Barometer

[quads500]

In many posts, it is said that barometer is very sensitive which can be effected by changing weather conditions and even light. Isnt it effected by the pressure of propellers when we give thrust or vice versa?

[Paul01]

Yes, they are, you should alway cover the barometer with a piece of foam and stick the FC in a case if possible.

[ChavasRegal]

Yes it can be affected by the thrust and prop wash to keep this to a minimum you need to place a piece of breathable foam under the FC where the baro is.

[shaun]

Have to admit always been a bit confused by the term breathable foam!
No doubt just being thick. Anything more specific or examples? Type. Thickness.

[Paul01]

Stick the piece of foam your thinking of using over your mouth, if you pass out don';t use it :-)

On a serious note foam around 10mm think is about right, and if you can blow air through it then it';s the right kind of foam. Dark foam will help block light out as well, as some barometers are sensitive to light

[Hands0n]

I have had good success with the dark grey foam typically used to pack PC hard disk drives for shipping.  There';s nothing special about it except it is quite firm, light does not penetrate (tried using a Cree 700 Lumen torch, nada) and breathes quite freely.  That makes it good for all but being in strong propwash.  You might need to add further shielding around the FC itself.

Anecdote: A friend has a similar multi-rotor to mine (his is quad mine is hex) and the APM 2.6 FC is mounted very similarly. He gets more propwash over the core of the multi-rotor because the arms are a bit shorter, props closer to the core. Flight modes that use the barometer resulted in vertically jerky flight. Adding solid foam around the FC solved the problem.  Removing it for control test purposes saw the jerky flight movement return. Refitting the solid foam saw the "fault" clear.

We believe that the propwash pressure waves were entering the APM';s FC via the long row of upward facing pins A0 - A15.

[shaun]

Stick the piece of foam your thinking of using over your mouth, if you pass out don';t use it :-)

::)