New H Pro RS - Poor landing - Cold Weather?

[Dougcjohn]

Weather finally got up to mid-teens with mild wind... previously performed all Firmware Updates, successful bond RC & CGO4, the ECU & Gimbal calibrations inside and warm. Couldn’t get a good compas cali in driveway, so tried an open field... in 3ft snow & -16 Windchill. After 3 failed attempts, figured it was maybe the 60 second time limit and not the Cali reading causing failure so spun the H a bit faster and got the melody and positive lights.

Returned to home to warm hands & H, then tried 1st flight Hover at end of driveway with 17 Sats indicated available (Normally able to fly all my DJI models from drive without issues). The H started nicely, spun up the props and lifted smooth. Had a mild drift with wind to the West (left) but figured I’d explore that later on a warm day. Today was just to verify flight operation.

Took the H up & down, Lf & Rt, full 360’s, etc. Took it up to 50’ to test landing gear. No-Go... Rt leg appeared to try, but left leg solid. Cycled the landing Sw without success. Is there a way to test landing gear on bench?

Hovered down to land... skids would touch then slightly begin struggle & bounce and initiate a tip over to Left. Twice I aborted and lifted back up... verified all switches off: Landing gear and Obstacle Avoidance. Flight Sw Middle for angle mode / purple light.

On several proceeding landing attempts, pressed and was holding Kill switch... but before killing, started to lean to left and I aborted before prop strike.

Each attempt, would fight to get the H to touch down... then would start leaning.
Tried holding kill switch while near ground, just touched down when motors stopped... was in a lean with Rt skid light... close to tip over.

Restarted RC and H... lift off smooth, landing touched down smooth... then suddenly lifted off. Brought it back down, and same difficulties. Tried a kill Switch while hold Lf stick down... in last few seconds, tipped over and prop strike on two props... causing motor stall.

Questions: Is the cold causing poor landing behavior, did attempting to cycle landing gear make it appear as gear up? Poor landing behavior is new to me, normally my experience is when near ground or at touch down, smooth power down.

Any suggestions would be helpful,

 

[Steve Carr]

Is the cold causing poor landing behavior

It sounds very much like the right stick is not returning to zero when the stick is centered. Turn on the ST16 only, and test the sticks very carefully in Hardware Monitor. Move the sticks slowly and watch the response. The reading should go to EXACTLY zero when the stick is centered. And it should do it every time. If the right stick doesn't return to center exactly, it will cause the drift you see and also make landing more difficult.

You can check the landing gear inside by removing the camera and props. Turn everything on and then turn the H upside down. Cycle the gear several times. It's common for the gear to get jammed during shipping and it will usually un-jam using this method.

 

[Dougcjohn]

Steve, prior to 1st flight outting, I did verify sticks & switches were correct & sticks zero. I had even examined how to change the curve... and returned to stock.

On the sticks, it was a little twitchy L&R, but smooth going Fwd&Aft. Mild stick L&R would tilt the H similar to a full push.

Although, you mentioning recalls while compass Cali, laying RC down a few times got snow in the switch cups. I blew it out, but possible had little ice as friction in gap between stick & cup. But I would think that would cause any direction, not just left.

I’ll double check the sticks too. Are these often a bit off new?

 

[Dougcjohn]

Verified Sticks in Hrwd Monitor as zero for both.
The upside down Landing gear test showed Rt no movement and left moves about 1-2" then returns to down.

I’ll break it open to inspect.
While inside for 1st time, any other areas to check too?

 

[Steve Carr]

With the landing gear just remove the two screws on each and they will slide out. Sometimes when they are new, loosening the 5 case screws a half turn and reinstalling them to test will get them working.

If you are absolutely certain the sticks are operating smoothly with no signs of sluggish movement, then the next step is to do the ST16 calibration.

 

[Dougcjohn]

Landing gear corrected... one servo’s gear shaft was pinched, the gear shaft & bearings were misaligned, wouldn’t free until split servo case, remove gear asmb and re-asmb. Now both have a slight bit of play static and retract nicely.

The drifting & twitchy behavior may have been related to the Real Sense module within advance not being checked and turned on. Even though object avoidance Sw not turned on, doesn’t the real sense provide stability sensors or replace sensors.

If weather permits, I’ll verify tomorrow.
Thanks for the assistance!

