When I started ground launching, I was told that the glider taking off
often kicks off a thermal is there was a bubble of warm air that the
glider passed through. Because of that, on my ground launch safaris, I
always made a U-turn after release and flew back down the runway. I got
away every time from about 700'. Maybe I was just lucky...

On 10/9/2015 4:30 PM, BobW wrote:
One reason winch or auto tows are not more popular is that you are
released
over the airpark. In an aero tow you can be towed to the lift before
releasing. Yes, I know usually on soft days there is a thermal just
as one
turns downwind to base, but that is not the best place to thermal.

Hmmm...

I suspect this "truth" is more a statement of "the way aerotows
normally are" than "the realities of usable lift distribution."
Reality as a self-fulfilling prophecy, maybe?

In any event, BTDT insofar as brain-picking for "local knowledge" and
"locations of house thermals," but my experience throughout launch
sites (mostly aerotow) in the intermountain west (mostly Colorado and
New Mexico) has me concluding I can't think of one locale where it's
*necessary* to "tow over there" in order to find usable lift. Sure,
some plains sites along the east slope of the Colorado Rockies tend to
start later than a tow into nearby uplands, but my observation has
been very few of the locals routinely take advantage of that fact when
time of launch is considered as a function of release point. IOW, many
tows "go to the hills" just because they can, and not because it's
necessary. Every single one of my launch sites has had convective lift
with easy reach of "above pattern height" releases, for ships of the
ubiquitous 2-33-35:1 performance range.

As for auto towing (exposed to that before winching, I was),
popularity (or lack thereof) has to do - so I reckon - with lack of
familiarity; neither auto towing or winching have been "popular"
("common" is probably a better descriptor) in the U.S. because
whatever critical mass may once have existed disappeared when "cheap
towplanes" became the norm after WW-II. Where they exist(ed), my
experience has been both were "hugely popular."

Bob W.

--
Dan, 5J