On 2010-08-19 8:53 AM, Jerry Ward wrote:
I guess I have to respond to this one.. I am one of those people that
have been landing "Hot". I have listened to many of you Couper's that
claim you land in the low 60's or at least below 70mph. Well, I have
had my Coupe for a little over two years now and it is a metal wing
1950 G' Model and I can tell you from much experience that landing
this plane below 75 would result in major repairs. I usually touch
down at around 78 to 85mph. The plane starts to sink at about 1200 ft
per min. if you let it get slower than 75mph. And that is not what
you want when you are 20 ft off the ground. I know all of you guys
with the fabric wings can land slow - but when you add the weight of
metal it is a different story. Jerry - leaving tomorrow for Kitty
Hawk from the Great Northwest.
Jerry,
*Item one, metalized wings.* Some of those who metalized the wings just
wrapped the sheet aluminum around the wing and riveted it on. They did
NOT make it conform to the actual DESIGN AIRFOIL. The design airfoil
has a mild concavity just behind the leading edge and in front of the
spar. This greatly improves the low speed ability. If your metalized
wings do not have this concavity, they may be un-airworthy (though
repairable, I'm sure).
*Item two, airspeed indicator.* MANY airspeed indicators are in error,
some showing as much as 20 mph too high when nearing touchdown speeds.
My own airspeed was off by 15-18 mph in the landing speed range claiming
I was going 65 when my true airspeed was about 50. This was a bad thing
on my second flight when the engine stopped and I flew the approach at
70 and got no flare. Check your airspeed indicator! Here's a link with
discussion and, at the bottom, a quite easy calibration method using a GPS.
http://edburkhead.com/Ercoupe/airspeed_indicator_errors.htm
Until you can do the calibration, (and don't put it off), do this: Go
up several thousand feet and do an idle-engine minimum flying speed
test. Find out what YOUR airspeed indicator says when the yoke is all
the way back to the stop and the Coupe is burbling along with its
near-stall. Use that airspeed times 1.4 for your approach speed for now
and refine it later.
*Item three, flare.* You should never be bottoming out your flare at 20
feet no matter what the conditions. (I suspect you mean that if you
started your flare at the published airspeeds, you'd fall out and fail
to flare. That brings us back to items 1 and 2.)
If your approach speed is proper (about 1.3 to 1.4 times minimum flying
speed) you should have no trouble flaring to level flight at 3-6 feet
altitude. Holding the plane level at 3-6 feet lets excess energy bleed
off as you hold that altitude then it will gradually and smoothly sink
the last little bit giving you a nice touchdown at the slowest possible
airspeed of which the plane is capable. No excess sink and thump-down
occurs because of the ground effect. As an added benefit, the ground
effect of air squeezed under our low wings gives very nice stability to
this 3-6 foot horizontal flight even in very strong and gusty wind
conditions.
*Optional extra landing technique. *On long runways, I found that
increasing the rpm to 200-300 rpm */above idle/* (just enough I could
hear that I had changed it) while holding the nose up to just touch the
landing lights at the far end of the runway slightly decreases the sink
rate even in that 3-6 foot horizontal ground effect. The slight
increase in airflow over the tail helps push the straight-tail Coupes'
tails a hint lower resulting in slightly lower actual touchdown speed.
There's some cost in terms of extra float time and distance. This
controlled sink rate touchdown was taught to me for night flying when
you don't know your exact altitude in the flare - remember that it does
require a sufficiently long runway (perhaps an extra 200-400 feet more
than your regular minimum). The advantage is that you get a
squeak-squeak touchdown every time suitable to convince all passengers
that you are an absolute master of flying!
Ed
