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: Aircraft Valuation Methodology · Avionics Pricing Reference · GA Insurance Underwriting · Maintenance Ecosystem Related missions: Cross-Country Flying · 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 Flying 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 Reference.

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 $42,000+ 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 Aircraft 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 GA Insurance Underwriting.