pilot report the Piper Cub
Setting the Baseline...the Piper Cub
by
Budd Davisson
This sentence begins a whole new series for
Sport Aviation and the Experimental Aircraft
Association. You might call it Comparing the
Classics. Or Classics Explained. Actually,
you can call it anything you want. We call
it an educational reference for those
thinking about diving into the wide variety
of post-war classics. Since over 35,000
airplanes were produced in 1946 alone, we
certainly have plenty to chose from.
Not so many years ago,
evaluating post war classics would have been
unnecessary since every pilot had flown most
of them. That's no longer the case. Nearly
half of the pilots flying today learned in
the last 15-20 years. How many do you
suppose learned in a Cub? Or had a Cessna
120 available to rent for $8.50 an hour?
Another sobering fact:
Just short of half of the EAA members now
active joined since 1985. Nearly 70% joined
since 1980. To them the classics fall right
in with antique airplanes are just as
foreign.
The goal of this series,
which will eventually touch on each and
every airplane of the period, is to explain
those airplanes in commonsense terms. We
aren't going to get into "stick force per
"G"" or "spiral divergence" or any of the
other 3-D tech-talk we've come to associate
with well-done pilot evaluations. We want
people to understand how these airplanes
compare to airplanes they either have
already flown, or which are readily
available for comparison.
Citabria and C-152 are
the Datum Points
Since so many classic aircraft have the
little wheel at the back, we selected the
Citabria as the base-line airplane for those
handling and performance factors having to
do with ground handling. The Citabria is the
only tailwheel airplane which is readily
available at flight schools and even it is
sometimes hard to find.
We selected the Cessna
152 as the datum for all other comparisons,
once off the ground, unless otherwise noted.
The comparisons will be in the vein of
"...during roll-out the airplane tends to
wander a little more than a Citabria..." or
"...the ailerons are a fair amount heavier
than a C-152, but the airplane responds to
aileron input much more quickly..."
We'll put these
comparisons into a chart which rates a
number of performance and handling factors
against the datum aircraft. They will
represent zero and the evaluation aircraft
will be rated plus (better, easier or
quicker) or negative (worse, slower or
harder) on a scale of 1 to 5, plus and
negative.
The J-3 Cub
To kick this thing off we thought we'd
evaluate what used to be the airplane to
which all others were compared, the J-3 Cub.
There are bound to be a
lot of folks out there who are saying,
"What? Another Piper Cub pirep? That's so
basic it's like explaining dirt. Everyone
has flown a Cub!"
Only a few years ago
would have been a valid statement but go
back and look at the earlier statistics.
Between the total take-over of the tricycle
gear trainer and the exploding prices of
Cubs, with very few exceptions, if you want
to fly a Cub, these days, you have to buy
one. They have become so popular because of
three basic facts: They are very nostalgic,
they are lots of fun, they are cute as a
bug.
Mechanical Description
We're going to ignore the history of the
airplane, since everyone knows it and get
right down to the nuts and bolts.
The fuselage of the Cub
is welded steel tubing with the landing gear
being a welded "V" with external bungee
springing. The wings are attached right in
the middle of the cabin where the fuselage
truss comes together in an inverted "V".
This means the entire top of the cabin and
the windshield framing is made of
light-gage, bent steel "U" channels which
are often bent and filled with extra screw
holes.
As with all aircraft of
its type, the fuselage is prone to longeron
rust at the tail post from water running to
the low point. Remember, these airplanes
weren't always hangar queens, so most have
had, or need, repairs in that area.
Another area of corrosion
concern is the struts. The original struts
were unsealed and could rust internally at
the bottom end where moisture collects. That
problem, combined with the integrity of the
strut forks themselves, is why there's an
inspection AD on them. That's also why so
many people simply buy new, sealed struts
from Univair and be done with it.
The wings used what was
to become the standard Piper rib
construction in that they never went to
stamp metal ribs as did Taylorcraft or
Luscombe. Piper ribs are fragile trusses of
"T" sections formed by folding extremely
thin aluminium into the required "T" cross
section. They are strong, but there are a
lot of pieces involved and, once broken,
require patience to patch in a clean manner.
Wing spars come in two
varieties, wood and extruded aluminium. Wood
spars are seen in every variation from a
single plank, to laminated, to laminated
with the individual laminates made up of
different length pieces scarfed together.
Properly varnished and cared for, all
variations are fine, but need inspection
before buying. Beware grey, flaking varnish
or dark wood. This is an indication moisture
may have found its way in.
The post-war aluminium
spars are modified "H" sections and need
only be inspected for corrosion on the top
side of the lower caps which can trap
moisture. Also inspect for extraneous screw
holes.
