On Monday, April 30, 2012 10:28:14 AM UTC-4, WB wrote:

The towplane I used to have in a partnership (Tim McGowin's C-175) is
pretty close to a 170. It has a 180 hp engine with CS prop and a STOL
kit. It is definitely not a Pawnee, but it tows two-seaters just fine at
our field with 5000 ft runways. It has also towed 2 seaters at much
shorter fields like Chilhowee and Moontown. it will tow a sports class
grid almost as efficiently as a Pawnee. However, it doesn't climb very
well at the speeds preferred by those flying heavily watered ships. That
has cut into it's contest towing.


I have real-world experience towing behind just such a setup. With an LS8 watered-up to just 9lbs on a hot (90F) day towing off a 5,000 foot long paved runway, it was "acceptable", but barely. While we were airborne and moving at a pretty good clip at the end of the runway, we were a good 100 feet lower than with a 235 Pawnee or even a PA-18 (180 conversion). This was tested over the course of several launches and results were consistent. What it meant was fewer options in the event of a ropebreak and a longer period of WTF-Do-I-Do-Know pucker .