The advent of the light twin

With the end of the war in Europe in May 1945, the prohibition on the production of civil aircraft was rescinded. Many articles published that year were harbingers of the post-war boom expected for the general aviation industry. Indeed there was a huge boom in production — general aircraft production went from 1,946 in 1945 to an unbelievable 33,254 in 1946.

This was truly the golden era of light aircraft production. But it was a short-lived one as the market rapidly went sour as returning GIs and the public were struggling with other demands. Sales in 1947 fell to around 15,515 airplanes, and by 1949 had plunged to 3,500.

But out of this post-war bust would come a boom in a new category of general aviation aircraft — the light twin.

At the end of the war, almost a dozen multi-engine light plane designs were in the works. Some aimed at the new feeder airline market and others for what Flying Magazine called the “Super Personal Plane” providing the owner with the added performance and safety of two engines.

The new light-twin engine offerings that pioneered the field were the Aero Design Commander, the Beech Twin Bonanza, the Piper Apache, and the elegant Cessna 310.

AERO DESIGN COMMANDER

The Second World War was not over yet when a group of Douglas engineers meet with Ted Smith, project engineer on the A-20 bomber, to discuss his ideas for producing a new type of aircraft, a small, light twin-engined plane for the general aviation market. This was in December 1944. The group would start work on the project in their spare time and in August 1945, Smith resigned from Douglas to pursue his vision full-time, forming the Aero Design and Engineering Corporation.

The prototype, the Model 520, first flew on April 27, 1948, and became the forerunner of a long line of medium-sized, twin-engine aircraft. The first production model came out in August 1951. The first Aero Commander gained a lot of national publicity when it flew nonstop from Oklahoma City to Washington, D.C., with one prop removed. This demonstrated that the first generation of light twins did have abundant single engine power.

Using modern, slim flat-six cylinder piston engines, the aircraft had a lot less drag than the pre-war, radial powered twins, such as the Cessna T-50 and Beech 18. It had lots of interior room, easily seating five, and with its pair of 240-horsepower, geared flat-six piston engines, the 520 could cruise along at about 200 mph.

BEECHCRAFT TWIN BONANZA

The Beechcraft Model 50 Twin Bonanza was a small twin-engine aircraft designed by Beechcraft to fill a gap in the company’s product line between the single-engine Model 35 Bonanza and the much larger radial engine Model 18. After its introduction in 1952, it became the first light twin to be constructed in quantity.

The Twin Bonanza was about 50% larger than the Bonanza, had more powerful engines, and was significantly heavier. A twin-engine derivative of the Bonanza was developed in an effort to improve performance, load capacity and provide twin engine safety. The Twin version was not a true derivative of the single engine Bonanza, as its cabin was longer and wider but it did use some of the tooling for the single engine Bonanza.

The Twin Bonanza featured 260-hp geared Lycoming engines, full feathering props, and wide tricycle landing gear with steerable nosewheel. It had a spacious cabin with two rows seating six people.

It first flew in November 1949, a rapid development, having only begun in April of that year and only three years after the single engine Bonanza was announced. The Model 50’s type certificate was awarded two years later with production beginning that year.

Its availability to the general aircraft market was delayed as the US Army took almost the entire production for 1952 and 1953 due to the Korean War.

Production of the Twin Bonanza ended in 1963, but the aircraft continued development as the Model 65 Queen Air and the Model 90 King Air.

PIPER APACHE

The introduction of a low-wing, all-metal light-twin by Piper Aircraft was a step up from its ubiquitous, rag and tube, high-wing Cub. In 1948 Piper Aircraft purchased the assets of the Stinson Division of Consolidated Vultee, which included about 200 Stinson Voyagers, Station Wagons, and drawings for a proposed “Twin Stinson.”

The test version of the Stinson design flew in the summer of 1952. The twin-tailed, fabric covered, four seater with fixed tricycle landing gear was shown to be underpowered with 125-hp Lycoming engines. Flight test also showed handling problems. The airplane was redesigned from the rear of the cabin backwards and the engines replaced by 150-hp units with constant speed props, while retractable landing gear was also fitted. This became the basic Navajo and type certification was issued in December 1953.

In 1952 it was announced that the sale price was tentatively set at $25,000 but went to the market later with a price of $32,000. Howard “Pug” Piper, responsible for new product development, was quoted as saying that “A good price could help us get away from the Cub image.” At the time a Cub could be had for $3,500.

The asking price for the new Piper twin was a good one as the Aero Commander and Twin Bonanza were going for around $45,000. The Apache became the most popular of the early light twins with almost 2,500 registered by 1964.

CESSNA 310

The last of the pioneering light twins to hit the market, the Cessna 310, looked like it was flying fast while it was parked on the ramp. It must have gained many buyers though its sleek looks.

When the Cessna 310 was launched in 1953, it was the first Cessna twin since the T-50 Bobcat of World War II. The 310 was a revelation compared to the T-50. Whereas the T-50 was of fabric covered steel tube construction powered by seven-cylinder radial engines, the 310 was all metal monocoque construction powered by six-cylinder flat horizontally opposed engines.

An innovation was the use of wing tip tanks, which permitted the wing space normally used for fuel tanks to be used to house the main landing gear. This allowed for much smaller, more streamlined engine nacelles. On a couple of 240-hp O-470 Continental engines, the new twin could make 220 mph, compared to the 175 mph of the T-50.

The 310 would gain national attention when Kirby Grant on his Sky King TV show switched his flying mount from a Cessna T-50 Bamboo Bomber to the slick 310 in 1958. Named Songbird II, it was the second production 310B, which was provided by Cessna at no cost to producers. Before going out of production in 1981, nearly 5,500 310s would be built.

Credit must be given for the foresight shown by these manufacturers of these light twins as they were developed during a period showing a deep decline in light aircraft sales. Not only did they have to show faith in their designs, but had to bear the cost of new tooling and production lines for the new class of aircraft. In Piper’s case this was estimated at more than $800,000.

Indeed, the light twin was a new category of general aviation aircraft that pioneered a new market. During the 1950s, an interest in this new type of general aviation aircraft developed and rapidly grew. In fact, interest grew so rapidly that most of the general aviation companies produced an entry in the light twin category. By 1964 there were nearly 6,000 light twins registered in the United States.