| Sport Aviation May 1988 | https://www.angelfire.com/ks2/janowski/other_aircraft/AG14/SA.html |
Baby Twin-BoomerThe Anderson, Greenwood AG-14 was one victim of the great post-war bust.By Mark PhelpsLocate a need in the marketplace and fill it with your product. The principle is as old as the art of invention. At the close of World War II, airplane designers saw an obvious need for new light airplanes to satisfy the flying lust of returning military pilots. The automobile was old news, further stifled by five years of frozen design in which everything that rolled off the assembly lines was olive drab. In the modern era of peace and prosperity, everyone would fly - a spanking new airplane in every garage. Two designers had a head start on the pack, having come up with their concept even before they went off to Boeing to do their part for the war effort. Their personal airplane was easy to fly, safe and most important, as pleasant a way to get from place to place as any car. It was quiet, smooth and provided an excellent view of the unfolding landscape. It also looked unusual, a twin-boom pusher with tricycle gear and a low-slung fuselage pod incorporating lots of glass. Pilot and passenger sat side-by-side on a bench seat, steered on the ground with the control wheel and stopped with a single brake pedal just like in the family Buick. Yes, it was more expensive than a car, all of $4,200 GI dollars, but after the war there would be lots of money for every family. This generation's historical task had been completed at tremendous cost and now it was time for the survivors to relax and enjoy the good life. But people were to find that life wasn't so simple. Even the tragic price paid by a generation did not guarantee peace and prosperity. To those who designed airpianes, the bitter pill was that the automobile was indeed alive and well - still first in the hearts of the American family. The fallout of the post-war aviation bust saw several clever prototypes relegated to aero-trivia. There were only five of the funny little pushers built and one of them has found its way to the EM Aviation Museum - a fitting representative of the promising contenders that never got a start in the aviation marketplace. Many of those stillborn airplanes were marvels of engineering that simply came along at the wrong time - a time that had seemed to everyone to be so right. It was in 1940 that a young Marvin Greenwood left the Southern Aircraft Company in Texas and joined his brother-in-law, Ben Anderson, to form a small company in Houston. Greenwood was an aeronautical engineer with masters' degrees from Rice Institute in Texas and Cal Tech in California. Ben Anderson had formed a successful accounting firm that is still in business today. The new company was called Anderson, Greenwood Company, or AGCO, and its first project was the AG-11, a two-place, tandem, low-wing monoplane with retractable landing gear. Early in 1941, however, the military began rationing aluminum among aircraft producers and independent aircraft production became an impractical idea. Besides, the large aircraft manufacturers were dangling big salaries in front of people with aircraft production experience. Both men joined Boeing in Seattle for the duration of World War 11 and Marvin Greenwood became assistant chief engineer on the B-29 program. After the war, the two men filtered back to Houston and AGCO was rekindled at the old Sam Houston Airport. Using their personal funds, the men developed a new light airplane based on a design philosophy that might sound familiar today but was a new idea back then. In Document 227 of the Institute for Aeronautical Sciences, Greenwood laid out the design goals. The machine was to be built around environmental considerations of the occupants, and the engineering was to serve human needs, not the other way around. Instead of trying to build an airplane that would fly faster, farther or cheaper, ease of operation and creature comforts filled the front engineering burners. Greenwood figured that the one sense out of five that airplanes served positively - sight - should be paramount in the design. Hearing, feel and touch were all negatively affected by airplane flying (taste remained neutral). The theory - maximize the effect on an occupant's sense of sight while minimizing the other three. It became clear that the noisy, smelly and shaky powerplant belonged well insulated behind the passenger compartment where it wasn't blocking the view. Twin booms added a measure of safety, disallowing an easy misstep into the whirling propeller. Simple. Of course the pusher design was not new. Besides the Wright Flyer and the early Curtiss machines, the configuration was found on more modern airplanes such as the Stearman-Hammond (later the Kaiser-Hammond), the Wheelair III and the Republic Seabee. Like the designers of these machines AGCO faced the difficulties imposed by wing-body interference, cooling and balance. These were some of the engineering hurdles to be overcome en route to the ideal personal airplane.
Wind tunnel tests determined that a shoulder-high wing was ideal for minimal wing-body airflow separation that is intrinsic to the pusher configuration. It also provided the best visibility. The Model 14's wing also had the highest aspect ratio (9.6) yet designed for a personal airplane. The all-metal, monospar wing relied on internal webbing and its thick airfoil for strength. An auxilliary spar well aft carried the flap and aileron front hinges.The thick airfoil ailowed the engineers to use fewer ribs and lighter-gauge skin for lower weight, while improving stall characteristics - although at some expense to top speed. Double-opening split flaps were tried but later discarded in favor of simpler single-surface flaps because the difference in minimum controllable airspeed proved not enough to warrant the added complexity.
