Avatar Force Sub: UNSC (Halo)

[Hawkwings]

Yes, but remember that they didn't have very much time between detecting the horde gathering and going out and trying to blow up the tree. Their backup plan may have involved clearing out more forest or similar military-oriented ventures.

[adam_grif]

I think a lot of people have seriously overestimated the tactical effectiveness of those fliers, based on their effectiveness in the highly favourable conditions where the on-screen battle took place. Yes, if they can attack from all directions while obscured by inoperable sensors, fog, and giant floating pieces of physical cover, then they can be surprisingly effective against high-tech helicopters. But take them away from that almost perfectly configured ambush environment, put them in open air against enemies with high-tech weapons and working sensors, and you have a slaughter on your hands.

Even being able to take out the helicopters was pretty suspect. The arrows weren't scratching the canopies on those things, but then the dive bombing apparently added enough speed to make it punch clean through the whole way and then spear through a human and come out behind them. This is questionable.

I can't find a source for it now, but I distinctly remember reading that the failed Comanche helicopter's canopy was built to be able to shrug of 12.7mm NATO rounds.

The whole end battle was full of plot induced super competence on the part of the Na'vi, especially the parts where they were docking with flying vehicles in mid flight and then the people on board just kind of standing there shocked while the Na'vi flung them around. And Jake landing on top of a vehicle in mid flight and dropping grenades into things. It's just standard Action Movie schlock that, while not explicitly impossible, is just highly implausible.

[open_sketchbook]

Of course, highly improbable is what heroes are made of.

As for the diving extra velocity thing, I don't think it's too much of a problem. That's extra velocity + perpendicular impact + not fighting gravity, and at a closer range to boot. Also, when we saw arrows bounce off copters, it was the big Dragon flying battleship thing, not the little techno-Cobras and space-Hueys.

[Darth Wong]

Which is why they expected the Na'vi to come riding in animals. But come on, Eywa was a complete wildcard - the Na'vi themselves were totally NOT expecting it either.

Those wild animal swarms certainly did not have Charlies plugged into their bio-USB ports. I did not see any VCs interfacing with those space dinosaurs and pterodactyl swarms that rescued the Na'vi.

They still could be considered potential danger. Attacks on RDA by wildlife happened before, and they knew it was certainly a kind of wildlife that is dangerous even to fully equipped and trained soldiers.

Who cares about Eywa? Anyone who doesn't have robust defenses in an environment with wildlife that can destroy light armoured vehicles or snatch a man and carry him away in the air to eat him has got to be an absolute blithering idiot. Right here on Earth, large herbivore herds can stampede, and flying creatures can spontaneously create devastating swarms. Even without central co-ordination, the megafauna of Pandora would have to be considered a serious potential threat warranting significant defenses unless the administrator is an idiot. The fact that we know the natives can train the megafauna for their purposes only makes this even more of an obvious threat.

[adam_grif]

It's not like RDA doesn't have the capability to build those kinds of defenses either. The impression I got from the movie and some of the fluff was that they have some kind of resources-go-in-weapons-come-out setup that they hauled with them from Earth.

[Shroom Man 777]

Because helicopters have pretty low maximum operating altitudes, ant they are generally not made for any serious air to air combat. That's why i have written a few posts before about lack of fighters. Aircraft that are designed for outspeeding, outmaneuver and flying higher than their aerial opponents.
Enemy air force = fighters highly recommended.
Helicopters are not supposed to be main anti air force.

The helicopters/gunships did pretty fine in annihilating the Na'vi "air force". Yeah, dedicated fighters might've not even been touched by those swarms of animals, but the RDA is a friggin' mining operation - not a military - so the lack of fighters, the lack of tanks, the lack of futuristic phased plasma phalanxes that could've fried half a city with this baby, is justifiable.

Except for the little part when Quarritch is told that there is a biological, planet sized supercomputer out there, which has the ecosystem as it's part.
And he just laughed off this critical piece of intel.

Yeah, he was kind of a dick. But he hated Ripley. So... yeah.

