Going for my Multiengine rating

No, and with full flaps it pull an greater aoa for the same
authority(down force). It stalls. And the nose can drop real hard. As
the stab moves into ground effect the aoa increases also.

Sorry, I was thinking of a horizontal stabilizer/elevator combo.
Still, the lift coefficient of the horizontal tail most likely doesn't
get near Clmax. I regularly make full stall landings with the Seneca
using 40 degree flaps.The tail doesn't stall. If the nose drops, it's
a physical strength issue.

But the seneca nose gears take a pounding because of the way they
are flown. It
leads to failures.

The British did a very elaborate analysis of the nose gear on the
Seneca and didn't think that was a factor. The gear is designed to
withstand vertical loads. It's front to back loads that are a
problem.

I think they had three collapses over the last 15 years and none
were due to
mis-rigging.

And how do you know? Our mechanics said the same thing, but it struck
me as a cover-your-ass sort of defense.

And it is checked every 50 hours and also they hold an stc for
putting a window in so it can be inspected through the nose baggage
area each flight.

They've had the window in for 15 years? The problem only came to
light in the past few years. Our mechanics also put in a window.

This is from "Cessna Wings for the World", by William D. Thompson,
regarding the C-177:

==================================snip========== =============
The pitch-down motion in flaps-down sideslips was a more serious
problem, however. Production test pilots became aware of a more
noticeable waviness in some of the leading-edges of the wing, and
occasionally, a 2-foot length of paint overspray that caused wing-
dropping tendencies at the stall. This had to be corrected by
applying body filler material on the leading-edge or rubbing compound
to remove the almost invisible overspray. There was also questionable
uniformity of the stabilators, giving as much as 15-mph deviations in
minimum trim speeds. On some airplanes they reworked or actually
replaced the stabilator with some improvement. This led to the
decision to incorporate slots into the stabilators' leading edges so
that they could tolerate a steeper downflow of air without stalling
the under-surface of the stabilator. This solved the problem, and a
fleetwide "Cardinal Rule" retrofit was planned at no cost to the
customer. In the meantime, a service bulletin called for a temporary
installation of a simple sheet metal plate that would limit the
maximum flap deflection to 15 degrees. We were paying the price for
these thin skins.
==================================snip========== =============

So this was more than just a stabilator stalling; it had more to do
with production problems than an inherent design problem. A tail-
stalling airplane wouldn't pass certification tests.

Oh I know. I can imagine how it strikes you, but that is it. I think
they also hold some stc for some kind of mod in there also.



Greg Esres wrote:
I think they had three collapses over the last 15 years and none
were due to
mis-rigging.

And how do you know? Our mechanics said the same thing, but it struck
me as a cover-your-ass sort of defense.

And it is checked every 50 hours and also they hold an stc for
putting a window in so it can be inspected through the nose baggage
area each flight.

They've had the window in for 15 years? The problem only came to
light in the past few years. Our mechanics also put in a window.

To borrow your phrase, it strikes me more as a cya thing because it did
get out to the market place.

Greg Esres wrote:

This is from "Cessna Wings for the World", by William D. Thompson,
regarding the C-177:

==================================snip========== =============
The pitch-down motion in flaps-down sideslips was a more serious
problem, however. Production test pilots became aware of a more
noticeable waviness in some of the leading-edges of the wing, and
occasionally, a 2-foot length of paint overspray that caused wing-
dropping tendencies at the stall. This had to be corrected by
applying body filler material on the leading-edge or rubbing compound
to remove the almost invisible overspray. There was also questionable
uniformity of the stabilators, giving as much as 15-mph deviations in
minimum trim speeds. On some airplanes they reworked or actually
replaced the stabilator with some improvement. This led to the
decision to incorporate slots into the stabilators' leading edges so
that they could tolerate a steeper downflow of air without stalling
the under-surface of the stabilator. This solved the problem, and a
fleetwide "Cardinal Rule" retrofit was planned at no cost to the
customer. In the meantime, a service bulletin called for a temporary
installation of a simple sheet metal plate that would limit the
maximum flap deflection to 15 degrees. We were paying the price for
these thin skins.
==================================snip========== =============

So this was more than just a stabilator stalling; it had more to do
with production problems than an inherent design problem. A tail-
stalling airplane wouldn't pass certification tests.

