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.
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..."
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.