Who cares about Eywa? Anyone who doesn't have robust defenses in an environment with wildlife that can destroy light armoured vehicles or snatch a man and carry him away in the air to eat him has got to be an absolute blithering idiot. Right here on Earth, large herbivore herds can stampede, and flying creatures can spontaneously create devastating swarms. Even without central co-ordination, the megafauna of Pandora would have to be considered a serious potential threat warranting significant defenses unless the administrator is an idiot. The fact that we know the natives can train the megafauna for their purposes only makes this even more of an obvious threat.

The RDA forces, as seen, were sufficient to kill or defend against rogue megafauna or Na'vi-trained animals. The only reason the attack was successful was due to the surprise, the close proximity, the sheer numbers of the animals, and the terrain. As you said, if this happened in a savannah plain or a prairie flatland, those space rhinoes would've been dead before they got anywhere near the RDA forces - and Quarritch and his mercs would've ended up having a whole lot of steak for dinner, lunch and breakfast the next day.

[adam_grif]

The helicopters/gunships did pretty fine in annihilating the Na'vi "air force". Yeah, dedicated fighters might've not even been touched by those swarms of animals, but the RDA is a friggin' mining operation - not a military - so the lack of fighters, the lack of tanks, the lack of futuristic phased plasma phalanxes that could've fried half a city with this baby, is justifiable.

That's Independently Targeting Particle Beam Phalanx to you, buddy. And it's a puppy, not a baby.

For shame, Shroom Man. For shame.

[LaCroix]

These people have machinery which eats through jungle like it's not even there, and they only cleared a 30m wide strip of forest around their base in a potentially hostile zone which the base administrator referred to as being on the brink of war? That's retarded.

In any case, we know they have heavy-duty forest-clearing equipment. With a week to prepare, they could easily clear a damned kilometre-wide firing zone around their base, dig in, and slaughter any attackers with all of those gun emplacements.

You forget the main point. Their forest clearing equipment is currently near Home-tree, and took about three months to get there.

Also, their equipment took ~3 months to get through 100 km of jungle, clearing only a road. Let's say they made it 50 m wide from the movie impression and a economical standpoint (only do as much as needed).

Assume they had downtimes with that, and assume they move at 100% capabilities to clear the killzone, ignoring non-critical damage to the equipment. Estimate they took 50 days for that road. Or 2km a day.

One time around the base is about 12 km, so they would be able to increase the killzone to about 80-100 m in the estimated week. But only if they manage to get their bulldozers back to the base somehow.

As an afterthought - i don't know if they can even produce ammunition on-site. It's one thing to find iron ore and produce stuff, but chemical propellants? I think ammo would be the 'valuable cargo' that needed to be imported.

[adam_grif]

As an afterthought - i don't know if they can even produce ammunition on-site. It's one thing to find iron ore and produce stuff, but chemical propellants? I think ammo would be the 'valuable cargo' that needed to be imported.

It's not like you can grab a rock and build a helicopter with it either. It's far more complex than that, materially. Unless you're building simple furniture and solid shapes, you're going to be needing all sorts of different resources. Manufacturing ammunition on site doesn't really seem any less likely than manufacturing AMP suits.

[PeZook]

As an afterthought - i don't know if they can even produce ammunition on-site. It's one thing to find iron ore and produce stuff, but chemical propellants? I think ammo would be the 'valuable cargo' that needed to be imported.

It's not that difficult: it's all nitrates, and they have a crapload of raw materials for that right outside the base.

Basically, you can easily go coal -> ammonia -> nitric oxide -> nitrogen dioxide -> nitric acid -> nitrocellulose -> propellant

From there, it's a question of designing a production process that won't blow you up, but it's still way cheaper than shipping all explosives from Earth. Of course, making explosives on-site would probably be pretty slow, but then again, the interstellar ships can only carry 350 tons of cargo, so it's not like you can get them fast from Earth, either.

The casings are trivial with their fabricators.

And, of course, there's other ways to produce the necessary ingredients. Hell, with nitric and sulfuric acid and toluene you can even make TNT, as long as you can get the toluene from somewhere. I can imagine the most important department on the base is the people who spend their days thinking up solutions to problems like these, writing up the procedures and fiddling with the fabricators.

[LaCroix]

Even being able to take out the helicopters was pretty suspect. The arrows weren't scratching the canopies on those things, but then the dive bombing apparently added enough speed to make it punch clean through the whole way and then spear through a human and come out behind them. This is questionable.

