Joint U.S.-Canadian Aviation Projects and UFO Sighting Reports, 1954-1955

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such an undertaking must depend on (a) the significance of the ob-
jectives which the new airplane claims to fill and (b) the sound-
ess of the means proposed to attain these objectives.

The key feature on which the design of the Y2 is based is the
utilization for hovering of the pressure built up in the center of
an annular jet stream. This pressure build-up increases the lift
at standstill close to the ground in such a fashion as to indicate
the practicability of hovering a few feet off the ground with en-
gines whose static sea level thrust, without this augmentation from
ground effect, would be less than the airplane gross weight. Also,
because of the nature of the ground effect, the aircraft would be
stable with respect to height when hovering; that is, it would not
require pilot attention to hold a height above the ground, although
it would require control to maintain its attitude. The thrust aug-
mentation for hovering obtained by A. V. Ros in small scale tests is
of the order of 60 to 80%. Because the appropriate variables were
not investigated and the pertinent measurements not made during the
tests, data are not available to extrapolate this result properly to
predict accurately full scale augmentation factors. There are many
features which could make the full scale augmentation factors smaller
but very little likelihood of their being larger than in the model.
The possibility of stable hovering is, nevertheless, an engaging
feature. Unfortunately, it has dominated the evolution of the con-

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