Re: Re: New file uploaded to Indoor_Construction

From: <leop_at_lyradev.com>
Date: 22 Mar 2016 17:19:55 -0700

There is some other interesting data for the West Baden Atrium "weather" last weekend. My wife and I were able to get some infrared thermal temperature data from the Atrium surfaces. For all of Saturday and early Sunday, the walls were warmer than the either the floor (actual floor) or ceiling girders (the walls are heated by the room HVAC systems). This contributes to a convection pattern the where the air goes up the walls and falls down in the center, as Mike mentioned. These thermal conditions did not change, even at night, as the floor stays cool radiating heat to the cold ceiling (and sky). On Sunday, just after lunch time, the cloud cover lessened and the floor (and upper girders) started to warm up. At about 3pm, the walls temperatures were no longer warmer than the floor and the more usual West Baden Atrium thermal pattern emerged as mentioned by Mike and Bill.
 

 There was something else contributing to the poor conditions on Saturday and very early Sunday morning. There were windows open to the second floor, many just over the office lobby entrance to the atrium (just counter clockwise to where the fliers were set up). The second floor and above air handlers were still turned on and this resulted in a significant airflow out the windows into the atrium (continuing in and out of the four main atrium entrances). Some of this air exited into the return air vents just below the second floor. This air flow contributed to the turbulence near the ground that made the flying so treacherous on Saturday (especially the turbulence resulting from the wind shear between the ground convection flow toward the walls and the inward flow from the windows and some entrances). After flying ended on Saturday, my wife and I traced this airflow. On Sunday morning, we closed the open second floor windows and used paper wedges to keep the windows from opening again (as they would open because the the second floor air pressure). I thought that the turbulence was much less when flying began again on Sunday morning and I was able to make successful quarter motor flights with two different F1D's. By 1:30pm, the turbulence has lessened enough to allow a good vp equipped F1D launch and an ascent all the way up to the "pancake." There was still a significant central downdraft (especially on the north or bar side of the atrium) at that time but conditions were improving . The serious and fun flying began.
 

 LeoP
  
Received on Tue Mar 22 2016 - 17:19:56 CET