6 ms·
As planes use most of their energy to not crash into the ground, I could see the most practical use of this technology for propulsion where crashing isn't a maj
by mchannon 8y ago
As planes use most of their energy to not crash into the ground, I could see the most practical use of this technology for propulsion where crashing isn't a major concern.
Airships (dirigibles/blimps), and to a lesser extent, sea and land vehicles.
- isostatic 8y ago> I could see the most practical use of this technology for propulsion where crashing isn't a major concern. Missiles jumped to mind. That's their whole purpose.
- cal5k 8y ago"We've fired the missiles, sir" "Excellent... when do they hit?" "According to our calculations... ohhh about 6 weeks from now"
- isostatic 8y agoRevenge is a dish best served cold. I was thinking how Musk could do that. Launch some tungstan rods into a highly eliptical orbit, small thruster + control pack on them to adjust their orbit when required. When it's out at say 300,000k+ fire the engine for a few seconds, adjusting the orbit so it will crash into the chosen target a few days from now. The high apogee means not a lot of power to change orbit to collision, and almost impossible to detect. It would likely appear to be an asteroid hit.
- thrill 8y agoThat would certainly raise the level of Bitcoin blackmail.
- patrickg_zill 8y agoIt's rumored that the US military has a "Rod of God" satellite. No way to confirm its existence of course.
- rripken 8y agoYou may like Heinlein's "The Moon is a Harsh Mistress".
- ben_w 8y agoI’ve looked at this idea myself. At current cost per kg to LEO launch and kW/kg solar, even if you could totally ignore reaction mass (I dunno, invent a ramscoop for van Allen belts or something), it only becomes cost competitive with dynamite after a few years.
- DuskStar 8y agoDynamite doesn't come with a delivery mechanism though, which might change the equation a little.
- Tade0 8y agoI think his guy is in that Tesla Roadster in space.
- moftz 8y agoExcept you need missiles to go much faster than ion thrusters can go. 11 mph is enough for someone to shoot down your missile with a rifle.
- jandrese 8y agoAt 11 mph they could outrun it on foot.
- dangerlibrary 8y agos/rifle/rock/
- stouset 8y agoMissiles, just like planes, still use most of their energy to not crash into the ground. The point was that this current design won’t be enough energy to keep a heavy vehicle aloft, but it could be enough to propel something that can passively stay airborne.
- godelski 8y agoI wouldn't expect to see this on passenger aircraft anytime soon. They even had to build light weight high voltage converters. There's also a lot of safety things involved when you're dealing with tens of kV (which in a big craft we're talking at lease MV). BUT these things could be used for silent drones. Think more spy type drones, not predator type drones.
- tener 8y agoThere is a lot of safety stuff with the current design of the airplanes. If this is just simpler or had fewer parts that can break, it may still be a win.
- istjohn 8y agoI'm pretty sure the voltage wouldn't need to increase for a bigger aircraft. The current would increase as you ionize more nitrogen molecules, but the voltage required to tear away the electrons doesn't change.
- brian-armstrong 8y agoA bigger plane would need to ionise larger nitrogen molecules.
- alanbernstein 8y agoThis is why jumbonium was invented.
- deleted 8y ago[deleted]
- antonvs 8y agoBad news for Airbus
- jessriedel 8y ago> As planes use most of their energy to not crash into the ground Not disputing you, but do you have a quick argument for this? My understanding is that passenger planes fly at high altitudes because at lower altitudes (higher pressures) they would expend most of their energy pushing air out of the way.
- soperj 8y agoat high altitudes there's also a lot less turbulence.
- ccozan 8y agoso why not use jets to reach cruise altitude, then switch to ion thrusters ( for which you don't need fuel )?
- fwip 8y agoIon thrusters still need "fuel" in the form of electricity from batteries. These ion thrusters have worse thrust/watt than an electric propellor drive, and far worse than the jet engines they use. So there's not really any reason to use ion thrusters at cruising altitude, unless the relative silence is worth paying a lot more per-ticket.
- taneq 8y ago> So there's not really any reason to use ion thrusters at cruising altitude, unless the relative silence is worth paying a lot more per-ticket. Even then, I'd imagine that a significant portion of the noise in an airliner is wind noise rather than engine noise. Your plane is only going to get "less noisy", not "silent". Good noise canceling earphones are a far better solution (I have some specifically for plane flights, they're awesome!)
- mrfusion 8y agoPotentially lower maintenance costs with no moving parts. Plus potentially cheaper to manufacture.
- schiffern 8y ago>planes use most of their energy to not crash into the ground Surprisingly, not by much! To the first approximation an optimized plane will use 50% of its power during cruise generating lift ("not crashing into the ground"), and 50% of its power overcoming drag.[1] The tie is broken because planes expend extra more energy climbing than they save descending, and that's also part of "not crashing into the ground." :) [1] http://www.withouthotair.com/cC/page_272.shtml http://www.withouthotair.com/cC/page_272.shtml
- albertgoeswoof 8y agoThis engine will struggle at high altitudes because there’s less air molecules to ionise
- FlyMoreRockets 8y agoMaybe. At high altitudes, the ions can be accelerated to much higher velocities before losing energy due to molecular collisions. Higher acceleration of the working fluid, more thrust and higher efficiencies. Much like a rocket. There is also a lot less drag on the rest of the vehicle.
- shostack 8y agoThe sooner we get back to the age of dirigibles the better. Personally, I'm a little surprised we don't have them in the Bay Area. With our traffic and (mostly) year round nice weather, and great solar energy potential it seems like it could be a win. But then again I don't know much about the technology or it's limitations.
- yogaboll 8y agoIt's limited by the fact that you need a very large volume of lighter-than-air gas to lift a human. The theoretical maximum lift capability of 1 m^3 of hydrogen is just about 1.1 kg so you will need a really big airship to carry a passenger.
- grondilu 8y agoAren't most planes capable of gliding well enough to land?