Stall strips vs. Washout

Sorry about that. I'm gonna blame nasty sinus infection combined with a
mixture of meds.

My follow-up was directed at JSMorgan's comments on hershey bar wings and
stall strips:

"Constant cord (Hershey Bar) wings need no twist, or stall strips, as they
stall naturally on the inboard section"

Like I was trying to say last night, the AA-1 and Tomahawk both have hershey
bar wings and stall strips.

KB


"Morgans" wrote in message
...

"Kyle Boatright" wrote

This may be a good generalization, but I can think of at least two
exceptions. The Grumman AA-1 and the Piper Tomahawk. I've never paid
much
attention to the Grumman AA-5, but I wouldn't be surprised to see 'em
there
either.

KB

An exception to what? Surprised to see what, where? You gotta incude
more
hints, unless you want to play 20 questions! :-)
--
Jim in NC

Stall strips are used to fix a design shortcoming. No engineer
wants to design a wing that stalls sooner than absolutely necessary,
but some wings didn't behave as predicted and the stall strip was meant
to induce stall on the inboard wing areas and get the nose to drop
before the ailerons lost authority. The Tomahawk has a reputation for
some nasty stall/spin behavior, and I imagine the stall strips were
meant to alleviate it somewhat. The Bonanza has them, too. With newer
computer-generated airflow modelling it's easier to spot deficiencies
before the wing is built.

Sure you don't want the wing to stall before absolutely necessary, but
that is in effect what is done with having washout- making the inboard
section of the wing stall before it absolutely had to. They felt it
was preferable to do that so at the artificially early stall you'd
still have aileron control.

wrote:
Sure you don't want the wing to stall before absolutely necessary, but
that is in effect what is done with having washout- making the inboard
section of the wing stall before it absolutely had to. They felt it
was preferable to do that so at the artificially early stall you'd
still have aileron control.


Not exactly accurate. It more like, you know the plane is going to
stall at some point, but you'd like the pilot to know about it before it
happens. The twist lets the lift drop out slowly as the wing begins to
buffet. Before the spin happens, it is hoped that the pilot will have
awakened and lowered the nose a little.

wrote:
Sure you don't want the wing to stall before absolutely necessary, but
that is in effect what is done with having washout- making the inboard
section of the wing stall before it absolutely had to. They felt it
was preferable to do that so at the artificially early stall you'd
still have aileron control.

Yeah -- to put it another way: Putting down an aileron effectively
raises the angle of attack of the outboard part of the wing. So, if you
are near the stall, aileron movement causes the outboard part of the
up-going wing to stall, dropping that wing.

A bit of washout will cure this bad behaviour by having both wings stall
at about the same time.

Frank

They are also used to generate turbulence (buffet) to wake up the pilot.
In the case of the Tomahawk, they do so with a vengeance and a glance
back at the tail (which is doing quite a dance) will scare you s**tless!

wrote in message
oups.com...
Stall strips are used to fix a design shortcoming. No engineer
wants to design a wing that stalls sooner than absolutely necessary,
but some wings didn't behave as predicted and the stall strip was meant
to induce stall on the inboard wing areas and get the nose to drop
before the ailerons lost authority. The Tomahawk has a reputation for
some nasty stall/spin behavior, and I imagine the stall strips were
meant to alleviate it somewhat. The Bonanza has them, too. With newer
computer-generated airflow modelling it's easier to spot deficiencies
before the wing is built.

On 22 Feb 2005 08:26:41 -0800, wrote:

Stall strips are used to fix a design shortcoming. No engineer
wants to design a wing that stalls sooner than absolutely necessary,
but some wings didn't behave as predicted and the stall strip was meant
to induce stall on the inboard wing areas and get the nose to drop
before the ailerons lost authority. The Tomahawk has a reputation for
some nasty stall/spin behavior, and I imagine the stall strips were
meant to alleviate it somewhat. The Bonanza has them, too. With newer
computer-generated airflow modelling it's easier to spot deficiencies
before the wing is built.

The Bo has both stall strips and wash out, BUT in a stall it is a
"rudder only" airplane.

I see references made to the nose drop. Many aircraft can be held in
a stall without the nose falling. It can be done in the Deb/Bo and it
can be done in a Cherokee with the Hershey bar wing.

HOWEVER there is a marked difference in the way they behave in the
stall. You can hold the Cherokee in a stall and carefully make turns
with the ailerons remaining effective. To say that does not happen in
the Bo would be an understatement.

Holding the Deb/Bo in a stall is like standing on a tight rope that's
not very tight. It's a balancing act done with the rudder and the
ailerons are kept neutral. If there is a general use airplane that
enforces "don't use the ailerons in a stall", it has to be the Bo or
at least the 33s. Forget and use the ailerons and you will get a
chance to put that unusual attitude recovery practice to use.

With practice (and open cowl flaps) you can wobble around in a stall
for quite a while. In a departure stall you can hold a *relatively*
slow rate of descent at full power. Mine does not like partial power
and seems to be a bit more unruly than it is with full, or climb
power.

It is at its nastiest with gear and flaps out. Just stay ahead of the
airplane and it's very predictable even in stalls.

I was doing some checking the other day and found the Deb has a lower
wing loading than a Cherokee 180 and just about half that of a Glasair
III.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Roger" wrote

I was doing some checking the other day and found the Deb has a lower
wing loading than a Cherokee 180 and just about half that of a Glasair
III.

Roger Halstead

I'm not surprised at that, with the Glasair. Fast glass =high loading. I
am surprised at the 180. Less, but close?
--
Jim in NC

On Thu, 24 Feb 2005 22:36:20 -0500, "Morgans"
wrote:


"Roger" wrote

I was doing some checking the other day and found the Deb has a lower
wing loading than a Cherokee 180 and just about half that of a Glasair
III.

Roger Halstead

I'm not surprised at that, with the Glasair. Fast glass =high loading. I
am surprised at the 180. Less, but close?

Very close

The Deb is 16.3, and Arrow is 17 and I'm trying to remember the 180 is
slightly less than the Arrow. The G-III is just under 30. (29
something plus change)

The thing is, you can come in very steep (calculate speed for weight)
with just enough power for energy to flare, plant the mains, lower the
nose, get on the brakes, and haul back on the yoke and that sucker
will surprise you with a very short landing and extremely short roll
out.

Stall with only me, half fuel, gear down and full flaps is only 55
MPH. (That is STEEP!)
Going the other direction with that wing loading and 260HP it'll hit
pattern altitude at, or just past the end of the 3800 foot runway.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Kyle Boatright" wrote


Like I was trying to say last night, the AA-1 and Tomahawk both have
hershey
bar wings and stall strips.

KB

The AA-1 had them more to make the high speed stall more noticeable, as I
recall reading , somewhere.

The AA-1 was hot little number, for that HP, and people changing to it from
slower designs could have hardly ever have produced a real mean high speed
stall in their earlier planes, as most other designs of that HP and period
were close to 50% slower.

The stall strips were there to get the pilot's attention, earlier, before
they got into trouble.

Or so I recall reading.

Tomahawks just were nasty to handle in a stall, because of the T-tail way
out of the prop blast, and they need to stall earlier to keep elevator
control? I'm guessing about that one, just from what I have heard.
--
Jim in NC