My Phantom 4 is tough!

[John Locke]

Just today I notice an altitude inaccuracy from start to finish, so I need to do some more testing to figure it out just what it going on.

When I launched a Litchi mission this morning, I had the first way-point set at 10'. When I enabled the mission, the craft went to the 1st way-point set at 10' AGL (I was on a cliff), and it did indeed start the first way-point at about 10' high, as expected. As I flew the mission I cancelled it. I wasn't happy with the route, so I started flying manually around the area collecting video for about 15 minutes. However, when I returned, flying manually, the elevation data on the screen got skewed somehow. When I returned to the original way-point #1 (manually flying to that location, very close to right above my head), instead of showing 10' high, it showed 50' high, when in reality it was only 10' high. Since it was 40' off, I'm thinking if I had finished the mission, during the return leg to the last way-point set at 10', it would have run into the cliff I launched from. This was 8am, it was about 85F, and getting warmer. I'm wondering now if heat skews the barometer accuracy.

I had never noticed this elevation anomaly before because I always flew WAY ABOVE ground level 150' or more, too high to discern any elevation inaccuracies of 40'. Has anyone else flying Litchi missions noticed this problem?

 

[Steve G]

Talk to Dirty Bird. From what I've seen, he's a master of the Litchi waypoint missions. He might be able to give you some insight.

 

[andre renaud]

After having some incidents on landing my P4, I realized that the three times it happened and wanting to stop everything in panic, I pulled both sticks towards me, instead of pullind down only the left one.It is a pure reflex.So, my suggestion for DJI is to apply this panical reflex on the next generation of phantom.

 

[John Locke]

After having some incidents on landing my P4, I realized that the three times it happened and wanting to stop everything in panic, I pulled both sticks towards me, instead of pullind down only the left one.It is a pure reflex.So, my suggestion for DJI is to apply this panical reflex on the next generation of phantom.

I thought DJI removed the two stick CSC 4-6mos ago (new firmware), in favor of "left down" while "pushing RTH button" for immediate shutdown. Yes, the "left stick down only" works too, but it takes 3 seconds to shut down, time needed to confirm it's on the ground and not moving. If they didn't remove the two stick CSC, they should since it's got to be executed perfect when you're on the ground to avoid the craft from tipping, ruining props.

I sure wish DJI would let us adjust the idle speed. In the slightest wind it's spooky to land because the idle RPM is slow fast it wants to tip, so I always hand catch. The P3P idle speed was lower, it didn't have this problem.

 

[Dirty Bird]

I've never experienced anything like this in my Litchi missions. One thing I've been particularly impressed by is the consistency not only between flights but also between aircraft. If you go through my public videos you'll see routes like "Harbor Shot" & "The Baltimore Run" are consistent flight after flight. I flew the route Saturday with my P4 at around 94° & it still worked fine. Thinking your situation may have been a one off anomaly.

Just today I notice an altitude inaccuracy from start to finish, so I need to do some more testing to figure it out just what it going on.

When I launched a Litchi mission this morning, I had the first way-point set at 10'. When I enabled the mission, the craft went to the 1st way-point set at 10' AGL (I was on a cliff), and it did indeed start the first way-point at about 10' high, as expected. As I flew the mission I cancelled it. I wasn't happy with the route, so I started flying manually around the area collecting video for about 15 minutes. However, when I returned, flying manually, the elevation data on the screen got skewed somehow. When I returned to the original way-point #1 (manually flying to that location, very close to right above my head), instead of showing 10' high, it showed 50' high, when in reality it was only 10' high. Since it was 40' off, I'm thinking if I had finished the mission, during the return leg to the last way-point set at 10', it would have run into the cliff I launched from. This was 8am, it was about 85F, and getting warmer. I'm wondering now if heat skews the barometer accuracy.

I had never noticed this elevation anomaly before because I always flew WAY ABOVE ground level 150' or more, too high to discern any elevation inaccuracies of 40'. Has anyone else flying Litchi missions noticed this problem?

 

[andre renaud]

thanka to you, M.John Locke, for your fast and pertinent reply.I think you should have your own web site... After seeing some of your videos, and for your very impressive knoledge in the drone world,i would be honored to subscribe to your website

 

[John Locke]

I've never experienced anything like this in my Litchi missions. One thing I've been particularly impressed by is the consistency not only between flights but also between aircraft. If you go through my public videos you'll see routes like "Harbor Shot" & "The Baltimore Run" are consistent flight after flight. I flew the route Saturday with my P4 at around 94° & it still worked fine. Thinking your situation may have been a one off anomaly.

It's not Litchi, it's my craft barometer. I started another thread explaining the GO app has the same anomaly. My next test is to get a barometer app on my phone to measure the atmosphere pressure before and after flight to insure it's not being caused by changes in the atmospheric conditions. Longshot.

 

[m0j0]

I'm slowing down and taking more care..

Cheers Eric

Sent from my iPhone using PhantomPilots

Why did you fly backwards? Also if you are going to go off at 40mph why wouldn't you have it up high enough to avoid a collision with trees, fences, poles etc. lol. I will tell you what though the video was really clear.


Sent from my iPad using PhantomPilots mobile app

 

[kirk2579]

What I was getting at, is that reading the posts over the last couple of months with the OP saying along the lines of "Bird Crashed any ideas why?". Then people posting the reason that they were "flying backwards into a wall", or they had their "RTH altitude set too low", or whatever. The reason they crashed was that they had made an error, whether they realised it or not.

EricThViking, the OP for this thread, openly admits he cocked up when using Sports Mode for the first time, and has taken the time and effort to let us know. Giving a few of us a laugh, but reminding people that it is so easy to make the simplest of mistakes.

So it wasn't about blame, it was just surprising to see someone start a thread saying look at the stupid thing I did, which so many of us do.

+1

usually its: I crashed bla bla bla ....,
how do I get my warranty repair!

 

[etr102]

I had a close call when landing today. I used the RTH auto-land, and (as usual), the drone came down within a few feet of 'home'. Anyway there was a garden right next to the sidewalk I was landing on and I must have misjudged but on my way down my props ended up clipping a small bush in the garden. The drone's flight was unaffected and made a safe landing while giving the bush a trim. There are no cracks or any visible damage to the prop blades that I can see but should I switch props just to be safe? As long as there's no cracks or anything are they generally good to go or would you guys swap em out?

 

[johnbowen]

Can you clarify? Isn't the ground your take off point?

That was an unbelievable save.

I think his point is that litchi maintains a programmed height as it flies between waypoints. That height is based upon the height measured upon take off from the ground height, relative to sea level.

If u took off from 500 above sea level and told it to maintain 50 feet than it would maintain 550 feet feet above sea level but indicate an AC flight altitude of 50 feet. If the terrain remained flat, no issues.

if the terrain under your AC were to rise in altitude, than your AC altitude would decrease, relative to the terrai, despite maintaining the same flight altitude.

Think about it this way; GPS and measured barometric pressure don't know the height of the ground under your AC, on;y height above sea level. That's why military aircraft use ground terrain radar to maintain a certain height above terrain