US Navy prepares to test Poseidon Seagull cargo drone for stealth logistics in contested waters
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As reported by CUAS News on June 19, 2025, Poseidon Aerospace, a startup headquartered in San Francisco and founded in January 2023 by David Zagaynov, Parker Tenney, and Isaac Baumstark, is developing unmanned cargo aerial vehicles (UCAVs) designed to operate in ground effect above water surfaces. The company publicly introduced its first operational vehicle, the Seagull, in March 2025 and is currently developing a second, larger vehicle called the Heron. Both platforms are based on the aerodynamic principles of ground-effect flight and are intended for use in logistics and potentially in defense operations, including upcoming testing with the U.S. Navy.Follow Army Recognition on Google News at this link
The Poseidon Seagull has a range of 120 miles and can carry up to 45 pounds of cargo, although in some cases, payload capacity has been cited as reaching up to 100 pounds. (Picture source: Poseidon Aerospace)
The Seagull is an unmanned sea glider with a wingspan of 13 feet, designed to fly a few meters above water to exploit ground effect. It is constructed from carbon fiber and aerospace-grade composites and is equipped with an autonomous control system based on two modified open-source autopilot frameworks. It has a range of 120 miles and can carry up to 45 pounds of cargo, although in some cases, payload capacity has been cited as reaching up to 100 pounds. Poseidon has confirmed that the Seagull will begin commercial logistics operations in August 2025 and undergo testing with the U.S. Navy and U.S. Coast Guard starting in July. The vehicle has no cockpit or life-support systems due to its uncrewed design, which reduces manufacturing complexity and operational overhead. It uses Starlink connectivity for remote control and telemetry, and its flight path within the ground-effect regime allows it to achieve increased lift and reduced drag. According to company sources, this mode of operation enables the Seagull to transport high-priority goods, such as medical supplies, more efficiently than conventional air cargo or maritime shipping.
Poseidon’s second vehicle, the Heron, is a larger ground-effect cargo platform currently under development. According to official data, it is designed with a 50-foot wingspan and a 1,500-mile operational range, and it will be capable of carrying a payload of up to two tons. The Heron is intended for regional and inter-island logistics missions, including routes to areas with minimal or no existing infrastructure. The aircraft will also rely on ground-effect flight, allowing it to fly low over water with increased lift and fuel efficiency. Like the Seagull, the Heron is being designed for autonomous operations and will not require ports, runways, or other conventional infrastructure. The company presents the Heron as suitable for both commercial and defense-related logistics missions, including contested or remote zones. Poseidon describes this platform as capable of addressing a logistics gap between slow ocean freight and high-cost air cargo. Cost comparisons provided by the company claim Poseidon’s operational cost in Hawaii is $2 per kilogram versus $8 for regional air freight, $3 per kilogram in Greece compared to $7, and $2 per kilogram in the Caribbean compared to $5.
Poseidon Aerospace emphasizes that its vehicles do not rely on traditional aviation infrastructure. Both the Seagull and Heron take off and land on water, eliminating the need for runways and reducing operational constraints linked to airport fees, airspace management, and terminal congestion. Additionally, their classification as Coast Guard–regulated platforms rather than Federal Aviation Administration–regulated aircraft reduces some of the regulatory hurdles for early-stage operations. Their autonomous operation further simplifies logistics by eliminating the need for onboard crew and related systems. Ground-effect flight allows the vehicles to remain below radar detection while flying high enough to avoid sonar, a flight profile that the company claims provides stealth advantages in certain scenarios. The company has announced that it will begin larger-scale production within the year and is currently finalizing vehicle configurations for manufacturing scale-up. Poseidon Aerospace also received a $1.4 million pre-seed investment round led by Starship Ventures and Draper Startup House and is currently hiring aerospace, mechanical, and composite engineers to expand its development and production capacity.
Poseidon conducts all engineering and production work at its 15,000-square-foot facility located in the Dogpatch area of San Francisco, which historically served as a shipbuilding district. The startup’s origins include early development based on self-funding and repurposed equipment. The team began with limited resources, using second-hand tools and recycled office equipment. One test was conducted in a duck pond in the middle of the night, during which one of the co-founders entered the water to retrieve the vehicle manually. Another field test nearly ended with the loss of a six-foot prototype, which was recovered with the help of local residents. These events occurred prior to Poseidon acquiring a dedicated safety boat for future demonstrations. The company refers to this phase as its early prototyping stage, which led to its first successful vehicle and initial investor interest. Zagaynov has stated publicly that the Seagull is the result of six months of iterative development and that the current version incorporates lessons learned from these early experiments.
