New amphibians rely on historic designs

loeningcoa1It was recently reported that an aging fleet of seaplanes is prompting several companies to come forward with new or renewed seaplane designs.

Aircraft mentioned include Viking Air’s new-production Twin Otter, the reborn Grumman Goose by Antilles Seaplanes, and the new design Dornier Seastar amphibian. The Viking website (VikingAir.com) refers to the new-build Twin Otter as “combining the best of history and design with modern technology.”

Historic indeed, as this leads one to ruminate on the many amphibious designs during the golden age of the 1920s and 1930s.

EARLY DEVELOPMENTS
The idea of an aircraft that would fly from both land and water was brought out as far back as 1876 when Pénaud patented a design for an amphibious two-seat monoplane, which was never built.

The first practical step was in 1907 when the Wright brothers fitted a canoe between the runners of a Flyer Wilbur flew in New York City.

The Curtiss Triad was probably the first demonstration of an amphibious aircraft. A basic Curtiss Hydro Pusher was modified by the addition of retractable wheels mounted on a float. Though not a practical machine, it was successfully demonstrated by taking off and landing on hard-packed sand at San Diego on Feb. 26, 1911.

The first aircraft designed as an amphibian was done for the Navy by Sperry in 1919. In 1920 the Navy had the Elias brothers in Buffalo outfit a Curtiss MF flying boat with amphibious landing gear. In 1924 Curtiss introduced the Crane, an amphibious version of the Seagull flying boat based on the Elias conversion.

LOENING
Probably the most famous of the early amphibians was the Loening (pictured, above).

The Loening Amphibian was not only the first tractor amphibian in the United States, but also the first successful amphibian with a production that spanned over 10 years. It was used by the U.S. military, early airlines and private owners.

The development of the inverted form of the Liberty V-12 engine made possible a new form of amphibious aircraft. The high center-line of the engine allowed clearance for a propeller above a central float that, in turn, made possible a tractor amphibian.

Based on these ideas, Grover Loening proposed to the Army that his company be given an order for a completely amphibious airplane with a retractable landing gear. In the proposal Loening guaranteed that the new plane’s performance would exceed that of the DH-4s then in use.

Successful tests showed the Loening to be 10 mph faster than the DH-4, with a higher ceiling and slower landing speed. This success led to further military orders, while the addition of a passenger cabin in the fuselage led to production for civilian use.

The reliability and versatility of the Loenings made many exploration flights possible, including the Byrd-MacMillan expedition to the Arctic in 1925, the Army’s Pan-American Good Will Flight of 1926-27, and the Navy’s Alaskan surveys in 1926 and 1927. Airlines that used the amphibians included Gorst Air Transport, Alaska Southern, Koehler Aviation and Western Air Express.

SIKORSKY
During the 1930s, the word “amphibian” brought to the public’s mind the name Sikorsky.

In 1926 Igor Sikorsky began the development of his line of amphibians with the S-36. It marked the first original amphibian design since the Loening. This design also set the standard with a short cabin hull and tail surfaces mounted on twin booms supported by outriggers. Powered by two 300-hp Wright J-6 engines, it could carry a pilot and six passengers at a speed of about 120 mph.

The next Sikorksy amphibian would prove to be the most popular of the series. This was the 10-place S-38 capable of 130 mph. It found instant success, being used in quantity by Pan American and other airlines. The S-38 was so popular that the company had to move to a new, larger factory in Stratford, Conn.

Three more basic amphibian designs would be brought out. Altogether there were 25 variants of these amphibians produced. (Note: Sikorsky preferred the spelling “amphibion” and used it in advertising.)

GRUMMAN
When the Loening company merged with Keystone and moved to Pennsylvania, three senior employees, including Leroy Grumman, decided to go into business for themselves as the Grumman Aircraft Corp.

The Grumman JF Duck, produced for the Navy, was the company’s first amphibian. The design was a descendent of the Loening amphibian with the main float part of the fuselage. The Duck went into production in early 1934 with an order for 27. These aircraft would become an important and hard-working part of the Navy and Coast Guard.

The first civil amphibian created by Grumman was the G-21 Goose, a six- to seven-place twin engine monoplane.

It was designed to meet the needs of wealthy aircraft owners and business men looking for a replacement for the Loening amphibians. Before going out of production in 1945, 345 G-21s were produced. Some saw service with airlines into the 1950s and 1960s.

Dennis Parks is Curator Emeritus of Seattle’s Museum of Flight. He can be reached at dennis@generalaviationnews.com.

Comments

  1. A note from author Dennis Parks: Good catch, the number of 200 came from a contemporary account. (Probably marketing hype). Jane’s says 120 mph for the S-36 and a Sikorsky sales brochure for the S-38 lists its top speed at 125 mph.

  2. Everitt duPont says:

    I think there must be a misprint in the article about the Sikorski’s S 36 Amphibion that could travel at 200 mph with six passnegers. I think it is more likely it should have said travel 200 miles with six passengers. At that time 200 mph was unatainable by most aircraft in level cruise.

Speak Your Mind

*