Boeing’s unconventional X-32 prototype was not adopted by the Pentagon—but would go on to influence multiple aspects of other warplanes.
When the United States military was seeking a versatile, cost-effective fighter jet that could replace a range of aging fourth-generation warplanes, including the F-16 Fighting Falcon, the F/A-18 Hornet, and AV-8B Harrier II, both Boeing and Lockheed Martin submitted proposals for possible replacements. Boeing’s entry, the X-32, aimed to distinguish itself through affordability and simplicity.
But the X-32 was a radical departure from traditional fighter jets, reflecting Boeing’s strategy to prioritize low manufacturing and lifecycle costs. At its core was a large, one-piece carbon fiber composite delta wing with a 55-degree leading-edge sweep that could hold up to 20,000 pounds of fuel. This thick, high-sweep wing reduced transonic drag while accommodating stealth-enhancing conformal antennas—though it posed fabrication challenges.
The Specs of the X-32
One of the things was that the plane was meant to be used by both the United States Air Force and Navy. Accordingly, two variants had to be constructed. The X-32A was a conventional takeoff and landing (CTOL) warplane, pitched to the Air Force as a possible fifth-generation warplane. The X-32B, pitched to the Navy, would be a short takeoff and vertical landing (STOVL) craft.
To meet this STOVL requirement, Boeing opted for a direct-lift thrust vectoring system, positioning the Pratt & Whitney JSF119-614 engine directly behind the cockpit. This unconventional placement shifted the plane’s center of gravity forward, enabling a neutral-altitude hover—but necessitating a massive chin-mounted air intake to supply sufficient airflow during vertical operations. The result was a highly unusual aircraft that, from certain angles, resembled a grinning hippopotamus. Hence, its nickname the “Flying Hippo.”
The X-32A took to the skies on its maiden flight on September 18, 2000, from Boeing’s Palmdale facility at Edwards Air Force Base, completing 66 flights in four months. These tests showcased the aircraft’s handling qualities, including inflight refueling, weapons bay operations, and a top speed of Mach 1.6.
A year later, on March 28, the X-32B had its maiden flight. Indeed, this variant conducted 78 test flights, including a transcontinental journey to Naval Air Station Patuxent River.
Test pilots loved the X-32’s handling, and Boeing touted its potential for rapid production. But the design faced serious hurdles. Eight months into construction, for instance, the Navy refined their variant’s maneuverability and payload requirements, rendering the delta wing-shape of the plane inadequate. Boeing’s engineers devised a lighter, more agile conventional tail design for production models, but it was too late to modify the prototypes.
Ultimately, the X-32s STOVL performance left much to be desired. It went up against Lockheed’s X-35 prototype, which was viewed as more agile and versatile. The X-35 won over evaluators judging the two planes. On October 26, 2001, Lockheed Martin secured the contract for the Joint Strike Fighter (JSF), and the X-35 became the F-35 Lightning II.
Remembering the Smiling Hippo’s Influence
Still, the Smiling Hippo was not a total failure. It would go on to influence multiple aspects of other warplanes. For example, the X-32’s radar evolved into the Raytheon AN/APG-79, now a cornerstone of the F/A-18E/F Super Hornet and EA-18G Growler. The program also helped Boeing improve at stealth technology development and cost-effective manufacturing, influencing later projects like the X-45A Unmanned Combat Air Vehicle (UCAV).
The “Smiling Hippo” had a distinctive design and some real innovative elements to it. Today, the Lockheed F-35 may dominate the skies, but the X-32 remains a fascinating footnote. And while Lockheed won the day over Boeing with the F-35, Boeing appears to have gotten the last laugh—with the Trump administration’s decision last week to go with Boeing over Lockheed to develop the sixth-generation warplane.
Perhaps the Smiling Hippo can smile once more at the thought of its cousin, the F-47, beating out the Lockheed Martin engineers for developing the next-generation warplane.
About the Author: Brandon J. Weichert
Brandon J. Weichert, a Senior National Security Editor at The National Interest as well as a contributor at Popular Mechanics, who consults regularly with various government institutions and private organizations on geopolitical issues. Weichert’s writings have appeared in multiple publications, including the Washington Times, National Review, The American Spectator, MSN, the Asia Times, and countless others. His books include Winning Space: How America Remains a Superpower, Biohacked: China’s Race to Control Life, and The Shadow War: Iran’s Quest for Supremacy. His newest book, A Disaster of Our Own Making: How the West Lost Ukraine is available for purchase wherever books are sold. He can be followed via Twitter @WeTheBrandon.
Image: Wikimedia Commons.