Poseidon identifies its concept as part of a broader return to the ground-effect vehicle (GEV) design, originally explored during the Cold War. A ground-effect vehicle (GEV), also known as a wing-in-ground-effect craft or ekranoplan, is a low-flying vehicle that exploits the aerodynamic ground effect, which is the increased pressure beneath the wing and reduced drag experienced when flying close to the surface of water, ice, or flat land. These aircraft rely on forward motion to generate dynamic lift and typically fly a few meters above the surface. The design allows for significantly reduced lift-induced drag compared to conventional aircraft, enabling increased fuel efficiency and payload capacity at low altitude. Unlike hovercraft, which rely on a cushion of pressurized air from fans, GEVs require forward motion to generate lift, using short wings that perform efficiently near the surface by suppressing wingtip vortices. GEVs do not typically fly out of ground effect, though some types can temporarily reach altitudes up to 150 meters or more, depending on their classification. However, most GEVs remain close to the surface due to operational constraints and design limitations. Their operation enables higher speeds than marine vessels and better fuel efficiency than equivalent aircraft, but also comes with constraints such as vulnerability to collisions, sensitivity to sea states, and limited maneuverability. Regulatory classification has long been a challenge, with some GEVs treated as ships and others as aircraft, especially since low production volumes have hindered the establishment of a uniform standard.
The Seagull and Heron are inspired by the Soviet KM, widely known as the Caspian Sea Monster, which was a Soviet experimental ekranoplan developed between 1964 and 1966 by the Central Hydrofoil Design Bureau under chief designer Rostislav Alexeyev. Built at the Red Sormovo plant in Gorky, it was the largest and heaviest aircraft in the world from its completion in 1966 until the Antonov An-225’s first flight in 1988. With a length of 92 meters, wingspan of 37.6 meters, and a maximum takeoff weight of 544,000 kg, the KM was powered by ten Dobrynin RD-7 turbojets, eight mounted on canards for takeoff and two on the tail for cruising, and was designed to fly at altitudes of 4 to 14 meters using ground effect, making it undetectable by many radar systems. Though officially classified as a marine vessel and operated by Soviet Navy test pilots, its structure and performance were closer to those of an aircraft. The KM’s first flight occurred on October 16, 1966, with Alexeyev himself as co-pilot, and it was tested on the Caspian Sea until 1980, when a crash caused by pilot error led to its sinking without casualties. Testing demonstrated a cruising speed of 430 km/h, a top operational speed of 500 km/h, and maximum speeds reportedly reaching 650 to 740 km/h. Despite its promise for military and rescue missions, the KM encountered engineering challenges and was never recovered or replicated after its crash. However, its design informed the later Lun-class ekranoplan, which entered limited service.
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As reported by CUAS News on June 19, 2025, Poseidon Aerospace, a startup headquartered in San Francisco and founded in January 2023 by David Zagaynov, Parker Tenney, and Isaac Baumstark, is developing unmanned cargo aerial vehicles (UCAVs) designed to operate in ground effect above water surfaces. The company publicly introduced its first operational vehicle, the Seagull, in March 2025 and is currently developing a second, larger vehicle called the Heron. Both platforms are based on the aerodynamic principles of ground-effect flight and are intended for use in logistics and potentially in defense operations, including upcoming testing with the U.S. Navy.
Follow Army Recognition on Google News at this link
The Poseidon Seagull has a range of 120 miles and can carry up to 45 pounds of cargo, although in some cases, payload capacity has been cited as reaching up to 100 pounds. (Picture source: Poseidon Aerospace)
The Seagull is an unmanned sea glider with a wingspan of 13 feet, designed to fly a few meters above water to exploit ground effect. It is constructed from carbon fiber and aerospace-grade composites and is equipped with an autonomous control system based on two modified open-source autopilot frameworks. It has a range of 120 miles and can carry up to 45 pounds of cargo, although in some cases, payload capacity has been cited as reaching up to 100 pounds. Poseidon has confirmed that the Seagull will begin commercial logistics operations in August 2025 and undergo testing with the U.S. Navy and U.S. Coast Guard starting in July. The vehicle has no cockpit or life-support systems due to its uncrewed design, which reduces manufacturing complexity and operational overhead. It uses Starlink connectivity for remote control and telemetry, and its flight path within the ground-effect regime allows it to achieve increased lift and reduced drag. According to company sources, this mode of operation enables the Seagull to transport high-priority goods, such as medical supplies, more efficiently than conventional air cargo or maritime shipping.
Poseidon’s second vehicle, the Heron, is a larger ground-effect cargo platform currently under development. According to official data, it is designed with a 50-foot wingspan and a 1,500-mile operational range, and it will be capable of carrying a payload of up to two tons. The Heron is intended for regional and inter-island logistics missions, including routes to areas with minimal or no existing infrastructure. The aircraft will also rely on ground-effect flight, allowing it to fly low over water with increased lift and fuel efficiency. Like the Seagull, the Heron is being designed for autonomous operations and will not require ports, runways, or other conventional infrastructure. The company presents the Heron as suitable for both commercial and defense-related logistics missions, including contested or remote zones. Poseidon describes this platform as capable of addressing a logistics gap between slow ocean freight and high-cost air cargo. Cost comparisons provided by the company claim Poseidon’s operational cost in Hawaii is $2 per kilogram versus $8 for regional air freight, $3 per kilogram in Greece compared to $7, and $2 per kilogram in the Caribbean compared to $5.
