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Using new variometer technology to display real time lift coefficient?



 
 
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  #11  
Old February 7th 17, 10:24 PM posted to rec.aviation.soaring
Bruce Hoult
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Default Using new variometer technology to display real time lift coefficient?

On Tuesday, February 7, 2017 at 9:42:02 PM UTC+3, wrote:
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?).


Having to input weight and wing area (which admittedly doesn't change on most gliders) before flight seems like not only a pain and error-prone but also not entirely useful as different wing profiles have different useful max CL as well, and that is not published information even for "as new" gliders.

Maybe better to do an in-flight calibration where the pilot flies the glider briefly at their personal comfort limit near the stall and presses a button to calibrate the instrument. This could be done in straight and level flight, with the pilot judging it by buffet, sink rate, sound from airflow breaking away from the wings or whatever. Or it could be done in the first in-anger thermal.

Maybe also have "+1 knot" and "-1 knot" buttons to fine tune it later.
  #12  
Old February 7th 17, 10:44 PM posted to rec.aviation.soaring
ND
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Default Using new variometer technology to display real time lift coefficient?

On Tuesday, February 7, 2017 at 1:42:02 PM UTC-5, wrote:
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?).


i think good training is better than making an instrument "think for you" in this case. good fundamental training allows you to recognize an oncoming stall. outsroucing it to an instrument is needless, and in my opinion more dangerous than doing this one the old fashioned way. you have to learn to feel the glider. your ass is a more sensitive instrument for this purpose. like evan said, use the force. having said that, i've read some stuff about people putting yaw strings on the side of their canopy and making the critical angle of attack. THAT is a poor man's AOA.
  #13  
Old February 8th 17, 12:05 AM posted to rec.aviation.soaring
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Default Using new variometer technology to display real time lift coefficient?

Training is frequently the answer, and yet things that should be overcome by training keep happening.

Maybe we need training on how to do training so we can train the trainers.

9B

On Tuesday, February 7, 2017 at 1:44:38 PM UTC-8, ND wrote:

i think good training is better than making an instrument "think for you" in this case. good fundamental training allows you to recognize an oncoming stall. outsroucing it to an instrument is needless, and in my opinion more dangerous than doing this one the old fashioned way. you have to learn to feel the glider. your ass is a more sensitive instrument for this purpose. like evan said, use the force. having said that, i've read some stuff about people putting yaw strings on the side of their canopy and making the critical angle of attack. THAT is a poor man's AOA.

  #14  
Old February 8th 17, 12:33 AM posted to rec.aviation.soaring
Bruce Hoult
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Posts: 961
Default Using new variometer technology to display real time lift coefficient?

On Wednesday, February 8, 2017 at 12:44:38 AM UTC+3, ND wrote:
On Tuesday, February 7, 2017 at 1:42:02 PM UTC-5, wrote:
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?).


i think good training is better than making an instrument "think for you" in this case. good fundamental training allows you to recognize an oncoming stall. outsroucing it to an instrument is needless, and in my opinion more dangerous than doing this one the old fashioned way. you have to learn to feel the glider. your ass is a more sensitive instrument for this purpose. like evan said, use the force. having said that, i've read some stuff about people putting yaw strings on the side of their canopy and making the critical angle of attack. THAT is a poor man's AOA.


I don't feel any need for this instrument myself. I'm perfectly happy doing minimum controllable airspeed exercises and recognising the onset of the stall with my own senses. Often when I'm sitting back and letting someone else fly I'll be hearing the airflow sound change as gusts partially stall the wing. Suggest to them that they fly a couple of knots faster and suddenly we're climbing much better.
  #15  
Old February 8th 17, 07:27 AM posted to rec.aviation.soaring
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Default Using new variometer technology to display real time lift coefficient?

One can use stall speed to calculate the CL max.
  #16  
Old February 8th 17, 03:44 PM posted to rec.aviation.soaring
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Default Using new variometer technology to display real time lift coefficient?

Thanks to all for the useful input. I was mostly interested in throwing this topic up in the air, and seeing where it landed.

For myself, I agree with a previous post that training is important. Indeed, I would argue that training gives the best reward for the time spent.

