How did the AT AT's breach the shield

[Darth Yan]

In ESB the empire has to resort to a ground invasion to breach the shields....but if bolts couldn't get through how could they get through the shield? Havok made the argument they could have just had the star destroyer flatten the base if rogue one is to be believed.

[Crazedwraith]

The usual explanation is that you have to be in ground contact to walk through the shield. Hence the walker design.

So no you couldn't just land a Star Destroyer there.

[Q99]

I've seen it posited that the shield is umbrella shaped. You can land stuff outside the edge and go in, but you start out a fair distance from the target.

Bombardment would work, but it'd require brute-forcing it giving the rebels more time to evacuate.

[Eternal_Freedom]

Bombardment is of questionable use - General Veers states the shield is strong enough "to deflect any bombardment." Since their force contains multiple ISD's and the freaking Executor that's saying something.

Plus, I may be remembering it wrong, but Vader's whole purpose was to raid and capture the base and the Rebels, not simply annihilating them.

[The Romulan Republic]

Yup. Wholesale orbital bombardment would likely pose a higher risk of killing Luke, when Vader wanted him alive.

[Vance]

What is Havok's argument? Land an ISD directly onto the shield?

I got the impression that they simply walked through the shield like the droids on Naboo or Thrawn's force in Zero Hour.

In the case of ground based shields (and seemingly Endor / Scarif) planetary shields you must be grounded in order for this permeability to work; starfighters and hovertanks (and blaster bolts/projectiles...) still couldn't pass through. This contrasts with the space based shields with regards to the [hypothesised] semi permeable vulnerability against starfighters, which might allow fighters to bypass the shields to strike at hulls directly.

[Shroom Man 777]

Havok's being a moron as usual. I suspect he's actually trying to troll people who like Rogue One. Or maybe he's gone down the rabbit hole of nerds.

The ISD couldn't go too near because of the ion cannon... that was the whole reason why Vader strangled a captain for dropping out of hyperspace at the wrong time!

Whatever, ion cannon or not, the ISD couldn't bombard the shielded base whether it was near or far. The only way for the ISD to breach the shields would be if it landed OUTSIDE the shields and people went freaking Klaus Kinski and Werner Herzog by DRAGGING the ISD through the shields. Yes. AT-ATs acting as giant mules!

[Q99]

Who's this Havok? I don't know them and it seems an iffy argument.

[Gandalf]

I've seen it posited that the shield is umbrella shaped. You can land stuff outside the edge and go in, but you start out a fair distance from the target.

That's what I thought it was, because it explains why the Rebels have speeders that apparently can't go in and out of their own shields while the Empire can.

[Elheru Aran]

Who's this Havok? I don't know them and it seems an iffy argument.

Havok=poster from here who doesn't post much anymore, but is still active on FB; I presume Yan is familiar with him there.

Unless there's another Havok floating around.

[Vance]

I've seen it posited that the shield is umbrella shaped. You can land stuff outside the edge and go in, but you start out a fair distance from the target.

That's what I thought it was, because it explains why the Rebels have speeders that apparently can't go in and out of their own shields while the Empire can.

Well there was no reason for snowspeeders to leave the shield dome. It's possible you may just be able to take off and fly around within the shield whilst not being able to fly through the shield-perimeter walls. This offers the potential for massive air superiority to those under such a shield (and maybe necessitates the use of armoured walkers which might resist artillery and air strikes upon entering the shield).

On the much larger scale you couldn't fly through Scarif's shields from space or vice versa, but ships could still fly around in atmosphere beneath the shield.

[Vance]

I've seen it posited that the shield is umbrella shaped. You can land stuff outside the edge and go in, but you start out a fair distance from the target.

That's what I thought it was, because it explains why the Rebels have speeders that apparently can't go in and out of their own shields while the Empire can.

Well there was no reason for snowspeeders to leave the shield dome. It's possible you may just be able to take off and fly around within the shield despite not being able to fly through the shield-perimeter walls. This offers the potential for massive air superiority to those under such a shield (and maybe necessitates the use of armoured walkers which might resist artillery and air strikes upon entering the shield).

On the much larger scale you couldn't fly through Scarif's shields from space or vice versa, but ships could still fly around in atmosphere beneath the shield.

EDIT: I don't get it. If it was umbrella shaped and high enough that AT AT's could pass, then fighters could get in and out too just by flying low to the ground.

[Gandalf]

Havok's being a moron as usual. I suspect he's actually trying to troll people who like Rogue One. Or maybe he's gone down the rabbit hole of nerds.

The ISD couldn't go too near because of the ion cannon... that was the whole reason why Vader strangled a captain for dropping out of hyperspace at the wrong time!

Whatever, ion cannon or not, the ISD couldn't bombard the shielded base whether it was near or far. The only way for the ISD to breach the shields would be if it landed OUTSIDE the shields and people went freaking Klaus Kinski and Werner Herzog by DRAGGING the ISD through the shields. Yes. AT-ATs acting as giant mules!

If all they need is to be in contact with the ground, why not just drag some cabling, thus ensuring constant contact, and fly along the surface?

[Elheru Aran]

Havok's being a moron as usual. I suspect he's actually trying to troll people who like Rogue One. Or maybe he's gone down the rabbit hole of nerds.

The ISD couldn't go too near because of the ion cannon... that was the whole reason why Vader strangled a captain for dropping out of hyperspace at the wrong time!

