losing altitute with big x8

[twistedshifter]

Hmmm. Not sure that's going to help.
Here's an in depth discussion of the problem :
http://diydrones.com/profiles/blog/show?id=705844:BlogPost:1802585&page=1#comments

3DR tried to mitigate the problem by adding open cell foam inside the Pixhawk Flight Control case over the Baro sensor.
All agree that it's best to mount the FC inside and out of prop wash.

Some people tape shut every unused opening in the FC to lessen the pressure shift inside.
Others have encapsulated the Baro sensor and run a tube out to either the front of the UAV (trying to get ahead of the pressure bubble of an oncoming UAV) or up the GPS mast in order to take Baro readings in air less disturbed by prop-wash.

This is the discussion I have been long waiting for. I have a custom built 550mm F450 Naza V2 400KV 13" props 6S 8000MAH and it flies awesome.....holds altitude flawless in FF. I have the exact same spec Disco Pro....same motors, props, Naza V2 and battery and it drops like a rock in forward flight. I enquired several times with Trappy on why the Disco Pro will not hold altitude in forward flight and he said it is normal. This cannot be normal if I have another machine with same spec/weight that holds attitude in FF perfectly. The only thing I could see effecting the flight was the arm geometry being different on the Disco Pro. I have double checked my COG and it is spot on with the Disco Pro. Now I am thinking it could perhaps be the IMU location sensing the pressure differences. Anyone else with Disco Pro had this problem with FF? I have learned to deal with it and just add throttle, but I am baffled how my other machine I don't need to do this. Thoughts?
Thanks guys.

 

[Carapau]

Well, I added some open cell foam baffles to my IMU and tested it today. It did sweet stuff all but that is kind of what I anticipated. The air is still moving over the foam causing a pressure drop around the foam and you cant hid that from the sensors. So I suspect that it is something baked in with the firmware and unless DJI do something for X8s we will be stuck with it I guess.

 

[robyr1]

Right..so we should to wait

 

[garyshainberg]

Guys, I also have the same problem with the A2 although when I fly the WKM whilst the problem is still there it is much less pronounced, I hope to do some further tests with the "Quad over Quad" mix and see if this helps at all

 

[Carapau]

Ay oop Gary, good to see you here. I tried the Quad over Quad as we chatted on the phont and it didn't do much on my rig so hopefully you might have more luck.