| 1. Which of Newton's Laws best describes the behavior of a rocket motor? |
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A- Newton's First Law: Every 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.
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| 2. How does Newton's Third Law 'To every action there is
always an equal and opposite reaction' relate to rocketry? |
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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.
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| 3. What are the three forces acting upon a rocket during the course
of its flight? |
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A- Thrust, rocket diameter and finish.
B- Nose cone shape, thrust and drag.
C- Gravity, thrust and aerodynamic drag.
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| 4. What are the major factors that determine the maximum altitude
of a high power rocket in vertical flight? |
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A-Lift-off weight, propellant weight and motor thrust.
B- Fin size, propellant weight and motor thrust.
C- Motor thrust, weight and aerodynamic drag.
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| 5. For an inherently stable rocket, what is the relationship of
center of gravity (CG) to the center of pressure (CP)? |
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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 be in front of the fins of a rocket.
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| 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 a stable rocket? |
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A- There is insufficient information to answer this question.
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.
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| 7. The center of pressure (CP) of a rocket is generally defined as: |
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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.
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| 8. What is the "rule-of-thumb" for a stable rocket? |
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A- That the center of gravity is one body diameter in front of the center of pressure.
B- That the center of gravity is at the same point as the center of pressure.
C- There is no rule-of-thumb because there are too many variables.
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| 9. When determining the center of gravity (CG) of a rocket with
a heavier motor at the launch site, one can: |
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A- Install the motor, recovery system and payload and determine
the balance point of the rocket as it is ready for flight.
B- Balance the rocket with an empty motor 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 more powerful motor because it has more thrust.
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| 10. What happens to the center of gravity (CG) of a rocket during
a solid rocket motor's thrusting phase? |
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A- The Center of gravity stays the same.
B- The Center of gravity shifts forward.
C- The center of gravity shifts aft.
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| 11. How can a statically unstable rocket be made stable? |
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A- Using a heavier motor.
B- Adding weight to the nose.
C- Making the rocket shorter.
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| 12. What are three methods used to shift the center of gravity
(CG) of a rocket forward? |
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A- Add weight to the nose, make the rocket longer, install larger 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.
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| 13. What are three methods used to shift the center of pressure (CP) aft? |
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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.
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| 14. What is the definition of coefficient of drag (Cd)? |
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A- A dimensionless number that represents the effect of gravity and Mach number of the rocket.
B- A dimensionless number representing the rocket configuration,
Mach number and angle of attack.
C- A dimensionless number that represents the friction of the
launcher and launch velocity.
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| 15. What happens to the coefficient of drag (Cd) as the rocket
approaches the speed of sound? |
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A- The Cd decreases.
B- The Cd stays the same.
C- The Cd increases.
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| 16. For a subsonic rocket, what major factors affect the coefficient of drag (Cd)? |
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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.
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| 17. What effect does a boat tail have on a subsonic rocket's coefficient of drag (Cd)? |
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A- No effect, a boat tail is only a cosmetic design feature.
B- It increases the Cd by changing the airflow over the fins.
C- It decreases the Cd by reducing the base drag.
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| 18. The flight of a high power rocket can be separated into three portions; they are: |
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A- Ignition, burnout and peak altitude.
B- Powered flight, un-powered ascent and peak altitude.
C- Powered flight, un-powered ascent and descent.
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| 19. What is the thrust curve of a regressive motor burn? |
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A- A regressive burn has a high initial thrust relative to the
ending thrust of the motor.
B- A regressive burn has a lower initial thrust relative to the ending thrust.
C- The thrust curve is flat.
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| 20. What is the thrust curve of a progressive motor? |
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A- A progressive burn has a high initial thrust relative to the
ending thrust of the motor.
B- A progressive burn has a lower initial thrust relative to the ending thrust.
C- The thrust curve is flat.
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| 21. Why does a Bates grain have an essentially neutral thrust curve? |
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A- Because core burning motors always have a regressive burn.
B- Because the burn area of the motor remains relatively constant.
C- Because the core in the motor grain has a uniform burn area over time.
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| 22. What is the function of a motor liner and the O-ring seals
in a solid rocket motor? |
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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.
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| 23. What is the most common oxidizer in commercially available
high power composite solid rocket motors? |
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A- Ammonium Perchlorate.
B- Ammonium Nitrate.
C- Ammonium Chlorate.
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| 24. What is NH4ClO4? |
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A- Ammonium Perchlorate.
B- Ammonium Nitrate.
C- Ammonium Chlorate.
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| 25. A small hole is typically recommended near the top, but below
the nosecone or payload section, of a high power rocket's booster section. Why? |
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A- This hole allows excessive ejection charge pressures to vent
to reduce shock cord stress.
B- The hole is used to give air pressure readings for on-board altimeters.
C- The hole vents internal air pressure as the rocket gains altitude
to prevent premature separation.
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| 26. What happens when changing to smaller or fewer injector orifices
in an ideal hybrid rocket motor (assume the oxidizer weight stays the same)? |
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A- The total impulse decreases and the average thrust increases.
B- The total impulse stays the same and the average thrust increases.
C- The total impulse stays the same and the average thrust decreases.