 

[Steve Carr]

Drifting is nearly always the result of a problem with the right stick sending a signal to the FC. Otherwise it will hover within a meter or less with a good GPS fix. The RealSense turned off would not cause drift.

Good job on fixing the landing gear. They can take a beating in shipping.

 

[tcwhite]

Just an FYI to your cold weather statement. I fly a lot in - degree weather with snow falling. It hasn’t hampered my H at all. Great job to you on fixing it.

 

[Dougcjohn]

Today’s weather was 2 F, wind chill -12... moderate wind, but a great sunny day!

I rechecked & calibrated the sticks to eliminate the possible cause. Also softened the initial travel curve of Rudder & Aileron for start of movement.

The drift was not apparent... very slight a few times. Overall flew very stable and smooth. The landings was more like expected, hovered down to touch down and remained down. If Throtle was held down, the props stoped. Performed multiple landing, all smooth.

With 1st battery down, went inside to warm up hands for short time. Inside for 8-10 minutes, back out with 2nd battery, did a 12 minute stable flight, but the landing was not smooth like previous day... struggled to idle down, used kill switch. Tried it a 2nd time with same results.

I was thinking the issue may be moisture from cold to warm on circuits from when bringing H or RC inside for short 8-10 minutes. Probably not enough time to dry moisture off circuits.

I’ll test again later during week. In comparison, the Mavic performed without issues, although goes into a landing mode when hovered down to 6” with T-stick held down. A feature that would be useful on the H too.

Initial observations of first few flights, the prop sound is Great... very distinct sound wash departing & returning! The gimbal adjusts for steady video, but the prop dish tilts more than expected for mild movements, will need to get used to the visual. Overal, a smooth craft that will be a pleasure learning the H’s unique characteristics and multiple cameras.

 

[Dougcjohn]

Just an FYI to your cold weather statement. I fly a lot in - degree weather with snow falling. It hasn’t hampered my H at all. Great job to you on fixing it.

Thanks for the info, eases the thought if too risky below 32F.
Do you experience any sub-freezing landings where it struggles to idle down, then off? You fly while snowing, any moisture problems?

Another thought, the Turtle-Rabbit mix slider. Watching the curves, throttle doesn’t go below 20% on “turtle side” and 0% on Fast side. I don’t recall where I had this slider, maybe 1/2 travel. If throttle was down to 0%, thought that might improve the landing throttle down.

 

[Steve Carr]

Another thought, the Turtle-Rabbit mix slider.

Just curious.....did you have the slider at the midpoint when you did the ST16 calibration?

I flew in early Feb on a morning when it was -3 deg F. Went thru 4 batteries and no issue with landing. If it's windy or if I'm landing on a slope, I just hover 8-12" above the ground and press Big Red until it lands and the motors stop. No damage to props even is it does tip and it won't matter if it's in turtle or rabbit.

The flight characteristics of the H result in jump starts from hover. That is probably what you see as twitching. It looks rough but the video seems to always be smooth.

Sounds like you've made good progress curing the drifting.

 

[Dougcjohn]

Just curious.....did you have the slider at the midpoint when you did the ST16 calibration?

I flew in early Feb on a morning when it was -3 deg F. Went thru 4 batteries and no issue with landing. If it's windy or if I'm landing on a slope, I just hover 8-12" above the ground and press Big Red until it lands and the motors stop. No damage to props even is it does tip and it won't matter if it's in turtle or rabbit.

The flight characteristics of the H result in jump starts from hover. That is probably what you see as twitching. It looks rough but the video seems to always be smooth.

Sounds like you've made good progress curing the drifting.

Yep, sliders half way by guess 1st time and then by tone after confirming the tone was 50% in the hardware meter views. That's where I noticed how the slider Turtle-Rabbit mixer effected the percentage of throttle scale.

The cold I'm not so focused on now, you and others have indicated not a concern. I'm more questioning the moisture on short warm ups... similar to glasses that gets on circuit boards. When you do your multiples batteries in cold, does H or RC get warm between batteries or you bring another battery from pocket or truck?

The twitchness I think was corrected with the drifting, I mainly just notice the large prop dish tilting alot... compared to quads I'm accustomed. But doesn't effect video, gimbal handles all the movement... it's just a visual thing I'm not used to seeing.

