9 Month Nova-Quad and Pilot Summary

It's been an interesting ride so far.

I had been out of RC-hobby for so long, things had changed (electrics weren't really popular back then) . I didn't even own a 2.4ghz radio-set. My piloting skills were pretty rusty and I had never flown a hobby-class helicopter before.

Between starting with smaller WLT-v262 (as a quad outdoor flight trainer) and then buying the pre-built Nova, I think it worked out rather well. But even after buying the Quanum Nova PnF model, there was a bit of a learning curve ... getting up to speed with:

• Electric quadcopter hardware (ESCs, Flight-Controllers, etc.)
• APM hardware in general (Arduino-based FC, GPS, compass, etc.)
• Advanced APM hardware tech like Telemetry
• MissionPlanner and DroidPlanner software
• Quadcopter cameras and gimbals
• FrSky Taranis and OpenTX
• Helicopter piloting skills (so you don't crash :)

By having it pre-built, it allowed me to focus my attention on other facets of the hobby while starting-out. There is also a Nova/ CX20 model that comes with a (very) entry level radio pre-installed.

While the stock uBlox GPS-Module works acceptably in clear-sky weather ... in over-cast clouds or back-yards (close trees blocking quad's view-angle to satellites) ... it doesn't work so good. It ends-up providing low satellite detection and a high HDOP (poor GPS signal quality). Aware of it now and not much of a problem since I only fly in "nicer weather (party-cloudy or better) and I also use DroidPlanner (on my Android tablet) to monitor GPS-signal in real-time.

The out-of-control crash-landing into the neighbor's tree last October was a major set-back. Final cause of crash was determined to be ... "attempted RTC (Return-To-China) fly-away" due to flakey GPS (RTL/ Fail-Safe failure). I've had my share of hardware problems involving GPS (turned-out to be bad/flakey cables). Also, with vibrations causing Wobble-Of-Death (WoD). All that is corrected now, and the Nova has proven to be a dependable aircraft in recent flights over the last months.

The new camera gimbal upgrade is great. So great in fact that I know that I always want at least one multi-rotor aircraft running a good camera on a gimbal. The problem is that the gimbal's extra 185-grams seems to have put the Nova close to it's payload weight limit. It is no longer a nimble quad that can be flown close to ground and obstacles. It's more like an aircraft that you carefully fly up to a safe altitude and use for Aerial Photography (AP). In it's new weight class, the quad seems to be under-powered. This also causes it to be more susceptible to the forces of high winds.

To be perfectly honest, I think some of the problem might also be my (slowly advancing) helicopter piloting skills. I simply don't get that much "stick-time" to practice (I need to resolve that if I want to progress). Currently, I still rely on a powerful and nimble aircraft to get me out of hairy situations. I still have a fairly constant fear of crashing and of a fly-away (due to GPS failure). The extra weight has definitely made it less responsive. Hopefully, I can tune some of that away.

Anyway, I still love this hobby. For me, it's always been about the hardware building, electronics integration, programming config, and the piloting challenge of RC-Aircraft (now robotic ones).

It is possible to stay safe and push-your-limits at the same time. I think that is part of the fun and excitement of the hobby.

The Quanum Nova (Cheerson CX-20 clone) has proven to be a good aircraft and valuable introduction into the world of RC multi-rotors and ArduCopter for me. Sure, it's only a little 350-class quad and it's (nice looking) plastic body is kind-of fragile (if you crash-land), but I still like having it in my "hanger". It is GPS capable and it's been a good model in my progression through the hobby.

Test Flight eval and Maintenance

Adjusted Extended Parameter (main PIDs) to be the same as I was running last on v3.1.2 (just some small edits ... nothing major). Set THR_MID to 650.

Gimbal is working pretty good. However, I think it needs some tweaking to get rid of occasional "motor buzzing" and also to remove a bit more jello. It was pretty windy (and quad was getting tossed around quite a bit) so that might have been the cause.

Removed black foam padding from bottom of battery-bay so my batteries will fit and pull-out easier. With the added power draw of gimbal ... seems my Turnigy 2700/25c puffed-up a bit and got hotter than ever (but they were already a tight fit).

Retrieved logs. Vibrations are only fair. Balanced props on my trusty DuBro Balancer. They have gotten scratched up in the last month or so, but still needed little to no balancing.

