AoA keep it going!

Bill Daniels wrote:

20% of males suffer some degree of color blindness. A multi-color LED would
be difficult for them to interpret.

In any event, a 3-color LED is just 3 different LED's in the same case so
stacking 3 LED's in a vertical column is neither more nor less complicated.

That doesn't apply to them all.

There is a three lead version which is just a red and a green LED in one
package but there's also a two lead type where the applied voltage
controls the colour.

I remember experimenting with one of these as the output of an LM 358
op-amp and was able to get any colour across the range red to green from
it by adjusting the input voltage. I was thinking of the latter type and
that it would be easier to mount on the glare shield because it only
needs a 3mm hole or a very small enclosure.

I take you point about colour blindness though, but that would apply to
any tri-LED arrangement unless it was big enough for it to be obvious
just which LED was on.

I'd suggest that there are better displays to use: a 10 segment bar
graph type indicator should be best, arranged so that the segments
turned on from the bottom. The more segments that are on, the higher the
AOA. The option of making it flash as the AOA gets close to the stall
would be a nice feature. It could use LED or LCD technology. Best of
all, this type of display is small, so in many cases it could be placed
alongside the ASI without causing a panel rebuild. If the vertical
display was less than 6mm wide I could even get it into my Libelle's
panel between the T&B and the ASI, which is top center, just where I
like it.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

kirk.stant wrote:
In my
experience, light power planes not really more susceptible to approach
stalls than gliders,

By approach stalls, so you mean stall on final approach? I thought that
was a rare accident gliders, and that most stalls during landing
occurred in the turns.

but there are more distractions - including that
noisy thing in the front just waiting to quit! Yet they mandate stall
warnings.

I don't know the reason that it's mandated, but that noisy thing up
front does change things significantly. For example, under power in my
motorglider, the nose attitude at 50 knots can vary from below the
horizon to above the horizon; the attitude while gliding at 50 knots is
constant and consistent. So, I suggest determining a safe AOA is harder
in powered aircraft, and this makes a stall warning more valuable.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Kirk,

Could you summarize for me _how_ you used the AOA indicator in those
aircraft, which aircraft and under what conditions ?

I am curious to the actual use(s).

Thanks
Todd Smith
3S

Sure. I used AOA in T-38s (a little - not much flight time in those)
and in F-4s (about 2000 hours in those). In my current job, I fly a
variety of F-15 simulators (the real thing, not PC games) and use AOA
all the time. Have also a few flight in F-16s and a lot of time in
F-16 simulators, which use AOA in the approach and landing
configuration.

In a nutshell, AOA is used anytime optimum performance is required
from the wing - be it turning, flying an approach, flying for max
range, recovering from a dive, etc. Since fighters can vary weight a
lot due to fuel burn and store (weapons) configuration, it's
impractical to try to use airspeed other than as a general guide to
your energy state - your airspeed tells you how much instantaneous
energy you have to maneuver, then you fly at the AOA that matches the
type of turn you want - less AOA is conserves energy, more AOA turns
faster, etc. If you are flying for max range or max endurance, again
there is a recommended AOA to fly at - it will stay the same while
the actual airspeed changes based on gross weight, configuration, and
altitude. Finally, in the pattern, you figure out the approximate
airspeed and AOA based on fuel and stores remaining, then crosscheck
the two - if they agree, it's easier to fly AOA on most jets (F-4
especially, F-15 less so).

Now, compared to gliders, these are all extremely low aspect ratio,
and that will exaggerate AOA effects. But the aerodynamic priciples
are the same.

Finally, someone questioned about whether it's better to thermal
efficiently or in the best part of the themal. The answer, IMHO, is
that you should strive to do both. Right now we have wonderful
instruments to help us find the best lift. But we still use a crude
instrument to fly efficiently. Well, actually, most people probably
thermal more by feel and attitude than by staring at the airspeed
indicator.

End of war story.

Cheers,

Kirk

On Dec 20, 5:17 pm, "kirk.stant" wrote:
Sure. I used AOA in T-38s (a little - not much flight time in those)
and in F-4s (about 2000 hours in those). In my current job, I fly a
variety of F-15 simulators (the real thing, not PC games) and use AOA
all the time. Have also a few flight in F-16s and a lot of time in
F-16 simulators, which use AOA in the approach and landing
configuration.

