Tra - Level 2 CERT - Tech And Safety
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How does Newton’s third law “to every action there is always an equal and opposite reaction” relate to rocketry?
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That the blast deflector must be strong enough to push the rocket off the launch pad at ignition
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That a rocket flies because the rocket motor “pushes” the rocket in a direction opposite of the exhaust jet
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That the thrust of a rocket motor is proportional to the air density at the launch site
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This TRA Level 2 Certification quiz focuses on the technical aspects and safety measures in rocketry, assessing understanding of Newton's laws, rocket stability, and forces affecting a rocket's flight. It is designed for enthusiasts and professionals aiming to enhance their expertise in high-power rocketry.
Quiz Preview
- 2.
The center of pressure (CP) of a rocket is generally defined as:
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The balance point of the rocket without the motor
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The total area of the fins, airframe and nose cone divided by two
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The point at which aerodynamic lift on a rocket is centered
Correct Answer
A. The point at which aerodynamic lift on a rocket is centeredExplanation
The center of pressure (CP) is the point on the rocket where the aerodynamic lift is centered. This means that aerodynamic lift, if the rocket is at a non-sero angle of attack, forward of this point is balanced by the aerodynamic lift aft of this point.Rate this question:
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- 3.
How can a statically unstable rocket be made stable?
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Using a heavier motor
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Adding weight to the nose
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Making the rocket shorter
Correct Answer
A. Adding weight to the noseExplanation
Adding enough weight to the nose will shift the center of gravity (CG) forward of the center of pressure (CP).Rate this question:
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- 4.
What are three methods used to shift center of gravity (CG) of a rocket forward?
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Add weight to the nose, make the rocket longer, install the number of fins
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Add weight to the nose, make the rocket longer, use a smaller (or lighter) motor
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Add weight to the nose, make the rocket shorter, use a smaller motor
Correct Answer
A. Add weight to the nose, make the rocket longer, use a smaller (or lighter) motorExplanation
Moving the CG forward requires judicious design changes. The following are given as "rules of thumb": Adding weight to the nose moves the CG forward by counterbalancing the rocket. Think of the rocket as a lever; making the rocket longer shifts the CG forward by making the lever longer. Using a smaller (or lighter) motor reduces the weight aft thus shifting the CG forward.Rate this question:
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- 5.
What happens to the coefficient of drag (Cd) as the rocket approaches the speed of sound?
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The Cd decreases
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The Cd stays the same
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The Cd increases
Correct Answer
A. The Cd increasesExplanation
As the rocket approaches the speed of sound, the coefficient of drag (Cd) increases. This is because at high speeds, the air resistance on the rocket becomes more significant, causing an increase in drag. The Cd is a measure of the aerodynamic efficiency of an object, and as the speed increases, the Cd value also increases. This means that the rocket experiences more air resistance and requires more force to overcome it, making it less efficient in terms of aerodynamics.Rate this question:
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- 6.
The flight of a high power rocket can be separated into three portions; they are:
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Ignition, burnout and peak altitude
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Powered flight, un-powered ascent and peak altitude
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Powered flight, un-powered ascent and descent
Correct Answer
A. Powered flight, un-powered ascent and descentExplanation
The correct answer is "Powered flight, un-powered ascent and descent". This explanation is based on the understanding of how a high power rocket operates during its flight. During the powered flight phase, the rocket's engines are ignited and provide thrust to propel the rocket upward. Once the engines burn out, the rocket continues to ascend due to its momentum, entering the un-powered ascent phase. Finally, during the descent phase, the rocket descends back to the ground without any active propulsion. Therefore, the flight of a high power rocket can be divided into these three portions.Rate this question:
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- 7.
What is the function of the motor liner and the O-ring seals in a solid rocket motor?
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To hold all of the parts in place prior to ignition of the rocket motor
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To make the motor easier to clean if it is a reloadable motor
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To keep the hot gasses of the motor from burning or melting the motor case
Correct Answer
A. To keep the hot gasses of the motor from burning or melting the motor caseExplanation
The function of the motor liner and the O-ring seals in a solid rocket motor is to keep the hot gases of the motor from burning or melting the motor case. These components act as a barrier, preventing the intense heat and pressure generated during ignition from damaging the structural integrity of the motor case. Without the motor liner and O-ring seals, the motor case would be susceptible to burning or melting, which could lead to catastrophic failure of the rocket motor.Rate this question:
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- 8.
