Hello from Beijing, watch my tricopter/APM2.5.2

Hi, I watched the flitetest youtube channel for a while, and was encouraged to build a tricopter myself. (The rcexplorer.se plan from David)

I don't have those fancy machines so I did the "cut" by hand using knife!

I'm using SunnySky 2212 motors, and installed them with Zip-ties. 

I have a quadcopter with APM installed. I love the APM so I have it on the tricopter too.

The above pic shows the "legs" are too short, that the battery touchs the ground. As I have to knife cut the board myself, which I hated, I used wires to extend the clearance. (You can see in the video)

This video shows how it flies in Loit mode in low altitude. It's the default settings - I never tuned any P.I.D.

My tricopter has APM2.5.2 on it. The firmware is 2.91b.

It flies super well on Stab mode. When hovering, the throttle stick is around the center position.

Then switch to Loit mode, it suddenly reduces the height a little bit and immediately increase the throttle to regain the altitude. I didn't tune any P.I.D, so I'm satisfied with it. This is the most case, about 50%.

However, on other 50% case, it will increase or decrease altitude rapidly! The decrease is scary - It almost hit the ground some times.

This happens on RTL mode too. Most case, it climb to 30meters before returns home. But it often returns without climb (lower than 30m). And when flying back home, it often flies lower and lower then hit the ground!

I wonder the barometer failed. However, when it climbs or descents, no matter controlled by me or by itself, it shows on the OSD or MP that the altitude number is changing accordingly... It just cannot maintain the altitude.

Somebody told me to replace the barometer, and some others suggested me to upgrade the firmware to 3.0beta. I don't want to try the beta since I heard it's not compatible with the minimOSD. 

I finally solved this problem. So here's the TIP:

Just remove the foam tissue covered on the barometer, the problem never comes again!!!

I think this applies to those APM boards with the case on them.