Tra - Level 2 CERT - Tech And Safety
Working on my Level 2 cert for TRA
- 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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