Wing Derringer D-1

The Wing Derringer D-1 is a rare two-seat light twin designed by John Thorp in the late 1950s (originally as the Thorp T-17, a twin-engine derivative of his T-11 Sky Scooter) and developed into production form by George Wing of the Hi-Shear Corporation. George Wing — inventor of the Hi-Shear rivet and Hi-Lok fastener and a successful aerospace-fastener industrialist — wanted a "sports car" of the sky: a tiny, fast, retractable-gear twin with the footprint of a trainer and the speed of a Bonanza.

The prototype (N3621G) first flew on May 1, 1962, at Torrance, California. A second prototype flew in November 1964 but was lost weeks later to an in-flight airframe failure. The type certificate (A21WE) was issued December 20, 1966, but Hi-Shear never put the aircraft into serial production. In 1978, George Wing left Hi-Shear to form the Wing Aircraft Company specifically to build the Derringer. Wing Aircraft completed one pre-production aircraft and six production machines before entering bankruptcy in July 1982. One additional aircraft was later assembled from parts, and seven unfinished airframes were sold off. Total production: approximately 12 airframes, of which roughly 7 remain on the FAA register.

The Derringer is an enthusiast's airplane — owned by collectors, engineers, and pilots who value its unique blend of twin-engine safety and tiny footprint. It is not a practical family airplane and never will be. It is a footnote in GA history but a memorable one: arguably the prettiest two-seat twin ever certificated in the United States.

Only the D-1 production variant is commonly encountered. All flying Derringers today are D-1s.

The Derringer is extraordinarily fast for its power class. With 320 hp total, it cruises at 184 KTAS at 13,000 ft on 15.8 gph — speeds competitive with a Bonanza A36 that has nearly twice the horsepower and burns twice the fuel. This is a consequence of an exceptionally clean airframe, small wing (shorter span than a C150, less wing area than a Tomahawk), and tight cowlings around the small-displacement IO-320s.

Real-world cruise is reported at 180-190 KTAS depending on altitude and power setting. Single-engine performance is modest: with only 160 hp per side and a clean high-Vmc airframe, Vmc handling demands currency and attention. Single-engine service ceiling is approximately 7,000 ft, which is acceptable for a light twin but not generous.

The small wing makes the Derringer stiff in turbulence and sensitive to crosswinds on landing; approach speeds are higher than owners expect for a two-seater (over-the-fence around 80 KIAS). Density altitude performance is respectable thanks to the high rate of climb (1,700 fpm sea level, both engines).

With a useful load of 950 lb and 87 usable gallons (522 lb of fuel at full tanks), the payload-range trade is:

• Full fuel + 2 pax + bags: 950 - 522 = 428 lb for two people and baggage. Two 175-lb pilots leaves 78 lb for bags — tight but workable for a weekend trip. Range at this loading: ~1,000 nm economy, ~850 nm at 184 KTAS cruise.
• Two pax at 180 lb + 50 lb bags (410 lb): 540 lb fuel capacity = 90 gallons, but tanks hold only 87 usable, so fuel is the limit, not weight. Full tanks are possible with two average adults.
• Practical reality: The Derringer is almost always weight-limited before it is fuel-limited when carrying two people. It is a genuine 2-person, full-fuel, 900+ nm airplane — which is remarkable for a 320-hp twin but is its only useful mission profile. There is no "four people and bags" fallback.

Related references: valuation-methodology · avionics-pricing · insurance-underwriting · maintenance-ecosystem Related missions: cross-country · local-fun-flying

• Cross-country (7): Genuinely fast, long-legged (1,000+ nm range), twin redundancy over water or mountains. Held back only by 2-seat limit and minimal baggage.
• Local fun flying (6): Unique, eye-catching, and a genuine pilot's airplane — but expense and orphan-parts risk limit casual use.
• Business travel (5): Fast and IFR-capable, but two seats only and no meaningful baggage provision disqualify it for most business missions.
• Surveying (2): Low wing and tight cabin hurt visibility; single-engine-out considerations exist but fuel burn is reasonable.
• Flight training (1): Complex, twin, high insurance, high Vmc — completely unsuited.
• Backcountry (1): Retractable low-wing twin with small wheels; not remotely suited.
• Aerobatics (1): Not certified for aerobatics.
• Cargo hauling (1): 950 lb useful load with 522 lb of fuel leaves ~428 lb for two people and bags — tight.

See cross-country and local-fun-flying mission pages for scoring rubrics.

Surviving Derringers were delivered with typical late-1970s/early-1980s King Silver Crown panels (KX-170B/KX-175B, KI-214, KMA-24, KT-76A transponder). Because the aircraft is rare and owned by enthusiasts, most flying examples have been upgraded ad-hoc to modern IFR capability:

• Entry tier (~$120k airframes): Original King panel, perhaps a GNC-255 nav/comm and a used GTX-327 transponder to meet ADS-B. Not practical IFR in 2026.
• Mid tier (~$175k): GNS-430W or GTN-650, GTX-345 ADS-B out/in, digital engine monitors (EDM-760 twin).
• Premium tier (~$250k): Dual GTN navigators, G5 or GI-275 HSI/ADI, STEC-30 or similar autopilot, full engine monitor, ADS-B in/out.

