Using new variometer technology to display real time lift coefficient?

A question respectfully submitted to the pundits who lurk in these halls:

Please forgive me if this topic has been covered before; I have done a general search on this forum and have found no mention of it anywhere.

Having been away from Soaring for about 35 years, and having just come back last summer, I have been slowly re-immersing myself. Some things have not changed all that much, but wow, have varios ever changed a lot!

My question:

With the new generation of varios out there, specifically those that incorporate inertial sensors, would it not be advantageous for these varios to offer the possibility to the pilot of displaying the sailplane’s real time lift coefficient, CL? It would seem to me that while thermalling, this display would be useful as a ‘lift reserve indicator’, directly related to AOA. No extra sensors would be required, since these new generation varios have all the inputs necessary to calculate CL (i.e. total pressure, static pressure, g force, with the aircraft mass and wing area presumably entered on the ground, before the flight). Granted, the pilot would have to know his max CL for different flap settings, but that’s it!

Would not such a display be desirable?

Has this been implemented already, and I am not aware of this?

I have recently implemented this with a sensor box with inertial sensors and airspeed.
I looked at the flight envelope during aerobatics.

It is nice, but it changes constantly.
I fly a flapless glider.

On Tuesday, 7 February 2017 02:13:59 UTC-5, wrote:
I have recently implemented this with a sensor box with inertial sensors and airspeed.
I looked at the flight envelope during aerobatics.

It is nice, but it changes constantly.
I fly a flapless glider.

Ok; perhaps a vertical bar depicting CL rather than an actual number.... Thanks for your input.

On Monday, February 6, 2017 at 10:56:51 PM UTC-5, wrote:
A question respectfully submitted to the pundits who lurk in these halls:

Please forgive me if this topic has been covered before; I have done a general search on this forum and have found no mention of it anywhere.

Having been away from Soaring for about 35 years, and having just come back last summer, I have been slowly re-immersing myself. Some things have not changed all that much, but wow, have varios ever changed a lot!

My question:

With the new generation of varios out there, specifically those that incorporate inertial sensors, would it not be advantageous for these varios to offer the possibility to the pilot of displaying the sailplane’s real time lift coefficient, CL? It would seem to me that while thermalling, this display would be useful as a ‘lift reserve indicator’, directly related to AOA. No extra sensors would be required, since these new generation varios have all the inputs necessary to calculate CL (i.e. total pressure, static pressure, g force, with the aircraft mass and wing area presumably entered on the ground, before the flight). Granted, the pilot would have to know his max CL for different flap settings, but that’s it!

Would not such a display be desirable?

Has this been implemented already, and I am not aware of this?

Use the Force, Luke....

On Tuesday, 7 February 2017 15:36:20 UTC, Tango Eight wrote:
On Monday, February 6, 2017 at 10:56:51 PM UTC-5, wrote:
A question respectfully submitted to the pundits who lurk in these halls:

Please forgive me if this topic has been covered before; I have done a general search on this forum and have found no mention of it anywhere.

Having been away from Soaring for about 35 years, and having just come back last summer, I have been slowly re-immersing myself. Some things have not changed all that much, but wow, have varios ever changed a lot!

My question:

With the new generation of varios out there, specifically those that incorporate inertial sensors, would it not be advantageous for these varios to offer the possibility to the pilot of displaying the sailplane’s real time lift coefficient, CL? It would seem to me that while thermalling, this display would be useful as a ‘lift reserve indicator’, directly related to AOA. No extra sensors would be required, since these new generation varios have all the inputs necessary to calculate CL (i.e. total pressure, static pressure, g force, with the aircraft mass and wing area presumably entered on the ground, before the flight). Granted, the pilot would have to know his max CL for different flap settings, but that’s it!

Would not such a display be desirable?

Has this been implemented already, and I am not aware of this?

Reichmann pointed out the potential value of a lift coefficient meter in his book. If a meaningfully useable one could be made it would be very helpful for thermalling and as a safety feature.

On Monday, February 6, 2017 at 10:56:51 PM UTC-5, wrote:
A question respectfully submitted to the pundits who lurk in these halls:

Please forgive me if this topic has been covered before; I have done a general search on this forum and have found no mention of it anywhere.