I can't find a source for it now, but I distinctly remember reading that the failed Comanche helicopter's canopy was built to be able to shrug of 12.7mm NATO rounds.

You are confusing energy and momentum. there is a whole lot of whoop-ass stored in a six feet long piece of hardwood in movement.


A cal 12 bullet weights arount 40 grams with 900m/s -> 0.04*900 = 36 kg*m/s; so let's take that as benchmark

A normal 28" fir/cedar arrow weights about 30-40 grams. An war arrow would be made of oak or similar hardwood, and a different tip, easily doubling that weight(70-80 grams). It's 2,5 times longer -> 175-200

Also, the longer arrow would be much thicker to work with that bow (half to 3/4 inch diameter as in comparison to the 11/32 inch of a normal arrow) who seemed to achieve flight speeds of 150 ft/s or more. So you can assume those arrows weighting easily about 500 grams. That's no toy anymore!

The bow alone:
0.5 kg*50m/s= 25kg*m/s

This would obviously not penetrate, although scratches are quite possible

But in dive:
The banshee is said to reach dive speeds of ~140 knots - 260km/h -> 72 m/s; that's more than the arrow alone would achieve!

0.5*(50+72)= 61kg*m/s, nearly double the momentum of the cal. 12

No wonder they went through...

[LaCroix]

As an afterthought - i don't know if they can even produce ammunition on-site. It's one thing to find iron ore and produce stuff, but chemical propellants? I think ammo would be the 'valuable cargo' that needed to be imported.

It's not that difficult: it's all nitrates, and they have a crapload of raw materials for that right outside the base.

I stand corrected.

[adam_grif]

Even being able to take out the helicopters was pretty suspect. The arrows weren't scratching the canopies on those things, but then the dive bombing apparently added enough speed to make it punch clean through the whole way and then spear through a human and come out behind them. This is questionable.

I can't find a source for it now, but I distinctly remember reading that the failed Comanche helicopter's canopy was built to be able to shrug of 12.7mm NATO rounds.

You are confusing energy and momentum. there is a whole lot of whoop-ass stored in a six feet long piece of hardwood in movement.


A cal 12 bullet weights arount 40 grams with 900m/s -> 0.04*900 = 36 kg*m/s; so let's take that as benchmark

A normal 28" fir/cedar arrow weights about 30-40 grams. An war arrow would be made of oak or similar hardwood, and a different tip, easily doubling that weight(70-80 grams). It's 2,5 times longer -> 175-200

Also, the longer arrow would be much thicker to work with that bow (half to 3/4 inch diameter as in comparison to the 11/32 inch of a normal arrow) who seemed to achieve flight speeds of 150 ft/s or more. So you can assume those arrows weighting easily about 500 grams. That's no toy anymore!

The bow alone:
0.5 kg*50m/s= 25kg*m/s

This would obviously not penetrate, although scratches are quite possible

But in dive:
The banshee is said to reach dive speeds of ~140 knots - 260km/h -> 72 m/s; that's more than the arrow alone would achieve!

0.5*(50+72)= 61kg*m/s, nearly double the momentum of the cal. 12

No wonder they went through...

Some physics and ballistics questions:

- Isn't there more to it than just momentum? It was my understanding that lighter, faster things were considerably more effective at penetration than larger, slower ones. This is why APDS / APFSDS rounds are used, yeah?
- If the arrow has a diameter of .75 inches, wouldn't it also need more energy and/or momentum proportionally than the .50 round to punch a hole, because it has to go through more glass?

[LaCroix]

Momentum is penetration. You can fire an arrow through sandbags, a bullet will be stopped. Like those cockpit doors. Bulletproof, but an arrow still penetrates.

It's glass, once you have a hole, there will be some shattering, and the spiderweb of cracks next to the larger hole will severely weaken the surrounding glass. You also have the cutting effect of the blade-shaped tip (mechanical advantage), which will make a large slit to be penetrated by the shaft, instead of a round object pushing through.

Don't forget, that arrow has about twice the momentum of a .50 bullet. And it only has to hit the Pilot behind.

[PeZook]

- Isn't there more to it than just momentum? It was my understanding that lighter, faster things were considerably more effective at penetration than larger, slower ones. This is why APDS / APFSDS rounds are used, yeah?

