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More on JSF Laser System
An anonymous reader writes "Seems Lockheed Martin has won a contract to equip future versions of the Joint Strike Fighter with a 100-kW laser. Housed in a dome within the aircraft, the laser's turret would emerge for firing [sound familiar?], and the laser itself is spec'ed to achieve airborne and ground kills at a distance of more than six miles. The problem? According to this Aviation Week article, Lockheed Martin has to figure out how to dissipate 900 kilowatts of heat. Maybe the Finnish airforce could value-add to the OEM model." We mentioned this earlier.
900Kw of heat, and only a 100Kw laser? Wow, not to effcient is it?
Very efficient for a laser. Most lasers get less than 1%.
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
Watts is a measure of power, i.e. energy per unit time. So, to ask how long it takes to deliver 100KW is nonsensical. Did you perhaps mean, how long can this thing fire for continuously, i.e. how much energy can I fire at the target in a burst?
Actually, the F22 and probably at least some other modern fighters use bellows tanks in it's fel tanks to cool engine oil. Basically you pump hot oil from the engine into the tanks which are surrounded by thousands of gallons of fuel in order to cool it down.
Along the same lines it is very common for automobiles to have their fuel pumps inside the fuel tank for the same reason. If you live in a hot area there is a pretty good chance that people who run their cars frequently near empty go through more fuel pumps than those who don't.
It used a hydrocarbon fuel not very different from kerosene.
Very different from kerosene. Most military jet aircraft run on JP-5 or JP-8, which are essentially aviation kerosenes.
The SR-71 runs on JP-7. JP-7 is a more viscous fuel with a low vapor pressure and a very high flashpoint. So high, in fact, that the SR-71 can't start its own engines. To light the fires on a Blackbird takes a chemical ignition system, where the ground crew squirts a measure of tetraethylborane into the engines. TEB is actually hypergolic with JP-7, and the resultant explosion starts the engines.
The airframe heats up to 1000 degrees F in high mach flight, and so it has to be built to fit together nice at the higher temperature. When it's on the ground and cool, it does indeed leak fuel like a sieve. And yes, they do pump fuel from tank to tank in flight to cool hot spots.
Dear lord, what a plane. 5.2 thrust-to-weight ratio. 3200km/h. 85,000 ft ceiling. 1100 C inlet temperatures. 2000 degree combustion exhaust. Has successfully evaded over 4,000 SAMs.
Like, wow.
I work in a laser lab, were the laser we work with (an Argon Ion) puts out a maximum 15 watts of power (of multiple wavelengths of visible light) in a ~5mm diameter beam.
At 1/2 watt, it will blind you immediately if your eye passes in front of it.
At 3 watts, it will burn through a piece of paper.
At 6 watts, it's burning through my sleeve.
At 8 watts if I accidentally wave my hand through it, it will cause blisters to form several minutes later.
At 10 watts, our power meter starts smoking and our mirrors begin to get these ugly burn marks on them.
At 15 watts, it'll burn through an aluminum can.
This is for a continuous wave laser (one that doesn't pulse). Now you can imagine what 100,000 watts will do:). The question is, seeing as how this must be firing in pulses, what is the pulse length? Minutes? Seconds? Milliseconds?
I'm also curious what wavelength it is firing at. I didn't notice it in the article (but I definitely could have missed it). Anyway, I hope that helped answer your question. Maybe some other slashdotters out there have worked with more powerful lasers?
JoeRobe
The best way to predict the future is to invent it.