Hello everybody i was wondering if i can build high speed "up to 200mph" plane that can be controlled autonomously by an IMU such as APM..the plane is jet powered & the engine provides thrust up to 27 newton, the whole objective for the plane is to travel up to 5 kilometers at low altitudes "10-15 meters" and circle around and come back, is this doable because i heard that GPS's is tuned down to have slow transfer rate and wont be efficient at such high speeds.
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Jack,
To explore the technical issues, just buy the APM kit and X-Plane, and run it in HiL (Hardware-in-the-Loop simulation.) I've flown several planes at speeds significantly faster than 200 mph successfully. Of course, X-plane is feeding the GPS values at 50Hz, but the ArduPlane is still only handling them at in the 10Hz loop, it uses the same code, it just hooks the sensors and output, so it should work fine. There is also a slower GPS unit, 4Hz, but if you really want to see that, you might create a timing filter in your experiment, and drop out a little more than 1/2 of the GPS update cycles. I still do not expect you to have any real problems, but you might want to ensure that important waypoint turns have a radius of at least 35-40m, or make a series of waypoints with a wide radius and a more gradual turn angle. At speed, you might need turn radius of less than 10 degrees, but please do your own math here, I'm just picking a quick number.
Now, as far as actually operating a UAV like this in US national airspace, I suspect that would not be consistent with FAA regulations. Noting in the speed itself is a issue, I think, but please look into the requirements for UAV flight in your area.
The distances away from the operator and the (un)likelihood of finding safe flying areas that are 5 kilometer long at 10-15 meters high, without people. These might make it very difficult to operate your UAV within the FAA guidelines, maintaining line of sight and obstacle sense and avoid, and ensuring it is maintaining a safe distance from the public and buildings. Maybe someplace in the Nevada desert? It's still hard to see the plane for 5 kilometers, but maybe you could have spotters with radios and a FPV system for the pilot?
Legal issues aside, and GPS data speeds aside, I think your real problem is going to be tuning your PIDs with an aircraft this fast. At these speeds, you might go through a lot of aircrafts and APMs before you get stabilize tuned in well. I don't see much hope of recovering any useful parts from a collision at 200mph crash. And then you might lose just as many finding the right navigation pids so that your waypoint turns do not become a flat spin or corkscrew into the ground. This is especially true since you're talking about 4.5g in a 23 degree turn at 200mph, more or less. So you're very likely to easily or accidentally create a mission script that, if followed by the APM, would tear the plane apart, put it into a flat spin, or other ugly things. Which goes back to the first paragraph... you will likely need to plan any turns correctly, and make sure you are neither asking the APM to exceed physics or the capabilities of the aircraft. This sort of takes care of itself, mostly, since you are going to need to build it as an RC plane first, and fly and tune the platform for manual flight first.
But get an APM kit, assemble it, and get X-Plane, and see for yourself.