Trouble in Paradise: P6e teething problems

[0nemildot]

Hello everyone,

First off, it probably comes as no surprise that John Beech is a wonderful guy and motivated to help anyone with his product! He suggested that I post this for the benefit of others.

Here is my setup:

Pantera P6e Quattro head with 600mm FRP blades

Motor: 720kv Pmax
ESC: Promodel PDRE5120DLHV
Flight Packs: New Glacier 45c 5000mah 4s in series for 8s

My problem has been what I would consider abnormally short flights that end with the motor gradually losing power. The flights last from up to four minutes on the first flight and then 2.5-3 min on subsequent flights. I am basically only hovering at this point due to the above issues. My last flight yesterday was 2:30 with cell voltage right after at 3.86-3.87. Starting voltage was 4.15 per cell. I did not note the mah used for the flight.

I had programmed the ESC with HiFei V4.11 software - I downloaded this because I have had no success in looking at the onboard ESC log with any software that I have tried (Promodeler, Turnigy SuperBrain, and HiFei) and wanted to use the Heli Mode programming.

I used the programmer to set a low governor for 1600rpm but it sounded much faster than that and continued to gain head speed after I lifted into a hover IGE. To make matters worse, I stripped the main gear teeth on this flight. My throttle curve was set flat at 61% to acheive the calculated head speed. Both ESC, Motor were very warm after landing, i could keep my fingers on them for 5-6 seconds.

I set PMW to 12khz with auto timing, soft start, standard current limiting, LVC for 8s and soft cutoff.

The Heli mode features were set for spool up rate of 1, governor gain grade 3, HS change rate standard, ESC output L. Limit lowest, with a 15sec AR recover time.

The previous owner suggested not using this ESC, and suggested going straight to a new castle. I am not sure if that was due to preference, or difficulties experienced with this ESC. I suspect this is a good place to start. I thought that the gear lash was set correctly, over my previous 6 flights I had not seen any unusual wear on the gear. I think that the governor was not working and the high head speed was the reason for a shredded main gear.

Data from the ESC would be a boon to see what is going on. Anyone with this setup figure out how to see the flight log?


I have experience with a Blade 230s, so my understanding of what the Pantera should sound like at different HS is almost non-existent.

Any help with this would be appreciated! Thanks in advance.

[flyingquisinart]

I have zero experience with the e-Pantera, but have you tach'd the head speed? I've used a phone app that will get pretty close. Just wondering if it's faster than you think causing issues.

Just 2 cents.

[jbeech]

We need data. Head speed, as has already been suggested, is important.

We also want to know many mA are put back in the pack following flight. If it were me, as soon as you feel the power 'sag' I would immediately land, wait for the pack to cool down a little, then charge it. Here's are battery goals . . .

a) Never use more than 80% of capacity
b) Recharge to 95% of capacity
c) Store them at 50% of capacity

Thus, solving for 80% for a 5000mA pack (regardless of whether it's a 4S, 6S, 8S, or 12S) the simple math is 5000 x 0.8 = 4000mA. If your charger says you put back in more than 4000mA, then reduce the timer setting on your transmitter. If you have the transmitter set to chime at 6 minutes and you put in 3000mA, then up the timer to 7 minutes and check it again, then 8 minutes, etc. Do this and instead of pack-life measured in 10s of discharge cycles you can expect 100s of discharge cycles.

By the way, if I may birdwalk on the subject of used batteries packs, this is why I never buy used battery packs, especially from 'experts' because I see them take brand new packs to a fun fly (most especially guilty are the sponsored pilots who are using their sponsor's battery packs), hammer on them to show off their sponsor's helicopter, then on the last day offer the 'barely used' LiPo packs for 1/2 the going price, or even less. The unknowing swarm to buy them thinking they're getting a deal. Thing is, 6 months later when their pack puffs, or it has some other failure mode, they never grok what really happened. Just saying don't buy used packs no matter what.

Next, charge to 95% of capacity. This is my own personal practice because battery packs are pricey and I've discovered 95% is quicker than waiting for that last little bit when the charger is going slow (plus I just don't miss the missing 5% in practice).

Last thing about battery care, store them at 50%. Some chargers have a storage program where you just run that cycle and it'll do it for you. If your doesn't then discharge and stop the charge at 50% capacity before putting them away. Believe me, this will keep them from puffing better than anything else you do.

