The Edwards Diaries
Test pilot Glen Edwards kept book on the Flying Wing. Now we know what he thought of the airplane he died in.
- By Daniel Ford
- Air & Space magazine, July 1997
(Page 2 of 5)
By 1941 German troops occupied most of Europe's capitals and appeared ready to capture London and Moscow next. Fearing it might have to fight a transatlantic war, the U.S. Army wanted a super-bomber that could carry 10,000 pounds of bombs to Germany from North America. Northrop built the B-35, a Flying Wing, while Consolidated Aircraft developed the B-36, conventional in every respect but its size (see "B-36: Bomber at the Crossroads," Apr./May 1996).
Even the Wing was huge by the standards of the day: It spanned 172 feet, weighed 100 tons, and developed 12,000 horsepower from four huge engines. It was such a giant leap from the N-1M that the Army also agreed to fund an intermediate version. One-third the size of the big bomber, the N-9M was supposed to be aerodynamically identical. So it was a bad omen when the first one was delivered late, cost more than budgeted, rattled and shook, failed to deliver the promised range, and then crashed, killing its pilot.
Lacking a fuselage and tail, a Flying Wing can rotate easily around its lateral axis--the imaginary line running spanwise through the wings--and even Jack Northrop fretted that his design might be inherently unstable. While he was experimenting with moving the N-9M's center of gravity forward and aft, the test pilot apparently let the nose point so high that the wing stalled.
Now, if you stall a Cessna, you can release back pressure on the control stick and the airplane will drop its nose naturally and resume flying. A Flying Wing is not so polite. In the N-9M and other all-wing aircraft of the time, the airflow separation at the stall rendered the trailing-edge control surfaces ineffective (see "Go With the Flow," June/July 1995). Or worse, the forces on the controls reversed, slamming the control stick into the pilot. The Wing might go into a tail slide, flip over backwards, or fall off to one side in a spin.
In time, the team of Northrop, von Karman, and Sears tamed the N-9M, but the Army was losing patience with the development problems at Northrop and Consolidated. Development of the B-36 was behind schedule, and the XB-35, which was even more of an engineering challenge, had yet to fly. So the production contract was canceled, leaving only two X (experimental) and 13 Y (service test) B-35s on order.
The XB-35 finally took to the air in June 1946, almost a year after Japan had surrendered. Company pilot Max Stanley flew it to Muroc Army Air Base. "No trouble," he reported. The same couldn't be said of the XB-35 thereafter: Its engines overheated, its propeller shafts vibrated, its propeller gearbox broke down, and its auxiliary power unit (a gasoline-powered electrical generator) failed. In the end, the X models would manage to fly for a total of 36 hours, for an amortized cost of $1.8 million per hour.
It didn't matter, because the Army had already decided to adapt its super-bombers to jet propulsion. Consolidated (now called Convair) would hang four turbojets on its B-36, outboard of its piston engines. Northrop's Flying Wing would get an even more radical makeover, its engines replaced by eight turbojets, along with a new designation: the B-49. Because the airframe had proved airworthy, it could go straight into flight test, and with little delay: The first YB-49 was rolled out in October 1947. "Spewing a twin trail of black smoke, the sky monster swept into the air before the awed thousands gathered to witness the historic take-off," gushed a company press release. Max Stanley was again at the controls, and again it was a delivery flight to Muroc--now the property of the newly independent United States Air Force.
In theory, company pilots performed the initial flight tests on new airplanes to prove their airworthiness, then military pilots put them through acceptance tests. In fact, the Air Force's Bomber Test Branch was involved from the first day. When the second YB-49 was ready, Major Robert Cardenas flew it from the factory to Muroc. Cardenas was also the pilot on February 23, 1948, when the nosewheel door blew off the "Two" (the test pilots coined a shorthand to refer to the first two airplanes--the One and the Two). With jet engines, the Wing simply took off too fast. Thereafter, Cardenas lifted the nose as soon as the wheels left the ground, bleeding off speed until the wheels retracted. "Then you leveled off," he recalls, "and you'd sit there rocking in your seat, back and forth, in unison with the slosh of the fuel." The B-49 had no fuel-cell baffles.