Improved shear/stall-spin alarms

[KiloKilo[_2_]]

I just wondering if current technology could provide improved stall-spin warnings/information.

For example, suppose you installed a pitot at each wingtip (and I'm making an assumption you need this level of resolution) and had an instrument that monitored/stored wingtip airspeed and fluctuations … and had inertial inputs that could provide information about how cleanly you were flying the ship.

This data would be evaluated relative to a flight envelope (algorithm and envelope would have to be developed)– and if you were near the envelope boundaries – because of atmospheric conditions (gusts or shear) … or how you were flying the ship (slipping or skidding) … or if you were close to the ground/terrain … alerts would display/sound. (Could this be a feature of our modern varios.)

Or do we consistently fly too close (or over) an envelope edge to allow this to work in practice.

KK

[Bill D]

On Sunday, June 9, 2013 6:55:36 AM UTC-6, KiloKilo wrote:
> I just wondering if current technology could provide improved stall-spin warnings/information.
>
>
>
> For example, suppose you installed a pitot at each wingtip (and I'm making an assumption you need this level of resolution) and had an instrument that monitored/stored wingtip airspeed and fluctuations … and had inertial inputs that could provide information about how cleanly you were flying the ship.
>
>
>
> This data would be evaluated relative to a flight envelope (algorithm and envelope would have to be developed)– and if you were near the envelope boundaries – because of atmospheric conditions (gusts or shear) … or how you were flying the ship (slipping or skidding) … or if you were close to the ground/terrain … alerts would display/sound. (Could this be a feature of our modern varios.)
>
>
>
> Or do we consistently fly too close (or over) an envelope edge to allow this to work in practice.
>
>
>
> KK

The key variable to monitor is angle of attack. Other than in the landing flare, there is no reason or need to operate a glider at an angle of attack greater than that for minimum sink. There's a fairly wide angle of attack range between min sink and stall where a slow/stall warning could be set so it isn't overly intrusive.

The Angle of attack probe itself can be just two pressure ports in the nose..

The warning itself could be lights, sounds or my preference, a stick vibrator like the ones in cell phones. Since most gliders have glide computers with AGL altitude, the warnings could be more insistent when low.

[Dan Marotta]

Technology is a wonderful thing and, given the time and money, we engineers
can develop anything you desire.

BUT... Would another bell or whistle really improve safety over simply
learning to fly correctly? Have we become so insulated from our
surroundings that we can't recognize a burble in the controls,a slacking of
pressure, a reduction in air noise?

In the 80s it was temperature probes on the wingtips in the hope that
detecting a slightly different temperature would have us turning into warmer
(rising?) air.

As was said earlier, it's AoA that you're looking for. They've already got
it; for civilian aircraft, too. Look here:
http://www.aircraftspruce.com/menus/in/angleofattackindicators.html


"Bill D" > wrote in message
...
On Sunday, June 9, 2013 6:55:36 AM UTC-6, KiloKilo wrote:
> I just wondering if current technology could provide improved stall-spin
> warnings/information.
>
>
>
> For example, suppose you installed a pitot at each wingtip (and I'm making
> an assumption you need this level of resolution) and had an instrument
> that monitored/stored wingtip airspeed and fluctuations … and had inertial
> inputs that could provide information about how cleanly you were flying
> the ship.
>
>
>
> This data would be evaluated relative to a flight envelope (algorithm and
> envelope would have to be developed)– and if you were near the envelope
> boundaries – because of atmospheric conditions (gusts or shear) … or how
> you were flying the ship (slipping or skidding) … or if you were close to
> the ground/terrain … alerts would display/sound. (Could this be a feature
> of our modern varios.)
>
>
>
> Or do we consistently fly too close (or over) an envelope edge to allow
> this to work in practice.
>
>
>
> KK

The key variable to monitor is angle of attack. Other than in the landing
flare, there is no reason or need to operate a glider at an angle of attack
greater than that for minimum sink. There's a fairly wide angle of attack
range between min sink and stall where a slow/stall warning could be set so
it isn't overly intrusive.

The Angle of attack probe itself can be just two pressure ports in the nose.

The warning itself could be lights, sounds or my preference, a stick
vibrator like the ones in cell phones. Since most gliders have glide
computers with AGL altitude, the warnings could be more insistent when low.

