Talk-Polywell.org

Now that might work. Isp = 10,000 seconds gives Ve= 98100 m/s so let the SSTO produce 6 MN of thrust gives a mass flow, mdot = 61.16 kg/s, with engines burning for 600 seconds to reach orbit at 9.2 km/s. I calculate MR = 1.09832 and reaction mass (fuel) expended is about 36.7 tonnes. So given an SS...

Skipjack wrote:

Like I said, you have a reading comprehension fail.

Back to personal attacks again, hu?

Do you even care if you make any sense? AcesHigh showed every indication of having completely failed to understand GIThruster's argument. It's not a personal attack to point this out.

Just a thought: do we take into account that movement (velocity) changes the light cone, so what constitutes the far-off distant mass also changes? The "edge parts" that swap would be left with some net momentum. I thought of that, but as I understand relativity, it doesn't actually work that way, ...

I should go to bed, but it seems to me that it is in fact the same issue. If the force were exerted on a static background, no configuration could ever result in a PMM2. Linear operation as a 'cosmic MHD turbine' could generate power, but the flywheel idea wouldn't. No, the velocity and orientation ...

I just said that. The trouble is that one way or another it's more complicated than that, which is what my post is about.

The momentum acquired by the thruster needs to have a partner somewhere to satisfy Newton's 3rd. Something, ultimately, acquires an equal and opposite momentum, and it isn't part of the thruster. That's the whole point of this exercise. Let's call it the "far-off active mass". The minimum amount of ...

I'm not following your question where you write: "This raises an interesting question - if the thrust efficiency of a Mach-effect device is in principle unlimited, how does the average velocity of the stuff being pushed on always match that of the thruster? " Can you rephrase this? In order to exer...

Darn it, I explained this to you guys already. Theoretically, it doesn't matter what the thrust-to-power ratio of a Mach-effect thruster is - with a sufficiently high rotor tip speed (ie: thruster speed), you can generate net power. Don't try to compare force and power directly; physics doesn't work...

Brett seems to have neglected the fact that the low density of the ambient gas means it responds very quickly to a given stress distribution, so the actual developed viscous stress pattern at a finite time following an instantaneous disturbance will be of minimal magnitude. Sure, the dynamic viscosi...

To be honest, I mostly added the "armour" as an afterthought, because that's part of what battleships are known for. The main idea was a large gun platform with strong defenses. With enough laser AA, it could become extremely expensive to launch enough missiles to score a hit. And yes, it would prob...

I think railguns and lasers have different uses. Lasers against approaching cruise missiles and planes. Railguns against enemy ships and targets on shore. Exactly. And these weapons tend to be large and power-hungry. A heavily-armoured nuclear-powered (or fusion-powered) battleship with big railgun...

Most of the complaining about laser weapons (especially the FEL) seems to revolve around space/mass/power difficulties, and railguns seem to have continuous-fire issues too. With both lasers and railguns becoming important, does anyone think it remotely plausible that battleships might make a comeba...

NASA has an unfunded SAA with ULA to finish manrating Atlas V. They already gave them $6.7M a while back to come up with an Emergency Detection System, which is all it really needs.

More generally:

Boeing CST-100 (Atlas V): $460M
SpaceX Dragon (Falcon 9): $440M
SNC Dream Chaser (Atlas V): $212.5M

Pretty much as expected, at least on NSF. Liberty was a bit new for this one, and Blue Origin is less far along and doesn't really need the money...

That's comparable to the power-to-thrust ratio of a DFP engine.