Ok, let me clarify. If you put that ship, as-is, into an atmosphere and kicked in the engines, you'd have an unbelievable amount of drag coming from the leading edges of the wings. And the airflow off the back would be so turbulant that you'd probably completely lose control of the ship. "Atmospheric" fighters should look like planes, no hard edges facing directly into the direction of flight.
And if you aren't going to beef up the ship under the premise that it has to look "sleek", you're really going to want to bring those hard edges under control. Right now it's got the biggest radar cross-section possible for a craft of that size.
I actually think the design has a lot of promise, it's just way too square.