[Bill D]

On Sunday, June 9, 2013 9:19:11 AM UTC-6, Dan Marotta wrote:
> Technology is a wonderful thing and, given the time and money, we engineers can develop anything you desire.

> BUT... Would another bell or whistle really improve safety over simply learning to fly correctly? Have we become so insulated from our surroundings that we can't recognize a burble in the controls,a slacking of pressure, a reduction in air noise?

___________________

Some form of AoA sensing/stall warning is installed on every aircraft made - except rotorcraft and gliders. The sling-wing guys have an excuse, we don't. I think our terrible safety record speaks volumes.

Clearly, pilots don't universally recognize impending stall/spins. We've been trying to get them to do so for the entire history of flight without much success. It time for another solution now that we have the technology.

[Eric Greenwell[_4_]]

Bill D wrote, On 6/9/2013 9:04 AM:
> On Sunday, June 9, 2013 9:19:11 AM UTC-6, Dan Marotta wrote:
>> Technology is a wonderful thing and, given the time and money, we
>> engineers can develop anything you desire.
>
>> BUT... Would another bell or whistle really improve safety over
>> simply learning to fly correctly? Have we become so insulated from
>> our surroundings that we can't recognize a burble in the controls,a
>> slacking of pressure, a reduction in air noise?
>
> ___________________
>
> Some form of AoA sensing/stall warning is installed on every aircraft
> made - except rotorcraft and gliders. The sling-wing guys have an
> excuse, we don't. I think our terrible safety record speaks
> volumes.
>
> Clearly, pilots don't universally recognize impending stall/spins.
> We've been trying to get them to do so for the entire history of
> flight without much success. It time for another solution now that
> we have the technology.

Has anyone tried any of various AOA instruments on the market? There are
several under $1000.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

[Bill D]

On Sunday, June 9, 2013 2:57:47 PM UTC-6, Eric Greenwell wrote:
> Bill D wrote, On 6/9/2013 9:04 AM:
>
> > On Sunday, June 9, 2013 9:19:11 AM UTC-6, Dan Marotta wrote:
>
> >> Technology is a wonderful thing and, given the time and money, we
>
> >> engineers can develop anything you desire.
>
> >
>
> >> BUT... Would another bell or whistle really improve safety over
>
> >> simply learning to fly correctly? Have we become so insulated from
>
> >> our surroundings that we can't recognize a burble in the controls,a
>
> >> slacking of pressure, a reduction in air noise?
>
> >
>
> > ___________________
>
> >
>
> > Some form of AoA sensing/stall warning is installed on every aircraft
>
> > made - except rotorcraft and gliders. The sling-wing guys have an
>
> > excuse, we don't. I think our terrible safety record speaks
>
> > volumes.
>
> >
>
> > Clearly, pilots don't universally recognize impending stall/spins.
>
> > We've been trying to get them to do so for the entire history of
>
> > flight without much success. It time for another solution now that
>
> > we have the technology.
>
>
>
> Has anyone tried any of various AOA instruments on the market? There are
>
> several under $1000.
>
>
>
> --
>
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
>
> email me)
>
> - "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
>
> http://tinyurl.com/yb3xywl

I don't know if there is one designed from the beginning as a glider instrument. Here's what I have in mind:
http://www.technology-market.eu/partneriai/Profiles/10_CH_84FB_3IDG.html

Except, there's no need for a separate probe, just use the glider's nose as a probe's nose cone and add the pressure sensing ports.

[Don Johnstone[_4_]]

At 16:04 09 June 2013, Bill D wrote:
>On Sunday, June 9, 2013 9:19:11 AM UTC-6, Dan Marotta wrote:
>> Technology is a wonderful thing and, given the time and money, we
>engineers can develop anything you desire.
>
>> BUT... Would another bell or whistle really improve safety over simply
>learning to fly correctly? Have we become so insulated from our
>surroundings that we can't recognize a burble in the controls,a slacking
of
>pressure, a reduction in air noise?
>
>___________________
>
>Some form of AoA sensing/stall warning is installed on every aircraft
made
>- except rotorcraft and gliders. The sling-wing guys have an excuse, we
>don't. I think our terrible safety record speaks volumes.
>
>Clearly, pilots don't universally recognize impending stall/spins. We've
>been trying to get them to do so for the entire history of flight without
>much success. It time for another solution now that we have the
>technology.

