Dick Johnson methodology for measuring glider performance

Before Richard Johnson's passing, I was communicating with him regarding a glider performance test (an ASW20) and he was kind enough to send me some Excel spreadsheets showing the parameters that he was focusing on. As expected, he used KTAS for the glide performance calculations. What caught me by surprise was his glide calculations used computed TRUE SINK as well. This might have made sense to me if he was measuring vertical speed with a rate instrument but unless I am mistaken, he measured sink rate using an altimeter and a stop watch.

I did not get the chance to ask him about this.

Nevertheless, he is missed.
Paul
ZZ

ZZ wrote on 7/12/2016 9:00 PM:
What caught me by surprise was his glide calculations used computed
TRUE SINK as well. This might have made sense to me if he was
measuring vertical speed with a rate instrument but unless I am
mistaken, he measured sink rate using an altimeter and a stop watch.

Since the altimeter (properly corrected) would give true altitude loss,
and the stop watch would give true duration, I think (altitude
loss)/(duration) would give true sink rate.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf