Stearman Wheel Landings
by Tom Lowe
Just mention the words, “wheel landings”, among any group of
tailwheel pilots and you are certain to evoke a reaction that will
lead to a lively discussion of the pros and cons of this maneuver
that most likely will degenerate into an argument in which no one
is willing to budge on his or her chosen position. The opinions
will vary from those who highly favor the use of wheel landings to
those who have no use for them whatever and feel that a full stall
three point landing should be used under all conditions. There
seems to be no middle ground on the subject of wheel landings
and very seldom is anyone likely to succumb to the arguments of
the other side and change their viewpoint.
Published opinions on wheel landings run the gamut from William
K. Kershner who states in his book, The Advanced Pilot’s Flight
Manual, “The wheel landing is the best means of landing the
tailwheel airplane in strong and/or gusty wind conditions in that
the plane contacts the ground at a low angle of attack”; to the
popular novelist, Stephen Coonts, who as a neophyte tailwheel
and Stearman pilot boldly states in his book, The Cannibal
Queen, “This method of touching down on the main wheels and
holding the tail off as the aircraft slows is fun to practice, but it is
not the recommended method for getting a taildragger safely down
on strange airports in gusty winds.” He also remark
pilots converted to taildraggers are convinced that they don’t need
to learn or practice wheel landings because three-point landings
are ‘just as good’. The pilot who believes this is seriously short
changing himself, and won’t realize his error until he finds himself
attempting a landing in 15-18 knot gusting crosswinds. The
reason that wheel landing training is mandatory is that it allows
the pilot to place the landing gear on the ground with a lower
angle of attack and higher speed, hence with a greater degree of
control. It is of course natural for a beginning taildragger pilot to
not understand this need. However, if your instructor shares this
line of thinking, consider yourself lucky to have made the
discovery, and keep on looking. Until the taildragger pilot can
perform acceptable wheel landings, he should consider himself at
the student level (regardless of how many hours grace his
logbook), and stay close to his instructor where his solo flying can
be supervised.”
He goes on to say, “If your taildragger checkout ended this way, it
is unfortunate since you were shortchanged and have been left
high and dry with an incomplete checkout. The price you will pay
(or have paid) for this is a serious limitation in your use of the
taildragger. There will be days when wind conditions will render
the wheel landing mandatory simply because the stall landing will
result in a bent airplane. These wind conditions are high and
gusty winds as well as gusty crosswinds. In summary, anything
less than a complete taildragger checkout is a farce placing you in
the position of an accident waiting for a place to happen. And a
complete checkout includes proficiency in wheel landings.”
While these last two quotes were aimed primarily at pilots just
beginning their transition into tailwheel airplanes, they certainly
apply to all tailwheel pilots, regardless of their experience level,
and to Stearman pilots in particular.
Those of you who attend fly-ins and air shows most likely have
observed that almost every professional air show pilot who flies a
450 h.p. Stearman wheel lands his airplane. Also, most pilots of
high performance tailwheel airplanes such as AT-6s, P-51s, D-18
Twin Beechs and DC-3s, etc. also prefer to make wheel landings.
There is a reason for this, which I hope will become apparent as
you read this article. To quote again from The Compleat
Taildragger Pilot: “In fact, if you had been around a generation
ago to watch the local pros shooting wheelies in the old twin
Beech 18’s or DC-3’s, it would have appeared to be the easiest
maneuver in the world. The pros use this type of landing so much
because, once learned, it is so easy to perform.”
Before launching into a further technical discussion of wheel
landings I must state that I am a strong advocate of the use of
wheel landings and believe that every tailwheel pilot should be
proficient in this maneuver. Personally, I also prefer to make
wheel landings whenever landing a Stearman on hard surfaced
runways. Regardless of your feelings as to whether or not wheel
landings are the thing to do, it is a maneuver and technique that
every Stearman pilot should master and remain proficient in
performing.
PROCEDURE
Fly a normal traffic pattern and carry an additional 5 mph or 5 kts
(depending on your airspeed indicator) on the final approach. The
landing transition is made at a lower height than for a full stall
landing because the airplane must touch down at a higher
airspeed and the attitude will be only slightly tail low – not three
point. As you begin to flare add in a small amount of power and
carry it until the wheels make contact with the ground. The
primary purpose of adding power throughout the landing, besides
maintaining the additional airspeed, is to permit the wheels to
contact the ground with a minimum downward velocity (rate of
descent). You literally fly the airplane onto the ground and are
“feeling” for the runway. Remember – a wheel landing is not an
accuracy landing. With the extra airspeed and power, you will use
up more of the runway than you would with a three point landing.
