L2 HPR Technical Quiz – NSW Rocketry Association

#1. A rocket with a motor cluster consisting of a central composite motor and four black powder motors, using five identical igniters:

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

#2. 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 the 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

#3. Rocket A weighs twice as much as rocket B. Both are descending at 20 feet per second. Which statement is true?

a.The two rockets have the same kinetic energy

b.Rocket A has two times the kinetic energy of rocket B

c.Rocket A has four times the kinetic energy of rocket B

#4. How do you convert Newtons of thrust to pounds of thrust?

a.Add 4.45 to the number of Newtons

b.Multiply Newtons by 4.45

c.Divide Newtons by 4.45

#5. What can happen if all the motors of a cluster do not ignite at launch?

a.Nothing, if the rocket is inherently stable

b.The rocket may not fly straight

c.The rocket will shred

#6. 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

#7. In general terms, the specific impulse of a rocket motor is:

a.The total thrust force of a motor throughout its action time

b.The total impulse divided by a unit weight of propellant

c.Inversely related to the diameter and length of the propellant grain

#8. What is a Newton?

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

#9. Which of the following is most likely in dual-deployment rockets that use a drogue and a main parachute?

a.The drogue and the main can tangle if not properly arranged

b.The drogue slows the rocket too much and it drifts too far

c.The drogue does not slow the rocket enough and it lands hard

#10. What is the oxidizer most commonly used in a commercial hybrid rocket motor?

a.N2O

b.N2O4

c.NO2

#11. 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

#12. What is NH4ClO4?

a.Ammonium Perchlorate

b.Ammonium Nitrate

c.Ammonium Chlorate

#13. For a rocket with a much less than 10:1 “length to diameter” (L/D) ratio, such as spools and pyramids, what type of drag contributes significantly to stability and makes it possible to fly without much, if any, nose weight?

a.Nose drag

b.Base drag

c.Surface drag

#14. 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

#15. Which of the motors listed below has the highest total impulse?

a.J200

b.J400

c.K200

#16. 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

#17. 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, rocket weight, and aerodynamic drag

#18. 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

#19. What is a shred?

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

#20. When using a pressure-sensor altimeter in a rocket that will not reach Mach 1:

a.One or more access holes must be drilled at the base of the nose cone to permit access to the atmosphere during flight

b.A timer, but not a motor delay, may be used as backup for deployment

c.One or more holes must be drilled in the electronics bay for atmospheric access

#21. What is the difference between a J640 and a J320 high power rocket motor (assume full 1280 Newton-second J motors)?

a.There is no difference between the motors, the numbers are manufacturer reference only

b.The J320 burns out twice as fast as the J640

c.The J640 burns out twice as fast as the J320

#22. Which of the motors listed below has the highest average thrust?

a.J200

b.J400

c.K200

#23. What typically happens to a marginally stable rocket with a hybrid motor during the thrusting phase?

a.Nothing

b.The rocket may become more stable

c.The rocket may become less stable

#24. What is the primary requirement for a rocket motor ignitor?

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

#25. 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

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