In assault on American values, Lockheed blasts pickup with raygun Lockheed Martin has demonstrated a new laser cannon prototype by using the weapon to punch through the engine block of a small truck from a mile away. The device, dubbed ATHENA (Advanced Test High Energy Asset), was – according to reports – able to burn through the vehicle's engine manifold "in a matter of seconds," disabling …
I think you might need to put in a tad more than 90kW in order to get 30kW out :-)
It's lucky there are engines that produce more than 90kW then!
As always it depends on the technology, but some laser systems have efficiencies far higher than that.
And I doubt it was fired continuously for very long. If the prototype has to illuminate the target for a minute (which it probably didn't) it only needs a battery pack or capacitor capable of delivering 500Wh (multiplied by the efficiency factor of whatever technology you're using, which could be anywhere from 1.5 to 4 based on some quick research).
well if your laser could do as much damage as that 120mm at similar ranges. the advantage would be not having to carry large quantities of explosives next to the crew.
This could also mean less weight or more armour. assuming you dont have to replace the shells pound for pound with fuel or batteries.
Electricity is a wonderfully adaptable thing, e.g. if all your weapons were lasers, you could divide your power budget more flexibly, like providing more speed if you don't need to fire. However, the batteries and fuel required to store the energy needed to create the electricity would probably not be much safer to transport than explosive munitions.
"A sabot round from the Challenger 2 tank will make a bigger mess of the car than the laser did too. And it would take about 1 second."
Assuming the problem is to immobile the target rather than obliterate it, there might be less chance of getting any useful intelligence out of the occupants afterwards with a sabot round than a laser aimed at the engine.
Even batteries could give you several hundreds of kW if the duty cycle was long enough; moreover, reasonably small engines of hundreds of kW are commonly available.
What's more conceivable and disturbing is that it's possible that such devilish machinery could be more likely to get into the hands of terrorists than it would be for nukes to do so.
My Renault Scenic outputs 90Kw.
Good point. To put the directed energy weapon prototypes in perspective a RPG delivers very roughly a million times that amount of energy from half a mile away at a very low cost.
The main point of expensive weapons system is to funnel tax revenue such that a large amount of money finishes up, via corporations, in the control of a very few individuals.
"a RPG delivers very roughly a million times that amount of energy"
kW is a unit of power not energy.
If you meant 90 kJ are you seriously suggesting that a RPG delivers 90E9 J ? For comparison TNT has an explosive yield of ~4 MJ/kg.
Please show your workings ! (90E9 J is the rough yield from > 20 tonnes of TNT) That's some RPG. Shoulder launched ?
"a RPG delivers very roughly a million times that amount of energy" ... kW is a unit of power not energy... If you meant 90 kJ are you seriously suggesting that a RPG delivers 90E9 J ? For comparison TNT has an explosive yield of ~4 MJ/kg.
Please show your workings ! (90E9 J is the rough yield from > 20 tonnes of TNT) That's some RPG. Shoulder launched ?
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I am old now (and possibly senile), but when I did this sort of thing as an explosives chemist for MoD over 40 years ago the rough rule of thumb was 1 cubic inch of composite HE generates 7million HP when it goes bang.
Many of us get confused about energy power and and the rate of doing work. I can get confused with units because when I was at school, we learnt ft-lb/sec, then c.g.s, then m.k.s; and then, when I was working, SI units. So, to see if I am in the right ball park, a few numbers:-
Petrol (which is a lot more energetic/Kg than TNT as it has no oxygen contained within it) has 8 MJ/L or 44.4 MJ/kg - In a 90 Kw car, that 1 kg would allow it to travel very roughly 15 km in 15 mins - The engine uses that 44 MJ in 900 seconds or very roughly 0.05 MJ/s (It doesn't because petrol engines are ~30% efficient).
TNT only has 4.7 MJ/kg. The more powerful composite high explosives would have >5 MJ/kg. A RPG warhead contains ~0.2Kg of explosive so that would be ~1 MJ. The velocity of detonation of composite is ~8000 m/s, and the maximum distance the detonation front has to travel within the charge is ~0.1 m. So the explosion takes 0.1/8000 sec or 1/80000 sec, therefore the RPG warhead explosion generates 1 x 80000 MJ/s or 80 GJ/s. Your 90E9 J value (90 GJ) has no time units.
