how heavy drone
Legally, in the US, civilian drones are limited to a maximum takeoff weight of 55 pounds. Conceivably, if you build a drone that is 20 pounds including batteries, and if it has enough power you could lift about 35 pounds. Most of the commercial heavy lift drones today max out in the 20 pound range. If you're looking at higher end consumer drones, (3dr, yuneec, DJI) most top out with a payload of only a couple pounds. I should point out that there is quite a difference between the absolute maximum payload, and the maximum rated payload.