On 12/15/11 3:41 PM, Joe Leikhim wrote:
Arriving this week, IEEE Magazine this months issue has an article about pilot-less commercial airliners, comparing the UAV drone technology as being readily available to fly paying passengers from here to there. Coincidentally the table of contents page depicts a drone which appears to be this very same "Beast of Kandahar" taking off! I look forward to the future letters column. I for one would not trust a pilot-less plane to transport me knowing that a terrorist need only to jam or spoof the GPS constellation, and bring down hundreds of planes.
Oddly enough, most airplanes do NOT use GPS as their primary navigation system. VOR/DME (or TACAN) is one. Inertial Nav is another. One of the big deals about the 747, in fact, was that it carried a high performance Inertial Nav unit allowing it to do long distance overwater flights and wind up close enough to not miss the destination airport. (Look up North Atlantic Minimum Navigational Performance Standards in the FARs). This was also one of the uses of the late lamented OMEGA system.
In fact one of the reasons for WAAS is that it provides signals to warn aircraft that the GPS signals are invalid.
Sure, GPS makes it easy to do things like JDAM strapons for bombs, but folks have been flying cruise missiles (which are basically UAVs with a warhead) with IMU and terrain comparison for decades.
Which isn't a whole lot different than a human flying a small plane by dead reckoning and pilotage.
For what it's worth, the real issue with UAVs is that they aren't very mechanically reliable. The crash rate is on the order of 1 per 500 flight hours. (compare to a F16 at around 1 per 50,000 hrs, commercial airliners are hugely more reliable.. 1 flight with at least one fatality per 5 million flights ) Fine in a battle zone or out over deserted areas, not so practical carrying passengers or doing surveillance over a city. If you flew a single UAV 24/7 you'd have a crash about once every 3 weeks.
The hard part is NOT the navigation or communication or flight controls. It's keeping the engine running.
Heck, the proposed
LightSquared system could bring the planes down.
_______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