So there you have it, land as soon as it sags and see how many mA are being used. Tach the head to establish the baseline RPM (1600 is good for sport flying the Quattro head in my experience). As for the ESC, set the PWM to 8K (always use the lowest setting unless you just want to experiment), and once you have some data to share get back with us. As for the motor being warm, that's OK. Take its temperature if you can using one of those inexpensive infrared thermometers (the one with a laser pointer so you can see where you're measuring). Write the data down (or make a note in your phone, which is what I do), but don't rely on memory. Also take a couple of temperature measurements at the ESC while you're at it. Ditto the batteries. Heck, I'm so anal I also check at connectors because I once found a bad solder joint because a connector was hotter than the others.

By the way, you made mention of not knowing how much a P6e with Quattro head should sound. I suggest you simply watch and listen to this clip a few times. While it's a 10S pack instead of an 8S pack, the performance should be similar because we're not hammering it. Your duration may be a touch longer with an 8S set up than the 10S (yes, it's counterintuitive but there you have it).

P6 start up and flight - http://www.audacitymodels.com/Produc...2/Default.aspx

Finally, while it's early to speculate as to why you're having this experience, I would hazard a guess. In short, I like 70C packs (burst140C) despite them being pricey. Basically, I've learned LiPo batteries marked 40C (80C burst) are cheap for a reason.

[0nemildot]

Data. Indeed.

Is it me or has anyone else had difficulty pulling data from the ESC?

John, the Promodeler software allows me to set parameters, but not access this information. I did run CP210xVCPInstaller_x64.exe for Win 8.1

Is there a solution for this?

With the 720kv motor, is it safe to run the ESC at 60% or less for a governed head speed? Or, is the preferred method to set flat throttle curves and measure the unloaded head speed and adjust accordingly?

Either way, from what I understand, this may increase ESC heating and where a active free wheeling ESC may help me get to a comfortable HS.

The other option would be to fly this bird on 6s... Trying to learn and figure it all out.

[0nemildot]

John,

I did check the video and my HS was way faster than that, could that in itself killed the main gear.

Great info on the batteries as well, pretty much my strategy.. I don't think that I am reaching LVC based on cell voltage checked just after landing. Maybe ESC heating or over voltage due to running what sounds like flat out.

Guess I need to add a tach app and ir thermometer to my kit as well.

[jbeech]

Change to 8k on the PWM from 12K before you fly again!

[0nemildot]

OK everyone, I’m back with more information, as requested. A long post, so hang in there.
After replacing main gear one, I reprogrammed the ESC to turn governor mode off and change PWM to 8K and motor timing to auto. LVC set to 8 cell/24V (3.0V/cell).
Ist pack was two Pulse 4S 4500 35C packs in series, charged to 4.18V/cell. I started with a 0-30-30-30-30 throttle curve. I spooled up and hovered IGE for approx. 60 seconds, then landed because the head speed seemed low and I felt borderline out of control, as probably expected with HS measured right at 1230rpm as recorded using the HeliTach app.
Then back up after trying a 35% flat curve. Total flight time was 139 seconds with 1815mah used, for 13mah/sec. Estimated flight duration assuming 80% pack usage would be 277 seconds/ 4.5min.
ESC temp 107F and motor temp 100F. Ambient temp 90F. Canopy off.

