Sonex (Jabiru 3300)

Sonex Aircraft started in 1998 in Oshkosh, Wisconsin. John Monnett had previously built a reputation in the kit market with the Monerai sailplane and the Moni motorglider in the 1970s and 1980s. The Sonex was meant to be an aluminum kit that any motivated builder could complete in 1,000 to 1,500 hours using basic shop tools. No autoclaves, no exotic materials, no need for prior aviation experience.

The original Sonex was designed around the AeroVee, an aircraft conversion of the Volkswagen 2.0L four-cylinder air-cooled engine. Sonex Aircraft produces and supports the AeroVee directly. The Jabiru 3300 became a popular alternate engine because it offers 120 hp in a similar weight class. The 120 hp Jabiru turns the Sonex into a meaningfully faster airplane than the 80 hp AeroVee version, but it brings its own reliability questions.

Sonex has sold thousands of plans and hundreds of complete kits over the past quarter century. The fleet is large but not centralized in any one model. The basic Sonex airframe has been adapted into the Waiex (V-tail), the Onex (single-seat), and several other derivatives. As of mid-2026, Sonex Aircraft estimates several hundred Sonex airplanes flying in the United States.

Performance depends almost entirely on engine choice. An 80 hp AeroVee Sonex cruises at 105 to 115 KTAS on 3.5 to 4.5 gph of auto fuel or 100LL. A 120 hp Jabiru 3300 Sonex cruises at 125 to 135 KTAS on 5 to 6 gph. The Jabiru version climbs noticeably better at altitude and handles two adults with bags more comfortably. Most owners who buy used Sonex airplanes specify which engine they want before they start shopping because the airplanes operate at meaningfully different mission profiles.

Useful load is tight either way. A typical Jabiru 3300 Sonex has about 480 to 520 pounds of useful load. Full fuel is 16 gallons (96 pounds), leaving 380 to 420 pounds for two adults and bags. That works for two slim pilots and a flight bag. Two adults with anything resembling camping gear puts you at or near gross. The AeroVee version has slightly more useful load because the engine is lighter, but the climb performance penalty is significant.

Aerobatic limits are +6/-3 g and the Sonex is regarded as a capable sport aerobatic airplane. Most owners use the airplane for local flying, light cross-country, and the occasional aerobatic session. It's not a true cross-country traveler the way an RV-7 is.

The Jabiru 3300 is a 120 hp six-cylinder direct-drive air-cooled engine made in Australia. It's the most common upgrade engine on a Sonex and gives the airplane meaningfully better performance than the AeroVee. The Jabiru has a published top overhaul interval of 1,000 hours and a full overhaul interval of 2,000 hours per Jabiru service bulletins. Top overhaul is mandatory at 1,000 hours per Jabiru, though in experimental service that's advisory.

Top overhaul of a Jabiru 3300 runs $5,000 to $9,000 in 2026 at a name-brand shop (US Sport Planes in Shelbyville, Tennessee is the primary US Jabiru service center). Full overhaul is closer to $12,000 to $18,000. The Jabiru has had documented reliability issues with case studs, valve train, and cylinder head bolts. Pre-2015 production engines have a poor reputation. Gen 4 Jabiru engines (post-2015) addressed most of these issues but the historical reputation lingers.

The AeroVee is the budget alternative. An 80 hp AeroVee runs about $8,000 new from Sonex Aircraft and can be overhauled for $2,000 to $4,000. The performance penalty is real (you lose about 20 knots of cruise and most of the climb) but the operating economics are unbeatable in experimental aviation. AeroVee maintenance is also accessible to anyone with VW experience.

Propeller is a fixed-pitch wood Prince Aircraft or composite Sensenich GA. There's no constant-speed prop option certified for the Sonex airframe. The fixed-pitch prop is essentially zero-maintenance and overhauls on condition for $300 to $1,000.

The Sonex is the cheapest airplane to own and operate in the experimental category. The math splits based on engine choice and whether you built it.

If you built it with a Jabiru 3300: fuel runs $30 to $40 per hour at $5.50 to $7 per gallon and 5 to 6 gph. Top overhaul reserve is $5 to $9 per hour ($5,000 to $9,000 amortized across 1,000 hours). Full overhaul reserve adds $6 to $9 per hour. Airframe maintenance reserve is $5 to $10 per hour. All-in at 100 hours a year runs $55 to $85 per hour, plus $2,000 to $3,500 in annual fixed costs.

If you built it with an AeroVee: fuel runs $20 to $28 per hour at 3.5 to 4.5 gph (often on auto fuel, which is cheaper than 100LL). Engine reserve is $1 to $2 per hour because AeroVee overhauls are so cheap. All-in at 100 hours a year runs $40 to $60 per hour, plus $1,500 to $3,000 in annual fixed costs.

If you bought a used Sonex: realistic all-in is $60 to $95 per hour for a Jabiru, $50 to $75 per hour for an AeroVee. Insurance is a small line item on the Sonex because hull values are low. Most owners pay $1,000 to $2,000 a year.

Acquisition cost in mid-2026 runs $25,000 to $40,000 for an AeroVee Sonex with original avionics, $40,000 to $70,000 for a Jabiru 3300 example with a glass panel. Low-time examples with current avionics occasionally trade above $80,000. The Sonex is the cheapest way into a real two-seat experimental airplane in 2026.