What can happen is all the motors of a cluster do not ignite at launch?
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Nothing the rocket is inherently stable
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The rocket may not fly straight
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The rocket will shred
Correct Answer
A. The rocket may not fly straightExplanation
If all the motors of a cluster do not ignite at launch, it can cause the rocket to lose balance and stability. Without the thrust from all motors, the rocket may veer off course and deviate from its intended flight path. This can result in an unstable and unpredictable trajectory, causing the rocket to not fly straight.Rate this question:
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- 9.
What is a shred?
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A failure of the rocket air frame during boost resulting in destruction of the rocket
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A failure of the recovery system during boost
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A failure of the motor causing early ejection
Correct Answer
A. A failure of the rocket air frame during boost resulting in destruction of the rocketExplanation
The correct answer is a failure of the rocket air frame during boost resulting in destruction of the rocket. This means that a shred refers to the breaking or tearing apart of the rocket's air frame while it is in the process of boosting. This failure is severe enough to cause the complete destruction of the rocket. It could be due to structural weaknesses, excessive forces, or other factors that cause the rocket's structure to fail under the stress of the boost phase.Rate this question:
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- 10.
What is a cato?
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A failure of the rocket resulting in failure of the airframe during boost
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A failure of the recovery system during boost
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A failure of the motor causing flight termination
Correct Answer
A. A failure of the motor causing flight terminationExplanation
The correct answer is a failure of the motor causing flight termination. This means that a cato refers to a failure of the rocket motor, which leads to the termination of the flight. It suggests that the motor malfunctioned or experienced a catastrophic failure, causing the rocket to stop functioning and the flight to be terminated.Rate this question:
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- 11.
What is the primary requirement for the rocket motor ignitor?
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It must transfer Sufficient heat to the propellant to assure ignition
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It must produce hot, high velocity gasses to assure ignition
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It must have a high resistance to be reliable
Correct Answer
A. It must transfer Sufficient heat to the propellant to assure ignitionExplanation
The primary requirement for the rocket motor ignitor is to transfer sufficient heat to the propellant to assure ignition. This is because the ignitor needs to generate enough heat to initiate the combustion process in the propellant, which in turn creates the necessary thrust for the rocket to take off. Without sufficient heat transfer, the propellant may not ignite properly, leading to a failed launch.Rate this question:
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- 12.
What is the major obstacle in most duel-deployment rockets that use a drogue and a main parachute?
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The drogue and the main can easily tangle if not properly arranged
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The drogue slows the rocket too much and it drifts too far
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The drogue does not slow the rocket enough and it lands hard
Correct Answer
A. The drogue and the main can easily tangle if not properly arrangedExplanation
In most duel-deployment rockets that use a drogue and a main parachute, the major obstacle is the possibility of the drogue and the main parachute getting tangled if they are not properly arranged. This can lead to complications and failures during the descent and landing of the rocket.Rate this question:
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- 13.
What is the major issue with accelerometer-based altimeters?
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They are larger, and usually much more expensive, the pressure-sensor altimeters
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They do not have multiple capabilities such as duel deployment, ignition of airstarts, etc
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The may not deploy properly if the flight is significantly non-vertical
Correct Answer
A. The may not deploy properly if the flight is significantly non-verticalExplanation
Accelerometer-based altimeters rely on measuring acceleration to determine altitude. However, they may not deploy properly if the flight is significantly non-vertical, meaning if the flight path deviates from a straight vertical ascent or descent. This is because the accelerometer may not accurately measure the changes in altitude when the flight path is not vertical, leading to potential issues with the deployment of the altimeter.Rate this question:
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- 14.
The design and construction of high power rocket motors, high power rocket vehicles and launch operations is detailed in what code?
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NFPA 1122 and the Tripoli Safety Code
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NFPA 1125 and the Tripoli Safety Code
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NFPA 1127 and the Tripoli Safety Code
Correct Answer
A. NFPA 1127 and the Tripoli Safety CodeExplanation
The correct answer is NFPA 1127 and the Tripoli Safety Code. NFPA 1127 is a code that specifically addresses the design and construction of high power rocket motors, high power rocket vehicles, and launch operations. The Tripoli Safety Code is another set of guidelines and regulations that focus on safety in high power rocketry. Both of these codes provide comprehensive information and standards for ensuring the safe design, construction, and operation of high power rockets.Rate this question:
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- 15.
