A letter I sent to the Wings Channel

Garrett wrote:

Good Letter, my complaint on DW channel, and alot of airshows, hobby shops,
etc..etc..is simple...

Why the obsession with Military stuff? To me it is boring.....stuff I
don't relate to, and not about flying, military planes are for
fighting......the official name of the F-15 on the data plate on the
aircraft and in McD drawings is 'Weapons Platform'....not aircraft...

Give me GA and Transport in equal time with the military stuff....


I agree with this. Am I the only person who would like to see them do
more shows on types of aircraft you don't often see, like commuter
turboprops, charters, etc.

"Big John" wrote in message
...
Darrell

Had to stop one night to refuel at Bunker Hill. Was standing outside
of ops and heard this big noise.

Saw a big fire light up the sky and finally realized it was a B-58
taking off in burner.

More noise and fire from A/B's than I had ever seen or heard.
Couldn't tell if it was a normal take off or burning up G
They got airborne after a long run and shut down the burners and
climbed out on the mission.

Got in our refueled fighter and went home. Glad I wasn't stationed on
base with noise of '58 take-offs. (

Big John

One evening a couple years ago, inside the house, I heard a rumble, and went
outside to see what was going on. It continued for about a minute, then
suddenly quit.

A few days later, I found out what the noise was. I live in the foothills,
and a B-1-B had been doing low level river following, then kicked the burner
in and went straight up.

That happened about 5 or 6 miles away. Impressive!

Jim in NC

----clip----

"Tim Bengtson" wrote in message
The stall, by definition,
starts where the coefficient of lift begins to decrease with increasing
angle of attack. It's simple; why not say it correctly and be done with
it?

Umm, because 90% of your listening audience would not know what the hell you
just said? As a primary student, I didn't give a damn about lift
coefficients and wouldn't know an angle of attack from an attack onn my
angle. All I needed to know what that at a certain speed, the plane will
stop flying and fall from the sky.

If you want to know more than what's presented in the sho, buy the King
DVDs. For the rest of the audience, the material is presented clear enough.

--
Jim Fisher

"Jim Fisher" wrote:

Umm, because 90% of your listening audience would not know what the hell you
just said? As a primary student, I didn't give a damn about lift
coefficients and wouldn't know an angle of attack from an attack onn my
angle.

If you don't have even a basic understanding of how a wing
works, you are a prime candidate for any number of fatal
accident scenarios from departure stalls at high altitude
airports to spins.

All I needed to know what that at a certain speed, the plane will
stop flying and fall from the sky.

The wing will stall at any attitude and any airspeed.
Knowing the "stall speed" is not enough. If you don't like
the proposed explanation, it can be as simple as:

As the front edge of the wing is tilted up, the wing
produces more lift up to a limit called the stall angle. As
the front edge is tilted up more than the stall angle, the
lift begins to decrease instead of increase.
Todd Pattist
(Remove DONTSPAMME from address to email reply.)
___
Make a commitment to learn something from every flight.
Share what you learn.

Gary L. Drescher wrote:

[snip]

The problem is that there's no such speed. Say you're flying a plane whose
Vs is 50 knots. Under a range of ordinary circumstances, the plane's
flaps-up stall speed could be as low as 45 knots or as high as 75 knots. A
plane stalls at a specific angle of attack, not at a specific airspeed. A
primary student who expects the contrary, or who does not understand how
airspeed relates to angle of attack under different circumstances, has no
good way to anticipate when the plane will stall.

Even when a primary student get their hands around the notion that the
wing can stall at any airspeed, they tend to equate angle of attack with
pitch attitude. They seem to grok "relative wind" on the ground but the
concept seems to skitter out the storm window in flight.

I dunno. With a primary student there's (initially at least) a thin
line between providing enough information and providing too much. Much
of what we do as aviators involves controlling AOA, but if we start
talking about AOA too early we risk the possibility that some people
will overload and bail; if we put it off for too long we end up with
people who never quite understand pitch/power, chase the elevator trim
all over the sky and describe sine waves on the glide slope.

It's a pity that all of those nifty AOA indicators are restricted to the
experimental fleet. Gluing them onto the wings of the 150s, 172s and
PA24s down at the flight school would go a long way toward demystifying
this stuff for people.

--
Chris Kennedy

http://www.mainecoon.com
PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97

"Chris Kennedy" wrote in message
...
Even when a primary student get their hands around the notion that the
wing can stall at any airspeed, they tend to equate angle of attack with
pitch attitude. They seem to grok "relative wind" on the ground but the
concept seems to skitter out the storm window in flight.

Part of the problem may be that the usual AoA diagrams all show the relative
wind coming in horizontally. If that were always the case, then pitch and
AoA would indeed be interchangeable. I bet it would help to show a student
three distinct AoA diagrams, for climb, cruise, and descent.

It's a pity that all of those nifty AOA indicators are restricted to the
experimental fleet. Gluing them onto the wings of the 150s, 172s and
PA24s down at the flight school would go a long way toward demystifying
this stuff for people.

