Stavatti Proposes SM-940K Tanker for U.S. Air Force’s NGAS Program

Stavatti Aerospace has unveiled its SM-940K stealth tanker concept as a candidate for the U.S. Air Force’s Next Generation Aerial Refueling System (NGAS), also known as KC-Z. The proposal introduces a radical flying wing design intended to meet future survivability and interoperability demands in contested airspace. While ambitious in scope and unconventional in form, the SM-940K faces stiff competition and credibility challenges in a domain dominated by established aerospace giants.

NGAS Program Overview and Strategic Context

The U.S. Air Force’s NGAS initiative aims to develop a next-generation aerial refueling platform to replace or supplement the aging Boeing KC-135 and eventually the KC-46A Pegasus fleet by the 2040s. Unlike previous tanker programs focused on legacy airliner derivatives (e.g., KC-135 from Boeing 707; KC-46A from 767), NGAS envisions a survivable platform capable of operating within anti-access/area-denial (A2/AD) environments alongside fifth and sixth-generation fighters such as F-35s and future NGAD aircraft.

Critical attributes sought include:

• Low observability (LO) / stealth features
• Advanced defensive systems and situational awareness
• Long-range refueling capability with high fuel offload capacity
• Interoperability with manned-unmanned teaming concepts

The program is currently in early conceptual stages with an anticipated fielding timeline post-2040. Major primes such as Lockheed Martin (LMXT) and Boeing are expected to compete aggressively.

The Stavatti SM-940K Concept: Design Features and Specifications

The Stavatti SM-940K is proposed as a low-observable flying wing aerial refueler—a configuration reminiscent of Northrop Grumman’s B-2 Spirit bomber or RQ-180 ISR aircraft. According to Stavatti’s initial renderings and statements:

• Configuration: Flying wing with blended body-fuselage design
• Dimensions: Wingspan approximately 80 meters; length around 35 meters (estimated based on visuals)
• Propulsion: Four turbofan engines embedded within upper fuselage nacelles for reduced radar cross-section
• Crew: Two-person cockpit with optional autonomous/unmanned modes envisioned long-term
• Tanker Systems: Boom refueling system compatible with USAF receivers; potential hose-and-drogue adaptability not confirmed

The aircraft would be constructed using radar absorbent materials (RAM), edge-aligned surfaces, internal fuel storage exceeding current tankers (~200,000+ lbs offload capacity projected), and advanced mission systems for threat detection and evasion.

A Radical Proposal from an Unproven Contender

While Stavatti has previously announced multiple advanced aerospace concepts—including fighter jets like the F/A-37 Talon or Machete series—none have reached prototype or production stages. The company lacks a track record of delivering certified military aircraft or securing major defense contracts.

This raises questions about whether Stavatti can realistically compete against established OEMs like Lockheed Martin or Boeing that possess mature engineering teams, production infrastructure, supply chains, flight test experience, and strong relationships with DoD acquisition offices.

The SM-940K appears more aspirational than operational at this stage. No wind tunnel testing data, propulsion partner details, or full-scale mockups have been disclosed publicly as of October 2025.

Boeing vs Lockheed vs Others: Competitive Landscape for NGAS/KC-Z

Boeing is expected to offer an evolved version of its KC-X/KC-Y lineage—likely a stealthier variant of the KC-46A Pegasus or potentially a clean-sheet design leveraging lessons from BWB demonstrators like X-48B/C.

Lockheed Martin had previously proposed the LMXT—a modified Airbus A330 MRTT—for the interim KC-Y competition but may pivot toward a stealthier solution for NGAS/KC-Z aligned with its work on NGAD platforms.

Northrup Grumman remains a dark horse contender given its expertise in flying wings (B-2/B-21) but has not officially declared intent to enter NGAS yet. General Atomics could also propose an unmanned tanker concept building on MQ-25 Stingray technologies if Navy-Air Force convergence occurs in future doctrine.

Main Competitor Concepts Likely Include:

• Boeing “Stealth Pegasus” Variant: Possibly based on blended-wing demonstrators or new airframe optimized for LO operations.
• Northrup Grumman BWB Tanker: Leveraging B21/BWB heritage if entered into competition.
• Manned-Unmanned Teams: Future tankers may operate alongside autonomous ISR/strike drones under CCA-type control schemes.
• Morphing Modular Designs: Some proposals may explore modular payload bays or plug-and-play fuel/offload configurations tailored per mission profile.

A Long Road Ahead Before Downselect Decisions

The U.S. Air Force has not yet issued formal RFPs for NGAS/KC-Z but is funding multiple studies under AFWERX/STTR/SBIR pathways to explore disruptive aerial refueling concepts through FY2027–2030 horizon planning cycles. Any downselect process would likely occur no earlier than mid-to-late 2030s following extensive modeling & simulation phases plus technology maturation efforts under DARPA/AFRL guidance.

If Stavatti seeks serious consideration for the program, it must demonstrate substantial progress including prototype development milestones, flight testing plans, validated LO performance data (RCS modeling), propulsion partnerships (e.g., GE/RR/PW), and secure DoD interest through funded study participation or tech demonstrations at venues like AFRL’s Skyborg Vanguard initiative or XPONENTIAL/ACES showcases.

Conclusion: Bold Vision Meets Harsh Realities

The SM-940K reflects bold thinking about what future tankers might look like—stealthy platforms capable of surviving near-peer threats while supporting distributed operations across Indo-Pacific or European theaters. However, without tangible hardware progress or institutional support from DoD stakeholders, it risks remaining another paper plane among many unbuilt visions in aerospace history.

If Stavatti can overcome credibility gaps through strategic partnerships and deliver working prototypes within this decade—it could become an unexpected disruptor in one of the most consequential military aviation competitions ahead.