Bengaluru startup Alteon has raised $2.5 million to build a fixed-wing drone that stays in the air for more than a year without carrying the energy to do it. The pre-seed round was led by Lachy Groom, the San Francisco solo investor and former early Stripe employee, with Together Fund also participating. Founder Samay Sanghvi is 20 years old and started building aircraft straight out of high school in 2023.
The plan runs on dynamic soaring, the technique albatrosses use to cross oceans at almost no metabolic cost. Alteon says it will point the aircraft at maritime surveillance first, selling governments continuous visibility over their own waters.
For scale: the longest continuous flight ever recorded by an aircraft is 67 days, set in April 2025 by Zephyr, the stratospheric solar aircraft flown by Airbus subsidiary AALTO. Alteon is aiming for more than five times that, on an airframe with a wingspan of roughly 10 feet.
Dynamic Soaring Pulls Energy Out Of The Wind Gradient
Dynamic soaring extracts energy from wind shear, the layering of air moving at different speeds above the ocean surface. An aircraft dives into the slow layer near the water, turns, and climbs back into the faster layer. Each loop banks a little more energy than the maneuver costs.
Conventional aircraft carry their whole flight in a tank or a battery pack, which is why endurance and payload trade against each other so brutally. Alteon is building a small fixed-wing autonomous aircraft with a wingspan of about 10 feet (three meters) that flies close to the water, climbs and turns through faster-moving air, and repeats the cycle. Sanghvi told TechCrunch the company eventually wants to run the propellers backward as turbines, converting some of the harvested energy into electricity and pushing it back into the onboard batteries.
Sanghvi’s pitch for why this is worth doing at all is blunt. Once aircraft can stay up for more than a year, he said, “there are millions of things you can do with them”.
Alteon Has Flown The Maneuver Without Proving The Endurance
Alteon recently flew its autonomous flight system over the Bay of Bengal, completing seven O-shaped cycles at more than 62 miles per hour (100 kilometers per hour) while staying within about three feet (one meter) of the water. It has not yet sustained flight on harvested energy alone.
That distinction is the entire company. The next milestone Sanghvi named is energy-neutral dynamic soaring, meaning the aircraft holds altitude with its propulsion switched off, living on what it pulls out of the wind. What Alteon has shown so far is a very tight autonomous maneuver near a moving surface, which is hard, and which is not the same thing as staying up.
The company has a team of 20 in Bengaluru, a 10,000-square-foot facility, and a build rate of four to five aircraft a week. Sanghvi says it has flown more than 200 test flights in the past 30 days.
Researchers Call The First Result Promising And The Next Step Much Harder
Gabriel Bousquet, who studied dynamic soaring for his MIT doctorate, called the low-altitude flight over water a “promising first result”. Bharath Swaminathan, whose IIT Madras PhD covered the stability of dynamic soaring, said the underlying physics is well established. Both located the difficulty in real winds rather than in theory.
Bousquet told TechCrunch that flying low enough to harvest the energy safely is the hard part, because the aircraft has to handle turbulence, waves, spray, rain, and shifting light while sensing and reacting to a surface that will not hold still. Swaminathan added that large-scale wind patterns may be predictable while local shear and turbulence are not, and that some of those problems only surface in flight test.
He was generous about the attempt anyway. Keeping an aircraft up for several days on dynamic soaring alone would be “a very big step, and a big achievement”, he said.
American Money Is Funding A Capability The US Navy Has Chased Since 2020
Groom led the round, and Alteon’s earlier backers were Emergent Ventures, run from the Mercatus Center at George Mason University, and 1517 Fund, started by the team behind the Thiel Fellowship. American capital is paying for a capability the US Navy has been working on since 2020.
That work has been expensive. DroneXL reported in August 2025 on the Navy flying Skydweller, a solar aircraft with a 236-foot wingspan, for 73 hours nonstop out of Stennis, Mississippi, as part of the Autonomous Maritime Patrol Aircraft effort. That same aircraft departed Stennis on April 26, 2026, logged 8 days and 14 minutes flying the Navy’s FLEX 26 exercise and waiting out weather afterward, then ditched in the Gulf on May 4 after meeting conditions worse than forecast on the transit home. Skydweller’s own account says the airframe and autonomy were nominal and the batteries were the constraint.
Groom did not pretend the Alteon bet is safe. “Ambitious problems are always going to come with risks,” he told TechCrunch, adding that he backed the team rather than the odds.
The round lands in a market that has started attracting real money. Indian defense drone maker Raphe mPhibr raised $100 million in June 2025, and Bengaluru has been building the sensor side of this for years, including ideaForge’s stake in GalaxEye in 2024. Sanghvi is also not the first twenty-something to raise serious capital against a hard aerospace problem, as DroneXL reported in November 2025. Alteon’s $2.5 million is small next to those numbers, which is part of the point.
DroneXL’s Take
I have watched this category lose airframes for years, so my reflex on a year-aloft claim is to discount it hard. What stops me discounting Alteon is the size of the thing. The programs chasing persistence have been built around enormous aircraft. Alteon’s is not.
The aircraft that went into the Gulf in May was the converted Solar Impulse 2, a 236-foot solar plane that once carried a human around the planet, and it sank because the batteries ran flat on the way home. Alteon wants the same job done by something closer in size to a hobby glider, and it is building four or five of them a week. Cheap airframes fail cheaply, and you learn faster when a crash costs a weekend instead of a program.
The strongest case against my interest here is Bousquet’s, and it is a good one. The distance between one clean demonstration over the Bay of Bengal and reliable energy extraction in weather nobody chose is exactly where this category keeps dying. Swaminathan can be right that the physics is settled and Alteon can still spend three years failing to build a machine that survives a monsoon at three feet off the water. Correct physics did not keep Skydweller out of the Gulf.
One number Alteon has not given: its longest single flight. The funding announcement offers 200 test flights in 30 days and a seven-cycle demonstration, and the company’s website leads with aircraft that fly “months, not hours” rather than with a figure. Endurance is the whole product. Until there is a duration attached to it, this is a maneuver with a funding round stapled to it.
Watch the milestone Alteon set for itself, because it is falsifiable in a way a press release is not: energy-neutral dynamic soaring, with the propulsion switched off and the aircraft holding station on wind alone. That flight either happens or it does not. Watch the Navy and Skydweller investigation into the May ditching too, which has issued no findings yet. If it lands on energy margin rather than structure, the argument for small wind-harvesting aircraft over enormous solar ones gets much easier to make, and $2.5 million starts to look less like a moonshot and more like a cheap option on a problem the incumbents have not solved.
Source: TechCrunch, Alteon, Skydweller Aero
DroneXL uses automated tools to support research and source retrieval. All reporting and editorial perspectives are by Haye Kesteloo.