Excellent post Kirk. I was about to ask if anyone had fighter-jet
experience and you do! I was going to ask as I recall that in an
accident report on a fatal stall/spin after a missed approach to a
carrier by a F-14 one of the key aspects had been the crew's
monitoring of the AoA. IIRC - though I'm not sure I do - the rear-seat
crew member actually calls out the AoA to the front-seat pilot, who
has too many tasks to do to also include checking the AoA in their
scan.

Finally, someone questioned about whether it's better to thermal
efficiently or in the best part of the themal. The answer, IMHO, is
that you should strive to do both. Right now we have wonderful
instruments to help us find the best lift. But we still use a crude
instrument to fly efficiently. Well, actually, most people probably
thermal more by feel and attitude than by staring at the airspeed
indicator.

I was thinking the same thing. I have often wondered about the best
speed to fly at any given moment when thermalling, including using
that online calculator thing to get some guidelines which were a fair
bit faster than I thought they would be. As you say, it's odd that we
have great varios, but nothing very good to get the most from our
wings.

I'd be interested in an AoA indicator for performance reasons, but not
so much for safety, where I personally think a good safety margin on
the ASI does the job (plus not leaving it too late to have to pick a
small field to land in, so ground-roll distance is such a factor).


Dan

On Dec 20, 12:17 pm, "kirk.stant" wrote:
Kirk,

Could you summarize for me _how_ you used the AOA indicator in those
aircraft, which aircraft and under what conditions ?

I am curious to the actual use(s).

Thanks
Todd Smith
3S

Sure. I used AOA in T-38s (a little - not much flight time in those)
and in F-4s (about 2000 hours in those). In my current job, I fly a
variety of F-15 simulators (the real thing, not PC games) and use AOA
all the time. Have also a few flight in F-16s and a lot of time in
F-16 simulators, which use AOA in the approach and landing
configuration.

In a nutshell, AOA is used anytime optimum performance is required
from the wing - be it turning, flying an approach, flying for max
range, recovering from a dive, etc. Since fighters can vary weight a
lot due to fuel burn and store (weapons) configuration, it's
impractical to try to use airspeed other than as a general guide to
your energy state - your airspeed tells you how much instantaneous
energy you have to maneuver, then you fly at the AOA that matches the
type of turn you want - less AOA is conserves energy, more AOA turns
faster, etc. If you are flying for max range or max endurance, again
there is a recommended AOA to fly at - it will stay the same while
the actual airspeed changes based on gross weight, configuration, and
altitude. Finally, in the pattern, you figure out the approximate
airspeed and AOA based on fuel and stores remaining, then crosscheck
the two - if they agree, it's easier to fly AOA on most jets (F-4
especially, F-15 less so).

Now, compared to gliders, these are all extremely low aspect ratio,
and that will exaggerate AOA effects. But the aerodynamic priciples
are the same.

Finally, someone questioned about whether it's better to thermal
efficiently or in the best part of the themal. The answer, IMHO, is
that you should strive to do both. Right now we have wonderful
instruments to help us find the best lift. But we still use a crude
instrument to fly efficiently. Well, actually, most people probably
thermal more by feel and attitude than by staring at the airspeed
indicator.

End of war story.

Cheers,

Kirk

Kirk,

I understand (in theory) how you would fly at an optimal AOA, but I
was hoping for a more procedural idea on how to use an AOA indicator.
Do you use it like a "control instrument", like an attitude indicator,
or a "perfomance instrument", like the airspeed ?

Todd
3S

PS. It sounds like you work at some training or simulation
development group for Boeing, St Louis ?

On Dec 19, 9:48 pm, Ian wrote:
This is going to lead on to my second favourite question for
instructors: "We all fly the approach a bit faster if there is likely
to be significant wind shear. As we fly through the wind shear, should
we (a) attempt to keep the higher speed or (b) allow speed to decrease
(which is why we added a bit to start)?

What's the answer? I've thought about this myself. I tend to try to
maintain the higher speed until round-out, when I stop periodically
checking the ASI and concentrate fully on the view out.


Dan

I think this entire thread can be summed up as follows:

If you have had the opportunity to fly with an AOA for an extended period of
time ... you would like to have one in your sailplane.

If you haven't had the opportunity to fly with an AOA ... you don't seen the
need or value.

Beyond that, all this discussion is academic and I am getting tired of the
thread.

Respectfully,

Wayne
HP-14 "6F"
A-3B SkyWarrior / A-6A Intruder Bombardier who has observed 1000+ carrier
landing from the cockpit.