When the main gear contacts the ground you must simultaneously
ease forward on the stick (down elevator) to keep the airplane on
the ground (maintaining the low angle of attack of the wing) and
reduce the throttle to idle. The amount of forward stick pressure
required at the point of touchdown will be small if the downward
momentum (rate of descent) of the airplane was low. Remember,
the primary reason forward stick is applied at the moment of
impact is to counteract the downward momentum of the C.G. of the
airplane. Continue to increase the application of forward control
stick movement as the airplane slows down to keep the tail up
until it descends of its own accord with the stick full forward. Once
the tail has lowered to the ground, apply full up elevator to keep
the tail on the ground as you would do in a three point full stall
landing. If you are landing with a crosswind, normal crosswind
aileron and rudder control correction inputs should also be
applied.
Use only the minimum amount of power during the
landing as is required to maintain the airspeed and to arrest the
rate of descent. Excessive power can lead to unnecessarily high
airspeed and subsequently, a much longer runway requirement.
But as the pilot sees the runway disappearing behind him, he
likely may become impatient and force the airplane onto the
runway with forward stick pressure. A bounce usually will result
which can then develop into a series of porpoises down the
runway. Should this occur, add power, go around and try it again.
A go-around after a botched wheel landing usually is preferable to
trying to save it as you bounce down the runway.
There are also two additional aerodynamic factors which come
into play during a wheel landing, particularly while the tail is
descending from its initial high position down to the ground.
These are torque, or propeller P factor, and the center of gravity of
the airplane. Torque and P factor usually are discussed relative to
making a take-off, but they also apply during a landing, however to
a lesser degree since the engine power is being reduced rather
than increased.
Torque is the term that is commonly used to describe the left
turning tendency of most American built airplanes in which the
propeller rotates counter-clockwise as viewed from the front of the
airplane. What really is happening is more accurately described
by an understanding of the phenomenon known as P factor. P
factor is developed by the fact that the downward moving propeller
blade (the one on the right side of the airplane as viewed from the
cockpit) has a higher angle of attack than that of the upward
moving blade on the left side of the airplane. Additionally, the
downward moving blade also has a slightly higher relative velocity
with respect to the air. The aerodynamic result is that the
descending right blade produces more lift, or in this case – thrust –
than the ascending left blade. The ultimate consequence of this is
that the airplane wants to turn to the left.
The other factor that has an effect on the airplane during the
landing is the location of its center of gravity. Tailwheel airplanes
in which the C.G. is relatively close to the main landing gear tend
to be more stable with respect to their ground looping tendency.
The Stearman’s C.G. location falls into this category, but I’m not
really sure if its location has much effect on negating the
Stearman’s propensity to ground loop. The Stearman is also
affected by the often forgotten consideration with respect to the
height of the C.G. location above the wheels. In the case of the
Stearman, the biplane configuration concentrates the weight of the
fuel in the center section, high above the wheels on the ground.
This additional moment to the height of the C.G. adds to the
reduced stability of the Stearman on the ground and is a
contributing factor to its well-known tendency to ground loop.
Both of these factors have an effect on the directional control of the
Stearman during a wheel landing, especially as the tail is
transitioning down to the ground. The P factor is present, although
in a much reduced amount since the power is at idle, and the
airplane will still have a tendency to want to turn to the left. The
high center of gravity is always present and there is not much that
can be done about that, it just is a constant factor contributing to
the characteristics of the airplane. All of this is coming into play as
the tail descends to the ground, exactly when the rudder is
beginning to lose its effectiveness. This probably is the most
critical time for the pilot during a wheel landing – maintaining the
directional control of the Stearman while in this transitional phase.
(But then again – maintaining directional control in ANY landing in
a Stearman is the primary problem.)
The above mentioned problem during the time period when the
tail is transitioning from its landing attitude down to the ground is
most likely the main concern of those pilots who oppose the use of
wheel landings and favor full stall three point landings at all times.
They will say, “The tail has to come down sometime, so you might
as well make a three point landing in the first place.” There is a
certain degree of validity to this argument. However, a good
competent, proficient tailwheel pilot can maintain control of the
airplane throughout the wheel landing with no problem and take
full advantage of the benefits it offers.
Stearmans have a fairly high wing loading and another technique
to take advantage of this particular characteristic during the
transition phase is to maintain the forward stick pressure that was
applied at touchdown. Don’t push forward further. This allows the
tail to lower a bit more quickly as the airspeed decreases. The
tailwheel will contact the runway before the rudder loses its
effectiveness, but still at a speed which will allow the application
of full up elevator without the danger of the airplane becoming
airborne again.
