Wing (Hi-Shear) D-1 Derringer

Photo by Jim Koepnick

First Impressions:  The Wing Derringer, like it’s firearm namesake, is a compact, ultra-sleek machine and is perfect for businessmen, high-rollers, or international men-of-mystery! The D-1 sports a brilliant design that gives it a “cool factor”, but the manufacturing workmanship is unequaled (bold, but true words) in the all-aluminum light twin category.  A two-seat twin is unusual, but the Derringer makes a lot of sense as a safe and compact airplane with multi-engine redundancy.

Background:  To appreciate the distinctive design and manufacturing process of the Derringer, it is important to know the man behind the plane.  The Wing Aircraft Company was not just a catchy name for an airplane company; it was named for its founder, George Wing.  His contribution to the aviation industry is immense, although largely unknown.  The Derringer is only a small part of his legacy.  Wing was a fascinating figure.  He was a self-taught engineer, a visionary and a successful businessman and entrepreneur. The concept of the Derringer began in George Wing’s young mind, while still a teenager in the 1930s.  Dropping out of high school, he began working in aviation at the age of 16; first for Martin Aircraft on the China Clipper, and then proceeding to Sikorsky, Ryan, Monocoupe, and North American. 

While at North American, Wing invented the hi-shear rivet, which reduced fastener weight by 60% and was first utilized in the P-51.  His hi-shear rivet was widely used and is considered the single most important aviation fastener from WWII to the lunar landing. Taking his patented tooling, George Wing left North American in 1943 to then found the Hi-Shear Rivet Tool Company, which became the Hi-Shear Corp in 1960.  His company has designed and manufactured components and equipment for a tremendous variety of aircraft and aerospace products for many years. 

In the late 1950s, George Wing enlisted the help of experienced aircraft designer John Thorp to build his ideal “sports car like” twin-engine, two seat airplane that he conceptualized as a teenager.  Thorp’s previous designs include the highly successful P2V Neptune, and Sky Scooter family of aircraft.  His later designs include the Thorp T-18 and Piper Cherokee.  The Derringer prototype was initially designated the T-17.  It’s interesting to take note of how similar the Derringer’s windscreen is to the Thorp T-18, which uses the same windscreen mold (but slightly truncated) as the Derringer. But why only two seats? Noting that most light twin aircraft did not make use of anything other than the front two seats 60% of time, eliminating extra seats allowed his Derringer to be shaped into a sleek and efficient “sports car of the sky”.  After the prototype and pre-production aircraft were built, he founded the Wing Aircraft Company to begin production of his Derringers.

Photo by Jim Koepnick

Design Characteristics: The Wing D-1 Derringer is an all-aluminum, two-place tricycle-gear light twin. Everything about it was extremely well conceived.  The NASA 65-2415 airfoil is the perfect compromise between needed structural strength, size, and anticipated performance. The dihedral minimizes fuselage interference drag and wet wings keep weight at a minimum.  Perhaps the most impressive part is the chemically milled, matched-hole, butt-joined skins with countersunk rivets.  Incredibly, each wing is just a single sheet of stretched aluminum.  This precision design and engineering is reminiscent of its contemporary “Century series” jets (F-100, F-104, etc.).

The D-1 has electric landing gear and flaps, and the motors are easily accessible by tilting up the pilot and copilot’s seats.  The nosewheel retracts forward, and the robust main landing gear uniquely retracts the wheels straight up with a tracked “slide” that pivots the top (not bottom) of the strut outboard into the wing, while the wheel is tucked into the engine nacelle. 

Wendell Green, proud owner of a 1967 Derringer (serial #3 – once owned by George Wing himself), rightly states that the most complicated part of the airplane is the canopy.  The entire canopy lifts up and aft, while remaining level by means of three swing arms, cables, 8 latching pins and a wooden-gripped closing handle (which has the appearance of an executioner’s switch for an electric chair).  Making it even more complex, the boarding step mechanically retracts when the canopy is closed.  The arrangement is a feat of mechanical engineering that adds a lot of “ramp appeal” to the already elegant Derringer. 

