Recently it has dawned on me that I am not entirely sure the best way to choose the right delay. Talking single-use motors here, where I can only choose from a set of standard delays. Is it better to err on the short or long side? How long is *too* long?
This problem is most acute when simming with Aerotech SU motors, e.g. the E20 or E30, where delays of 4 and 7 seconds are available (let's not mention the F44, which comes in -4 and -8 only). For whatever reason, a lot of my rockets seem to show ideal delays of about 5 seconds. In that case, using a -4 would give a decent low-speed deployment, but I've read that early deployment can result in the parachute not being ejected properly, or becoming tangled. Choosing a 7 second delay means a full 2 seconds late, or deployment north of 30 mph, which seems quite late to me.
If the flight trajectory is less than perfectly vertical, then a shorter delay would be better, although I don't know how much shorter.
So what's the right way to approach this?
This problem is most acute when simming with Aerotech SU motors, e.g. the E20 or E30, where delays of 4 and 7 seconds are available (let's not mention the F44, which comes in -4 and -8 only). For whatever reason, a lot of my rockets seem to show ideal delays of about 5 seconds. In that case, using a -4 would give a decent low-speed deployment, but I've read that early deployment can result in the parachute not being ejected properly, or becoming tangled. Choosing a 7 second delay means a full 2 seconds late, or deployment north of 30 mph, which seems quite late to me.
If the flight trajectory is less than perfectly vertical, then a shorter delay would be better, although I don't know how much shorter.
So what's the right way to approach this?