered some of the great science fiction franchises out there. When you get down to it, pretty much every Sci-Fi story is taking liberties with the laws of nature, just some are more egregious than others, and some are more blatant.


I guess I don't understand how this is relevant to the thread.

Think his point is that no sci-fi setting is not always fully explained by modern tech/science. So there is always the possibility that they are using something we are not aware of.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by eliakon »

flatline wrote:
eliakon wrote:The rest of the science in those settings though is really rubbery. There is no way you can try and tell me with a straight face that Star Trek 'Physics' follows any sort of rigid self consistent rules, let alone more than a nodding acquaintance to the real rules.
Star Wars is a bit better but still pretty rubbery around the edges. But they are still wildly popular and considered some of the great science fiction franchises out there. When you get down to it, pretty much every Sci-Fi story is taking liberties with the laws of nature, just some are more egregious than others, and some are more blatant.


I guess I don't understand how this is relevant to the thread.

Because it is only one of part of a series of statements, so isolated by itself no it wouldn't make much sense.
It was there because of my comment that instead of just assuming that the authors were lazy or incompetent and didn't think things through.....that the authors here, like the authors of pretty much every science fiction ever handwaved, used rubber science and only followed things through if they were of interest to the plot at hand. Basically I was saying that claiming that Rifts authors "Didn't do their homework" doesn't really say anything since that is true of basically every science fiction, ever. Secondly I was pointing out that just because other settings have contra-gravity for their hovercraft in no way means that their hovercraft are any more logical than these hovercraft. And third I was offering up a possibility that there could be some other secondary forces at play besides a pure vent that would allow for the venting to still work with out having to have the implausible force levels with out having to simply declare the system as "well its rubber and we can't figure it out" (Traction). Since the problem is that we have come to a place where we are faced with one of two mutually exclusive choices. We can either accept that the drives use only ducted vents....but can also be totally silenced which rules out anything using physics as we know it. Or we can try to keep physics at least in the room but for that we cant have ducted vents be the source of lift and drive for these.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by flatline »

Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by kaid »

flatline wrote:Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.



It seems odd though that it is so consistent across a large number of examples from over a decade of time span in making products and hovercycles being quite especially at low speed has been cannon almost as long as rifts has been around. Seems more sane to just hand wave in some hyper tech golden age gizmo that helps them hover silently given none of the descriptions give that much details on the propulsion than to go back and and retcon so many things to be noisy.

Pretty sure when they were originally making them they saw starwars and went yup we need land speeder things or things like you see in blade runner which are pretty quite at slow speeds but noisy when you open the throttles up.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by ShadowLogan »

flatline wrote:Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.

Well they could put "mufflers" in to counter act the noise. Said system could:
- emit an out of phase sound to cancel out the sound wave generated by the engines (either as a separate system or the way the engines are "tuned" to emit sound, etc)
-some other known technique for silencing/reducing rotary wing aircraft noise (RAH-66 is supposed to be quieter), not sure if sonic book suppression techniques would apply here or not
-have the "silent" aspect as relative (ex 50/50 in WB20)
-shift the sound frequency to outside of the normal range of human hearing, not "silent" per say, but "silent" from certain POV

The velocity the air moves at has an impact on the noise generated by the ducted engines (raw, w/o mufflers or such) and the area of said duct. We can estimate the area of some of the ducts based on the artwork easily enough, but I'm not sure about the velocity since the faster you move the air the less actual air you have to move to generate the same thrust.

If we assume EACH of the ATV's hoverjets (in RUE/RMB) being approx .3m in diameter in the art with a T/W of 1.1 at 1,000kg total mass (vehicle plus payload of pilot and gear) the jets would be exhausting air at ~402m/s, it would emit ~128dB (which pg231 of RMB that has examples on the decibel scale) which put it between jet take off/temp deafening and sonic boom.

(EDIT: revised the velocity to the ATV hoverjets from wild assumption of 10m/s to one that factored in the pressure of the air pre/post-engine to arrive at the velocity given)
Last edited by ShadowLogan on Tue Jan 26, 2016 6:18 pm, edited 1 time in total.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by eliakon »

flatline wrote:Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.

Isn't this though going outside the request you started with?
Since you asked about how Rifts hovercraft work, wouldn't saying "they don't actually" be just as much of a cop out as "they just do"
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Dog_O_War »

flatline wrote:Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.

I did mention that it is possible that you may be able to counter or otherwise restrict the sound to an area, making it basically silent unless you happen to pass directly over someone (in which case the jig is up anyways).
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Re: Rifts Earth Hovercraft: what are they?

