Erik, I think you and Jim Staniforth have identified the key issue. Five pilots in four glider types at one site experiencing low tow speed handling problems behind one tow plane point to the ASI in the Pawnee reading incorrectly.

I searched the RAS archives and found a thread from 1997 discussing Pawnee ASIs reading too high, ie, giving the glider a low speed tow. Several posts blame the Pawnee ASI static arrangement (it seems in some Pawnees the ASI static ports to the cockpit while in others the ASI static goes to fuselage static ports). It is claimed that the first is affected by ventilation use, while the second is influenced by propeller airflow. One post asked if anyone had tried using the static that was a part of his pitot probe, but got no answer.

So apparently Pawnee ASI errors are known and of a long standing nature. Is there any good fix?

-John, Q3


On Sunday, November 10, 2013 8:14:13 AM UTC-5, Papa3 wrote:
I've towed with my LS8 at many sites in many different conditions behind many different towplanes, and I've never had the problem you describe at an IAS (on my side) of above 65 kts. If the Pawnees (PGC?) were truly doing 80mph (70 kts), I can't imagine how this would be described as a "slow tow".. I've had tows that dropped down into the low 60s or even high 50s (kts) where it felt squirrely, but that's a full 10kts slower than what you are describing.

Just a data point.

P3