The "Real Aerospace" Thread

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Zakharra
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Re: The "Real Aerospace" Thread

Post by Zakharra »

RedDwarfIV wrote:
Zakharra wrote:
RedDwarfIV wrote:-snip-

It wouldn't even come close. Anti-tank mines would still kill the tanks. Incoming missiles/RPGs and shells would still hit and incapacitate/kill the tank. The shield mentioned in the article might work for one incoming projectile, but not for all (where would the system get the energy? Unless this SCAR shield can physically -stop- projectiles in mid-air (doubtful since velocity alone is going to be a stone bitch to overcome) and defeat the shaped charges going off, all the SCAR is is expensive useless junk. And if a SCAR is up, wouldn't that both interfere with radio communications and send up a huge 'I AM HERE!' sign for radar and electromagnetic sensors? It would also be able to be beaten down with enough hits. No shield is imperious to everything.
I refer you to the fact that one Challenger 2 survived 70 RPG hits. Another survived fourteen hits plus a MILAN anti-tank missile. The only one to ever have been destroyed in combat was killed by another Challenger. This is because the British armed forces favour armour over mobility in their tanks, hence why it's much tougher - but slower - than the Abrams. As for mines, I thought I'd read somewhere that an Abrams attempted to drive along a road that had numerous IEDs and was destroyed, while a Challenger made it over fine, However, since I can't find where I read it, you can take that with a grain of salt. In any case, in all the times a Challenger's armour has been penetrated by IEDs, it resulted in at most the loss of a leg for one of the crew. The Streetfighter upgrades should see to that, as they will be putting armour on the underside where the tank is weakest.

On SCAR:
Researchers at the Defence Science and Technology Laboratory (Dstl), which is the research and development arm of the Ministry of Defence, claim it is possible to incorporate material known as supercapacitors into armour of a vehicle to turn it into a kind of giant battery.
When a threat from incoming fire is detected by the vehicle, the energy stored in the supercapacitor can be rapidly dumped onto the metal plating on the outside of the vehicle, producing a strong electromagnetic field.
Scientists behind the project claim this would produce a momentary "force field" capable of repelling the incoming rounds and projectiles.
Although it would last for only a fraction of a second, if timed correctly it could prevent rocket propelled grenades, which detonate on impact, from reaching their target. The supercapacitor could then be rapidly recharged ready for another attack.
"The supercapacitor material can be charged up and then discharged in one powerful event to repel incoming fire.
"You would think this would require huge amounts of energy, but we have found it can be done with surprisingly small amounts of electrical power.
"Conventional armour is just a lump of metal but an RPG round can punch through more than a foot of steel. Carrying around enough armour to protect against that is extremely heavy.
"The real advantage to the electric armour is how light it can be by comparison."
Sophisticated tracking systems will also need to be developed to work in conjunction with the new armour so that incoming threats can be identified and the electrical discharge timed correctly to repel the rocket.
It is unlikely that such a system would be used against fire from small arms as the outer skin can be made to be bullet proof.
(Source: http://www.telegraph.co.uk/technology/n ... tists.html)

Since it's momentary, it's not going to interfere with communications. Besides, you know what else interferes with communications? Being dead. As for the 'I AM HERE' thing, I'll point out that we don't exactly build tanks for stealth.



I looked at the article and it was effective against current model RPGs. RPG rounds can and will get better. As will shoulder fired missiles. If a Challenger drives over a mine and it blows off the tread, the tank just becomes a pillbox. That's one of the flaws of a tank, you -can't- armor the treads on the ground, and your forcefield would be worthless against mines (which would be improving as well). It is always a race between weapons and armor. Nothing is ever static for long and the SCAR shield would be overcome sooner than later.

