Sonex Aircraft

Sonex Aircraft designs and sells kit aircraft, plans, engines and accessories for people who build their own aeroplanes. The company is in Oshkosh, Wisconsin, and was founded in 1998 by John Monnett. In May 2026 ON Capital bought the assets of Sonex Aircraft, AeroConversions and Sonex Aerospace, and the business now trades as Sonex Aviation LLC.

Aircraft

• Sonex-B and Waiex-B: two-seat sport aircraft, the Waiex with a Y-tail
• Xenos-B motorglider
• Onex: a single-seat aircraft, popular with EAA chapter and school build projects
• SubSonex personal jet
• Sonerai sport aircraft
• Sonex Highwing: tail kits began shipping in January 2026, with fuselage kits and quick build production to follow
• Sonex Phoenix: in development, with final design refinements under way in 2026

Kits and options

• Complete airframe kits, quick build kits, sub-kits and plans for scratch building
• Engine options including AeroConversions AeroVee engines, UL Power engines and ring and bed mounts for Rotax 912 installations
• Sensenich propellers, instruments, upholstery, EarthX lithium batteries and hardware kits
• Sonex Education Initiative starter packs for schools and youth programmes

Support

• Manuals, drawing revisions, service bulletins, video tips and webinars
• A searchable builder database of flying aircraft and projects under construction
• Transition training and ownership transfer for used kits and aircraft
• Factory tours by appointment, Monday to Friday; demo rides are not offered

People

• Stephen Osborne, managing member of Sonex Aviation LLC and founder of ON Capital, a lifetime EAA member and warbird pilot
• Mark Schaible, aircraft designer, with Sonex since 2003
• John Monnett, founder and advisor emeritus

Contact

Email: sales@sonexaircraft.com

FAQ

Is Sonex still in business?

Yes. In May 2026 ON Capital acquired the assets and the company is open and in production as Sonex Aviation LLC.

Can I get a demo flight?

No. The company suggests using its builder database to find a Sonex owner near you.

Details from the company's website, sonexaircraft.com, October 2026.