M2P "Extra Payload Detected" at high altitude

[Chiuki]

Asking for help:
New behavior for stock older drone (Mavic 2 Pro) (latest FW, latest FC, latest Go4 on Smart Controller - reflashed firmware, same behavior)
I fly to inspect avalanche fences, forrest health, potential rockslides/avalanche and mountain construction sites for agencies in the italian alps. One drone I use is the M2P. Altitude and location can be several KM from home point and several KM in altitude, though rarely more than 50m AGL during flight (steep mountain incline)
It may be coincidental, but I just got MAS Endure props (i've been using stock and MAS Stealth props for hundreds of flights, no issue). Also have a new battery (6 months), which until now has been fine. Again, this may be coincidental.
The new behavior is an "Extra Payload Detected" message appearing - usually when the drone is near the mountain peak. I've occasionally seen the 'High Winds" message, but I try not to fly in those conditions.
The Payload message triggers a throttling of performance. Ascent & descent are capped at 3m/s and horizontal speed is capped at 30km/h. I have changed the sport mode parameters to be higher, but these settings are ignored.
I'm not able to understand the DAT/TXT files enough to understand exactly what is going on. I see battery errors around the time the message appears.

354.907 : 20227 [L-NS][AHRS] Bad sample tick measure or recapture signal: 0.005000
362.393 : 20602 [L-BATTERY]get cell voltage time out!

589.663 : 31989 [L-BATTERY]flylog_data_report_prepare error, ret1=0,ret2=-6,ret3=0

Now, the older battery and original props are also triggering this Warning/error and performance throttling.
Where can i look to see what's triggering this error and correct whatever is causing it. Being able to move quickly at these distances and altitudes is critical for safetly.

 

[FLDave]

You don't need to understand .txt files; just upload to your AirData account and the information will be presented in an understandable manner. It's a good idea to review this information on a regular basis BEFORE you have a p;roblem.
As for altitude, check the specs in your user manual. The drone firmware will detect when the drone is working too hard to flight or ascend.

 

[Yorkshire_Pud]

I would be inclined to post a suitable .txt and DAT here and see what folks make of them.

One question, is the drone's firmware hacked? As far as I know the drone should be limited to a height of 500m above the level of the takeoff point, your post seems to suggest you can reach 2000m+ above the level of the take off point.

 

[Chiuki]

I would be inclined to post a suitable .txt and DAT here and see what folks make of them.

One question, is the drone's firmware hacked? As far as I know the drone should be limited to a height of 500m above the level of the takeoff point, your post seems to suggest you can reach 2000m+ above the level of the take off point.

I have a uploaded my CRO license / EASA STS-01 VLOS to DJI which unlocks most limitations. Also, I don't see any reference to the error on airdata.

 

[pchaps]

I suspect that what you are encountered is density altitude in that the aircraft is losing thrust due to the "thin" air at high altitude. For example, this is why a high peeformance military helicopter cannot do rescue on Everest above a certain level. In a sense, the standard aircraft may be perceived as "heavier" by the drone's flight control system, the 'brain,' It may sense that the thrust is not as effective and therefore 'assume' that the aircraft is heavier. Thats my hypothesis,

For Everest rescue where they can, such as the daring rescue of Beck Wethers at Everest, they took the seats and all they could out of the Nepali jet turbine helicopter to fly at altitude. I think they even jettisoned rescue gear. Therefore, any efforts to reduce aircraft weight would help.

The high wind beast is the old TurboAce Matrix with 15-inch props (quad) very old school and a pain but effective. I have to wonder if it would be a champ at high altitude. Requires a separate controller like Fatuba and is frustrating to use, but wow can it fly!

 

[Chiuki]

After 100 tests, it's obvious that the issue is the Master Airscrew Endure props. Error was triggered 2m off the ground with zero wind at 850m above sea level. No other props cause the error, regardless of battery age or state.
Props would be fine for slow, low-altitude cinematic video since the performance and reaction are slowed WAAAY down, almost like tripod mode.

00m 16.4s

P-GPS

9

9.9m

7.2m

0.1m/s

1.3m

99%

16.58V

4.149V

4.149V

4.148V

4.137V

0.011V

100%

Extra payload detected. Flight performance will be affected. Fly with caution.

00m 43.7s

Sport

11

56.6m

7.2m

0.6m/s

2.9m

98%

16.43V

4.114V

4.113V

4.113V

4.092V

0.021V

100%

Reached maximum speed of 0.6 m/s.

 

[REStewart]

Looks like pchaps hit the nail on the head. Seems to be a clear case of density altitude. The drone is working super hard to maintain level thinking it has extra weight. The different props were just enough different to make the difference. You have an amazing job with your drone....

 

[Chiuki]

Looks like pchaps hit the nail on the head. Seems to be a clear case of density altitude. The drone is working super hard to maintain level thinking it has extra weight. The different props were just enough different to make the difference. You have an amazing job with your drone....

I'm certain you're both right, even at an in-ground-effect hover at .5m I get the error. The difference in weight between the stock props (which never gave any error, the MAS Stealth props (also never gave the error), and the MAS Endure props is just over 10g per set - apparently just enough weight (and larger surface area) to convince the ESC to throttle performance. (I just synced my DJI account with my Airdata account and now I see the ESC error that appears when the AC is at high altitude/thin air "Not Enough Force/ESC Error". My flawed logic is that wider props would help in thin atmosphere, but that doesn't exactly seem to be the case. Seems the extra weight causes more problems that the wider props solve.
At any rate, MAS have refunded all the money without my asking them, and told me to keep the props.
Thanks all for the advice.

 

[Chiuki]

Looks like pchaps hit the nail on the head. Seems to be a clear case of density altitude. The drone is working super hard to maintain level thinking it has extra weight. The different props were just enough different to make the difference. You have an amazing job with your drone....

Side note to REStewart: Yes, I enjoy the job! We use a combination of helicopters, drones and climbers. The helicopters are expensive to run, and climbing is a sloooow option, but a Surveilance or LiDAR Survey drone is a lot easier to get to the site and a heck of a lot cheaper.

 

[pchaps]

Side note to REStewart: Yes, I enjoy the job! We use a combination of helicopters, drones and climbers. The helicopters are expensive to run, and climbing is a sloooow option, but a Surveilance or LiDAR Survey drone is a lot easier to get to the site and a heck of a lot cheaper.

If the props in question have a lower pitch in the their design, it would be opposite of what you want in a high density altitude flight environment. The lower pitch or tilt angle of the prop reduces thrust. A prop with higher pitch would grab and move thin mountain air more aggressively and be your ally. Keep up the great work. For custom built uUAV, we can select the pitch of the blades and they are noted in the manufacturer's specifications.

 

[pchaps]

The other specification for the sUAV in high altitude density environment is an aircraft with a comparatively higher "thrust-to-weight ratio." Greg from Pilot Institute did a comparison in one of his videos. The results were uplifting

 

[Chiuki]

I tried to find the pitch specs for both types of MAS props, but wasn't successful. But if it's true, what you're saying is exactly right and would explain it. I assumed that because they have a larger surface area and (again, assumed because I couldn't verify it) the pitch was the same, thus should give more thrust with less energy. In some situations, these props give smoother flight and slightly longer flight times, but sacrifice speed and agility.

Another design flaw has appeared in further testing - the tips of the rear props lightly brush the rear side sensor border and bend the tips. I will sand the prop tips down and see if it continues.