Glasair III

Stoddard-Hamilton Aircraft, the original Glasair company, started in 1980 in Arlington, Washington. The first Glasair was a low-wing two-seat composite kit that offered better performance than the dominant aluminum kits of the era. The Glasair II followed in the mid-1980s with refined construction and a wider engine range. The Glasair III arrived in 1988 as the high-performance flagship, designed around the Lycoming IO-540 angle-valve and intended to compete with the fastest piston singles in general aviation.

Stoddard-Hamilton sold complete kits through the 1990s. The company changed hands several times and the kit business eventually moved to Glasair Aviation in Arlington, which continues to support the legacy fleet as of 2026 but doesn't actively sell new Glasair III kits. The fleet is therefore finite. Most flying Glasair IIIs were completed between 1990 and 2010, with a small number of more recent builds finished from old kits.

As of mid-2026, fewer than 300 Glasair III airplanes are estimated to be flying in the United States. The community is smaller and more specialized than the Van's community. Pre-buy expertise is concentrated in a handful of inspectors and shops, mostly in the Pacific Northwest where the type originated. Glasair Owners Association is the primary type club.

The Glasair III is built for cruise speed. At 8,000 feet with the 300 hp IO-540 angle-valve, the airplane turns 180 to 195 KTAS at 75% power, burning 13 to 15 gph. Lean-of-peak operation pulls cruise burn down to 12 to 13 gph at long-range power settings. That's directly competitive with a Cirrus SR22 normally aspirated and faster than a Bonanza A36 by 15 to 20 knots.

Useful load is the trade. A typical Glasair III with full fuel (90 gallons) has 520 to 580 pounds left for two adults and bags. That's the load you'd find in a slow two-seater, not a serious cross-country airplane. Most Glasair III pilots fly with partial fuel and longer legs are limited by passenger and bag weight rather than tank capacity. Range at full fuel works out to 1,100 to 1,300 nm with reserves.

Handling is everything you'd expect from a small composite retractable. Light controls, fast roll rate, and quick energy management. The airplane is not a forgiving short-field airplane. Stall speed is high (about 65 knots), pattern speeds run 110 to 120 knots, and landing distance reflects the high wing loading. Most Glasair III pilots operate from runways of 3,000 feet or longer.

The Lycoming IO-540-K1G5 (300 hp angle valve, fuel injected) is the canonical engine. Some Glasair IIIs run the IO-540-K1H5 or other angle-valve variants. All produce 300 hp at takeoff and share the same maintenance profile. Lycoming's published TBO for the angle-valve IO-540 K series is 2,000 hours per Lycoming Service Instruction 1009 BE, advisory in experimental service.

Field overhaul of an IO-540 angle-valve runs $50,000 to $75,000 in 2026 at a name-brand shop. The angle-valve adds $5,000 to $10,000 to overhaul cost versus a parallel-valve IO-540 because of more complex valve train work. Factory rebuild is closer to $95,000 to $110,000 at current Lycoming pricing. Owner-assisted overhauls are legal in experimental service and the Glasair community has shop recommendations for shops that handle angle-valve work well.

The Hartzell HC-I3YR three-blade constant-speed prop is the most common. Composite three-blade props from MT are popular alternatives on later builds. Both run on a 2,400-hour or six-year overhaul cycle per Hartzell Service Letter HC-SL-61-61Y Rev 12. Hartzell overhaul runs $4,500 to $7,500 in 2026. The MT composite is in a similar range.

The Glasair III is one of the more expensive experimentals to operate per hour. The IO-540 angle-valve burns more fuel than most piston singles, the retractable gear adds maintenance complexity, and the composite airframe demands specialized inspection knowledge.

If you built it: fuel runs $80 to $110 per hour at $5.50 to $7 per gallon and 13 to 15 gph. Engine reserve is $25 to $38 per hour ($50,000 to $75,000 overhaul amortized across 2,000 hours, with experimental TBO advisory). Prop reserve is $2 to $3 per hour. Airframe maintenance reserve is $15 to $25 per hour, the high end of the experimental range because of retractable gear and composite-specific work. All-in at 100 hours a year runs $140 to $195 per hour, plus $5,000 to $9,000 in annual fixed costs.

If you bought it used: realistic all-in at 100 hours a year is $170 to $230 per hour. Insurance is meaningful. Composite retractable airplanes with 300 hp engines carry premiums in the $4,000 to $7,000 range for experienced pilots. New buyers with limited Glasair time face $6,000 to $10,000 in first-year premiums.

Acquisition cost in mid-2026 runs $130,000 to $195,000 for a clean Glasair III with a working glass panel and recent paint, $195,000 to $275,000 for a low-time example with current avionics. The Glasair III market is thin and prices vary widely based on build quality, engine time, and avionics.