placement of long/longue

In lesson 6.8 -

Example 1: C’est la plus longue partie du livre. 

Example 2: Ce vol est le plus long.

For example 2, why not:  C'est le plus long vol.

Is long/longue an adjective that comes before or after the noun?

Merci

I suppose “long/longue” is part of the BAGS (beauty, age, goodnes, SIZE) adjectives, that go in front of the noun. Not 100% sure though

That's what I was thinking until I ran across example 2 where the adjective was after noun.

Michael, FYI, you're comparing apples and oranges. In your second example the adjective is not after the noun. It's after the verb.    Noun + is + adjective.    Not likely that you're ever going to see this sentence structure in reverse.