Sep 132011
 


The US Navy received many unsolicited aircraft proposals during the 1930’s, a time when defense dollars were scarce and aircraft manufacturers were especially desperate to land contracts. One of the more interesting proposals from this era is the Lee-Wendt “Amphibion” Model WA-22, a handsome design for a high wing monoplane amphibian from 1938 that featured extensive wing-fuselage blending, an advanced feature for the time. Though the Amphibion was never built, the aerodynamic blending it pioneered has become a common feature on many modern aircraft. The following description of the study is based on material found in Navy records at the U.S. National Archives.

The Amphibion was the product of Lee-Wendt Aircraft and Stout Engineering Laboratories. Though little is known about the former, the latter was a small Detroit-based company run by William B. Stout, the man behind the Ford Trimotor. The Amphibion’s origins can be traced back to the Model WA-14, a smaller proof-of concept study of similar configuration. The performance estimates of the Lee-Wendt Amphibion, Model WA-22 were based on tests of a 1/16 scale wind tunnel model of the Model WA-14 in the University of Michigan wind tunnel, the results of which were submitted to Lee-Wendt Aircraft on February 15, 1937. A study of the longitudinal stability of the Model WA-22 was also made based on these results shortly thereafter. The general specifications and performance characteristics for the Lee-Wendt Amphibion, Model WA-22 are shown in the gallery above.

The Model WA-22 was powered by two in-line Vee-type 1,150 hp Allison engines mounted on the upper surface of the wing in well-streamlined nacelles. An extension shaft at the rear of each engine drove a three-blade pusher propeller. The maximum rated power of each engine was 1,150 hp at 2,950 rpm, while the cruising rating was 900 hp at 2,300 rpm. In both cases, the power was assumed to remain constant from sea level to the critical altitude of 20,000 ft. The propellers were 10 ft. 6 in. in diameter and were assume to be of the two-position controllable type having a high pitch setting for take-off and climb. Propellers were gear-driven so as to operate at one-half crankshaft speed.

Though the Model WA-14 was smaller in scale, both designs had practically the same size hull, wing fillet and tail unit when compared on the basis of equal wing area, as shown in the partial plan view comparing the outlines of the two airplanes. When calculating the performance of the Model WA-22, it was therefore assumed that the lift and profile drag coefficients of the two models were essentially the same. The outer portions of the wings of the Model WA-22 had great taper and aspect ratios than the Model WA-14, and these differences were factored in when calculating the profile drag coefficient of the airplane, which was estimated to be .0242, an excellent figure for a flying boat of this era. Roughness of the Model WA-22’s surface due to rivet heads and lapped joints as well as minor external parts omitted from the wind tunnel model but installed on the actual airplane likely would have appreciably increased the drag, however. The amphibian gear was assumed to be fully retractable.

The Model WA-22’s maximum speed was 266 mph at 20,000 ft. It had a wing loading of 20 lbs./sq. ft., giving it a higher landing speed than that calculated for the WA-14, which only had a wing loading of 17.9 lbs./sq. ft. With flaps off, the airplane’s landing speed was 72 mph; with flaps on, it was reduced to 64 mph. It was possible for the wing loading on the WA-22 to be increased to 30 lbs./sq. ft, giving it a gross weight of 26,400 lbs. with a considerable increase in useful load. In this event, a more effective flap arrangement would have been necessary to maintain the landing speed at 64 mph.

The static longitudinal stability of the Model WA-14 obtained from the wind tunnel test results was found to be entirely satisfactory. Lee-Wendt Aircraft determined that the WA-22 had an even higher degree of stability, which was probably considerably more than required under the most severe specifications. This was primarily due to the fact that the tail area was a much larger percentage of the wing area on the Model WA-22, while the ratio of tail arm to mean aerodynamic chord was also greatly increased. Both the tail area and arm could have been decreased considerably and still have given satisfactory longitudinal stability; such changes would have probably reduced the drag somewhat, improving performance.

The aforementioned estimates of stability were obtained by neglecting the effect of the vertical position of the center of gravity. Any changes in the design that lowered this point would have resulted in a somewhat greater degree of stability in flight, with stability in roll on the water also being improved. The most obvious way of making such an improvement would have been to employ inverted engines partially enclosed in the wing, which would have also resulted in lower drag and better performance.

Another wind tunnel test of the Model WA-14 model was conducted at the MIT Daniel Guggenheim Aeronautical Laboratory in March of 1938 at the request of Stout Engineering Laboratories. The object of the test was to obtain data on the lift and drag of the amphibian. Overall, the MIT test produced slightly more pessimistic results than the University of Michigan, though it generally confirmed the data produced in the earlier wind tunnel work. MIT researchers modified the method by which the speed of the full-scale aircraft was determined, attempting to estimate the NACA net efficiency of the nacelle propeller combination rather than estimate separately the increased drag for the nacelles and the propulsive efficiency. MIT also noted that any modification such as widening of the fuselage near the tail or increasing the sharpness of the chine (presumably to improve stability on the water) would result in an increase in drag. Finally, exploration with yarn tufts showed that the wing stalled first about halfway out, then spread inward, with finally the tip stalling.

The Amphibion was, of course, never built. The author has been unable to uncover any Navy correspondence regarding the project or why it was ultimately rejected. In terms of configuration, the aircraft certainly appeared more advanced than the standard US flying boats of the day, such as the Consolidated PBY Catalina. Any number of factors could have killed it: Navy skepticism regarding the designers’ claims; the inexperience and small size of the companies involved; the fact that the aircraft was not designed to a particular Navy specification; lack of government funds; or the difficulty of mass producing a plane with such complex wing-fuselage blending with late 1930’s production techniques. Lee-Wendt and Stout didn’t help their cause by submitting what was essentially a commercial design without provision for armament, judging by the surviving drawings. In any case, please click through the gallery above to view these handsome designs in greater detail.

All images from NARA Archives I, Washington DC, RG 36

Sources:

“Performance and Longitudinal Stability of the Lee-Wendt Amphibion Model, WA-22,” Lee-Wendt Aircraft and Stout Engineering Laboratories, 1937-38, NARA Archives I, Washington DC, RG 36

M.I.T. W.T. Report No. 398, “Report on Wind Tunnel Test of Flying Boat Model,” March 9, 1938, NARA Archives I, Washington DC, RG 36

 Leave a Reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

(required)

(required)