As for the claim of stopping incoming projectiles like missiles or the rounds of say.. an A-10 Warthog, I seriously doubt any SCAR shield could stop that. That's a hell of a lot of momentum and mass to stop, if the electromagnetic shield can effect a high velocity 30mm cannon fire to begin with. Not to mention, the mines. There's absolutely no way this shield could detect and stop a mine from going off (and there's no way it could protect the treads from a mine underneath them). While a SCAR might be useful against distant shots it can detect incoming, what of close range shots? Or the railgun if the US military gets that working for tanks? I can see the SCAR having some use for the smaller rounds and such, but it's not a panacea against everything up to nuclear weapons.


The Super Bainite armor looks interesting though.

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RedDwarfIV
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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

Didn't say it was a panacea. I said that, in combination with the Challenger 2's toughness, you'd get an even tougher tank than a tank that was already incredibly tough. As for tracks, that tank that was hit by 14 RPGs and an anti-tank missile. It slipped its tracks, but within six hours it had been repaired and was moving again.

As for the A-10's Avenger cannon, well, that's basically a constant stream of bullets. Even if the SCAR knocked down a few of the bullets, the 'force-field' effect only lasts for a split second. It wouldn't be a defence in that case.

And mines? That's what this:
Image
... is for.
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Mr.Tucker
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Re: The "Real Aerospace" Thread

Post by Mr.Tucker »

Well. Let me clarify my stance on the subject: we are talking about two different systems.

The SCAR is what was once refered to as Electro-Reactive Armor. Which means there is a thin layer of highly conductive material under whatever conventional armor the vehicle has. When the shaped charge hits, current is pumped through the layer and into the jet of metal from the RPG, destabilizing it (since it relies on very precise self-focusing properties), and causing it to have drastically reduced penetration. It was designed to work ONLY on RPGs and, perhaps, self-shaping penetrators. It has nowhere near the juice needed to vaporize a kinetic projectile from larger caliber gun (such as a tank, or even the 30mm round from the cannon of the A-10). It was not designed for tanks, because modern MBTs do not need it (western tanks use ceramic armor, which fragments and disrupts the jet, russian and chinese ones use advanced explosive reactive armor to the same effect). It was designed for light vehicles, that can't weigh anywhere near 30 tons, and has issues with supercapacitor weight and volume of fire problems. It was made for vehicles that can still be destroyed by shaped charges (APCs, Humvees), not MBTs. It is NOT a force-field (more like ''polarize the hull plating'' from Star Trek Enterprise).

The Boeing device was also a niche idea: designed for blasts (shockwaves mates), with the advantage of having greater stand-off distance. Like the SCAR it suffers from weight and volume issues. I posted it because I though it was interesting. I'm not sure how well it would function. And it will also not work on kinetic rounds. They have too much energy, and are already thermal-resilient (otherwise they would melt inside the barrel of the gun).
It uses the ''3M'' effect to cushion the blasts.
For those of you unaware, this interesting effect was discovered at a 3M factotry, where a high-speed role of tape was peeled off, creating a strange static effect underneath it, that functioned like a rubber wall, preventing objects from passing through with ease (apparently you could lean on it, but if enough force was applied, could go through it). It required quite a bit of power, and that is why the Boeing apparatus only activates it shortly. Still quite cool.

The only fool-proof defense for tanks is a combination of active protection systems (of which the best seems the AMAP-ADS) and heavy armor. And I say fool-proof with great generosity. In truth, tanks are designed to fight other tanks. Bombs and mines still kill them off quite fine, and, for the moment, aircraft. No tank is indestructible, and if it is, it doesn't stay that way for long.

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icekatze
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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

The super-capacitor device is really old news, and I doubt it is ever going to see active use unless conditions in the world drastically change. It isn't actually stopping a projectile, all it is really doing is flash melting and deforming the copper penetrator component of an RPG's shaped charge. That in and of itself is pretty cool, but it is going to use up a lot of energy and waste heat. Useful perhaps in situations where you only expect to come under sporadic fire, but not very helpful in a serious engagement.

The plasma shock-wave buffer seems even more impractical, but I guess where defense is concerned, there's no limit to how much money can be spent on the pie in the sky. (Ironic then, how hard people had to fight just to get some extra steel plates fitted on humvees, to protect them from roadside IEDs.)