Not really. The famous American APFSDS round is about impact geometry, and it's made of depleted uranium precisely because DU is dense and heavy (it also self-sharpens while penetrating and doesn't shatter easily). It's a modern-day bodkin arrowhead.

Furthermore, there's nothing indicating the canopies are armored at all. Quaritch could riddle one full of holes using his rifle and sidearm: unless the gunships have canopies made out of an entirely different material for some reason, we don't have any reason to assume arrows won't penetrate when fired from close range, at a right angle and from a diving banshee.

[adam_grif]

- Isn't there more to it than just momentum? It was my understanding that lighter, faster things were considerably more effective at penetration than larger, slower ones. This is why APDS / APFSDS rounds are used, yeah?

Not really. The famous American APFSDS round is about impact geometry, and it's made of depleted uranium precisely because DU is dense and heavy (it also self-sharpens while penetrating and doesn't shatter easily). It's a modern-day bodkin arrowhead.

Furthermore, there's nothing indicating the canopies are armored at all. Quaritch could riddle one full of holes using his rifle and sidearm: unless the gunships have canopies made out of an entirely different material for some reason, we don't have any reason to assume arrows won't penetrate when fired from close range, at a right angle and from a diving banshee.

Right, so we can chalk this one up to further RDA lack of foresight.

[Starglider]

Right, so we can chalk this one up to further RDA lack of foresight.

They're transport helicopters. An armored canopy would cut into payload. Real life transport helicopters do not have canopies sufficient to resist three foot javelins hitting them at 100 mph for this reason. The problem was more that those transport VTOLs were there at all. If the shuttle had not been going so ridiculously slowly, there would have been no need for them as escorts.

[NecronLord]

Right, so we can chalk this one up to further RDA lack of foresight.

You're forgetting. Every extra kilo you ship out to Pandora is going to be another million dollars or something. Why would they send heavily armoured choppers, when the choppers are basically for ferrying people around and shooting at the wildlife?

It's not lack of foresight to make something capable (more than capable) of mission role, any more than it's lack of foresight on your part if you don't take out a deep sea diving suit with you to go out and buy groceries. Sure, a random act of aggression may result in the USN kidnapping you, chaining you to an anvil and slinging you to the bottom of the sea, but the fact that you've not equipped yourself for that doesn't mean you've no foresight, it means that things happened you would not reasonably expect to happen.

The guy that decided what type of helo to purchase couldn't reasonably expect full scale war (which they handily won anyway until a giant swarm appeared) with the locals could he?

[adam_grif]

You're forgetting. Every extra kilo you ship out to Pandora is going to be another million dollars or something. Why would they send heavily armoured choppers, when the choppers are basically for ferrying people around and shooting at the wildlife?

What? The helicopters, AMP suits etc were all manufactured on Pandora. All they had to ship out was the people, the manufacturing gear and so on. Everything else was done in situ.

I say lack of foresight for exactly this reason - they didn't see the full scale conflict coming, even though Colonel Douchebag McTriggerhappy was planning it for months upon months. I'll grant that you wouldn't normally expect to have to worry about something like that (I don't think anyone is really disputing that the ending victory was rather contrived for the Na'vi), but it seems like one of those things you'd just include in design unless there was some compelling reason not too.

You and Starglider both say weight, but then again we've already got a low gravity environment with more than suffiiently powerful engines. Does reinforced glass really weigh that much more? I don't know, maybe it does weigh a million kilograms. But they didn't haul these things from Earth.

[NecronLord]

What? The helicopters, AMP suits etc were all manufactured on Pandora. All they had to ship out was the people, the manufacturing gear and so on. Everything else was done in situ.

That's not in the film. It may be in the survival guide, or it may be from the scriptment, but it's not in the film.

I say lack of foresight for exactly this reason - they didn't see the full scale conflict coming, even though Colonel Douchebag McTriggerhappy was planning it for months upon months. I'll grant that you wouldn't normally expect to have to worry about something like that (I don't think anyone is really arguing that the ending victory was rather contrived for the Na'vi), but it seems like one of those things you'd just include in design unless there was some compelling reason not too.

And the guy that decided what Helos to buy would have done it years ago, probably on Earth. Look at the fuss we've got about getting new transport helicopters to the British army in Afganistan.

