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Random things u should know (you don't have to know it to pass the exam but ya should know it)

• HPR = high-powered rocketry
• FAR = Federal Aviation Regulations
• NFPA = National Fire Protection Association
• CATO = catastrophe (catastrophic failure of a launch - for example, the motor explodes)
• LCO = launch control officer
• RSO = range safety officer
• CP = center of pressure
• CG = center of gravity

Answers are in blue. Particularly important things to know (not just for the exam, but in general) are in orange.

Section A: Applicable Regulations (*N-s = Newton-seconds)

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• When may onboard energetics and/or electronic controls be activated and when shall they be inhibited? Inhibited until in launching position and prior to removing from launch position. May be activated when non-essential personnel leave the pad area
• What equipment is required at launch sites? Fire suppression devices, first aid kits and a method of communicating with everyone on the launch site
• When flying an unproven design, it is not acceptable to: fly it as a "head-up" flight on the first flight
• Your HPR lands in a power line: you must leave it alone and call the power company
• Prohibited activity on launch day: consumption of alcohol, use of medication that could affect judgement, movement or stability
• Store HPR, motor reloading kits and pyrotechnics: at lease 25 feet from smoking, open flame, etc.

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• Which of these igniters may be ignited by continuity test of some launch controllers? Flashbulbs, very low current electric matches
• Unless manufacturer instructs otherwise, igniters for clustered rocket motors should be wired together in: parallel
• When should igniters be checked for continuity? Only on the launch pad, while installed in a rocket motor
• When clustering combos of black powder and composite motors: composite motors ignited first (slower to ignite)
• If individual igniters are used for igniting clustered model's motors: launch control must provide additional current to ignite the additional igniters
• Advantages of using a "relay" type launch control: can deliver more power to motor igniters (shorter wires = higher power)
• Titanium sponge: ingredient used in some rocket motors that causes them to eject sparks in exhaust
• Not required feature of rocket motor ignition system: audible or visual indicator showing continuity through the rocket motor igniter

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• Most likely to cause CATO of black powder rocket motor: temperature cycling
• Petroleum-based lubricants should not be used with oxygen or nitrous-oxide systems used in hybrids. Why? Risk of spontaneous ignition or explosion
• Safety hazards associated with hybrid rocket motors: high pressure gas, low temperatures (frostbite)
• A rocket returned from flight with "zipper" damage (shock cord tears through the model) is caused by: parachute ejection occuring too soo, after motor burnout AND occuring too late after apogee
• A payload section (with a heavy payload) separates immediately after motor burnout. The cause: payload shoulder too loose AND rocket motor had failure of its delay system
• Consequences of inadequate motor retention: motor being ejected at apogee instead of the parachute AND motor being ejected from the cluster and flying on its own AND motor flying through the rocket, destroying it
• According to NAR, the vast majority of unsuccessful flights are because of: recovery system failures
  

Being responsible and all that

• If the range safety officer (RSO) says that your model is unsafe to fly: back to square one! The RSO's decision can't overturned by anyone.
• The final authority in permitting an HPR to fly is the: range safety officer (RSO)
• The ultimate responsibility to ensure that the rocket was built in a safe manner falls with the: rocket owner/builder (that's you!)
• When can launch organisers violate NAR safety code? When local laws are followed, and 2/3 NAR Board of Trustees give written permissionpermiss
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Glue and attaching things

• Preferred method of attaching fins: "through the wall" mounting
• Which adhesive should not be used on rubber (or elastic) shock cord? Superglue (CA) (CA = cyanoacrylate)
• Which adhesive is most likely to be weakened under humid/wet conditions? White "Elmer's" glue
• Best adhesive for motor mount construction w/ phenolic motor tubes? Slow-curing epoxy adhesives
• Best adhesive for strong joint (centering ring): Slow-curing epoxy adhesives

Section D: Rocket Stability

• For a rocket to be stable: the center of pressure must be behind the center of gravity (CP behind CG)
• An unstable rocket can be made stable by: adding sufficient weight to the nose cone
• Rocket stability can be measured by: determining the relative positions of the CP and CG
• A rocket's CP can be estimated by: the "Barrowman" method AND the "cardboard cutout" method
• An unstable rocket can be made stable by: increasing the size of the aft fins
• During boost, a rocket powered by solid rocket motors tends to become: more stable in flight
• Which can cause unstable flight? Weak tubes/couplers AND misaligned motor mount AND inadequate speed
• How far should the CP be from the CG? CP should be at least 1.0 body tube diameters behind the CG

Section E: Rocket Motor Designations

• General naming system for a motor:        H-5
  • Letter (H) = total power range or impulse range of the rocket motor
  • Number before the hyphen (100) = average thrust (Newtons) of the rocket motor. Divide by 4.45 to get the average thrust in pounds
  • Number after the hyphen (5) = ejection charge delay time (seconds)
• Total impulse = average thrust x burn time
• Assuming that each motor has the full allowable impulse, how many "H" motors have the same total impulse as a single "J" motor? 4
• H64-8 rocket motor with an impulse of 320.00 N-s has an approximate burn time of: 5 seconds (burn time = total impulse / average thrust.   Using this formula,  320.00N-s / 64N = 5 seconds)
• What impulse class is a 690 N-s motor? J class motor (see table below)
• Test data for a motor shows an average thrust of 100N for 6 seconds. What impulse class is this motor? Total impulse = average thrust x burn time, so 100N x 6s = 600 N-s (I-class motor)

This table shows the impulse corresponding to different class motors. Every letter signifies a doubling of impulse. The ones highlighted in blue are the ones that the written exam references, so you should know these (or you could always just memorize the answers to the questions but it helps to know the table)

That's the end of my notes! Now that you've reviewed these notes, scroll up and click on the links to take the practice exams!