Poseidon Aerospace emphasizes that its vehicles do not rely on traditional aviation infrastructure. Both the Seagull and Heron take off and land on water, eliminating the need for runways and reducing operational constraints linked to airport fees, airspace management, and terminal congestion. Additionally, their classification as Coast Guard–regulated platforms rather than Federal Aviation Administration–regulated aircraft reduces some of the regulatory hurdles for early-stage operations. Their autonomous operation further simplifies logistics by eliminating the need for onboard crew and related systems. Ground-effect flight allows the vehicles to remain below radar detection while flying high enough to avoid sonar, a flight profile that the company claims provides stealth advantages in certain scenarios. The company has announced that it will begin larger-scale production within the year and is currently finalizing vehicle configurations for manufacturing scale-up. Poseidon Aerospace also received a $1.4 million pre-seed investment round led by Starship Ventures and Draper Startup House and is currently hiring aerospace, mechanical, and composite engineers to expand its development and production capacity.
Poseidon conducts all engineering and production work at its 15,000-square-foot facility located in the Dogpatch area of San Francisco, which historically served as a shipbuilding district. The startup’s origins include early development based on self-funding and repurposed equipment. The team began with limited resources, using second-hand tools and recycled office equipment. One test was conducted in a duck pond in the middle of the night, during which one of the co-founders entered the water to retrieve the vehicle manually. Another field test nearly ended with the loss of a six-foot prototype, which was recovered with the help of local residents. These events occurred prior to Poseidon acquiring a dedicated safety boat for future demonstrations. The company refers to this phase as its early prototyping stage, which led to its first successful vehicle and initial investor interest. Zagaynov has stated publicly that the Seagull is the result of six months of iterative development and that the current version incorporates lessons learned from these early experiments.
Poseidon identifies its concept as part of a broader return to the ground-effect vehicle (GEV) design, originally explored during the Cold War. A ground-effect vehicle (GEV), also known as a wing-in-ground-effect craft or ekranoplan, is a low-flying vehicle that exploits the aerodynamic ground effect, which is the increased pressure beneath the wing and reduced drag experienced when flying close to the surface of water, ice, or flat land. These aircraft rely on forward motion to generate dynamic lift and typically fly a few meters above the surface. The design allows for significantly reduced lift-induced drag compared to conventional aircraft, enabling increased fuel efficiency and payload capacity at low altitude. Unlike hovercraft, which rely on a cushion of pressurized air from fans, GEVs require forward motion to generate lift, using short wings that perform efficiently near the surface by suppressing wingtip vortices. GEVs do not typically fly out of ground effect, though some types can temporarily reach altitudes up to 150 meters or more, depending on their classification. However, most GEVs remain close to the surface due to operational constraints and design limitations. Their operation enables higher speeds than marine vessels and better fuel efficiency than equivalent aircraft, but also comes with constraints such as vulnerability to collisions, sensitivity to sea states, and limited maneuverability. Regulatory classification has long been a challenge, with some GEVs treated as ships and others as aircraft, especially since low production volumes have hindered the establishment of a uniform standard.
The Seagull and Heron are inspired by the Soviet KM, widely known as the Caspian Sea Monster, which was a Soviet experimental ekranoplan developed between 1964 and 1966 by the Central Hydrofoil Design Bureau under chief designer Rostislav Alexeyev. Built at the Red Sormovo plant in Gorky, it was the largest and heaviest aircraft in the world from its completion in 1966 until the Antonov An-225’s first flight in 1988. With a length of 92 meters, wingspan of 37.6 meters, and a maximum takeoff weight of 544,000 kg, the KM was powered by ten Dobrynin RD-7 turbojets, eight mounted on canards for takeoff and two on the tail for cruising, and was designed to fly at altitudes of 4 to 14 meters using ground effect, making it undetectable by many radar systems. Though officially classified as a marine vessel and operated by Soviet Navy test pilots, its structure and performance were closer to those of an aircraft. The KM’s first flight occurred on October 16, 1966, with Alexeyev himself as co-pilot, and it was tested on the Caspian Sea until 1980, when a crash caused by pilot error led to its sinking without casualties. Testing demonstrated a cruising speed of 430 km/h, a top operational speed of 500 km/h, and maximum speeds reportedly reaching 650 to 740 km/h. Despite its promise for military and rescue missions, the KM encountered engineering challenges and was never recovered or replicated after its crash. However, its design informed the later Lun-class ekranoplan, which entered limited service.