The original leading
edges were .016, soft aluminium and won't
take much abuse before assuming the visual
character of a ploughed field. When
restoring them, most opt for slightly
heavier, harder material which makes a
tremendous difference.
Tires and brakes are both
strong and weak points for the Cub. The
original expander-tube brakes use an
inflatable doughnut to force a multitude of
small blocks against the drums. As brakes
go, they stink. That's also their strongest
point because the airplane needs almost no
brake for normal operations and the original
brakes can't overpower it. The brakes
biggest problem is that they are very
expensive to rebuild. The tubes and blocks
have sky rocketed. So have the original 8.00
x 4, smooth tires. This is one reason so
many have gone to Cleveland wheels and
brakes and 6:00 x 6 tires. That amount of
brake, however, is far more than the
airplane actually needs. With expander tube
brakes it's hard to brake it hard enough to
pick up the tail. With Clevelands it will go
over on it's back in a heart beat.
The usual engine is the
Continental A-65, which is probably the most
important thing to happen to light aviation.
This engine made little airplanes practical.
If even remotely maintained it will start
and run beautifully. Magneto coils are just
about the only reason the engines won't
start easily. TBO is a little vague, assumed
at about 1,200-1,400 hours, but think how
long it takes to put 1,000 hours on an
airplane like a Cub.
The engines are still
relatively inexpensive to overhaul mainly
because we haven't yet reached the bottom of
the barrel which was originally filled to
overflowing by the military. The bottom of
the barrel, however, is beginning to peek
through.
The most common
conversion to the airplanes is the simple
replacement of the A-65 by a C-85. The
additional horsepower makes the airplane
into an entirely different animal. It still
has its basic pasture goodness but with very
spirited performance. Unfortunately, the
85's and C-90s are getting increasingly
harder to overhaul. In fact, there is an STC
to put the more common 0-200 crank into the
C-90 case.
From a performance point
of view, a metal propeller is preferably
because it lets the engine reach peak RPM,
but the wooden prop is much prettier.
Neither is cheap.
Flight
Characteristics.
To fly the airplane, you have to get in
it, which in a Cub, isn't as easy as it
sounds. You have to master the entry-dance.
Right foot in the step, lean forward over
the front seat, left foot past the stick,
bring right foot in, lower yourself
backwards. There that wasn't so hard, was
it? The canvas sling back seat is much more
comfortable than the front seat.
Over-average height folks will be folded
like a pocket knife in the front seat.
If it's your first time
in a Cub, you'll think you're sitting at an
impossibly steep tail down angle. And you
are. Few Classics have such a tail down
stance, but the feeling of blindness is
largely one of perception. Because the
airplane is so narrow, only a small wedge is
taken out of the visual field.
Unfortunately, it's directly in front of
you.
Contact! Brakes! Mags
hot!. A good engine will catch on the first
blade. If it's your first flight, close the
door, as it causes some perceptual
difficulties because, with it open, you can
see so much better out of the right than the
left.
The first thing you'll notice in manoeuvring
on the ramp is how hard the stupid heel
brakes are to get at because they're
snuggled under the seat. That's good. That
way you won't be tempted to use them on
landing where they aren't needed.
"S" turns are absolutely
necessary to see ahead, but they also give
you rudder practice. For some reason, maybe
it's the light tail, the Cub is quicker to
respond to the rudder than most light
taildraggers, including the Citabria. It's
only a minor difference but noticeable. On
takeoff and landing it makes it a little
easier than some to over-control.
By all means, do a full
360° turn to clear the pattern before
taxiing onto the runway. The pilot sits so
far back in the airplane vision is sharply
limited by the narrow tunnel of the fuselage
and the wings and a full turn is mandatory.
Lined up, suck the stick
back and move the throttle smoothly forward.
The noise turns into kind of a rattling roar
and the airplane will begin accelerating at
about the same rate as a heavily loaded
Cessna 152. As soon as the power is full on,
ease the stick smoothly forward and bring
the tail up. If you're of average height you
won't quite be able to see over the nose but
the visibility improves drastically anyway.
There is so much airplane between you and
the outside world, there is no doubt when
the nose tries to move.
The rudder becomes
effective as soon as the power is on and
you'll notice the tail moves each time your
foot does. The airplane is very stable
directionally. In fact, if there is no
crosswind, the tail won't move sideways on
its own. If it is, stop moving your feet for
a second to see if it isn't you causing the
movement.
Even on a calm day, the
Cub will fly off the ground long before you
can get in serious trouble. If there is just
a few knots of wind on the nose, it'll leave
the ground almost as soon as the tail is up.
Solo it leaps off. Dual it takes much
longer. The airplane really reacts to extra
weight.