Mounting the engine close to the center of gravity presents some balancing problems, usually associated with stall behavior. Without that large amount of weight pulling the nose down, many textbook aeronautical design principles fly out the window. The Bell P-39 Airacobra with its mid-fuselage Allison engine is a good example. Since the passenger compartment must be placed off of the CG, variations in crew weight necessitate wide limits of trim excursion and light stick forces in pitch. In the stall regime, the pusher design tends to go into a flat spin. The Model 14 countered this tendency with a sharp seven-degree dihedral for directional stability. This also allowed placing the seating centerline closer to the CG, minimizing the trim problem. Additional dihedral effect was gained by shaping the wingtips with an upward slope to the bottom. The steep dihedral and limited elevator travel made the Model 14 virtually spinproof. Even when forced into an incipient spin by a skilled test pilot, the airplane would recover by itself after one turn, even if the pilot held the controls crossed to the stops. Another balancing act consisted of using a four-inch extension shaft on the propeller, allowing the engine to be mounted even closer to the CG. Cooling
AGCO's Jim Elder was instrumental in turning concept into aluminum. The body was built up from a keel beam with standard monocoque construction. The twin booms were built with a top pan and sides and bottom made from one bent up sheet with two W sections inside of each lower corner to increase compression strength. An intercostal piece with lightening holes was added at the midpoint of the inside of the boom to increase buckling strength of the sides. The back of the 44-inch-wide bench seat folds forward to reveal a spacious baggage compartment capable of holding 240 pounds, but not accessible during flight. In the machine donated to the EAA, the fire extinguisher is mounted in the baggage compartment - not really the best spot. The nosegear steers through the control yoke and a single pedal activates both hydraulic brakes. The floor of the Model 14 looks like that of a 194Qs sedan with the starter button mounted between the two rudder pedals and the brake pedal mounted to the right. Only the left boom has a rudder mounted on the vertical fin - and it's a small rudder at that. Model 14 pilots learned healthy respect for crosswinds as the steep dihedral required lots of aileron and, as in the Ercoupe, a quick transition to neutral before the yoke-linked, steerable nosewheel met the turf. The drill was to make contact with one wheel and make certain that the airplane had quit flying for sure before centering the yoke and letting the nosewheel down. The flaps are actuated manually with a two-position lever between the occupants. So AGCO had an airplane that seemed to answer its design philosophy needs with acceptable trade-offs. But how would it fly? Early one September morning in 1947, test pilot Ted Yarborough took off in the prototype for the first time from Sam Houston Airport. His verdict - not a bad airplane but the elevator was too small. Before dusk, it had been replaced with a larger surface and Yarborough had flown a total of five hours. He pronounced the airplane airworthy and even checked out Marvin Greenwood on that first day. Throughout 1948 and 1949 Greenwood quietly flew a concentrated test program and made several minor adjustments to the design. The small ailerons with steep deflection were replaced with longer-span surfaces that filled the space between flaps and wingtips. The horizontal stabilizer was moved from the base to the midpoint of the vertical tails. The cooling scoops under the wings were replaced with the latest NACA triangular ducts on the aft fuselage for drag reduction. The automobile-style safety glass windshield was replaced with a molded Plexiglas one-piece unit. Engine baffling was improved and the airplane was put on a diet, losing several pounds of empty weight. Late in 1949, AGCO decided to build five pre-production prototypes in the frozen design configuration incorporating all the improvements. The company also decided to replace the 85-hp engine with a Continental C-90-12FP (redesigned by Continental and designated P for "pusher") and a Hartzell ground-adjustable propeller. Boosting the output from the powerplant and cutting down on the empty weight gave the AG-14 acceptable take-off performance and a good speed range, although most pilots who have flown the AG-14 would have preferred an increase to 150 hp. In September 1950, CAA test pilot John Paul Jones of the Fort Worth Regional Office issued Type Certificate 4A1 to the Model 14. The airplane cruised at 110 mph with a top speed of over 120 mph. Initial climb rate was 700 fpm. Once airborne, handling was docile and the airplane was comfortable and fun to fly from the quiet, well insulated cabin. A pair of controllable fresh air vents were situated on either side of the nose-mounted landing light. The vents look like the machine gun fairings on a P-38, the better to scare lesser pilots out of the landing pattern. Entry and exit were easy and dignified through the car-type door on the right side of the body. The retail price was set at $4,200 to $4,500 - or about the price of a premium 1950 Cadillac. AGCO had done its work well, producing a safe, fun airplane that used the latest technology. The