system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a limit to how big a plane can get and still be able to fly?
gpt
There is a limit, but it is a larger limit than is likely to ever be attempted. Assuming we are able to increase the thrust in the needed proportions, the problems become primarily weight, integrity, lift and form.

Weight becomes an issue because one must have sufficient fuel to power sufficient engines to move the plane at sufficient speed to remain airborne. As you add more to the plane, the weight increases, the thrust needed increases, the number of engines increases, and the amount of fuel needed increases, which then increases all of those again.

Tied in with that, the materials must be strong enough to not bend with all of the weight well as resilient enough to not significantly warp out of position due to that weight, as well as the drag generated by the air and the thrust generated by the engines. But it also must be as light as possible while doing so.

Assuming you are somehow able to discover ways to compensate for all of this, the answer would be defined by what criteria the design needs to fit. If it doesn't need to be manned, no space for humans needs to be allocated. If it needs to be able to land, it must be able to fit an appropriate runway.

Theoretically, if you had perfect materials and were able to compensate for the weight and thrust requirements, you could design a plane large enough to require a downward sweeping design to fit the curvature of the earth.

But for the moment, the planes we have already are about as big as they can be while still making sense and being financially viable.