Engineers at the Georgia Institute of Technology Research Institute in Atlanta, U.S.; are quietly researching the possibility of applying a Channel Wing Configuration technology to the designs of future aircrafts platforms. The Channel Wing Configuration, when implemented on the wing design, would give the aircraft the ability to generate a high volume of lift, which could open the path to many design possibilities. The idea of configurating the wing design to be able to generate more lift has been around since the birth of aviation early in the 1900s. Preliminary studies by aviation engineers on the subject in the mid-to-late 1910s resulted in experimentation with various form of wing configurations and settings. Eventually, advances on airframe deign and a premium on engine performance took center stage, thus neglecting the concept of wing modification to achieve greater lift. For years, research into a greater lift-generating wing design was shaped by traditionalist aviation engineers and designers. Thus, radical new ideas were never fully pursued, that was until a brilliant Maryland inventor came forward with a new concept in 1935.
Willard Custer was one of the first true champions of the lift principal called aero physics. He stated that the amount of lift generated by any aircraft is determined by the speed on which the air flows over the wing, not solely on the speed of the wing moving thru the air as articulated by many. If a wing configuration were to be designed with deep channels, dropping like a couple of “smiles” under the propellers; then the aircraft would generate more lift with it than a conventional wing configuration. For Custer, the idea was simple enough. An aircraft can generate lift with zero forward speed utilizing the engines to provide the necessary airflow to sustain the plane in the air, thus achieving an impressive amount of Short Take-Off and Landing (STOL) capability. Additionally, with the channel wing shape, the engine thrust is propelled downward, providing the aircraft with the ability to perform short take-offs, and, as an added bonus; maintaining air control at relative slow speeds. The idea that an aircraft can achieve virtually vertical take-off and landing capabilities by re-designing its wing configuration a was radical concept in the late 1930s.
The aviation community did not think much of Cluster’s Channel Wing Concept. That’s the risk someone takes when propelling radical new ideas. Nevertheless, Custer marched on. In the summer of 1943, his first aircraft design with channel wings was demonstrated to the United States Army Air Forces in Maryland. Immediately, the CCW-1, as the plane was designated, was a media darling. Stories of this strange-looking aircraft, nearly hovering over the ground, fascinated many in the country. Unfortunately, the US Army was not one of them. They branded the CCW-1 impractical because of the extreme nose-up attitude requirement for landing. There were also issues about the survival of the CCW-1 in combat. Test flights showed that if one of the engines were to be lost, the pilot could not maintain effective control over the aircraft.
Despite the setback, Custer persevered, and in the fall of 1959; he presented his new aircraft, the CCW-5 to the Marine Corps. Again he was turned down. Mainly, for the reasons stated in 1943; the concept seemed to hit the wall. No major research was invested on the channel wing concept until 1995, when the idea was resurrected by Dennis Bushnell, Chief Researcher at NASA’s Langley Research Center in Virginia. For years Bushnell mulled over how to fit an aircraft in tight locations off the ground. He researched the accepted principals of direct thrust and rotary wings, but they were not able to produce the desired results, as recent experimentation had shown. But Bushnell had an ace. For years he had known and studied the work of Custer on the Channel Wing; and he wondered if a combination of control circulation, a method from which lift is generated utilizing jet of air to improve the aerodynamic characteristics of the wing, and the channel wing, could be the answer. Either of these systems, by themselves, could not provide the aircraft with the necessary characteristic he desired, but combining the two was seen by Bushnell as the way forward.
A new research program commenced in 1999 and lasted until 2004. The research focused on the Coanda Effect, named after its founder; Romania researcher Henri Coanda, who in August 1910 discovered that hot gases exiting a jet followed the contour of the plates installed to deflect it. Circulation Control follows a different path. Simply put it, circulation control works when compressed air is directed over a curve or leading edge to generate greater lift capacity. Researches believed that circulation control, could in the future rend obsolete moving surfaces on aircrafts. The next step in the developmental process for Circulation Control is the replacement of mechanical lift augmenters with air hoses to make the aircrafts lighter, quieter and maintenance friendly. For all of this to take effect, surface system needed to be introduced, and here is where the Channel Wing Concept comes into play.
Current computing systems used to measure fluid dynamics of aircrafts’ surfaces had established the feasibility that a Channel Wing configuration with enhance Circulation Control, could produce a serviceable and stable super-STOL platform. Wind tunnel testing and computer animations had confirmed the Channel Wing design payoffs in ways that Custer could not have done in his time. Custer clearly understood the airflow needed to generate lift could come from two different sources: the engine or the airframe forward motion. What he lacked was an understanding of what happened to the air stream once it hit the channel. The end result is turbulence. This is why both the CCW-1 and 5 failed to achieve major air-control properties. At low speeds, the flow of air is detached form the traveled surface; leading to the aircraft to lose differential pressure that is the cause of lift. At Custer’s time, there was no method accurate enough to calculate when this effect comes to play or how to design an aircraft that used this effect in its advantage. The solution: Circulation Control. One of the most challenging arenas for the CCWs models were the high angle of attack that the aircraft needed to be flown, a dangerous proposition because the pilot will temporarily loss the ability to see over the plane’s nose. Another problem was the lost of an engine. If the aircraft were to loss the use of one of its engines, the aircraft will be subject to high stall degrees and rolls, without the necessary energy to compensate for them. Circulation Control can solve this problem.
At present, Bushnell and his team had been pressing for sometime to design and aircraft that incorporates both concepts, but like Custer before, without much success. Skeptics’ rapidity pointed out that all the research data done during the past five decades had failed to produce a serviceable aircraft design, thus leading them to the conclusion that the concepts are incompatibles. The Channel Wing concept may need to wait until advances in technology can undisputable show that an airworthy aircraft can be achieve; but the Circulation Control concept is already been use by various countries in the design on unmanned air vehicles. Even a naval application was found for the concept. Submarines could use jets instead of conventional dive planes and rudders to change aspect ratios.
Custer’s idea was years ahead of his time, and seems today, that is still ahead of us. Further research and data collection maybe needed, but with the current military situation, a premium is been place on the ability of aircraft to perform short take-off and landing s procedures, its only a matter of time before the next great engineering breakthrough comes along and Custer’s idea will probably be at the center of it.
– Raul Colon