A Cub
telegraphs everything it does, especially
when it is getting too slow to climb. Play
with the speed a few knots at a time, while
climbing, and you'll find a point where you
can actually feel the drag building, control
effectiveness falling off and the climb
slowing as the nose is brought up. Every Cub
likes a slightly different climb speed,
usually because the airspeeds are so far
off, so just feel it out.
With one on
board, a 65 hp Cub in 75 degree air may give
as much as 400-500 fpm. 85 hp adds at least
another 200 rpm and a C-90 makes you feel
like you have a fly-weight tiger by the
tail. The increased power is also very
noticeable on takeoff acceleration.
As you level off and the
speed rockets ahead (read that with a lot of
sarcasm), be suspicious of any speed above
80 mph indicated. 75 mph is a pretty
standard Cub cross-country speed.
The controls in a Cub set
the standard for most of the long-wing
Pipers to follow. There's a fair amount of
system friction because everything is cable
and pulley operated. These days the friction
is almost always aggravated by at least one
pulley that isn't turning. The friction
helps build the perception that the aileron
forces are heavy, but they really aren't.
The airplane responds very much in
proportion to the amount of stick put into
it and will actually roll into a bank much
faster than people expect, if they put their
shoulder into it. The pressures are much
lighter and the response higher than a
Citabria, for instance. Compared to a C-152,
they are about even, although it's hard to
compare pressures between a stick and a
yoke.
Elevator pressures and
rates are matched to the ailerons and you
won't even notice the rudder because it
mixes in so naturally. And you will need
rudder. The airplane has noticeably adverse
yaw and the pilot who doesn't coordinate
will polish the bottom of his jeans smooth.
That's one of the things that makes it such
a great trainer
Stalls in a Cub can be
what you make them. Normally, they are soft
and floppy with very little edge to them.
Feeling goes out of the controls in such a
noticeable fashion, as the stall approaches,
your hand will tell you something is
happening, if nothing else does. If you have
the door open, the bottom half will begin to
float up as the stall is approached. If you
crowd the stick back hard or persist in an
exaggerated nose-high attitude, it will
pay-off, drop the nose and make you light in
the seat.
Coming in to land, power
back opposite the end of the runway, you
risk a stretched muscle as you lean forward
trying to get the carburettor heat on the
right side wall by your foot. Crank, crank
the elevator trim and the airplane will hold
an approach speed of 60 mph by itself. It
can fly the approach much slower, but
there's no reason to.
The Cub is dirtier than
most of its contemporaries so its glide
slope is a little steeper. It comes down
even faster than a Citabria or 152, but at
such a slow speed, the pattern is still not
super-tight or rushed. Also, there is no
such thing as "too high" in a Cub, as it is
one of the best slipping airplanes ever
invented.
A secret for getting
consistent, good landings: Break the glide
just a little higher than you think you need
to. If you fly it into ground effect
expecting to burn off speed and three-point
it, you'll almost certainly touch the mains
before getting the tail down. For some
reason, Cubs appear to have less ground
effect than many airplanes.
The nice thing about a
Cub landing is that it happens at a
near-walk. Actual touch down is around 35
mph, so even if your technique is sloppy,
everything is happening so slowly you have
all day to set it straight. If you don't
have much tailwheel time, try not to think
about it. Get the airplane on more or less
straight and it will roll more or less
straight. Start fighting the rudders simply
because it's a taildragger and you think you
should be doing something, and it will do a
slow motion dance. Best advice in landing a
Cub is to make sure it is straight and not
drifting and leave it alone after touch
down. There's a reason for the saying
"...lands easy as a Cub..."
A word about
crosswinds and gusts: The airplane is really
lightly wing loaded and rides thermals and
gusts like a cork. It will, however, handle
much more crosswind than most think it will,
providing the pilot has a firm hand and a
good head. It can, however be overwhelmed.
Winds which are an annoyance in a 152 are a
challenge in a Cub. In a pinch, diagonal the
runway, or turn into the wind at the end of
roll-out. Then you have to worry about
taxiing. It's entirely possible to land in a
wind which is too high to taxi in. In that
case, keep the nose into the wind and wait
for help to walk you in. More than one pilot
has had to coast past the hangars at fifty
feet with the door open and the throttle
back while yelling for help before landing.
One common J-3 variation
seen, by the way, is the Reed Clipped Wing
conversion which removes 40 1/2" from each
wing root. To many, this makes a good
airplane even better. Besides making it
capable of loop, roll, spin, type of
aerobatics, with 85 hp, it will cruise at
nearly 90 mph and its entire handling
package tightens up, becoming quicker and
more crisp. It will also handle much more
wind with the short wings.
Market forces almost
always place a price premium on products
which have proven themselves both in
aesthetics and use. No where is this more
obvious than in the J-3 Cub, as it is easily
the most expensive airplane in its category.
This is a distinction many believe to be
well deserved.
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