# Zippered body tube

#### Marlin523

##### Well-Known Member
Which situation do you think is more likely to cause this? Deployment before apogee or after apogee?

#### stantonjtroy

##### Well-Known Member
One is as likely as another. It has less to do with where the rocket is on the balistic trajectory than velocity at the time of deployment. Haulin butt up or hualin butt down is still haulin butt.

##### Well-Known Member
After, as the rocket would be picking up speed. If it deployed before it would be rapidly drcellerating

#### new2hpr

##### Well-Known Member
Ditto Troy's answer. Same either way. I've had an early deploy at about 120mph. Talk about rapidly decelerating! Everything held, except 4 zippers of assorted sizes and directions

Data from the MAWD showed a sudden flat top to the curve!

-Ken

#### slogfilet

##### Well-Known Member
After, as the rocket would be picking up speed. If it deployed before it would be rapidly drcellerating

While this is true, it is not acceleration that is the problem, it's velocity. For example, hitting a an object with your car at 50mph will yield the same effect whether you were riding the breaks or the gas at the time.

#### Marlin523

##### Well-Known Member
Well said. For midpower rockets what range of velocity do you consider to be optimal. It isn't always easy to find a thrust/delay combination that deploys at apogee.

#### stantonjtroy

##### Well-Known Member
For most any rocket, 19 -28 feet per second isn't bad. Faster and you risk damage, slower and you take a walk. Peak altitude is a factor to consider. There are always exceptions. All this asumes single stage (apogee) deployment.

#### stantonjtroy

##### Well-Known Member
After, as the rocket would be picking up speed. If it deployed before it would be rapidly drcellerating

Rember that along a balistic trajectory velocity increases, decreases and increases at a comperable rate. Variances come from acceleration under thrust on the ascent and terminal velocity on the down side. Middle third follows the profile given here. (more or less)

#### Pantherjon

##### Well-Known Member
Could also be too short of shock cord causing the nosecone to 'rebound' from the ejection charge..

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