problem was in the marketplace. By 1950, there was virtually no light airplane market left. By then the large manufacturers had all but given up on light aircraft. Republic had dropped the Seabee, Lockheed had written off John Thorp's Little Dipper, the North American Navion was limping along and Grumman's "Kitten" project was figuratively drowned in Long Island Sound. The traditional lightplane manufacturers such as Piper, Aeronca and Cessna had reverted to prewar designs leaving new technology for dead. Only the Beech Bonanza defied the plague - a modern classic in 1946 that survives to this day. How could the AG-14 make its way in such a climate? It couldn't. Fortunately for the company, though, the government granted it a military contract to keep the doors open, perhaps as recompense for another rationing of aluminum during the Korean War. In fact, as a direct result of that contract, AGCO went on to become a prime designer and producer of high-tech valves for the space program and others - a role in which the company continues to prosper. The five pre-production AG-14s were the only ones ever built. In 1962 and again in 1968, licenses to produce the airplane (to be called the "Space Coupe") were granted to two companies in California, but the licenses both expired before any production began, although some parts were manufactured. That did not end AGCO's involvement in airplane design. In the early 1970s, the company purchased Bellanca Aircraft as a facility to produce the Aries T-250, an advanced four-place airplane designed by Marvin Greenwood. Timing was again the culprit as soaring interest rates (22% prime) doomed the design after about four were built. In 1983 another Greenwood design, an ultralight called the Witch, hit the market - again with little commercial success. The Greenwood Aircraft Company, producer of the Witch, was not directly affiliated with AGCO which is now a wholly owned subsidiary of the Keystone Corporation and employs about 650 people in Bellaire, Texas. So where did the five prototypes wind up? Obviously one is here in Oshkosh at EAA's Pioneer Airport. The others are a mystery. The EAA machine, N314AG, was originally N3902K (serial number 3) and we don't know much about its travels after leaving the Anderson, Greenwood factory the first time. The faded compass correction card has a Canadian registration number at the top of it so perhaps the airplane spent some time in Canada. One other AG-14 remains on the FAA register. N3903K (serial number 4) was purchased in June 1955 by the University of Mississippi Aerophysics Department which had a military contract for experiments in boundary layer control (BLC). The airplane spent several years as a test bed aircraft and later as a general transport airplane. As part of the testing, a duct was mounted around the propeller and that modification alone increased climb performance by 200 to 300 fpm, according to University test pilot Glen Bryant. At the conclusion of the test program the airplane was returned to its standard configuration and was flown to the EAA Convention at Rockford in 1961 by Melvin Swarzberg. Pictures of it appear in the October 1961 issue of Sport Aviation. Efforts to reach its current registered owner have not been successful so far. The University subsequently bought a second AG-14 that it totally reconfigured, removing the tail and wings and replacing them with composite units incorporating a ducted fan propulsion system. The front of the fuselage was also extensively modified. This airplane had increased so dramatically in empty weight and lost so much lift with the new wing that Bryant says he would only fly it very carefully if at all. His method was to gingerly climb out after a very long take-off roll, gently turn into the pattern with a shallow bank and perform his tests quickly in the pattern before landing as soon as possible. Most of the testing, which involved several different propeller designs, was performed on the ground. Both airplanes were sold to a broker in Oklahoma and the restored machine (S/N 4) is still on the FAA register. The whereabouts of the highly modified airplane (S/N 1 ) are a mystery, although the University had saved all the original parts for eventual restoration and they went with the airplane when it was sold. Serial numbers 2 and 5 are also missing, having last been reported in storage in parts unknown. Any clues? The normal survival rate for an aircraft type is about 50 percent. If 500 were built, then 250 will probably survive. The AG-14 seems to be right on the money for this ratio. Two survive with one question mark. Of all the fresh designs to come from the post-war era, this track record is not bad. Boyd Gallaher, former corporate pilot for the present Anderson, Greenwood Company flew the EAA's AG-14 from its last home in Houston at the parent company to Oshkosh for donation to the Museum. He made the trip with his wife in one day with three fuel stops. Like all pilots who flew the AG-14, he would have liked a bit more horsepower, especially for take-off and climb, but overall, he likes the little airplane. "It was a very stable and friendly airplane to fly," he says, "and, oh, what a view! A great way to see the countryside on a sunny day." It sounds like the answer to a designer's dream of the perfect personal airplane. Captions:
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