Bart asked:
> Just one thing puzzles me about these comments on crosswind landings.
With the mains on
> the ground, you say the force on the main gear aligns the airplane with
the runway prior to
> nose wheel touchdown. Then why does the airplane tend to weathervane into
the wind with
> the mains on the ground and the nose in the air? Makes for some exciting
excursions into
> the grass, don't you think?
Dan,
When the mains are on the ground and the nose in the air, the side pressure
of a crosswind on the tail WILL push the tail sideways and cause the plane
to weathervane.
On a landing roll, after touchdown, you do want to make sure the nose wheel
comes down (and you can't hardly prevent it) to give you nose wheel
steering.
On a takeoff roll, if the crosswind is strong enough to cause weathervaning
problems, then the nose wheel should be left firmly on the ground till
there's enough airspeed that, when you pull the plane off the runway,
there's no chance of it settling back down onto the runway.
I'm inclined to go with the designer. Fred Weick thought the snubber cable
should not be used.
WITH **NO** SNUBBER CABLE:
The mains touch first. As the main gear shock
absorbers compress, the nose gear touches no matter
whether you hold the nose off moderately or radically.
When the nose wheel does touch, the nose wheel
TURNS instantly to line up with the direction of
motion (as long as the pilot does not inhibit this turn
by a firm grip on the yoke (or rudder pedals). This means
there's no side load on the nose gear other than an instant
surge that has been shown, though bunches of Ercoupe
crosswind landings, to not damage the gear.
As soon as the nose wheel finishes its instant turn,
nose wheel steering becomes available. The weight
of the aircraft on the mains will cause the aircraft to
pitch downward, dumping lift and bringing full (or
nearly full) weight onto the nose gear, thus insuring
full nose wheel steering.
WITH A SNUBBER CABLE, all these same things happen
though, if you manage nearly zero the vertical speed
at touchdown, the aircraft might do much of its turn
to line up with the direction of travel over the ground
BEFORE the nose wheel touches.
Finally, WITH NO SNUBBER CABLE, the nose gear can extend fully.
In flight, with the nose gear fairing reinstalled, the
aircraft gains very close to one (1) mph as carefully
measured, according to Fred Weick.
Upon landing, the nose gear has its full shock absorbing
ability with increased ability to resist damage to the
nose gear and engine mount.
Summary:
If you can reliably land with near zero vertical speed, then having a
snubber cable has an advantage in lowering side stress on the nose gear and,
due to your skill, you have no risk from the degraded shock absorber.
If your landing skill is not in the expert range, your nose gear may benefit
more from the additional shock absorber effectiveness than from the fraction
of a second to couple seconds delay in nose gear touchdown.
If you want the extra one mile per hour, remove the snubber cable and ensure
the nose gear fairing is properly installed.
Here are other articles about crosswind landings in Coupes:
http://edburkhead.com/Ercoupe/coupe_flying.htm
JMHO
Ed
