Alright... once in a while a maiden flight doesn't go so well, this is one of those times...
Obviously the CG was a little far back and the throws/size on the control surfaces were WAAYYY to big. I'm telling you, it was almost un-flyable.
Luckily, a quick repair job and some adjustments and we'll be back in the air.
We just got an APM2 in the mail, so when the Shrike is doing the right things we can finally get into some drone action!
Until Saturday,
-Trent and Nick
Comments
"Don't let the autopilot sort out a badly trimmed airframe, you will need to hand fly it on occasion and you don't want the thing all out of shape when you take over."
When I flew my Zephyr II for the first time it was a fight for survival. The CG was correct, but the trim was too far down (no "up-kick") and the throws were 3+ times of what the airframe needed. I managed to land, but flying constantly with that much back pressure is difficult (trim range was not enough and hard to trim while fighting the plane). Flying the same configuration with APM in FBW mode flies great. I can take it high up, switch it to manual and work on the trim and determine the throws needed.
Also the APM can help getting such a badly trimmed airframe off the ground instead of crashing hard on take-off. But maybe one could argue it's better if did not get airborne ;)
Yes the final goal is to have a plane that is flyable in manual mode. But the APM can help you to get there. Of course APM cannot compensate for major CG problems.
These days I only take-off in FBW mode when launching my Zephyr II. The APM will keep those wings level, no matter how slow or crocked the throw was.
Monte Carlo methods always involve iterative processes...
Wings always seem to need more on the nose than you think. Start with the CG forward with a wing and move it back.
Don't let the autopilot sort out a badly trimmed airframe, you will need to hand fly it on occasion and you don't want the thing all out of shape when you take over.
Big mistake letting the autopilot sort out heavily laden badly rigged airframes. Many of the "mystery" crashes here are due to that I am sure.
If you get the airframe flying right it will give you better performance and longer flight times.
That was not a pilot error problem at all. Unless the pilot was the design engineer. In this case it would be a design problem and the pilot is not at fault.
I know you can fly, but that craft was uncontrollable. Why? Yes there was too much control angle, but it also seemed to be tail heavy, and thus very unstable. With a flying wing, CG is even more critical. Was the CG ok before launch. OK. Was the CG the same after launch. In other words did your battery shift back when it was thrown? Of course you don't know, but that's what is most likely. I assume the plane form and CG is the same as the first wing.
I built an unflyable plane when I was about your age. It was a canard and only flew twice. Crashed both times.
That was ~ 30 years ago. Man, am I gettin old.
Setup your APM2 in FBW mode and you will be able to fly any plane, even completely wrong trimmed and throws that are way too big ;)