Unread post by flatline »

eliakon wrote:
flatline wrote:Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.

Isn't this though going outside the request you started with?
Since you asked about how Rifts hovercraft work, wouldn't saying "they don't actually" be just as much of a cop out as "they just do"


Maybe. Certain elements of what's described may never have a satisfactory answer. I'm not saying that's the case here, but if it is, then a common approach is to throw out the things inconsistent with the model.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by flatline »

ShadowLogan wrote:
flatline wrote:Or we could decide that if it's vectored thrust hovercraft, that it isn't silent despite what the vehicle description says.

Well they could put "mufflers" in to counter act the noise. Said system could:
- emit an out of phase sound to cancel out the sound wave generated by the engines (either as a separate system or the way the engines are "tuned" to emit sound, etc)
-some other known technique for silencing/reducing rotary wing aircraft noise (RAH-66 is supposed to be quieter), not sure if sonic book suppression techniques would apply here or not
-have the "silent" aspect as relative (ex 50/50 in WB20)
-shift the sound frequency to outside of the normal range of human hearing, not "silent" per say, but "silent" from certain POV

The velocity the air moves at has an impact on the noise generated by the ducted engines (raw, w/o mufflers or such) and the area of said duct. We can estimate the area of some of the ducts based on the artwork easily enough, but I'm not sure about the velocity since the faster you move the air the less actual air you have to move to generate the same thrust.

If we assume EACH of the ATV's hoverjets (in RUE/RMB) being approx .3m in diameter in the art with a T/W of 1.1 at 1,000kg total mass (vehicle plus payload of pilot and gear) the jets would be exhausting air at ~402m/s, it would emit ~128dB (which pg231 of RMB that has examples on the decibel scale) which put it between jet take off/temp deafening and sonic boom.

(EDIT: revised the velocity to the ATV hoverjets from wild assumption of 10m/s to one that factored in the pressure of the air pre/post-engine to arrive at the velocity given)


How does that math work? I would love to know how to approximate exhaust velocity. It's interesting that your calculated exhaust velocity is greater than the speed of sound (roughly 340m/s).
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Re: Rifts Earth Hovercraft: what are they?

Unread post by ShadowLogan »

flatline wrote:How does that math work? I would love to know how to approximate exhaust velocity. It's interesting that your calculated exhaust velocity is greater than the speed of sound (roughly 340m/s).

I did a slight math error, I forgot to change the mass into Newtwons for the Hoverbike. The exhaust velocity works out to ~358m/s generating ~126db after this correction.

We know the mass of the ATV hovercycle found in the Rifts Main Book/Ultimate Edition (315kg, I added in 125kg for pilot and gear). We know the approx. diameter of each jet, about the size of the rider's forearm (assuming he's 6ft male) that puts it at 30cm (or .3m) in diameter. Since the platform's lift is purely based on thrust, it has to have a Thrust to Weight ratio of greater than 1.0. I went with 1.1, which IINM is a tad more powerful than the AV-8B Harrier. I calculated the total thrust in Newtons and divided by the total area of the 3 circular jets. This would be the exit pressure.

There is a formula I found to convert pressure values into velocity. We need to know the air pressure before entering the jet and after leaving the jet, along with the density of air. This will yield the velocity, which can be plugged into another formula to calculate the generated noise.

I admit there are a few factors in this examples that are approximations/guesses: T/W ratio value, the actual diameter of the jet exhaust port, and the payload (pilot plus gear)). And I might be wrong in their application of the pressure equation. I'd be more comfortable with rocket equations, which if we assume the engines are nuclear and have an specific impulse comparable to NERVA at Sea level (test article I found info for has 380sec which translates into ~3,700m/s, a typical jet engine has an Isp in 1000s of sec for comparison) that would give us ~175dB of noise from one engine.

The easist way to reduce the noise is to reduce the velocity of the air, which requires that you move more of it at a slower velocity. And to reduce the velocity we have to reduce the area in the above equations (and/or go with different T/W value and "payload mass")

Forumlas used found here:
http://www.engineeringtoolbox.com/ducts ... _1405.html
http://www.engineeringtoolbox.com/jet-d ... _1868.html
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Re: Rifts Earth Hovercraft: what are they?

Unread post by theran_mage »

Hey guys,
I love what everyone's been discussing, this is a great thread.

