8000 ft limit?

[lemontea]

Hi Brad,

My video in post #13 is the highest I have been. Launch from 3250mtr and I went up another 50 mtr. Just under 11,000 ft in total.
I didn't notice much of a difference compared to flying at sea level.

Looking forward to your ccc.
Thanks,
Rob

 

[robcooper2001]

The max altitude of 8000' ASL is indeed sensed and the motors will not start above that point. Yuneec will provide modified firmware to people who need to a launch point above that altitude. I believe that limit was placed because flying at altitudes higher than 8000, require special care by the pilot. With "thinner air" there is much less lift. Wind becomes a major factor and VRS more likely.

I think you need to fill in a form from the CAA or local authority with a license number...(?)

 

[Steve Carr]

There were many reports of the Q500 entering VRS with carbon fiber props installed, most occurring at high altitudes. Many of the videos on Youtube are labeled "Wobble of Death". VRS is the primary reason for limiting the max descent rate.

 

[Arkansas Pilot]

I personally, and respectfully, disagree with PatR. It is my view that VRS can occur with multirotors if the right (or wrong depending on how you look at it) conditions prevail.

When an aircraft is hovering, it induces a flow of air through the rotor discs in the same way as a propeller does in a fixed wing aircraft. The inner sections of the rotor blades have a greater angle of attack to even out lift across the blades. If the aircraft descends, then, the external airflow will oppose the induced flow generated by the rotors. The blade roots will have their relative airflow adjusted by this external flow caused by the descent, giving an effective increase in the angle of attack.

At the blade tips, the vortices recirculate and intensify, aided by the external airflow. This causes an effective decrease in the blade angle of attack, and therefore lift. If the process continues, the blade will stall at its root as it reaches its critical angle of attack, and the blade tips will be producing less lift due to the recirculating vortices. It is at this point that it can be said that the aircraft has entered VRS. Note that the vortices do not form in a symmetrical fashion so the aircraft may move in all three axes in an unpredictable manner.
Reference: Rheinmetall Remote Pilots Course (Theory) Aide-Memoire (RTP UK) Page 31.

I agree with PatR that multirotors are less likely to be effected by VRS given that we have opposing rotation rotors, but certainly not impossible given the right conditions.

With respect to you PatR.

I must agree with you when it comes VRS and drones. I own several Phantoms, P2,P3,P4 and Yuneec H. I have seen the drones I own get crazy if I come straight down and hover to long in one place. In order to correct this problem, I would fly in at a low angle and land as soon as I could which seemed to solve the problem with P2 and P3's. It seems that DJI may have corrected this with the P4. Regardless, I try to come in at a low angle and then land. The Mavic and Spark are of course different and I think that due to their smaller size, including the blades, for the Mavic has it's auto land and it may be due to it's programming which makes it wait for stability. Just a thought on my part.