An evil empire is besieging a floating city. While not particularly high off the ground, none of the siege weapons can reach it effectively. They also need a way to get troops into the city.
An imperial engineer comes up with a design:
A large ballista fires a glider as far as it can into the air. The glider is essentially a smaller, winged ballista that fires once it reaches its peak height. The idea is to have the second projectile tied to a rope, allowing soldiers to climb up to the city.
Some background info:
- The world is low magic fantasy. The city floats by unknown powers, and there are no magical flying machines.
- The city is situated on a plain, so the ground around it is relatively flat in every direction.
- The tech level is between medieval and industrial revolution, however gunpowder and airships do not exist yet.
- The height at which the city floats at is not set in stone. This can be adjusted.
- The city is stationary.
- Each nation is a single city state, barring the Empire, which is consuming nations one by one.
- The nation being besieged is a nation of scholars, scientists and strategists - some of the greatest minds in the world.
- In order to minimize reliance on the ground, the city has a self contained water system.
The inhabitants have a large view radius, and thus have fair warning of the approaching army. All non military personnel are evacuated and take refuge in friendly neighboring states, leaving only the small but efficient army to man the battlements. The king and his son remain to command the troops. With only a few hundred men, the preserved food stores would allow the defenders to hold out long enough to make a prolonged siege very costly.
At the end of the day the city must fall for the story to progress, but I can't think of a way without airships/magic to do this. I could allow gunpowder and have them blast it out of the air, but I need enemy soldiers to infiltrate the city for plot reasons.
Is this two-stage ballista solution plausible, and if not, what alternatives/alterations should be looked at?
EDIT: I'm strictly looking for mechanical solutions. Assume that the defenders are extremely loyal and have the greatest disdain for the enemy
Notice: Apologies for not replying to comments etc. I kinda have a medical emergency, but will go through everything once it's passed. Thanks for all the answers!