On 2010-08-18 6:47 PM, [email protected] wrote:
I've heard this over and over but if that little cable isn't on the
nose gear and your landing speed is a little hot, you will hit the
nose gear first, because the nose gear hangs down lower, and enter to
what many is called a JC maneuver, as in "J-----s C------t!!!!!!!!!!!
It is also called a PIO, or pilot induced oscillation and is the
primary reason a lot of Ercoupes have a bent firewall. I say keep the
cable and save the Ercoupe.
Bart
Bart,
(long, but useful I think - in four parts)
I've been around Coupes - and paying close attention - for most of 32
years, now and I can say I've never heard that one.
Please let me elaborate.
If you land hot (or slow), even in a crab with no snubber cable and the
nose gear hanging way down AS DESIGNED, then the nose gear will touch
soon after the mains and before significant weight is on the mains.
No huhu!
The nose gear can turn.
That is, unless you are disregarding the Ercoupe piloting instructions
which say you should hold the yoke lightly so the nose wheel is free to
turn.
So, the side load on the nose wheel is instantly relieved. The mains,
being laterally fixed, cannot relieve their side loads except by turning
the whole plane, AS DESIGNED.
It works. I've done it over and over including in direct crosswinds up
to 30 mph with never more than a 10 foot diversion from the runway
center line.
If and only if you hold the yoke in a tight grip and don't allow it to
jerk, then you can get a significant diversion from the runway center line.
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PIO, Pilot Induced Oscillation, is a term that can probably be applied
to several flying situations. The one that applies to landings is when
the pilot fails to make a smooth flare from the final glide to the
virtually horizontal flight just before touchdown. Sometimes pilots,
especially new or out-of-practice pilots will pull too hard on the yoke,
flare nose high and getting slower, push too hard to get the nose down
and find themselves heading nose down toward the runway and . . .
Sometimes they'll hit nose down after a single oscillation, sometimes
they'll keep it in the air through a few oscillations but if they don't
get it under control they may well hit the ground nose down, folding
under the nose gear and bending the firewall.
This has nothing to do with the snubber cable - except, if the snubber
cable is present then the nose gear has much less of its designed shock
absorption capability so an impact that might have been saved by the
shock absorber could cause sever damage because the snubber cable is
present.
___________________________________
Dave Winters makes an interesting point and I agree with Bill - I hadn't
thought of the snubber cable that way, as an advantage on a rudder pedal
equipped Coupe. I have flown hundreds of hours in a rudder pedal Coupe
with a snubber cable and I did do a LOT of side-slip, wing-low
touchdowns, upwind main first, then downwind main then nose. It may
well be that the snubber cable helped make that u-main, d-main, nose
sequence work out so well. Well explained, Dave!
(Side note: At crosswind speeds above 15 mph crosswind component, I
leveled the wings and landed like a 2-control Coupe. There was enough
rudder effectiveness to exactly counter a 15 mph direct crosswind but
not more. However, landing in a crab with wings level, the three
control Coupe handles strong crosswinds just a nicely as does a
2-control Coupe.
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The real J_____ C_____ maneuver with a Coupe is when you have a drooping
tail. In that case, the wings can be at enough of a positive angle of
attack on the ground that a strong crosswind can lift a wing after the
landing. It can be so bad that the pilot may think he/she will touch
the downwind wingtip (but that's extremely unlikely to happen due to the
dihedral). And, wheelbarrowing along on the nose and one main with a
wing reaching for the sky is highly scary and likely to cause diversion
off the runway into any obstacle within a hundred feet or more.
Thus, it is VERY valuable to have your main landing gear maintenance up
to date and have your on-the-ground attitude very nearly level as
measured by the datum, the windowsill.
When the Coupe is level in pitch on the ground, the wings have nearly
zero angle of attack so they have virtually no lift and on the ground
behavior is proper even with strong crosswinds.
Ed
