Grav vehicle telltale

[Icosahedron]

Are there any sounds or sensations when a grav vehicle is in the vicinity?
What noise do they make?
Would you sense anything if one flew over you, hair standing on end, stomach lurch, etc?
Any suggestions?

 

[Rover]

I do not recall anything canon on this.

Considering this do not exist in the real world I think you are free to impose any effect you want, be it sound, visual or viseral.

Personally I would consider these to be solid state and the gravatic effect only detectable with equipment capable of detecting electrical or gravetical (?)fields.

R

 

[Lord Kalvan of Otherwhen]

You mean they don't sound like George Jetson's car???

 

[Andrew Boulton]

A low hum, rising to a whine if you push the thrusters too hard.

I don't think they can have much, if any, effect on things they pass over, otherwise they'd be too dangerous.

 

[sgbrown]

How about a slight tweaking of the inner ear leading to momentary inbalance if witin an "affected" zone of a few meters?

 

[far-trader]

I've always been fond of the crushing overrun with a grav tank

And too I like pressure triggered anti-tank mines to counter such tactics. So I figure there is some ground pressure effect.

However, as it's the weight spread over the whole area of the lifter surface with an inverse square applied for elevation the actual pressure is negligible for something like an Air/Raft or Speeder at minimal ground clearance. Getting "run over" by a light grav vehicle won't hurt though it might knock the wind out of you. And even the heavier grav craft cause little disturbance at NOE altitude. It's only really heavy craft at low elevations (like grav tanks rolling low over the ground or spacecraft taxiing and in low approach) that can cause problems.

As for sound I take about the same view as Andrew, inaudible (or below human hearing range) for low power applications like grav-belts, a low rumbly hum for light vehicles at moderate speed or idling heavy craft, building to a whine as the power level increases.

 

[mbrinkhues]

Depends on the Traveller version you use. In most they will be silent except for the airflow noises at higher speeds.

In TNE they will sound like a jet due to the seperate and fuel-using thrusters. If they use a non-nuclear power source like an MHD turbine as they do in some TU outside TNE, the engine might be audible too.

On the "ground pressure" thing I always assumed that there was a "grav triggered" mine set to a certain field strength. Using the MT explanation of Grav plates the craft has no effect on the ground but the field can be measured/detected.

 

[far-trader]

Well I'm of two trains of thought leading to there being some sound, at least in many cases.

One is the amount of power being used in a direct energy to field conversion just seems like it's going to create a sound much like a high voltage transformer. But then we don't really know since it's fiction. It could be silent, it could be a hum, it could sound like running water, or wind chimes. OK, maybe not so the likely the last two.

The other is ergonomic. Even if you can make it silent, in many cases you'll want some noise associated with the correct functioning and state of power draw for another positive feedback of operation to the operator and others. This would be especially important in crowded shirt-sleeve urban settings and for manually operated open craft, like the ubiquitous Air/Raft. You may have noticed in real life some vehicles even have sound added in some situations.

Of course it's less important for other operations. And not desirable for military operations requiring stealth. But let's face it, grav tanks are not really a stealth platform.

Actually I had an experience just this afternoon that drives (no pun intended) the point home. I pulled in to nose parking downtown and the car next to me pulled out after I stopped, almost silently. I was 2 feet from it and had to strain to hear the engine. If I'd gotten out and walked across the street it could have backed right over me without me hearing it. There are times when a properly moderated sound is a benefit.

Another example from past experiences. A driver who couldn't hear that their car was in serious trouble because of the stereo being turned up too high. The same effect as if the engine were silent even when not operating correctly, leading to serious damage and failure. Not a big problem when you're driving around town on the ground, HUGE problem if that drive involves flying at altitude in an Air/Raft with the glide ratio of a brick. Flying along in your silent Air/Raft when suddenly the engine starts to cut out and goes through silent sputters really doesn't tell you to get down in a hurry. Oh, your instruments are going to tell you there's a problem? They didn't alert the driver of the car in the example above, the instruments were working fine but the driver wasn't looking.

So most grav makes some noise in my TU. The exceptions are just that, and usually due to dampening fields.

I think a grav triggered mine would be too easy to spoof/disarm remotely rendering it useless for area denial. It'd also probably be a pretty expensive bit of technology making it even less justifiable. And requiring a power source may lead to a more detectable signature for another minus. All just my opinion of course.

I don't recall the MT explanation re grav ground effects off-hand, or where I came up with mine or even what specific justifications I had, if any. I really just prefer it and the sound ideas for the cinematics

 

[Jame]

I have been thinking that at the TL of introduction, a Grav Vehicle will make quite a bit of noise, like at least a truck. However, it gets softer as TL improves (a TL-12 grav vehicle makes a moderate-low hum), but never entirely goes away.

The heavier the vehicle, the more noticeable sound. For example, an air/raft will make the least sound, while a grav "eighteen wheeler" or a tank will make the most.

