B. Engineering Rules

V0.1 - 22-06-2020

EDL subsystem engineering rules

The following rules should be followed during the design and development of an EDL system.

On the vehicle and system design:

  1. Keep it simple, it is already hard enough
  2. First make it fly, then make it better
  3. [alternative] If a system does not work, you cannot make it better
  4. An overly complex system is only good as a museum piece
  5. Keep track of requirements, even if only used to establish a clear line of blame
  6. Do not change the requirements without consulting the entire team. Or just do not change the requirements
  7. Assume everything goes wrong
  8. [alternative] Plan for the worst, prepare for the worst, assume the worst
  9. When implemented wrongly, redundancy reduces the probability of mission success
  10. When designing a system keep producibility and testability in mind


On systems engineering:

  1. Every system you include requires introduces additional V and V
  2. Every system you include introduces interfaces, which require additional V and V
  3. [alternative] If you do not need a subsystem, do not include it
  4. Just because you can, does not mean you should
  5. Find a solution that works, even if it is not the best
  6. The optimal solution is always in the middle and never at an extreme
  7. Mechanical and electrical engineers do not speak the same language. Find a systems engineer to translate
  8. The most important person in your team is the person responsible for Assembly Integration and Testing (AIT)
  9. If you do not have an AIT person, good luck
  10. Test as you fly and fly as you test
  11. Test test and test again
  12. [alternative] If you think you have tested enough, test again
  13. Keep the number of interfaces to a minimum
  14. Interfaces with external parties count as ten interfaces

On (EDL) simulations:

  1. Every model is wrong, it is up to the engineer to accept how wrong a model can be
  2. Monte Carlo is a simulation engineer’s best friend


On atmospheric entry:

  1. If your vehicle gets too hot, play with the ballistic coefficient
  2. The ballistic coefficient is an entry engineer’s best friend


On parachute systems:

  1. If somebody claims to be a parachute expert, he is not
  2. The smaller the parachute, the larger the accuracy needed to keep it stable
  3. Stable cross parachutes do not exist
    1. [After seeing a stable cross in the wind tunnel] Even cross parachutes can be tamed
  4. If an unstable parachute is stable in flight, it is not stable it just glides
  5. Avoid supersonic inflation
  6. If supersonic parachute inflation cannot be avoided, avoid transonic parachute inflation
  7. If transonic parachute inflations are unavoidable, change your ballistic coefficient. And see the above two rules


On landing systems:

  1. Do not forget the landing system

V0.1 - 22-06-2020