Repulsor lifts- why not?

[Noble Ire]

Are there examples of foot soldiers walking through the shields? I think I remember in TPM the droid soldiers walked through the Gungan's shields but I was curious if we have examples of biological creatures walking through a shield as well. It has been a long time since I have seen TPM and maybe the Gungan soldiers were able to walk through the shield as well but I am not sure.

No Gungan passed through the theater shield. In fact, shielding has been shown to be very damaging to organic elements that touch it (a person wearing a personal shield genrator can cut unarmored attackers in half with it.)

[Civil War Man]

I admit i have no idea how much the weight or subsequent penalty would be but: why should they be retractable? It doesn't need to maintain a certain height above the ground all the time, it can just lower itself onto fixed wheels/tracks (legs would be rather silly).

If they don't make them retractable, then they need to maintain a minimum height to keep from continually bumping their wheels/legs on the ground. It would ride as smoothly as a landing 747 otherwise. And also, I repeat, it's simpler just to give them the wheels/legs as their primary locomotion as opposed to a weird hybrid with each mode only being able to be used under certain conditions.

They had to create a whole new range of combat vehicles to be all-terrain yet shield-penetrating anyway: walkers. And why shouldn't such a 'breaching sled' be armoured too?

The difference is that the walkers were made to be combat vehicles as well as penetrate theatre shields. If you arm and armor the shield breaching units enough to make sure they are not vulnerable to attack, you just defeated the purpose of the repulsorcraft they are designed to carry, because now you have a shield-breaching combat vehicle.

I wasn't thinking of an exposed add-on, this component would make sense to be retractable. It only needs to be out for a few seconds while the boundary is being passed. Anything's benefits can be negated by it being damaged, and losing legs is worse than not being able to get back out past the shield.

A retractable grounder causes the same problem as the first part: they take up space that could otherwise be used for weapons/troops. And also there's the problem of the grounder being damaged while the vehicle is passing through the shield.

Since the idea with legs is that they're all-terrain, if it was fine for wheels then using repulsorcraft isn't an issue. But then repulsors are far better at 'all-terrain-ness' than legs, and apparently less complicated/vulnerable/etc.

Except in areas that disrupt repulsorlifts (such as the aforementioned theatre shield barrier or planets with unusual magnetic fields). I wouldn't be surprised if repulsorcraft are also vulnerable to EMPs. The AT-TE is shielded against such an attack (probably also it's descendent, the AT-AT), but it may be that applying the same benefit to a speeder would make the thing completely nonfunctional.

On a side-note, the AT-AT in its troop compliment can carry repulsorcraft like speeder bikes or Chariot LAVs, IIRC.

[Winston Blake]

I admit i have no idea how much the weight or subsequent penalty would be but: why should they be retractable? It doesn't need to maintain a certain height above the ground all the time, it can just lower itself onto fixed wheels/tracks (legs would be rather silly).

If they don't make them retractable, then they need to maintain a minimum height to keep from continually bumping their wheels/legs on the ground. It would ride as smoothly as a landing 747 otherwise. And also, I repeat, it's simpler just to give them the wheels/legs as their primary locomotion as opposed to a weird hybrid with each mode only being able to be used under certain conditions.

They need to maintain a minimum height anyway no matter what they've got attached (and this is assuming the wheels (not legs obviously) are attached to the bottom of the vehicle). Wheels, legs and tracks are all far inferior in rough terrain to a craft which can actually hover above the ground. The only conditions that they are inferior under is the tiny region of a shield boundary. Bolting four wheels onto an existing repulsor-AFV to support it's weight and move it across a shield boundary is obviously simpler than designing an entire range of walking vehicles that rely on legs which can't move over nearly as much or as rough ground and can be tripped, etc.

They had to create a whole new range of combat vehicles to be all-terrain yet shield-penetrating anyway: walkers. And why shouldn't such a 'breaching sled' be armoured too?