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RedDwarfIV
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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

Actually, SCAR and ERA are two different systems. SCAR just puts a supercapacitor layer behind the armour because it's a good place to put it when your supercapacitor looks like a cloth sheet. ERA relies on there being an electrical differential between two plates in the armour, and the molten copper from the RPG links the two plates and acts as a conductor, getting vapourised in the process.

SCAR is specifically described as something that would physically prevent RPG rounds from reaching the vehicle.
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icekatze
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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

No. They are not two different systems.

This is a type of armor that has been in development since at least 2001, and while it has never seen field use, it has seen some testing in the intervening 14 years. The article cited from the telegraph herald is 5 years old, and in the interview that the Telegraph Herald reported on, Professor Bryn James was talking specifically about Electrified Vehicle Armor.

We know a few things about how rail guns work, but imagine a gun that could impart an anti-tank round's worth of energy into a projectile, with no rails or coils, from any direction, with only "minimal energy." Forget having a barrel on the tank, just put a metal shell on the hull and shoot it off in any direction.

Even at 100% efficiency, stopping a tank shell is going to require 5,888,000 Joules. (Assuming 4.6 kg DU penetrator and between 1600 m/s velocity. ) But it isn't going to have anywhere close to 100% efficiency.

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RedDwarfIV
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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

Oh.

Damn you Telegraph!

(EDIT)
Yeah...
Another development on the horizon is electric armour. Several years ago, the department made headlines with its so-called 'Star Trek style force-field' armour, which would supposedly repel incoming fire through an 'electromagnetic force field'. James says that, while this armour is indeed on the way, its functionality was somewhat misconstrued.
"It was wishful thinking by the journalist," he says. "The electric armour, which was misnamed force-field armour, essentially works like an old-fashioned fuse box. In the old days, fuse boxes had a wire that would vaporise if too much current flowed through it, and that's how electric armour works."
http://www.defence-and-security.com/fea ... r-4483944/

Still.

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Grayhome
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Re: The "Real Aerospace" Thread

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Siber
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Re: The "Real Aerospace" Thread

Post by Siber »

I'm still extremely skeptical. The linked forum thread is... tricky to pick through because the math and physics involved, but doesn't seem to be entirely glowing of the experimental methods. Nobody's outright built and run their own test rig, which is what would actually be needed for falsification, but it feels like the article author is buying into the hype a bit.

I'll be excited if it pans out, but as they say exceptional claims require exceptional evidence, and so far it doesn't seem like their testing rig is as... ahem, air tight as it should be, even if this is a big step in the right direction(by actually making it airtight!).
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Re: The "Real Aerospace" Thread

Post by Arioch »

I saw the Matt Damon/Ridley Scott movie "The Martian" today. I can wholeheartedly recommend it.

The trailer which I saw a few months ago angered me, because it was one of those trailers where they basically tell you everything that happens in the movie. I still think it was a terrible trailer, but it doesn't actually ruin the movie, because the movie isn't about what happens, but rather how they do it. Which is really remarkable for a science fiction movie.

