Here is a new method of chute deployment that ought to work nicely... the pictures tell the story. Angle from below...
Angle from above....
The black tube is a film canister that has had the bottom cut off... it's mounted to a hinge between two fins, and is spring or rubberband loaded to flip into the deploy position (away from the red faring). It is held in the "closed" position by an elastic cord connected to a tomy timer (both unseen in this rendering). Of course, the 'chute lives inside the film canister, and is tied off to the bottom of the rocket, for a nose-down landing attitude, which is good for the OS2 rocket since it's nose is an easily replacable 2L pete bottle.
The cool thing about this is that it uses the slipstream to deploy... if it opens late, and the rocket is heading downward, the faster it goes, the more likely it is to be pushed out. No more stuck 'chutes!