The difference is that the walkers were made to be combat vehicles as well as penetrate theatre shields. If you arm and armor the shield breaching units enough to make sure they are not vulnerable to attack, you just defeated the purpose of the repulsorcraft they are designed to carry, because now you have a shield-breaching combat vehicle.

Did i say armed? Or invulnerable? Such a sled only has to be resilient enough to survive pushing the combat vehicle a few metres through the shield until it can lift off and attack things, not a full-fledged AFV in itself. Hell, the combat vehicle could start firing on targets the moment it's cannon tips pass the shield.

I wasn't thinking of an exposed add-on, this component would make sense to be retractable. It only needs to be out for a few seconds while the boundary is being passed. Anything's benefits can be negated by it being damaged, and losing legs is worse than not being able to get back out past the shield.

A retractable grounder causes the same problem as the first part: they take up space that could otherwise be used for weapons/troops. And also there's the problem of the grounder being damaged while the vehicle is passing through the shield.

How big are you envisioning these grounders to be? Folded/rolled/etc up i'm seeing such a thing as taking up about one person's volume. I don't think they'd be that big a tradeoff, compared to developing walkers instead. The machinery to move an AT-AT's legs takes up far more volume.

I think this is another 'envisioning' problem. I see a grounder sticking out the back of the vehicle and being whipped up once it's through. Aren't legs a little more exposed? How does the enemy get up close under or beside it in order to take potshots at the grounder, while under fire from the vehicle? They might as well try to put shots down the barrels of its guns.

Since the idea with legs is that they're all-terrain, if it was fine for wheels then using repulsorcraft isn't an issue. But then repulsors are far better at 'all-terrain-ness' than legs, and apparently less complicated/vulnerable/etc.

Except in areas that disrupt repulsorlifts (such as the aforementioned theatre shield barrier or planets with unusual magnetic fields). I wouldn't be surprised if repulsorcraft are also vulnerable to EMPs. The AT-TE is shielded against such an attack (probably also it's descendent, the AT-AT), but it may be that applying the same benefit to a speeder would make the thing completely nonfunctional.

As i said directly after that, "I think this can be rationalised by simply saying we have no idea exactly what subtle weaknesses are fundamental to repulsors". I hadn't heard of repulsors being disrupted by unusual magnetic fields, so in whatever book this happened it gives us a perfect rationalisation as to why walkers are used instead (i mentioned the possibility of anti-repulsor force-field weapons earlier too).

[The Original Nex]

Are there examples of foot soldiers walking through the shields? I think I remember in TPM the droid soldiers walked through the Gungan's shields but I was curious if we have examples of biological creatures walking through a shield as well. It has been a long time since I have seen TPM and maybe the Gungan soldiers were able to walk through the shield as well but I am not sure.

Clone Trooper (and be extension Stormtrooper) armor allows them to walk through shields according to AotC ICS, without the protective armor, they would fry.

[Tanizaki]

Repulsorcraft, missiles, bomb, energy beams, and starfighters cannot enter through such a shield, but foot soldiers, wheeled or tracked vehicles, and walkers can.

I appreciated that a clear force field blocked visible energy beams.

[NRS Guardian]

There are other disadvantages to Repulsorcraft besides not being able to enter shields or work in funky magentic fields. Most seem to be more power intensive and less well armored. Also, walkers and repulsorcraft each have their own advantages and disadvantages that a military will try to take advantage of by having a balanced force. Just as modern militaries don't just have helicopters, or just have tanks.

[Darwin]

Are there examples of foot soldiers walking through the shields? I think I remember in TPM the droid soldiers walked through the Gungan's shields but I was curious if we have examples of biological creatures walking through a shield as well. It has been a long time since I have seen TPM and maybe the Gungan soldiers were able to walk through the shield as well but I am not sure.

Clone Trooper (and be extension Stormtrooper) armor allows them to walk through shields according to AotC ICS, without the protective armor, they would fry.