What is the Authority Having Jurisdiction?
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A court proceeding that rules on high power rocketry activities
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The individual preparing a high power rocket for flight
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The organization, office or individual responsible for approving equipment, an installation or procedure
Correct Answer
A. The organization, office or individual responsible for approving equipment, an installation or procedureExplanation
The Authority Having Jurisdiction refers to the organization, office, or individual who has the responsibility and power to approve equipment, installations, or procedures. They have the authority to make decisions and ensure that everything complies with the relevant regulations and standards. This could include approving the use of certain equipment, granting permits for installations, or validating procedures to ensure safety and compliance.Rate this question:
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- 16.
What is a complex high power rocket?
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A rocket having more than one stage
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A rocket having a cluster of rocket motors
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Either a or b
Correct Answer
A. Either a or bExplanation
A complex high power rocket refers to a rocket that either has more than one stage or a cluster of rocket motors. This means that it can have multiple sections or engines that work together to achieve high power and altitude. The rocket can be complex in terms of its design and functionality, requiring advanced engineering and technology.Rate this question:
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- 17.
What is a high power rocket motor?
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A rocket motor with more than 80 Newton-seconds of total impulse and 80 Newtons average thrust
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A rocket motor with more than 160 Newton-seconds of total impulse or 80 Newtons average thrust
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A rocket motor with more than 160 Newton-seconds of total impulse and 160 Newtons average thrust
Correct Answer
A. A rocket motor with more than 160 Newton-seconds of total impulse or 80 Newtons average thrustExplanation
A high power rocket motor is defined as a rocket motor with more than 160 Newton-seconds of total impulse or 80 Newtons average thrust. This means that it either has a total impulse greater than 160 Newton-seconds or an average thrust greater than 80 Newtons.Rate this question:
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- 18.
Who may operate a high power rocket?
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Any member of a nationally recognized rocketry organization
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Only those licensed by the federal government
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A person that is a certified user
Correct Answer
A. A person that is a certified userExplanation
A person that is a certified user may operate a high power rocket. This implies that individuals who have undergone a certification process and have been deemed qualified and knowledgeable enough to handle high power rockets are allowed to operate them. This requirement ensures that only individuals with the necessary skills and understanding of safety protocols are permitted to operate these potentially dangerous devices.Rate this question:
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- 19.
What criteria apply to the construction of a high power Rocket?
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Use suitable materials to withstand operating structural stresses and retain integrity in flight
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Use only the lightest weight materials for the construction of high power rockets
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Use materials that allow minimal flex of the rocket in flight
Correct Answer
A. Use suitable materials to withstand operating structural stresses and retain integrity in flightExplanation
The construction of a high power rocket requires the use of suitable materials that can withstand the structural stresses and maintain integrity during flight. This is important because rockets are subjected to high forces and vibrations during launch and ascent. Using materials that are strong and durable ensures that the rocket can withstand these stresses without breaking or collapsing. Additionally, the materials should be able to retain their integrity in flight, meaning they should not degrade or weaken due to factors like temperature changes or exposure to atmospheric conditions.Rate this question:
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- 20.
When is it permissible to catch a high power rocket?
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If the rocket weighs less than 2.2 pounds or 1kg
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It is never permissible to catch a high power rocket
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If the rocket is falling slowly enough that it is deemed not the be a hazard
Correct Answer
A. It is never permissible to catch a high power rocketExplanation
Catching a high power rocket is never permissible because it can be dangerous and pose a risk to the person attempting to catch it. Rockets can reach high speeds and have the potential to cause serious injury or damage upon impact. It is safer to let the rocket fall to the ground or use other methods, such as a parachute or recovery system, to safely retrieve it.Rate this question:
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- 21.
What payloads are not permitted in a high power rocket?
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Payloads that are flammable or explosive or intended to cause harm
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Vertebrate animals
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Both a and b
Correct Answer
A. Both a and bExplanation
Both a and b are not permitted as payloads in a high power rocket. This is because payloads that are flammable, explosive, or intended to cause harm pose a significant risk to the rocket and the surrounding environment. Similarly, vertebrate animals are not allowed as payloads due to ethical considerations and the potential harm they may experience during the rocket launch. Therefore, both a and b are not permitted in a high power rocket.Rate this question:
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- 22.