Another factor that can have an impact on the performance of a
wheel landing is the sitting position of the pilot in the cockpit. This
is equally as important in three point landings and take-offs as
well. It is important that the pilot’s body, and his head in particular,
be aligned with the centerline of the fuselage along the
longitudinal axis of the airplane. The common tendency of most
pilots is to lean to one side of the cockpit or the other, in order to
look around the side of the windshield and alongside the fuselage
in order to gain better visibility. Usually, pilots lean to the left side
as this is most natural since the left hand is on the throttle
quadrant on the left side of the fuselage and the right hand is on
the stick. The consequence of this leaning is that the control stick
is drawn to that side of the airplane, introducing up aileron on that
side, resulting with a wing that is forced down whether that’s
where you want it or not. So it is imperative that the pilot should
remain aligned with the centerline of the airplane to avoid this
unneeded control input. You should sit straight and your eyes
should look past the side of the windshield, between the wings,
along the side of the fuselage at an angle so as to focus on the
edge of the runway several hundred feet in front of the airplane. In
this manner you can judge your height above the ground, as well
as the drift and alignment of the airplane with the runway.
The height that a pilot sits in the seat also plays an
important role in the landing. In the WW II U.S. Navy training films
the Navy recommended that the seat height be adjusted so that
the pilot’s eyes are looking directly through the center of the
windshield. Personally, I find this just a bit too low for me, I prefer
to sit higher than that. Usually I sit as high as my seat will allow to
permit maximum visibility around the nose. Whatever seat height
position you are comfortable with and are accustomed to using in
your Stearman is what you should continue to employ while
making wheel landings. Don’t change it. That way your site
picture will remain constant regardless of whether you make a
wheel landing or a three point landing.
Your feet position on the rudder pedals also is important. Your
heels should rest on the floorboards with the balls of your feet on
the lower portion of the rudder pedals. Don’t have them raised up
high so as to get onto the brake portion of the pedals. While this
seems to be very basic and unnecessary to comment upon – rest
assured – the absolute last thing you want during a wheel landing
is to have the brakes being applied when you touch down.
As noted several times before, one of the prime uses for wheel
landings is in strong crosswinds. When landing in a crosswind it
is imperative that at touchdown all drift has been eliminated and
that the airplane is tracking STRAIGHT DOWN THE RUNWAY.
To accomplish this, apply the normal crosswind control
corrections; wing down into the crosswind with aileron to stop the
drift and enough opposite rudder to insure that the airplane is
going straight. This will result in touching down on the upwind
wheel first, followed thereafter with the other wheel. As the
airplane slows down continue to increase the aileron and rudder
input as necessary to keep the wings level and the airplane going
straight. Once the tailwheel is on the ground the steering will
become more positive, but be sure to maintain the crosswind
corrections and full up elevator to keep the tail firmly grounded.
Another method of making wheel landings that some pilots favor is
what I call the power-off, tail low landing. In this scenario the pilot
flies a normal approach, power-off and begins to flare as you
normally would for a full stall three point landing. When the tail
attitude is low, but not yet in contact with the ground, the pilot adds
engine power, or sometimes keeps the power at idle, and then
introduces forward control stick (down elevator) in an attempt to
“roll” it onto the runway.
This method completely nullifies the purpose and advantages of a
wheel landing which is to fly the airplane onto the ground at a
higher airspeed with a minimum angle of attack on the wing. In
this tail low method you place yourself into a sort of “never-never
land” upon touchdown and introduce into the equation all the
factors that are detrimental to maintaining directional control of the
airplane. The airplane is slow, the wing is at a higher angle of
attack, the rudder is beginning to lose its effectiveness, and power
possibly is being introduced which increases the P-factor and
adds to the left turning tendency. Throw in some crosswind and a
possible bounce on the touchdown and you are setting yourself up
for a trip off the side of the runway into the weeds – or worse. If
you choose to perform this type of wheel landing – you might as
well go ahead and make a full stall three point landing. You’ll be
a lot better off!
I have been very fortunate throughout my Stearman flying days in
that my home airport has three long grass runways and I have
spent most of my time enjoying the pleasures that grass provides.
As you know too well, the Stearman is a unique tailwheel airplane
and has some ground handling characteristics uncommon to
many other tailwheel airplanes. It really likes to ground loop and
you must remain ever vigilant upon every landing, whether it’s a
three point or wheel landing. The Stearman is no respecter of
persons or their experience level and is ever ready to humble the
unwary pilot. What exactly it is that makes it so is really hard to
pinpoint. The Stearman has a relatively narrow main landing
gear, a high center of gravity, large side fuselage and tail surface
areas and wheels with toe-in (cambered inwards). All of these
contribute to its willingness to jump up and bite you in the buttocks
(as Forrest Gump would say) at every opportunity.
