Staging, Clustering, and Complexity Why add complexity? Improve - PowerPoint PPT Presentation

Staging, Clustering, and Complexity

Why add complexity? • Improve the performance of your rocket • Meet design specifications • Fly to greater altitudes (or space) • Prove your engineering capabilities • It looks cool • Impress that special someone

Why avoid complexity? • Complexity usually leads to higher costs • Risk of failure • Difficulty of design or construction

Staging low-power rockets Ejection delay timer

Staging

Direct staging of low- power rockets • Black powder ignites very easily • Motors can be staged using the ejection charge of the booster motor • Upper stage motors must be reasonably close to the booster motor to prevent cooling of ejection gases • Can also be staged using electronic timers or switches

Gap staging of low-power rockets • Very similar to direct staging • Add vent holes to allow hot gas to reach the staged motor • Vent holes should be no larger than 0.25” in diameter • Avoid spacing stages too far apart (>10 inches)

Staging with composite motors • Composite motors take a long time to ignite, and thus cannot be directly staged • Use electronic staging timer or pre-programmed flight computer • Most staging timers work by sending a charge some number of seconds after an acceleration event • Remote staging is possible and can prevent unwanted staging events

General staging tips • Be sure to couple the stages together, but do not use glue • Shear pins are not recommended, either • Allow components to vent to prevent premature separation (p inside >p outside )

Staging “Do” and “Don’t” Do Don’t • Forget to arm any electric • Watch your CP/stability arming systems for each stage • Use plugged motors for • Check all staging timers hot gas method and delay timers for the • Seal off motor mounts correct values when using direct and • Add vents where gap staging necessary • Forget about motor retention • Forget about recovery

Why stage? • Fly higher (remember Newton’s Second Law) by reducing the mass flown in a given stage • Staging is difficult, and thus a good engineering challenge • Start small (low power) and work your way up for optimal success • Finally put those C6-0 motors to use

Clustering

Clustering • Group multiple motors together on the same stage • Cluster only BP motors with other BP motors or only composite motors with other composite motors – Allows all motors in a cluster to ignite • BP motors can be clustered using a clip whip • Because of high current draw, composite motors may require ignition by electronics

Clustering “Do” and “Don’t” Do Don’t • Be mindful of the CG • Cluster black powder when adding motors to a motors with composite cluster (stability) motors* • Carefully align all motors • Asymmetrically cluster to prevent unbalanced motors moments • Add enough motors to • Carefully install all allow the thrust-to-weight igniters, plugs, and leads ratio to fall below 5 • Pay attention to the polarity of a given lead

Why cluster? • Add more thrust to a single stage • Boost the altitude capabilities of a rocket • Induce a spin (flying saucers)

Thrust Vectoring • Angling a motor any direction other than directly up the longitudinal axis of your rocket • In commercial rockets, useful for stability and control without using fins • NAR/TRA frown upon active guidance, so use in a cluster to cancel out unbalanced moments

Experimental Motors • Restricted to research launches for Tripoli Level 2 and up, or non-sanctioned launches • Requires knowledge of chemistry, thermodynamics, heat transfer, and compressible flow • Dangerous to make, but can produce powerful and/or visually interesting propellants • Significantly cheaper than commercial motors despite a high start-up cost • Significant probability of failure

Experimental Motors