Stavatti Aerospace Submits SM-940K and SM-635 Concepts for U.S. Air Force’s Next Generation Air-Refueling System Program

Stavatti Aerospace has officially entered the U.S. Air Force’s Next Generation Air-refueling System (NGAS) program with two distinct aircraft proposals — the SM-940K transonic tanker and the SM-635 stealth blended-wing concept. Announced on October 24, 2025, the submission marks the company’s first major participation in an Air Force tanker competition, placing it among the growing list of contenders shaping the next era of aerial refueling.

The NGAS program is the U.S. Air Force’s flagship initiative to develop a next-generation tanker fleet that can operate effectively in highly contested environments. The program’s long-term objective is to replace the aging KC-135 Stratotanker and KC-10 Extender while complementing the KC-46A Pegasus, which currently serves as the mainstay of U.S. aerial refueling operations. NGAS envisions a family of systems with increased range, survivability, and adaptability—capable of supporting next-generation bombers, stealth fighters, and unmanned systems across multiple theaters with fewer sorties and greater operational flexibility.

Dual Proposal: Transonic Efficiency and Stealth Adaptability

Stavatti’s proposal offers two complementary platforms tailored for different operational needs. The SM-940K serves as a high-performance transonic conventional tanker, while the SM-635 introduces a stealth-oriented blended-wing-body design for missions where low observability is essential. This dual approach reflects the Air Force’s evolving doctrine that demands both high-capacity refueling in secure airspace and stealthy operations closer to contested zones.

The SM-940K is engineered for a maximum fuel offload of 300,000 pounds (136,000 kg), capable of refueling up to three fighter aircraft simultaneously using both flying boom and hose-and-drogue systems. It is designed to support long-endurance missions, with a ferry range exceeding 25,000 kilometers (13,500 nautical miles) and a refueling radius of 7,756 kilometers (4,189 nautical miles). This positions it well above most existing tankers in both range and payload capacity.

Engineering and Performance

Constructed with metal sandwich and composite materials, the SM-940K emphasizes strength, efficiency, and reduced weight. The aircraft features an M-wing configuration that enhances aerodynamic performance while reducing drag at transonic speeds. It measures 45.7 meters in length, with a 37.8-meter wingspan and 13.1-meter height, and has a maximum takeoff weight exceeding 226,000 kilograms (500,000 pounds).

Engine options under evaluation include the Pratt & Whitney PW1133G-JM, GE CF6-80C2B1F, and Rolls-Royce Trent 7000 series, each capable of generating 33,000 pounds of thrust, giving the aircraft a combined output near 294 kilonewtons (66,000 pounds). With a maximum cruise speed of Mach 0.97, the SM-940K ranks among the fastest heavy tankers proposed for NGAS.

In comparison with existing platforms, the SM-940K’s range and offload capacity outperform the KC-10A Extender and A330 MRTT by a significant margin. The aircraft’s short takeoff and landing performance, combined with a fuel burn rate of 1.87 kilograms per kilometer (4.125 lb per nautical mile), underlines its potential for extended-range operations with lower operating costs. The projected unit cost is around $300 million, and the estimated cost per flight hour is $18,623.

The Stealth Companion: SM-635

While the SM-940K focuses on performance and fuel capacity, the SM-635 introduces a blended-wing stealth design aimed at survivability in hostile airspace. Its low radar cross-section, internalized systems, and adaptable airframe enable operations in anti-access/area-denial (A2/AD) environments. The SM-635 could also integrate autonomous flight systems, secure data relay modules, and distributed refueling nodes, making it ideal for next-generation combat logistics.

Together, the SM-940K and SM-635 give Stavatti a flexible edge — one focusing on high-volume operations, the other on low-observable persistence. This combination offers the U.S. Air Force an opportunity to field a scalable tanker architecture, balancing fuel efficiency, speed, and survivability.

Industrial Capability and Future Vision

Founded in 1994 and restructured in 2019, Stavatti Aerospace Ltd operates from the Niagara Falls International Airport facility, spanning over 180,000 square feet. The company plans to establish a massive “2M Plant” production complex with more than 185,000 square meters of manufacturing space, intended to employ approximately 15,000 aerospace professionals.

The firm’s portfolio already includes both civil and military designs such as the SM-920 airliner, SM-920E early warning aircraft, SM-27/28 Machete close-support jets, SM-31 Stiletto, and SM-39 Razor air-superiority fighter. All share core design philosophies—modular systems, transonic aerodynamic optimization, and metal sandwich construction—which are also central to the new NGAS submissions.

Competing in a Crowded Field

The NGAS competition has drawn responses from established aerospace giants such as Lockheed Martin, Boeing, and Northrop Grumman. Boeing continues refining the KC-46A Pegasus, while Lockheed Martin promotes its LMXT (based on the Airbus A330 MRTT). In contrast, Stavatti’s clean-sheet approach brings fresh engineering solutions that prioritize performance, stealth, and mission adaptability rather than relying on derivative designs.

If the Air Force selects either of Stavatti’s proposals, it would mark a significant shift in the aerial refueling domain—introducing a new American manufacturer into a field long dominated by a few defense primes.

Toward the Future of Aerial Refueling

Stavatti’s entry into the NGAS program represents more than a single product proposal; it signifies an effort to redefine what next-generation refueling can mean. With the SM-940K’s range, speed, and payload capacity and the SM-635’s stealth and survivability, the company aims to deliver a complementary system capable of meeting the U.S. Air Force’s multi-domain operational goals for decades to come.

In a rapidly evolving strategic environment, where future conflicts may demand speed, endurance, and stealth in equal measure, Stavatti’s dual-offer strategy positions it as an unexpected yet credible contender in shaping the future of U.S. aerial refueling capability.