Now take the Stearman to a paved runway and it will release the
“beast” that is hidden within. The Stearman definitely is a different
airplane on pavement than what it is on grass. Grass is the great
equalizer! For whatever reason, the tires just seem to reach out
and grab the pavement and bite into the ground. We have all
either observed, or most likely ridden through, landings on
pavement where the screech of tires is heard above the rumble of
the engine and the Stearman careens from one side of the runway
to the other until it is finally brought under control by its breathless
pilot. It doesn’t seem to get much better as your experience level
grows either. I have approximately 3000 hours of flying time in
Stearmans and still to this day, every landing on a hard surfaced
runway is preceded by a feeling of apprehension, a dry mouth, a
tightening of the sphincter muscle which induces an advanced
case of “pucker” that leaves me wondering if this will be the
Stearman landing that will finally jump up and grab me. I
constantly practice landings, both three point and wheel, on the
paved runways at airports near my home field to maintain my
proficiency. What all this rambling is leading up to is that I
personally prefer to make wheel landings in Stearmans on paved
runways. I feel that I have a greater degree of control over the
vagaries of the Stearman with a wheel landing as opposed to the
three point landing. Regardless of all the dire comments I have
just uttered, the Stearman is a wonderful airplane with a mystique
all its own and there is absolutely nothing more satisfying than
making a squeaker landing in a Stearman.
ADVANTAGES OF THE WHEEL
LANDING
Maximum controllability of the airplane through the touchdown
point.
§ Reduced susceptibility to being adversely affected by wind
gusts.
§ Improved visibility during the landing and rollout.
§ Ability to set the airplane on the ground at any airspeed (within
reason) above stall speed.
§ Ease of transition from one tailwheel type to another.
§ Safety in face of unknown factors such as:
Night landings (when visual acuity and depth perception are
reduced)
Overloaded airplane
Airplane with C.G. out of limits ( particularly an aft C.G.)
Airplane iced up such that exact stall speed is uncertain
DISADVANTAGES OF WHEEL
LANDINGS
§ More difficult to learn, master and maintain proficiency.
§ Uses a greater amount of runway during landing and rollout.
§ Potential for a bounced landing developing into a series of
bounces which may lead to a loss of directional control.
§ Potential for loss of directional control during the transition
phase while the tail is coming down to the ground.
§ Too much airspeed on approach – the airplane floats during the
landing.
§ Excessive amount of power during the landing.
§ Failure to apply forward stick pressure and reduce power
simultaneously at the time the main wheels touch the ground.
§ Excessive downward velocity (rate of descent) at touchdown.
(not enough power)
§ Getting impatient – diving at the runway or trying to force the
airplane onto the ground.
§ Too slow approach airspeed or leveling off in the flare too high –
the airplane settles fast onto the main gear and bounces.
§ Trying to salvage the landing after a bounce. (add the power
and go around and try it again)
COMMON ERRORS IN MAKING
WHEEL LANDINGS
There is one more final point to make. Wheel landings and soft
field conditions do not mix. If you are going into a soft field, make
a three point landing.
In summation, I would like to emphasize that the opinions and
preferences presented in this article are entirely those of the
author and in no way reflect any official position of the SRA. What
I have described reflects the way in which I was taught to fly
tailwheel airplanes and my observations gathered over 36 years
of flying and instructing in tailwheel airplanes. This is how I fly my
Stearman and how I teach my students.
I again would like to quote from The Compleat Taildragger Pilot
where its author, Harvey S. Plourde states, “No maneuver in basic
VFR flying is as poorly understood as the wheel landing. Yet, the
wheel landing is vital to the taildragger pilot’s safety. Without the
knowledge, experience, or skill to perform this maneuver, the pilot
severely limits the use of his taildragger to relatively benign wind
conditions. He also endangers the lives of his passengers, if, in
such ignorance, he ventures forth in conditions which give him 90
degree crosswinds in the 12 gusting to 18 knot range.”
Whether or not you agree or disagree with me concerning the
material and opinions I have presented in this article on wheel
landings, I believe that every Stearman pilot should know how to
do a wheel landing and should maintain proficiency in its
execution. To do so is to add another weapon into your arsenal of
skills to be called upon for use whenever needed. Whether you
choose to use the wheel landing, and under what conditions,
always will remain the option of the pilot. If you have never
mastered this skill or have let your wheel landing proficiency
become encrusted with rust, I would urge you to locate a good
tailwheel Flight Instructor in your area (preferably one with
Stearman experience) and get a few hours of dual instruction.
You’ll be a better pilot for it.
Tom Lowe is a Boeing 747-400 Captain for United Airlines based at
O’Hare Field, Chicago, Illinois. He served as the President of the SRA
for over 20 years and has owned and flown Stearman airplanes for over
30 years. He is a “Gold Seal” Certified Flight Instructor rated for
Airplanes, Single and Multi-engine Land; Instrument and Glider. He also
holds both the Advanced and Instrument Ground Instructor ratings. In
his spare time he specializes in Stearman, AT-6 and T-34 checkouts as
well as general tailwheel flight instruction.
