A few historical flights of fancy

NASA's X-43A test plane took its first unpiloted flight last Saturday. Designers had hoped the plane - powered by a "scramjet" - would fly seven to 10 times faster than the speed of sound. That's 7,200 miles per hour. Instead, the plane developed serious problems and had to be destroyed in flight. Now designers will study what went wrong and what they need to change before the next test.

"We'll keep pressing on," says NASA spokesman Chris Rink. "That's why it's an experimental plane."

Notice the "X" in the X-43A's name. It means "experimental." And that can mean surprises. NASA has a number of X planes in the works, but the X-33 is no longer among them. This wedge-shaped, self-contained space shuttle was canceled after almost $1 billion had been spent to develop it. There were just too many technical delays and costs.

"X-vehicle programs are about taking risks and pushing the envelope," says Gene Austin, X-33 program manager for Marshall Flight Center in Huntsville, Ala. "That is how we break through barriers that previously held us back." Sometimes the experiments work, sometimes they don't. But learning from your mistakes is part of the process.

Aviation has come a long way since Orville and Wilbur Wright made their first powered flight at Kitty Hawk, N.C., on Dec. 17, 1903. Before that, the Wrights had made more than 1,000 test flights with gliders for more than three years. They had learned, step by step, which wing designs offered the best lifting power and control. They traveled far from their hometown of Dayton, Ohio, to find a suitable test site. They selected Kill Devil Hill, near Kitty Hawk, on the advice of the United States Weather Bureau. It is a narrow strip of sand with favorable winds.

Between the Wrights' first powered flight and today, there have been many successful experimental planes - as well as many failures. But the failures all helped pave the way to success. Here are a few of the experiments that moved aviation forward, even though they didn't get very far off the ground themselves.

The houseboat with wings

In 1920, Italian Count Caproni dreamed of building a deluxe airplane that would carry 100 passengers across the Atlantic. He started with a houseboat. To lift the 55,000-pound craft he added three sets of triple wings. The Transaereo did manage to get about 60 feet out of the water before plummeting back into the lake in a shower of splinters. No one was hurt. But people learned that it takes more to make something fly than just putting on wings.

Put it in a garage, or a hangar?

A number of companies have tried to create a combination airplane and car. One that actually got off the ground was the Convair Model 118 ConvAirCar, which flew in July 1946. Early in November 1947, however, the second model ran out of gas while in the air and was forced to make an emergency landing. The pilot was unhurt, but the ConvAirCar was damaged beyond repair.

Developers also realized that even if they put a flying car in every garage, you still had to drive to an airport to takeoff and land. So what was the point? Convair decided to drop the idea. No one has tried to make an "air car" since. It's a good idea, but not as practical as inventors had hoped.

In this model, you had to back in for a landing

Many designers have tried to invent an airplane that doesn't need a runway. They dreamed of a plane that takes off straight up and lands straight down.

Two attempts at this were the Lockheed XFV-1 and the Convair XFY-1 Pogo. The US Air Force ordered prototypes built in 1951. The planes stood on their tails for takeoff -a promising start. But pilots soon realized that landing would be tricky. They would have to look back over their shoulders as they brought the craft down. By 1955, both projects were canceled.

British Aerospace later developed the Harrier "jump jet," a successful VTOL (vertical takeoff and landing) plane. It lifts off and lands from a horizontal position, though, like a helicopter.

The wooden monster

In 1942, Nazi submarines were sinking Allied cargo ships at an alarming rate. How could weapons, troops, and supplies be ferried safely across the Atlantic? Aviation pioneer Howard Hughes proposed the HK-1 Hercules, a gigantic freight-carrying airplane. When finally completed, it was about as long as a modern Boeing 747, but with a wingspan 1-1/2 times as wide.

Aluminum was needed for the war, so the plane was made largely of birch and a little spruce. The spruce gave it a nickname Mr. Hughes hated: "The Spruce Goose." Many people thought it would never fly. Powering a plane that large with propellers was difficult, too. Eight four-bladed propellers more than 17 feet in diameter were needed. Special power-boosting methods had to be developed.

The plane finally did make it off the ground - once, in 1947, for about a minute. It had cost $25 million, and no one wanted to build more of them. But some of the lessons learned about building the plane later helped with the development of big jets like the 747.

Talk about your jet skis....

In 1951, the US Navy began to develop a jet that could land on water: the Convair XF2Y Sea Dart. The first model had vibration problems related to its two landing skis. The second had a single ski and worked better. It was the first supersonic seaplane. (USAF Capt. Charles "Chuck" Yeager had first broken the sound barrier in 1947 with the X-1 rocket plane.) As development on the Sea Dart continued, the Navy realized something: There was no good reason to land a jet on water. It made much more sense to land jets on carriers. The project was canceled by the mid-1950s. Sometimes you learn technical lessons from experimental craft. Sometimes you learn to make sure you need something before you try to develop it.

It's a car ... it's a plane ... it's weird

The ConVairCar was basically a car with an airplane on top. Other inventors had tried to develop a carplane that was mostly an airplane with sturdy wheels for the open road. None turned out to be successful.

One of the biggest problems was what to do with the wings. They could present a serious traffic hazard. One proposed solution was to take the wings off and leave them at the airport. But this meant you couldn't fly the car again until you went back to that particular airport. Another solution was to haul the wings behind the car in a trailer. You couldn't carry the trailer with you in the airplane, though. Fold-up wings were also investigated.

In the late 1940s, people thought there would soon be carplanes in every garage (or hangar). It sounded like a great idea, but the technology never really got off the ground. We may not see flying cars until we reach the future world of cartoon character George Jetson. Then again, technology can move pretty fast with the help of a few promising new engineers. If you were going to build a carplane, what would it look like?

(c) Copyright 2001. The Christian Science Monitor