 

[PatR]

Chris,

With both the 480 and the 920 you'll want to hold the throttle stick down and keep it down until you disarm the system and the props come to a stop. Failure to do that introduces the possibility the throttle stick might be suddenly released with the motors running at "idle". A suddenly released throttle stick will spring back to center, causing the autopilot to "think" a throttle up command had been generated. The result is an aircraft the unexpectedly rises above the ground and if other stick inputs are unintentionally being generated by the operator there will be a roll over. The 920 is less prone to this than the H but there's no reason to introduce unnecessary risk, so following the same throttle procedure with both aircraft types minimizes risk.

When flying in really cold temps we need to consider that warm air will have moisture levels much higher than cold air. In sub freezing temperatures the air can't maintain a lot moisture in suspension as that moisture condenses, freezes, and falls as snow. The air inside your warm home usually has a much higher humidity level and when the aircraft is taken from house to outside that moisture can condense on components and freeze. The question is where that freezing process occurs. It could be on an electrical board, landing gear motor, gimbal motor, transmitter potentiometer, etc. We don't have a way of knowing.

Keep your batteries warm until they are to be used. Inside a warm car, inside a warm "cooler" or inside your coat along with a chemical hand warmer. The H will warm up during use but internal temperatures can fall quickly after a flight while performing a battery change. Something I haven't tried, but have considered, is taping a chemical hand warmer pack to the underside of the aircraft to assist elevating the system temperature. An anomaly I've experienced during flights in 10*F to 15*F temperatures is "sticking" of the gimbal during pan rotation. It was only brief and minor but something that has never happened during warm weather. In all other aspects both my H's have performed normally, although with reduced flight times, in operation during sub freezing temperatures. The lower the temperature the lower the flight time.

 

[tcwhite]

Thanks for the info, eases the thought if too risky below 32F.
Do you experience any sub-freezing landings where it struggles to idle down, then off? You fly while snowing, any moisture problems?

Another thought, the Turtle-Rabbit mix slider. Watching the curves, throttle doesn’t go below 20% on “turtle side” and 0% on Fast side. I don’t recall where I had this slider, maybe 1/2 travel. If throttle was down to 0%, thought that might improve the landing throttle down.

I have not had any problems not to say I won’t some day. I have not seen any moisture problems and even upon landing back I have not seen and noticeable water spots. Could be due to light powdery snow not able to make it to the craft with all the wind being generated by the props. I don’t necessarily suggest anyone doing it but sometimes I like getting a good snowfall video.

 

[Dougcjohn]

Pat,
Roger, on the Holding throttle down. I was holding down waiting for the props to stop... while waiting it spun back up on 2nd battery.... again, 1st battery landings were smooth.

Actually I think that's pretty cool how the Yuneec system stops the props and motors continue. I'm used to landing equates to full motor off requiring a new motor start action for liftoff. In hindsight, I may have relaxed sticks... I doubt it, but possible... I am known to a few "senior moments", my Wife claims.

On the moisture, my question was taking sub-zero cold hardware: RC & H back indoors; which certainly causes moisture to develop on components inside warm home. Then before moisture evaporates, 2nd battery is collected from inside and back into the sub-zero temps. I was wondering if the freezing of moisture on circuits "may have caused" the landing struggle. The 1st battery was exceptional, smooth lifts & smooth landings... performed about 8 each, all smooth. Then 2nd battery, after bringing H & RC back outside the oddity in landings.

My next flight day will be to keep H & RC outside in cold temps to see if that makes a difference.

On a separate, similar cold issue: When I performed a few quick elevation climbs using more amps. All the motor lights blinked and the rear LED flashed Yellow or Red, then returned to Purple. This occurred each time higher amps were requested (not extreme but higher amps)

Shortly there after, I received a popup indicating something to the effect: Cold Temps, Battery warning, and maintain lower attitude. This is when the RC is still showing mid-15 volts for H.

The manual indicates a multicolor LED flash as low voltage warning codes for H.
I assume that is sensitive due to extreme cold? Since I haven't flown the H above freezing, assume it wouldn't be so temperamental to amp usage.

I may need to turn on a notice, I eventually received a popup to land immediately, battery voltage low warning. But I didn't feel vibration or hear any tone warning.