Editors Note:
Supporting or alternate views on Wheel Landings vs ThreePoint
Landings are welcome for future publications of the Stearman flying
Wire.
http://www.cafutahwing.org/uploads/1/0/8/2/10827645/stearman_wheel_landings.pdf
by Tom Lowe
Just mention the words, “wheel landings”, among any group of
tailwheel pilots and you are certain to evoke a reaction that will
lead to a lively discussion of the pros and cons of this maneuver
that most likely will degenerate into an argument in which no one
is willing to budge on his or her chosen position. The opinions
will vary from those who highly favor the use of wheel landings to
those who have no use for them whatever and feel that a full stall
three point landing should be used under all conditions. There
seems to be no middle ground on the subject of wheel landings
and very seldom is anyone likely to succumb to the arguments of
the other side and change their viewpoint.
Published opinions on wheel landings run the gamut from William
K. Kershner who states in his book, The Advanced Pilot’s Flight
Manual, “The wheel landing is the best means of landing the
tailwheel airplane in strong and/or gusty wind conditions in that
the plane contacts the ground at a low angle of attack”; to the
popular novelist, Stephen Coonts, who as a neophyte tailwheel
and Stearman pilot boldly states in his book, The Cannibal
Queen, “This method of touching down on the main wheels and
holding the tail off as the aircraft slows is fun to practice, but it is
not the recommended method for getting a taildragger safely down
on strange airports in gusty winds.” He also remark
pilots converted to taildraggers are convinced that they don’t need
to learn or practice wheel landings because three-point landings
are ‘just as good’. The pilot who believes this is seriously short
changing himself, and won’t realize his error until he finds himself
attempting a landing in 15-18 knot gusting crosswinds. The
reason that wheel landing training is mandatory is that it allows
the pilot to place the landing gear on the ground with a lower
angle of attack and higher speed, hence with a greater degree of
control. It is of course natural for a beginning taildragger pilot to
not understand this need. However, if your instructor shares this
line of thinking, consider yourself lucky to have made the
discovery, and keep on looking. Until the taildragger pilot can
perform acceptable wheel landings, he should consider himself at
the student level (regardless of how many hours grace his
logbook), and stay close to his instructor where his solo flying can
be supervised.”
He goes on to say, “If your taildragger checkout ended this way, it
is unfortunate since you were shortchanged and have been left
high and dry with an incomplete checkout. The price you will pay
(or have paid) for this is a serious limitation in your use of the
taildragger. There will be days when wind conditions will render
the wheel landing mandatory simply because the stall landing will
result in a bent airplane. These wind conditions are high and
gusty winds as well as gusty crosswinds. In summary, anything
less than a complete taildragger checkout is a farce placing you in
the position of an accident waiting for a place to happen. And a
complete checkout includes proficiency in wheel landings.”
While these last two quotes were aimed primarily at pilots just
beginning their transition into tailwheel airplanes, they certainly
apply to all tailwheel pilots, regardless of their experience level,
and to Stearman pilots in particular.
Those of you who attend fly-ins and air shows most likely have
observed that almost every professional air show pilot who flies a
450 h.p. Stearman wheel lands his airplane. Also, most pilots of
high performance tailwheel airplanes such as AT-6s, P-51s, D-18
Twin Beechs and DC-3s, etc. also prefer to make wheel landings.
There is a reason for this, which I hope will become apparent as
you read this article. To quote again from The Compleat
Taildragger Pilot: “In fact, if you had been around a generation
ago to watch the local pros shooting wheelies in the old twin
Beech 18’s or DC-3’s, it would have appeared to be the easiest
maneuver in the world. The pros use this type of landing so much
because, once learned, it is so easy to perform.”
Before launching into a further technical discussion of wheel
landings I must state that I am a strong advocate of the use of
wheel landings and believe that every tailwheel pilot should be
proficient in this maneuver. Personally, I also prefer to make
wheel landings whenever landing a Stearman on hard surfaced
runways. Regardless of your feelings as to whether or not wheel
landings are the thing to do, it is a maneuver and technique that
every Stearman pilot should master and remain proficient in
performing.
PROCEDURE
Fly a normal traffic pattern and carry an additional 5 mph or 5 kts
(depending on your airspeed indicator) on the final approach. The
landing transition is made at a lower height than for a full stall
landing because the airplane must touch down at a higher
airspeed and the attitude will be only slightly tail low – not three
point. As you begin to flare add in a small amount of power and
carry it until the wheels make contact with the ground. The
primary purpose of adding power throughout the landing, besides
maintaining the additional airspeed, is to permit the wheels to
contact the ground with a minimum downward velocity (rate of
descent). You literally fly the airplane onto the ground and are
“feeling” for the runway. Remember – a wheel landing is not an
accuracy landing. With the extra airspeed and power, you will use
up more of the runway than you would with a three point landing.
