FAQ

This page lists various frequently asked questions. Most of these are categorized as "How to" questions for various design issues.

Using OpenRocket

How do I create a clustered rocket?

Clusters can be created using the Cluster tab of an Inner tube. This allows you to cluster the inner tubes in various configurations, distances and angles. The motor selected for the inner tube will be used for all the inner tubes in the cluster, and any components (such as engine blocks) attached to the inner tube will be replicated for all of the inner tubes.

If you need more fine-grained control on what components are in which tubes, you can create the cluster this way and then split the cluster into individual components by clicking Split cluster. You can then modify the individual components of the cluster. Note that you cannot re-assemble a split cluster (except with undo).

Note that you can create clusters of clusters by attaching inner tubes to other inner tubes, but the motors attached to such configurations will not be counted up correctly! This is a known bug that will be addressed in later versions.

The cluster techniques can also be combined with a staged rocket.

How do I create a staged rocket?

First, the components belonging to different stages must be attached to separate stage components. You can add stages to the rocket by clicking the New stage button on the main design window. Stages are always used from the lowest to the highest, and when an upper-stage motor ignites all lower stages are automatically dropped off.

The motor ignition event can be selected on the Motor tab of the body tubes or inner tubes. The default is Automatic, which is suitable for small rockets, where the ejection charge of the lower stage lights up the upper stage motors. The lowest stage will be ignited at launch.

In larger staged rockets that don't have ejection charges the ignition event must be changed. The first stage to light up should ignite at Launch (or Automatic). If the latter stages are ignited by an onboard computer that detects deceleration, they should be set to First burnout of previous stage. (Note that this assumes the lower stage motors have equal burn lengths.) If the latter stage is ignited by a timer, the event should be set to Launch and a suitable delay added.

Each of the events can take an additional delay parameter. This allows taking into account for example the time for an ejection charge to light up the next stage or the time for an onboard computer to ignite the next stage. It can also be used for timed ignition, by setting the ejection event to Launch plus n seconds.

The staging techniques can also be combined with a clustered rocket.