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28-09-2006, 09:57
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מומחה לתעופה, תעופה צבאית, חלל ולווינות. חוקר בכיר במכון פישר
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חבר מתאריך: 02.07.05
הודעות: 11,672
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הצעת מפעל מל"מ של התעשייה האווירית:
http://www.iai.co.il/Events.aspx?do...8&lang=EN&pos=5
וכתבה שפורסמה בשנת 2004 בעיתון Space News:
A division of Israel Aircraft Industries Ltd. (IAI) specializing in missiles and command and control systems is promoting a new stratospheric airship concept that advocates say could give the firm’s satellite division a run for its money.
Proponents of the IAI MLM Division’s Solar Powered Airship (SPA) concept say the helium-filled stratospheric platform may become a cost-effective alternative to satellites for applications including remote sensing and communications.
As currently envisioned, the SPA could hover in a fixed position some 21 kilometers above Earth or fly from region to region according to immediate demand. It could cover a ground area of 1,000 kilometers in diameter.
The 20-ton, 190-meter-long SPA could carry payloads of up to 1,800 kilograms, enough to accommodate huge high-resolution telescopes, along with an array of other sensors, and electronic-warfare, target-tracking and communications packages.
Powered by solar cells during daylight hours and regenerative fuel cells at night, the SPA is expected to operate continuously for about three years, nearly two-thirds the operational lifespan of most low Earth-orbiting satellites. Unlike satellites, however, the SPA will not require expensive and risky rocket launches, SPA enthusiasts said.
"This concept combines the very best attributes of geostationary and low-Earth orbiting satellites. … And no satellite can be brought back to Earth for service, repairs, upgrades or payload changes," said Abraham Baum, research and development manager of IAI’s MLM Division.
The airship would rely on laws of buoyancy for lift, carry its own navigation, guidance and control system, and be equipped with a rear propeller, tail wings and aft stabilizer. It will be encased in multiple leak-proof, adhesive layers constructed from strengthened, sun-resistant materials.
Powered by an array of solar cells at the top of the platform, the SPA would have its own energy-conversion, storage and distribution system co-located with the payload and navigation system at the bottom of the airship.
Baum said the SPA would be able to hover and maneuver in winds reaching speeds of 40 to 50 knots.
For remote sensing missions, Baum said, the SPA could easily trump spy satellites because it could house a combination of large telescopes, synthetic aperture radar and other information collection systems. "Since we can house huge telescopes, our resolution [for remote sensing applications] can be measured in centimeters," Baum said in a late January interview.
For telecommunications services, Baum said, the SPA has an advantage over geostationary satellites, since the lower-flying airship could transmit signals without the second or so delay, known as latency, that is characteristic of satellite communications. "There’s invariably a delay with geostationary satellites. But since we’re closer, there will be no delays," Baum said.
He added, in reference to the Amos 1 and Amos 2 telecommunications satellites built by IAI’s MBT Division, "SPA’s payload capacity can translate into the equivalent of nearly 10 Amos satellites."
Israel’s Ministry of Defense is supporting the SPA concept in principle, primarily for early warning and missile defense missions. In recent months, the concept has been the subject of briefings by the Defense Ministry’s Research and Development Directorate to the U.S. Missile Defense Agency, which has embarked on a similar program called High Altitude Airship.
"It’s a very interesting concept to be able to have a self-sustained system flying two times as high as air traffic anywhere over the Mediterranean for extended periods that would provide critical information pertaining to missile defense," said Arieh Herzog, director of the Israel Missile Defense Organization.
According to Herzog, Israel’s Defense Ministry is particularly interested in the SPA’s ability to loiter over areas of interest for extended periods, a capability that low Earth orbiting satellites do not have. "We won’t have to worry about a revisit time, and the imagery and data should be much better than that collected by satellites flying at much higher altitudes," Herzog said.
Herzog, Baum and other SPA supporters acknowledge that the concept has a long way to go before it reaches fruition due to relatively high developmental costs. Baum estimated that it would cost about $100 million to develop an operating prototype; with production versions expected to cost $20 million to $30 million. With requisite funding, Baum said it would take less than four years for IAI to deliver an operating prototype.
Meanwhile, IAI’s MLM division and supporters within Israel’s Defense Ministry are seeking strategic investors for the program. Although the Pentagon’s Missile Defense Agency is the first choice for such a cooperative development, Baum said his division also is pursuing potential partners in Europe and in Asia.
"We realize we need to go to governments for this type of funding, and that the initial focus of SPA will be for military and governmental missions. But down the road, the spin-off potential for the commercial market is enormous. We’re convinced that whoever chooses to enter this field will make money," Baum said.
He added, "We are convinced the SPA is the platform of the future. For the cost of a single satellite, the SPA can provide so much more capability."
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