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KANDIL SEEKS SOLUTION TO 'SUPER' SONIC BOOMS

Osama Kandil's invitation to deliver a paper at the International Forum on Sonic Boom July 21-22 at Penn State University was sweet reward for an aeronautical engineer who was pressed into 80-hour work weeks late last year in order to save face for the United States in a technology race with France.

"I am persistent by nature. I never give up. And now it is paying off," said Kandil, the Old Dominion University eminent scholar who formed the Department of Aerospace Engineering and was its chair from 1993-2002.

The forum will be a coming out party, so to speak, for Kandil's paper on the "super boom problem," which is a short duration "focusing" or sharp increase in a sonic boom that happens when a craft flying at supersonic speed accelerates, makes a turn or some other maneuver. At its worst, a super boom can be three times as great as a regular boom and create a shock on the ground that can kill people and topple buildings.

The story behind Kandil's paper reads like an international adventure novel.

NASA first asked him late in 2003 to submit a grant proposal aimed at solving the super boom problem by means of a theoretical/computational model. The French at that time had already published a solution. "I thought, 'Gee, how did you guys let that happen,'" Kandil said.

In 2003, proposed development of a small supersonic commercial jet had raised the stakes in the race to better understand and mitigate sonic boom. Marketing research predicts that these jets, usually envisioned as having a passenger capacity of 20-25, could be the next big thing in air travel for well-to-do travelers such as business executives. But to draw the passengers necessary to make these aircraft economically viable, the jets would have to fly at supersonic speeds over land, as well as water, allowing a New York to Los Angeles flight in less than three hours, and New York to Paris in a little over four hours. The phased-out Concorde was restricted by most countries from flying at supersonic speed over land.

Kandil and colleagues at ODU have been active in sonic boom prediction and mitigation as part of a federal Defense Advanced Research Projects Agency (DARPA) initiative to hasten development of a "quiet" supersonic business aircraft. Some ODU theoretical models developed in 2002-04 -- most notably in sonic boom prediction and wing design -- promise to help lessen the intensity of sonic boom shock waves reaching the ground from a small jet. At present, the standard boom reduction that seems possible would bring the level in line with DARPA's goal of 0.3-0.5 pounds per square foot (psf) of pressure in excess of normal atmospheric pressure. By contrast, the Concorde's conventional flight boom was 1.95 psf when it was flying at 1,350 miles per hour, which is almost twice the speed of sound.

The innovation of French engineers was a code that would allow a super boom solution to be part of an over all sonic boom mitigation scheme. Overland supersonic flight restrictions are not likely to be lifted until the super boom problem is solved.

So we move to November 2004, when NASA and Kandil finally ironed out a misunderstanding about this country's super boom project. Kandil learned then that anxiety had intensified here about the French lead in understanding super boom. He was told he must come up with a solution before the end of the year or forfeit a substantial portion of grant money from NASA.

Xudong Zheng, an ODU doctoral student, and Isik Ozcer, a master's student, both of whom are in Kandil's inner circle in sonic boom research, teamed up with their mentor for what was a suspenseful last six weeks of 2004. "We were staying in the computer lab until 3 and 4 in the morning," Kandil remembered. But nothing much had been resolved by mid-December. Zheng, who was point man in the sonic boom focusing (super boom) work, got so frustrated that he asked Kandil for permission to e-mail French engineers whose solution had been published.

"He wanted just to discuss some things. I didn't think much would come of this, but he did it. And the French answered right back. They said the work was produced with funding by Airbus and was highly confidential, and that we cannot talk with you," Kandil said.

On Dec. 27, Zheng reported that the code the ODU research team had developed was generating computer results that were off by 180 degrees. "Our results would have to be flipped to compose a solution," Kandil said. "Then we discovered a bug. We simply had a bug in the code, which I had suspected for sometime. We had missed a term in the equation. We discovered this and we had matched the French results. Our report was delivered on Dec. 28."

In fact, the ODU team had so thoroughly probed the problem that its report included four solution methods. The French had come up with just one.

"All of a sudden, NASA is very happy," Kandil said.

Just two weeks into 2005, Kandil was in Reno, Nev., for an American Institute of Aeronautics and Astronautics Aerospace Sciences Meeting. "It was a special session on Shaped Sonic Boom Predictions and Mitigation," Kandil said. "Everyone was talking about our work at ODU. NASA was saying, 'Kandil got it,' about the super boom solution." At the same meeting, results of actual flight measurements reported by Northrop-Grumman corroborated formulas that Kandil and his team had developed a year earlier to predict sonic boom. Before January was over, NASA had rewarded Kandil with its "Turning Goals into Reality" Award for outstanding contributions to sonic boom research.

NASA agreed not to publish Kandil's report until his super boom solution could have its debut at the conference this month at Penn State. Kandil smiled when he related that French engineers are among the organizers of this international forum. "I think we were invited to come because they heard about our work in Reno. They are eager to see what we have done. But they can wait."

He also will deliver another paper Aug. 15-17 at the AIAA Atmospheric Flight Mechanics Conference in San Francisco.

In the meantime, Kandil's team, which now also includes doctoral student Nitin Khasdeo, forges ahead with work related to super boom, advanced sonic boom prediction schemes and mitigation of sonic boom ground signals.

"We think the development (of the "quiet" supersonic commercial aircraft) will take 10 years," he said, "and during that time we at ODU should play a significant role in the project."

This article was posted on: July 13, 2005

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