I'm not sure if you all saw the Hoverboard distance record that was broken this May by Franky Zapata:
http://www.guinnessworldrecords.com/news/2016/4/confirmed-franky-zapata-sets-new-farthest-hoverboard-flight-record-in-france-427011

Personally I think this is the best, current example of how future earth hovercraft will work. No, it does not fly silently and yes, it uses a jet fueled turbine, but it's got a 10,000 foot ceiling and a current top speed of 150mph which, with the exception of the current fuel limitation, puts it in league with most of Rifts' hovercraft.

Mr Zapata is talking about his next steps focusing on safe landings during malfunctions and extending the range. For me, seeing this test really made the hovercycles more tangible.

Also, if anyone recalls, the aforementioned sound-dampening technology that's used on the Ninjaborg might be used to quiet the craft, but I'm gonna stick with hand-wavy science to cover the silent floating thing for now since everyone is very adamant about the no anti-grav technology. It was also mentioned that animals aren't scared by Rifts Hovercraft and I'd remind everyone that animals can get used to a lot (look at deer that eat grass at the side of highways), there are still probably a TON of animals that freak whenever they even hear a hovercraft in the area, but I'd bet a lot of the domesticated animals have had to be around them so much, they're pretty used to ignoring them.

Lastly, for everyone using the artwork as a scientific basis for how the hover tech works, most of the time, neither the writers nor artists have any scientific background and even Kevin isn't always thinking about that level of detail (dust being kicked up when idling) or it just looked better to omit the dust.

You guys really sparked my imagination, thanks for all the insights. :)
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Re: Rifts Earth Hovercraft: what are they?

Unread post by HWalsh »

There might be one way to accomplish it, it would require 3 things that, thankfully, do exist in Rifts.

1: Micronized power generators/reactors that have a phenomenal output. Rifts have these.

2: Megadamage materials that can withstand the heat and strain.

3: Room temperature superconductivity.

If I understand the theory then you could generate lift by exploiting the Lorentz force and thus using the Earth's EM field to create an electromagnetic repulsor. The problem with this idea, however, is that even with proper shielding you'd be creating a massive electromagnetic disturbance.

That having been said...

Using a base principle one could create an atmospheric ionic thruster. This would be quiet, not produce the EM disturbance, and even be relatively cool.

Basically a series of ionic wind thrusters.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by blackwingedheaven »

Why not a combination of electromagnetic repulsion, minor amounts of vectored thrust, and the ionocraft effect? I mean, it's not practical with modern technology because of materials limitations and power needs, but both of those are solved problems on Rifts Earth.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by J_cobbers »

Most of the written material implies jets, or air based thrust rather than some unobtainum type element for propulsion at least. Room temp super conductors or magnetic field generators would still need a surface with a magnetic field to push off of. Star Trek and Star Wars type Artificial or Anti grav / repulsor lift tech hasn't been introduced to Rifts Earth Human Tech societies (though present in the 3 Galaxies and Phase World setting and in the hands of the likes of the Arkhonens in South America and Splugorth in Atlantis). So that really leaves some way of pushing air or some-other means of lift generation.

So yeah apply Occam's Razor, and that leaves you with probably some very sophisticated noise cancelling techniques to keep engine and turbine noise down. I like to think maybe there's a Hunt for the Red October style high speed caterpillar drive for air instead of water. I would assume some hover vehicles are better at this than others, and that there are a variety of techniques being used or not depending on the particular make and model of the hoverbike/craft.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by theran_mage »

Hey guys Greg Diazyk dea scribes the "whisper" system in Rifter 51 as a way to quiet hover cycle engine noise, adapted from pre-rifts silent helicopter technology. It's in the Vehicle creation section Part 2. Page 76 I think.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by kaid »

HWalsh wrote:There might be one way to accomplish it, it would require 3 things that, thankfully, do exist in Rifts.

1: Micronized power generators/reactors that have a phenomenal output. Rifts have these.

2: Megadamage materials that can withstand the heat and strain.

3: Room temperature superconductivity.

If I understand the theory then you could generate lift by exploiting the Lorentz force and thus using the Earth's EM field to create an electromagnetic repulsor. The problem with this idea, however, is that even with proper shielding you'd be creating a massive electromagnetic disturbance.

That having been said...

Using a base principle one could create an atmospheric ionic thruster. This would be quiet, not produce the EM disturbance, and even be relatively cool.

Basically a series of ionic wind thrusters.



Yes the whole ability to have pint sized nuke plants is one huge thing that makes it hard to even guess what would be possible with that tech. With an effectively unlimited power budget you can do a lot of things that right now simply would not work because all the stuff you would need to power them would counter act any thrust force it gives.