Why don't they? If they are properly trained they should. If they are
regularly checked they should.
A lot more time is spent, IMHO too much time, teaching the recovery from a
stall/spin and far too little time is making sure that people do really
recognise the signs of an approaching stall. Knowing the recovery from a
stall and being super reactive in applying corrective action for a fully
developed spin in the final turn is more likely to kill you that letting
the spin continue. Recognising the signs of an approaching stall and taking
the corrective action will save you every time. Recognising the signs of an
approaching stall is not difficult so why do people get caught out.
The problem with replacing skill and good practice with technology is that
people come to rely on the technology and when it fails are completely
screwed.
As a very experienced airline pilot put it. Automatic take off, automatic
flying and automatic landing = automatic crash.

[son_of_flubber]

On Sunday, June 9, 2013 12:04:54 PM UTC-4, Bill D wrote:

>
> Some form of AoA sensing/stall warning is installed on every aircraft made - except rotorcraft and gliders.

Do many pilots recount hearing the stall alarm on the turn to final and then saving their own butt? Or are stall alarms only effective when they go off high above the ground?

[Bill D]

On Sunday, June 9, 2013 9:27:16 PM UTC-6, son_of_flubber wrote:
> On Sunday, June 9, 2013 12:04:54 PM UTC-4, Bill D wrote:
>
>
>
> >
>
> > Some form of AoA sensing/stall warning is installed on every aircraft made - except rotorcraft and gliders.
>
>
>
> Do many pilots recount hearing the stall alarm on the turn to final and then saving their own butt? Or are stall alarms only effective when they go off high above the ground?

Most definitely! Low altitude is where they save your butt.

[Dan Marotta]

I've found stall horns annoying in high performance flying. It's the
physical signals the airplane gives, not alarms, that tell me a stall is
imminent. You should really learn to feel the aircraft and not rely on
horns, bells, whistles, gauges, etc. They WILL fail some day...


"Bill D" > wrote in message
...
> On Sunday, June 9, 2013 9:27:16 PM UTC-6, son_of_flubber wrote:
>> On Sunday, June 9, 2013 12:04:54 PM UTC-4, Bill D wrote:
>>
>>
>>
>> >
>>
>> > Some form of AoA sensing/stall warning is installed on every aircraft
>> > made - except rotorcraft and gliders.
>>
>>
>>
>> Do many pilots recount hearing the stall alarm on the turn to final and
>> then saving their own butt? Or are stall alarms only effective when they
>> go off high above the ground?
>
> Most definitely! Low altitude is where they save your butt.

[Bill D]

On Monday, June 10, 2013 9:03:38 AM UTC-6, Dan Marotta wrote:
You should really learn to feel the aircraft and not rely on
> horns, bells, whistles, gauges, etc. They WILL fail some day...

Straw man argument.... 99.9% of the time they don't fail and they save lives.

I can assure I do know what an impending stall feels like. However, for most people, it doesn't take much distraction for them to miss the sensations.. Our miserable safety record proves that.

The entirety of aviation, excluding gliders, has found AoA/stall warning systems necessary whether it's high performance jets or airliners. Presumably, the professionals flying them can feel a stall developing but their stall warning systems are still a no-go item.

[Dan Marotta]

Yes, I know that the MEL requires a lot of stuff. Still, what do you do
when it fails?

My argument is not so much about the equipment as it is about slavishly
relying on devices to bring you home. You WILL have electrical failure some
day and will have to actually read a map, land visually, respond to light
signals from a control tower, pick up a wing with rudder instead of aileron.
Your 99.9% argument omits the 0.1% and that's a lot higher number than the
number of accidents per 100,000 flying hours.

Aviation requires nothing but skill and attention in maintenance and
operation. Bells and whistles are mandated by the barn door closers.


"Bill D" > wrote in message
...
On Monday, June 10, 2013 9:03:38 AM UTC-6, Dan Marotta wrote:
You should really learn to feel the aircraft and not rely on
> horns, bells, whistles, gauges, etc. They WILL fail some day...