You and Starglider both say weight, but then again we've already got a low gravity environment with more than suffiiently powerful engines. Does reinforced glass really weigh that much more? I don't know, maybe it does weigh a million kilograms. But they didn't haul these things from Earth.

Mass not weight. It's a matter of mass to haul it from Earth.

Now you're just making stuff up. Fine. The magnetic field of Pandora is so strong that anything made of iron wouldn't get off the ground, and they're actually made of lightweight materials for that reason. See, I can make stuff up too.

[Shroom Man 777]

That's Independently Targeting Particle Beam Phalanx to you, buddy. And it's a puppy, not a baby.

For shame, Shroom Man. For shame.

Look into my eye.

[adam_grif]

That's not in the film. It may be in the survival guide, or it may be from the scriptment, but it's not in the film.

Well then, now you know I guess.

And the guy that decided what Helos to buy would have done it years ago, probably on Earth. Look at the fuss we've got about getting new transport helicopters to the British army in Afganistan.

That's not so much a concern. The reason they chose it was because it didn't use exotic materials that they couldn't make or find on Pandora easily. Pandorapedia claims it was a late 21st century design utilized for this reason.

The AT-99 “Scorpion” Gunship is a twin turbine, tiltrotor VTOL vehicle. It carries some light ballistic composite armor around the cockpit, and has a canopy formed of a ballistic laminate of optically clear aluminum oxynitride and polycarbonate. Weapons are controlled by a standard on-board targeting computer with pilot override for Manual Flight Mode in high EMF conditions. The pilot’s display is a wrap-around Immersive HUD.

So if my memory serves me correctly, that's in fact not glass, and is the same material the transparent gun-shields have (mounted on IDF tanks and trialed on some US ones iirc). I have no idea how this rates compared to actual glass in terms of strength, but I imagine it's better otherwise they'd use glass gunshields instead.

Mass not weight. It's a matter of mass to haul it from Earth.

Yes but it's a matter of weight to haul cargo around on pandora in gravity. Weight was correct for my response to Starglider but not you. Momentary oversight, please forgive me.

Now you're just making stuff up. Fine. The magnetic field of Pandora is so strong that anything made of iron wouldn't get off the ground, and they're actually made of lightweight materials for that reason. See, I can make stuff up too.

What was I making up? In situ manufacturing of the choppers? That's on Pandorapedia, which is canonical as best as I can tell. That pandora has a lower than Earth gravity? Also there, but can also be found in the offhand comment about Pandora's low gravity making you weak from Colonel Badmean. That the engines are more than powerful? It's designed to work on Earth in full Earth gravity, so it should be more than adequate to do the job.

[PeZook]

You and Starglider both say weight, but then again we've already got a low gravity environment with more than suffiiently powerful engines. Does reinforced glass really weigh that much more? I don't know, maybe it does weigh a million kilograms. But they didn't haul these things from Earth.

You need to make the armored glass first in order to install it.

You also need to be making explosives, ammo, mining gear, weapons, air filters, furniture, toilets, dining trays and a million other things, too.

Now, ordinary glass can be made with sand. Simple policarbon transparent canopies can be made from the same material you make your safety goggles and windows from. Canopies armored to resist to 12.7mm bullets require a specialized material with a separate production line. Or lines, since you also need to make the ingredients.

[adam_grif]

You need to make the armored glass first in order to install it.

You also need to be making explosives, ammo, mining gear, weapons, air filters, furniture, toilets, dining trays and a million other things, too.

Now, ordinary glass can be made with sand. Simple policarbon transparent canopies can be made from the same material you make your safety goggles and windows from. Canopies armored to resist to 12.7mm bullets require a specialized material with a separate production line. Or lines, since you also need to make the ingredients.

Scroll up a bit, it's not glass. It's Aluminium oxynitride.

http://en.wikipedia.org/wiki/Aluminium_oxynitride

Real stuff apparently. Someone should inform Scotty, he'll be thrilled they finally invented transparent aluminium.

[Shroom Man 777]

Take note that while those RDA in situ fabricators are convenient, they are by no means Star Trek replicators or shit. While it's easy to say "lol fabricators", it probably entails a whole shitload of manhours as well as a a supply chain and shit that diverts from the primary unobtanium mining.