This short tutorial will show you how to effectively create a flying machine that will also have bombs. With this method you can create any flying machine and add different parts to it.
Note for the bomb attaching - you need to use a block/holder to attach the bomb and then replace it with a grabber. It's a bug in the game that still hasn't been fixed(or its just how the game works)

The machine used was created by Dhakir and submitted to http://petardia.com/besiege
If there is enough interest, I can make a step by step written tutorial as well so make sure to let me know do you want to see something like that.