A Martin Mars is shown in this image made with a fish-eye lens Monday at the Experimental Aircraft Association's seaplane base during the annual AirVenture. The plane is the largest flying boat ever flown operationally, with a height of 38 feet, a length of 120 feet, and a wingspan of 200 feet. Credit: Mark Hoffman

By of the

Oshkosh — Wayne Coulson has heard the urban legend and no, it's never happened to his plane.

The "Hawaii Mars" is the world's largest flying water bomber and the biggest American warbird, a veteran that's logged countless hours dropping gallons of water on blazes in several countries, saving homes and lives.

But the urban myth of a scuba diver somehow ending up in the middle of a burned-out forest — allegedly scooped by an aerial tanker loading water to drop on a fire — well, it's just that, a myth.

"I've heard it many times," said Coulson, owner of Coulson Flying Tankers of British Columbia. "A scuba diver would have to be awful thin because we have two 8-inch scoops" to suck in water.

The Hawaii Mars is visiting EAA AirVenture for the first time and drawing huge crowds eager to glimpse the massive flying boat anchored in a Lake Winnebago bay next to the seaplane base. With a wingspan roughly the equivalent of a Boeing 747, the Hawaii Mars casts a big shadow.

Only seven of the gigantic Martin Mars aircraft were built and two are still flying, including the Hawaii Mars, which is being retired as a firefighter and put up for sale. While Coulson politely declined to reveal the asking price, he did say EAA AirVenture is a good place to find a buyer because of the tens of thousands of aviation enthusiasts who come to Oshkosh for the weeklong convention that began Monday.

Originally built as long-haul Navy troop and cargo transports flying between Hawaii and the U.S., some of the Mars aircraft were converted into forest firefighting aircraft in the early 1960s. The Hawaii Mars fought fires in Canada, where it's based, as well as the U.S. and Mexico. Its most recent action was in British Columbia last summer where it flew 40 hours and made 65 drops.

The plane requires at least a three-mile-long water body and a minimum depth of 10 feet. When Coulson Water Tankers decided to come to Oshkosh it meant mapping the depth of relatively shallow Lake Winnebago and finding a spot where it can land, take off, moor and scoop up 7,200 gallons of water in its massive tanks. It's performing during the afternoon air show on Wednesday, Friday and Saturday and scheduled to demonstrate its water dropping capabilities.

"When we flew in 2009 in southern California fighting forest fires, we operated out of the ocean. When you start looking there's actually a lot of places we can work from and there's a lot of water in British Columbia so we've never had a problem," Coulson said.

The Hawaii Mars arrived in Oshkosh on Saturday, and on the first day of AirVenture Monday a steady stream of visitors to the seaplane base near Wittman Regional Airport stood at the edge of the water to snap photos.

Some purchased $125 tour tickets to take a launch to the Hawaii Mars and walk around inside the massive flying boat. Boaters drew near for a closer look and floatplanes landing at the seaplane base motored around the Hawaii Mars like gnats buzzing around a giant swan painted red and white with four engines hanging from its wings.

Special logistics

Each year roughly 100 to 150 seaplanes come to AirVenture, but none as big as the Hawaii Mars. EAA officials spent a day measuring water depths near the seaplane base to map the lake for the Hawaii Mars arrival and obtained a Department of Natural Resources permit for a 6-ton anchor that required a crane on a barge to put in place, said Paul Seehafer, AirVenture Sea Plane Base chairman.

"It was a big effort, but it was certainly worth the effort," Seehafer said. "I've been a seaplane pilot for 40 years, and to have that seaplane sitting out there has been a lifelong goal. I've been trying to get it here for the last 10 years."

Flying in the Hawaii Mars is very noisy because all soundproofing has been removed and the plane stripped down to its essentials — water tanks and cockpit.

The four-person crew includes two pilots and two flight engineers. When water is being scooped and dropped, the flight engineers take control of the plane as it travels 70 mph sucking up a ton of water each second, said Pat Floyd, general counsel for Coulson, as he guided tours on Monday. It takes only a couple of minutes to load up with a combination of water and firefighting gel and then head back to flaming forests where a typical load covers 4 acres.

"It's a frigate-sized boat. It's not bumpy bouncing along a lake at 70 mph, but it sure is noisy," said Floyd, pointing to the mix of modern and World War II-era avionics in the cockpit. "You can tell by the ignition switches. Anything that's not square is World War II."

When Andy Anderman saw a picture of the Hawaii Mars in the AirVenture program on Monday he came to the seaplane base to ask one question — was this the Hawaii Mars that flew in the late '40s and early '50s? It was.

The 72-year-old Vietnam helicopter pilot from Florida smiled. He flew on the Hawaii Mars as a youngster when his father, a chief petty officer on submarines, was transferred from Hawaii to California. He doesn't remember how old he was, but judging by the height of the hand he held out for his size on that trip, Anderman was probably 6 or 7.

The trip was "long, noisy. They told me I could go up to the navigation bubble and look out, but then I was told no. Then we found out we were running low on fuel because the California coast was fogged in," said Anderman, a longtime EAA member who flew UH-1 helicopters in the Army from 1964 to 1968.

"We landed on an inland lake and waited for what seemed like a couple of hours for a tender," said Anderman, as he gazed at the Hawaii Mars. "To see it on the water again is great."

EAA AirVenture runs through Sunday. The Hawaii Mars is scheduled to leave Oshkosh Monday.