The calculation based on the MoD rough rule of thumb:-
1HP = 7.46 E-7 GJ/s, so 7 million HP = 7E6 x 7.46 E-7 GJ/s or ~5 GJ/s. The warhead contains roughly 0.2kg of explosive with a density of ~1.5 which is ~130mL or roughly 8 cubic inches, so the total yield is 8 x 5 GJ/s or ~ 40GJ/s - Obviously this is about half of the "theoretical value" but allowing for differences in explosive material, velocity, and energy transfer; it is pretty close.
The secret of the large amount of destructive power in a small device is the very short time that it takes to be generated (The velocity of detonation within the charge being 8000 m/s). So, no you don't need >20 tonnes of TNT you only need 0.2 kg. RPGs can be particularly effective as they rely on the "shaped charge" effect, where most of the charge's energy is used to project a similar mass of copper in a jet with a tip velocity of ~10km/s and a temperature of ~500C into the target.
High explosives are generally classified as such if they have a detonation velocity of >3000 m/s. Gunpowder (black powder) as used in fireworks only has a deflagration velocity of 600 m/s and does not 'explode' unless confined.
"a RPG delivers very roughly a million times that amount of energy"
Your workings still don't show that !
It mght well deliver a million times the power over the tiny timescale of a detnation but by your own calculations it still only delivers ~ 1MJ of energy. I'm not disputing the fact that a RPG will make a big hole in things ( and indeed in my lab days I've had very small amounts of material do suprising damage)
This post has been deleted by its author
I admit in my first reply to your original post I should have really just pointed out that the use of 'energy' instead of 'power' was the problem I had with it.
Yes, my use of "energy" was unfortunate. I should have qualified it with the word "destructive"; but as I said, I am possibly senile; and I believe that I was using the term loosely. As you have gathered I was (am) a chemist too, and have been for 44 years with Chartered status for over 30 years, so I do actually know this stuff.
I suspect that you (perhaps like I would have done before I worked with high explosives) looked at the numbers inferred by my post and thought that they could not possibly be correct - Largish amounts of energy liberated in a very short period of time is outside normal experience for most people - Hence your incorrect assumption that you would need a RPG with a 20 tonne charge.
HP, as you know, to be relevant, requires a time unit. That is why I included the car calculation in my reply to you - This shows a larger energy over a much longer time - If the petrol was mixed with a stoichiometric amount of a condensed phase oxidizer (a Sprengel explosive) and then detonated it would also give a large GJ/s result because the detonation velocity would also be in the order of Km/s and the time taken would be similar to a military HE.
Energy is the ability to do work - An explosive is powerful because it does that work in a very short time.
Regards, Tim
"I suspect that you (perhaps like I would have done before I worked with high explosives) looked at the numbers inferred by my post and thought that they could not possibly be correct -"
Sorry no, I'm quite happy with small energy, large power in short time. In a more relevant example for The Reg - a few Joules, giving a powerful flash of short duration in a flash tube.
My gripe was just about the use of 'energy' -( I'd just heard an idiot on radio news totally mixing up power and energy )
"Hence your incorrect assumption that you would need a RPG with a 20 tonne charge."
That was just to illustrate the absurdity of - "a miilion times the energy". Sounds like ths was a cross-purpose problem between us
All mob on disability benefits blind from now on. Theoretically, this usage is prohibited by the "spirit" of the Geneva conventions. Practically, such formalities have never stopped US before. In any case Geneva conventions do not apply to civil wars and police actions. So perfectly legal when used on a MOB.
> And it'd be devastating at considerably lower powers too (which would make it even more practicable).
And if it were an IR laser, they could torch hair with less risk of political blowback from burning a lot of retinas. However, I failed to consider the very narrow beam; unless the cannon is exactly at head height and the crowd is on a level field, not much action. Even then, variable height mobs would be a problem.
The power output by itself matters much less than the duration this level had to be sustained (to burn the target).
Now, there is number of questions this whole exercise (unwillingly paid by taxpayers) brings.
I'm curious how much different would be the outcome if the truck was somewhat more shiny/new (though poor schmucks that will be targeted will surely be riding some rusty tin cans).
And then, they were shooting the front of approaching vehicle (albeit at less then favorable angle). Add some lateral movement of the target, some other objects getting in the way of the laser beam plus unstable (real world) base of laser gun and even the rusty POS may have enough time to close on the fancy weapon carrier and blow itself up (together with laser troopers).