Panel upgrades are limited only by the owner's willingness to spend — there are no type-specific avionics STC hurdles because the aircraft's certification basis is simple and it has no factory supplemental STC library to honor. See avionics-pricing.

The Derringer has essentially no aftermarket STC ecosystem — the production run was too small to attract STC developers. A handful of owner-specific field approvals exist (vortex generators, engine monitor installs, modern radios). No gross-weight, horsepower, or speed-mod STCs are available. Any major modification requires one-off engineering approval via DER and FAA ACO, which is expensive and time-consuming.

This is the Derringer's Achilles heel. There is no factory, no type club of meaningful size, no PMA parts supplier, and no A&P community that sees these aircraft regularly.

• Parts availability: poor. Engine, prop, wheels, brakes, tires, magnetos, and standard AN hardware are off-the-shelf. Everything specific to the airframe — gear components, cowlings, fairings, flap tracks, windshield, interior plastics — is unobtainium and must be fabricated.
• Mechanic familiarity: rare. Virtually no working A&P has seen more than one Derringer. Owners typically form a direct relationship with a trusted IA willing to research and fabricate as needed.
• Annual cost: $8,000-$15,000 in a normal year (dual engines, retractable gear), with the real risk being a $30,000+ year if a bespoke part fails.
• Expensive items: Dual engine overhauls ($55-70k total), prop ODs ($6-8k each), gear rigging/overhaul, any airframe-specific structural repair.

Cleveland still supports the wheel and brake parts. Lycoming fully supports the IO-320-B1C. Everything else is on the owner. See maintenance-ecosystem.

Because only ~7 airworthy examples exist, there is no meaningful market comparable. Asking prices over the last decade have ranged from roughly $100,000 for project/run-out airframes to $250,000 for well-kept, upgraded examples. A typical flying, IFR-equipped Derringer trades around $150-$200k when one appears — which is rare (zero listed on Trade-A-Plane as of this writing).

Value drivers:

• Engine time. Dual overhaul is ~$60,000+ on these small Lycomings, plus removal/install. A fresh-overhaul airframe is worth $30-50k more than a mid-time example.
• Avionics. A GTN-equipped, ADS-B-compliant panel adds $30-60k.
• Logs and provenance. Because the fleet is so small, complete, traceable logs back to the Wing Aircraft factory are essential to value. Broken log chains crater the price.
• Paint and interior. Collectors pay premiums for well-preserved factory-original finishes.
• Airframe time. Total time matters less than condition and corrosion history; most examples have very low total time.

See valuation-methodology for engine and avionics valuation formulas.

There are no widely publicized recurring ADs specific to the Derringer airframe — the in-service fleet is too small to generate meaningful AD activity. However, ADs on the Lycoming IO-320-B1C engines, Hartzell constant-speed props (including the blade-fatigue inspection ADs), Bendix magnetos, and Cleveland wheels and brakes all apply normally.

Known problems and pre-buy red flags:

• Orphan parts. No type-club parts pool, no factory, and no surviving supplier network. Airframe-specific components (gear doors, flap tracks, fairings, cowlings, windshield) must be fabricated from drawings or salvaged.
• Structural history. The second prototype was lost to in-flight structural failure. Surviving aircraft should have detailed wing-spar and empennage inspections documented.
• Landing gear. Retraction system is bespoke and rigging is a specialist task; gear problems are the most commonly reported operational issue.
• Fuel system. 87 usable gallons spread across wing tanks with cross-feed; fuel selectors and plumbing are unique to type and hard to service.
• Documentation. Pilot operating handbooks are available as reproductions (Essco, Pilot Mall, Flight Manuals Online), but maintenance manuals and IPCs are scarce. Pre-buy should verify complete logs back to new.

Insuring a Derringer is difficult. Underwriters treat it as a light retractable twin (multi-engine + retractable gear + high Vmc) but with an orphan-parts hull risk that makes total-loss pricing hazardous. Expect:

• Hull premium: ~3-5% of hull value annually — significantly above the ~1.5% typical for a Baron or Twinkie of comparable value — because any hull damage may be uneconomic to repair given parts scarcity.
• Liability: $1M smooth is generally available to current, multi-engine-rated owners; some underwriters will only write with named-pilot endorsements.
• Requirements: Multi-engine rating, typically 250+ hours total time, 25+ multi, and formal dual instruction in type (which is hard to find — most new owners get transition training from the seller).
• Market: Only a handful of underwriters will quote. Global Aerospace and Starr have written Derringers historically.

Typical all-in hull + liability: $5,500-$8,000/year for a $175k hull. See insurance-underwriting.