Heck with enough power and advanced tech super conductors the repulsive force could literally just be maglev with ducted thrusters to provide the motive force. If the air ducts are not having to keep it suspended then it indeed could be super quiet at low speeds.

A lot of impossible things become possible if one can throw enough power at it from a source that itself is not heavy/bulky.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Froward Firimar »

I'm thinking that a plausible option for the hoverbike technology would be some future form of Superconductor levitation. Superconductors in the bike levitating over the earths magnetic field. This would allow only hovering and not flight, the hovering could be maintained with only an electric current...
This tec would only be on the hoverbike as larger vehicles would be too heavy.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

Froward Firimar wrote:I'm thinking that a plausible option for the hoverbike technology would be some future form of Superconductor levitation. Superconductors in the bike levitating over the earths magnetic field. This would allow only hovering and not flight, the hovering could be maintained with only an electric current...
This tec would only be on the hoverbike as larger vehicles would be too heavy.

Almost certainly the lift force from Earth's magnetic field is not large enough to notice any kind of hover with any known superconductor.

Although it's Rifts, maybe they have some amazingly superdense superconductors. :)

But I reckon stability still is an issue.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Froward Firimar »

Natasha wrote:
Froward Firimar wrote:I'm thinking that a plausible option for the hoverbike technology would be some future form of Superconductor levitation. Superconductors in the bike levitating over the earths magnetic field. This would allow only hovering and not flight, the hovering could be maintained with only an electric current...
This tec would only be on the hoverbike as larger vehicles would be too heavy.

Almost certainly the lift force from Earth's magnetic field is not large enough to notice any kind of hover with any known superconductor.

Although it's Rifts, maybe they have some amazingly superdense superconductors. :)

But I reckon stability still is an issue.


Definitely, stabilizers, propulsion and maneuverability would all be done with other types of thrust.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by ShadowLogan »

Natasha wrote:
Froward Firimar wrote:I'm thinking that a plausible option for the hoverbike technology would be some future form of Superconductor levitation. Superconductors in the bike levitating over the earths magnetic field. This would allow only hovering and not flight, the hovering could be maintained with only an electric current...
This tec would only be on the hoverbike as larger vehicles would be too heavy.

Almost certainly the lift force from Earth's magnetic field is not large enough to notice any kind of hover with any known superconductor.

Although it's Rifts, maybe they have some amazingly superdense superconductors. :)

But I reckon stability still is an issue.

There really is no need to resort to magnetic levitation technologies, the ability to create a hovercraft is certainly doable and was done in the 1950s. In fact this is pretty much what the books state is going on in all but a few cases that call this out. Noise of course is an issue, but certainly one that is manageable without much reaching for super advanced technology either.

The thing with magnetic levitation technology is it allows for launching into orbit, you may or may not need super conductors at all, and really has no upper or minimum size limits (busts the idea of hoverbike only). What it does require, possibly even with superconductors, is a high current density (200,000amps/sq. cm is a figure I've seen, at least connected to a launch vehicle).
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

ShadowLogan wrote:
Natasha wrote:
Froward Firimar wrote:I'm thinking that a plausible option for the hoverbike technology would be some future form of Superconductor levitation. Superconductors in the bike levitating over the earths magnetic field. This would allow only hovering and not flight, the hovering could be maintained with only an electric current...
This tec would only be on the hoverbike as larger vehicles would be too heavy.

Almost certainly the lift force from Earth's magnetic field is not large enough to notice any kind of hover with any known superconductor.

Although it's Rifts, maybe they have some amazingly superdense superconductors. :)

But I reckon stability still is an issue.

There really is no need to resort to magnetic levitation technologies, the ability to create a hovercraft is certainly doable and was done in the 1950s. In fact this is pretty much what the books state is going on in all but a few cases that call this out. Noise of course is an issue, but certainly one that is manageable without much reaching for super advanced technology either.

The thing with magnetic levitation technology is it allows for launching into orbit, you may or may not need super conductors at all, and really has no upper or minimum size limits (busts the idea of hoverbike only). What it does require, possibly even with superconductors, is a high current density (200,000amps/sq. cm is a figure I've seen, at least connected to a launch vehicle).

The magnetic field of earth is way too weak. There are simple experiments to see this. Weigh a magnet on one of its sides and again on the reverse side. Are they the same?
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Re: Rifts Earth Hovercraft: what are they?

