The Revolutionary Jet That Changed Everything: The Martin XB-48 and Its Bizarre Bicycle-Style Landing Gear

In the years following World War II, the world of aviation stood on the verge of a revolution. The introduction of jet propulsion transformed aircraft capabilities nearly overnight, propelling designers into uncharted territory. Among the myriad daring prototypes of this era, none captured both the imagination and the bewilderment of engineers like the Martin XB-48. This experimental bomber, developed in the late 1940s, didn’t just showcase cutting-edge jet power—it upended the very rules of what a heavy aircraft could be. At the heart of its most audacious features was a strange solution to a unique problem: “bicycle-style” landing gear aligned down the center, with tiny outrigger wheels on the wings. The XB-48 was daring, difficult, and deeply influential, and the story behind its peculiar gear setup is a study in out-of-the-box thinking and nerve-wracking test flights.

The Race to Jet Bombers

By 1944, America’s airpower visionaries knew that jets would soon rule the skies. The U.S. Army Air Forces launched a competition for a new, fully jet-powered medium bomber—fast, sleek, and able to deliver a heavy payload deep into enemy territory. Among the entrants were engineering giants such as Boeing, North American, and Martin. Each company brought its boldest ideas. While Boeing’s B-47 Stratojet would eventually claim victory, Martin’s XB-48 built a legacy all its own during its brief and tumultuous test career.

The Challenge: Wings Too Thin for Standard Wheels

With jet engines offering so much more power than piston engines, designers could suddenly create aircraft with much thinner wings, greatly reducing drag and enabling higher speeds. But these thin wings posed a paradox: there was now little room inside them to house the sturdy, wide-set landing gear that traditional bombers relied on. On a typical bomber like the B-17 or B-29, main wheels retracted directly into the thick lower wings, providing a stable “track” for the aircraft to taxi, takeoff, and land.

The Martin design team, led by tireless chief engineer Peyton Magruder, found themselves confronting this fundamental conflict: the wings of the XB-48, as dictated by jet-age aerodynamics, were simply too thin to fit any conventional landing gear. Yet the aircraft, a massive, six-jet, swept-wing behemoth, still needed to operate from standard runways and withstand the pounding of a heavy bomber’s landings.

Enter the “Bicycle Gear”: A Radical Gamble

Martin’s team took a leap few others would dare: why not put the major wheels in a straight line along the fuselage? Thus was born the “bicycle” landing gear arrangement—one set of main wheels just behind the nose, and one further back, both retracting into the central belly.

But such a setup raised its own fears. Without gear under the wings, the bomber would be as precariously balanced on the ground as a real bicycle. A sudden gust of wind, an uneven runway, or a turn made too abruptly could send the multi-ton aircraft tipping sideways onto the tarmac.

To prevent this, Martin added what they called “outriggers”—small, spindly wheels at the ends of short struts, mounted in the wings themselves. These outrigger stabilizers weren’t meant to bear the full weight of the aircraft, but rather to keep it upright while taxiing, taking off, or landing, much like a child’s training wheels. These odd little supports were not only crucial: they were a visible symbol of the XB-48’s experimental daring.

How the Bicycle Gear Worked—and Didn’t

The concept demanded precise choreography from both pilots and ground crews. On landing approach, the pilot would lower the main gear and the outriggers in sequence, watching carefully to ensure every wheel locked into place. Touchdown itself required a gentle hand; any aggressive maneuvers could spell disaster by overloading the tiny wing wheels or tipping the bomber off its narrow balance line.

Taxiing was just as treacherous. Test pilots described how the XB-48 had to be treated “like balancing a school bus on a tightrope,” with sudden wind gusts threatening to tip the bomber onto a wingtip. At times, ground handlers would have to brace the aircraft until the outriggers were fully deployed. One test engineer quipped that “every routine taxi felt like a circus act—everyone held their breath until it stopped moving.”

Holding Their Breath: Test Pilots and Unexpected Thrills

For the men flying the XB-48, every landing was a white-knuckle experience unlike anything they’d learned in conventional aircraft. Even veteran bomber pilots found themselves gripping the controls a little tighter on final approach. The slightest crosswind or misjudged turn on landing rollout could cause the nose to yaw or the wings to drop, pushing the outrigger wheels to their limits.

There were several tense moments in early tests—one near incident at Muroc Army Airfield (now Edwards Air Force Base) nearly saw the XB-48 tip dangerously while taxiing in a strong crosswind. Quick-thinking ground crew leapt into action, using ropes and sheer determination to keep the prototype upright until chocks could be set.

Still, the gear generally worked as intended, allowing the XB-48 to achieve 23 test flights between 1947 and 1948. The lessons learned, both about the challenges and the possibilities of thin-winged jet bombers, proved invaluable to the entire American aviation community.

The Untold Legacy

While the XB-48 never entered production (the Boeing B-47’s superior performance claimed the prize), Martin’s “bicycle” landing gear lived on in the design world. Boeing itself adopted the same arrangement for its B-47—albeit with improvements—embracing outrigger wheels for exactly the same reason. Even the legendary B-52 Stratofortress, which would define U.S. airpower for decades, owes its basic undercarriage layout to daring experimental aircraft like Martin’s XB-48.

The XB-48 also forced engineers to confront a broader truth: that breakthroughs in one area (aerodynamics) would increasingly drive radical innovations in others (landing gear, handling, safety systems). Sometimes, the wildest solutions are the ones that become the new standard.

The Human Side: Innovation, Anxiety, and Airline-Style Progress

The XB-48’s story is not merely about a curious landing gear; it’s a parable of the jet age’s leap into the unknown. At Martin, engineers agonized over the risks, but pressed forward out of necessity and hope. Test pilots, forever balancing innovation and survival, became the unsung heroes balancing a machine as strange and revolutionary as anything the postwar world had seen.

Aviation history tends to recall only the winners. But the XB-48, with its “bicycle” gear and nervy test flights, deserves special recognition: for breathtaking ingenuity, for accelerating the pace of jet bomber development, and for proving that, in a world changing faster than ever, sometimes you really do have to reinvent the wheel—one outrigger at a time.

With every touchdown, the XB-48 defied gravity, convention, and its own limits, leaving a legacy on which jet aviation still rides today.