When shall the motor ignitor(s) be installed in a high power rocket motor?
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At the launcher or a designated area
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When the motor is installed in the rocket
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Neither a nor b
Correct Answer
A. At the launcher or a designated areaExplanation
The motor ignitor(s) should be installed at the launcher or a designated area. This is because installing the ignitor(s) before the motor is installed in the rocket could pose a safety risk, as it may accidentally ignite during transportation or handling. Therefore, it is important to wait until the motor is securely in place at the launcher or designated area before installing the ignitor(s) to ensure safe and controlled ignition of the rocket motor.Rate this question:
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- 23.
What is the maximum altitude allowed for flying high power rockets if there is a cloud ceiling of 3000 feet?
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3500 feet
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To the limited of the FAA waiver
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Neither a nor b
Correct Answer
A. Neither a nor bExplanation
The correct answer is "Neither a nor b". This means that the maximum altitude allowed for flying high power rockets is not 3500 feet, nor is it limited to the FAA waiver. The question implies that the cloud ceiling is at 3000 feet, but it does not provide any information about the maximum altitude allowed. Therefore, we cannot determine the correct answer based on the given information.Rate this question:
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- 24.
When may a solid propellant high power rocket motor be shipped and stored with the ignitor installed?
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It is never permissible to ship or store a solid propellant high power rocket motor with the ignitor is place
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When the rocket will be launched within 48 hours of ignitor installation
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Neither a nor b
Correct Answer
A. It is never permissible to ship or store a solid propellant high power rocket motor with the ignitor is placeExplanation
A solid propellant high power rocket motor should never be shipped or stored with the ignitor installed. This is because having the ignitor in place increases the risk of accidental ignition or premature firing, which can be extremely dangerous. Therefore, it is always necessary to remove the ignitor before shipping or storing the rocket motor.Rate this question:
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- 25.
Who may receive a solid propellant high power rocket motor?
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A certified user
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Any member of a nationally recognized rocketry organization
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Any person over the age of 18
Correct Answer
A. A certified userExplanation
A certified user may receive a solid propellant high power rocket motor because they have undergone specific training and certification to handle and operate such equipment safely. This ensures that they have the necessary knowledge and skills to handle the potential risks associated with high power rocket motors.Rate this question:
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- 26.
When is it permissible to consume alcohol when prepping or launching high power rockets?
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When the preparation is done the day before the launch
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If the blood alcohol level is below the “impaired” level
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It is never permitted
Correct Answer
A. It is never permittedExplanation
Consuming alcohol when prepping or launching high power rockets is never permitted due to the potential risks and dangers involved. Alcohol impairs judgment, coordination, and reaction time, which can lead to accidents and mishaps during the preparation or launch process. Safety is of utmost importance in rocketry, and any form of impairment, including alcohol consumption, is strictly prohibited to ensure the well-being of individuals and the success of the mission.Rate this question:
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- 27.
What organizations may currently certify users of high power rocket motors include:
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Tripoli Rocketry Association (TRA) and the National Association of Rocketry (NAR) only
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The Bureau of Alcohol, Tobacco, Firearms, and Explosives (BATFE)
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TRA, NRA the Canadian Association of Rocketry (CAR) and the United Kingdom Rocketry Association (UKRA)
Correct Answer
A. TRA, NRA the Canadian Association of Rocketry (CAR) and the United Kingdom Rocketry Association (UKRA) -
- 28.
For a subsonic rocket, what factors most greatly affect the coefficient of drag (Cd)?
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Motor thrust, body diameter, nosecone shape and fin shape
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Speed, airframe dimensions, nosecone shape and fin shape
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Gravity, airframe dimensions, nosecone shape and fin shape
Correct Answer
A. Speed, airframe dimensions, nosecone shape and fin shapeExplanation
The coefficient of drag (Cd) is a measure of the resistance an object experiences as it moves through a fluid, in this case, air. In the context of a subsonic rocket, the factors that most greatly affect Cd are speed, airframe dimensions, nosecone shape, and fin shape. Speed affects Cd because as the rocket moves faster, the air resistance increases. Airframe dimensions, nosecone shape, and fin shape also impact Cd as they determine the overall shape and surface area of the rocket, which affects how the air flows around it.Rate this question:
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- 29.
