Motor rotator is used on the pad to hold the motor.
Motor ejection involves blowing gas, which can cause problems due to Newton's third law.
Newton's third law: "You can only push on something as much as it resists your push."
Equal force applied in one direction results in an equal force in the opposite direction.
Tape is insufficient to hold the motor during ejection despite holding its weight.
Motor Casing Costs:
ARC casings: Approximately 90.
High power casings: Over 130.
K motor casings for SLI: Over 300.
Level three motor casings: 500.
Motor retention is crucial to prevent casing loss.
Fin Alignment:
Measure where the air flap goes to determine the bottom center line.
Measure the distance to ensure proper centering ring placement.
Centering rings should fit snugly between fin tabs.
Misalignment due to over sanding can prevent fin placement.
Gluing and Epoxy:
Superglue is used for quick initial adhesion.
Epoxy is applied for stronger, lasting strength during flight.
Apply superglue first, then epoxy over it.
Epoxy the inner ring and both sides.
Level one rockets typically need two centering rings; level two and above require three.
Chapter 2: Centering Ring
Knots:
Rocket knot: A quadruple knot threaded back through itself for secure fastening.
Bowline knot: Tightens as it's pulled, commonly used in SLI and scouting.
Avoid tying knots too tightly, as vibrations during flight can cause them to unwind.
Nut Security:
Secure nuts with epoxy to prevent them from unwinding due to vibrations during flight.
Ensure the cord is coming out the correct end before inserting and epoxying the motor mount.
Centering Ring Alignment:
Use Z-clips or screws as temporary handlebars to align the centering ring.
Do not glue the body weight on; focus on internal fillets.
Epoxy Fillets:
Apply epoxy fillets thoroughly to ensure the motor mount is securely glued in place.
Use a yardstick, barbecue skewer, or metal rod to create epoxy fillets around the hole outside.
After the epoxy dries, remove the temporary centering ring.
Fin Attachment:
Add an epoxy layer around the motor tube for extra structural support.
Simultaneously attach the fins, ensuring they are aligned.
Use a fin jig or paper with a drawn circle and measured lines to ensure fin alignment.
Apply epoxy fillets to all fin joints, with more epoxy on the inside than the outside.
Chapter 3: Bottom Ring Back
Inner Fillets:
Spend more time on inner epoxy fillets for high-power rockets.
After the epoxy dries, remove Z-clips or screws.
Add more epoxy, then push the ring completely flush with the fin tabs to ensure proper motor path operation.
Motor Tube Length:
Measure the length of the largest motor you plan to use and cut the motor tube accordingly to avoid unnecessary excess length.
Measurements:
Put on the arrow pack and measure where it goes, then measure for the centering ring above the motor pack.
Line up the fin taps and push down another centering ring.
For level one, two centering rings are fine; for higher levels, use three.
Apply superglue to hold the centering ring in place, then add epoxy for strength.
Insert the tube with one centering ring into the bottom section, ensuring the tube sticks out a bit for the AeroPak.
Align the fins and bottom centering ring, using screws as handlebars for alignment.
Internal Fillets
Epoxy the ring firmly inside, then remove the bottom ring.
Add internal fillets along the inner and outer tubes for added strength.
Align the fins using a drawn rocket diameter and protractor lines.
Final Assembly
Superglue the fins for alignment, then create internal fillets.
Put the bottom ring back on, sliding epoxy on the fins and pushing the ring all the way in.
Ensure the ring is pushed all the way down for the arrow path to fit, then add another epoxy layer.
Chapter 4: Put on Bottom
Bottom Rail Button:
Put on the bottom rail button, depending on its placement.
Centering Rings:
Do not over sand centering rings; tighter fits are better for alignment.
Nuts:
Secure nuts with epoxy to prevent loosening due to vibrations during high-power launches.
Couplers:
Epoxy acts as a lubricant for couplers, making sliding easier; apply epoxy to both the tube and coupler.
Ensure at least half of the coupler is inside the tube, following kit instructions for measurements.
Nose Cones:
Sand down the plastic ridge on the nose cone for a smooth finish.
Motors:
Use thrustcurve.com to find motors with a stable thrust curve.
Avoid motors with high impulse or long burn times.
Thrust-to-weight ratio should be at least 5:1.
Maintain a safe rail exit velocity of 50 feet per second off the pad (approximately 16.67 meters per second).
*Fin Alignment:
*The fins only work at a certain speed to help align the rocket to any can