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The thing is your magnets have to be able to generate enough force to counter the force of gravity. So you will need a very strong magnet involved, which likely means an electro-magnet (which is lumped into maglev).

Earth's magnetic field may or may not be to weak in the long run for maglev, but we have to remember that magnetic levitation is by the interaction of two magnetic fields pushing each other away. And the force pushing them away has to be sufficient to overcome gravity. So the platform's magnetic field is just as important (if not more so) than the Earth's since it is a factor.
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Re: Rifts Earth Hovercraft: what are they?

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If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.
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Re: Rifts Earth Hovercraft: what are they?

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Natasha wrote:If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.


Not a good comparison there, magnetism drops off rapidly over distance so the fridge magnet is less than a paper's width from the metal giving it vastly greater attractive force than the effect of gravity.

For a magnetic field to suspend something against gravity it requires a suitable force to push against, Earth's magnetic field is way too weak to make that happen which is why what forays we've seen into such things have required the intended track to also generate a powerful magnetic field for the one from the vehicle to push against.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by glitterboy2098 »

the closest you can get is diamagnetic levitation of things like water inside an electromagnet.. good for suspending certain materials inside a stationary device, but useless as a drive. (and since said object is still effected by gravity, more of a laboratory curiosity so far) and that requires some of the most powerful electromagnets every created.
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Re: Rifts Earth Hovercraft: what are they?

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Nightmask wrote:
Natasha wrote:If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.


Not a good comparison there, magnetism drops off rapidly over distance so the fridge magnet is less than a paper's width from the metal giving it vastly greater attractive force than the effect of gravity.

Which is actually my point. The claim was made that not only can you levitate mass, you can generate enough acceleration to launch them into orbit. Of the fundamental forces of nature, gravitation is the weakest far and away. If the strong force is 1, then gravitation is 6 * 10^(-39); that's almost forty 0s before the first non-zero digit. The only way to launch something into orbit with emf is a really long rail gun and a tremendous power source. The system is approximated by parallel current carrying wires. The size of the magnetic field is determined by the length of the rails, the longer the rails the larger the magnetic force. Of course, this is a part of the reason why real rail guns break down after a shot or two.

Nightmask wrote:For a magnetic field to suspend something against gravity it requires a suitable force to push against,

If a magnet is suspending something then it isn't pushing, it's pulling. Consider this experiment. Tie a sewing thread to a needle or paper clip and secure the other end of the thread with tape to a block of wood or plastic. Bring a magnet ever closer and you will levitate the needle. The opposing force is the tension in the thread with a minor contribution from gravitation. There is no push.

glitterboy2098 wrote:the closest you can get is diamagnetic levitation of things like water inside an electromagnet.. good for suspending certain materials inside a stationary device, but useless as a drive. (and since said object is still effected by gravity, more of a laboratory curiosity so far) and that requires some of the most powerful electromagnets every created.

Yes. And this is what Froward Firimar brought up.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by glitterboy2098 »

no it is not natasha. there is a huge difference between put inside a giant cylindrical super conducting electromagnet and being suspended in midair when it is on.. and something that uses the earths magnetic field to fly. Diamagnetism is the natural ability of some materials to "push away" magnetic fields. it is incredibly weak, but when put inside a massive electromagnet configured exactly the right way the "pushing away" can result in an object being suspended in the magnetic field such that it looks to be "flying". you control the spin, angle, and altitude of the object so suspended by altering the shape of the magnetic field around it.

but it only works when your the one generating the magnetic field, because earth's magnetic field is the wrong shape and power** and we're in the wrong place relative to it. and you cannot create diamagnetism artificially (so far.. and figuring out how to do that and amplify the effect would result in a major rewrite of physics)

a variation on diamagnetism is used for those "floating globe" toys (where a diamagnetic material is put onto the item to float, and placed over the center of specially shaped magnetic field), but that tech is useless for hovercraft travel purposes as well. since it would require you to build a physical track. (basically a less efficient maglev train)

** for levitation, depending on the material, you need a field of several tesla's. levetating water needs a 45 tesla field.
earth's magnetic field is only 5 milliTesla's.. so you need 5 million plus times stronger than the earth's magnetic field as measured at the surface. and remember the field gets weaker rapidly as you get farther from the center..
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

Yea. I should have been more precise. Since superconductors are ideal diamagnets, superconductor levitation is diamagnetic levitation.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by ShadowLogan »

Natasha wrote:If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.

