A monoplane and a half

The Buhl company was fond of calling several of its cabin aircraft Airsedans.

Designed with significant differences, the way to distinguish the various Airsedans is by their model number and appearance.

The CA-6 refined earlier Airsedans, and made distinct strides into the sesquiplane world. Its lower wing was more of a vestigial suggestion of a lifting surface than a full-fledged wing.

Sesquiplanes enjoyed a moment in the sun as designers grappled with the robust structural truss integrity of biplanes versus the lower drag of monoplanes that were in ascendancy in the late 1920s and into the 1930s.

Sesquiplanes, effectively a “monoplane and a half,” as described by civil aviation historian Joseph Juptner, used an abbreviated lower wing to enable bracing, while keeping overall span short, and reducing drag below that of a full-bore biplane.

The Buhl CA-6’s upper wing spanned 40 feet, the lower wing was only 26 feet and an inch. The upper wing had a constant chord of 81 inches, the tapering lower wing had a mean chord of 46 inches. Wing area of the upper was 239 square feet, while the lower wing area was only 76 square feet.

The CA-6 Airsedan got a boost into the history books when colorful pilot Nick Mamer and copilot Art Walker flew a CA-6 loudly emblazoned with the name Spokane Sun God, and showed how a transport could fly from Spokane to New York and back to Spokane without landing.

Mamer and Walker relied on extra internal gas tanks and, importantly, aerial refueling from a hose-trailing support aircraft, as well as gasoline-laden milk cans lowered by rope. They tallied 11 aerial refuelings as the duo covered 7,200 miles in 115 hours, or just about five days, starting Aug. 15, 1929.

The Buhl CA-6 also could be operated as a floatplane, and CA-6s earned a good reputation in the rugged northwestern U.S. and into Canada, where these sesquiplanes hauled freight and passengers.

Empty weight of the CA-6 was 2,478 pounds. With 100 gallons of fuel tanked, the payload was 890 pounds.

The radial Wright J6 engine gave the CA-6 a top speed of 140 miles per hour, while cruise was 120 — both good arguments for the streamlining effects of the sesquiplane configuration. The CA-6 landed at 45. It could attain 900 feet of climb in the first minute of flight from sea level, and had a service ceiling of 17,000 feet.

The fuselage was welded steel tube, skinned in aluminum back as far as the two entry doors, and fabric-covered aft of the doors.

The CA-6 came standard with an inertia starter. A metal propeller, plus navigation lights and wheel brakes, also were standard. The cost of this machine was $13,500 at the Buhl factory airfield in Marysville, Michigan.

The name Buhl has long been prominent in the Detroit area, where the family grew several businesses and created wealth starting in the 1800s.

The company built about 185 aircraft of several types before dissolving in 1932. Of these, probably just under two dozen were CA-6 Airsedan models.