Straw man argument.... 99.9% of the time they don't fail and they save
lives.

I can assure I do know what an impending stall feels like. However, for
most people, it doesn't take much distraction for them to miss the
sensations. Our miserable safety record proves that.

The entirety of aviation, excluding gliders, has found AoA/stall warning
systems necessary whether it's high performance jets or airliners.
Presumably, the professionals flying them can feel a stall developing but
their stall warning systems are still a no-go item.

[Michael Huber]

>> Has anyone tried any of various AOA instruments on the market?
>> There are
>> several under $1000.

> Except, there's no need for a separate probe, just use the glider's
> nose as a probe's nose cone and add the pressure sensing ports.

If you are looking for a simple DIY AoA indicator you might want to
check http://www.akaflieg.tugraz.at/akagproj.html
Parts cost around $20, and you can build it in an evening. The
downside is that there is no good integration with XCSoar yet, but
that might change if there is enough interest.

Michael

[Vaughn]

On 6/10/2013 11:39 AM, Bill D wrote:
> The entirety of aviation, excluding gliders, has found AoA/stall warning systems necessary
> whether it's high performance jets or airliners.

I don't fly either jets or airliners, but I can tell you that the
average Joe learning to fly in, or renting, an old Cezzna probably can't
hear the stall alarm because they were never designed to overpower the
noise isolation of today's headsets.

[Bill D]

On Monday, June 10, 2013 12:31:24 PM UTC-6, Michael Huber wrote:
> >> Has anyone tried any of various AOA instruments on the market?
>
> >> There are
>
> >> several under $1000.
>
>
>
> > Except, there's no need for a separate probe, just use the glider's
>
> > nose as a probe's nose cone and add the pressure sensing ports.
>
>
>
> If you are looking for a simple DIY AoA indicator you might want to
>
> check http://www.akaflieg.tugraz.at/akagproj.html
>
> Parts cost around $20, and you can build it in an evening. The
>
> downside is that there is no good integration with XCSoar yet, but
>
> that might change if there is enough interest.
>
>
>
> Michael

The electronics look clever but putting a vane on a fin-mounted TE probe isn't going to work for anything but measuring the wing's down-wash angle. A vane needs to be on the nose well ahead of the wing where, unfortunately, it's likely to get broken. To me, pressure ports on the top and bottom of the nose cone seems the least intrusive.

[Bill D]

On Monday, June 10, 2013 12:40:43 PM UTC-6, Vaughn wrote:
> On 6/10/2013 11:39 AM, Bill D wrote:
>
> > The entirety of aviation, excluding gliders, has found AoA/stall warning systems necessary
>
> > whether it's high performance jets or airliners.
>
>
>
> I don't fly either jets or airliners, but I can tell you that the
>
> average Joe learning to fly in, or renting, an old Cezzna probably can't
>
> hear the stall alarm because they were never designed to overpower the
>
> noise isolation of today's headsets.

Well...as one data point, my hearing isn't great and I wear an excellent noise cancelling headset but I can plainly hear a Cessna stall warning.

[Vaughn]

On 6/10/2013 3:03 PM, Bill D wrote:
> Well...as one data point, my hearing isn't great and I wear an excellent noise cancelling headset
> but I can plainly hear a Cessna stall warning.
I can't, and that's with about a decade of experience with a pretty wide
selection of rental Cezznas using both passive and electronic headsets.
Surely I'm not alone.

[Bill D]

On Monday, June 10, 2013 4:14:38 PM UTC-6, Vaughn wrote:
> On 6/10/2013 3:03 PM, Bill D wrote:
>
> > Well...as one data point, my hearing isn't great and I wear an excellent noise cancelling headset
>
> > but I can plainly hear a Cessna stall warning.
>
> I can't, and that's with about a decade of experience with a pretty wide
>
> selection of rental Cezznas using both passive and electronic headsets.
>
> Surely I'm not alone.

Audible warnings are not the right thing anyway what with all the toots and beeps in glider cockpits. A light plus a cellphone vibrator motor in the stick grip seems better.

