• Version
• 49 Downloads
• 163.18 KB File Size
• 1 File Count
• November 4, 2016 Create Date
• November 4, 2016 Last Updated

National Advisory Committee for Aeronautics, Technical Notes - A Dangerous Seaplane Landing Condition

A peculiar phenomena in seaplane landing is observed and
reported. The seaplane having executed a normal fast landing at
low incidence a forward movement of the control stick effected
an unusual condition in that the seaplane left the water sudden—
ly in‘an abndrmal attitude. The observations describing this
phenomena are offered as a warning against possible accident
and as a conjectural cause of seaplane landing accidents of a
certain kind.

During the investigation of the pressure distribution on
the bottom of the pontoon of a seaplane, the Vought UO_l With
Wright "Whirlwind" engine which comprised an exhaustive routine
of landing, take—off, taxying, etc., conditions, a very peculiar
phenomena was observed.with abnormal consequences. It was evolved
in the following manner. On fairly smooth water and directly into
a moderate wind, the seaplane was landed at low incidence, fairly
fast, with part power on. Some discussion among the personnel
handling the tests as to the condition which Would produce the
maximum positive pressures on the forward part of the pontoon
indicated.that this might be attained by pushing forWard on the_
stick during this condition of landing. Consequently; during
the landing of this character under the conditions above stated
the cOntrol stick was pushed rather suddenly forward a distance-
of about 6 inches. With considerable abruptness the seaplane
appeared to rock forward onto the “toe" of the pontoon and then
leave the water,."bouncing" to a height estimated by observers
from the beach of about 10 feet. During this "bounce" there
was no tendency for the nose to rise as in the more usual "por—
poising" condition,_the feeling being that the airplane was
travelling at a small negative angle of attack. it the top of
the “bounce" there was a tendency to nose over, which was coun-
teracted with some difficulty by the elevators; and a rather
poor pancake landing_with the tail only moderately well down
was then made, the engine failing to pick up when throttle wasg
applied.

A number of attempts were made to duplicate the.conditions
as in the first effort, with consequences generally similar but
of varying intensity and slightly modified.behavior. It is evi—
dent that such procedure applied by a pilot of small experience_
on seaplanes might produce unpleasant results, and it is sug-
gested that landing accidents can be recalled where these con—
ditions may’have obtained which have resulted in the seaplane
nosing in after the initial “bounce" with considerable injury
to the airplane and its occupants.