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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25 Newton-seconds
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400 Newton-seconds
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400 Newtons
Correct Answer
A. 400 Newton-secondsExplanation
The total impulse of a rocket motor can be calculated by multiplying the average thrust by the burn time. In this case, the average thrust is given as 100 Newtons and the burn time is 4 seconds. Therefore, the total impulse can be calculated as 100 Newtons * 4 seconds = 400 Newton-seconds.Rate this question:
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- 30.
Rocket A weighs twice as much as rocket B. Both are descending at 20 feet per second. Which statement is true?
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The two rockets have the same kinetic energy
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Rocket A has twice the kinetic energy of rocket B.
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Rocket A has four times the kinetic energy of rocket A
Correct Answer
A. Rocket A has twice the kinetic energy of rocket B.Explanation
The kinetic energy of an object is given by the equation KE = 0.5 * m * v^2, where m is the mass of the object and v is its velocity. In this case, Rocket A weighs twice as much as Rocket B, so its mass is twice that of Rocket B. Since both rockets are descending at the same velocity, the velocity term in the equation is the same for both rockets. Therefore, Rocket A has twice the mass of Rocket B, resulting in twice the kinetic energy.Rate this question:
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- 31.
For a cluster rocket, which construction technique will minimize the effect of one motor failing to ignite?
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Make the holes in the forward centering ring slightly closer to the rocket’s centerline than those of the aft centering right
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Space the centering rings precisely one motor length apart
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Use four smaller fins instead of three larger fins
Correct Answer
A. Make the holes in the forward centering ring slightly closer to the rocket’s centerline than those of the aft centering rightExplanation
By making the holes in the forward centering ring slightly closer to the rocket's centerline than those of the aft centering ring, the effect of one motor failing to ignite can be minimized. This construction technique ensures that the rocket's balance and stability are maintained even if one motor fails to ignite. By shifting the center of gravity slightly towards the centerline, the rocket will be less likely to veer off course or become unstable in the event of a motor failure.Rate this question:
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- 32.
When is a recovery device not necessary in a high power rocket?
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When the high power rocket is intended for ballistic flight
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When the rocket has a bursting charge
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A recovery device is always necessary
Correct Answer
A. A recovery device is always necessaryExplanation
A recovery device is always necessary because it helps to bring the rocket safely back to the ground after launch. Without a recovery device, the rocket would continue to ascend and eventually crash back to the ground, causing damage and potentially injuring people or property. Therefore, regardless of whether the rocket is intended for ballistic flight or has a bursting charge, a recovery device is essential for a safe and controlled descent.Rate this question:
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- 33.
A high power rocket may be constructed of what materials?
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Paper, wood, fiberglass or plastic with a minimum amount of metallic parts
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Paper, wood fiberglass, plastic and aluminum
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There are no restrictions on construction materials
Correct Answer
A. Paper, wood, fiberglass or plastic with a minimum amount of metallic partsExplanation
A high power rocket may be constructed of materials such as paper, wood, fiberglass, or plastic with a minimum amount of metallic parts. This is because these materials are lightweight and can withstand the high pressures and forces experienced during rocket flight. Metallic parts are generally avoided to reduce weight and increase overall performance.Rate this question:
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- 34.
What operating clearances must be complied with for flying high power rockets?
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NFPA 1122, NFPA 1127 and Federal Aviation Administration Regulation Part 101
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NFPA 1127, Federal Aviation Administration Regulation Part 101 and applicable federal, state and local regulations
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NFPA 1122, Federal Aviation Administration Regulation Part 101 and applicable federal, state and local regulations
Correct Answer
A. NFPA 1127, Federal Aviation Administration Regulation Part 101 and applicable federal, state and local regulationsExplanation
The correct answer is NFPA 1127, Federal Aviation Administration Regulation Part 101 and applicable federal, state and local regulations. This answer states that for flying high power rockets, one must comply with NFPA 1127, which is the National Fire Protection Association standard for high power rocketry. Additionally, compliance with Federal Aviation Administration Regulation Part 101 is required, as well as any relevant federal, state, and local regulations. These regulations ensure safety and proper operation of high power rockets.Rate this question:
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- 35.
