How Far From Phasers?

Post by **Darth Wong** » 2003-04-02 12:29am

Howedar wrote:However, the time over which the recoil is expressed does make a difference. For the sake of argument, if you had a gun that recoiled a continuous 10N over 5 seconds, one could easily compensate for it and get a feeling for how much recoil there was, and correct for it, before the bullet left the barrel. If its over a hundredth of a second, not only is the instantaneous recoil much higher, but one cannot compensate for it.

Which leads us right back to barrel length. In order to achieve a high muzzle velocity in a barrel of any given length, there is a strict lower limit to the impulse required. And in order to make a railgun worthwhile, it must somehow compensate for its many weaknesses relative to a conventional gun (not least of which is the fact that it requires a portable power source, while a conventional gun does not), and that inevitably means you'd better give it a superior muzzle velocity if you're going to bother using it at all. I reiterate that if you've got that much juice to spare, lasers are the way to go.

Kuroneko · Post by **Kuroneko** » 2003-04-02 02:58am

Howedar wrote:However, the time over which the recoil is expressed does make a difference. For the sake of argument, if you had a gun that recoiled a continuous 10N over 5 seconds, one could easily compensate for it... If its over a hundredth of a second, not only is the instantaneous recoil much higher, but one cannot compensate for it.

Sure, but how much of that applies to a railgun? Even if you match the very excessive Wilhelmgeshuetze Paris Gun in barrel length (30m), a 3km/s muzzle velocity projectile will still clear the rails within 20ms.

Kuroneko · Post by **Kuroneko** » 2003-04-02 03:12am

kojikun wrote:Whats a Q Spoiling Device?

I have no idea, but Einhander's other alternative--a pulsed laser seems almost a necessity to me, with a laser's (in the visible range) tendency to deposit its energy along the surface. To have penetration, the laser should be pulsed.

XaLEv · Post by **XaLEv** » 2003-04-02 03:26am

Kuroneko wrote:
kojikun wrote:Whats a Q Spoiling Device?
I have no idea, but Einhander's other alternative--a pulsed laser seems almost a necessity to me, with a laser's (in the visible range) tendency to deposit its energy along the surface. To have penetration, the laser should be pulsed.

I found this:

Q-switching or Q-spoiling is a technique employed to produce a very high output pulse. Q- switching is accomplished by using a device to prevent the reflection of photons back and forth in the active medium. This produces a higher population of electrons in the metastable state. At a predetermined instant the Q-switch is turned off allowing the lasing action to continue producing very intense short pulses of laser radiation. Q-switched lasers produce pulses of 10 to 250 nanoseconds (ns).

Kuroneko · Post by **Kuroneko** » 2003-04-02 03:38am

Thank you, XaLEv.

Raoul Duke, Jr. · Post by **Raoul Duke, Jr.** » 2003-04-02 02:24pm

Einhander Sn0m4n wrote:How about:

A: A CO2 Pulse Laser or

B: A He/Ne Laser with a Q-Spoiling Device?

A friend of mine was talking a few years back about trying to create a portable pulsed neodymium (sp?) laser... probably the genesis of this thread, now that I think about it.

So what kind of power source would one need, and what's the current level of miniaturization vis a vis that product?

kojikun · Post by **kojikun** » 2003-04-02 05:35pm

raoul, for any serious weapon you need alot of power. that amount is the bare minimum needed, and to provide that with electrical systems is difficult due to storage. batteries simply are not that good i dont think.

gun powder and cordite, however, work rather nicely.

Raoul Duke, Jr. · Post by **Raoul Duke, Jr.** » 2003-04-02 07:55pm

Can lasers be stimulated through combustion?

Post by **Beowulf** » 2003-04-02 09:17pm

Raoul Duke, Jr. wrote:Can lasers be stimulated through combustion?

*points to ABL*

Sokar · Post by **Sokar** » 2003-04-03 01:14am

GrandAdmiralPrawn wrote:It strikes me that a laser would make a very effective anti-missile system for an aircraft carrier. Lots of room, and fuck power. You have a bloody nuclear reactor right there.

Only if you convert out a sizable chunk of the ship into turbine electrical generators....nuclear powered ships are just high tech steam powered ships in the end.

Kuroneko · Post by **Kuroneko** » 2003-04-03 03:22am

Sokar wrote:
GrandAdmiralPrawn wrote:It strikes me that a laser would make a very effective anti-missile system for an aircraft carrier. Lots of room, and fuck power. You have a bloody nuclear reactor right there.
Only if you convert out a sizable chunk of the ship into turbine electrical generators....nuclear powered ships are just high tech steam powered ships in the end.

Not so, or at least not significantly more so than currently. Many nuclear aircraft carriers have four turbines with an aggregate output of at around 280,000hp [1]. Adding a dedicated turbine for the laser would add over 52MW of power (it would probably be much easier to simply dedicate 52 of the 210MW to the laser, despite slowing down the engines). With a 25% electrical-to-photon energy conversion of a fairly efficient laser (there are lasers with higher efficiency), that's about 13MW. With a delay of 1s between shots (capacitor storage), the laser delivers 13MJ of energy per shot. That's an energy-equivalent of 5.3lbs of TNT, and I contend that it's enough to take out a missile. If you have particularly tough missiles (perhaps ones designed with lasers in mind), either increase the power or the delay between shots.