When the main gear contacts the ground you must simultaneously
ease forward on the stick (down elevator) to keep the airplane on
the ground (maintaining the low angle of attack of the wing) and
reduce the throttle to idle. The amount of forward stick pressure
required at the point of touchdown will be small if the downward
momentum (rate of descent) of the airplane was low. Remember,
the primary reason forward stick is applied at the moment of
impact is to counteract the downward momentum of the C.G. of the
airplane. Continue to increase the application of forward control
stick movement as the airplane slows down to keep the tail up
until it descends of its own accord with the stick full forward. Once
the tail has lowered to the ground, apply full up elevator to keep
the tail on the ground as you would do in a three point full stall
landing. If you are landing with a crosswind, normal crosswind
aileron and rudder control correction inputs should also be
applied.
Use only the minimum amount of power during the
landing as is required to maintain the airspeed and to arrest the
rate of descent. Excessive power can lead to unnecessarily high
airspeed and subsequently, a much longer runway requirement.
But as the pilot sees the runway disappearing behind him, he
likely may become impatient and force the airplane onto the
runway with forward stick pressure. A bounce usually will result
which can then develop into a series of porpoises down the
runway. Should this occur, add power, go around and try it again.
A go-around after a botched wheel landing usually is preferable to
trying to save it as you bounce down the runway.
There are also two additional aerodynamic factors which come
into play during a wheel landing, particularly while the tail is
descending from its initial high position down to the ground.
These are torque, or propeller P factor, and the center of gravity of
the airplane. Torque and P factor usually are discussed relative to
making a take-off, but they also apply during a landing, however to
a lesser degree since the engine power is being reduced rather
than increased.
Torque is the term that is commonly used to describe the left
turning tendency of most American built airplanes in which the
propeller rotates counter-clockwise as viewed from the front of the
airplane. What really is happening is more accurately described
by an understanding of the phenomenon known as P factor. P
factor is developed by the fact that the downward moving propeller
blade (the one on the right side of the airplane as viewed from the
cockpit) has a higher angle of attack than that of the upward
moving blade on the left side of the airplane. Additionally, the
downward moving blade also has a slightly higher relative velocity
with respect to the air. The aerodynamic result is that the
descending right blade produces more lift, or in this case – thrust –
than the ascending left blade. The ultimate consequence of this is
that the airplane wants to turn to the left.
The other factor that has an effect on the airplane during the
landing is the location of its center of gravity. Tailwheel airplanes
in which the C.G. is relatively close to the main landing gear tend
to be more stable with respect to their ground looping tendency.
The Stearman’s C.G. location falls into this category, but I’m not
really sure if its location has much effect on negating the
Stearman’s propensity to ground loop. The Stearman is also
affected by the often forgotten consideration with respect to the
height of the C.G. location above the wheels. In the case of the
Stearman, the biplane configuration concentrates the weight of the
fuel in the center section, high above the wheels on the ground.
This additional moment to the height of the C.G. adds to the
reduced stability of the Stearman on the ground and is a
contributing factor to its well-known tendency to ground loop.
Both of these factors have an effect on the directional control of the
Stearman during a wheel landing, especially as the tail is
transitioning down to the ground. The P factor is present, although
in a much reduced amount since the power is at idle, and the
airplane will still have a tendency to want to turn to the left. The
high center of gravity is always present and there is not much that
can be done about that, it just is a constant factor contributing to
the characteristics of the airplane. All of this is coming into play as
the tail descends to the ground, exactly when the rudder is
beginning to lose its effectiveness. This probably is the most
critical time for the pilot during a wheel landing – maintaining the
directional control of the Stearman while in this transitional phase.
(But then again – maintaining directional control in ANY landing in
a Stearman is the primary problem.)
The above mentioned problem during the time period when the
tail is transitioning from its landing attitude down to the ground is
most likely the main concern of those pilots who oppose the use of
wheel landings and favor full stall three point landings at all times.
They will say, “The tail has to come down sometime, so you might
as well make a three point landing in the first place.” There is a
certain degree of validity to this argument. However, a good
competent, proficient tailwheel pilot can maintain control of the
airplane throughout the wheel landing with no problem and take
full advantage of the benefits it offers.
Stearmans have a fairly high wing loading and another technique
to take advantage of this particular characteristic during the
transition phase is to maintain the forward stick pressure that was
applied at touchdown. Don’t push forward further. This allows the
tail to lower a bit more quickly as the airspeed decreases. The
tailwheel will contact the runway before the rudder loses its
effectiveness, but still at a speed which will allow the application
of full up elevator without the danger of the airplane becoming
airborne again.