When must the stability of a rocket be determined?
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If the safety monitor requires it
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Whenever the rocket is prepared for flight
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Both a and b
Correct Answer
A. Both a and bExplanation
The stability of a rocket must be determined both when the safety monitor requires it and whenever the rocket is prepared for flight. This is because ensuring the stability of the rocket is crucial for a safe and successful launch. The safety monitor may have specific requirements or guidelines that need to be followed to guarantee the rocket's stability. Additionally, it is essential to assess the stability of the rocket before every flight to account for any changes or adjustments made during the preparation process. Therefore, determining the stability of a rocket is necessary in both scenarios mentioned.Rate this question:
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- 36.
What are the elements of an ignition system?
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Remotely controlled, electrically operated, a launch switch that returns to OFF when released
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Remotely controlled, electrically operated and a removable safety interlock in series with the launch switch
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Remotely controlled, electrically operated, a launch system that returns to OFF when released and a removable safety interlock in series with the launch switch
Correct Answer
A. Remotely controlled, electrically operated, a launch system that returns to OFF when released and a removable safety interlock in series with the launch switchExplanation
The elements of an ignition system include a remotely controlled, electrically operated launch system that returns to OFF when released and a removable safety interlock in series with the launch switch. These components work together to ensure the safe and controlled operation of the ignition system. The remote control allows for convenient operation from a distance, while the electrical operation ensures efficient and reliable ignition. The launch system returning to OFF when released helps prevent accidental or unintended ignition, and the removable safety interlock adds an extra layer of protection by requiring the interlock to be removed before the ignition system can be activated.Rate this question:
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- 37.
When may a high power rocket be launched?
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After warning the spectators and giving a 5 second countdown
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When all systems are ready and after a 5 second countdown
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After informing and getting permission and attention from the safety monitor
Correct Answer
A. After informing and getting permission and attention from the safety monitorExplanation
A high power rocket may be launched after informing and getting permission and attention from the safety monitor. This is important to ensure that all necessary precautions have been taken and that the launch can be conducted safely. The safety monitor is responsible for overseeing the launch and ensuring that all systems are ready and that the spectators have been warned. The 5 second countdown is likely included to provide a final warning before the rocket is launched.Rate this question:
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- 38.
What is the minimum distance for smoking (or open flames) from a high power rocket motors, motor reloading kits, and pyrotechnic modules?
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10 feet
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25 feet
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There is no minimum distance
Correct Answer
A. 25 feetExplanation
The correct answer is 25 feet. This is the minimum distance required for smoking or open flames to be kept away from high power rocket motors, motor reloading kits, and pyrotechnic modules. This distance is important to ensure safety and prevent any potential accidents or fires.Rate this question:
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- 39.
What document has been adopted by the Tripoli Rocketry Association as The Tripoli Safety Code?
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NFPA 1127
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NFPA 1125
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NFPA 1122
Correct Answer
A. NFPA 1127Explanation
The Tripoli Rocketry Association has adopted NFPA 1127 as The Tripoli Safety Code.Rate this question:
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- 40.
Which of newton’s laws best describes the behavior of a rocket motor
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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,
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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.
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Newton’s third law: To every action there is always an equal and opposite reaction.
Correct Answer
A. Newton’s third law: To every action there is always an equal and opposite reaction.Explanation
Newton's third law. Applying force in one direction always results in an equal force in an oppssite directionRate this question:
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- 41.
What are the three forces action upon a rocket during the course of its flight?
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Thrust, Rocket Diameter and finish
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Nose cone shape, thrust and drag
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Gravity, thrust and aerodynamic drag
Correct Answer
A. Gravity, thrust and aerodynamic dragExplanation
Gravity, thrust and drag are the forces acting on a rocketRate this question:
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- 42.
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?
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The CG must be behind the CP relative to the desired direction of flight
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The CG must be forward of the CP relative to the desired direction of flight
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The CG must move forward (in the desired direction of flight) during the motor burn
Correct Answer
A. The CG must be forward of the CP relative to the desired direction of flightExplanation
The center of pressure (CP) is where the aerodynamic lift, due to the rocket being at a non-zero angle of attack, is centered. For an aerodynamically stable rocket with the CP behind the center of gravity (CG), the lift which is centered aft of the CG will create a corrective moment to return the rocket to zero degrees angle of attack. Conversely, if the CP is ahead of the CG the lift will attempt to turn the rocket around so that the CP will again be ahead of the CG. This resultant "tumbling" is characteristic of an unstable rocket.Rate this question:
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- 43.
