An aircraft stretching 108 meters in length, the largest ever, is being developed. Its passengers are extra-large blades used for wind power generation. Onshore wind turbines have not grown larger because of limits in ground transport, such as height restrictions on overpasses and a lack of paved roads, and the idea is to solve this with air transport.
Because a wind turbine's output is proportional to blade size, transporting extra-large blades by air could double the profitability of wind power, according to one outlook. The obstacle is that President Trump strongly opposes wind energy. Will the largest aircraft ever bring a gale to wind power, or fizzle out as a storm in a teacup?
◇ U.S. Radia developing with a 2030 target
Spectrum, published by the Institute of Electrical and Electronics Engineers (IEEE), the world's largest engineering society, reported on the 10th (local time) that "Radia, based in Boulder, Colorado, is developing a transport aircraft with a cargo space 12 times larger than that of the large passenger jet B747."
Radia's WindRunner under development is 108 meters long and 24 meters tall. The largest aircraft ever was the Antonov An-225 "Mriya," developed by the former Soviet Union in the 1980s to transport the Buran space shuttle. It was 84 meters long and 18 meters tall. However, the last airframe in Ukraine was destroyed by a Russian airstrike in 2022. Set to inherit Mriya's throne, the WindRunner is 49% longer than the Airbus A380-800, currently the largest aircraft.
WindRunner's cargo is blades for onshore wind power. It is designed to carry two 95-meter blades or one 105-meter blade. Aerospace engineer Mark Lundstrom came across Radia in 2016 after seeing petitions from wind turbine developers. At the time, companies distributed press releases pleading that they could produce larger onshore wind blades if only there were a way to transport them.
Large blades for offshore wind turbines can be shipped by sea. By contrast, oversized blades for onshore wind power are hard to transport over land. In the United States, the height of overpasses is limited to 4.9 meters, so large blades cannot pass. The situation is similar in Europe. Developing countries have fewer tunnels and overpasses, so that problem does not exist, but the lack of paved roads makes it impossible to haul 50-ton blades.
There are exceptions. Some regions in China have no road constraints, allowing construction of extra-large onshore wind turbines. Last year, Sany Renewable Energy, a Chinese multinational, erected a 15 MW (megawatt) wind turbine with 131-meter blades in Tongyu, Jilin Province, in the northeast. However, the blades were made in Inner Mongolia and traveled 1,800 kilometers to the final installation site. It took that much longer.
Another option is to segment large blades for transport and assemble them on-site. But the joints add weight and are weaker than single-piece blades. One could also envision using 3D printers at power plant construction sites to produce large blades, but that is still in the research stage. Ultimately, the practical solution is air transport.
◇ Unique shape tailored to transporting wind blades
Large aircraft need runways several thousand meters long to take off and land. The takeoff roll for the large passenger jet B747-400 is about 3,000 meters, and the landing roll is about 2,000 meters. That is why international airports need 4,000-meter-class runways. Radia, by contrast, said the WindRunner is designed to take off and land within 1,800 meters. This takes into account that power plant sites will struggle to host proper airports.
First, it is equipped with four jet engines for short takeoff. Radia CEO Lundstrom said, "If the WindRunner is not carrying cargo, its thrust-to-weight ratio rivals that of early fighter jets." To avoid the fuselage striking the runway when the nose is rotated up for short takeoff, the aft fuselage is angled higher than the front. To maintain stable attitude during short takeoff, the tail must also be tall. But to meet the 24-meter airport height limit, the tail was split into two.
WindRunner's landing roll is about 1,080 meters, roughly 10 times the fuselage length. The wings are short and broad, with a surface area reaching 1,000 square meters. The B747 has long, narrow wings with a surface area of only 511 square meters. Thanks to this, the WindRunner generates more drag and can decelerate quickly. The large tires used on the U.S. military's C-130 Hercules also help with braking.
The cockpit for five pilots is housed in a protruding section atop the front fuselage. Its size rivals that of a Gulfstream business jet. When the nose door opens upward, wind power blades enter along rails laid on the floor. To save energy during flight, the cargo hold is pressurized only to the level at the summit of Mount Everest.
◇ Aiming to double profitability of wind power
The reason the wind power industry is trying to enlarge turbine blades is that it can produce that much more energy. Current wind turbines generally use 70-meter blades. Radia is building a transport aircraft that can carry 105-meter blades, which are 50% longer. Michael Howland, a professor in the Department of Civil and Environmental Engineering at the Massachusetts Institute of Technology (MIT), told Spectrum, "A wind turbine's power capacity increases in proportion to the cube of wind speed and the square of the diameter of the circle swept by the rotating blades."
This means that even with an extra-large transport aircraft and enormous fuel consumption, the gains in generation capacity more than offset it. The continued growth in turbine blade size recently is for the same reason. Wind power has drawn attention as clean energy, but it has also faced criticism for bird strikes and noise. Radia CEO Lundstrom said, "With larger blades, you can halve the number of turbines and still get the same electricity."
For example, wind turbines equipped with extra-large blades can cut costs by 20%–35% while increasing output by 10%–20%. That means that even when including all transport costs, the profitability of wind power can be doubled. CEO Lundstrom said, "Smaller turbines need wind speeds of 7 meters per second to generate electricity, but larger turbines can turn at lower rotational speeds, so 5 meters per second will do," adding, "As a result, if large turbines become standard, the area where wind power is viable could double."
Of course, there are many hurdles to overcome before the "Attack on Titan" of the wind industry can be commercialized. Fluid dynamics has not fully predicted what will happen when extra-large blades spin. Some forecasts even suggest that as giant blades rotate, the Coriolis effect—which influences typhoon tracks as well as temperature depending on Earth's rotation—could change. This implies a need for basic science research.
The biggest practical obstacle is U.S. President Trump, who opposes renewable energy. The Trump administration halted approvals, permits, and government support for wind energy. Radia, however, said the winds from Washington would not clip its wings. In April, CEO Lundstrom told the New York Times, "We expect market uncertainty to abate quickly."