Who does flight plans?

T o d d P a t t i s t wrote:

AOA is a scalar.

Actually, if the wing is reasonably designed, the AOA *is* a vector. It
changes along the wing, usually being smaller at the wing tip and bigger
at the wing root. Hence, it cannot be described by a single scalar, but
rather by a -you guessed it- vector. On the most modern wings (e.g.
Antares), this vector is even infinite-dimensional.

I'm aware that this was not what Neil meant when he was talking of AOA
being a vector.

Stefan

T o d d P a t t i s t wrote:

the span into that function and evaluate it. It's never a
vector.

Two ways to describe the same thing. (Reminds me on Newton and
Bernoulli... shall we start? :-) But I agree that the function picture
is more natural.

As a side note, this is getting kind of tangential to
aviation.

Not too surprizing in this group.

Stefan

Neil Gould wrote:

If what you think is true, then it is possible to determine the AOA
when the aircraft is parked. Do so, and I'll revise my thinking. The
wonderful thing about this level of mathematics is that it is not
ambiguous. If any usage results in a violation of the definition,
then the usage is wrong, period.

Sorry if I was harsh. The point is, usually one coming seeking knowledge is not
quite so sure of himself. You might do better to ask questions rather than
asserting that you know everything, that you are right, and anyone claiming
otherwise is "wrong, period". If you rely on a brief dictionary definition of
terms, it is likely you are missing a lot of nuance and detail.

Anyway, a high-school or undergraduate mathematics text is a better source of
knowledge about scalar and vector mathematics than either a dictionary or this
group. I recommend you get one and read and understand it.

Dave
--really-- gone from this thread this time.

Recently, Dave Butler posted:

Neil Gould wrote:

If what you think is true, then it is possible to determine the AOA
when the aircraft is parked. Do so, and I'll revise my thinking.
The wonderful thing about this level of mathematics is that it is
not ambiguous. If any usage results in a violation of the
definition, then the usage is wrong, period.

Sorry if I was harsh. The point is, usually one coming seeking
knowledge is not quite so sure of himself. You might do better to ask
questions rather than asserting that you know everything, that you
are right, and anyone claiming otherwise is "wrong, period". If you
rely on a brief dictionary definition of terms, it is likely you are
missing a lot of nuance and detail.

Your guidance is appreciated, Dave. However, I think you may have an
impression of me and "how we got here" that doesn't reflect my
"self-assurance". I am not claiming to "know everything", or even nearly
so. I do ask questions, such as the one that I've repeatedly asked, above,
and so far have gotten only replies that I'm wrong and everyone else has
the "right answer period". As well, a lot of my "attitude problem" stems
from the claims that were erroneously attributed to me, and the subsequent
responses from those that thought those attributions were true, or at
least didn't acknowledge that they weren't.

Frankly, I think we've all been dancing around this, and I suspect it's
gone way beyond its importance with regard to how we use AOA in every-day
aviation. ;-)

Anyway, a high-school or undergraduate mathematics text is a better
source of knowledge about scalar and vector mathematics than either a
dictionary or this group. I recommend you get one and read and
understand it.

(chuckle) Unfortunately, I got rid of those many decades ago. However, the
few calculus, geometry, and logic texts that I still have from my time in
engineering school (also many decades ago, so I'm not claiming any special
priveledge on the basis of that experience) so far don't refute what I've
presented: a vector with a magnitude of zero is legit; a scalar with a
directional component is not.

I can envision an argument that hasn't been presented that would establish
AOA as a scalar, and it relates to the question the AOA of an aircraft
while parked. I'm searching for a valid example of it (off-line, btw),
but, so far, I've come up dry. If I do find one that supports the argument
I envision, I'll present it as a follow-up refuting my own assertion,
along with an apology to those I suggested were "wrong". Not that they're
holding their breath, since they just think I'm just "wrong", anyway!
;-)

Regards,

Neil

Stated another way, AOA doesn't exist *without* a directional component.

