Just read a good funny French article about Batman ... It says; in real life the caper would have died with multiple injuries if he stays close to his current styled outfit. For that Batman can fly he would need either a larger, wider cape or using some sort of jet propulsion.
One of the studies pointed out that jumping from a 150m building, Batman can glide for about 350m with a 4.7m cape span ... but would be fatally hurt hitting the ground at 80hm/hvia
They recommend that our hero goes on a shopping spree for other outfits before attempting jumping real Gotham City buildings