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Repulsorlifts on Water?
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Yasriia
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PostPosted: Wed Jan 18, 2012 5:55 am    Post subject: Repulsorlifts on Water? Reply with quote

Okay, the more I read through wookiepedia, the more I have the feeling it was all a hallucination. I thought, that I've read somewhere, that repulsorlifts (in vehicles, droids, whereever) doesn't work on water. But right now, I can't find a single clue about it. Maybe someone here has heard about it.

So, here's my question: do repulsorlifts work on water?
If they do, why are there special water-repulsorlifts (not the design)?
If not, at what depth do they stop working and how does this failure look like (do they simply sink)?
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Matthias777
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PostPosted: Wed Jan 18, 2012 9:13 am    Post subject: Re: Repulsorlifts on Water? Reply with quote

Yasriia wrote:
Okay, the more I read through wookiepedia, the more I have the feeling it was all a hallucination. I thought, that I've read somewhere, that repulsorlifts (in vehicles, droids, whereever) doesn't work on water. But right now, I can't find a single clue about it. Maybe someone here has heard about it.

So, here's my question: do repulsorlifts work on water?

I can't recall any reference saying that they don't work on water, but I could be forgetting something. I know hoverboards from Back to the Future don't work on water, though... Wink

Yasriia wrote:
If they do, why are there special water-repulsorlifts (not the design)?

Which special water-repulsorlifts are you referring to?
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S-Foil
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PostPosted: Wed Jan 18, 2012 4:39 pm    Post subject: Re: Repulsorlifts on Water? Reply with quote

Matthias777 wrote:
I know hoverboards from Back to the Future don't work on water, though... Wink


McFly you bojo! Hoverboards don't work on water UNLESS YOU HAVE POWER!

As for repulsorlifts, I don't see any reason why they wouldn't work on water. I remember them described as anti-gravity devices, not anti-ground devices. If they somehow didn't work over water airspeeders could not function nor could the repulsors on a starship, as soon as one passed over a body of water it would drop like a stone and that would be no fun. Repulsors would be useless on Bespin, a place where we see an entire city kept aloft with them.
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Matthias777
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PostPosted: Wed Jan 18, 2012 6:50 pm    Post subject: Reply with quote

Actually, they are anti-ground devices. When you go off a cliff on repulsors only, you drop. Airspeeders don't have this problem (they use ion engines in conjunction with repulsorlift drives, generally), but landspeeders do (repulsorlift drives only). If you use your repulsors while in space, you can "kick" smaller objects (small asteroids, for example) away from you. One example I can recall off the top of my head is that Han Solo and Rogue Squadron used this tactic in an asteroid field against enemy TIEs.

I think that a body of water provides enough resistance to not part like the Red Sea, though. Re-reading the original question, I think the poster may have meant to ask if submersible vehicles can utilize repulsor technology IN water (beneath the surface), since he asked at what depth they would stop working. For the reasons above, and the fact that any submersible vehicles I can recall utilized other methods of propulsion, I would say that repulsors would not work underwater.
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Bren
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PostPosted: Wed Jan 18, 2012 7:08 pm    Post subject: Reply with quote

Matthias777 wrote:
Re-reading the original question, I think the poster may have meant to ask if submersible vehicles can utilize repulsor technology IN water (beneath the surface), since he asked at what depth they would stop working.
I read the OP as asking at what point would a repulsorlift vehicle be underwater even if it wasn't intended to be a submersible. Wink In other words, he/she was asking if - for example - a speeder with a ceiling of 3m would sink (and be wrecked) in more than 3m of water say when trying to cross a 10m deep lake.

OP, please clarify what your question was.

I'm not sure what the rules intend. I know in our games, we have allowed speeder bikes to travel above the surface of the water. Now I am wondering if that was really a correct interpretation - and by wondering I mean I am thinking that was an incorrect interpretation and that the ceiling for repulsorcraft would limit the depth of water that they could safely cross.

When looking through the adventure - Battle for the Golden Sun I note the following.
1) On page 8 - "You see five seatroopers on waveskimmers - small, one-man repulsorcraft - swirling around a rock outcropping that juts into the sea."

2) On page 22 in the description of the players' ship Explorer that the vehicle can operate "in planetary atmospheres or liquid environments using repulsorlift engines."

3) Page 33 "The Swimmer is a formidable weapon of war - the underwater equivalent of the AT-AT Walker. The Swimmer propels itself via massive repulsorlift engines.