2nd and 3rd packs were Glacier 4S 5000mah 45C rated packs is series. These are new with 4-6 cycles on them. Start voltage 4.16V/Cell.
2nd flight consisted of a couple of test hovers, IGE and OGE. I bumped throttle curve to a flat 40% for a loaded HS of 1410rpm. I charged back 2534mah to the flight pack and did not record flight time. I’m guessing very near 4min. (I’m not a great test pilot/flight engineer…. yet) I split the entire flight into two mini – flights to hover and adjust radio settings.
Checked temps: ESC now 109-112F and Motor 104-106F. Ambient temp 90F. Canopy off.
3rd flight: Ok, so things were going along fine. I bumped throttle curve higher to 45%. Because the lower head speeds really felt soft. HS was 1620 rpm. I was shooting for a 5min flight with canopy on. This time I only flew for 2:34 before I lost power and landed. This is still just hovering in and out of ground effect only.
As quickly as I could get the canopy off, I checked the cell voltages, and they were all 3.96-3.97V/cell. (measured at 2-3 minutes after flight). ESC temp was 127F, motor 109F. 3602mah used equating to 23mah/sec. Estimated flight is now down to 2.89 min.
The ESC/motor temps seem ok, exhibiting progressive warming from back to back flights. ESC temp rise likely to less cooling due to the canopy being on. The loaded HS seems to be ok, and sounded more appropriate ( the governor was obviously not working on the first few test hovers and the HS was much higher). So why the soft cutoff? Based on the battery consumption I may indeed be hitting a LVC under load. But, the voltages recover to a relatively high level immediately following flight. Is it safe to lower the LVC lower than 3.0V/cell?
I am a bit discouraged. The flight times I’m getting just hovering seem very short to me – based on John’s guestimates and the reports from the previous operator. The ESC/Motor is not over temp. The limited flight data I’ve collected seems to indicate that a lower HS is more efficient, but will require revisiting gain settings in the iKON to establish a better feel. The recommendations for HS with the current setup for sport/scale flying have been 1500-1600 RPM, so I’m right there.
I would be fine with sport flying flight times of 5-6min and pushing scale flight to 6-7min. Is this expectation unrealistic? More concerning is that there is a power cut off issue and am not comfortable attempting forward flight and having this happen in the course of a 2.5min flight.
Is there any reason to suspect the ESC with the information I’ve gathered? Is dropping the LVC lower to eliminate soft cutoff advisable without harming my flight packs, but extending the flight times to 80% pack capacity. Would an ESC with AFW help this situation? Again previous owner did make the suggestion to use another ESC… maybe this is why.
I think mechanical setup is ok as far as the drivetrain running smooth, perhaps there is something to optimize there? Since I did shred a main gear, maybe I have something off there that is sub-optimal.
Suggestions and help appreciated!
Chris

[0nemildot]

I cut pasted from Word, sorry the format for the above post is so compressed.

[jbeech]

Why are you running 40% curve? Put that bad boy up to about 85%. You should see a head speed of maybe 1850RPM, give or take. Dial in the cyclic to throttle of maybe 15% (so when you put in cyclic, e.g. aileron or elevator, it gooses the throttle a little bit for you). Anyway, running that combo so low is waaaay outside the parameters of the ESC so try this and report back.

[helihammer]

My data may not be the best comparison to yours as I fly with a Castle Edge 120 HV, but I'm able to get just under 8 minutes of flight time at 1600 RPM using the same Glacier batteries you mentioned. This will use right around 4000 mAH. I also have a 630 kV PMax motor, however. I just checked the data log, and to spin the head at 1600 RPM with zero pitch takes about 37 amps and 1200 watts. To hover at that speed takes about 52 amps and 1680 watts. My ESC reached a maximum temperature of around 150 degrees F after flying today (90 degrees F outside).

I have the throttle on a 3 position switch, with the throttle curves being something like 40, 70, and 100% flat. This way, I can spool up the stage II clutch nice and easy, and then lock into 1600 RPM after spool up. I used to fly an OS 50 with a governor, and this gives the best approximation to what I'm used to.

I don't think it's unreasonable for you to expect a 5 to 6 minute flight time, especially since I routinely fly for 7 if I'm just tooling around.

[helihammer]

Scratch that data I mentioned. After reviewing it, I thought it seemed high, so I repeated the test flight which consisted of spinning the head at 1500, 1600, and 1700 RPM with zero pitch, and then hovering at each of those speeds (with a sample rate of 5 Hz)

Here's what I found:
Idle (head rotating at zero pitch):

1500 RPM
18.2 A, 573 W

1600 RPM
20.8 A, 654 W

1700 RPM
23.3 A, 735 W

Hover

1500 RPM
30.3 A, 954 W

1600 RPM
33.7 A,1061 W

1700 RPM
34.1 A, 1069 W

This is with two Glacier 4S 5000 mAH 45C packs wired in series. I usually set the timer at 7 minutes for sport flying.

[0nemildot]

John & K3BTUO,

Thank you for the information. Finally, success!

John, your suggestion to up the throttle curve solved the soft cut offs I was experiencing... I presume the ESC was hitting a thermal protection limit.

Using both the Pulse and Glacier packs are yielding a flight time of 4 minutes with the TC at 85% flat.

K3BTUO, are you flying with a Quattro head? I'm just curious why your flight times are longer. Maybe the lower kv motor is more efficient? Based on your data, there really didn't seem to be much difference in amp draw between your middle and high head speed.

In an effort to explore longer flight times, I did play with 6s batteries. 2 3700mah packs in parallel yielded 6:23 flight - could go to 7:00 based on John's formula.

Just to say I did it, I tried 4s. It hovers, and I'm glad I was able to land it.. I'd have to make to many setup changes to make it work.