Well I have tail stalled it, twice, 18 years ago when learning. CG at
the forward limit(not close, _at_), full flaps, wing in ground effect,
stabilitor moving into it's own ground effect, and don't use nose up
trim. Thinking about your other post with the claim that some overspray
created such problems, I should also point out the aircraft had the
known icing package. Looking at the boot on the stabilator it surely
must be the culprit as it is far worse than overspray or a wavy edge. As
far as I know there is no change in a sabilator that is going to be
booted or not.

Was it the wing that stalled? Back then I was taught it was the tail.
I was also warned if carrying ice to be _very_ wary of a tail stall (no
flaps). As for the cardinal, pilots at the time told me the slots came
out because some people were managing to stall the stabilator. It must
have a very forward center of gravity, but to me that is the way it
should be to make loading easier.

I have stalled the wing in the flare and that was different. I am sure I
could try to do it again but I will pass on that. Yes I trained doing
all manner of stalls, well not all, not single engine stalls. I suspect
newer Senecas go out the door with the cg farther aft as they have
gotten very heavy compared to the III's. Thinking back to the times I
did it, I still believe it was the tail that gave out. Even though it
goes against popular thinking. But nobody would believe me if I claimed
to see a flying saucer either. It's just my personal expierience,
nothing quoted from books. And like anybodies I could be wrong, but I
lived it so that is what I thought.

But your right, it doesn't make sense, they wouldn't certify the
airplane it there was any chance of the tail ever stalling under any
possible condition. I didn't know that about certification requirements.

Thanks for your thoughtful replies and setting me straight.

John



Greg Esres wrote:

No, and with full flaps it pull an greater aoa for the same
authority(down force). It stalls. And the nose can drop real hard. As
the stab moves into ground effect the aoa increases also.

Sorry, I was thinking of a horizontal stabilizer/elevator combo.
Still, the lift coefficient of the horizontal tail most likely doesn't
get near Clmax. I regularly make full stall landings with the Seneca
using 40 degree flaps.The tail doesn't stall. If the nose drops, it's
a physical strength issue.

But the seneca nose gears take a pounding because of the way they
are flown. It
leads to failures.

The British did a very elaborate analysis of the nose gear on the
Seneca and didn't think that was a factor. The gear is designed to
withstand vertical loads. It's front to back loads that are a
problem.

The Visitor wrote

Was it the wing that stalled? Back then I was taught it was the
tail.
I was also warned if carrying ice to be _very_ wary of a tail stall
(no
flaps). As for the cardinal, pilots at the time told me the slots came
out because some people were managing to stall the stabilator. It must
have a very forward center of gravity, but to me that is the way it
should be to make loading easier.

Yes, I'm aware of the icing issue. When I first posted, I was
mentally referencing a NASA tail plane report that I had been reading.
They did extensive tests and showed that an a/c is most vulnerable at
the MAXIMUM speed for a given flap setting. Each flap setting
increases the negative AOA for a particular airspeed, due to the
downwash of the wing into the horizontal stabilizer. However, as the
a/c slows, the AOA of the horizontal stabilizer becomes less negative,
because the tail rotates down; the increased downward lift is provided
by the elevator deflection, rather than increasing the AOA. I didn't
stop to think how the report would differ if they were discussing
stabilators.

One possibility for the effect you noticed is that as the main wing
stalls, there may be a decreased downwash over the horizontal
stabilizer, which would produce a downward pitching motion.

Greg Esres wrote:

One possibility for the effect you noticed is that as the main wing
stalls,

Just that will nose it down. But it was different than the wing stalling
in ground effect.


there may be a decreased downwash over the horizontal
stabilizer, which would produce a downward pitching motion.


I can't see it in a downwash while flaring. It's pretty close to the
ground. Reduced airflow I could buy but in that situation it would still
be firm and responsive to input.

Ah well....