Normal behaviour?

[AlphaZeroOne]

I have been flying UAVs for about 4 years now, purely as a hobby. This was way before the likes of Litchi and AutoPilot were released. I own both apps and have spent many hours boning up on the various means of planning and flying pre-programmed flights. But I have always flown manually and have spent many hours and days getting to feel of the responses of the aircraft to my stick inputs. Then today, I decided to give the Litchi app a test flight. I defined a very local set of waypoints around one of our meadows. Nothing ambitious in terms of height and speed with just one defined POI. Having initiated the flight sequence, it felt odd to see the phantom move away without any input from me. The first flight performed without a hitch, with a very stable flight . On landing I launched to same flight again, interested to see if the video recording would be identical to the first ( I'm planning a landscape video showing the changing seasons over a year). Although the phantom flew the waypoints in exactly the same manner, what I did notice at several points in the flight was a sudden but brief change in the prop speeds and, at the same time, a small but noticeable increase/decrease in altitude. This didn't occur during the first flight and my finger was paused on the flight switch to take control. But all seemed fine. My question is really, is this sudden and erratic increase of prop speed and small change in altitude, normal behaviour for an auto flight or does suggest an underlying problem

 

[Oso]

Was there a gust of wind?

 

[Richard R]

I've flown litchi missions that were several 1000 meters I total length. And reflown missions a couple of times and have never had my bird act as you described. How much change are you talking about? Have you checked the flight logs to see if there was something happening at those points? And did you try flying the mission again to see if those changes would repeat? How high AGL were you flying and did you have VPS engaged?

 

[Steve7777]

I agree in that whenever you re-fly a Litchi pre-programmed mission, it is unlikely that it will be exactly the same as the one you flew before. It'll be very similar, yes, but never exactly the same, owing to (as Oso has already said) a different gust of wind, other changes in weather conditions, fewer satellites connected or maybe differences in the drone's barometric ie: altitude readings..

 

[AlphaZeroOne]

Was there a gust of wind?

The wind was a little gusty but nothing to be worried about in terms of wind speed. I'm familiar with the motors working independently of each other to maintain position. But it was the change in height that was unusual. Nothing dramatic, probably 12" at the most.

 

[Steve7777]

The wind was a little gusty but nothing to be worried about in terms of wind speed. I'm familiar with the motors working independently of each other to maintain position. But it was the change in height that was unusual. Nothing dramatic, probably 12" at the most.

Given the accuracy of the barometer on a P3, 12 inches is nothing... If it happened so suddenly, it was probably just some adjustment to new data received.

 

[Neon Euc]

I wouldn't worry about it to much to be honest. Been using litchi almost a year doing 3 miles all around flights going for 9 mins and I guess now and then the motor will rev up more then it did before. Its like a car... You can go spot on at 50 mph but slow down, do it again and I bet the engine will rev slightly different. [emoji4]

 

[AlphaZeroOne]

Given the accuracy of the barometer on a P3, 12 inches is nothing... If it happened so suddenly, it was probably just some adjustment to new data received.

Thinking about it, that sounds about right actually Steve7777. Also, I use a iPad Pro which also has an inbuilt barometer. Thanks to everyone for such quick responses! I will re-fly tomorrow to see if the incidents are repeated.

 

[Steve7777]

Thinking about it, that sounds about right actually Steve7777. Also, I use a iPad Pro which also has an inbuilt barometer. Thanks to everyone for such quick responses! I will re-fly tomorrow to see if the incidents are repeated.

OK - I'm pleased that you think it might be a valid reason and hope all goes well tomorrow.