 

[Steve Carr]

This occurred each time higher amps were requested (not extreme but higher amps)

If you perform your climb when the battery is still warm, it will generate more heat and tend to keep the batt warm longer. Later in the flight the batt will be cooler and the voltage will drop quickly during a climb. You will notice the batt voltage rebounding while in descent. I've noticed the voltage varies much more during extreme cold compared to warm days. There is also a heater inside the H to warm the board. I presume that will add a load to the batt as well.

When I'm flying in very cold weather, I keep the minivan running. If I need to warm up between bat changes I put the H, ST16 and my fingers inside the car to regain a bit of heat. The humidity inside the car is going to be low and condensation has not been a problem compared to going inside a building with higher humidity.

 

[NorWiscPilot]

Doug,

First things first - am I reading correctly about your compass calibration exceeding the 60 second limit? What 60 second limit? It's 30 seconds.

Second: I fly in cold weather all winter. Will get in a few flights when the temps are below 10 degrees Fahrenheit. I have noticed a few issues with the camera (gimbal losing flexibility) as well as the ST16 tilt and speed sliders taking a little more effort to move.

Third: My first H480 exhibited a tendency to drift and wanted to tip over on landing when it encountered the drifting. Aborting and trying again typically was successful. However, I cannot say I've never tipped it again. Also, a Bind-N-Fly unit (without Real Sense) has been my favorite ever since. It has also tipped, irregardless of temp ranges.

What I usually find out is I am near power lines (buried) or forgotten to be disconnected (12 gauge extension cord to lake side dock). Aside from those environmental issues, and an occasional side hill landing attempt, the incidences of motor power down and resulting tipping are few.

I do have one question: What do you mean by "Actually I think that's pretty cool how the Yuneec system stops the props and motors continue." The motors are not turning if the props are not turning (assuming the props are attached).

If any motors are turning, it would be the fan(s) in the Real Sense module as well as the ST16.

Hope your landings smooth out!

Jeff

 

[Dougcjohn]

Jeff, thanks for info!
30 sec would be correct, I didn’t recall precise time when writing post but knew it was shorter than time I was taking and needed to shorten Cali process.

Motors turning audio... my error, meant system remained active and audibly “On”, not fully cycled down like DJI and lifting the stick up spun props back up without requiring to initiate a startup.

The ST16 Cali resolved the drift, and the landings were silk smooth on 1st battery... then struggled to land smoothly on 2nd battery after H & RC were inside for short period and didn’t fully dry from condensation. At least that’s my thought path.

I’ll need to experiment a bit more. I’m confident it wouldn’t be an issue in warmer temps and it’s related to sub-freezing temps.

Not famailure with unique behaviors of Yuneec yet, and beginning initial flights in sub-freezing temps probably isn’t the idea staring point... still entertaining & enjoyable!

 

[Indiana Larry]

I would like to share a recent cold weather incident that might have some bearing on this cold wx mystery. I have an updated fully, with real sense Typhoon H and CGO3+. During the day I performed all calibration setups successfully, did some short test flights loaded the transmitter and aircraft in the trunk. Several hours later, the local temps dropped below 25 degrees F. I fetched the H and transmitter from the vehicle trunk to test some more outside. Powered up properly, the H flashed fast yellow and the transmitter flashed temperature warning. Powered down OK, did not launch. The equipment temps had leveled down to outside cold temps.

I'm searching the blink code card for an explanation, there is none on the original code sheet. I've since learned the are some new codes i.e. the pink blinks when the H is using the Russian Glasnass satellites. Now I discover the temp warning fast yellow by accident..

Is anyone aware of Yuneec publishing an updated blink code list or has anyone out here discovered the new blink code additions that might share with us pilots???

Obviously we must launch the equipment within a temp range to be safe. For example warm the equipment inside some where before initiating a cold day launch. Apparently once the units come from a warm environ and we launch, on a cold day, the aircrafts circuitry could be safe because of internal heat generation. Thus no temp warnings.

The other side of the sword would be, if its hot outside and your equipment comes from an air conditioned environ , good idea to let your equipment level to ambient temps before initializing. Wait maybe ten - twenty minutes to stabilize.

Anyone?

 

[Dougcjohn]

Larry, thanks for the info. I did have a pop up that indicated ESC was cold and needed to warm up. Then about 15 seconds later the RC appeared to be ready.

I'd be interested in the additional flash codes too if available and the various messages that may appear on RC.