Jerry,
Your G model has (or should have) the "split elevator".
If the air speed indicator is accurate and if the plane is rigged
correctly it WILL NOT "fall out of the sky about 72 mph". That's well
above the "high sink rate" range. As a first step, I suggest you take
a GPS aloft, slow the bird to 73 mph indicated, and compare the two
readings. The Approved Flight Manual for Models 'E' & 'G' on p. 11
showed a "true airspeed" of 60 mph when 56 mph was indicated, 70 mph
when 67 was indicated and 80 when 78 was indicated.
Landing the various coupe models at the speeds Ed stated is not rocket
science, but it does presume an accurate air speed indicator and
proficiency in accomplishing an appropriate sequence of events. In my
own case, I had absolute confidence in the Ercoupe Instruction Manual
and "just did it"; but some are more comfortable having these things
demonstrated before they can proceed.
As a rule of thumb, the indicated airspeed is higher that the truth
below 100 mph and lower than the truth above. For all values above
"minimum speed" the error is 3 mph or less. That's not enough to get
anyone in trouble that has any "feel" whatsoever for the aircraft in
flight.
The "stall" in an Ercoupe should be a gentle drop of the nose to pick
up a few miles an hour and altitude loss should be minimal. If the
yoke is moved back too rapidly near the minimum speed, the resulting
"whip stall" is much more abrupt and more altitude is lost. This is
something best worked out at altitude and not just above the runway.
Should a low time pilot "balloon" (suddenly climb and find themselves
5-10 feet off the runway with little forward speed), immediate
application of full power restores lift to the wings with minimum loss
of altitude. Hesitation, however, will likely result in a hard landing
with possible damage.
Most of us have a WW II training base with long runways within flying
distance that is now municipally owned and operated. Go there and make
any necessary arrangements to practice slow flight and touch and goes
with plenty of hard surface available.
With a 5,000' runway, practice slow flight...holding the bird one foot
off the pavement at the slowest speed possible. Before the coupe can
"stall", it will sink. So long as you can keep the bird from touching
the runway surface with the yoke at a constant speed you absolutely
cannot stall while in "ground effect" at that speed. Keep reducing
that speed in two mph increments and eventually you will be able to fly
an approach arresting descent one foot off the runway and fly the
length of it without touching down.
Next time around, at that same constant speed move the yoke back a bit.
If the plane goes up, you weren't flying slow enough. If it sinks to
the runway surface, it will be your slowest, smoothest landing ever.
At the moment of touchdown, THAT is YOUR plane's "minimum speed"
occurring just when you want it to...at touchdown. Jot it down for
future reference.
If you go back up to pattern altitude and establish that "minimum
speed" you will probably find that you are sinking like a stone.
That's why the landing approach is not flown at that speed in an
Ercoupe. The G model has a power off stall speed of 56 mph. The low
speed warning cushion (spring) is supposed to be felt at 60 mph.
The 415-D Approved Flight Manual on p. 10 suggests an approach speed of
75 mph and its power off stall speed is 58 mph. The manual for the E &
G models refers you to the Ercoupe instruction Manual, and it suggests
approaches be flown between 60 and 70 mph. At or near 1400# the higher
value is more appropriate.
Remember that 70 mph (true) is your "Best Rate of Climb" (see Climb
Data, p. 10 of the Approved Flight Manual for Models 'E' & 'G'). At
that speed, anytime you move the yoke back gently the energy of the
"excess speed" is converted into altitude and the plane's altitude
increases even as the forward speed decreases. Your speed for "Best
Angle of Climb" is even slower at full throttle. This is simply NOT a
speed range where you are tempting fate so long as you understand how
to trade speed for altitude and altitude for speed. This is a
fundamental skill all should practice, but If you are more comfortable
flying the approach at 80 mph, do so. The speed of the approach is
relatively unrelated to the speed at which touchdown takes place.
Most find it easier to establish a "stabilized approach" (constant
airspeed and engine rpm while maintaining a relatively constant rate of
descent with the yoke) until just before touchdown. When you cross the
runway threshold at 5-10' up reduce power and SLOWLY move the yoke back
only as fast as does NOT make the bird climb. The idea is to slowly
increase drag with higher and higher angle of attack holding the plane
one foot off the pavement and when ALL the "excess speed" is thus
scrubbed off the plane will gently sink to a very smooth landing.
Unfortunately you may be using 4000'+ of runway to do it.
Now do this again, establishing the one-foot-off slow flight.
Simultaneously close the throttle and move the yoke back to keep the
plane "balanced" at that one foot off. Once THAT coordination is
worked out, reduce engine rpm on final (if necessary) to cross the
"fence" at 70 mph. This should make it possible, with practice, to
land and make most second turnoffs WITHOUT BRAKES!
Minimum speed at the moment of touchdown is desirable because (1) the
plane can't lift off the runway again without power, (2) the wear on
the tires (the "chirp" at touchdown) is less because they have to "spin
up" only to the lower speed, and (3) brake puck and disk wear is
reduced so much that once the technique becomes "standard operating
procedure" for you there will likely be the need to land fast and hot
about once a month in order that the puck remove the accumulated rust
from disuse.
Operating a properly rigged Ercoupe in this manner is "stall proof"
except in high, gusty crosswinds. For high, gusty crosswinds, add 5-10
mph to your approach speed, but chop the power over the runway
threshhold at 5-10' up and do everything in the preceding paragraph
exactly the same from that point on. Having extra speed at or after
touchdown is a PROBLEM, not "insurance". Should a gust suddenly lift
the plane off the runway, immediate throttle restores lift to the wings
and returns to the pilot the option of go-around or a smooth landing
(remaining runway permitting).
Until this level of proficiency is developed (and more than a few that
will "instruct" in a coupe don't have it to pass on), your are not
master of the Ercoupe. Until you are master there is risk. Maximum
safety depends on owners or operators reducing that risk to zero with
appropriate priority.
Your metal wings reduce your useful load, but they have no meaningful
effect whatsoever on your approach speed or minimum (touchdown) speed.
Hope this helps.
William R. Bayne
.____|-(o)-|____.
(Copyright 2010)
On Mar 14, 2010, at 22:43, Jerry Ward wrote:
You guys all keep talking about landing your coupe at such slow speeds
- I have a metal wing G-model and I have trouble getting it to land
under 75mph. I sure am jealous of all of you that can land slow. If
I were to try that I would break my landing gear off. It starts to
fall out of the sky about 72mph.. And I do mean fall fast. Jerry in
the Great Northwest.
----- Original Message -----
From: Ed Burkhead
To: ety
Sent: Sunday, March 14, 2010 7:45 PM
Subject: FW: [ercoupe-tech] Kim's Ercoupe
Maybe this is more readable:
As I said a couple of days ago, this gave these results:
13˚ up travel 48-52 mph landing speed
415-C and 415-CD
9˚ up travel 55-60 mph landing speed
415-D and on earlier models
with 9˚ elevator limitation due
to using the 1320 pound STC
20˚ up travel 48-52 mph landing speed
415-E and all later models AND
earlier models with split elevator
installed via STC or field approval
on a form 337