The Quattro develops so much thrust, I want to try and optimize my settings for longer flight time. Perhaps a ESC with the ability to safely run lower throttle settings will help me get where I want to go. Maybe I'll just fly with 4s 10000mah? Something to explore, but definitely going down the road of diminished returns.

The 6s is ok for hover practice, general forward flight. The 8s setup is fun for fast sport flying and big air stuff. I am just glad I'm too the point of being able to get out and fly her!! Having a blast!

Next project is to get the blade phasing perfect.

Thanks for the help,

Chris

[jbeech]

Play around with upping throttle from 85% to 90 and 100% and report back.

[helihammer]

Nope, just the standard twin blade head here. The lower kV motor spins slower with the same voltage as we all know, but I wouldn't think it's any more efficient. It's billed as being about 85% efficient. I'm pretty sure the all-up weight is about 8 pounds. I'd be happy to share some more data with you if you need it.

[Medic33]

You thought your post was long? This one's turned into a monster!!!
First some data... then some thoughts (more data than thoughts, though...)

I keep full logs on my Pantera using an iOS app called RCLogbook, so I can tell you about each of her 102 flights....

First of all, the machine:

P6e
Skookum 540 / Align DS510 servos @ 7.0v
12S / 3300mah (2x 6S 3300mAh pack sets, 1 Hyperion G3, 1 Thunder Power)
Scorpion 4025 400Kv (I think? Might be 420) / CC Phoenix HV 80
Stage II (clutched) conversion
Edge FB CF 610mm main blades (RNFBL conversion)
AUW 8.0lbs (approx)

So, over 102 flights, I'm getting average flights of about 10:30, with amp draws around 22A, to a discharge of 3.8v (about 60% of the battery). Longest flight was 15+ minutes, but that went slightly below 20%. It's completely John's fault, because he designed the helicopter, and I was having way too much fun. Flight style is sport scale, 3D is not my thing.

So, Power consumption equivalents for you:
22A/H = 366mAh/min = 6.1mAh/s (so I'm burning half the power you are, on a 12S vs 8S system)

My Watts are roughly 1000W - on a two blade head.

I would look at:

1) Your batteries. They are done. I am in total agreement with John and others about used batteries. Just don't. They are also on the lower end of the battery spectrum. Batteries, I've discovered, are one of those you get what you pay for things. Cheap batteries just can't sustain the amp load. Your power let off at the end, does not sound at all like ESC down throttling because of heat. It totally sounds like batteries fading under sustained load.

2) ESC / Motor / Headspeed.

First of all - is the ProModeler ESC actually a HiFei unit? Is the firmware you are using compatible with the hardware in the ESC? If there's any doubt - get the correct (and that means the firmware supplied ONLY by John) firmware on there. Failure to do so will result in a crashed helicopter, and destroyed motor and ESC.

I don't think the ProModeler ESC is an active freewheel unit (correct me if wrong). If it isn't, ESC and motor kV need to be matched to get your desired headspeed at around 85-95% throttle range. Lower than that, and you are ineffcient (turning electrons into heat, not power), higher than that leaves the governor no compensation room.

There is no exact rule on what the headspeed decrease should be from 2 blade to multi blade, but you definitely need to be running slower. I run a very happy and stable 1650 on 2 blade.

In the day and age of the FBL controller, high HS are not required - even for 3D. Jan Henseleit (hmmm...) did a very nice scientific study on roll/pitch rates versus headspeed versus watts a couple of years ago that killed the high headspeed thing. You are just burning up electrons uselessly.

Let's say with your 4 blade head (so double the area, not quite double the lift, more than double the parasitic drag), you want to step it down to 1400:

We'll use 3.8v per cell as a good half way point. I will use the term N1 for motor speed, and NR for rotor speed below.

(8S x 3.8v) x (motor kV) x 0.9 (efficiency correction) = N1 @ 100% throttle
30.4v x 72kV x 0.9 = 19699 rpm (N1 @ 100%)
N1 / (8.7:1 gear ratio) = NR @ 100% (theoretical, you will never get this in RL - drag)
19699 / 8.7 = 2264rpm (NR@ 100%)

To achieve 1600 rpm NR, you would need to run your Throttle Gov at 70% - too low.
To achieve 1400 rpm NR, you would need to run you Throttle Gov at 62% - way too low.

(To determine approximate % for a given headspeed, first calculate the constant:
100 / N1@100% = 100 / 19699 = 0.000507
Then take your desired NR and multiply it by the gear ratio to get desired N1:
1400 x 8.7 = 12180 N1
Then multiply desired N1 by the constant to get the approx throttle gov %
12180 x 0.00507 = 61.75)

Whew... Long story short - your motor is the wrong kV for your desired headspeed. You are running very, very inefficiently on packs that don't appear to be capable of it. Now you have the math, you can look around at the avaliable motor choices, and choose one based on battery voltage, watts required and headspeed desired.

BTW - a good estimate is 100W / lb for a 2 blade machine. Each extra blade adds about 50% of the base requirement to the mix. So 100W/lb for 2 blade would be 200W (100 + 50 +50) for the 4 blades.

BTW (again): Scale ships fly around 50-100W/lb, 3D ships can be 300-350 W/lb PEAK. If you are not flying 3D, you should be more focused on the continuous watts, not the peak, momentary max (which is what manufacturers advertise).

Ok. Now I'm really done. This time I mean it.

Ok, I lied. Higher voltage systems will ALWAYS result in lower amperage draws for the same Wattage output. My 22A/h on 12S is (roughly) akin to 44A/h on 6S. But, as I think I've shown above, you need to tailor the WHOLE package together to work efficiently. And I'm a Scot. We're all about the efficiency. Steam Engine - more efficient than horse. Bridge - more efficient than swimming.

Totally done now. Honest.

[jbeech]

Beautifully thought through and presented. Attaboy!

[Medic33]

Just sharing the wealth with my brothers & sisters in Pantaradise!!

Caveat: I didn't figure all that stuff out. Sat at the feet of the masters (John, Jan, Peter Wales, Curtis). I just took notes!

[0nemildot]

Medic33,
Thanks so much for your robust reply. The information that you painstakingly provided helped me to “connect the dots”. I apologize for not acknowledging your contribution sooner, but as we know, life steals hobby time.
As John always implores, I am reporting back!
Since I’ve been simultaneously climbing the learning curves of both heli power systems and FBL controller setup, I have been busy. I have revisited flying using just a 4S/
5000mah battery. Adjusting the iKON and adding larger tail blades has made the heli comfortable to fly, with solid tail response.
On the above battery running a flat TC of 100% I am arriving at 1100 RPM with 7min flights. This correlates to 8.7-8.9 maH/second consumption. This HS allows fast forward flight. Since I am still new to helis, being able to stretch the flight time with sedate HS fits my current abilities. The normal HS is great FUN, but is wasted on my current skill set.
I painted myself into a corner assuming that I needed to fly this setup on 8s without understanding the relationships between motor kV and input voltages. Especially with the 4 bladed head. My approach of manipulating voltage allows me to work with what I have on hand – certainly not optimal, but will meet my needs now. I think 6S on this setup is promising, hitting the sweet spot of ESC efficiency with desired head speeds. I still think a different ESC that permits safe lower throttle percentages will work even better.
Anyway, I am learning and having a blast. Again thanks to all who have made this a bit easier by sharing their hard won knowledge.
Keep the rotors turning!
Chris

[jbeech]

Wonderful having you report back. I think folks will be amazed at what you are saying about the set up and flight with a single 4S-5000 pack. Any video yet? Are you flying solo, or at a club? Any other helis, or are you going it alone on that front? Any comments from others about the model? And finally, for the main questions . . . are you glad you bought it and are you having fun?

[0nemildot]

Hi John,

I am pretty much a solo flyer. I do have a friend that flies (planes) and we get together, but right now I am lone wolf on the heli.

I endure a long commute for work and have no interest in adding to my miles driven for this hobby. Also, if flying clubs are anything like shooting clubs, there is probably less flying being done vs standing around and talking. Then there are yearly dues, AMA membership, and the list of rules/schedules that must be followed. I probably sound anti-social and unconcerned with safe flying. That isn't it, I can just fly more instead of commuting to a field. If you know of a solid club with good people, I may be convinced. There is a heli only club in Orlando, but I like my planks too - and would love a place that I could do both.

I started flying heli in April with a 230s as mentioned previously. I purchased the Pantera and haven't looked back. I like flying it more than any other airframe I own. This is the nicest ship in my fleet.

Other than friends and family that are wowed by the spectacle of a big electric heli that spools up like a full scale, I don't have any opinions from other heli pilots.

I am having a blast with this thing! I really can't wait to explore my low head speed setup.




I will work on video, and a proper thread devoted to the setup.