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

• f 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

• f 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 (pinside>poutside)

Staging “Do” and “Don’t”

Do

• Watch your CP/stability

for each stage

• Check all staging timers

and delay timers for the correct values

• Add vents where

necessary Don’t

• Forget to arm any electric

arming systems

• Use plugged motors for

hot gas method

• Seal off motor mounts

when using direct and gap staging

• 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
• ther 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

• Be mindful of the CG

when adding motors to a cluster (stability)

• Carefully align all motors

to prevent unbalanced moments

• Carefully install all

igniters, plugs, and leads

• Pay attention to the

polarity of a given lead Don’t

• Cluster black powder

motors with composite motors*

• Asymmetrically cluster

motors

• Add enough motors to

allow the thrust-to-weight ratio to fall below 5

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