AOA indicator

On Thursday, April 21, 2016 at 7:57:57 AM UTC+12, Jonathan St. Cloud wrote:
Dan, I certainly agree, time in the saddle beats any gadget. However, the reason years ago the SSA sponsored a contest to develop AOA is for safety.. Many pilots just do not fly enough, or cannot make enough time to fly enough. They are on the fine edge of currency and compentancy. Maybe early season.

I am sure I will be fine without an AOA, but for the sport, I think it would be a good idea with the internal nav units we have as varios. I was under the impression that the Butterfly vario and LX90xx with horizon had all the necessary hardware, just needed software for AOA. Might save a life or two.

One thing I have learned through years of flying, sailplanes, helicopters and airplanes are that anyone can be distracted for a moment and anyone can make a mistake.



On Wednesday, April 20, 2016 at 12:33:51 PM UTC-7, wrote:
True Johnathan, there has been talk over the years about adapting AOA for the crop dusting world, as we are working with very high wing loadings and at times very high density altitude situations carrying astronomically heavy loads, but it never caught on. For our world since we fly so many hours ( last year I flew over 400 hours in 6 months in the same ship) guys just develop a feel for what their ship is doing.
Dan

How exactly do you think a computer is going to calculate AoA without an AoA measurement? Using what inputs? IAS? TAS? AUW? G loading? What else?

I don't think you can do it, at least not well enough to me more useful than pilot feel. But I'm willing to be surprised.

Read the first post of this thread to see example.

On Wednesday, April 20, 2016 at 1:19:30 PM UTC-7, Bruce Hoult wrote:

How exactly do you think a computer is going to calculate AoA without an AoA measurement? Using what inputs? IAS? TAS? AUW? G loading? What else?

I don't think you can do it, at least not well enough to me more useful than pilot feel. But I'm willing to be surprised.

I would wish for an AOA sensor as well. What I would not want is a computed AOA even though I agree that the information is already present to compute it. AOA needs to be a direct sensor (sorry, Jonathan). If you are landing to the AOA indication and it is not right you may be in serious trouble. A computed AOA could be wrong for several different reasons. For example: pilot fails to enter ballast correctly, error in any one of multiple dependent sensors, extraordinary bug loading, precipitation or other contamination on wing, erroneous calibration factors for aircraft (setup errors happen all the time). The point is that this is situation that calls for direct measurement so that it has independent, stand-alone usefulness and relaibility.

An inferred AOA might be interesting as a teaching tool but I don't think it's a flying tool.

On Wednesday, April 20, 2016 at 1:30:46 PM UTC-7, Jonathan St. Cloud wrote:
Read the first post of this thread to see example.

On Wednesday, April 20, 2016 at 1:19:30 PM UTC-7, Bruce Hoult wrote:

How exactly do you think a computer is going to calculate AoA without an AoA measurement? Using what inputs? IAS? TAS? AUW? G loading? What else?

I don't think you can do it, at least not well enough to me more useful than pilot feel. But I'm willing to be surprised.

Given airspeed, measured stall speed at specific weight, actual weight, and load factor (from an accelerometer), a flight computer can get a pretty approximation of the expected stall speed in normal straight or tuning flight.. Get the weight wrong, however (say using dry instead of wet weight), then the calculated stall speed will be wrong. During a winch launch, the wing is also being loaded by the rope, so the calculated stall speed will also be incorrect. By contrast, a properly installed AoA probe or vane will determine when you are approaching stall angle, independent of weight or any added loading during a winch launch...

I would also add that I think a direct measuring AOA sensor could help with thermalling performance -- most particularly if the slow, gooey computer operating the pitch plane might be replaced with a better one. There's an opportunity for a big soaring advance here, IMO.

On Thursday, April 21, 2016 at 1:02:51 AM UTC+3, wrote:
On Wednesday, April 20, 2016 at 1:30:46 PM UTC-7, Jonathan St. Cloud wrote:
Read the first post of this thread to see example.

On Wednesday, April 20, 2016 at 1:19:30 PM UTC-7, Bruce Hoult wrote:

How exactly do you think a computer is going to calculate AoA without an AoA measurement? Using what inputs? IAS? TAS? AUW? G loading? What else?

I don't think you can do it, at least not well enough to me more useful than pilot feel. But I'm willing to be surprised.

Given airspeed, measured stall speed at specific weight, actual weight, and load factor (from an accelerometer), a flight computer can get a pretty approximation of the expected stall speed in normal straight or tuning flight. Get the weight wrong, however (say using dry instead of wet weight), then the calculated stall speed will be wrong. During a winch launch, the wing is also being loaded by the rope, so the calculated stall speed will also be incorrect. By contrast, a properly installed AoA probe or vane will determine when you are approaching stall angle, independent of weight or any added loading during a winch launch...

