Airpower Magazine, Volume 7 No. 3 May, 1977
The engineering side -- pros and cons.
It is surprising to discover how sensitive and controversial the Channel Wing is today, after all its many years in the public eye. In an attempt to determine what the real merit of the Channel Wing is, I went to several engineers who had taken part in the testing and development of the device over the years. I interviewed participants of three different kinds. First were government representatives who had either conducted or interpreted the official tests. Second were engineers who had seen development potential in the channel wing, and who had a positive interest in its commercial success. Third was an engineer who was completely objective having neither a financial or government interest.
Because of the controversy, and because some legal action may still be forthcoming, I've been asked not to name the participants involved.
The Pro Side: Proponents of the Custer Channel Wing say that first of all, the true capabilities of the idea were not susceptible to test because appropriate engineering theory had not yet been developed to explain its demonstrated performance. In other words, the airplane was physically doing things for which aerodynamic formulas had not yet been evolved at the time of testing. Such formulas have since been developed, and further testing could be done in a more scientific manner.
Because adequate theory was lacking, the CCW was tested for features and modes of flight which were in reality peripheral to its main intent, simply because there was theory to test these items.
The pro-channel wing faction maintains that the channel wing's pusher propeller arrangement not only forces circulation over the airfoil, taking advantage of the Bernoulli principle, but it also minimizes loss due to reverse flow around the trailing edge, and then across the ventral surface.
The NACA tests, they say, erroneously failed to reveal that the principal source of lift is due to the increased velocity in the channels, and further, the tests should have highlighted the findings that the static lift exceeded the weight of the test vehicle. This basic fact underlies the most salient advantages of the Custer Channel Wing, its simplicity, and its ability to operate in the STOL mode without expensive high lift devices.
The initial cost of the Custer Channel Wing aircraft -- of any type -- is probably slightly greater than a conventional aircraft of the same type, but less than that of an equivalent STOL aircraft using flaps, slots, etc. Its advantage stems from the fact that its operating costs would be far lower than those of the STOL alternative, because of the lessened maintenance requirements. Its greatest advantage, however, lies where it can be employed in helicopter operations, i.e. those situations in which helicopters are presently used, but with suitable modification in technique or landing area, a CCW could be substituted. The reason for this, of course, is the horrendously high cost of helicopter operation.
The CCW could be used for larger aircraft, and with jet engines. The increased drag of the channel wing undoubtedly would reduce top speeds, but in the correct application this would not be significant. "Correct application" includes STOL airline transportation over relatively short stage distances; use in remote areas where the ability to fly in and out of short airstrips with heavy loads is important, or where revenues dictate against the use of a high operating cost vehicle.
In sum, the CCW proponents say that the concept provides an economic, efficient solution for certain applications that are not presently met by conventional STOL aircraft or helicopters. continue...