The magnet in your case isn't pushing against Earth's magnetic field to overcome gravity in a free-flyer levitation situation. The magnet is interacting with the ferromagnetic material of the fridge though, which allows it to "stick" to the fridge to overcome gravity and not fall to the floor.

We know magnets/electro-magnets can exert a force to overcome gravity and produce levitation effects. However to use Earth's magnetic field to push off of, you will need a much stronger magnetic field involved from the "flyer".

glitterboy2098 wrote:the closest you can get is diamagnetic levitation of things like water inside an electromagnet.. good for suspending certain materials inside a stationary device, but useless as a drive. (and since said object is still effected by gravity, more of a laboratory curiosity so far) and that requires some of the most powerful electromagnets every created.

Maybe not. Aviation Week & Space Technology Dec24,1990 (pg71-3, though only 1/3 of the last page relates) has an article that suggests* a "tripole magnetic field" could be used by a free flying magnetic levitator. Such system also required the 200,000amps/cm^2 and is projected to be capable of reaching orbit.

*I say suggest because I haven't seen any follow up.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

ShadowLogan wrote:
Natasha wrote:If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.

The magnet in your case isn't pushing against Earth's magnetic field to overcome gravity in a free-flyer levitation situation. The magnet is interacting with the ferromagnetic material of the fridge though, which allows it to "stick" to the fridge to overcome gravity and not fall to the floor.

We know magnets/electro-magnets can exert a force to overcome gravity and produce levitation effects. However to use Earth's magnetic field to push off of, you will need a much stronger magnetic field involved from the "flyer".

The same magnet that can stick to a fridge can suck a paper clip off a table from above or below the table. It does this because it is so much more powerful than Earth's magnetic field. It is not pushing off Earth's magnetic field in any scenario. There are simple experiments to show this is the case. You can weigh a magnetic putting the north pole down and then again putting south pole down and you will observe no change in weight; if the magnet were pushing off of Earth's magnetic field, you should see a change in weight. Wave any ferrous metal (like a knife blade) around a magnetic compass and you will see that you can deflect the needle because the knife's magnetic field is stronger than Earth's. A more involved experiment is to wrap some wire around a compass and pass current through it; the needle will deflect some angle at some speed proportional to the current. But the reason is the same, the magnetic field is stronger than Earth's.

The magnet is not pushing against Earth's magnetic field because it is far stronger than Earth's magnetic field. The magnet's magnetic field is simply over powering Earth's magnetic field. However, in the case of superconductor levitation, you can theoretically get there, as has already been covered.

ShadowLogan wrote:
glitterboy2098 wrote:the closest you can get is diamagnetic levitation of things like water inside an electromagnet.. good for suspending certain materials inside a stationary device, but useless as a drive. (and since said object is still effected by gravity, more of a laboratory curiosity so far) and that requires some of the most powerful electromagnets every created.

Maybe not. Aviation Week & Space Technology Dec24,1990 (pg71-3, though only 1/3 of the last page relates) has an article that suggests* a "tripole magnetic field" could be used by a free flying magnetic levitator. Such system also required the 200,000amps/cm^2 and is projected to be capable of reaching orbit.

*I say suggest because I haven't seen any follow up.

That's because a magnetic tripole is absurd and Maxwell's Equations are pretty clear on that. The article is probably talking about some kind of kooky arrangement of this and that which creates what appears to be a magnetic tripole (nothing new since 1990 is a clue) but I am hard pressed to even speculate how they think that could get anything into orbit. It's kind of like that article that gets floated now and again about the free energy engine which violates conservation of momentum and if it worked it could be thought of like a bunch clowns in a car pushing against the doors and windows to make the car go.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by ShadowLogan »

Nothing new since 1990 isn't necessarily a clue for a variety of reasons. (Here is a link to the patent #: https://www.google.com/patents/US4874346) I would point out the guy did get an invitation to demonstrate the thing to NASA (who also evaluated it), which has to say something about the science backing it up.

It is possible to create non-bi-pole magnetic fields, and the wiring layout of the electromagnet is stated to result in a tripole (weather that is an appearance or not is irrelevant, the result is a tripole). Quoting from the above patent writeup: " obeys Ampere's longitudinal force law to indeed produce substantial thrust in the "weak" magnetic field of the earth". If it generates sufficient thrust to lift off, and is applied over a long enough time it will achieve the necessary velocity to reach orbit.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

ShadowLogan wrote:Nothing new since 1990 isn't necessarily a clue for a variety of reasons. (Here is a link to the patent #: https://www.google.com/patents/US4874346) I would point out the guy did get an invitation to demonstrate the thing to NASA (who also evaluated it), which has to say something about the science backing it up.

