Sponge cake: excessive cooking time
A couple things:


Unless the recipe (or experience) says otherwise, place items in the middle. Putting something higher in a conventional (non-convection) oven should make the top cook quicker than the bottom. This may account for the top drying out when the rest isn't done yet.
As @ElendilTheTall says, check your oven temperature. Your oven is probably running much lower than it should be. On most ovens, you can adjust the dial so its right.
Make sure you're using the same size (and material) pan as the recipe. Thicker cakes take longer to cook, and some pan materials are slower than others.


I looked up several recipes, and all gave times under 30 minutes.