[Eric Greenwell[_4_]]

Dan Marotta wrote, On 6/10/2013 9:04 AM:
> Yes, I know that the MEL requires a lot of stuff. Still, what do you do
> when it fails?
>
> My argument is not so much about the equipment as it is about slavishly
> relying on devices to bring you home. You WILL have electrical failure
> some day and will have to actually read a map, land visually, respond to
> light signals from a control tower, pick up a wing with rudder instead
> of aileron. Your 99.9% argument omits the 0.1% and that's a lot higher
> number than the number of accidents per 100,000 flying hours.
>
> Aviation requires nothing but skill and attention in maintenance and
> operation. Bells and whistles are mandated by the barn door closers.

Yes, devices fail, but so do people. If the device fails less often than
the people, would you accept the device as useful?

My experience is I fail more often than the devices, such as gear
warnings, slow speed warnings, automatic hookups, and more. My radios
have worked reliably, but I haven't always set the frequency correctly.
I made more mistakes with paper maps than I ever did because the GPS
failed, and I've flown more hours with GPS than with maps.

I think each device has to be evaluated for efficacy, not discarded
because it might fail some day. If we treated pilots the same way, there
would be no pilots, either.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

[Michael Huber]

From: "Bill D" >

>The electronics look clever but putting a vane on a fin-mounted TE
>probe isn't going to work for anything but measuring the wing's
>down-wash angle.

Trust me, this position works fine for a glider, the only reason to
change it would be a retractable engine. The vane is of course
affected by down-wash, but as an approximation, down-wash angle is
proportional [1] to the angle of attack. This means an angle measured
in this position is not really the angle of attack, but an angle
proportional to AoA. With proper calibration this is just as fine for
the purpose of a stall warning.

The sensor itself could be placed in any position (remember, it´s
wireless), but for a glider stall warning device the TE probe is a
reasonable compromise.

Michael

[1] Down-wash is not proportional to AoA anymore close to the critical
AoA, but it still works.

[Bill D]

On Tuesday, June 11, 2013 1:22:59 PM UTC-6, Michael Huber wrote:

"Trust me"

I don't.

"it still works"

Only in the loosest possible definition of "works".

The wing's downwash is affected in a big way by a lot of things unrelated to AOA. To get free of the wings near-field effects an AOA probe needs to be several wing chords ahead of the LE which is why you see air-data nose booms on test aircraft. Find me an example of an aircraft with the AOA probe aft of the wing.

Nose cone sensors would be too close to the wing as well but the location has proven adequate in a large number of aircraft. Come to think of it, I saw a photo of Mark Mocho's Pegasus with the TE probe on the nose which makes a lot of sense aerodynamically - if a line boy doesn't trip over it.

[Michael Huber]

>>"Trust me"
>I don't.
I agree, don´t trust, test it youself . Build it, see if it works for
you at the TE probe, test other locations, improve it and give it back
to the gliding community. It´s $20 for material and some fun time
spent on a hobby, so there´s not a lot to loose.

>which is why you see air-data nose booms on test aircraft.
Flight testing is a pretty different application with different
requirements than a simple DIY glider stall warning, isn´t it?

>Nose cone sensors would be too close to the wing as well but the
>location has proven adequate in a large number of aircraft
As you say, not a perfect location, but a reasonable compromise.

>Come to think of it, I saw a photo of Mark Mocho's Pegasus with the
>TE probe on the nose which makes a lot of sense >aerodynamically - if
>a line boy doesn't trip over it.
Aerodynamically better position with usability issues vs. fin mounted
probe as a reasonable compromise for most pilots, same situation as
for the AoA sensor position.

Michael

[Ralph Jones[_3_]]

On Mon, 10 Jun 2013 12:00:58 -0700 (PDT), Bill D >
wrote:

[snip]
>
> To me, pressure ports on the top and bottom of the nose cone seems the least intrusive.

What about contamination by runway crud?

rj

[Bill D]

On Tuesday, June 11, 2013 4:27:04 PM UTC-6, Ralph Jones wrote:
> On Mon, 10 Jun 2013 12:00:58 -0700 (PDT), Bill D >
>
> wrote:
>
>
>
> [snip]
>
> >
>
> > To me, pressure ports on the top and bottom of the nose cone seems the least intrusive.
>
>
>
> What about contamination by runway crud?
>
>
>
> rj

No worse than static ports or pitot tubes. The ports I'm thinking of would be just like static ports - flush with the surface.