Water Rockets with Parachutes (2014)

All about Water Rockets - NASA
US Water Rockets
H2O Rockets

Backsliders - Water Rockets without Parachutes (2011-2013)

Science Olympiad Tips

YouTube Videos:
http://www.youtube.com/watch?v=rM_GGZLSNjU
http://www.youtube.com/watch?v=L2GdjnKr28Y This one is in slow motion and has stills to study the position in their air.
http://www.youtube.com/watch?v=ZzISqrnKZf8&feature=related
http://www.youtube.com/watch?v=KZqAp7baeUg&feature=related A Science Olympiad one (2nd launch is better)

Random Info:
It seems like they can also be called a "Coney" by Robert Youen
http://txsnapper.eezway.org/waterrocketguy/backslider.html Robert Youen's site
http://scioly.org/wiki/Bottle_Rocket Science Olympiad (lots of links at the end)
http://waterrocket.uh-lab.de/backglide.htm Construction/Robert Youen's site
http://www.aircommandrockets.com/recovery_guide.htm