Another factor that can have an impact on the performance of a
wheel landing is the sitting position of the pilot in the cockpit. This
is equally as important in three point landings and take-offs as
well. It is important that the pilot’s body, and his head in particular,
be aligned with the centerline of the fuselage along the
longitudinal axis of the airplane. The common tendency of most
pilots is to lean to one side of the cockpit or the other, in order to
look around the side of the windshield and alongside the fuselage
in order to gain better visibility. Usually, pilots lean to the left side
as this is most natural since the left hand is on the throttle
quadrant on the left side of the fuselage and the right hand is on
the stick. The consequence of this leaning is that the control stick
is drawn to that side of the airplane, introducing up aileron on that
side, resulting with a wing that is forced down whether that’s
where you want it or not. So it is imperative that the pilot should
remain aligned with the centerline of the airplane to avoid this
unneeded control input. You should sit straight and your eyes
should look past the side of the windshield, between the wings,
along the side of the fuselage at an angle so as to focus on the
edge of the runway several hundred feet in front of the airplane. In
this manner you can judge your height above the ground, as well
as the drift and alignment of the airplane with the runway.
The height that a pilot sits in the seat also plays an
important role in the landing. In the WW II U.S. Navy training films
the Navy recommended that the seat height be adjusted so that
the pilot’s eyes are looking directly through the center of the
windshield. Personally, I find this just a bit too low for me, I prefer
to sit higher than that. Usually I sit as high as my seat will allow to
permit maximum visibility around the nose. Whatever seat height
position you are comfortable with and are accustomed to using in
your Stearman is what you should continue to employ while
making wheel landings. Don’t change it. That way your site
picture will remain constant regardless of whether you make a
wheel landing or a three point landing.
Your feet position on the rudder pedals also is important. Your
heels should rest on the floorboards with the balls of your feet on
the lower portion of the rudder pedals. Don’t have them raised up
high so as to get onto the brake portion of the pedals. While this
seems to be very basic and unnecessary to comment upon – rest
assured – the absolute last thing you want during a wheel landing
is to have the brakes being applied when you touch down.
As noted several times before, one of the prime uses for wheel
landings is in strong crosswinds. When landing in a crosswind it
is imperative that at touchdown all drift has been eliminated and
that the airplane is tracking STRAIGHT DOWN THE RUNWAY.
To accomplish this, apply the normal crosswind control
corrections; wing down into the crosswind with aileron to stop the
drift and enough opposite rudder to insure that the airplane is
going straight. This will result in touching down on the upwind
wheel first, followed thereafter with the other wheel. As the
airplane slows down continue to increase the aileron and rudder
input as necessary to keep the wings level and the airplane going
straight. Once the tailwheel is on the ground the steering will
become more positive, but be sure to maintain the crosswind
corrections and full up elevator to keep the tail firmly grounded.
Another method of making wheel landings that some pilots favor is
what I call the power-off, tail low landing. In this scenario the pilot
flies a normal approach, power-off and begins to flare as you
normally would for a full stall three point landing. When the tail
attitude is low, but not yet in contact with the ground, the pilot adds
engine power, or sometimes keeps the power at idle, and then
introduces forward control stick (down elevator) in an attempt to
“roll” it onto the runway.
This method completely nullifies the purpose and advantages of a
wheel landing which is to fly the airplane onto the ground at a
higher airspeed with a minimum angle of attack on the wing. In
this tail low method you place yourself into a sort of “never-never
land” upon touchdown and introduce into the equation all the
factors that are detrimental to maintaining directional control of the
airplane. The airplane is slow, the wing is at a higher angle of
attack, the rudder is beginning to lose its effectiveness, and power
possibly is being introduced which increases the P-factor and
adds to the left turning tendency. Throw in some crosswind and a
possible bounce on the touchdown and you are setting yourself up
for a trip off the side of the runway into the weeds – or worse. If
you choose to perform this type of wheel landing – you might as
well go ahead and make a full stall three point landing. You’ll be
a lot better off!
I have been very fortunate throughout my Stearman flying days in
that my home airport has three long grass runways and I have
spent most of my time enjoying the pleasures that grass provides.
As you know too well, the Stearman is a unique tailwheel airplane
and has some ground handling characteristics uncommon to
many other tailwheel airplanes. It really likes to ground loop and
you must remain ever vigilant upon every landing, whether it’s a
three point or wheel landing. The Stearman is no respecter of
persons or their experience level and is ever ready to humble the
unwary pilot. What exactly it is that makes it so is really hard to
pinpoint. The Stearman has a relatively narrow main landing
gear, a high center of gravity, large side fuselage and tail surface
areas and wheels with toe-in (cambered inwards). All of these
contribute to its willingness to jump up and bite you in the buttocks
(as Forrest Gump would say) at every opportunity.
