Talk-Polywell.org

The final quote in the nextbigfuture article doesn't bode well for the project's survival right now.

You know, if they REALLY wanted to drive down the costs of such a system over the long term, they would invest in developing nuclear powered jets that don't need to refuel.

Betruger wrote:The final quote in the nextbigfuture article doesn't bode well for the project's survival right now.

ABL relies on a chemical laser. They need to switch over to solid state lasers, which should be possible in relatively short order.

EricF wrote:You know, if they REALLY wanted to drive down the costs of such a system over the long term, they would invest in developing nuclear powered jets that don't need to refuel.

Been there, done that.

Pentagon officials declined to say how far the aircraft was from the missile, saying the information was a military secret. But analysts have said the distance may have been about 100 miles.

[The ISS] is maintained at an orbit between 278 km (173 mi) and 460 km (286 mi) altitude

Wow, we're approaching the kind of distance where a satellite could shoot down a missile. Hello Star Wars! But then, a range that barely lets the laser strike from orbit would mean it can only shoot straight down, which is pretty impractical. But:

"The reality is that you would need a laser something like 20 to 30 times more powerful than the chemical laser in the plane right now to be able to get any distance from the launch site to fire," Gates said.

2,000-3,000 miles then, desired. That's real orbital potential. Not that we'd necessarily want it all in space. Hard to maneuver satellites, hard to reload chemical systems and chemical propellants. But it's nice to imagine.

EricF wrote:You know, if they REALLY wanted to drive down the costs of such a system over the long term, they would invest in developing nuclear powered jets that don't need to refuel.

Nuclear as in fission? Yeah, it's been looked into. By both sides.

Anyway the laser is a chemical laser; it's only got about 20 shots.

On the other hand, with large quantities of high-voltage electricity available...

93143 wrote:

EricF wrote:You know, if they REALLY wanted to drive down the costs of such a system over the long term, they would invest in developing nuclear powered jets that don't need to refuel.

Nuclear as in fission? Yeah, it's been looked into. By both sides.

Anyway the laser is a chemical laser; it's only got about 20 shots.

On the other hand, with large quantities of high-voltage electricity available...

Or polywell

Are one of these jets large enough to contain a 100MW Fusor?

Are one of these jets large enough to contain a 100MW Fusor?

Of course, but is a 100 MW Fusor big enough to power one of these jets?

Are one of these jets large enough to contain a 100MW Fusor?

One of the problems with fusion-powered flight is the high ignition cost.

Jet fuel requires very little additional energy to ignite. A 100MW Polywell probably needs around 10MW.

Of course, since the fuel has such ridiculously high specific impulse, I suppose you could just only land at places with "ignition stations."

TallDave wrote:

Are one of these jets large enough to contain a 100MW Fusor?

One of the problems with fusion-powered flight is the high ignition cost.

Jet fuel requires very little additional energy to ignite. A Polywell probably needs around 10MW.

Of course, since the fuel has such ridiculously high specific impulse, I suppose you could just only land at ignition stations.

10 MW for 1 usec = 10 joules.

EricF wrote:Or polywell :P

That's what I'm talking about. An aneutronic Polywell produces high-voltage electricity natively. A fission core does not.

Are one of these jets large enough to contain a 100MW Fusor?

Yes (assuming you mean Polywell), but why would you want to do that? It would require so much shielding that it would never be able to take off. (You could use shadow shielding, but that results in severe operational constraints - ie: everything not shadowed has to be rad-hard, and no one can approach from the sides or back while it's running.) Also, 100 MW is only slightly more than the core power of ONE of the 777's engines.

Now, a 6 GW Polywell is a different story. A 747 is too small for it, so you'd have to design a new airframe. But it might just be VTOL-capable, even with full shielding on the reactor... and 6 GW can power one hellacious FEL...

...heck, why not go for a supersonic design while you're at it? With that much engine power and basically no fuel constraints, what's to prevent it?

Of course, since the fuel has such ridiculously high specific impulse, I suppose you could just only land at ignition stations.

Just leave it running unless you REALLY need to shut it off. That's what truck drivers do.

Looks like they caught it in the boost phase, might be harder to target on the way down.

IIRC the plan has always been reported as boost phase kill.

Actually 100 miles horizontally has a lot more air molecules in the way than 100 miles straight down.
So the range is in the ballpark.