If you are designing a new car engine there isn't always of the shelf software already designed and tested. There are instances like the Ariane 5 maiden flight[

If you are designing a new car engine there isn't always of the shelf software already designed and tested. There are instances like the Ariane 5 maiden flight[1] where Ariane 4 software was reused. [1] http://www.di.unito.it/~damiani/ariane5rep.html http://www.di.unito.it/~damiani/ariane5rep.html