Using atmosphere as propellant

WizWom · Post by **WizWom** » Tue Jul 19, 2011 10:12 pm

KitemanSA wrote:
WizWom wrote: So, 3000 kg/MW using fission, ...
Source?

Um... the PDF of the paper from NASA??

93143 · Post by **93143** » Wed Jul 20, 2011 5:33 am

You didn't read very far. It drops to less than 2 kg/kW for power levels over 3 MW, and approaches 1 kg/kW at 10 MW. 500 MW is way outside the studied range...

Also, that's for a fission plant. A p-¹¹B Polywell with direct conversion has a number of advantages in terms of power-to-weight ratio.

KitemanSA · Post by **KitemanSA** » Wed Jul 20, 2011 11:25 am

WizWom wrote:
KitemanSA wrote:
WizWom wrote: So, 3000 kg/MW using fission, ...
Source?
Um... the PDF of the paper from NASA??

Uhhh, thanks?

WizWom · Post by **WizWom** » Thu Jul 21, 2011 5:42 am

93143 wrote:You didn't read very far. It drops to less than 2 kg/kW for power levels over 3 MW, and approaches 1 kg/kW at 10 MW. 500 MW is way outside the studied range...

Also, that's for a fission plant. A p-¹¹B Polywell with direct conversion has a number of advantages in terms of power-to-weight ratio.

Actually I did read the whole paper. I find a claim of 3kg/kW pretty impressive, and enough to make the point.

As for the power level: these are automated systems. If you have a need for more power than one produces, the SMART thing is modular systems, NOT a single bigger plant. Having 10 1-MW Power units is much preferable to 1 10-MW Power Unit, all other things being equal (which they never are). These systems, however, are limited by current material science, not by the power a core can deliver.

As for the direct conversion Polywell - that's not tech we have. We don't even have a prototype of the Polywell that can run continuously, let alone a rather tricky electromagnetic energy harvester for the fast alphas.

My point, though, was that Fission-electric is _possible_ for SSTO, with current technology and no radioactive exhaust.

DeltaV · Post by **DeltaV** » Thu Jul 21, 2011 6:36 pm

WizWom wrote:However, the total output of the 747-8's engines is 66500 lbf

That's the single-engine thrust. GEnx can produce about 75,000 lbf max, for a four-engine total of 300,000 lbf.

The record for one engine (GE-90) is 127,000 lbf. Subsonic, of course. The large fan produces most of the thrust.

WizWom · Post by **WizWom** » Thu Jul 21, 2011 8:03 pm

DeltaV wrote:
WizWom wrote:However, the total output of the 747-8's engines is 66500 lbf
That's the single-engine thrust. GEnx can produce about 75,000 lbf max, for a four-engine total of 300,000 lbf.

Yes, of course. I'll fix my older post.

DeltaV · Post by **DeltaV** » Wed Jul 27, 2011 2:21 am

Pulse Ejector Thrust Augmentor Concept Video

This has me thinking of arrays of small EAPEs for VTOL.

I wonder if just sealing the elliptical cylinder ends and depending on post-thrust reverse flow through the exit slot (and maybe simple flapper valves in the end caps) would suffice to get enough air into the chamber between pulses.

A similar-to-PETA entrainment of flow by rectangular "venturis" would also boost thrust from the EAPE array.

(EDIT - Fixed link to prior post. Not working right after recent T-P site upgrade.)

KitemanSA · Post by **KitemanSA** » Wed Jul 27, 2011 12:57 pm

I've often thought that such device, where the outer duct can transform into a ram jet, might be a very efficient booster for a S(+1/2)STO launch launch vehicle.

Imagine, a fly-back ring of these units surrounding the base of a RLV. The ring would add to the thrust up thru perhaps 100,000ft then fall away and return to the launch site.

The guy that is making that flying onion should consider it.

DeltaV · Post by **DeltaV** » Wed Jul 27, 2011 1:41 pm

Got Infrastructure?

Backyard. Backyard.

DeltaV · Post by **DeltaV** » Tue Aug 02, 2011 8:44 pm

Laser-triggered electrical arcs:
Features of electrical discharges in air triggered by laser
(Edit) XX- High-voltage electrical discharges induced by an ultrashort-pulse UV laser system -XX (Edit)
(Edit -- Gone behind a paywall. Bummer. One of the pictures showed a very straight, laser-triggered HV discharge over an EAPE-relevant distance when the laser was focused near mid-gap.)
High-voltage electrical discharges induced by an ultrashort-pulse UV laser system
Ultraviolet Laser Induced Ignition Using Resonant Enhanced Mulitphoton Ionization

Electrical arcs in reverse-flow vortices (bottom of page):
(Edit) XX- Drexel Plasma Institute -XX (Edit)
http://www.plasmainstitute.org/publications/
(Edit -- Fixed dead link.)

DeltaV · Post by **DeltaV** » Tue Mar 13, 2012 5:15 pm

Apparently, high voltage discharges can produce hard x-rays, and in some cases, gamma rays.

Some new research from Japan about suppressing hard x-rays by quenching "runaway" electrons with laser pulses:
Quench of electron runaway in positive high-voltage-impulse discharges in air by laser filaments

DeltaV · Post by **DeltaV** » Thu May 03, 2012 5:03 am

Arrghh! Suppressed paper, gone behind a paywall.

http://www.opticsinfobase.org/ol/abstra ... -37-6-1130

DeltaV · Post by **DeltaV** » Sat Aug 25, 2012 5:34 am

A 10kV electrostatic motor:
http://www.douglas-self.com/MUSEUM/POWE ... motors.htm

paperburn1 · Post by **paperburn1** » Tue Oct 02, 2012 1:52 pm

DeltaV wrote:For now, I'd be happy with access to and from LEO. The zero g will help my back. In case I spot a nice island from orbit, I'd want to be able to visit it without needing an Act of Congress. Refueling needs won't be a concern with Polywell, at least for trips of a week or less. Regarding hyperdrive, I can do without that for now. Who needs the hassle of Klingons, Romulans, Ferengi, Wraith, Replicators, Orai, 14 ft tall silicon-based insects with molecular acid blood, etc. Maybe later, if I get bored.

GREEN Orion slave girls????

DeltaV · Post by **DeltaV** » Tue Oct 02, 2012 3:16 pm

The green rubs off. It's just a ploy to get more free money from the galactic government.