SOURCE: AFI
On May 10 and 11, 2025, India’s National Aerospace Laboratories (CSIR-NAL) marked a significant milestone in its High-Altitude Platform (HAP) program. Celebrating the anniversary of its altitude-record flight, the subscale HAP—a solar-powered unmanned aerial vehicle (UAV)—repeated its remarkable feat, climbing to 24,000 feet above mean sea level (AMSL) on both days.
The subscale HAP, a prototype of CSIR-NAL’s ambitious High-Altitude Pseudo-Satellite (HAPS) program, is designed to operate at stratospheric altitudes of 18–20 kilometers (approximately 60,000–66,000 feet). Unlike traditional satellites, HAPS offers a cost-effective alternative for applications like surveillance, telecommunications, and environmental monitoring. The vehicle’s ability to loiter for extended periods—potentially months—powered by solar energy during the day and high-density batteries at night, positions it as a game-changer in the global aerospace landscape.
The 2025 flights build on CSIR-NAL’s earlier milestones. In May 2024, the subscale HAP reached 26,000 feet during a 27-hour endurance test, carrying a synthetic aperture radar payload developed by Indian startup GalaxEye Space. That flight demonstrated the UAV’s ability to climb higher after payload delivery, showcasing its versatility. The recent tests, reaching 24,000 feet AMSL, further validate the platform’s stability, control systems, and propulsion technology, critical for scaling up to a full-size HAPS by 2027.
The subscale prototype, with a 12-meter wingspan and a weight of 23 kilograms, is a scaled-down version of the planned full-scale HAPS, which will boast a 35-meter wingspan and a 450-kilogram weight, capable of carrying a 35-kilogram payload for up to 90 days. These specifications make it a formidable competitor to Western and Chinese high-altitude platforms, aligning with India’s Make in India initiative to foster indigenous innovation.
The HAP program has garnered significant attention for its strategic applications. As noted in a 2024 Indian Express report, HAPS can enhance India’s border surveillance capabilities, particularly after incidents like the 2017 Doklam standoff. Flying at altitudes double that of commercial aircraft, the UAV can provide continuous monitoring, detect changes in terrain, and support disaster response efforts. Its potential as a “pseudo-satellite” for 5G and 6G telecommunications also promises to bridge connectivity gaps in remote areas, offering low-latency, high-bandwidth solutions at a fraction of the cost of traditional satellites.
Commercially, the HAP positions India as a contender in the global aerospace market. The success of the subscale model has drawn interest from the Indian Navy and private startups like NewSpace Research and Technologies, which are collaborating with CSIR-NAL and Hindustan Aeronautics Limited (HAL) to develop advanced HAPS. The program’s cost-effectiveness—compared to satellite launches requiring rockets—makes it an attractive option for emerging markets in Asia, Africa, and Latin America.
Developing a high-altitude platform is no small feat. CSIR-NAL has tackled significant technical challenges, including designing lightweight composite materials, embedding thin solar panels into the wings, and ensuring stability with advanced control systems. The subscale model’s ability to handle crosswinds and maintain stability at 24,000 feet is a testament to these innovations.
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