Q:

Heavier Rockets Launched By Planes

Would it be physically possible to use a plane to assist heavier rockets with their launches (I know orbital ATK launches their pegasus rockets from planes but would it be possible to launch something closer to the Falcon or Atlas class) 

A:

The largest payload ever lifted by an aircraft is around 250 tons for the Antonov An-225. The Arianespace Vega can orbit about 2.5 tons from a starting weight of 130 tons, so the An-225 could be used as a starting point for a launcher with a 5-ton capacity to LEO. 
A Falcon 9 weighs 550 tons. 

