Improved shear/stall-spin alarms

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.

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.

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

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.

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.

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.

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.

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.

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

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.