Whatever, ion cannon or not, the ISD couldn't bombard the shielded base whether it was near or far. The only way for the ISD to breach the shields would be if it landed OUTSIDE the shields and people went freaking Klaus Kinski and Werner Herzog by DRAGGING the ISD through the shields. Yes. AT-ATs acting as giant mules!

If all they need is to be in contact with the ground, why not just drag some cabling, thus ensuring constant contact, and fly along the surface?

You know, maybe that explains the weird speeder/pod-racer things in that Last Jedi trailer...

[Khaat]

The presumption (supported by on-screen evidence) is that an object passing through the theater shield has to be grounded (like the battle droids in Ep I, or ATATs in Ep V). The TF tanks (AATs) couldn't gravitate through the shields because they (presumably) couldn't - they weren't grounded, being repulsorcraft.

"So why not carry a chain you could drop out the back to ground yourself?" Good question! Maybe shield interaction has something to do with repulsorlift generator properties, too.

The theater shields in Ep I & V (umbrella shields) reach out over an area, but touch the ground at their limits. A planetary shield (like Endor, or Alderaan, or Skarif) has to be breached either by massive power (Death Star), or opened under specific circumstances (the gate over Skarif), or technobabble (StarKiller Base).

Edit: I'll have to take another look at the Last Jedi trailer, now....

[Shroom Man 777]

Havok's being a moron as usual. I suspect he's actually trying to troll people who like Rogue One. Or maybe he's gone down the rabbit hole of nerds.

The ISD couldn't go too near because of the ion cannon... that was the whole reason why Vader strangled a captain for dropping out of hyperspace at the wrong time!

Whatever, ion cannon or not, the ISD couldn't bombard the shielded base whether it was near or far. The only way for the ISD to breach the shields would be if it landed OUTSIDE the shields and people went freaking Klaus Kinski and Werner Herzog by DRAGGING the ISD through the shields. Yes. AT-ATs acting as giant mules!

If all they need is to be in contact with the ground, why not just drag some cabling, thus ensuring constant contact, and fly along the surface?

As the previous poster said, repulsorlifts are probably messed up by the shield fields...

So the ISD must be landed, like it must be DRAGGED across the ground by AT-ATs, like mules dragging plows!

[Imperial528]

From an air combat perspective, going underneath a shield where you lack native air and ground superiority is a terrible idea.

If the ground based AA gets too hot, you have literally nowhere to go. You have no room to maneuver, and no ability to gain altitude. The enemy air forces are free to fly as low as they want or as high as they want, so long as they have ground emplacements any maneuvers you would use to attack them exposes you to ground fire.

Deploying TIEs during the battle of Hoth would have likely greatly increased losses without producing much benefit given the already present ground forces being perfectly capable of securing the objectives.

[Khaat]

Okay, until a line of dialog says otherwise, I think the repulsor flyers in the Last Jedi trailer throwing up plumes by dragging their penises .. fins are just for visual effect, like the X-wings throwing up rooster tails in TFA over the water at Takodana (Maz Kanata's).

[Q99]

From an air combat perspective, going underneath a shield where you lack native air and ground superiority is a terrible idea.

If the ground based AA gets too hot, you have literally nowhere to go. You have no room to maneuver, and no ability to gain altitude. The enemy air forces are free to fly as low as they want or as high as they want, so long as they have ground emplacements any maneuvers you would use to attack them exposes you to ground fire.

Deploying TIEs during the battle of Hoth would have likely greatly increased losses without producing much benefit given the already present ground forces being perfectly capable of securing the objectives.

Toss in that Hoth was apparently hell on fighters, there was dialog about the rebels having to snow-proof for operation there (the snowspeeders specifically took time to make ready for combat on Hoth). Sure, you can fly there, but frost on windows, snow, components overheating to compensate, etc. may be real hazards, especially if you have to fly down under a level not might higher than the height of an AT-AT.

You could end up with a turkey shoot where TIEs begin losing performance or even crashing not long into the fight, in addition to coming in from a tight predictable area

[Galvatron]

Should starfighters that can operate in the freezing vacuum of space be as vulnerable to the cold as atmospheric airspeeders are? I'm not an engineer so I'm truly asking in a non-rhetorical way.

[Imperial528]

It depends on the way the starfighter deals with heat.

If TIE fighters rely on liquid coolant to cool their systems, which would be a reasonable assumption given their large radiator wings, they may lose heat too quickly in a cold atmosphere (or indeed an atmosphere in general) and the cooling system could fail or perform sub-optimally.

[Khaat]

Should starfighters that can operate in the freezing vacuum of space be as vulnerable to the cold as atmospheric airspeeders are? I'm not an engineer so I'm truly asking in a non-rhetorical way.

(Also not an engineer, but I'll take a stab at it) Space is empty, so heat loss is only through only radiation (okay, maybe convection as well.) In an atmosphere, there is heat loss through radiation, convection, and conduction.

[Galvatron]

FWIW, TIEs seemed to work fine in the atmospheres of Scarif, Bespin, Jakku, Takodana and Starkiller Base.

[Khaat]

Well, from the other angle, the X-Wings and rebel transports seemed to do just fine, but they were only blasting their way off-planet, not running combat operations in-atmo.

So I guess there might be a question in "was whatever was wrong with the Falcon related to the cold?"

[Crazedwraith]

I always wonder if, aside from them just being more valuable as transport escorts. The starfighters might just be too good to use as fighters in that situation. You've got engines that can pitch you into orbit in a few seconds and you're going to commit them where going too fast or too high is going to fly them in an energy shield?

Limited speed and altitude of an airspeeder might actually be advantage.