It is possible to create non-bi-pole magnetic fields, and the wiring layout of the electromagnet is stated to result in a tripole (weather that is an appearance or not is irrelevant, the result is a tripole). Quoting from the above patent writeup: " obeys Ampere's longitudinal force law to indeed produce substantial thrust in the "weak" magnetic field of the earth". If it generates sufficient thrust to lift off, and is applied over a long enough time it will achieve the necessary velocity to reach orbit.

No, it's not always a clue. In this case, however, it is.

Furthermore, it's a patent so all is required is a description of how the contraption might work. It's based on Ampère's longitudinal force law; now I didn't read the whole patent but that throws up some red flags. The Ampère-Maxwell debate flared up in the 1980s which probably explains this patent's date. However, Maxwell's stress explanation seems likely to always win given that it accounts for the effect of longitudinal forces and, of course, to say nothing of the utter success of Einstein's General Relativity Theory.

Note that the clown car engine is said to have been developed by Nasa....
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Nightmask »

Natasha wrote:
ShadowLogan wrote:
Natasha wrote:If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.

The magnet in your case isn't pushing against Earth's magnetic field to overcome gravity in a free-flyer levitation situation. The magnet is interacting with the ferromagnetic material of the fridge though, which allows it to "stick" to the fridge to overcome gravity and not fall to the floor.

We know magnets/electro-magnets can exert a force to overcome gravity and produce levitation effects. However to use Earth's magnetic field to push off of, you will need a much stronger magnetic field involved from the "flyer".

The same magnet that can stick to a fridge can suck a paper clip off a table from above or below the table. It does this because it is so much more powerful than Earth's magnetic field. It is not pushing off Earth's magnetic field in any scenario. There are simple experiments to show this is the case. You can weigh a magnetic putting the north pole down and then again putting south pole down and you will observe no change in weight; if the magnet were pushing off of Earth's magnetic field, you should see a change in weight. Wave any ferrous metal (like a knife blade) around a magnetic compass and you will see that you can deflect the needle because the knife's magnetic field is stronger than Earth's. A more involved experiment is to wrap some wire around a compass and pass current through it; the needle will deflect some angle at some speed proportional to the current. But the reason is the same, the magnetic field is stronger than Earth's.

The magnet is not pushing against Earth's magnetic field because it is far stronger than Earth's magnetic field. The magnet's magnetic field is simply over powering Earth's magnetic field. However, in the case of superconductor levitation, you can theoretically get there, as has already been covered.


You seem to keep ignoring that a hover vehicle that tried to get around via magnetism would perforce have to be PUSHING against Earth's magnetic field and it'd have to push with at least enough strength to counter Earth's gravity and due to how relatively weak Earth's magnetic field is you'd need an enormous field from the vehicle to make it happen. Even if it were theoretically possible said magnetic field would at a minimum be detectable for miles if not far more plus the issue of what such a massive field would have with any ferromagnetic materials in the area and that intense magnetic fields aren't healthy for living organism.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

Nightmask wrote:
Natasha wrote:
ShadowLogan wrote:
Natasha wrote:If you ever stuck a magnet to a fridge and it didn't fall to the floor, then you found one stronger than gravity. If Earth's mag field cannot repel a common magnet, as the experiment I described shows it cannot, it doesn't matter how powerful mine is.

The magnet in your case isn't pushing against Earth's magnetic field to overcome gravity in a free-flyer levitation situation. The magnet is interacting with the ferromagnetic material of the fridge though, which allows it to "stick" to the fridge to overcome gravity and not fall to the floor.

We know magnets/electro-magnets can exert a force to overcome gravity and produce levitation effects. However to use Earth's magnetic field to push off of, you will need a much stronger magnetic field involved from the "flyer".

The same magnet that can stick to a fridge can suck a paper clip off a table from above or below the table. It does this because it is so much more powerful than Earth's magnetic field. It is not pushing off Earth's magnetic field in any scenario. There are simple experiments to show this is the case. You can weigh a magnetic putting the north pole down and then again putting south pole down and you will observe no change in weight; if the magnet were pushing off of Earth's magnetic field, you should see a change in weight. Wave any ferrous metal (like a knife blade) around a magnetic compass and you will see that you can deflect the needle because the knife's magnetic field is stronger than Earth's. A more involved experiment is to wrap some wire around a compass and pass current through it; the needle will deflect some angle at some speed proportional to the current. But the reason is the same, the magnetic field is stronger than Earth's.

