The Republic Seabee amphibian was one of the most unusual airplanes to appear on the post-World War II general aviation scene. It was designed as an affordable all-purpose sport aircraft for transportation as well as a broad spectrum of recreational purposes. The sea/land capability not only provided a broader selection of travel options but also remote access to fishing, hunting and many sporting activities.
The design of the Seabee originated as a private venture of Percival H. "Spence" Spencer who flew the all-wood original prototype in 1941. Spencer had designed a number of airplanes in his earlier years and teamed with Vincent Larsen in 1937 to produce a forgettable amphibian known as the Spencer Larsen SL-12. Spencer decided to strike out on his own and, on Long Island in 1940, he developed a more practical design, the Spencer S-12 Amphibian Air Car. It was a two-place, side-by-side amphibian of all-wood construction, with flat sheet plywood shaped to fit the bodylines. The wings and tail structures were fabric covered with wood spars and ribs. It was powered by a 110 hp air-cooled Franklin engine, mounted in a pusher configuration powered the aircraft. The tail was mounted on a structural boom and the wings and tip pontoons were strut-braced. Spencer demonstrated the airplane and intended to go into production, but World War II intervened.
After the war, Spencer worked for Republic Aircraft which had begun to look for a commercial design for sport flying. Some of his colleagues at Republic remembered his Air Car design and Spencer soon sold the rights to Republic in December 1943. He was assigned to help convert the airplane to all metal. Along the way it became a three-place airplane with a bigger engine, metal hull from nose to tail, a tapered smooth skin cantilever wing and single strut-mounted wing floats. The airplane was renamed the Republic RC-1 Thunderbolt Amphibian. It was a good performer but the construction was very labor intensive and the costs began to skyrocket. The original intent was to market the airplane for $3,500 but when the price estimates reached $12,000, the aircraft was redesigned.
The aircraft became a four-place airplane for better utility. The rear seat in the RC-1 had been restricted to one passenger because the partially retracted main wheels were located in wells that protruded into both sides of the rear seat area. To provide space to seat two back seat passengers comfortably, the wheel retraction wells were eliminated and the main landing gear rotated up parallel to the hull. The design increased drag on the aircraft slightly but reduced manufacturing costs and provided a fourth seat. The re-designated RC-3 Seabee was now a model of simplistic lightweight construction in labor and tooling costs. The rivet count, for example, was reduced from 9,650 to 3,440. The fabrication and assembly time was reduced from 2,500 man-hours to a phenomenally low 400. The design changed from a tapered to a straight wing with simple spars and end ribs, and the inclusion of beaded structural skins for the wings and tail surfaces. The hull became nearly a full monocoque bulkhead and skin construction, thus eliminating the usual multiplicity of stringers and intercostals. The wing tip floats were made in two hydro-pressed longitudinal halves that were machine-riveted along their exterior seams.
Operationally, the Seabee was an extremely rugged and versatile aircraft that could take harsh treatment, but it required high maintenance. It had excellent cabin accessibility and a cavernous interior with exceptional visibility. The water handling was outstanding but it was considered less comfortable in land operations. Its in-flight performance was adequate, cruising at 105 mph, but with somewhat heavy flight controls. As a victim of the collapsing market, the projected goal of producing 6,000 Seabees was terminated at 1,076 aircraft in 1948. J. K. Downer of Saginaw, Michigan purchased the design certificate in 1956 and provided spare parts for the remaining Seabee owners. Still underpowered, its owners resorted to several engine conversions, and the United Consultant Corporation marketed the Twin Bee which had two 180 hp Lycoming IO-360 BID engines. This venture was not too successful because of high initial purchase and operating costs. However, many Seabees are still flying and they remain popular with seaplane pilots.
RC-3 Seabee, N6709K, came off of the Republic production line in June 1947 as serial number 992. Robert N. Stiner and Alexander D. MacCallum purchased the airplane on September 16, 1969 from JUL Incorporated of Hato Rey, Puerto Rico. With his son as a passenger, he personally delivered the aircraft to Hyde Field, Maryland, on September 6, 1984. It had logged 835 flight hours and came equipped with the 215 hp Franklin engine and the optional Hartzell controllable and reversible propeller, with aluminum blades. The ability to alter the blade pitch, or angle, of the propeller increased performance at takeoff and cruise and facilitated maneuverability of the water.
In 2001, Stiner donated the aircraft's original propeller blades made from Hartzite, an early type of composite material consisting of fabric impregnated with plastic that Hartzell introduced to offset the effects of water erosion. Over the years, owners often replaced them with aluminum alloy blades because the Hartzite blades began to disintegrate when the laminate coating wore off.