Thermal Velocities

[JSoar]

I have been test flying my new self-launching ultralight sailplane
design this fall, and it is going well. The Red Tail Hawk so far looks
like it has a glide ratio of around 21/1 at about 60 mph, which is at
the low end of the range of what was expected. But it has a minimum
sink of about 250 fpm at around 50 mph, which is worse than I had
hoped.

I have subscribed to XC Skies and have been watching the soaring
forecasts for tops of useable lift and thermal velocity for about a
month now, and seeing some 300 to 400' thermal velocities predicted
these fall days. That rate does not leave a lot left for climb at the
250 fpm sink rate of the Red Tail Hawk.

I'm in the central Illinois area. What I was wondering is what kind of
thermal velocities might I expect for next year during the prime part
of the soaring season. Is there some easy to read historical data
somewhere I could go thru? Or does anyone here have any anecdotal data
they could provide?

Thanks in advance,
Jerry Booker
http://groups.yahoo.com/group/RedTailHawkUltralightSailplane/

[Frank Whiteley]

On Oct 18, 8:22*am, JSoar > wrote:
> I have been test flying my new self-launching ultralight sailplane
> design this fall, and it is going well. The Red Tail Hawk so far looks
> like it has a glide ratio of around 21/1 at about 60 mph, which is at
> the low end of the range of what was expected. But it has a minimum
> sink of about 250 fpm at around 50 mph, which is worse than I had
> hoped.
>
> I have subscribed to XC Skies and have been watching the soaring
> forecasts for tops of useable lift and thermal velocity for about a
> month now, and seeing some 300 to 400' thermal velocities predicted
> these fall days. That rate does not leave a lot left for climb at the
> 250 fpm sink rate of the Red Tail Hawk.
>
> I'm in the central Illinois area. What I was wondering is what kind of
> thermal velocities might I expect for next year during the prime part
> of the soaring season. Is there some easy to read historical data
> somewhere I could go thru? Or does anyone here have any anecdotal data
> they could provide?
>
> Thanks in advance,
> Jerry Bookerhttp://groups.yahoo.com/group/RedTailHawkUltralightSailplane/

1. If you don't have SeeYou, download a copy here
http://www.naviter.si/products/seeyou.php?Itemid=213
The evaluation copy will allow you to examine flight logs.

2. Go to the OLC and register so you can log in.
http://www.onlinecontest.org/olc-2.0/gliding/daily.html?rt=olc&sc=&c=US&df=&st=olc&sp=2011

Change soaring region to USA>>Region 7
Change OLC Scoring to Statistic:Airfield
Change period by year. Find the airfields nearest you then click on
them to find the flights. Click the info button for the flight on the
right. From there you can see the flight log and download the IGC
file (after logged in) and start your analysis for the dates.

Frank Whiteley