David Fitzpatrick The Pentagon should couple a blended-wing body with advanced engines to create a new standard for transport aircraft.
David Fitzpatrick
Boeing’s C-17 was designed in a time of unfettered access to U.S. bases around the globe. Credit: U.S. Air Force
In late 1944, the U.S. military issued bid requests for a new, fast bomber with capabilities beyond the Boeing B-29. It was a time of strategic and technological change: the end of World War II, increased advances in jet technology, revelations about German research on swept-wing aircraft and increased tensions with the Soviet Union. Industry responded with the radical new design of the Boeing B-47, featuring a swept wing and jet engines mounted below the wing on struts.
The production of more than 2,000 B-47s, and their many years of service, established a “meta-configuration” for subsonic jet aircraft. Followed closely by Boeing’s B-52, 707 and KC-135 and the Douglas DC-8, the majority of large jet aircraft built since World War II have drawn on B-47 design fundamentals. As historians recognize, the B-47 story shows how military procurement can deliver step-function advancements with positive impacts beyond defense.
Another such moment may be at hand. Three long-term trends are converging to demand and enable a breakout moment in next-generation air transport development. We should seize the opportunity and use strategic Defense Department investment to design a new airlifter.
First, the pursuit of more efficient flight and the push to reduce carbon emissions may be pointing to the limits of the B-47-inspired meta-configuration. Emerging engine technologies such as open fans seem to demand alternate placement on airframes. Some concepts for hydrogen fuel (hydrogen tanks that occupy huge portions of tradition fuselage designs) seem economically impractical. Meanwhile, the new Northrop Grumman B-21 is demonstrating the blended-wing-body (BWB) airframe performance advantages in lift-to-drag ratio and structural efficiency.
The second issue is the dire state of U.S. military air mobility assets. The airlifter fleet has long been under pressure due to extraordinary demands on a fleet that is too small. In Afghanistan, for example, the Civil Reserve Air Fleet was activated. The Boeing C-17 and Lockheed Martin C-5 were designed (more than 30 and 50 years ago, respectively) for an era of largely unfettered U.S. access to routes and refueling bases. Both require stops or aerial refueling to complete long-range missions, adding complexity, cost and now vulnerability to the logistics system that we can no longer tolerate.
Third, rising tensions with China threaten access throughout the western Pacific. China’s steady advances in anti-access/area-denial capabilities could disrupt many of the traditional air mobility routes on which the U.S. relies to support its allies, even short of a hot conflict. China’s recent move to develop a new base in Kiribati—south of Hawaii and thousands of miles east of Guam—appears to confirm that intent.
So let us take advantage of this era’s swirl of technological advances and strategic challenges to launch the development of a new generation of airlifters based on blended-wing-body airframe concepts, coupled with the latest engine technologies. In particular, let’s begin replacement of the C-17 fleet with an aircraft that can meet all C-17 mission requirements but has one new strategic capability enabled by the BWB/advanced-engine combination: vastly expanded unrefueled range to at least 9,500 mi.
Imagine a BWB/advanced-engine C-17 replacement aircraft. It is large, with four open-fan engines mounted on top of the airframe, positioned for cruise and high-lift performance. The payload weight and cubic volume of the C-17 is easily accommodated. Extended range comes gracefully from the superior aerodynamics and improved ratio of internal volume-to-airframe surface intrinsic to BWB configurations. Altogether, this gives us a transformational airlifter that can make it from Dallas to Sydney without a tanker.
This is a practical, near-term objective. Based on public reports of Boeing’s BWB subscale flight model tests (X-48C) and recent engine advancements, the essentials of the concept are well established. A BWB/advanced-engine airlifter can be developed and fielded now with traditional fuels. If hydrogen technology advances, the airframe/engine concept can nimbly accommodate a transition to that fuel. Interestingly, Airbus has already begun to move in this direction by including a BWB configuration in its ZEROe hydrogen concept aircraft program.
Money should not be a problem—investment in such a program combines broad environmental advantages with defense needs. The Defense Department can provide the vision and sense of urgency. The system specification should begin with the C-17 requirements document, add improved range and translate to a BWB design. Such a program should reach preliminary design review in three years and fly near-production prototypes in 5-7 years.
The platform would transform U.S. air mobility and set the standard for eco-responsible, cost-effective military and commercial transport aircraft for decades. It’s a noble objective at reasonable risk and the sort of challenge Elon Musk would take on. Let’s find leaders who again will use strategic defense investment to build a brighter future for aerospace and the environment.
David Fitzpatrick is a 40-year veteran of the aerospace industry.
The views expressed are not necessarily those of Aviation Week.
