Hi Daniel,
1. Pages 12 and 14 of the Parts Manual show the gear differences (do
not picture the prewar double-fork trailing arms, though).
2. Five possible "problems" come to mind as to takeoffs departing a
short grass field after correcting a tail low condition:
a. The grass is longer on the day of observation than it was before
(more
drag on the wheels/tires = less acceleration) ;<)
b. The departure weight of the airplane is greater on the day of
observation
than it was before (more weight takes a greater angle of attack to
lift).
c. The Ercoupe has a metal prop which, with other modifications, may
move the CG enough forward that rotation is less responsive (and
decisive) than with the CG as the plane came off the production line.
d. The engine is not putting out rated horsepower such that, again,
rotation
is less responsive and decisive than when the plane came off the
production line.
e. The pilot is relying on a false "seat of the pants" recollection
of how the
bird should "feel" instead of believing the indicated airspeed
numbers
that worked before will continue to work.
3. All of the preceding are amplified if:
a. The coupe is a 415-D model limited to 9º up elevator.
g. A cruise prop has been fitted and maximum horsepower is not
available
at actual takeoff RPM.
4. It is my belief that having the trim set to the "Cruise" position
for both landing
and takeoff results in the highest possible "up" elevator
effectiveness for a
given elevator movement and trim tab. To such extent as this is true,
rotation
would be more responsive (and decisive) at any indicated airspeed.
5. The only "position change" available for the elevator rod I am
aware of is for
airframes fitted with the split elevator AND the low speed warning
cushion
spring.
The only thing changed is the power-off glide speed with the yoke in
the
position where the spring's resistance is first felt. There on only
one
"correct" position, as determined by such glide speed; see ESM 35A.
Regards,
William R. Bayne
.____|-(0)-|____.
(Copyright 2010)
--
On Apr 30, 2010, at 12:30, Daniel Arditi wrote:
Hi group,
I have two questions regarding this topic about
raising the Cupe's tail:
1.- Does anyone have some photographs so we can see the differences
between these two models (earlier ones and later models) ?
2.- This one has to do with the flight difference experimented after
raising the tail to the correct high: For those who got accustomed in
taking off and landing with a "low tail" (especially during take off):
Did you have any problem or something to tell about the difference? I
once heard that after rising the tail, and on a short grass field the
pilot had to abort a take off because he felt uncomfortable as it was
a bit hard to rotate in that same field as he used to operate ?
Has the rod that commands the elevator a possibility to change to a
second (more sensitive) position ?
Thanks in advance
Best regards
daniel arditi
Grupo Ercoupe Argentina
