Tailwheel Crosswind Landing

On Tue, 30 Nov 2004 02:57:43 GMT, gregg wrote:

Are most/all J-3 tailwheels the same design?

I don't think I've ever flown a Cub (there have been four over the
years) that had an original Piper tailwheel. As Dudley mentioned, many
or most are Scotts.

all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

On Tue, 30 Nov 2004 02:57:43 GMT, gregg wrote:

I got on the brake right away and got her straightened out, and wobbled the
rudders and it got "back" into detent. But I'd like to know, mechanically
what's happening. If there's a drawing I could look at, that might help.

So would I!

Indeed, if anyone can point to a drawing, I'll post it on the Piper
Cub Forum www.pipercubforum.com -- copyright permitting


all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

Cub Driver wrote:

Indeed, if anyone can point to a drawing, I'll post it on the Piper
Cub Forum www.pipercubforum.com -- copyright permitting

For what it's worth, the Aircraft Spruce & Specialty catalogue has "exploded"
drawings and associated parts lists of Scott, Maule, and Lang tailwheels. My
Maule manuals have a large scale version of the drawing for the SFS-P8A
mechanism.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.

wrote in message m...
I am a long term lurker and have a question regarding landing tailwheel
airplanes in a crosswind. I have about 250 hours in a Piper PA-12 Super
Cruiser. The other day during a very routine crosswind landing I
started heading for the weeds faster than I new what to do.

Sounds like you might have been bit by that nastly little beast called
"complacency". To me, the hint is "a very routine". I think you've
learned
that ain't necessarily the case:-) I've always found that a light, but
variable,
wind to be about the most difficult to land a tailwheel airplane in.
I've been
surprised by swings at least a few times on those days. When the wind
is strong
and from the left, for example, you know it's a crosswind from the
left. In light winds, it may be a left crosswind now, but a second
from now??

I had a fairly gentle cross wind from the left. I had cancelled out all
sideways drift by lowering my left wing and aligned the plane with the
runway with right rudder. At touchdown, everything seemed perfect. That
is when all hell broke loose. As soon as I touched down, I started a
very fast turn to the right. At one point I was headed right between
two runway light. As I was deciding that "between" was not a bad place
to be, I finally managed to straighten everything out and managed to
stay on the runway.

Sounds like you made a good save. Good job! As others have noted,
checking the tailwheel
for problems sounds like a good idea. About the most experienced
tailwheel
pilot I've known (with over 10,000hrs of tailwheel dual given) says "a
well
maintained tailwheel is the cheapest insurance you can buy". Having
said
that, I wouldn't be surprised if there's nothing wrong with it. A wild
guess
would be that the left crosswind died just before you touched down. At
that
point, your left wing down caused you to drift to the left and that,
combined
with the right rudder, caused the swing. In the end, sooner or later I
think
we'll all get a good swing (I know I have:-) and you pulled off the
save, which
is great. I suspect your save will happen more quickly next time.

Don't know if this'll help, rick
ps: The same instructor mentioned above, used to say that the most
inportant
pre-landing check he did was to "shake his head and remind himself
it's
time to focus on landing" when on final.

wrote in message m...
I am a long term lurker and have a question regarding landing tailwheel
airplanes in a crosswind. I have about 250 hours in a Piper PA-12 Super
Cruiser. The other day during a very routine crosswind landing I
started heading for the weeds faster than I new what to do.

I had a fairly gentle cross wind from the left. I had cancelled out all
sideways drift by lowering my left wing and aligned the plane with the
runway with right rudder. At touchdown, everything seemed perfect. That
is when all hell broke loose. As soon as I touched down, I started a
very fast turn to the right. At one point I was headed right between
two runway light. As I was deciding that "between" was not a bad place
to be, I finally managed to straighten everything out and managed to
stay on the runway.

In talking to my mechanic as soon as I touched down (I was sure there
was a mechanical problem), he figured that with all of the right rudder
needed to keep things straight, that my tailwheel just sent me to the
right once it touched down.

My question is, what was really going on here? Should my tailwheel
have released (castored) when I touched down? Your thoughts are greatly
appreciated.

