The Model 560 was the second Commander to be placed into production by the Aero Design & Engineering Company at Tulakes Airport (later renamed Wiley Post), in the Oklahoma City suburb of Bethany.
A total of 80 examples (serial numbers 151 through 230) were built between May 1954 and June 1955. Of these, 39 were initially certified in 1954, and 41 in 1955.
A factory document describes the Model 560, under Wing Drawing 5170000, as “certified on May 28, 1954. This Model is similar to the Model 520. The following alterations were incorporated: a) Gross weight increased to 6000 pounds; b) Lycoming GO-480-B engines were used; c) swept vertical stabilizer was installed; and d) structural modifications to the wing, landing gear, fuselage, vertical tail, and primary controls.”
The Model 560 was indeed certificated on May 28, 1954 under Type Certificate 6A1, which says “Same as Model 520 except for increased weight, increased horsepower, and swept tail. Revised model incorporates structural modifications to the wing, landing gear, fuselage, vertical tail, and primary control systems.”
The first 65 examples left the factory with 270-hp Lycoming GO-480-B engines, while the remaining 15 had the GO-480-B1C. The -B1C variant, not certificated until February 8, 1955, had an angle generator drive, and dual generator and vacuum pump drives. The first four examples used the 90-inch-diameter two-bladed Hartzell HC-82X20-2A/9333C-3 propeller, but three had three-bladed propellers installed quite soon after delivery. The other 76 examples were delivered with the 84-inch-diameter three-bladed Hartzell HC-83X20-2 series propeller hub with 8433 model blades.
The factory had conducted tests in June 1954 on a Model 520 with two-blade propellers and a Model 560 with three-blade propellers, and it was determined that the three-blade ones materially reduced the noise level in the cabin area and the level was more constant throughout the cabin. With the two-blade propellers it varied as much as five decibels over the cabin length. Using three blades resulted in the tips being 3 inches further away from the fuselage.
Like the Model 520, the 560 had exposed exhaust augmenters, but now had the familiar swept tail. Model 520 Serial Number 88 actually served as a prototype for the Model 560 and the 560A that followed, and may have been used in developing the 680 “Super” Commander. Having been damaged and the wings wrinkled, it couldn’t be delivered to a customer and was turned over to Engineering. There are photos of “Old 88” with the swept tail that has the striping and logo running downhill instead of horizontal. Also, like the Model 520, the 560 had main landing gear torque links, or scissors, which faced aft.
The 560 was the last model to be certified at Bethany until 1973. The factory R&D facility was opened at Norman-University of Oklahoma Westheimer Airport during September 1954, and all certification work was done at that facility up to and including the Model 685 in late 1971. Starting with the Model 690A all static testing, fatigue testing, and flight testing then returned to Bethany.
Barry Collman’s lifelong interest in airplanes began when he was growing up in a house located underneath the downwind leg to busy Northolt aerodrome, an R.A.F. base near London-Heathrow airport. As a young teenager he discovered airplane “spotting”–hobbyists’ observation and logging of aircraft by make, model, and registration number. The hobby began to grow into a passion as Collman joined a club of like-minded spotters. At one point he purchased a copy of the January 1966 U.S. Civil Aircraft Register, and thumbing through it came upon the Aero Commander. He was hooked. Eventually he acquired every available FAA microfiche file on Commanders, and since 1995 has made annual pilgrimages to Oklahoma City to sift through FAA records. He now has a database with more than 96,100 records as well as a collection of negatives, slides, photographs, digital images, magazines, brochures, knick-knacks–and a very understanding wife. This series on Commander production history originally was written for the Twin Commander Flight Group, of which he is an enthusiastic member.