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Hi Ron,
I can understand your conclusion based on the information generally
available. I will share some additional information I have in Fred
Weick's unpublished notes because the "good of the fleet" is better
served now than by later publication.
"Power On Stall: The Ercoupe can be flown into a power on stall
by
rapidly pulling the control wheel back from level flight,
or from a full power normal climb. This rapid movement of the
control
wheel causes the energy due to forward speed to be
spent in climb, resulting in an angle of attack greater than the
minimum flight speed angle of attack. At this angle of attack
the Ercoupe wing is stalled and the airplane pitches sharply to
pick
up flight speed.
Even though the wing is stalled in the above maneuver it quickly
recovers and the ailerons used in lateral control become
immediately effective. Due to the inherent aerodynamic balance of
the
aircraft and its controllability at high angles of attack
autorotation, or a spin maneuver is impossible in a power on
whip-stall".
Elsewhere it is made repeatedly clear that the condition of "minimum
speed" or "minimum flight speed", power on or power off, is created by
slowly moving the control wheel back to the stop and allowing both
speed and angle of attack to stabilize. Fred continues:
"It is possible to stall the Ercoupe by pulling the aircraft into
a
high angle of attack with a rapid aft movement of the control
wheel from any speed above its minimum flight speed.
At a high angle of attack in which a smooth flow of air over the
wing
is broken up and becomes turbulent the center section
flow becomes turbulent first, due to the effect of center section
fillets. This turbulence moves back over the horizontal tail
reducing its down force which in turn causes the nose to pitch
down
permitting the aircraft to pick up normal flight speed.
Due to the fact that the center portion of the wing is most
affected
by the high angle of attack, the outer portions of the wing
panels remain stalled for only a short time. As a result the
ailerons
regain their effectiveness almost immediately."
Fred also stated:
"It is possible to stall the Ercoupe by pulling the aircraft into
a
high angle of attack with a rapid aft movement of the control
wheel from any speed above its minimum flight speed."
His description of the power-off stall was essentially identical,
additionally stating:
"SInce the wing panel tips keep within their smooth air flow
during a
hign percentage of the stall the ailerons are effective
in counteracting any roll which may occur as a result of the
stall.
Power-off stalls should not be precticed close to the ground since
approximately 200 feet are required in order for the
Ercoupe to get back into a normal gliding attitude"
So you can now see that the Ercoupe will NOT "stall" in the sense
contemplated by comparison with lesser designs, or as arbitrarily
"required" by new Sport Pilot rules. On the other hand there very much
does exist the Ercoupe airbourne "whip-stall"! Fred elaborated on this
too:
"Several accidents have occured because the pilot suddenly pulled
the
wheel back after a fast landing, and after the plane
ballooned into a high angle of attack he pushed the wheel forward
to
put the plane on the ground again. This caused the
wings operating at low speed and high angle of attack to lose
their
lift and as a result the plane struck the ground with the
nose gear taking sufficient impact to cause considerable damage."
Clearly this describes an inadvertent and uncorrected "whip-stall"
while landing. For any Ercoupe pilot in this situation, know that
recovery is not only possible but immediate upon application of
sufficient (full) power to reestablish normal flight ASAP. Then the
landing may be continued (remaining runway permitting) or a go-around
initiated, but the "drop" to the runway with insufficient flying speed
is averted as is related damage. The many wrinkled and replaced
firewalls on Ercoupes flying today are irrefutable evidence of
inadequate pilot instruction or understanding by owners prior and/or
present of Ercoupe stall characteristics.
The Ercoupe is one of the the most versatile designs of general
aviation, and the most forgiving to those who understand and respect
how truly unique it is. Every machine that takes to the air has a
"dark side" to its operating envelope that awaits the ignorant, the
lazy and the careless.
Regards,
William R. Bayne
<____|-(o)-|____>
(Copyright 2004)
--
On Nov 24, 2004, at 11:50 AM, Harden wrote:
> I am new to the Ercoupe. Based on the studying I have done, I have
> concluded that the only time the Ercoupe wing quits flying completely
> is when the wheels are on the ground! I have concluded that there is
> no such thing as an Ercoupe airborne stall. There is only an
> accelerating sink rate as the airspeed over the wing decreases and a
> partial wing stall starting at the root of the wing is created.
>
> The diagrams on page 13 of one of the owners manuals I have
> illustrates this rather well.
>
> Ron Harden
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