Each Derringer was hand-built and production took much longer than anticipated, and came in far over the initial listing price.  Advertised in 1969 at $40,000, the first order took five years to complete and had a final price of $100,000.  However, that first owner was so impressed with the product, he ordered another one!  Unfortunately, the supremely high quality and long production time became the aircraft’s downfall. A mere 12 D-1s were built from 1962 until 1984; the last one built from parts after production ceased in 1982.  Only 5 or 6 Derringers are still flying today.

Powerplants: Who can argue with the reliability of two 160-horsepower Lycoming IO-320s? The 66-inch Hartzell paddle propellers are short due to the relatively low-slung landing gear, but will clear the ground even with a fully compressed main landing gear strut.  87 of the 88 total gallons of fuel are usable due to the large wing dihedral and short distance to the respective engines.  To aid in single engine controllability, the right engine is canted or “toed-out” 4˚ right, and the left engine is canted out 2˚ left. 

Preflight: During the walk around, you will see many of the design advantages, which include full-span control surface piano hinges with very little clearance gaps.  The pitot tube, located on the top of the vertical stabilizer, looks like it belongs on a fighter. In fact, it is the same 13.5” Kollsman shark fin pitot tube found on a P-40! Checking the fuel level in each of the Derringer’s wing tanks is a bit of a challenge due to outboard fuel caps with a significant (6˚) wing dihedral. If the tanks are half full, you can barely see, with a flashlight, a little fuel sloshing in the wings.

Takeoff and Flight Characteristics: It would be rather difficult to forget latching the canopy before takeoff because the large closing handle is smack in front of your face, obstructing your view until it’s latched.  The canopy is sealed by activating an electric pneumatic pump, eliminating cabin noise and drafts.  During the takeoff roll, the acceleration is surprising, although it shouldn’t be when considering 320 horsepower is pulling a low-profile airplane weighing only 3,050 pounds.  Rotate at 80 mph while accelerating above Vmc (85 mph), pick the gear up while continuing above “blue line,” and finally intercept 110 mph for the remainder of the climb.  Utilize the Bendix synchroscope to match prop rpm and note the light control forces, thanks, in part, to long-arm bell cranks and pushrods.  The tall vertical stabilizer and rudder keep pedal usage to a minimum and Vmc low. The sloping nose provides fantastic visibility during all phases of flight.  The Derringer was marketed to Malaysia for use as a COIN (Counter Insurgency) attack aircraft, but ultimately was not selected.  In 1968, NASA conducted flight tests to evaluate the handling qualities on Derringer serial #2, concluding that they were “very good”, with “very low adverse yaw” and an excellent roll rate.  The six test pilots who flew the D-1 include future Apollo 13 astronaut, Fred Haise.  Serial #2 is now nearing the finish of a complete restoration by owners Doug Griffin and Shawn Mulligan.

Photo by Jim Koepnick

Landing: Flip both auxiliary fuel pumps on and slow below 170 mph before placing the gear down.  On the right side of the instrument panel is a comically small three-position flap switch, half the size of a piece of Chiclets chewing gum.  Once found, select down to extend 30 degrees of Fowler flaps.  Ninety mph on final approach and a smooth flare with a transition to idle power will provide ample time to bleed energy in ground effect before touching down around 65 mph.  Even with a perfect simultaneous touchdown on both mains, the straight oleo struts will inevitably compress one at a time and lead to a mild swerve, which is a “non-event” unless you’re trying to impress your passenger with a silky-smooth landing. 

Wrap-up: There is something about flying a Wing Derringer that just makes you want to wear a sleek suit, skinny tie, sunglasses and carry a black leather briefcase. George Wing’s direction to John Thorp was that he wanted the “Dussenberg” of airplanes, and the Derringer is indeed both a true work of functional art and an engineering marvel not seen in other light aircraft.  Sadly, ultra high-quality machines like Dussenbergs and Derringers do not always ensure business longevity.  Nonetheless, I’m now a lifelong fan and the Derringer serves as the apex of light aircraft design.