Ballast dump time Discus

Ballast dump times are usually nothing but a reasonable guess so I
decided to measure them. Put a Discus CS wing on the standards
(horizontal) and filled her up. Times are for one wing thus double the
volume for real life and with vent holes as in flight.

20L: 73 seconds
40L: 105 seconds
60L: 150 seconds

That'll be 4.4, 8.8 and 13.2 gallons

Measuring the tail tank showed a strange result; dumping 2L took about
80/90 seconds but dumping 4L took over 10 minutes with only
significant dumping when the scotch from the "4L" and "3L" marks were
removed. With the scotch on the vent holes there was barely any
dumping though the upper two vent holes were definitely open. A club
member suggested that the water was polluted a bit and that using
fresh drinking water should solve this. I decided however that I won't
use tail ballast. But then that's easy to say if you're only 60 kg's I
guess ;-)

Hope this'll be usefull for some people.

J. Nieuwenhuize.