NAR HPR Level 2 Certification Practice Exam: Section D - Rocket Stability

There will be (3) questions on the actual exam from Section D's (8) question pool. For each question below, click on the circle next to the correct answer. When you have finished the test, Click the 'Score My Exam' button at the bottom of the page. Good luck!

 

Question D1
For a rocket to be stable which of the following statements is true?

A. The center of pressure (CP) must be behind the center of gravity (CG)
B. The center of pressure (CP) must be in front of the center of gravity (CG)
C. The rocket must have fins
D. The length of the body tube must be at least 5 times the model diameter

 

Question D2
An unstable rocket can be made stable by:

A. Adding sufficient weight to the nosecone
B. Removing sufficient weight from the nosecone
C. Moving the fins sufficiently forward towards the nosecone
D. Making the rocket sufficiently shorter

 

Question D3
Rocket stability can be estimated by:

A. Center of pressure “Barrowman“ equations
B. “Cardboard cutout“ method
C. Determining the relative positions of the center of pressure and center of gravity
D. Stability cannot be estimated before a test flight

 

Question D4
A rocket’s center of pressure can be estimated by:

A. The “Barrowman“ method
B. Finding the point where the model balances
C. “Cardboard cutout“ method
D. Both “A“ and “C“ above

 

Question D5
An unstable rocket can usually be made more stable by:

A. Using a shorter nosecone
B. Increasing the size of the aft fins
C. Using a larger, heavier rocket motor
D. Increasing the rocket diameter

 

Question D6
During boost a rocket powered by a solid rocket motor tends to become:

A. Less stable in flight
B. More stable in flight
C. No change in stability
D. Unstable

 

Question D7
Which of the following can cause unstable flight?

A. Weak tubes or couplers that permit airframe bending
B. Misaligned motor mount tube or motor nozzle
C. Inadequate airspeed leaving the launch tower on a breezy day
D. All of the above

 

Question D8
As a rule of thumb, how far should the center of pressure be from the center of gravity?

A. The center of pressure should be at the same location as the center of gravity
B. The center of pressure should be at least 1.0 body tube diameters behind the center of gravity
C. The center of pressure should be at least 1.0 body tube diameters ahead of the center of gravity
D. The center of pressure should be 1.0 body tube diameters ahead of the fin leading edge; the center of gravity does not matter

 


Move to:

Section A

Section B

Section C

Section E