Yup, another part of the problem is the invisibility of AoA, at least with
regard to a static picture. Dynamically, though, a pilot can see the AoA by
finding the aim point and noticing its vertical position in the window. I'd
guess that learning to perceive the AoA that way makes it far more intuitive
than using an AoA indicator, which just reports a disembodied number (though
I've never used one, so I can't be sure). But isn't the yoke position a
pretty good AoA indicator?

--Gary

Gary L. Drescher wrote:

[snip]

Yup, another part of the problem is the invisibility of AoA, at least with
regard to a static picture. Dynamically, though, a pilot can see the AoA by
finding the aim point and noticing its vertical position in the window. I'd
guess that learning to perceive the AoA that way makes it far more intuitive
than using an AoA indicator, which just reports a disembodied number (though
I've never used one, so I can't be sure).

Yep, n a steady-state environment that's probably true. The problem is
that environmental factors (like a significant updraft component) can
cause the out-the-window picture for AoA to change. While a number is
just a number, it's trivial to repeatedly nail the same AoA independent
of conditions by nailing the same number. The other (possible)
advantage of the number is that it tells you where you are relative to
lift reserve, but then that's something that most light aircraft will
let you feel in the yoke as you get to the limits.

I suppose the way I look at it is that an aviator who understands AoA
and is familiar with their aircraft needs an AoA indicator about as much
as they need a stall warning system. For those who are less that
intimately familiar it provides a tool that makes flying at high AoA
easier and safer and would graphically dispel in the mind of the primary
student the notion that AoA is a function of where the nose is pointing
relative to the ground.

But isn't the yoke position a pretty good AoA indicator?

Indirectly. It's a good indicator of what is being commanded; combined
with what the aircraft is doing you can infer whether you're skating
toward an excessive AoA. It's a bit more problematic in, say, the
mountains on a windy, hot afternoon, where AoA can change wildly while
the yoke is held in a constant position (and Va is your new best
friend). There are other -er- more degenerate places where the
relationship between stick and AoA are problematic, like an accelerated
or flat spin, but under those conditions I seriously doubt I'd be
looking at an AoA indicator

--
Chris Kennedy

http://www.mainecoon.com
PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97

"Jim Fisher" wrote in message ...
I didn't give a damn about lift
coefficients and wouldn't know an angle of attack from an attack onn my
angle. All I needed to know what that at a certain speed, the plane will
stop flying and fall from the sky.

Yikes! I think an explanation of angle of attack and stressing the
the plane can stall at any speed is pretty damned important
information for the student pilot. If you think the plane will only
stall at a certain speed, you're setting yourself up for a stall/spin
on a botched turn to final (not an uncommon occurance when you're a
student).

I agree that the show doesn't need to delve into the minutae of
aerodynamics, but I don't think AOA qualifies as minutae.

John Galban=====N4BQ (PA28-180)

On Tue, 29 Jul 2003 07:46:34 -0700, Tim Bengtson
wrote:

Steve House wrote:

Well certainly textbooks can be in error. But where are the odds of
accuracy better, several independent pieces of instructional material vetted
through virtually every ground school and CFI in the country or a couple of
lone voices on the internet? What is your source
for the contrary view?

Steve, the problem is that all those textbooks were written by pilots.
Remember, the reason they became pilots in the first place is that they
couldn't do math well enough to become engineers :-) :-) Anyway, here
is a good reference that talks about flying a stalled wing:

http://www.av8n.com/how/htm/vdamp.html#sec-beyond-stall

If you get a chance, read the whole online book. It's not dumbed-down
like the typical pilot texts.

My experience disagrees with a couple of his points, but nothing major
and quite possibly I'm misinterpreting what I've seen.

If I'm in level flight and extend the flaps 10 or 15 degrees and
maintain the speed my plane *will* climb. To me that says the wing
has more lift when I extend the flaps 10 or 15 degrees than with no
flaps.

The other is that all bits of the wing contribute equally to the lift.
I'm probably missing something, but I think different areas of the
wing produce different amounts of lift per square inch, or square
foot. Particularly where the airfoil changes shape between the root
and the tip as opposed to a constant cord wing like the old Hershey
bar wing on the Cherokees.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

Tim

On Fri, 08 Aug 2003 01:48:20 GMT, Roger Halstead
wrote:

If I'm in level flight and extend the flaps 10 or 15 degrees and
maintain the speed my plane *will* climb. To me that says the wing
has more lift when I extend the flaps 10 or 15 degrees than with no
flaps.

Ack. Pth. In equilibrium, lift == weight. This is a first-order
approximation, of course, but when you're climbing or descending, lift
is still weight. You climb because of excess energy, not because of
excess lift. If you lower the flaps, to maintain the same airspeed
without increasing the power, you will have to lower the nose. Flaps
increase drag, and if you don't add power the lost energy comes from
altitude.

There is a transient effect: if you maintain the same angle of attack
as you lower the flaps, the airplane will probably balloon initially,
until your airspeed bleeds off, then you will begin to descend at a
lower airspeed. Your airspeed at the same angle of attack needs to be
lower because lift is a function of the coeficient of lift (which you
increase by lowering the flaps) and airspeed (which you reduce to
maintain the constant lift).

HTH,

Morris