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?
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No, the CG should be at least two body diameters behind the CP
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No, the CP must be behind the CG for the rocket to be stable
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Yes, the CP is one body diameter in front of the CG
Correct Answer
A. No, the CP must be behind the CG for the rocket to be stableExplanation
The rocket is not stable because if the rocket rotated around its center of gravity (CG), the greater aerodynamic force forward of the cg would cause the rocket to rotate even farther, resulting in an unstable flightRate this question:
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- 44.
What is the “rule-of-thumb” for a stable rocket?
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That the center of gravity should be at least one body diameter in front of the center of pressure
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That the center of gravity should be very nearly at the same point as the center of pressure
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The rocket should balance near or at the center of gravity
Correct Answer
A. That the center of gravity should be at least one body diameter in front of the center of pressureExplanation
Keeping the center of gravity (CG) one body diameter in front of the center of pressure (CP) typically allows an adaquate margin for rocket stability.Rate this question:
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- 45.
What effect does a boat tail have on a subsonic rocket’s coefficient of drag (Cd)?
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No effect, a boat tail is only a cosmetic design feature
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It incrases the Cd by changing the airflow over the fins
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It decreases the Cd by reducing the base drag
Correct Answer
A. It decreases the Cd by reducing the base dragExplanation
A boat tail on a subsonic rocket reduces the base drag, which in turn decreases the coefficient of drag (Cd). Base drag is caused by the pressure difference between the front and rear ends of the rocket, and the boat tail helps to smooth out the airflow and minimize this pressure difference. As a result, the Cd is decreased, improving the rocket's aerodynamic performance.Rate this question:
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- 46.
A bates grain has an essentially neutral thrust curve because:
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Core burning motors always have a neutral
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The area of burning propellant remains relatively constant
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The core is centered in the propellant grain
Correct Answer
A. The area of burning propellant remains relatively constantExplanation
The correct answer is that the area of burning propellant remains relatively constant. This means that as the propellant burns, the surface area of the burning propellant does not change significantly. This results in a thrust curve that is essentially neutral, meaning that the thrust produced remains relatively constant throughout the burn time. This is in contrast to other types of thrust curves, such as increasing or decreasing thrust curves, where the thrust produced changes significantly over time.Rate this question:
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- 47.
What is the most common oxidizer in commercially available high power composite solid rocket motors?
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Ammonium Perchlorate
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Ammonium Nitrate
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Ammonium Chlorate
Correct Answer
A. Ammonium PerchlorateExplanation
Ammonium perchlorate is the most common oxidizer in commercially available high power composite solid rocket motors. It is widely used due to its high oxygen content and stability. Ammonium perchlorate provides the necessary oxygen for the combustion process, allowing the rocket motor to generate thrust. It is a highly effective oxidizer and has been extensively tested and proven to be reliable and safe for use in solid rocket motors.Rate this question:
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- 48.
What typically happens to a marginally stable rocket with a hybrid motor during the thrusting phase?
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Nothing
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The rocket may become more stable
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The rocket may become less stable
Correct Answer
A. The rocket may become less stableExplanation
During the thrusting phase, a marginally stable rocket with a hybrid motor may become less stable. This is because the thrust generated by the motor can cause changes in the rocket's center of gravity and center of pressure. If the center of gravity shifts too far forward or if the center of pressure moves rearward, the rocket's stability can be compromised. This can result in increased wobbling or even loss of control during flight.Rate this question:
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- 49.
In general terms, the total impulse of a rocket motor can be described as:
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The product of the average motor thrust and burn time
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The product of the propellant weight and burn time
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The product of the propellant weight and the motor thrust
Correct Answer
A. The product of the average motor thrust and burn timeExplanation
The correct answer is the product of the average motor thrust and burn time. This is because the total impulse of a rocket motor is determined by how much force the motor produces (thrust) and how long it produces that force (burn time). By multiplying these two values together, we can calculate the total impulse generated by the motor.Rate this question:
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Mar 21, 2023Quiz Edited by
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Mar 24, 2015Quiz Created by
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