P.S. I would like to have an AOA in my old HP-14.
http://www.soaridaho.com/Schreder


"kirk.stant" wrote in message
...
Kirk,

Could you summarize for me _how_ you used the AOA indicator in those
aircraft, which aircraft and under what conditions ?

I am curious to the actual use(s).

Thanks
Todd Smith
3S

Sure. I used AOA in T-38s (a little - not much flight time in those)
and in F-4s (about 2000 hours in those). In my current job, I fly a
variety of F-15 simulators (the real thing, not PC games) and use AOA
all the time. Have also a few flight in F-16s and a lot of time in
F-16 simulators, which use AOA in the approach and landing
configuration.

In a nutshell, AOA is used anytime optimum performance is required
from the wing - be it turning, flying an approach, flying for max
range, recovering from a dive, etc. Since fighters can vary weight a
lot due to fuel burn and store (weapons) configuration, it's
impractical to try to use airspeed other than as a general guide to
your energy state - your airspeed tells you how much instantaneous
energy you have to maneuver, then you fly at the AOA that matches the
type of turn you want - less AOA is conserves energy, more AOA turns
faster, etc. If you are flying for max range or max endurance, again
there is a recommended AOA to fly at - it will stay the same while
the actual airspeed changes based on gross weight, configuration, and
altitude. Finally, in the pattern, you figure out the approximate
airspeed and AOA based on fuel and stores remaining, then crosscheck
the two - if they agree, it's easier to fly AOA on most jets (F-4
especially, F-15 less so).

Now, compared to gliders, these are all extremely low aspect ratio,
and that will exaggerate AOA effects. But the aerodynamic priciples
are the same.

Finally, someone questioned about whether it's better to thermal
efficiently or in the best part of the themal. The answer, IMHO, is
that you should strive to do both. Right now we have wonderful
instruments to help us find the best lift. But we still use a crude
instrument to fly efficiently. Well, actually, most people probably
thermal more by feel and attitude than by staring at the airspeed
indicator.

End of war story.

Cheers,

Kirk

On 20 Dec, 18:18, "Wayne Paul" wrote:
I think this entire thread can be summed up as follows:

If you have had the opportunity to fly with an AOA for an extended period of
time ... you would like to have one in your sailplane.

Doesn't follow. Just because one person who has flown with an AoA
indicator would like one in his glider does not mean that every who
has would.

Ian

On 20 Dec, 17:46, Dan G wrote:
On Dec 19, 9:48 pm, Ian wrote:

This is going to lead on to my second favourite question for
instructors: "We all fly the approach a bit faster if there is likely
to be significant wind shear. As we fly through the wind shear, should
we (a) attempt to keep the higher speed or (b) allow speed to decrease
(which is why we added a bit to start)?

What's the answer?

Both, depending on who you ask. I'm in favour of not fannying about
with aircraft attitude near the ground and letting the airspeed fall
if that's what the wind shear wants it to do.

Ian

Ian wrote:
On 20 Dec, 18:18, "Wayne Paul" wrote:
I think this entire thread can be summed up as follows:

If you have had the opportunity to fly with an AOA for an extended period of
time ... you would like to have one in your sailplane.

Doesn't follow. Just because one person who has flown with an AoA
indicator would like one in his glider does not mean that every who
has would.

Ian
I haven't (had the opportunity to fly w. an AoA indicator)...but I would
(like one in my [flapped] sailplane).

That noted, I do tend to agree w. Wayne there's an awful lot of
'religious belief' (subliminal ax-grinding, etc.) being repeated in this
thread that 'en-murkens' its intrinsic value.

Regards,
Bob - instrumentational minimalist - W.


P.S. With a bow to Thread Creep (and Winter, dry laugh)...as
fascinating a topic as AoA is, and as much as it affects the aerodynamic
behavior of wings, equally fascinating (to me, anyway) is the gamut of
human responses the topic has so-far illuminated. It ranges from
well-intentioned 'educators,' to inexperienced 'strong holders of
opinion skeptically resistant to change from instrumentational
status-quo.' We all know who we are!

What's fascinating to me is: What is it about 'topics' that leads to
stark opinional divergences as: a) this 'AoA discussion' vs. b) the
almost manic avidity underlying GPS overwhelm-ment of the (previously
widely held, and,) rule-forbidden resistance to navigation aids in both
badge and contest venues? I mean, w. the PW5 and silicone-in-wax
topics, we can at least sense the underlying reasons for rabidity, but
I'm struggling in this case!

There. My one attempted contribution to Northern Hemisphere Winter ROTS
(Rabidity of Topics Syndrome).