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Chapter 8
8.1 What is a PRA?
8.2 In your own words give a definition for the RBD.
8.3 What is the difference between series and parallel components when it comes to
calculating reliability?
8.4 What does QC stand for?
8.5 If a rocket system is determined to be extremely low reliability because of
complexity in design, how can the reliability risk be reduced?
8.6 The Russian Proton rocket has 6 engines on the first stage, three on the second, and
1 on the third. Assuming no other risky components exist on the rocket (engine
based assessment only) determine how reliable each engine must be to make the
Proton 90% reliable.
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8.7 Explain how Rocket Design Rule #2 is important when it comes to improving a
rocket’s reliability.
8.8 Calculate the probability of success (reliability) of the complex system shown in
Figure 8.8. For the system use the following values: R1=R3=RN=0.91, R2=0.8,
M=8, and N=9.
8.9 If a rocket system has been tested less than 150 times, its probability and reliability
assessment (PRA) should be reliable, unreliable, or unknown?
8.10 For the hobby rocket you designed in OpenRocket for Exercise 7.7 draw and RBD
to the maximum level of detail available.
8.11 For the RBD developed in Exercise 8.10 calculate the PRA. Make reliability
assumptions as best you can based on test data, personal experience, and literature
available on the Internet and within OpenRocket.