I purchased my first drone with the hopes of being able to fly reliable, repeatable, long distance missions for survey applications.
After wasting 6 months and $25,000 on a top of the line S1000+/Zenmuse/Dual Futaba system, I purchased a Phantom Pro 3 and very quickly saw how wrong I had been.
After experimenting with various ways of getting up and down safely with images that will stitch into Agisoft Photoscan, I settled on Ultimate Flight because the developer was so responsive to my questions and suggestions while I was learning.
Ultimate Flight allows you to define a complex missions using a PC/Mac based upon Google Earth KML polygons, then load and fly them from auto-takeoff to auto landing, including all the required camera controls such that a relatively untrained operator, like a farmer, can fly missions and end up with the same number of drones he started with.
With my S1000+ system the largest polygon I have ever been able to image in a single flight from a legal altitude was 50 acres, and the poor thing was exhausted on landing.
With a P3P I have been able to routinely image areas up to 180 acres from 100M, and 250 acres from 150M.
Both of those missions are around 7500 meters total length. A 7500 meter mission will land with about 30% battery left, but I don't recommend missions longer than that because wind can cause an extra drain on the battery. The folks I work with are interested in images, not excitement.
With a single P3P during a 4 hour period, using 5 batteries and a 12v inverter for the battery charger, I can expect to cover 1000 acres with little or no drama
I cannot imagine flying a mission of any length with Ultimate Flight because once you define a waypoint grid you get a very good idea of how long it will take to fly it. If the mission exceeds what a single battery will safely bear you can either increase the flight speed or raise the altitude. Speed and Altitude both affect Photoscan though, so there is a point where you have to decide to break the mission into 2 battery flights.
When you do fly a predefined mission in Ultimate Flight, the screen shows a bright red circle that represents the farthest distance you can fly and still hope to have enough juice to come home. On longer missions I watch that circle slowly close in towards the end of the flight, but I've never yet had a mission not bring the platform home safely.
For most survey missions we create, the maximum distance to the platform usually doesn't exceed 1500 meters, but with an autonomous flight it doesn't matter if you lose the R/C signal because the platform will continue to fly the mission regardless of its ground connection.
Ultimate flight has other features I have used from time to time for shorter missions to do survey volume calculations like the ability to define circles with the gimbal pointing at a certain spot on the ground or in the air and the ability to define missions where the platform flies sideways to get oblique images of something like a containment berm.
Another feature I have used several times is the ability to fly a mapping mission, create an orthophoto from that mission, then load that geo-referenced image into Ultimate Flight to give an up to date background for future flights. Since some Google Earth areas can be many years old, this has been very useful for construction and volume storage calculations like piles of asphalt and gravel.
To be honest, Ultimate Flight has a bunch of features I have never used and don't understand like a virtual wall to prevent you from hand flying outside a defined area, fancy camera settings, the ability to adjust waypoint heights based upon Google Earth elevations, and both inward and outward panorama missions.
For me though, the ability to define a mission at home, understand and control the risks, then fly with confidence is the only way to go.
Hank
Texas