A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Where is the LX S80?



 
 
Thread Tools Display Modes
  #1  
Old November 4th 14, 02:00 PM posted to rec.aviation.soaring
waremark
external usenet poster
 
Posts: 377
Default Where is the LX S80?

Surprised that software features of S80 are not up to V7 currently. What is excluded?

Wonder whether it will become a better vario since it has more sensors. It costs much more than V7.
  #2  
Old November 3rd 14, 06:13 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
external usenet poster
 
Posts: 608
Default Where is the LX S80?

On Monday, November 3, 2014 7:15:06 AM UTC-8, pete purdie wrote:
Like I said, we didn't attempt to fully model the
mechanism.

Richard Feynmen: 'If the measurements don't agree with
the theory, then the theory is probably wrong. If they do,
the theory might be right.'


Truth.
  #3  
Old November 4th 14, 09:38 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
external usenet poster
 
Posts: 608
Default Where is the LX S80?

On Monday, November 3, 2014 6:38:22 AM UTC-8, Andy Blackburn wrote:
Not entirely sure I buy momentum as a first-order effect since blue thermals don't typically overrun the top of the invasion level by very much, so I can't imagine the top 2/3 of the thermal is simply momentum. Also, if it's thoroughly mixed from a temperature perspective wouldn't it also be mixed from a humidity perspective as well so it wouldn't be rising from having higher humidity either?

Curious.

9B


I did the simple physics on this. A volume of air rising at 600 fpm with no other forces acting on it other than gravity has enough momentum to rise an additional 1.6 feet before its upward velocity reaches zero.

I am now officially at a loss as to why thermals go up if there is no temperature difference versus the surrounding air.

9B
  #4  
Old November 4th 14, 11:04 PM posted to rec.aviation.soaring
Evan Ludeman[_4_]
external usenet poster
 
Posts: 484
Default Where is the LX S80?

On Tuesday, November 4, 2014 4:38:33 PM UTC-5, Andy Blackburn wrote:
I did the simple physics on this. A volume of air rising at 600 fpm with no other forces acting on it other than gravity has enough momentum to rise an additional 1.6 feet before its upward velocity reaches zero.

I am now officially at a loss as to why thermals go up if there is no temperature difference versus the surrounding air.

9B


That's for an object in a vacuum. The thermal isn't surrounded by a vacuum, it's surrounded by air at almost precisely the same density.

T8
  #5  
Old November 5th 14, 12:23 AM posted to rec.aviation.soaring
Andy Blackburn[_3_]
external usenet poster
 
Posts: 608
Default Where is the LX S80?

On Tuesday, November 4, 2014 3:04:41 PM UTC-8, Evan Ludeman wrote:
On Tuesday, November 4, 2014 4:38:33 PM UTC-5, Andy Blackburn wrote:
I did the simple physics on this. A volume of air rising at 600 fpm with no other forces acting on it other than gravity has enough momentum to rise an additional 1.6 feet before its upward velocity reaches zero.

I am now officially at a loss as to why thermals go up if there is no temperature difference versus the surrounding air.

9B


That's for an object in a vacuum. The thermal isn't surrounded by a vacuum, it's surrounded by air at almost precisely the same density.

T8


Wouldn't that make it go up even less due to the frictional resistance?
  #6  
Old November 4th 14, 08:03 AM posted to rec.aviation.soaring
krasw
external usenet poster
 
Posts: 668
Default Where is the LX S80?

On Monday, 3 November 2014 16:15:05 UTC+2, pete purdie wrote:
As should have been clear from what I wrote, in the bottom third of the
thermal the air is still warmer, but steadily mixing in surrounding air.
Once properly formed the momentum of the tons of air moving is presumed to
keep the circulation active. Air close to the ground is also more humid
which increases the buoyancy. We did not fully model the mechanism, just
took measurements that illustrated the scale and characteristics of
meso-scale air motion in a range of situations, including convective
weather.


At 13:33 03 November 2014, Andy Blackburn wrote:
On Monday, November 3, 2014 3:15:06 AM UTC-8, pete purdie wrote:
...An important finding is that above about
one-third of the distance to the inversion, there is no significant
temperature difference between the thermal and surrounding air; near

the
inversion the temperature is actually lower since the warmer air above

the
inversion is being mixed down around the rising air. Humidity is a
significant indicator, H2O molecules being lighter than O2 or N2.


So thermals rise, not because of the sun heating the ground and making a
bubble of warm air that breaks free, but because somehow a more humid
bubble of air is created. What mechanism creates the bubble of humidity?

9B



Interesting study:

http://journals.ametsoc.org/doi/abs/...B%3E2.0.CO%3B2

Figure 6 gives quite good overview of temperature and humidity variability during (weakish) convective activity. Temp. differences are appr. 0,5 deg and humidity 1 g/kg close to ground.

Other Weckwerth papers are worth reading too, IMHO.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 07:43 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 AviationBanter.
The comments are property of their posters.