Now, now Eric.

A launch uses less than 800ml ( 1 quart) of petrol on our prehistoric inefficient Ford V8 powered winch. That is an
average over decades of use...

That gives around 1300 to 1700 feet AGL depending on wind, aircraft and skill - add some fuel for the retrieve and you
are still around 1 litre per launch with our winch (almost exclusively big heavy old two seaters). Newer multi drum
designs are a lot better.

I expect the average self launcher is using a lot more than that to get to the first thermal. Average engine time is
apparently around 5 minutes. (Schleicher figure)

Assume you have a strong SLMG say an ASH26 which claims 3.4m/s climb. You need 2.7 minutes of full power climb + run up
+ ground run + shut down to end at the same height.
The AE50R is relatively fuel efficient, (most SLMGs are two strokes) but it is still developing around 37kw for 4-5
minutes. Max power at 6900RPM uses 16 litres in 75 minutes - so five tach minutes gives you 1.06 litres.

Remarkably similar to a winch.

Just my bit of matchbox arithmetic - I assume you have actual fuel consumption numbers?

Of course the bottom line is that the fuel used in either launch mode is far exceeded by the trip to the airfield for
almost everyone, and is negligible in comparison to the work commute. My 216km round trip to the glider field uses
around 18l if I am VERY well behaved.

I find that the economy on my work commute is exceptional when I work from home.

Bruce

Eric Greenwell wrote:
Martin Gregorie wrote:
On Sun, 19 Oct 2008 08:18:10 -0700, Brad wrote:

As a bottom feeder in the economic food chain, when all gliders that are
flying are motorgliders, I'll be looking at all the pictures I took when
I used to be able to fly a non-powered sailplane. Since it will be
somewhat impossible for me to ever afford a powered sailplane.

No complaints, just an honest asessment.

Move near to a winching site and you'll have the last laugh as fuel
prices go sky high.

Doesn't a winch launch use more fuel than a self-launch? And won't the
fuel he uses to commute to work eat into any savings from winch launching?