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| 27. What happens when changing to more or larger injector orifices
in an ideal hybrid rocket motor (assume the oxidizer weight stays the same)? |
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A- The total impulse decreases and the average thrust increases.
B- The total impulse stays the same and the average thrust increases.
C- The total impulse stays the same and the average thrust decreases.
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| 28. What is the oxidizer most commonly used in a commercial hybrid rocket motor? |
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A- N2O
B- N2O4
C- NO2
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| 29. What is the nominal tank pressure of a nitrous oxide hybrid
motor at 75°F? |
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A- 100 psi
B- 750 psi
C- 1500 psi
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| 30. Above what temperature does pressurized nitrous oxide change to a gas? |
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A- 97°F
B- 75°F
C- 37°F
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| 31. A rocket with a motor cluster consisting of a central composite
motor and four black powder motors using thermalite igniters or electric matches: |
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A- will result in all motors starting about the same time.
B- will result in the composite motor starting first followed
by the black powder motors.
C- will result in the black powder motors starting first followed
by the central composite motor.
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| 32. What typically happens to a marginally stable rocket with
a hybrid motor during the thrusting phase? |
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A- Nothing.
B- The rocket may become more stable.
C- The rocket may become less stable.
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| 33. In general terms, the specific impulse of a rocket motor is: |
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A- The total thrust force of a motor throughout its action time.
B- The total impulse divided by unit weight of propellant.
C- Dependent on the diameter and length of the propellant grain.
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| 34. In general terms, the total impulse of a rocket motor can
be described as: |
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A- The product of the average motor thrust and its burn time.
B- The product of the propellant weight and its burn time.
C- The product of the propellant weight and the motor thrust.
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| 35. The average thrust of a rocket motor is 100 Newtons and the
burn time is 4 seconds, what is the total impulse? |
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A- 25 Newton-seconds
B- 400 Newton-seconds
C- 400 Newtons
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| 36. Which motor has a higher total impulse? |
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A- J200
B- J400
C- K200
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| 37. Which motor has a higher average thrust? |
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A- J200
B- J400
C- K200
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| 38. What is the difference between a J640 and a J320 high power
rocket motor (assume full 1280 Newton-second J motors)? |
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A- The J320 burns out twice as fast as the J640.
B- There is no difference between the motors, the numbers are
manufacturer reference only.
C- The J640 burns out twice as fast as the J320.
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| 39. Which of the following has a total impulse in the J motor range? |
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A- It = 600 Newton-seconds
B- It = 1000 Newton-seconds
C- It = 1290 Newton-seconds
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| 40. What is a Newton? |
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A- The amount of force required to accelerate one pound one foot
per second per second.
B- The amount of force required to accelerate one kg, one foot
per second per second.
C- The amount of force required to accelerate one kg, one meter
per second per second.
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| 41. What does the motor designation I220-8 mean? |
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A- The motor is in the I impulse range with an average thrust
of 220 Newtons and an 8 second delay from motor ignition.
B- The motor is in the I impulse range, having a total impulse
of 620 Newton-seconds with an average thrust of 220 Newtons and
an 8 second delay from motor burn-out.
C- The motor is in the I impulse range with an average thrust
of 220 Newtons and an 8 second ejection delay from motor burn-out.
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| 42. What is the difference in kinetic energy between two identical
rockets, one descending at 30 feet per second, the other descending at 60 feet per second? |
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A- Cannot be determined without the weight.
B- Two times as much energy.
C- Four times as much energy.
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| 43. The equation for determining the energy of a moving body (such
as a rocket) is: |
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A- E = 1/2 mv2
B- E = ma2
C- E = mv3
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| 44. What is the purpose of a launch rod, rail or tower? |
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A- To keep the rocket pointing in the right direction prior to flight.
B- To control the rocket's flight long enough to allow aerodynamic stability.
C- Both a and b.
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| 45. What is the purpose of a launch lug? |
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A- To add drag to the rocket at launch.
B- To guide the rocket along the launch rod or rail.
C- Both a and b.
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| 46. A rocket with a motor cluster consisting of a central composite
54mm J415 motor and four 29mm G80 composite motors using thermalite
igniters or electric matches: |
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A- will result in all motors starting about the same time.
B- will result in the J415 motor starting first followed by the G80's.
C- will result in the G80's starting first followed by the J415.
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| 47. What can happen if all the motors of a cluster do not ignite at launch? |
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A- Nothing, the rocket is inherently stable.
B- The rocket may not fly straight.
C- The rocket will shred.
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| 48. What is a shred? |
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A- A failure of the rocket air frame during boost resulting in destruction of the rocket.
B- A failure of the recovery system during boost.
C- A failure of the motor causing early ejection.
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| 49. What is a cato? |
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A- A failure of the rocket resulting in failure of the air frame during boost.
B- A failure of the recovery system during boost.
C- A failure of the motor causing flight termination.
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| 50. What is the primary requirement for a rocket motor ignitor? |
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A- It must transfer sufficient heat to the propellant to assure ignition.
B- It must produce hot, high velocity gasses to assure ignition.
C- It must have a high resistance to be reliable.
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