Having been away from Soaring for about 35 years, and having just come back last summer, I have been slowly re-immersing myself. Some things have not changed all that much, but wow, have varios ever changed a lot!

My question:

With the new generation of varios out there, specifically those that incorporate inertial sensors, would it not be advantageous for these varios to offer the possibility to the pilot of displaying the sailplane’s real time lift coefficient, CL? It would seem to me that while thermalling, this display would be useful as a ‘lift reserve indicator’, directly related to AOA. No extra sensors would be required, since these new generation varios have all the inputs necessary to calculate CL (i.e. total pressure, static pressure, g force, with the aircraft mass and wing area presumably entered on the ground, before the flight). Granted, the pilot would have to know his max CL for different flap settings, but that’s it!

Would not such a display be desirable?

Has this been implemented already, and I am not aware of this?

Sounds like you are trying to find a use for stuff in the instruments.
My question would be what are you trying to accomplish?
UH

At 16:24 07 February 2017,
wrote:
On Monday, February 6, 2017 at 10:56:51 PM UTC-5,

wrote=
:
A question respectfully submitted to the pundits who lurk
in these halls:
=20
Please forgive me if this topic has been covered before;
I have done a
=
general search on this forum and have found no mention of
it anywhere.
=20
Having been away from Soaring for about 35 years, and
having just come
ba=
ck last summer, I have been slowly re-immersing myself.
Some things have
n=
ot changed all that much, but wow, have varios ever
changed a lot!
=20
My question:
=20
With the new generation of varios out there, specifically
those that
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rporate inertial sensors, would it not be advantageous for
these varios
to=
offer the possibility to the pilot of displaying the
sailplane=E2=80=99s
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eal time lift coefficient, CL? It would seem to me that while
thermalling,=
this display would be useful as a =E2=80=98lift reserve
indicator=E2=80=99=
, directly related to AOA. No extra sensors would be
required, since
these=
new generation varios have all the inputs necessary to
calculate CL (i.e.
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total pressure, static pressure, g force, with the aircraft
mass and wing
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rea presumably entered on the ground, before the flight).
Granted, the
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=80=99s it!
=20
Would not such a display be desirable?
=20
Has this been implemented already, and I am not aware
of this?

Sounds like you are trying to find a use for stuff in the
instruments.
My question would be what are you trying to accomplish?
UH

Doesn't an extra "yaw string", mounted on the vertical side
of the canopy, tell you the angle of attack (roughly)? I think
it's all explained on the DG website. No electronics involved.

Also did that. Works great, and shows nice things during spins!

I think audio aoa makes most sense, but you also have the audio vario.
Somehow intuitively providing feedback on attitude/velocity during thermalling might improve the tendency to thermal with a too shallow bank angle,or flying the incorrect velocity for the bank angle.

Too much audio - too many distractions. How about a vibrating seat
cushion? It could be programmed to increase the frequency and amplitude
of the vibrations as AoA increased and give you an electric shock just
before the critical angle is reached. Of course, if you have a sore
back, you'd be flying around at too high an AoA just for the good
vibrations... =-O

On 2/7/2017 11:15 AM, wrote:
Also did that. Works great, and shows nice things during spins!

I think audio aoa makes most sense, but you also have the audio vario.
Somehow intuitively providing feedback on attitude/velocity during thermalling might improve the tendency to thermal with a too shallow bank angle,or flying the incorrect velocity for the bank angle.

--
Dan, 5J

Sounds like you are trying to find a use for stuff in the instruments.
My question would be what are you trying to accomplish?
UH


Goal: To increase the pilot's awareness of how close to the stall the aircraft actually is. This could be of some use during thermalling flight, especially at low level or when encountering gusty conditions. A poor man’s AOA meter, if you will. If properly implemented, it should help avoid stall/spin accidents... I believe that aircraft landing on carriers carry such technology (AOA indicator), as well as certain business jets. Before the days of microprocessors, this would have been difficult to implement. See Soaring magazine, March 1975 to give you an idea of pre-microprocessor attempts to do this.

Since many modern varios already have sensors receiving and interpreting the required inputs to calculate CL, it should be simply a software modification to actually calculate this value. Perhaps the most difficult part of the whole implementation would be to present the pilot with this information so that it would be useful to him (Visual? Audio?).