HELP! Unknown reason for plane crash during Manual

Hi! Can anyone help us understand the cause of our plane crash last Jan 31, 2019? We were about to tune our newly built Skywalker but unfortunately, it crashed during Manual mode. In the dataflash log, the flight duration is only until 50 seconds and the remaining time was the actual crash and recovery.

We would like to know what can possibly cause this. Attached are the log files. Thank you.

First, I notice that your ailerons and elevators are set to reverse (both in the log and in the extracted param files). I assume that is deliberate, and you have checked the control surface deflections to be correct before flight?

Next,while your aircraft was climbing, the airspeed (15m/s) looked rather low:

From the graph, it seems that the aircraft was climbing but entered a stall due to the insufficient throttle input and resulting low airspeed. This caused the dive as seen at the right of the graph.

You need to input more throttle than usual during the climb phase as you are fighting against gravity while climbing. 60% throttle (which is usually the norm for cruising) might not be enough.

That is all that I can tell from the brief look at the logs; feel free to correct anything wrong with my reasoning or point out something that might have been missed out (:slight_smile: