Hi Mark,
Welcome to our build thread! It’s a bit slow right now due to the weather this time of year and COVID-19. My Freeman sits in quarantine waiting for some love! 
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Hi,
I have a Freeman 2300-kit (the one without all the electronics).
I have all the electronics (Pixhawk 2.1, Mauch, …) and the load will be a Sony A6000.
But I do not have the motors.
I have only seen Sunnysky X3520 520KV with APC 15x10" for the front.
And Sunnysky 4112 450KV with 17x5.5" CF for the rear.
I cant find specs on these motors using the mentioned propellers.
The reason is that I am trying to use other motors instead (KDE Direct or Tiger Motors).
But I need more specs to find replacement-motors.
Do all the four motors have the same load in hover?
/MickeM
MikeM, Do you know about e-calc? It is a free motor / prop calclator web app, and you can select almost any type of motor, battery, prop, etc. For comparisons. I will look at the data for those motors and props, but suggest you could use the app to select a very similar motor.
Edit: I have the pro version. It has the full database. The free version is limited to the most popular motors. To me its well worth the cost. Also, I picked a 3S lipo and 150 ESC. I am sure the lipo was too small. If you tell me a cell count and ESC I will post the performance specs for those, and for any other motor and prop too.
They all have the same load if the plane is balanced properly, but they can have slightly different output settings, front to back, based upon prop size and motor Kv. Remember that forward flight is where you want to be efficient and that hovering is only a momentary portion of the flight.
See post #125 above for motor hover graphs.
Cheers!
Well, after a long delay I finally finished my Freeman rebuild. I have done several short test flights. I am pleased to report no crashes… I’d like to move forward with a Qautotune but I have a few concerns. The first one is stability. The plane flies ok in QStablize, QHover and Q loiter. So I started a QTUNE on the pitch axis. The first move was a significant yaw to the left, which surprised me. I let the tune continue for a few more minutes and didn’t like the way the airplane was responding so I abandoned the the tune and landed uneventfully. The parameters are set to comply with the tuning guide or as recommended in the QAUTOTUNE - VTOL autotune for quadplanes.
The second concern is amperage draw during the tune. In a hover with gently maneuvering, amperage is about 50 amps. During the tune you can see spikes to 150 amps. I am using a 200 AMP Mauch Power module and 60 amp ESCs so theoretically it should be fine. But the battery, XT90 connector and 10GA wire getting are warmer than I’d like. It’s not hot to the touch but definitely north of warm. To mitigate high amperage I am thinking about setting the current limit to 100 - 125 amps. What are the implications of setting a current limit.
Below, please find a link to the log from the tuning flight. You’ll see three flights; two quick test flights and an attempt at a tune.
Love to here if others did a QTUNE and the results.
Thanks,
Dave
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Hi David,
Congratulations on your re-build and successful hovers!
Your hover flights appear to range from about 2 minutes to almost 4 minutes for the QAUTOTUNE. These are significantly long hovers and would not be part of a normal flight so this is likely why your XT90 connector and wires get warm.
I don’t have any experience with QAUTOTUNE. I also don’t have any experience with the Q_M_BAT_CURR_MAX parameter but the THR_MAX parameter can be reduced from 100 to say 75 if you experience excessive throttle bursts during transition.
The Mauch PMs use hall-effect sensors so your current is not limited to the 200 amp rating. The sensor will simply clip the reading above 200 amps.
Can you describe what “ok” means? Are you not happy with some part of the performance?
Cheers!
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Greg,
Thanks for the reply. Yes, I understand the intent is to only be in copter for a limited time for landing and takeoff. Long term, I am not worried about the max current, it will be considerably less in plane.
My concern is during the tune. Each axis takes about 3-5 mins with spikes up to 150 amps. Limiting thrust and perhaps current to some value, may undermine the goal of the tune. The plan is to tune one axis at a time, land, let things cool down for 10-15 mins and move to the next axis.
I don’t have any experience with quads this big, so don’t really know how they are supposed to fly, which is one of the reasons I am interested in the tune. My quad experience is limited to DJI Phantoms and Inspire.They fly remarkable well. I don’t expect a 2m 8kg VTOL to fly similarly, but really have nothing to compare it to.
I know it may seem like I am stubbornly pursuing an AUTOTUNE. I believe it will lead to a much more stable copter, which is my goal.
Thanks,
Dave
Dave,
I still remember my first wind lesson in flying a VTOL. It was with a BEV FireFLY6. I had many years experience flying planes and then copters but never in hovering a plane in wind. It was a scary learning curve in just how much the wind and orientation can lift the tail or wings. No amount of tuning will overcome a hovering situation when the wind hits your plane at the wrong angle. Fortunately, a QuadPlane will outperform a tri-copter in this respect.
First, try to do your testing on a very calm day. You seem to be doing all the right things but be aware that flying a Phantom and Inspire will skew your expectations!
Perhaps you can ask your question right on the QAUTOTUNE blog. If I recall, the original testing was done by ARACE on a similar setup using a Crosswind VTOL.
Good luck!
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Im curious to know what power draw others are getting with their 2300 versions? I just want to know if its worth fiddling with motor angles, CG, etc.
My flight this AM was pretty poor with an average of 22A on the cruise with maximum payload. Takeoff pulled about 80A. Conditions were pretty much perfect with no wind and 18°C.
Luke,
Here is David’s 2300 current draw while hovering; about 50amps. He uses a 6s 17AH LiPo pack and a calibrated Mauch PM. I assume that he had no payload since it was a test flight.
By “pretty poor” did you mean excessive current draw? Also, for “maximum payload” did you mean 0.9kg or an all-up weight of 8kg?
Hey Greg.
I am using a homemade Li-Ion 31.5A pack. I loaded up the airframe to 8kg with a “dummy” payload.
80A draw at maximum MTOM is not too unexpected for VTOL modes. I am not worried about that. Its the current draw of 22A (give or take) on the Auto cruise that bothers me. I reduced the airspeed as much as I could but adjusting the range from 17-21m/s made no difference to the overall current draw.
Ill have another flight tomorrow morning with a CG adjusted further back and report.
Ok, thanks. Unfortunately, Dave crashed his 2300 during QAUTOTUNE and a few of us are waiting patiently for better weather (early summer) to test forward flight so we don’t have those results. Perhaps someone will post soon to help out…
What motor and prop combination are you using up front?
I’m using all stock. Those are the no name brand 500kv motors with 15x10 props.
Perhaps it is the Li_Ion pack that is making the current draw higher through lower voltage under load. It would be interesting to re-test with a LiPo pack.
Dave,
Although the main battery voltage may have been 20v at the battery, your ESC’s still may have seen fewer volts due to wire resistance. Voltage drop even on short runs 14AWG wire can be significant, so keep that in mind for the voltage that is making it to the ESC’s.
Nathan
This is interesting to me. How can voltage drop across a short, multi-strand copper wire be significant? I just measured the resistance of a 2m 14 GA wire. It was 0. So if the resistance is 0 how do you get a voltage drop? What am I missing?
I’ve been wondering about the current draw in plane. Sadly, as Greg explained, I crashed mine before testing forward flight. I was hoping to see considerably less than 22 amps. The stock 1510 is a high pitch prop, which may be causing the high current draw. The aggressive pitch is required to generate lift in VTOL but excessive in plane. I am wondering if a better engine/prop combination would lead less current draw?
Nate,
What do your believers draw while in cruise? What prop/engine combination are you using?
Im using KDE 3510XF 475KV motors with 12x12 props on my Believers. At MTOM, I get between 5-7A draw at 19m/s. Truly an excellent platform.