Now take the Stearman to a paved runway and it will release the
“beast” that is hidden within. The Stearman definitely is a different
airplane on pavement than what it is on grass. Grass is the great
equalizer! For whatever reason, the tires just seem to reach out
and grab the pavement and bite into the ground. We have all
either observed, or most likely ridden through, landings on
pavement where the screech of tires is heard above the rumble of
the engine and the Stearman careens from one side of the runway
to the other until it is finally brought under control by its breathless
pilot. It doesn’t seem to get much better as your experience level
grows either. I have approximately 3000 hours of flying time in
Stearmans and still to this day, every landing on a hard surfaced
runway is preceded by a feeling of apprehension, a dry mouth, a
tightening of the sphincter muscle which induces an advanced
case of “pucker” that leaves me wondering if this will be the
Stearman landing that will finally jump up and grab me. I
constantly practice landings, both three point and wheel, on the
paved runways at airports near my home field to maintain my
proficiency. What all this rambling is leading up to is that I
personally prefer to make wheel landings in Stearmans on paved
runways. I feel that I have a greater degree of control over the
vagaries of the Stearman with a wheel landing as opposed to the
three point landing. Regardless of all the dire comments I have
just uttered, the Stearman is a wonderful airplane with a mystique
all its own and there is absolutely nothing more satisfying than
making a squeaker landing in a Stearman.
ADVANTAGES OF THE WHEEL
LANDING
Maximum controllability of the airplane through the touchdown
point.
§ Reduced susceptibility to being adversely affected by wind
gusts.
§ Improved visibility during the landing and rollout.
§ Ability to set the airplane on the ground at any airspeed (within
reason) above stall speed.
§ Ease of transition from one tailwheel type to another.
§ Safety in face of unknown factors such as:
Night landings (when visual acuity and depth perception are
reduced)
Overloaded airplane
Airplane with C.G. out of limits ( particularly an aft C.G.)
Airplane iced up such that exact stall speed is uncertain
DISADVANTAGES OF WHEEL
LANDINGS
§ More difficult to learn, master and maintain proficiency.
§ Uses a greater amount of runway during landing and rollout.
§ Potential for a bounced landing developing into a series of
bounces which may lead to a loss of directional control.
§ Potential for loss of directional control during the transition
phase while the tail is coming down to the ground.
§ Too much airspeed on approach – the airplane floats during the
landing.
§ Excessive amount of power during the landing.
§ Failure to apply forward stick pressure and reduce power
simultaneously at the time the main wheels touch the ground.
§ Excessive downward velocity (rate of descent) at touchdown.
(not enough power)
§ Getting impatient – diving at the runway or trying to force the
airplane onto the ground.
§ Too slow approach airspeed or leveling off in the flare too high –
the airplane settles fast onto the main gear and bounces.
§ Trying to salvage the landing after a bounce. (add the power
and go around and try it again)
COMMON ERRORS IN MAKING
WHEEL LANDINGS
There is one more final point to make. Wheel landings and soft
field conditions do not mix. If you are going into a soft field, make
a three point landing.
In summation, I would like to emphasize that the opinions and
preferences presented in this article are entirely those of the
author and in no way reflect any official position of the SRA. What
I have described reflects the way in which I was taught to fly
tailwheel airplanes and my observations gathered over 36 years
of flying and instructing in tailwheel airplanes. This is how I fly my
Stearman and how I teach my students.
I again would like to quote from The Compleat Taildragger Pilot
where its author, Harvey S. Plourde states, “No maneuver in basic
VFR flying is as poorly understood as the wheel landing. Yet, the
wheel landing is vital to the taildragger pilot’s safety. Without the
knowledge, experience, or skill to perform this maneuver, the pilot
severely limits the use of his taildragger to relatively benign wind
conditions. He also endangers the lives of his passengers, if, in
such ignorance, he ventures forth in conditions which give him 90
degree crosswinds in the 12 gusting to 18 knot range.”
Whether or not you agree or disagree with me concerning the
material and opinions I have presented in this article on wheel
landings, I believe that every Stearman pilot should know how to
do a wheel landing and should maintain proficiency in its
execution. To do so is to add another weapon into your arsenal of
skills to be called upon for use whenever needed. Whether you
choose to use the wheel landing, and under what conditions,
always will remain the option of the pilot. If you have never
mastered this skill or have let your wheel landing proficiency
become encrusted with rust, I would urge you to locate a good
tailwheel Flight Instructor in your area (preferably one with
Stearman experience) and get a few hours of dual instruction.
You’ll be a better pilot for it.
Tom Lowe is a Boeing 747-400 Captain for United Airlines based at
O’Hare Field, Chicago, Illinois. He served as the President of the SRA
for over 20 years and has owned and flown Stearman airplanes for over
30 years. He is a “Gold Seal” Certified Flight Instructor rated for
Airplanes, Single and Multi-engine Land; Instrument and Glider. He also
holds both the Advanced and Instrument Ground Instructor ratings. In
his spare time he specializes in Stearman, AT-6 and T-34 checkouts as
well as general tailwheel flight instruction.
Editors Note:
Supporting or alternate views on Wheel Landings vs ThreePoint
Landings are welcome for future publications of the Stearman flying
Wire.
http://www.cafutahwing.org/uploads/1/0/8/2/10827645/stearman_wheel_landings.pdf
Comments
Post a Comment