Recovery systems

[loxley]

Hello,

I'll cut straight to it.

Motor: Cesaroni P29-2G
Aprox. apogee: 1500m (16 seconds)
Length: 48.8 cm
Diameter: 3.6 cm

(All specs are subject to change)

So the motor has an in-built ejection charge with a delay of 13 seconds, so were going to disable it and use our own method. Currently I am planning on using a accelerometer and pressure sensor for apogee detection and then have a timer for a backup.

Igniters: I was thinking of using something like this for launching.

My issue is with how to deploy the parachute, we are only using a main parachute. Our current design, the rocket breaks in the middle (not nose cone) to deploy the parachute.

Q1: How does parachute deployment work? (I've looked at videos and papers, but I'm not confident in my knowledge)
Q2: What methods of deploying a parachute would be the most reliable and safest?

 

[Neutronium95]

I would strongly suggest that you have a backup method of parachute deployment whenever you use unproven electronics for deployment. Cesaroni motors have adjustable delays, so you could use that for a backup and just set it to go off a few seconds after apogee.

For lighting the motor, you don't need to make your own igniters, they come with the motor. Also I would not trust anything from TKOR in regards to rocketry. His videos on sugar motors are especially horrible.

The normal method of electronically actuated parachute deployment is a small black powder ejection charge that's actuated by an ematch. I like the MJG firewires. There are calculators online that will help you to figure out how much BP you'll need for a given charge.

Good luck and stay safe.

 

[loxley]

I would strongly suggest that you have a backup method of parachute deployment whenever you use unproven electronics for deployment. Cesaroni motors have adjustable delays, so you could use that for a backup and just set it to go off a few seconds after apogee.

For lighting the motor, you don't need to make your own igniters, they come with the motor. Also I would not trust anything from TKOR in regards to rocketry. His videos on sugar motors are especially horrible.

The normal method of electronically actuated parachute deployment is a small black powder ejection charge that's actuated by an ematch. I like the MJG firewires. There are calculators online that will help you to figure out how much BP you'll need for a given charge.

Good luck and stay safe.

Thank you for your reply, I know you can get a tool to adjust the delay but it decreases it. I wasn't involved in selecting the motor, and the team that selected it are pretty set on reaching X apogee, despite the time taken to reach apogee is longer than the motors delay. I will look into the BP some more, and your suggestions.

I will stay clear of TKOR videos

Warm regards.

 

[Voyager1]

If you can’t use motor ejection as backup, you would be advised to use a commercial altimeter as a backup to your untested deployment electronics, particularly if your apogee altitude is 1500 m (~5,000’).

Just out of curiosity, your rocket diameter of “2.6 cm“ is less than your motor diameter of 29 mm. Typo?

 

[loxley]

If you can’t use motor ejection as backup, you would be advised to use a commercial altimeter as a backup to your untested deployment electronics, particularly if your apogee altitude is 1500 m (~5,000’).

Just out of curiosity, your rocket diameter of “2.6 cm“ is less than your motor diameter of 29 mm. Typo?

Apologies, 2.6cm is a mistake. It's 3.6cm, thank you for the altimeter tip. I will bring that up to the team.

 

[dr wogz]

eggtimer quark
http://eggtimerrocketry.com/home/altimeters-av-bay/

 

[David Schwantz]

I have several Quarks, I don't know, like 20 of them. They are easy to use, small footprint. and reliable. And what ever method you use, ALWAYS ground test you system.

 

[loxley]

eggtimer quark
http://eggtimerrocketry.com/home/altimeters-av-bay/

That's really helpful thank you!

 

[user 35280]

Contact this group,
http://www.ukra.org.uk/

 

[cerving]

eggtimer quark
http://eggtimerrocketry.com/home/altimeters-av-bay/

If you only want to pop the chute at Apogee, an Eggtimer Apogee will do it, and it's $15. It's our easiest kit to build, too... almost all through-hole parts, and it has a built-in screw switch.

If you're not familiar with electronic deployments, I recommend that you read up on the subject... the book "Modern High Powered Rocketry 2" is an excellent resource for general knowledge (although some of the product references are rather dated).

 

[loxley]

If you only want to pop the chute at Apogee, an Eggtimer Apogee will do it, and it's $15. It's our easiest kit to build, too... almost all through-hole parts, and it has a built-in screw switch.

If you're not familiar with electronic deployments, I recommend that you read up on the subject... the book "Modern High Powered Rocketry 2" is an excellent resource for general knowledge (although some of the product references are rather dated).

Thank you, I will check that book out. Yes, I have added the eggtime apogee to our components list