Another loss of altitude (in AltHold) post!

I was testing my f330 build today (actually went out to run autotune) with 3.3.2rc2 running on an AUAV-X2. In AltHold I am getting considerable altitude loss in forward motion, even walking pace motion (more than 6 metres drop), then on slowing the craft to a stop, it ascends back to the original altitude. I have the AUAV-X2 fitted inside a 3d printed (by Trincle in Germany) case for which the design was provided by the board developer Nick Arsov. The case has foam fitted over the baro (the case actually has a recess built in for this specifically).

3691257854?profile=original

The copter is a 330mm (DJI F330 clone) which is quite over-powered - I have THR-MID set to 300 for a guide on how over-powered this is. its running SunnySky v2814-870kv motors on 4s 65c 2600mah LiPo with 8045 carbon-plastic Gemfan props.

3691257592?profile=originalI captured a log during the auto-tune flight (I will attach this in a minute as my macbook card reader is playing up!). If anyone is able to comment as to the altitude behaviour and how I could look at reducing this phenomenon, that would be awesome, and most gratefully received. Best Regards, Paul 

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  • zipped log file attached.

    Think I might have an idea but comments are appreciated. In the log I found this:

    3702130427?profile=original

    it shows the baro-alt against the GPS-Alt and also the GPS speed. It suggests that as I speeded up the baro saw a higher pressure and therefore the craft thought it was ascending, so started to drop the throttle, and hence the descent to almost the ground. In fact though, the GPS-Alt shows the true story. So I am thinking that maybe I need to put better foam over the baro. What do you guys think?

    4.BIN.zip

    https://storage.ning.com/topology/rest/1.0/file/get/3702130444?profile=original
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