I am planning on building a quadcopter that uses a Raspberry Pi as a flight controller. I am busy playing around with designs and the best one I have created so far has an estimated hover time of 10 minutes. I would like to increase this hover time to be around 20 minutes. Before listing the drone parts, I would like to add that this drone will have a ~550g camera setup (including gimbal) and the frame will be built from aluminum (which I am estimating will be 600g). I have estimated the entire weight to be around 2500g which may well be way off.
Here are the parts:
The build might be a bit overkill since it has a ~2.9 thrust-weight ratio (I would like this to be above 3 in case my weight estimate is far off). This kit is already very expensive (I am trying to stick as close to $400 as possible) so increasing battery size isn't the best idea as it will dramatically increase the price. I have only recently started looking at drones so I don't have many ideas to optimize for flight time and cost (I played around with a octocopter design but it was more expensive due to the ESCs and had similar optimization problems). Any recommendations would be really helpful :)