PatR
Premium Pilot
The Air National Guard has been operating large, fixed wing drones around several east coast urban areas. Just for an altitude reference, Predator/Reaper cruises at 25,000’ and above, Global Hawk at 35,000’-40,000’+. Some of the smaller drones like Aerosonde, Scan Eagle, Shadow, and RQ-21 can easily exceed 18,000’.
As for climb rate for multirotors, some of the FC systems provide for user adjustable climb and descent rates. APM, Pixhawk, PX4 are some that quickly come to mind. Some people have been “hacking” DJI code and altering previously limited performance parameters. If you have the thrust and battery capacity you can achieve 10,000’+ and get back.
In early days I used to set the climb rate on APM systems with a max climb rate of 10m/s to 15m/s. Whether or not they actually achieved that that rate in practice is open to question but they ascended very quickly. Descents were a lot slower as I learned setting a high descent rate could force the FC to stop the motors to achieve it. When that happened it wasn’t “descending”, it was falling out of control. Unless you had considerable altitude when you re-applied power to stop the tumble and right the aircraft the “arrival” was quite destructive. It required several hundred feet to stabilize. Lessons learned the hard way...
So it’s possible for a multirotor to be seen at 8,000’, but not probable unless the operator launched from the top of a high terrain feature.
As for climb rate for multirotors, some of the FC systems provide for user adjustable climb and descent rates. APM, Pixhawk, PX4 are some that quickly come to mind. Some people have been “hacking” DJI code and altering previously limited performance parameters. If you have the thrust and battery capacity you can achieve 10,000’+ and get back.
In early days I used to set the climb rate on APM systems with a max climb rate of 10m/s to 15m/s. Whether or not they actually achieved that that rate in practice is open to question but they ascended very quickly. Descents were a lot slower as I learned setting a high descent rate could force the FC to stop the motors to achieve it. When that happened it wasn’t “descending”, it was falling out of control. Unless you had considerable altitude when you re-applied power to stop the tumble and right the aircraft the “arrival” was quite destructive. It required several hundred feet to stabilize. Lessons learned the hard way...
So it’s possible for a multirotor to be seen at 8,000’, but not probable unless the operator launched from the top of a high terrain feature.