The science in the movie is remarkably sound, but I do have a few nitpicks:
SpoilerShow
  1. The Mars EVA suits are very cool, but the helmets have the standard Hollywood ring of lights that illuminate the actor's face, which would make it very difficult for him to see. Minor, but such an obvious oft-mentioned gaffe.
  2. Mars wind speeds are extremely high, but the air pressure is so low that I'm not sure that any Martian gale would have the kinetic energy to threaten to tip over the Ares 3 lander and cause the crisis in the first place. And if it did, then the Ares 4 lander that Watney later uses to escape would have been tipped over in the same manner.
  3. Potatoes have a limited shelf life, of about 60-90 days. This causes two problems:
    1. The potatoes that Watney grew wouldn't last the ~400 days or so that they did, and certainly not the 4 years that he initially planned. It's perhaps true that they wouldn't rot as quickly as they would on Earth, as there might be less bacteria and fungi around, but they were grown in a compost of human waste; the hab was not sterile.
    2. The Thanksgiving potatoes that he used as seed in the first place would have had to be irradiated or freeze-dried to preserve them, and so they probably would not have been able to grow.
  4. After the hab failure, it is said that Watney can't grow any more potatoes, mentioning something about the soil bacteria being killed. But after he repressurized the hab, he still had potatoes to use as seed and the same source of fertilizer and bacteria (human solid waste) as he had before, and so I don't see any reason why he wouldn't have been able to start over just as he did before. Water might have been a problem, but they didn't mention that.
  5. The idea that the Hermes couldn't spare the fuel to make the final course correction to intercept Watney, and so had to resort to a very dangerous depressurization maneuver instead, is a bit hard to swallow... especially since they would later need to compensate for that maneuver to get back on the proper course for Earth. If they had really been redline bingo fuel, that maneuver would have killed them.
  6. Prior to the depressurization maneuver, Beck makes an incredibly dangerous untethered spacewalk along the exterior of the Hermes, twice, for no apparent reason whatsoever. He could more easily and safely (and probably more quickly) have gone through the interior of the ship.
  7. Finally, the amount of thrust generated when Watney cuts his EVA suit is greatly exaggerated both in strength and in duration; it violently throws him around the interior of the capsule, and then continues for several minutes. A very minor point, and I bow to dramatic license.

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RedDwarfIV
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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

Aside from the helmet lights, most of those are probably issues that would have been in the book. According to HOCGaming, most of the movie was accurate to it.
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RedDwarfIV
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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

(Double posting because significant time since last post)

Went to see The Martian in the cinema today. It was really good.
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What I find weird is that they ignored the landing stage on the MAV. Aries III's MAV still contained plenty of fuel, as Watney states when gathering the hydrazine for his water making device. Why wouldn't Aries IV's MAV have a similar amount of fuel? If it was empty, why didn't Watney bring the fuel with him to transfer? At the very least it would have increased the margin of error.

As for Beck's spacewalks, I think the reason for that was that going through the ship, the spacesuit might have been too bulky. After setting the bomb on the inside door of the airlock, he had to make a spacewalk because with the way the door swung, it would have either crushed or bashed the bomb on the airlock walls. That could have detonated it or detached it from the door. I think a better question is "why bother with a bomb when you could just override the internal airlock door, so both doors could open?"
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Re: The "Real Aerospace" Thread

Post by Arioch »

RedDwarfIV wrote:(Double posting because significant time since last post)

Went to see The Martian in the cinema today. It was really good.
SpoilerShow
What I find weird is that they ignored the landing stage on the MAV. Aries III's MAV still contained plenty of fuel, as Watney states when gathering the hydrazine for his water making device. Why wouldn't Aries IV's MAV have a similar amount of fuel? If it was empty, why didn't Watney bring the fuel with him to transfer? At the very least it would have increased the margin of error.

As for Beck's spacewalks, I think the reason for that was that going through the ship, the spacesuit might have been too bulky. After setting the bomb on the inside door of the airlock, he had to make a spacewalk because with the way the door swung, it would have either crushed or bashed the bomb on the airlock walls. That could have detonated it or detached it from the door. I think a better question is "why bother with a bomb when you could just override the internal airlock door, so both doors could open?"
SpoilerShow
I suspect that there was no appropriate container for the fuel, nor any way to transfer it to the capsule once in orbit.

The interior of the ship through which he would have had to move was in zero G, and it looked like there was plenty of room. Since the airlocks by definition have to be designed to accommodate a person in a spacesuit, I don't buy that he couldn't fit through the door. But the point is that an untethered spacewalk would have been just as slow, not to mention unbelievably dangerous.

I wondered about the bomb thing myself, but I think it's reasonable to expect that the airlocks were designed so that the outer doors wouldn't open unless the inner doors were closed, and there wasn't time in the 10 minutes or whatever they had to hack around it. (Not that 10 minutes is enough time to make a bomb either...)