It would be also interesting to test if grease (or other melting substance, possibly sandwiched under some plastic cover) smeared on the targeted surface released enough smoke (when lased upon) to create low cost/low tech laser shield. I'm quite sure there's many other cheap ways to defeat it (but DIC will claim otherwise as it has to sell something new and expensive and Army has enough guns already).
Coatings aren't likely to stop a powerful laser for long. The moment it distorts, it creates a vicious cycle. They made that determination when thinking of using a laser to stop a ballistic missile.
As for being on the move, can't computers compensate for various degrees of motion and still be able to keep a bullet-firing gun on target? Against that, a laser shooting at relativistic velocities should be cake.
"can't computers compensate for various degrees of motion and still be able to keep a bullet-firing gun on target"
While knowing nothing about weapons systems, I wouldn't have thought this is too tricky. Watch the accuracy of aerial TV cameras for e.g. in F1*, computers are compensating for the flight of the helicopter, turbulence/wind etc. and the output image is incredibly stable.
If they can do it with cameras at a commercial level, I have little doubt they could do it with lasers at a military level.
* F1 may be a bad example as the cars have a silly amount of technology in them and for all I know are providing some signal for the camera to track.
And I'd like one for those pedestrians who think that because the *cars* have stopped, it's ok to stroll across the road between them, not considering that there may be a biker filtering perfectly legally between the stopped vehicles...
That sounds like a good idea, maybe even Darwin would approve, after all it would remove some of the dumb-as-f*** pedestrians who seem to own phones that are smarter than they are.
If it was powerful enough it may even be able to take out the black-cab drivers who u-turn without warning.
No just lots of people who wished that cyclists would read and obey the current highway code.
That works both ways… it's that same law that says though shall pass cyclist with a minimum 1 metre clearance. 'Least here in Queensland it is.
'Course I'd like ot not have to use roads or footpaths: I've got some money sitting here, who do I send it to to make it happen?
You mean like all those drivers out there who all know and obey the current Highway code?
The ones who don't blast past cyclists with a cigarette paper's clearnace, the ones who don't overtake cyclists and then turn left, the ones who don't stop illegally on zig-zag lines or at the advanced stop line for cyclists, the ones who...?
BTW before anyone starts with the usual BS, I also think that cyclists should obey the rules of the road, but generally they are only putting *their own* lives at risk, whereas someone who is in charge of a couple of tonnes of metal moving at high speed is putting *others* at risk when they do something stupid and dangerous.
Seems like on El Reg there must be either a) a lot of idiotic pedestrians or b) a lot of car drivers who think that if they have to sit in a queue then so should everyone else!
I don;t think you made it clear enough that you had in mind a scenario where the traffic light was green but a stationary queue of motor vehicles was present with adequate space between lanes for a cyclist to filter. It is legitimate for either a crossing pedestrian (uk, no jaywalking laws) or a road using cyclist (green light) to proceed. Both have a responsibility to avoid collisions. In the hierarchy of vulnerable road users the cyclist probably has a little more. You could make an argument of courtesy for the pedestrians to yield to the cyclist. You could also make an argument about relative levels or responsibility for either party dependent on how foreseeable it was for the other party to be there. I can only control my own behaviour so when crossing a road on foot or filtering through traffic on a bike I always try to look first and proceed at a pace where I can stop if another road user isn't taking the same amount of care. I found commuting became less stressful if I focused less on feeling wronged and more on how I could cooperate with other road users whilst still making reasonable progress. But yes, like gender politics, OS and smartphone wars, cycling issues tend to attract bloc voters (in both directions) around here
You must have been really itching to click that Reply button on a subject that's more than a year old…
Yeah, I don't doubt there are some of us on two wheels that do the wrong thing. I do what I can to avoid joining that group and most of the time, I succeed in avoiding being one of them.
Cars are bubbles of distraction these days however, and anything that alerts a driver that they are too close, is worthwhile.
In my case, the driver has to be either "driving without due care and attention" (an offence that can lead to fines and demerit points) or legally blind to not see me when I'm riding. Get too close, and you'll know soon enough.
And I want a body mounted one to deal with all those homicidal pavement abusing cyclists.
Can they build one into a T shirt for me? Just for me? C'mon, lads - with all that taxpayers' pork it can't be all that hard. Next week by tuesday lunchtime should be doable.
Bonus if it can get its power remotely from the said cyclist's personal ishinies.
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