Hi Bart,
Your post made my day. It tells the "rest of the story" that I was
trying to alert people to.
I talked about landings, and you talked about takeoffs. (see below).
Obviously in the
process of taking off, using the brakes to drop the wink is not an
option.
Without regard to the skill of the pilot, there is the period of
acceleration from about 45 to
65 mph that a tail-low bird may have a wing picked up by a gusty. I'm
not convinced at
those speeds there is always sufficient elevator authority to compress
the taxi spring
enough with forward yoke pressure to achieve the angle of attack of the
wing originally
designed. The pilot has just transitioned from pilot to test pilot!
Accordingly, it is in this situation that a low-tail couper can find
himself/herself departing
the runway if the plane weathervanes (directional control with the yoke
by the pilot
becomes unpredictable and unreliable) before sufficient speed is
available to fully lift
off and fly.
It doesn't matter whether the tail low condition is the result of
substituting a 5" nose wheel
and tire for a 4" nose wheel and tire (lengthens nose strut) or is the
owner is operating
with the original 1946 rubber donuts (now compressed so as to shorten
the effective
"taxi length" of the main gear legs).
It is important to get the plane's sill level again since each such
takeoff is literally a "roll of
the dice". It is desirable to replace the donuts (or repair the
Bellevilles) if these do not
take up all the space (no more than 1/16" space in the "stack" with the
clip in place, and
then add whatever spacer thickness is necessary to get the sill back to
design (level)
condition.
And always remember that our own Bill Coons did the head work and the
leg work to get
the spacers accepted by the FAA.
Regards,
WRB
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Begin forwarded message:
From: William R. Bayne <[email protected]>
Date: March 16, 2009 20:11:24 CDT
To: 'Ercoupe Tech Forum' <[email protected]>
Subject: Re: [ercoupe-tech] Re: snubber cable HOW THIS ROUND STARTED
Hi Dan,
Tail height becomes a non-issue for a competent Ercoupe pilot who
lands at minimum speed. The plane is through flying and will behave
regardless. Likewise the minor delay in steering authority from a
snubber cable.
Don't check for "tail height", but for the "level sill" of a properly
rigged and airworthy airframe.
That said, there is genuine danger lurking for someone new to the
Ercoupe without competent instruction and "low tail" syndrome, landing
at or above 65 MPH TAS in gusty crosswinds. The Ercoupe Instruction
Manual will NOT tell them that if (1) a gust lifts a wing (the low
tail allows it to be at sufficiently positive angle of attack to
"self-rotate"), (2) they don't immediately apply the brakes to dump
speed and kill the lift and (3) the bird then "weathervanes", they can
be in deep yogurt very, very fast without understanding what happened.
This can happen VERY quickly.
If their seller did not know or explain these things, their mechanic
likely will not be of help. Clairvoyance is not a requirement to
exercise the privileges of the private pilot license, and there is no
placard to warn new owners of this danger in advance.
The "low tail syndrome" is a phenomena which arises from (1) lack of
proper attention to the main gear rubber "taxi springs", or "donuts,
(2) installation of a 5" nose wheel and tire for the previous 4" nose
wheel and tire, and (3) installation of the Forney-style double-fork
nose wheel support.
If they are scared sufficiently by the experience to sell the plane,
we have another unenlightened pilot that will "bad-mouth" the Ercoupe
until the day they die without ever having understood that THEY
brought on the problem by (1) choosing to land fast (normally not a
problem), and (2) not having re-established the level sill condition
that the plane had when delivered (which makes landing too fast risky
in gusty crosswinds).
Good summation overall!
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
--
On Mar 27, 2009, at 19:08, bbartsey wrote:
I had my coupe in for its annual and after bitching for a year about
the crosswind landing/takeoff characteristics of my coupe, I had the
spacers installed on the main gear. My, my. What a difference that
made.
I took off from Naples, FL in a fairly tame crosswind to go to have my
annual done and the last part of the takeoff roll was a
wants-to-weathervane-and-opposite steering-raises the upwind
wing-yahoo maneuver. I even commented to the tower about Ercoupes
not having rudder control because I had become airborne over the grass
on the right side of the runway. Looked tacky and I wanted to
apologize.
Well, sir, after the spacers were installed, the upwind wing does not
want to raise when downwind steering is used and the plane as as
docile as a kitten now in crosswinds. Today, we had winds 30-45
degrees off runway heading gusting 25 to 30 and the landing was like
on a calm day. I can't believe the difference.
Point is, if your Coupe looks a little like a tail-dragger, get the
spacers to level it back up. You'll get a quantum jump in crosswind
handling characteristics.
Bart