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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

Arioch wrote:
RedDwarfIV wrote:(Double posting because significant time since last post)

Went to see The Martian in the cinema today. It was really good.
SpoilerShow
What I find weird is that they ignored the landing stage on the MAV. Aries III's MAV still contained plenty of fuel, as Watney states when gathering the hydrazine for his water making device. Why wouldn't Aries IV's MAV have a similar amount of fuel? If it was empty, why didn't Watney bring the fuel with him to transfer? At the very least it would have increased the margin of error.

As for Beck's spacewalks, I think the reason for that was that going through the ship, the spacesuit might have been too bulky. After setting the bomb on the inside door of the airlock, he had to make a spacewalk because with the way the door swung, it would have either crushed or bashed the bomb on the airlock walls. That could have detonated it or detached it from the door. I think a better question is "why bother with a bomb when you could just override the internal airlock door, so both doors could open?"
SpoilerShow
I suspect that there was no appropriate container for the fuel, nor any way to transfer it to the capsule once in orbit.

The interior of the ship through which he would have had to move was in zero G, and it looked like there was plenty of room. Since the airlocks by definition have to be designed to accommodate a person in a spacesuit, I don't buy that he couldn't fit through the door. But the point is that an untethered spacewalk would have been just as slow, not to mention unbelievably dangerous.

I wondered about the bomb thing myself, but I think it's reasonable to expect that the airlocks were designed so that the outer doors wouldn't open unless the inner doors were closed, and there wasn't time in the 10 minutes or whatever they had to hack around it. (Not that 10 minutes is enough time to make a bomb either...)
SpoilerShow
It's mentioned in 2001: A Space Odyssey when HAL flushes Discovery One's atmosphere that the airlocks are designed to be idiot proof - but aren't designed to prevent someone with intent from opening both doors. And yeah, that bomb got built far too quickly. Your point about the spacewalk is taken.

As for MAV fuel, I'm not talking about using it in space. I'm talking about using the Aries IV MAV's landing stage as a first lift-off stage. As for transferring the fuel, what I meant was taking the Aries III MAV's landing stage's fuel and putting it in the Aries IV MAV's first stage. As for suitable containers? The fuel looked like little shiny pebbles. Put them in a metal box, then wrap the box in insulation. He got insulation from somewhere when he picked up the RTG.

Speaking of the RTG, I wonder why he never tried hooking that up to the rover?
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Re: The "Real Aerospace" Thread

Post by Arioch »

The Lunar Reconnaissance Orbiter photographed the crash site of the Apollo 16 S-IVB stage.

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Re: The "Real Aerospace" Thread

Post by Roeben »

RedDwarfIV wrote:*snip about RTG*
This is a month late but, the RTG didn't produce energy, it produced heat. The rover didn't have the equipment necessary to convert heat into electricity.

Also, nice picture of apollo 16 :lol: .

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

RTG stands for Radioisotope Thermoelectric Generator. The entire purpose of an RTG is to take thermal energy from radioactive decay and turn it into electricity.

The components for maintaining a thermal gradient, the radiators, were clearly visible in the movie even.

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Re: The "Real Aerospace" Thread

Post by RedDwarfIV »

Roeben wrote:
RedDwarfIV wrote:*snip about RTG*
This is a month late but, the RTG didn't produce energy, it produced heat. The rover didn't have the equipment necessary to convert heat into electricity.

Also, nice picture of apollo 16 :lol: .
A) Heat is energy.
B) He used it for power in the book. Cut an hour off the rover's charge time IIRC.
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Re: The "Real Aerospace" Thread

Post by Roeben »

Maybe I didn't make myself clear enough.

He didn't use the RTG for energy for the rover, the electricity he saved comes from not having to operate the built-in rover heater. The rover either couldn't tap enough energy out of the RTG to do anything at all as it was designed to only do the fuel conversion for the ascent stage, or the rover simply didn't have the right power plug.

Yes, heat is energy, but the rover didn't directly use that energy, which is the point of the argument. Even if it could, it couldn't output enough energy to drive the rover for even remotely close to an hour per day. The rover was big and carried a lot of weight, and the RTG doesn't output much.

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