No. AOL doesn't exist without a =component= with a directional
component. Not the same.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain."
(chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

it is valid for a vector to have a magnitude of zero.

Correct.

It is NOT
valid for a scalar to have a directional component

Correct.

and it is meaningless
to have an AOA with no directional component and magnitude

Incorrect. I can give you many examples of such AOAs. Can you give me
an example of an AOA that =itself= has a direction and magnitude? (Not
that it's derived from things that have direction and magnitude, but
that it, =itself= has such)

The two aspects of the AOA is referenced to the wing chord and relative
wind, not the fuselage.

The two aspects of the AOA are referenced to each other. I refereneced
them to the same other thing (fuselage) and then derived their relation
to each other.

I'd say that it is often "OK" to PRESUME the directional components and
IGNORE their value if they are unimportant to usages where only the angle
is needed.

It is not OK to presume anything in math. Things are what they are
defined to be.

You might be thinking of "unit vectors" in which case a magnitude of one
is used, but they are defined that way. Or you might be thinking of the
algebraic sign (which is part of a scalar quantity).

We're not talking about generic "angles", but an "Angle Of Attack"

An angle of attack =is= an angle. All angles are scalars. Therefore,
an angle of attack is a scalar. Which part of this do you disagree with?

i.e.,
a specific usage which is defined by and inseparable from the components
of motion (aka relative wind).

Defined by, yes. Inseperable from, no.

The price to earnings ratio (PE) of a stock is =defined by= the dollar
price of a stock, and the dollar earnings of the company divided by the
number of shares outstanding. Without those components, you don't have
a PE ratio. But the PE is a pure number. It is not a dollar amount.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain."
(chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

Actually, if the wing is reasonably designed, the AOA *is* a vector. It changes along the wing, usually being smaller at the wing tip and bigger at the wing root. Hence, it cannot be described by a single scalar, but rather by a

That's not what a vector is.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain."
(chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

George Patterson wrote:

Matt Whiting wrote:


I do greaser full-stall landings just as I was taught.


I have never seen anyone do a greaser full-stall landing; the two are
contradictory. If you have enough speed to grease it on, you're not even
close to a stall. Most people rarely do full-stall landings, and nobody
I know teaches students to stall the plane in. You touch down with some
flying speed.

Not at all. You come in and level out an inch or less above the runway
and then bleed off speed until you stall and settle onto the runway. It
is very smooth when done correctly.

Maybe nobody you know does, but R.C. Johnston at N38 taught his students
this way for probably 50 years.

Matt

"Matt Whiting" wrote in message
...
George Patterson wrote:

Matt Whiting wrote:


I do greaser full-stall landings just as I was taught.


I have never seen anyone do a greaser full-stall landing; the two are
contradictory. If you have enough speed to grease it on, you're not even
close to a stall. Most people rarely do full-stall landings, and nobody
I know teaches students to stall the plane in. You touch down with some
flying speed.

Not at all. You come in and level out an inch or less above the runway
and then bleed off speed until you stall and settle onto the runway. It
is very smooth when done correctly.

Maybe nobody you know does, but R.C. Johnston at N38 taught his students
this way for probably 50 years.

Matt

That's not a full stall landing. That's flying it on.

"Matt Whiting" wrote in message
...
George Patterson wrote:
I have never seen anyone do a greaser full-stall landing; the two are
contradictory. If you have enough speed to grease it on, you're not even
close to a stall. Most people rarely do full-stall landings, and nobody
I know teaches students to stall the plane in. You touch down with some
flying speed.

Not at all. You come in and level out an inch or less above the runway
and then bleed off speed until you stall and settle onto the runway. It
is very smooth when done correctly.

Maybe nobody you know does, but R.C. Johnston at N38 taught his students
this way for probably 50 years.

An inch or two? Chuck Yeager should be so good.