Landing
in very gusty wind
conditions
by Paul Dewurst (2003 Word Champion)
If you sit in your machine on the ground at the end of the runway,
peer ahead and see where the horizon cuts through your windscreen
and make a mental note, or even make a chinagraph mark.
This will obviously be the flat '3 point' attitude.
In flight
attitude is dependant upon airspeed and it is easy to fly along
with the nose down lower than this at high speed. You must touchdown
on the runway with the nose higher than this or the nosewheel will
touch first.
If this happens to the hapless pilot then the nosewheel being forward
of the Cg,
causes the nose to be rotated up throwing you back in the air.
The sequence can then be for our forementioned hapless pilot to
throw the stick forwards in panic,
slam the nosewheel back into the ground and repeat the whole process
again with increasing force,
eventually the aircraft stops doing this when speed falls or as
witnessed neatly
recently at Sywell with a Cessna 152 right outside our office
the noseleg gives up in disgust and snaps off with the obvious expensive
consequences.
So the
key thing for landing is to touch down in the right attitude i.e
at least a little bit nose higher than the chinagraph mark. In normal
conditions this is instinctive for most, fully held off slow speed
touchdowns being the aim.
However
in gusty conditions or strong crosswinds the fully held off landing
is not so desirable because as the speed reduces so does the control
effectiveness.
So the normal advice is to 'fly the aircraft on' to the ground,
so as
to keep good control against the crosswind or turbulence until firmly
on the ground.
Putting the flaps down effectively changes the incidence of the
wings relative to the fuselage,
and result in a more nose down attitude for a given speed when compared
to no flap.
So when 'flying the aircraft on to the ground' in these conditions
and with full flap it is possible with a high enough airspeed to
touch down with the nose too low and 'wheelbarrow'. So the advice
is for such
an approach that selecting no or only first stage of flap may be
more suitable
in these conditions and when the extra few knots of stall speed
are not a problem.
regular practice of landing both powered and glide approaches and
all flap configurations
and watching that chinagraph mark will soon build a confident
handling ability for all configurations / conditions.
Powered
approaches are usually the most reliable for short landing.
This is because the approach path can constantly be adjusted with
power
and pitch changes whilst maintaining the optimum airspeed. Power
also reduces
stall speed slightly, meaning slightly slower approach speeds can
be used
with the same margin of safety. Also the rotation for round out
and the amount
of vertical inertia is less again meaning slower speeds can be used.
However
for best affect razor sharp speed control is required and the power
must not be reduced too early for round out!
Glide
approaches may be better when a short landing over an obstacle on
approach is called for.
In this case speed can be regulated / approach path controlled
(different sides of the same coin) by use of sideslip. be aware
however
that a fully sideslipped approach power off will result in a high
rate
of descent and accompanying vertical inertia which will require
adequate
airspeed and positive round out to arrest. Wind gradient will also
add significantly to this. Best to add a few knots for wife and
kids,
and learn the knack of shedding speed by side slipping in the hold
off.
'Airspeed
is cash in hand and altitude is money in the bank. Have neither
and you are broke'!!
Paul
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