User manual

Part B SectionAppendix A.2
The aircraft literally ricochets back into the air like a stone skipped across a pond. With
power off such skipping usually stops after 2-4 bounces but slight nose down attitude
adjustment (back to the optimum landing attitude) will stop the skipping promptly.
17 SURFACE CONTACT WITH DRIFT
Landplane pilots are used to judging drift by reference to a fixed surface, usually the
runway. When landing on water an approach that seems to have no drift will still have drift
equal to the movement of the wavelets. Although the Catalina is robust, compensation for
drift must be added in as much as possible and extra compensation added to allow for
water movements.
18 SURFACE CONTACT OUT OF BALANCE
Contact with the ball out of centre results in a rapid realignment of the longitudinal axis of
the aircraft. This will produce a rolling moment that can be sufficient to dig in one wingtip
float. This can be disastrous if the nose attitude is at all low and will usually result in failure
of the nose gear doors and a water loop. The ball usually goes out to the right as power is
reduced and this will be an additive to a destabilizing crosswind from the left. Power on
approaches are safer in this regard.
19 TOWING THE AIRCRAFT
It is not anticipated that towing will be necessary but if due to engine failure or the like
towing is the only safe way to handle the aircraft the following should be considered.
Tow line force, hydrodynamic forces, aerodynamic forces and buoyancy all influence the
behaviour of the aircraft under tow.
Upwind
Towing is more or less stable. Yaw induced by wind and/or waves will tend to be
countered by the tow force and return the aircraft to the tow path direction.
Crosswind Towing can be stable but the aircraft longitudinal axis will not be parallel to the
tow direction. Towing in waves sees the tow line force vary periodically and when the line
is slack the aircraft will yaw more into wind. This yaw increases the tow line force and
stabilizes the situation.
Downwind
towing can be stable only if the tow line force overcomes the aerodynamic forces trying to
weather-cock the aircraft into wind. This requires higher tow speeds and becomes
impractical in all but the most gentle breeze. Towing the aircraft by the tail can make things
more manageable but the best solution is the use of a sea anchor or drogue to increase
the hydrodynamic force to balance the aerodynamic forces.
Stichting Catalina PH-PBY Rev No: 02
01 April, 2006 Page: 5