However, you can supplement training with other goodies (most everyone is flying with some sort of TE compensation for their varios, some have varios that depict the real time wind vector, and many have moving map displays with little tiny ‘amoebas’ crawling all over them for example…)

Someone alluded to seat-of-the-pants flying to ‘feel’ how close you are flying to the stall. This works, and is used by all of us most of the time. I submit that when a pilot is distracted (low level circling in a rough thermal, on a windy day, with the associated drift illusions, and then throw in a FLARM target….) perhaps his feel may be momentarily masked or overridden….Then, wouldn’t it be nice to have a little audio ‘blip’ to warn us that we are suddenly 5% above the stall?

In addition, if we follow this seat of the pants flying to a logical extreme, perhaps we should get rid of the ASI (fly attitude), and also drop the altimeter (we can, after all, look at how big the houses and trees are getting).

Thanks again for all the thoughts.

rp
  #17  
Old February 8th 17, 05:35 PM posted to rec.aviation.soaring
Tango Eight
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Default Using new variometer technology to display real time lift coefficient?

On Wednesday, February 8, 2017 at 9:44:26 AM UTC-5, wrote:

if we follow this seat of the pants flying to a logical extreme, perhaps we should get rid of the ASI (fly attitude), and also drop the altimeter (we can, after all, look at how big the houses and trees are getting).


That's my favorite lesson! 20 minutes spent thermalling with no ASI improves just about anyone's flying. No altimeter patterns are excellent practice as well. I cannot recommend too highly. Excellent BFR and Spring check ride material too.

best,
Evan Ludeman / T8
  #18  
Old February 8th 17, 07:41 PM posted to rec.aviation.soaring
Bruce Hoult
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Posts: 961
Default Using new variometer technology to display real time lift coefficient?

On Wednesday, February 8, 2017 at 5:44:26 PM UTC+3, wrote:
Thanks to all for the useful input. I was mostly interested in throwing this topic up in the air, and seeing where it landed.

For myself, I agree with a previous post that training is important. Indeed, I would argue that training gives the best reward for the time spent.

However, you can supplement training with other goodies (most everyone is flying with some sort of TE compensation for their varios, some have varios that depict the real time wind vector, and many have moving map displays with little tiny ‘amoebas’ crawling all over them for example…)

Someone alluded to seat-of-the-pants flying to ‘feel’ how close you are flying to the stall. This works, and is used by all of us most of the time. I submit that when a pilot is distracted (low level circling in a rough thermal, on a windy day, with the associated drift illusions, and then throw in a FLARM target….) perhaps his feel may be momentarily masked or overridden….Then, wouldn’t it be nice to have a little audio ‘blip’ to warn us that we are suddenly 5% above the stall?

In addition, if we follow this seat of the pants flying to a logical extreme, perhaps we should get rid of the ASI (fly attitude), and also drop the altimeter (we can, after all, look at how big the houses and trees are getting).


Legally-required minimum equipment.

We had (and won) a fight against the local tower guys several years ago. When we called "joining" they told us (along with the traffic, which is useful) the QNH and expected us to read it back. We told them it's a waste of everyone's time and that by the time we've decided to join circuit we're not looking at the altimeter any more. We also convinced them to only tell us about the traffic actually in or very near the circuit, not the ones still five minutes away.

We have students who are near solo do a flight or two with instruments covered. Not a big deal even in a heavy and slippery glider such as the DG1000. I wouldn't want to try to do an outlanding into a 100m field without ASI, but if you've got 400 or 500 meters of space then it's just not an issue.
  #19  
Old February 9th 17, 06:21 PM posted to rec.aviation.soaring
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Default Using new variometer technology to display real time lift coefficient?

Speaking of technology I just watched a seminar by Infineon - they make sensors. In the pressure transducer they make for exercise trackers can have high definition to tell that someone is climbing or descending stairs or help determine what kind of activity they are doing.
They can sense a air pressure difference of 50mm/2 inches!!!

These were energy efficient for use with battery powered systems of course.

Chris
  #20  
Old February 9th 17, 06:44 PM posted to rec.aviation.soaring
Richard[_9_]
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Default Using new variometer technology to display real time lift coefficient?

On Thursday, February 9, 2017 at 9:21:16 AM UTC-8, wrote:
Speaking of technology I just watched a seminar by Infineon - they make sensors. In the pressure transducer they make for exercise trackers can have high definition to tell that someone is climbing or descending stairs or help determine what kind of activity they are doing.
They can sense a air pressure difference of 50mm/2 inches!!!

These were energy efficient for use with battery powered systems of course.

Chris


I remember being told that the sensors used in the LXNAV equipment measure 1cm or altitude 100 time per second.

Richard
www.craggyaero.com
 




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