Apparently the event horizon of an active shield causes pretty severe heat effects on anyone touching it. Thus why Clone/Stormtroopers need full body armor to pass through.

[MindTwist]

Was the shield for the underwater gungan city the same type of shield as used in the battle? If so, Jar Jar and the Jedi passed through it. Although it could have been a special low intensity section or something.

[Pcm979]

Well, the most logical assumption to make about why they don't just dangle a chain/walk alongside the craft is because it wouldn't work. This is pure speculation, but maybe the energy has to be grounded through an object of proportionate size to the vehicle passing through the shield? Also, maybe the vehicle has to be a certain distance off the ground, making walkers neccesary?

As to all the loopholes to get the vehicle through, lets take a look:

Vehicle has both conventional and repulsorlift methods of locomotion: Redundant. If you have a vehicle that can get around conventionally what's the point of adding repulsorlifts? It'd only add to the cost.

Vehicle is towed though: Now you've got a vehicle that is capable of handling the weight of the repulsorcraft and, since this is a war zone, presumably just as well armoured. Congratulations, you've just doubled the cost of your war machine and halved the storage space.

Also bear in mind that you can't just slap wheels on something and roll it through the shield, you need suspension, gearboxes, a seperate engine to the 'lift... It's just a massive waste of resourses.

[Dangermouse]

Well, the most logical assumption to make about why they don't just dangle a chain/walk alongside the craft is because it wouldn't work. This is pure speculation, but maybe the energy has to be grounded through an object of proportionate size to the vehicle passing through the shield?

Maybe. Lets look at examples of vehicles/droids that have passed through shields. First, the Imperial Walker.

We can very crudely estimate the surface area of a walker's footpad and the walker itself:



I estimate 37 m^2 for the wide side of each leg, 181 m^2 for one side of the body, and 80 m^2 for the top/bottom. The other side of the leg looks to be half of the wide side. So the walker has an approximate surface area of 960 m^2.

For the footpad, the diameter is approximately 4.75m for a surface area of 17m^2. For three pads in contact with the ground, the grounding area is 53m^2.

For the Imperial Walker, the pad's surface area is 5% of the walker's surface area.

Now, the droid:



The droid's leg has an approximate surface area of 0.31m^2. The body has an approximate surface area of 0.57m. The total surface area of the droid (neglecting the head and arms) is then 1.2 m^2. The footpad of the droid has a surface area of approximately 0.01m^2 (0.19m x 0.05m).

For the droid, the foot pad's surface area is 0.8% of the droid's surface area.

If we are assuming that grounding allows the vehicle to pass through the shield, it doesn't seem that the contact area of the grounder needs to be of a significant size as compared to total surface area of the vehicle,

Also, maybe the vehicle has to be a certain distance off the ground, making walkers neccesary?

This might be true. The main body of the walker is fairly high off the ground; this is less true for the droid. <Shrugs>

[Pcm979]

This might be true. The main body of the walker is fairly high off the ground; this is less true for the droid. <Shrugs>

I was thinking that the needed height off the ground might also be proportionate. I am, however, pulling all this from my arse.

[Winston Blake]

There are other disadvantages to Repulsorcraft besides not being able to enter shields or work in funky magentic fields. Most seem to be more power intensive and less well armored.

I'm not really pushing the point any more, but just regarding power use, i was under the impression that repulsors hardly use any power at all, e.g. Luke's speeder being left 'on' constantly. Actually now i've got the Ep2 ICS in front of me, it says "Gravity-altering devices include repulsorlifts that allow unpowered antigravity floatation".

Also, walkers and repulsorcraft each have their own advantages and disadvantages that a military will try to take advantage of by having a balanced force. Just as modern militaries don't just have helicopters, or just have tanks.

True, but what i was trying to say was like it's not as if modern militaries are going to start building mecha or something just for the sake of greater variety, when existing vehicles already do (more efficiently) any job they could do (except for a few tiny advantages).