From this it sounds like repulsorlift engines work on or underwater.

I don't read this as definitively arguing that water acts just like land. It is posible to read the descriptions as being consistent with an assumption that a vessel would need engines that are sufficiently powerful to reach the ground beneath the water - treating water as similar to air as far as a requiring a ceiling for repulsor craft. So normal civialian speeders designed to operate on dry land may not have sufficient altitude/ceiling to cross deep bodies of water. That is the interpretation I am currently leaning towards.

Thoughts?


Last edited by Bren on Wed Jan 18, 2012 7:29 pm; edited 1 time in total
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Fallon Kell
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PostPosted: Wed Jan 18, 2012 7:16 pm    Post subject: Reply with quote

I think it may have to do with bouyancy. A wide repulsor field could displace enough water to keep a heavy vehicle afloat where a narrow repulsor field with a heavy vehicle on top might sink through. This could be why special repulsor vehicles are built for water use.

Or it could just be that if a land repulsor vehicle breaks down over water, the occupants will be in serious trouble.
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Esoomian
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PostPosted: Wed Jan 18, 2012 7:30 pm    Post subject: Reply with quote

As far as I understand a repulsorlift vehicle reverses the local gravity but only to a degree and that is what gives it the flight ceiling however the problem with that interpretation is that a vehicle with a three metre flight ceiling would be unable to traverse a bridge that was more than three metres tall.

Probably best to assume they're anti-ground but based around anti-gravity so they won't function well without gravity.
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Bren
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PostPosted: Wed Jan 18, 2012 8:41 pm    Post subject: Reply with quote

Esoomian wrote:
...a vehicle with a three metre flight ceiling would be unable to traverse a bridge that was more than three metres tall...
Good point. I hadn't thought of that. So maybe a repulsorlift somehow uses a gravity field's energy to generate a counteracting push, but it needs a solid surface - like the ground or a bridge - to push against. So the flight ceiling on a speeder tells you how far above the ground the repulsor is able to push. Thus determining the effective depth of water that can be crossed or the effective "ceiling" in air.

The AT-AT Swimmer text describes it as having large repulsorlift engines and a space ship has an effective "ceiling" that is greater than orbital distance (and thus can cross any depth of water).
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Raven Redstar
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PostPosted: Wed Jan 18, 2012 8:44 pm    Post subject: Reply with quote

I would think that the fact that water is more "solid" than air would allow for a repulsorlift engine to keep it in maybe 1.5x or 2x their normal flight ceiling over depth of water.
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Bren
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PostPosted: Wed Jan 18, 2012 9:09 pm    Post subject: Reply with quote

OK. I went back to the rulebook (2nd Edition R&E). Page 242 discusses Repulsorlift Technology.

Quote:
By producing antigravity repulsor fields, these drives allow exacting control and high speeds or incredible cargo hauling capacity...

Repulsorlift vehicles are also popular because they are not restricted to roads and other smooth pathways - a boon to frontier and poor planets that can't afford funding for highway construction. Almost all atmospheric vehicles, and a majority of "ground" vehicles in the Known Galaxy, rely upon repulsor technology; primitive wheeled, hover and hydrocarbon burning engines are normally found only on the most primitive worlds, or on planets where repulsorlift isn't feasible due to random gravity and radiation fluctuations…

Speeders normally have a flight ceiling of less than five meters, so they are dependent upon smooth, well-groomed surfaces for smooth flight, such as natural flats, calm water or roads.


Again, it is not clear why vehicles have a flight ceiling nor whether the flight ceiling effects how deep the “calm water” can be and still provide an appropriate surface. I can easily see an argument, based on the “calm water” statement, that water provides a sufficient surface for speeder travel. I can also see an argument based on flight ceiling that would limit the depth of the water to the flight ceiling (or possibly some multiple of the flight ceiling).