 

[Commander Drax]

I think it was mentined in several MegaTraveller sources that grav plates/modules make a slight humming noise, though not loud enough to be a problem. Also grav vehicles react poorly to cold surface conditions - I think this was in some of the DGP stuff for MT although this may soon be something of a moot point if DGP stuff gets de-canonised!

Anyway - Gravitic Displacement - an alternative lifter technology described in FFS1 operates by spreading the weight of the vehicle over a larger surface area, as described by Far-Trader, thus a grav tank mounting a crushing over-run would be an effective weapon against ground troops at low altitudes (literally 1 or 2 meters). However a gravity triggered mine would be a brilliant defence against this form of attack, which leads me to think that a lovely high tech star ship in orbit with a long range repulsor aimed at the battle field, it could trigger all of the grav mines clearing them ahead of the arrival of allied forces and possibly doing damage to any native defenders.

Also could a sufficiently powerful repulsor be used to demolish field fortifications, buildings and other important structures if applied in Low Orbit.

 

[mbrinkhues]

Originally posted by far-trader:
cut a lot...


I don't recall the MT explanation re grav ground effects off-hand, or where I came up with mine or even what specific justifications I had, if any. I really just prefer it and the sound ideas for the cinematics

A cinematics. Now you should have told me that THOSE evil critters are the reason your vehicle sounds that way. Cinematics are something even the best engineer can't get rid of. Just ask Income, Sinar Fleet Systems or Utopia Planetia Yards

Granted, for dramatic reasons Grav vehicles should generate a certain sound effect to convey their weight/power/danger. Starting with a low frequency rumbling that is more felt and ending with a thundering rush when that Intrepid G-Tank finally passes you.

 

[Fritz_Brown]

Ummm, the weight of the vehicle shouldn't make a difference, folks. Everything is volume-based, remember?
Oh yeah, agree with FT about cinematics. Whole-heartedly.

 

[Icosahedron]

I found a single post in a similar vein on the 'evolution of a starport' thread. To carry it here, I'm querying whether the '1G overpressure' under a grav tank would actually crush a trooper under several hundred tons of tank weight, or whether the 'extra 1G' would simply double his own weight. Bear in mind that G-vehicles do not apply a thrust against the surface or the air to stay aloft like conventional craft, but react against the planetary G-field in some (handwavium) way. Perhaps the trooper underneath would only feel the G-force applicable to a 100ton mass - utterly negligible. What is the most likely nature of G-vehicle backwash? Using the '1G overpressure' idea, a vehicle could still possibly crush something on the ground by performing a 4G popup over it?
I like the idea of a low hum or whine from the G-generator, plus whatever sound the power plant may make.

 

[Icosahedron]

Repulsors as short range weapons! I hadn't thought of that one. I'd long-since reversed the polarity to provide a tractor beam, but... Hmm.

They'd be limited to the M-Drive thrust, otherwise the effect would simply push the ship away, but adding a mere 1G would convert most buildings to rubble, even if applied vertically.
It could pretty effectively suppress infantry, too; picture the 100kg encumbrance!

Tell me more.

 

[Valarian]

I like to think of grav modules directly exerting a pressure on the ground at low altitude. This is my take on gravitic modules (and the more powerful Gravitic Maneuvering Drive).

From the Evolution of a Starport thread:
</font><blockquote>quote:</font><hr />Newtons Third Law: All forces occur in pairs, and these two forces are equal in magnitude and opposite in direction.

When a ship is taking off or landing, the gravity modules/drive (to adhere to this rule) must exhert a pressure equal to the effort of lifting or slowing the ship on the planet. When the ship is in the air, this pressure will be extremely generalised and act on the planetary gravity as a whole. When the ship is close the the ground, this effect will be localised. When the ship is really close to the ground the whole effect will be centred on a small area (the footprint of the ship itself). If someone were to stand directly under the ship when it's taking off, the pressure exerted on the patch of ground they're standing on would be roughly equivalent to the person trying to lift the ship themselves.

The actual forces involved would depend on the weight of the ship, the acceleration of the ship (number of G's), and the ratio of the footprint of the person's body to the footprint of the ship as a whole. Someone more mathematically minded could probably come up with the formula.</font>[/QUOTE]To apply this thinking to a vehicle, a G-Carrier trundling a metre from the ground would exert a force on the ground as it moved. When stationary, the force exerted will be directly under the G-Carrier and equal to the force required to keep it's weight a metre in the air. When in motion, the force would be slightly behind the G-Carrier as vectors come in to play. The force would be equal to that required to accellerate the mass of the G-Carrier to the required speed, and still keep it a metre in the air.

At altitude the effect of the force on the ground below is more generalised as the forces are spread over a wider area. At high altitude, the gravitional forces being manipulated are those of the planet itself and the pressure on any particular area of the planetary surface is negligable.

Oh ... and grav modules Thrum. When idling, this is a quiet, slow Thrum in the background. It gets louder and quicker as more demand is made of it. If the grav module is taxed, then this becomes a pained continous Thrum.