It's worse than that.

Say you're well above S&L stall speed -- 50 knots say, in a 45º turn, and stalled. Or pulling out of a dive and stalled. The load factor will be less than the maximum CL load factor at that speed. But it might well be above 1.0.

e.g. if your S&L stall is 40 knots, then at 50 knots you can pull 1.56 G.

If you're at 50 knots and pulling 1.3 G, are you well above the stall .. or ARE YOU ALREADY STALLED?

Other than a direct measurement of AoA from a vane or differential pressure, I don't even know what kind of input you can give to your calculation to tell you that. Attitude (from gyro or multiple GPS receivers) won't help.

On Wednesday, April 20, 2016 at 3:20:09 PM UTC-7, Steve Koerner wrote:
I would also add that I think a direct measuring AOA sensor could help with thermalling performance -- most particularly if the slow, gooey computer operating the pitch plane might be replaced with a better one. There's an opportunity for a big soaring advance here, IMO.

Since we're dreaming big here and taking advantage of wireless electronics it would be great to have an AOA probe near each wingtip.

Craig

On Wednesday, April 20, 2016 at 11:30:46 PM UTC+3, Jonathan St. Cloud wrote:
Read the first post of this thread to see example.

On Wednesday, April 20, 2016 at 1:19:30 PM UTC-7, Bruce Hoult wrote:

How exactly do you think a computer is going to calculate AoA without an AoA measurement? Using what inputs? IAS? TAS? AUW? G loading? What else?

I don't think you can do it, at least not well enough to me more useful than pilot feel. But I'm willing to be surprised.

Yes, I've watched the video.

I simply don't believe it. It's marketing bull****. It might work in a GA plane, flown sedately. It's not going to work in a glider.

It doesn't even know the correct freaking current flap position! What;s it going to do in a glider with 5 or 6 flap settings in common use, and intermediate positions possible.

You really don't need an AoA gauge. An indexer will do just fine.
Here's a link to one example
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja &uact=8&ved=&url=http%3A%2F%2Fairfactsjournal.com% 2F2015%2F07%2Fsmoke-flames-report-ga-safety-picture-changing%2F&psig=AFQjCNGjTLiBuCDXvQMOmNlJQJJod6173 g&ust=1461287874599677.
Something could me made with a simple vertical stack of different
colored LEDs. You could mount one in the center of the glare shield,
one on each corner of the glare shield, or one on each canopy rail at
about the same position as the edge of the glare shield.

You don't have to look at them, you will see them peripherally.

On 4/20/2016 2:13 PM, wrote:
Thats when darwin takes over. Actually the wright bros were the first to develop and use an AOA way before we had airspeeds. But I dont think they will ever come into vogue. What I worry about is more cockpit distraction. By the time a guy hears, recognises and responds to an AOA horn honking, he is already into the sheeit too deep.

When I am instructing, before a student goes solo, we pick a good soaring day and work for over an hour on stall after stall, flying the edges of stall, accelerated and soecially turning at various bank angles. I jnow instructors who only take their students thru full stalls and never give them a good dose of tasting all the edges. I also do eyes closed sensing, and airspeed covered up sensing, etc. i want all the signs of inpending doom well ingrained in my students psyche.
Dan
Dan

--
Dan, 5J

Search the document that comes up when you follow the link, for the
string, AoA. You'll see the picture there.

On 4/20/2016 7:21 PM, Dan Marotta wrote:
You really don't need an AoA gauge. An indexer will do just fine.
Here's a link to one example
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja &uact=8&ved=&url=http%3A%2F%2Fairfactsjournal.com% 2F2015%2F07%2Fsmoke-flames-report-ga-safety-picture-changing%2F&psig=AFQjCNGjTLiBuCDXvQMOmNlJQJJod6173 g&ust=1461287874599677.
Something could me made with a simple vertical stack of different
colored LEDs. You could mount one in the center of the glare shield,
one on each corner of the glare shield, or one on each canopy rail at
about the same position as the edge of the glare shield.

You don't have to look at them, you will see them peripherally.

On 4/20/2016 2:13 PM, wrote:
Thats when darwin takes over. Actually the wright bros were the first to develop and use an AOA way before we had airspeeds. But I dont think they will ever come into vogue. What I worry about is more cockpit distraction. By the time a guy hears, recognises and responds to an AOA horn honking, he is already into the sheeit too deep.

When I am instructing, before a student goes solo, we pick a good soaring day and work for over an hour on stall after stall, flying the edges of stall, accelerated and soecially turning at various bank angles. I jnow instructors who only take their students thru full stalls and never give them a good dose of tasting all the edges. I also do eyes closed sensing, and airspeed covered up sensing, etc. i want all the signs of inpending doom well ingrained in my students psyche.
Dan
Dan

--
Dan, 5J

--
Dan, 5J