Hey there all.
Before I go away and madly assemble my Mega, I was wondering if anyone has had experience with running one in;
A: A very large airframe.
B: Hi vibration environments.
My airframe has a wingspan of 11 feet and runs a 111cc Horizontally opposed 2 cylinder which is supposed to be low vibration...
Now, i'm sure it is low (when compared to a jackhammer) but when compared to a electric motor it's definately not.
I have taken some design cues from various other UAVs and will be doing my best to isolate engine vibration from the airframe but was wondering if anyone has any clues as to what i'm likely to expect from using the Mega in this type of installation.
I'm also interested in whether different mounting positions within the airfram could have benefits.
Could the APM be mounted in the rear of the aircraft (inside the aft fuselage structure) or does it have to be centered near the aproximate pitch/roll/yaw axis "intersect point" within the airframe to be most effective?
Many thanks!
JC
Replies
John,
The size of the airframe will only cause you issues if you do not pay attention to power distribution. EG if you have a bunch of big high current servos you may need to handle power distribution to them in some other manner than through the APM servo bus.
Vibration is a much more difficult matter. We have seen problems even on electric airframes due to poorly balanced propellers. The APM code includes a metric called IMU health. If you cannot keep the IMU health value from falling to zero due to vibration then you cannot expect reasonable performance. I don't have any suggestions for figuring out if APM will work for your airframe other than trying it (either an extended high throttle run-up on the ground, or a flight in manual mode) while logging some data and seeing how the IMU health metric behaves.