[EDIT]
Also see this thread.
[EDIT ENDS]

 

[kaladorn]

In Striker (the original), I think you didn't do any ground pressure calcs for grav, suggesting no ground pressure at all. If you had ground pressure for grav tanks built with the various aligned superdense or crystalliron hulls and high armour values, you'd probably crush streets and sink into bogs and swamps just like conventional tanks. Not sure that would make any sense.

As to repulsors: If a ship can hit my infantry and ground installations, my ground installations (with generally bigger power sources) can hit the ship. Most ships won't like a few extra Gs applied in odd directions either. This sort of weapon becomes generally destructive, which is why I can't see it being workable. Imagine what it would to to missiles - it would make a great point defence. It could be used to spin starships like a top (induce unexpected pitch, yaw or roll). And of course, if you combine tractor and repulsor (ah, Andromedans, how I don't miss thee...), you've got a weapon that could tear apart fighters, missiles, ships, people, facilities, etc.

As to the noise point: I think it is like anything else - cheap or heavy duty versions of the grav module will make noises in some relation to that. Expensive ones will be quieter. This seems true in just about any transport technology - luxury cars seem to be very quiet. Luxury grav vehicles will be no different (and military stealth tanks *are* a likely development).

Noise is engineered into cars for audible feedback (my Mustang has it so it sounds like a sportscar, but it lets me shift without looking at the tach). But it could fail with zero warning (cracked intake manifold, for instance... had this happen twice so far). I can se the same sort of failure (not specifically, same class of failure) in a grav module happening without warning.

So, flying vehicles must have some other fail-soft methodology. Is it the rocket-launched parachute? (modern ultralights have these as do some small planes and they're working on ones for jet liners). Is it an auxilliary one use grav module that just gives you enough juice one time to land under control? Is it a solidifying crash-foam spray inside the cockpit and to heck with anybody or anything you hit? Any and all of these in combination? Some sort of safety regime must reasonably be in place. Failures happen, even in the 3I. So engineers would have evolved fail-safe or fail-soft hardware and software.

 

[Icosahedron]

Valarian,
I feel that your explanation of the 'pressure' owes too much to conventional thrust mechanisms which have to react on air or ground very locally in order to provide the 'equal and opposite force'. A grav vehicle is reacting against the planet's centre of mass, and I see little difference between the effect at 6000km (surface distance) and 6010km (intercontinental flight altitude). In either case, I think the vehicle will be pushing against what amounts to the entire planetary diameter using calculus-summed vectors.

Picture your pressure-exerting vehicle over water (or sand). The local pressure would make a hole in the water, creating a significant bow wave and wake as the vehicle moved. Similarly, trails would be left in soft ground or snow (which could even be pressure-melted) and the uneven force applied to the rocks of a boulder field would have them rolling and skittering about all over the place as the vehicle passed, perhaps creating a significant 'friendly fire' hazard for nearby troops as pebbles are flicked out from under the vehicle with great force.

Does that feel like a grav-vehicle as we understand it?

Maybe the vehicle doesn't 'react against' gravity at all. Rather than attacking gravity by brute force, a grav module could somehow weaken the gravitational field between the module and the planet, in which case the trooper underneath might actually feel lighter than normal?

What other explanations could there be for anti-grav?

 

[TheEngineer]

Hi !

Beware, physical bullshit starts now:

Well, the easiest approach is perhaps to say, that anti-grav module technology turn a certain amount of matter to behave gravitationally reverse.
Physically, this would mean, that the known formula:
F=G*(m1*m2)/r²
is reduced to somehow constant surface conditions
F=m*(-g)
So far, the grav module would just be piece of matter, that behaves contrary as a regular mass.
Traveller Low Power g-modules provide a little more magic, as only 20 kg of g-module give 1000 kg of thrust

G-modules seems to be able to alter either the mass of their module core, or properties of the gravitational constant itself.
But this is perhaps still a topic for Imperial Research Stations.
But theres more magic: anti grav technology is not only able to reverse the direction of a natural gravitational source, its also able to alter the direction completely.
This leads to another interpretation:
G-modules are able to alter and modify the gravitational field or just space time curvature on a microscopic level.
In contrast to starships maneuver drives, which are able to put the whole ship into such a field, resulting in a volume dependent locomotion.

So, as typically described in the Traveller ruleset, a anti-grav module really is just a piece of matter, whose "gravitational" behaviour is widely controlable, resulting in a force, which could be used to move a mass.
Using that picture, IMHO there would be no notable effects around such a module (except some sound perhaps). Now, thats not completely correct, as there is indeed a tiny anti force pushing away from the module, just as any regular mass produces a pulling gravitational force.

Regards,

TE

 

[Straybow]

If gravity is a distortion of space then gravtech is a manipulation of the shape of the surrounding space. This manipulation decouples the enclosed mass from the nearby planet while maintaining a comfortable gradient within the field.

At the boundary of the volume there would be a gradual fading of the effect. Passing through this discontinuity causes the human semi-circular canals to lose their centering, i.e., mild vertigo.