I only thought of planting french beans when the corns were almost time for harvest- because i was lack of stakes to make a trellis for the beans. French beans wound themselves very quickly around and used the cornstalks (i.e. the natural trellis) as support.
Later when the cornstalks bent under weight of the beans and became crisp, i added in some stakes and a 4-ring support to hold the weight of the beans. This is how the whole thing looks like now.
I read that the combination of corns and beans work well as the beans pull nitrogen into the soil while the corns use the nitrogen. I'm doing this combination again in another raised bed but this time i added pumpkins in to make a Three Sisters planting. This not only can have a real impact on the health and yield of the plants (as per the articles), but will also save me so much space!