Well it's a sad weekend. On Friday my Skwalker had a second catastrophic nose dive and I lost it somewhere over a marsh. Scanning the area with a FPV had no success.
I've made peace with the loss, I'm just trying to understand what caused the nose dive. It just would not pull out of it, and it's the second flight with the second indecent (the first crash I could recover).
It started since I moved the heavy 6000mAh battery right to the front, before you point to the seeming obvious, the CG was still too far back and tail heavy, despite this, as those who have the skywalker know.
What platform should I buy next? I'm worried about buying a Skywalker again, because of this.
Thanks Darren, no I had the laptop turned off, I was just flying to see if it handles better after the fix. I have telemetry of the previous crash, though.
Sorry to hear that. How many flights had it done? Any number of reasons could cause an unrecoverable dive, starting with a failing servo, or servo linkage, or the control surface itself. It seems it's best to plan on losing a drone some day rather than just hoping for the best, even when one does not plan on doing anything complicated.
Only four flights! The first one was fine, with a lighter front load and the CG further back. Third and fourth I had the heavy battery in front.. Where should the CG be on a Skywalker?
I have read that it is good at between 60mm - 70mm from leading edge of the wing, but I do not know from experience.
Sorry for your loss. Sorry you did not have telemetry also, as that may have been interesting, and also helped to find the plane.
I have heard good things about skywalker. I have three Bixlers waiting for their first flight on my bench.
How heavy is the 6000mAh battery? How heavy AUW?
The battery is (was) 481g, what is AUW?
Sorry, All Up Weight - http://en.wikipedia.org/wiki/Aircraft_gross_weight
Oh right - sorry not sure. The SW itself is apparently 2.5kg, add the battery and the motor etc, maybe 3.1kb.
@Hein, I think you exceeded the Vne of the aircraft or stalled the aircraft. I run a Spektrum telemetry setup on my Skywalker with an airspeed indicator. I noticed that when I got over 100 km/hr indicated airspeed the SW handled like crap, on a couple of occasions I was full throttle and the plane was going down, and elevator wasn't helping, once I backed off the power I got my elevator back again. Many people on RCGroup have crashed their SW with snapped wings and many have said they were in a dive.
The other thing that might have happened (which happened to me) is that the control throws were too high. A couple of occasions I entered a turn, and either went into a spin or the aircraft just stalled and I couldn't maintain altitude. The recommended control throw for the SW is 15 degrees with a CoG just forward of the servo lines. Mine was setup originally with 30 degrees :-) and the CoG nose heavy about 10mm forward of the servo lines, it flew fine.
If your CoG moves back (like it did when I removed the FPV pod and went to a smaller battery), the aircraft becomes less stable and responds more quickly to control surfaces, this amplifies the control surface throws, so whilst 30 degrees was OK nose heavy, it wasn't ok when the CoG was moved 20mm aft of the servo lines. The aircraft would bank and want to keep going if there was an wind.
I've reduced my throws to about 10 degrees and my CoG is 15mm aft of the servo lines, and I don't have those issues anymore.
The weight of your SW doesn't sound right at 3.1kg.
My SW with 4S 5000Mah and FPV gear weighs in at 2.0kg. I recall that the battery is about 600g and the 4S 6000Mah which I also have flow with is 100g heavier.
The BEW of the SW is more like 1.3kg with a TOW of about 2.0kg depending on the battery and any extra gear. If your SW is 3.1kg I definitely think your SW stalled and crashed.