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Comment: Re:Subject bait (Score 4, Interesting) 237

by wagnerrp (#47439119) Attached to: A Skeptical View of Israel's Iron Dome Rocket Defense System

Stay on topic and discuss the technical aspects of the missile system, at least that is what should be discussed here.

The article itself hardly touches on the technical merits of the missile system. It mentions how there are hardly any public releases of technical aspect to discuss, and that the handful of images of the system in operation show intercept angles that are highly unlikely to be successful. The core argument of the article is that the whole situation is nothing more than a PR campaign on both sides.

Hamas fires inaccurate artillery rockets, unlikely to actually hit anything, at Israel, under the hopes Israel counter-attacks and causes lots of collateral damage that looks bad to international press.

Israel produces a defense system and makes precision counter-attacks to prove their technological and military prowess, and restraint in its use, to international press.

Comment: Re:Dual or quadricopters (Score 1) 103

Because they don't scale up.

http://en.wikipedia.org/wiki/Square-cube_law

Smaller rotors means lower mass flow rate, requiring higher flow velocity to produce the necessary thrust. Higher flow velocity means higher power requirements. The larger your aircraft, the more difficult it becomes to produce the necessary amount of power to remain airborne.

Comment: Re:Those rotor blades have no air to move! (Score 1) 104

by wagnerrp (#47404759) Attached to: ESA Shows Off Quadcopter Landing Concept For Mars Rovers
You're going the complete wrong direction. If you want to have any change in hell of actually having enough power to get this thing in the air, you need to get your blade loading down, and that means a huge rotor. Huge rotors mean you need to be running low RPMs to keep it subsonic at the tip, and remember that the colder and higher molecular weight atmosphere means the speed of sound is going to be ~30% lower.

Comment: Re:Why a separate rover? (Score 1) 104

by wagnerrp (#47404711) Attached to: ESA Shows Off Quadcopter Landing Concept For Mars Rovers
The quadrotor design paradigm exists because small electric motors are cheap, and the power-to-weight ratios available in the couple pound range are absurd to the point that good engineering is unnecessary. In the couple thousand pound range, power becomes far more scarce, and the small, inefficient rotors just won't cut it. They have lowered the minimum barrier to entry for hobbyists, and research projects that need a simple airborne platform. They don't work well for full scale aircraft.

Comment: Re: Incoming international flights (Score 1) 685

by wagnerrp (#47401771) Attached to: TSA Prohibits Taking Discharged Electronic Devices Onto Planes
Since you don't seem to be getting bored of yourself, it's the fundamental principle of thermionic emission.

Hey what is the terminal voltage of a discharged Liion battery? Of a LiPO?

Zero. In a multi-cell Li-Ion battery, once your cell voltage drops below a certain critical value, a protection circuit disconnects it from the rest of the pack. A fully discharged battery will simply be a short circuit bypassing all the individual cells.

Comment: Re: Failsafe? (Score 1) 464

Catastrophic failures can happen. There's no way to predict all eventualities, and trying to do so will bankrupt you. All you can do is provide enough redundancy to bring your statistical failure rate to an acceptable level.

Flight 232 was simply a poor design. The three hydraulic systems all had lines that ran right next to each other, and had no shut off valves. When the tail engine had an uncontained failure, it severed lines on all three systems, which then depressurized throughout the aircraft.

Comment: Re:It'll come down to an opinion (Score 1) 255

by wagnerrp (#47377969) Attached to: Austrian Tor Exit Node Operator Found Guilty As an Accomplice

It'll come down to an opinion as to whether or not the use of Tor implies an intent to allow others to break the law. While an anonymizer service itself can be used for both legal and illegal purposes

I was under the impression TOR was explicitly designed to allow others to break the law, for the benefit of regions where things like expressing an opinion is illegal. Of course an anonymizer service is only effective if there is plenty of other innocuous white noise on the same channel.

The first Rotarian was the first man to call John the Baptist "Jack." -- H.L. Mencken

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