P3P Barometer

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Hi All,
My P3P has an annoying habit of physically dropping altitude, meaning the aircraft will slowly lower it self down but the altitude onscreen remains steady. I compensate by climbing, which registers onscreen, but it will not maintain a steady altitude while hovering. An example is: I take off in my yard and hover about 6 feet off the ground, mainly to test my batteries, at the end of a 20 minute hover, the aircraft is still only 6 feet off the ground but my constant correcting by pushing up on the left sticks shows I'm at 30 meters onscreen. I've tried many IMU calibrations (both cold and warm temp) and the calibration always completes normally but this issue never goes away. Do I need a new barometer???
 
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Here's the end as well as a battery and temp reading at the end.
 

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The Z has always had a mod of 1.0. This AC has had 2 minor crashes. No damage other than props. Could the IMU damaged?
 
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To further clarify, the AC behaves perfectly in normal flight, vertical height shows climbing and descending when done purposely with the sticks, but hovering it slowily descends, at least at ground level, cannot confirm whats happening when i can barely see it. I wonder, does it always have a gradual descent for some correctable reason?
 
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BP changes very slowly. Over a 1 day span, it may change by less than 1kPa providing there is no major atmospheric changes such as a warm or cold fron moving through. Major changes during a 20 minute flight is very rare. I often see my altitude at landing is several feet lower or higher than takeoff (usually lower, for some reason). I haven't tried the prolonged hover test.
 
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I had a similar issue on my P4 caused by an accessory gimbal guard, which attaches to the landing gear under the camera. The bottom sensors got confused seeing the gimbal guard, resulting in a yoyo effect when at altitude in a hover. It flew fine, but couldn't keep a steady altitude in a hover. I'm wondering if you recently installed a gimbal guard in the wrong place on the landing gear.
 
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I had a similar issue on my P4 caused by an accessory gimbal guard, which attaches to the landing gear under the camera. The bottom sensors got confused seeing the gimbal guard, resulting in a yoyo effect when at altitude in a hover. It flew fine, but couldn't keep a steady altitude in a hover. I'm wondering if you recently installed a gimbal guard in the wrong place on the landing gear.
No I have no accessories at all attached. No prop guards, nothing.
 
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I would think that VPS would stop it from descending too close to the ground but it doesn't. It gets very close to the ground, close enough that I manually correct by climbing, to be honest I havent let it actually touch down so I'm not sure if it would.
 

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I would think that VPS would stop it from descending too close to the ground but it doesn't. It gets very close to the ground, close enough that I manually correct by climbing, to be honest I havent let it actually touch down so I'm not sure if it would.
I’m wondering if the VPS is even working...
 
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I’m wondering if the VPS is even working...
Well it does correctly show the altitude from the ground although I've never really found it to help much for stability, indoors or out. Even with a clear pattern for it to "look at" it wanders around. Normally I keep it turned off as I've read the ultrasonic sound it creates can annoy dogs and other wildlife.
 
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Clearly this isnt a common issue with P3's and its not really a big deal. It's only noticeable and annoying at very low altitude which is not usually where we fly. Was just wondering if anyone has had this issue and knew of a fix.
 

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