The magnet is not pushing against Earth's magnetic field because it is far stronger than Earth's magnetic field. The magnet's magnetic field is simply over powering Earth's magnetic field. However, in the case of superconductor levitation, you can theoretically get there, as has already been covered.


You seem to keep ignoring that a hover vehicle that tried to get around via magnetism would perforce have to be PUSHING against Earth's magnetic field and it'd have to push with at least enough strength to counter Earth's gravity and due to how relatively weak Earth's magnetic field is you'd need an enormous field from the vehicle to make it happen. Even if it were theoretically possible said magnetic field would at a minimum be detectable for miles if not far more plus the issue of what such a massive field would have with any ferromagnetic materials in the area and that intense magnetic fields aren't healthy for living organism.

I'm not ignoring it. I'm explaining why it cannot occur no matter how strong my magnet is. The summary is given in the last paragraph of mine you quoted. Again, making a magnet stronger does not change anything; this can be seen by experimentation.

It is true enough that it has already been covered that diamagnetic levitation with current tech is limited and not possible with Earth's magnetic field; but that was the point of the qualifier "future" when describing a plausible system.

Does your hypothesis have a name I can look up? Or some experiments that I can conduct? If not, we are going to just be repeating ourselves going forward. Either road, I assure you that I'm not ignoring what you're saying.
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Re: Rifts Earth Hovercraft: what are they?

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https://van.physics.illinois.edu/qa/listing.php?id=1027 wrote:That having been said, if you had a really really big magnet, whose field extended over such a large region that the Earth’s field changes noticeably over that region (you might need another Earth-sized bar magnet), then yes, a noticeable force can be produced.


So yes a sufficiently powerful magnet can produce force against the Earth's magnetic field. The key word though is sufficiently, so in theory it can be done. In practice is another matter.

And no a lack of follow up is not telling beyond the technology may not be practical yet for some reason(s).
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Natasha »

ShadowLogan wrote:
https://van.physics.illinois.edu/qa/listing.php?id=1027 wrote:That having been said, if you had a really really big magnet, whose field extended over such a large region that the Earth’s field changes noticeably over that region (you might need another Earth-sized bar magnet), then yes, a noticeable force can be produced.


So yes a sufficiently powerful magnet can produce force against the Earth's magnetic field. The key word though is sufficiently, so in theory it can be done. In practice is another matter.

And no a lack of follow up is not telling beyond the technology may not be practical yet for some reason(s).

Read it again. It's not the strength of the magnetic field, it's the size. I assume that we are not considering using planets as hoverbikes to float around on other planets.

I did say it raises red flags. The Sun could explode tomorrow but it quite likely won't.
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Re: Rifts Earth Hovercraft: what are they?

Unread post by eliakon »

My money is that if there is a super science force involved that is not just the air it is not magnetism but is instead the mysterious Time/Space adhesion technology used in traction drives.
-Its super-science so it allows hand waves
-it is known to be something that golden age civilizations can invent
-it is known to use energy to create movement via a form of reactionless drive

Thus the 'levitation' effect could be Traction based, with the air-jets providing bulk propulsion and steering, possibly Traction assisted. Throw in some white noise/counter sound generators to offset the sound and your good to go.
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Re: Rifts Earth Hovercraft: what are they?

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eliakon wrote:My money is that if there is a super science force involved that is not just the air it is not magnetism but is instead the mysterious Time/Space adhesion technology used in traction drives.
-Its super-science so it allows hand waves
-it is known to be something that golden age civilizations can invent
-it is known to use energy to create movement via a form of reactionless drive

Thus the 'levitation' effect could be Traction based, with the air-jets providing bulk propulsion and steering, possibly Traction assisted. Throw in some white noise/counter sound generators to offset the sound and your good to go.

Is this material from Phase World?
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Re: Rifts Earth Hovercraft: what are they?

Unread post by Shark_Force »

Natasha wrote:
eliakon wrote:My money is that if there is a super science force involved that is not just the air it is not magnetism but is instead the mysterious Time/Space adhesion technology used in traction drives.
-Its super-science so it allows hand waves
-it is known to be something that golden age civilizations can invent
-it is known to use energy to create movement via a form of reactionless drive

Thus the 'levitation' effect could be Traction based, with the air-jets providing bulk propulsion and steering, possibly Traction assisted. Throw in some white noise/counter sound generators to offset the sound and your good to go.

Is this material from Phase World?

no, mutants in orbit.
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