Ed,
Thanks for that information ...... and I'll take your word for it!
Dan
On Jan 14, 2009, at 1:33 PM, Ed Burkhead wrote:
Kevin wrote:
> Yes the Ercoupe has a limited elevator and therefor
> limited stall but it is more that it can't be cross controlled in
> that stall that makes it "characteristically" incapable of spinning.
> In fact note 2 in the TC list the following placards when the
peddles
> are installed "This aircraft characteristically incapable of
> spinning," or "Intentional spins prohibited."
Kevin,
Your thoughts are logical, but, I think I'll disagree with your
statement
that the inability to be cross controlled in the stall is what
makes the
Coupes "characteristically incapable of spinning."
The fact that Note 2 of Aircraft Specification No. A-718 still
permits the
placard saying "This aircraft characteristically incapable of
spinning"
gives me one indication that the inability to spin is maintained.
I think that even a two control Coupe can be forced to temporarily
enter a
spin, i.e. with a hammer-head stall but the Coupe won't stay in the
spin no
matter what you do with the controls. I think this is also true of
three-control Coupes.
Flying a THREE-control Ercoupe, I did stall testing with the
controls FULLY
CROSSED. I found that, with the controls fully crossed, the Coupe
still did
not enter a spin. This was true even with the more aggressive
stalls at
higher and higher power (I had a straight elevator) pushing down
the tail
via the slipstream.
Yes, the ride got wild in the high power (C-85), fully cross
controlled
stalls but it didn't drop off into a spin.
On my highest power, fully cross controlled stall test, the left
wing did
drop and the plane "fell" into a nearly level, slow left turn in an
almost
level attitude. As I was already fully cross controlled, with full
right
aileron and full left rudder, that was as bad as it could get.
Slightly
relaxing the cross control on either the rudder or elevator let me
stop the
slow left turn.
Redusing the yoke back pressure, even slightly, also restored full
controllability.
Admittedly, I chickened out after the full power minus about 100
rpm level
and did not do an absolutely full power, fully cross controlled stall.
(And, I was airsick by then.) Note, though, that with my extreme climb
prop, I think my 100 rpm below max behavior was similar to what
most Coupes
would get with full power.
Testing was done at high altitude, naturally.
So, I *think* that the characteristic inability to spin is
maintained even
in the three control Coupes.
My testing is INSUFFICIENT to prove it for all Coupes. Records from
the
extensive testing done during Ercoupe certification would be needed
to make
that proof.
So, it's just my humble opinion. And, even if I'm right about a
properly
rigged and flown Ercoupe, due to rigging errors, an aft CG, or other
specifics of your plane, my observation may not apply to your plane.
Ed
