The model after covering, with motors “tilted for take-off or landing”. A small crank handle for adjusting the nacelle tilt angle may just be seen on the wing centre section.

Otwell had a model built as a proof-of-concept machine, based on his 1934 patent. Of trimotor configuration, the model is seen in these photographs before the wings have been covered, the picture above apparently having been taken before the engine mountings or engines have been fitted. The image at left shows the model with the engines fitted and positioned horizontally for forward flight, with the picture below depicting the wing-mounted 0-6 b.h.p. Forster .99 spark-ignition motors in their vertical position for landing. The patent stated that any position between horizontal and vertical could be selected.

Another illustration of dubious quality apparently depicting a pair of trimotors fitted with Otwell’s tiltable engine arrangement. The machine furthest away is flying with the motors in the horizontal mode for forward flight, while the nearest appears to be preparing to alight on a somewhat jagged bed of very unfriendly-looking rocks!

Otwell promoted his concept with some illustrations of indifferent quality, this example showing a trimotor aircraft with the radial piston engines tilted in the vertical position and an inset of gulls alighting on water to demonstrate the effect.

Illustrations from Otwell’s patent granted in October 1932. Fig 1 shows a front view of the engine mountings attached to the wing; Fig 2 is a side elevation of one of the engines in its mounting in the horizontal position, with dashed lines showing the vertical position; Fig 3 is a plan view showing the sprung, sliding bolt that locates in notches in the guide rail; Fig 4 shows the nacelle angle-fixing mechanism.

An illustration from Otwell’s improved and simplified patent dated July 10, 1934. Fig 5 shows the flexible fuel pipe with springs marked as “36”.