I have noticed upon touchdown of the craft I hear to a greater or lesser degree a revving up of the

motors before idling down.  I have gone to minimum throttle at 6" above ground and this still occurs.

I had a flipover recently due to this plus some light wind.  I have been told to recalibrate the ESC

but I have heard this momentary rev up since then.  Sometimes it is barely noticeable and some-

times it is very noticeable.  Another problem I have had recently is for the craft to switch to the

LAND mode on its own.  One time I noted the battery at 50% and another time at 30%.  Since

then at normal, below 20%.  Any comments along these lines would be greatly appreciated.

Thanks for reading and HAPPY FLYING.

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Replies to This Discussion

I'm having the same issue. When it touches down I even try to disarm and it still revs uncontrollably. I've even had it lurch forward like it was going to take off again. Ive calibrated the esc's numerous times and it doesn't seem to help. I'm beginning to think it the radio.

I have found that after autonomous missions that it winds down nicely if I leave it in "auto" mode. I stick dwn/left and it switches off. I find that if I switch to standard mode I experience the revving. Just my experience...

Wow, I don't understand, how I could missed that. It is exactly as you say.

So far I had three flipovers, everytime with broken props and it was everytime after landing in stabilize mode after auto mission.

How did you solve it? Are you putting land as part of mission? Or is it, for example, possible to switch to stabilize after mission and then land by RTL?

Thanks, Tomas

I noticed the rev up on landing when doing a disarm as well.
I though it was due to landing in the grass and having a foot dig in.
The attitude control would then try to compensate and with the foot sticking
Causing a rev up as an attempt to level the "angry bee"

So maybe it is not the planting in the grass.
I was landing slow and near the ground would encounter a slight drift so I went to a little faster landing. Maybe better, about 10 tries to see what happens, not sure, but any horizontal motion in grass does result in a tip.

I did almost flip once and now wonder why as it stands up my neck hairs when it happens.

I have also had the land mode switch on with all good....battery, RSSI, distance etc.
So I practice going to alt hold then try loiter till i get it together.

Need to look at the Telemetry closely for this one.

My first ever flights were above a solid surface and I landed, went to minimum throttle let it spin
down and did not notice the rev up when doing a disarm.


Hope to find out what is happening

I've had the most success appending take-off and landing waypoints when send mission file. I find it shuts right down on landing when I use that scenario. It took me a while to learn you can still guide and control the Iris while in Auto with your standard controller. Usually I will make minor adjustments to my landing spot. I've had a few instances where someone unknowingly walked under the landing and I flipped the RTL switch. It climbs again then lands. 

Same or similar issue.  I was starting to wonder if I wasn't disarming correctly.  Interesting comment above re behavor after an auto mission. Very often I run an auto mission, then do some manual flying in Alt hold or Loiter.  Gonna give it a try without ever running an auto mission. 

When landing in an altitude assisted mode (like AltHold or Loiter), it uses a landing detector to detect that it is on the ground. Right now, it takes a couple of seconds to detect that it is on the ground. Supposedly in the next firmware update, the landing detector will detect a landing more quickly. Instead of trying to disarm as soon as you touch down, try this. When you land, just hold the throttle all the way down but don't give it any rudder. After a second or two, you will hear the motors go from a faster idle spin to a slower idle spin (basically you will hear the motors spin down). Once that happens, it has detected the landing. You can now disarm without fear of it spinning back up aggressively. Give it a try and see if it helps.

are you saying that you've never witnessed this?  I "try" to disarm after motors are at idle.

The only time I ever experienced it is when I would try to disarm immediately after landing in AltHold. I would give it left rudder to disarm and the motors would spin up. But once I realized what was happening, I simply held throttle low until the Pixhawk detected it was on the ground (motors spin down all the way) and then give it left rudder to disarm and never had the problem again. Another way to avoid this is land in stabilize mode. Stabilize mode does not assist in holding altitude so you won't have this problem at all as the motors completely spin down at min throttle (even if you are 100 feet in the air). I've even tested this by landing on my car hood (very sloped surface). When I touched down, 2 of the legs were on the car hood while the other 2 remained in the air as the quad kept itself level. After a second or 2 just holding throttle low, it detected the landing and the motors spun down and the other two legs touched down. Then I was able to disarm without any issues.
However if you still have this problem trying to disarm in Stabilize mode (not STD mode as 3DR labels AltHold on the Iris+ radio), then you might have a problem with the radio. Do you use the stock FlySky radio and have you changed any of the default flight modes in Mission Planner?
First thanks. For your comments. Everything is stock and software unchanged. Won't be able to do more testing til Tue or wed. Will
Use stabilize. I thought this revving had to do with autopilot. After
Half a dozen landings yesterday if the craft is not level or the surface
Is not level, at touchdown, that the revving is more pronounced. I
Thought stabilize would interfere. I will comment wed if its not to
Windy.!

Hi,

I had this problem on old 3DR IRIS in Stabilize mode, I didn't changed anything in mode settings and used the FlySky radio. It happened 3 times, always after auto mission (but I have also did successful missions and landing in stabilize mode).

I will try to find logs.

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