RE: Survival Bow
I am an engineer and I seriously doubt you will be able to carve a strong enough riser and attach it firmly enough to the limbs to be able to get an arrow fast enough to either kill something big or hit something small.
If you're looking for something to defend yourself from an animal, bear mace, aspear, ora machete will do better than a homemade bow.
If you're looking for something to help you survive on small game, how about a slingshot, takedown bow,pistol crossbow, or blow gun.
Mike