The tailwheel probably shouldn't have castored but usually has some
spring difference. I have had the tailwheel castor after landing.
Everything seems fine until you get down to about 10 knots and then
find you have 100% no directional control. Luckily, I got back on the
brakes soon. You want to ensure the castor doesn't break loose too
soon.

Could it be possible that you didn't have the nose properly lined up
so you actually touched down a bit in a crab? That can cause such
problems.

-Robert, tailwheel CFI

What I would really like to know, and don't seem to find anywhere, is
how is a tailwheel like a Scott SUPPOSED to work. In other words, is
the released condition only for performing tight ground manuvers or is
it expected to release or castor in other situations? Does it
release differently when there is weight on the tailwheel than when I
have the tail raised during preflight inspection? Overall, I would say
the functioning of entire tailwheel mechanism is a little bit of a
mystery.

The tailwheel should only castor when on the ground when sufficient
breakout force is exerted. In flight, the wheel detent should engage and
the wheel should move with the rudder. The tailwheel springs center the
tailwheel when the weight is off the wheel.

Thomas Ploch wrote:
What I would really like to know, and don't seem to find anywhere, is
how is a tailwheel like a Scott SUPPOSED to work. In other words, is
the released condition only for performing tight ground manuvers or is
it expected to release or castor in other situations? Does it
release differently when there is weight on the tailwheel than when I
have the tail raised during preflight inspection? Overall, I would say
the functioning of entire tailwheel mechanism is a little bit of a
mystery.

Thomas Ploch wrote:

What I would really like to know, and don't seem to find anywhere, is
how is a tailwheel like a Scott SUPPOSED to work. In other words, is
the released condition only for performing tight ground manuvers or is
it expected to release or castor in other situations? Does it
release differently when there is weight on the tailwheel than when I
have the tail raised during preflight inspection? Overall, I would say
the functioning of entire tailwheel mechanism is a little bit of a
mystery.

The Maule tailwheel has two locking pins between the rudder yoke and the wheel
yoke. The top of the wheel yoke has a cam that rests against these pins. If
enough sideways turning pressure is applied (as is the case when you use
differential brake to make a sharp turn), the cam pushes the pins up and the
wheel yoke castors. Since the cam has to push the back of the aircraft up to
move the pins, the less weight on the tailwheel, the easier it is to make the
wheel castor.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.

(Thomas Ploch) wrote in message . com...
What I would really like to know, and don't seem to find anywhere, is
how is a tailwheel like a Scott SUPPOSED to work. In other words, is
the released condition only for performing tight ground manuvers or is
it expected to release or castor in other situations? Does it
release differently when there is weight on the tailwheel than when I
have the tail raised during preflight inspection? Overall, I would say
the functioning of entire tailwheel mechanism is a little bit of a
mystery.

It will caster if it's forced past a certain angle of pivot. An
internal mechanism disengages the steering arm from the wheel fork.
This is designed to occur at a point well past the angle that the
rudder/wheel steering springs will take it at full rudder deflection.
You wouldn't want it to disengage before full rudder travel,
certainly, as you might be trying to stop a bad swing on the runway
using the rudder, and the wheel needs to be engaged.
The wheel should disengage freely enough if you are taxiing and
apply full rudder and some brake. The springs will let the wheel pivot
far enough to let the lock disengage. Weight on the wheel shouldn't
make much difference, except that the steering spring length might
shorten a bit and make disengagement easier when the tail pushes down
on the wheel, flexing the tailspring.

Dan

(Thomas Ploch) wrote in message . com...
What I would really like to know, and don't seem to find anywhere, is
how is a tailwheel like a Scott SUPPOSED to work. In other words, is
the released condition only for performing tight ground manuvers or is
it expected to release or castor in other situations? Does it
release differently when there is weight on the tailwheel than when I
have the tail raised during preflight inspection? Overall, I would say
the functioning of entire tailwheel mechanism is a little bit of a
mystery.


It should take enough force that a cross wind landing SHOULD NOT
unlock it. You really need it locked during landing because its your
only way to control direction once the air stops flowing over the
tail. When they start to wear out, they may break loose too easily and
result in possible ground loops. The only time I ever ground looped a
taildragger was as a result of this. The outside main did come off the
ground but I was slow enough that the wing tip did not touch the
ground. I should have been quicker on the brakes.

-Robert