In a far23 certified aeroplane, you donīt use V1 Vr. According to certifications requirement the far23 plane doesn't have to be able to climb with a engine out. Most far23 manuals advise that IF landing straight ahead is possible, do so. And if not... well to bad. As my old instructor said: "why does an aeroplane have two engines...? Because it wont fly on one!!" Some truth in that.