[Winston Blake]

As to all the loopholes to get the vehicle through, lets take a look:

Vehicle has both conventional and repulsorlift methods of locomotion: Redundant. If you have a vehicle that can get around conventionally what's the point of adding repulsorlifts? It'd only add to the cost.

As i said above, i'm not arguing the point any more since repulsors have been established to be vulnerable to easily replicated environmental conditions. Still, my view was that the equipment needed for a 'once or twice per mission', 'few second' trundle isn't going to need anywhere near the capabilties and robustness of a complete, normal locomotion system. I wasn't talking about a true hybrid vehicle, more like a repulsorcraft with a major upgrade. As for cost, this all has to be compared to designing and building an entire new range of legged vehicles.

Vehicle is towed though: Now you've got a vehicle that is capable of handling the weight of the repulsorcraft and, since this is a war zone, presumably just as well armoured. Congratulations, you've just doubled the cost of your war machine and halved the storage space.

I don't think a basic single-vehicle trailer would cost as much as an entire new M1 tank, for example. There'd also be no reason why they couldn't have several repulsorcraft per 'sled'. Don't forget when you think about storage space that lines of shiny new AT-TE's, AT-AT's, AT-ST's, etc take up space too.

Also bear in mind that you can't just slap wheels on something and roll it through the shield, you need suspension, gearboxes, a seperate engine to the 'lift... It's just a massive waste of resourses.

True, you do need those things, which i think SW tech could handle easily. As i said above, this all has to be compared to designing and building an entire new range of legged vehicles. I mean, mechs would need feet, shock absorbers, knee joints, hip joints, leg sections, an engine, and the most nightmarish 'gearbox' ever conceived by a sapient mind, as well as designing/testing/implementing all that stuff.

Anyway, this is all still assuming repulsorcraft don't have intrinsic exploitable weaknesses, which we know they do from Civil War Man.

[Oskuro]

My thoughts on this issue:

-Firstly, we are assuming that the Gungan shield operates in exactly the very same manner than the Echo Base shield. I'd like to point out that the Echo Base shield was designed to withstand orbital bombardement from Star Destroyers, and was apparently fed by more powerful generators. Then again, both shields could be similar, but if we assume the Echo Base shield as being stronger, we could rationalize that the use of heavily fortified AT-ATs was mandatory in order to actually penetrate the shield. Maybe lesser vehicles did not have the armor or the power to walk through it (Droids in TPM had to defeat a certain resistance when moving through the Gungan shield, so maybe mor powerful shields require greater pushing power, and matching armor to take the structural stress of pushing through).

-Secondly, maybe the very nature of repulsorlift engines has some effect here. Maybe intersection with the force field causes some kind of damage or undesirable effect to repulsorcraft. Of course, since we ignore the inner workings of repulsor-lifts, we can't say much about it.

-Thirdly, considering the relative urgency of the attack (Given that the fleet emerged from hyperspace too close to the system), maybe there wasn't much time to tune the different repulsor craft to operate in the harsh conditions (remember that the rebels had trouble adapting their speeders, and they already knew they were going to Hoth, so had time to prepare). If this was the case, it seems logical that the commander chose to deploy infantry-loaded ATATs as soon as possible, rather than lose time with any preparations.


Also, it is worthy of note that, in TPM, the Droid army did not advance their tanks to try and get them through the shields, but deployed their droids. And those tanks flew low enough for them to go skidding on the ground if it was a matter of grounding... Although not wanting to lose a vehicle to catapult fire when crossing the shield might be a valid reason for the use of less expensive droids.

[LeftWingExtremist]

From what I hear repulser vehicles are also supposed to be easily detected by sensors, but this is only form memory.

[darth korte]

Was the shield for the underwater gungan city the same type of shield as used in the battle? If so, Jar Jar and the Jedi passed through it. Although it could have been a special low intensity section or something.

gungan shield in their underwater cities and submarines are (if i remember correctly) electro static field. it "only" stops water flooding in and let solid objects pass through it