Tra - Level 2 CERT - Tech And Safety

108 Questions | Total Attempts: 104

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Technology Quizzes & Trivia

Working on my Level 2 cert for TRA


Questions and Answers
  • 1. 
    Which of newton’s laws best describes the behavior of a rocket motor
    • A. 

      Newton’s first law: A body continues in its state of rest or of uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it,

    • B. 

      Newton’s second law: The rate of change of momentum is proportional to the force impressed and is in the same direction as that force.

    • C. 

      Newton’s third law: To every action there is always an equal and opposite reaction.

  • 2. 
    How does Newton’s third law “to every action there is always an equal and opposite reaction” relate to rocketry?
    • A. 

      That the blast deflector must be strong enough to push the rocket off the launch pad at ignition

    • B. 

      That a rocket flies because the rocket motor “pushes” the rocket in a direction opposite of the exhaust jet

    • C. 

      That the thrust of a rocket motor is proportional to the air density at the launch site

  • 3. 
    What are the three forces action upon a rocket during the course of its flight?
    • A. 

      Thrust, Rocket Diameter and finish

    • B. 

      Nose cone shape, thrust and drag

    • C. 

      Gravity, thrust and aerodynamic drag

  • 4. 
    What are the three major factors that determine the maximum altitude of a high power rocket in vertical flight
    • A. 

      Lift-off weight, propellant weight and motor thrust

    • B. 

      Fin size, propellant weight and motor thrust

    • C. 

      Motor thrust, weight and aerodynamic drag

  • 5. 
    For an inherently stable rocket, which statement about the center of gravity (CG) four inches behind the center of pressure (CP). Is this a rocket likely to be stable?
    • A. 

      The CG must be behind the CP relative to the desired direction of flight

    • B. 

      The CG must be forward of the CP relative to the desired direction of flight

    • C. 

      The CG must move forward (in the desired direction of flight) during the motor burn

  • 6. 
    A 4” diameter rocket with its motor is determined to have the center of gravity (CG) four inches behind the center of pressure (CP). Is this rocket likely to be stable?
    • A. 

      No, the CG should be at least two body diameters behind the CP

    • B. 

      No, the CP must be behind the CG for the rocket to be stable

    • C. 

      Yes, the CP is one body diameter in front of the CG

  • 7. 
    The center of pressure (CP) of a rocket is generally defined as:
    • A. 

      The balance point of the rocket without the motor

    • B. 

      The total area of the fins, airframe and nose cone divided by two

    • C. 

      The point at which aerodynamic lift on a rocket is centered

  • 8. 
    What is the “rule-of-thumb” for a stable rocket?
    • A. 

      That the center of gravity should be at least one body diameter in front of the center of pressure

    • B. 

      That the center of gravity should be very nearly at the same point as the center of pressure

    • C. 

      The rocket should balance near or at the center of gravity

  • 9. 
    You are at the launch site and decide to fly your rocket on a heavier motor than you simulated it on. Which statement regarding CG is true?
    • A. 

      One can install a motor, recovery system and payload and determine the balance point of the rocket as it is ready for flight.

    • B. 

      One can balance the rocket with the motor hardware alone because that is the condition of the rocket after motor burnout

    • C. 

      It is not necessary to test for the center of gravity when using a heavier motor because it has more thrust

  • 10. 
    What ordinarily happens to the center of gravity (CG) of a rocket during a solid rocket motor’s thrusting phase?
    • A. 

      The CG stays the same

    • B. 

      The CG shifts forward

    • C. 

      The CG shifts aft

  • 11. 
    How can a statically unstable rocket be made stable?
    • A. 

      Using a heavier motor

    • B. 

      Adding weight to the nose

    • C. 

      Making the rocket shorter

  • 12. 
    What are three methods used to shift center of gravity (CG) of a rocket forward?
    • A. 

      Add weight to the nose, make the rocket longer, install the number of fins

    • B. 

      Add weight to the nose, make the rocket longer, use a smaller (or lighter) motor

    • C. 

      Add weight to the nose, make the rocket shorter, use a smaller motor

  • 13. 
    What are three methods used to shift the center of pressure (CP) aft?
    • A. 

      Make the rocket shorter, use larger fins, increase the number of fins

    • B. 

      Make the rocket shorter, use smaller fins, add weight to the nose

    • C. 

      Make the rocket shorter, change the number of fins, use a longer launch rod

  • 14. 
    The definition of coefficient of drag (Cd) is:
    • A. 

      A dimensionless number that represents the effect of gravity and Mach number of the rocket

    • B. 

      A dimensionless number dependent on the rocket configuration, Mach number and angle of attack

    • C. 

      The force, in newton’s, exerted on the rocket by the atmosphere

  • 15. 
    What happens to the coefficient of drag (Cd) as the rocket approaches the speed of sound?
    • A. 

      The Cd decreases

    • B. 

      The Cd stays the same

    • C. 

      The Cd increases

  • 16. 
    For a subsonic rocket, what factors most greatly affect the coefficient of drag (Cd)?
    • A. 

      Motor thrust, body diameter, nosecone shape and fin shape

    • B. 

      Speed, airframe dimensions, nosecone shape and fin shape

    • C. 

      Gravity, airframe dimensions, nosecone shape and fin shape

  • 17. 
    What effect does a boat tail have on a subsonic rocket’s coefficient of drag (Cd)?
    • A. 

      No effect, a boat tail is only a cosmetic design feature

    • B. 

      It incrases the Cd by changing the airflow over the fins

    • C. 

      It decreases the Cd by reducing the base drag

  • 18. 
    The flight of a high power rocket can be separated into three portions; they are:
    • A. 

      Ignition, burnout and peak altitude

    • B. 

      Powered flight, un-powered ascent and peak altitude

    • C. 

      Powered flight, un-powered ascent and descent

  • 19. 
    Which describes the thrust curve of a regressive motor burn?
    • A. 

      A high initial thrust relative to the ending thrust of the motor

    • B. 

      A lower initial thrust relative to the ending thrust

    • C. 

      The thrust curve is flat

  • 20. 
    Which describes the thrust curve of a progressive motor?
    • A. 

      A general decrease in thrust during the burn

    • B. 

      A general increase in thrust during the burn

    • C. 

      About the same thrust at ignition as at burnout

  • 21. 
    A bates grain has an essentially neutral thrust curve because:
    • A. 

      Core burning motors always have a neutral

    • B. 

      The area of burning propellant remains relatively constant

    • C. 

      The core is centered in the propellant grain

  • 22. 
    What is the function of the motor liner and the O-ring seals in a solid rocket motor?
    • A. 

      To hold all of the parts in place prior to ignition of the rocket motor

    • B. 

      To make the motor easier to clean if it is a reloadable motor

    • C. 

      To keep the hot gasses of the motor from burning or melting the motor case

  • 23. 
    What is the most common oxidizer in commercially available high power composite solid rocket motors?
    • A. 

      Ammonium Perchlorate

    • B. 

      Ammonium Nitrate

    • C. 

      Ammonium Chlorate

  • 24. 
    What is NH4ClO4?
    • A. 

      Ammonium Perchlorate

    • B. 

      Ammonium Nitrate

    • C. 

      Ammonium Chlorate

  • 25. 
    A small hole is typically drilled near the top of a high power rockets airframe, below the nose cone or payload section. Why?
    • A. 

      This hole vents excessive ejection charge pressure, reducing shock cord stress

    • B. 

      The hole permits on-board altimeter to obtain air pressure readings

    • C. 

      The hole vents internal air pressure as the rocket gains altitude to prevent premature separation

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