I would like to "weigh in" even stronger on Ed's desire for a level
sill.
The sill is the official "leveling" reference. All coupes until the
415-E Model (with the 4" nose tire) came out of the factory "sitting"
level (per the sill).
The introduction of the 5" nose wheel (and wheel support) on either
"steel" or Electrol nose strut containing the standard taxi spring
raised the nose of the plane in proportion to the increased diameter of
the nose wheel/tire. This tipped the sill backward and lowered the
tail while increasing the static angle of attack of the wing.
No longer could the plane could be put on the ground at almost any
speed with confidence that it would stay there unless the yoke were
pulled back, because of the increase in the angle of attack of the
wing. During early Forney production a new double fork was introduced
which definitely resulted in lower tail height and a sill not level.
Univair's double fork and 5" nose wheel kit was better engineered, in
that it incorporates a shorter taxi spring that compensated for the
bigger wheel and tire (see Parts Manual p. 21).
I believe the ONLY credible reasons for Ercoupe difficulties with
crosswinds is this increase in the static angle of attack of the wing,
whether from poor maintenance of the rubber donuts OR a 5" nose wheel
and tire (excepting Univair's kit) installation. There are
combinations of adverse crosswind gusts before liftoff and after
touchdown (while still on the ground above "minimum speed") that can
and do pose a genuine risk to the most proficient pilot of a low tail
coupe.
I am aware of NO instance where an Ercoupe (et al) with level sills has
shown questionable flight characteristics in crosswinds. That is
decidedly NOT the case with droopy-tail coupes, as Ed points out.
Regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2010)
--
On Apr 30, 2010, at 22:01, Ed Burkhead wrote:
In response to Kevin's message: Please check out the landing gear
discussion in Stick and Rudder.
What you say is valid but so is Langewiesche's point about the tail
dragger
gear being a takeoff gear.
All in all, I really want my the window sill level on the ground on any
Coupe of mine! I could handle quite short fields with my climb prop
and, in
a crosswind, the behavior of a tail-drooping Coupe can get into the
dangerous range.
Ed