I am curious whether anyone can find a more definitive game rule explanation for repulsor technology.
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Matthias777
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PostPosted: Wed Jan 18, 2012 9:53 pm    Post subject: Reply with quote

Does anyone recall seeing the "anti-gravity" concept explained anywhere? I feel like I once read an explanation that likened it to the colloquial use of the word "laser", in that it didn't necessarily mean that it was a device that negated gravity, but rather was just one more method of counteracting the effects of gravity, and repulsorlifts literally "repulsed" (pushed away from) whatever the repulsor field came into contact with. It is maddening to not be able to recall a source. I want to say it was in a WEG-produced book, but it might have been the Technical Journal, or one of the Essential Guides. I can't remember. The Squib battering ram and the aforementioned use against speeder-sized asteroids in space shows this to be accurate, though; repulsor fields don't need gravity to push away from in order to function, and repulsor fields can be oriented in any direction. This makes the concept of underwater repulsorlift drives work, too; the repulsor field is not operating against gravity or keeping the submersible vessel off of the ocean floor, it's operating in place of a propeller or other drive mechanism.
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PostPosted: Wed Jan 18, 2012 9:55 pm    Post subject: Reply with quote

If you want to play repulsors as being like a hovercraft with some sort of bubble of anti-gravity replacing a plenum chamber that would allow them to push off of a surface whether that be water or solid ground.

That then brings up a questions of what happens to things underneath the repulsor field. Can you damage objects by running over them with a repulsorcraft? Does a road need to support a particular ground load in order for a repulsorlift vehicle to use it?

Airspeeders become problematic in this model. Coruscant has thousands of repulsorlift vehicles flying around at all times, are there points below them that are affected by their repulsorlift field? If someone flies over another craft is that one pushed down?

I think the best way to run repulsors is to decide on a rule (they do or don't work on water) and handwave away any and all attempts at explaining them. I think that works unless someone can find a very definitive explanation of how they work as presented in the films. Luke's landspeeder travels easily over rough desert terrain, the Millennium Falcon can hover gently over the landing pad at Cloud City and take off vertically from the landing pad at Mos Eisley, the Cloud Cars on Bespin can fly all over the place with impunity, and the Emperor's shuttle managed to land gently in the Death Star Hangar.
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Matthias777
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PostPosted: Wed Jan 18, 2012 10:00 pm    Post subject: Reply with quote

S-Foil wrote:
If you want to play repulsors as being like a hovercraft with some sort of bubble of anti-gravity replacing a plenum chamber that would allow them to push off of a surface whether that be water or solid ground.

That then brings up a questions of what happens to things underneath the repulsor field. Can you damage objects by running over them with a repulsorcraft? Does a road need to support a particular ground load in order for a repulsorlift vehicle to use it?

Airspeeders become problematic in this model. Coruscant has thousands of repulsorlift vehicles flying around at all times, are there points below them that are affected by their repulsorlift field? If someone flies over another craft is that one pushed down?

As has already been stated, airspeeders use ion drives in conjunction with repulsorlift drives.
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PostPosted: Wed Jan 18, 2012 11:08 pm    Post subject: Reply with quote

Matthias777 wrote:
Does anyone recall seeing the "anti-gravity" concept explained anywhere? I feel like I once read an explanation that likened it to the colloquial use of the word "laser", in that it didn't necessarily mean that it was a device that negated gravity, but rather was just one more method of counteracting the effects of gravity, and repulsorlifts literally "repulsed" (pushed away from) whatever the repulsor field came into contact with. It is maddening to not be able to recall a source. I want to say it was in a WEG-produced book, but it might have been the Technical Journal, or one of the Essential Guides. I can't remember. The Squib battering ram and the aforementioned use against speeder-sized asteroids in space shows this to be accurate, though; repulsor fields don't need gravity to push away from in order to function, and repulsor fields can be oriented in any direction. This makes the concept of underwater repulsorlift drives work, too; the repulsor field is not operating against gravity or keeping the submersible vessel off of the ocean floor, it's operating in place of a propeller or other drive mechanism.

I treat them that way, but it's because of rampant disregard for technical hand-waving if it's not up to snuff, not because I have some secret knowledge about repulsorlifts.

That said, the word repulsorlift implies that it pushes against the normal force of the matter beneath it to lift itself, rather than locally reversing gravity.
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PostPosted: Thu Jan 19, 2012 2:44 am    Post subject: Reply with quote

Matthias777 wrote:
As has already been stated, airspeeders use ion drives in conjunction with repulsorlift drives.


This doesn't explain how air speeders can work though. They don't have large enough aerodynamic surfaces nor do they travel fast enough to maintain aerodynamic flight (as shown in the movies). They also don't seem to travel fast enough for ballistic flight.

An airspeeder's ion engines might propel them forward but I really don't see them also providing lift. This discussion is why I like to just say "there's flying cars, they just work".
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