Ondas to Buy Stemme and Target 10 ULTRA ISR Aircraft a Month by 2028

Ondas Inc. on Thursday, November 5, 2026, said it had signed a definitive agreement to buy 100% of Stemme GmbH for cash. Stemme, based in Strausberg and Pasewalk, Germany, builds the type-certified S12 composite airframe used on Ondas' ULTRA long-endurance intelligence, surveillance, and reconnaissance aircraft. The U.S. Air Force already flies ULTRA.

Chairman and CEO Eric Brock said the deal is meant to lock airframe capacity, cost, and schedule as Ondas adds U.S. production. Ryan Hartman, president and CEO of Ondas Sentinel, said putting the airframe, engineering, and line under one roof is how the company answers demand. Stemme co-CEOs Koenraad Geurts and Benjamin de Broqueville said they will continue inside the Ondas Sentinel group. Close is expected in the first quarter of 2027, subject to customary conditions and regulatory approvals. Ondas did not publish a price.

Key details

• ULTRA endurance and payload as stated by Ondas: more than 70 hours, over 400 pounds. Payloads include electro-optical/infrared, radio-frequency collection, and communications relay.
• Stemme German plants: about 135,571 square feet, running at about 25% of capacity. Planned U.S. airframe floor: 345,000 square feet.
• Stemme holds EASA, Luftfahrt-Bundesamt, and FAA airworthiness approvals and an FAA Part 145 repair station.

Eric Brock said acquiring Stemme would give Ondas greater control over airframe capacity, cost, and schedule as it brings production to the United States.

Why it matters

ULTRA is already a U.S. Air Force uncrewed ISR aircraft on a certified motor-glider airframe. Ondas is buying that German OEM so it can raise output instead of remaining a customer of an external S12 shop, matching the Department of War's published push for lower-cost, attritable aircraft alongside crewed collectors.