Stu has a lot of experience flying in the colorado high country so I respect
his views. However. I'd like to make a few comments below.
wrote in message
ups.com...
Hmmmm,

I don't see consulting charts as the solution...rather just another
data point. I choose to fly where most days the density altitude at
launch is somewhere between 10k'-12k'(Salida, Buena Vista, Leadville,
Telluride). I have never considered constructing a graph....not that
it might not help. I try to launch by 11am, downhill if possible, no
water if behind a Cub, plenty of water if behind a 260Pawnee, no mid
afternoon launches into strong thermal conditions. I like at least
7500' of runway. Pawnees are not great climbers at 70 knots, and I
have done my share of fence inspection tours grinding around low. I
accept the risk/reward by refusing to fly with water if I have any
doubts...and just a couple of degrees of temperature can make a huge
difference IMVHO.

All reasonable precautions.

Having flown in these conditions for the last 9 years, piloting and
fuel load affect the safety of the launch as much as POH climb
prediction. Ever towed behind a pilot who had not set the fuel
mixture correctly? Or did not stay down in ground effect to
accelerate? Or with a big guy at the stick who just topped off the
tanks?

Unfortunately, I have seen all this happen - it is the mark of a very poor
pilot. I try not to get to know them since I don't want to be invited to
their funeral.

ANY properly trained airplane pilot knows how to use takeoff charts which
includes knowing the takeoff weight including fuel and pilot weights as well
as density altitude and wind. Adding glider weight and L/D doesn't add that
much work. Properly done, the results will be very accurate. I've never
seen actual takeoff performance differ from the POH by more than 5% - most
often it's dead on.

Pilots of airplanes with fixed pitch propellers can set the mixture simply
by adjusting for max RPM. This is, by definition, max power which is about
100 degrees rich of peak EGT. You can't hurt an engine at high density
altitudes doing this so set it for max power for every takeoff. If you can
hold constant airspeed, this works while climbing too so max power can be
maintained througout the climb.

I would be curious what the predicted climb rate for the Cessna
150/180 based at Telluride would be on a hot day...not sure I really
would want to know

Actually, I would want to know so I can exercise my PIC and perhaps decline
the tow if I deem the performance too low.

Bill Daniels