Flight Test with May 2015 Mods

Well, it stopped raining here in Texas long enough to do a flight test of the following Mods

• Upgrade to ArduCopter v3.1.5 (custom Cheerson Uart) and default params.
• Eachine SimpleBGC Lite Metal Gimbal install (carrying Mobius)
• FrSky Sbus to CPPM Adapter
• New Taranis programming (Flight Modes and Logical Switches)
• APM_252 FC-case Barometer Mod. 

Flying conditions and site were not ideal. Winds were 12mph with gusts and I was in the back-yard where there is no space (unless you like trees and buildings).

 

It needed an AutoTrim before it would do a decent hover, and THR_MID looks to be around 650 (635 wasn't enough).

 

Vinnie's custom AC3.1.5 seems to be working fine.

 

The gimbaled and stabilized Mobius video looks great, but man ... what a trade-off. Does "flying turkey" ring a bell? Not sure I like it.

 

Also, for the first time, it puffed my 25c battery a bit, and it was real hot.

Off to tune some PIDs and balance my props.

Landing Gear Mods

Need some extra height for gimbal. I'll try to put evolving LG mods all on this post.

Tried this mod first. Lowest part of gimbal to desk is 3/4 inches. Had to remove because it makes landings too difficult on hard surfaces. On the slightest rough landing, these act like springs, and bounce the quad back into air. It then flips over and crashes upside down. Removed after a couple of batteries thru.

Try two. The lite-foam pipe-insulation seems like a good material to get some height. Lowest part of gimbal to desk is now 7/8 inches (so a little better). I would prefer it to be stiffer, but it's not too bad. Notice it's 2 layers thick (but only on bottom for max. height). Inside layer is not complete tube/circle and is tie strapped to LG first (to prevent slippage). Black rubber bumpers are not needed and saves 13 grams. Will try it for a few flights.

Only cons are ... it will bounce/flip on hard landing and ... foam surface catches wind (rocks gear?).

 

 

EDIT 2015-07

 

Well, I think I found the best way to mod the stock white plastic landing gear for use with 2D gimbal. These will raise the lowest point of the gimbal to 7/8 inches or 23 mm ... as high (or better) as foam, but without the surface area (acts as sail in wind) and springy-ness.

 

HK now has Extended Rubber Feet for Landing Gear Skids -

Fits Quanum Nova and Cheerson CX-20.

 

 

 

 

 

 

FrSky Taranis - 6+2 Flight Modes and Logical Switches Setup

With DroidPlanner running on tablet (touch-screen access to all Flight-Modes), it hasn't been a big priority for me, but I finally got around to setting up all my Flight-Modes and Logical Switches on the Taranis (using OpenTX Companion).

They are now on 3+2 switches.


My Flight Modes for AC 3.1.5:
1. Stabilize   (SD-down)
2. Loiter       (SD-up)
3. Alt-Hold  (SD-mid) (SG-up)
4. Drift         (SD-mid) (SG-mid)
5. Land        (SD-mid) (SG-down)
6. Auto        (SC-mid)

... and in Extended Tuning:
CH7 = Simple-Mode & Super-Simple w/ GPS (mode modifiers)
CH8 = RTL
(both of which have own dedicated Taranis switches ... SE & SF)

So, how did I come up with this? Well, my main-mode switch does my 3 favorite Flight Modes. Up (to sky and GPS sats) and Down (to ground and me) are the easiest to find (without looking). If left in the middle (it holds a hover and it's altitude ... I use this a lot). Also, now with the secondary-mode switch, it can be changed to 2 other more rarely used modes. RTL is on it's own switch (easy to find for emergencies), and so are the 2 Simple-Modes. Finally, a separate switch for Auto-Missions.

It helps to write down "the logic" of what you want before starting. This is how I did it (with some help from ScottFlys as I was learning).

EDIT May 2019:

The Logical Switch programming and Special Functions have been enhanced for this model (now named Nova-360). It now has enhanced sound features.

Upgrading firmware to 3.1.5 (Cheerson custom Uart version)

I'm finally upgrading to ArduCopter v3.1.5. VinnieRC took the time to re-compile a custom Cheerson Uart version of v3.1.5. Now, Telemetry/Uart port works on this Cheerson APM_252_v2.0 Flight-Controller. I installed it from MissionPlanner v1.3.27. .

I like v3.1.5 because:
- The major v3.1.2 "randomly kill throttle in flight" bug is fixed (yes, I've experienced it)
- Terminal feature (for Diags, Troubleshooting, and Settings) is still in Code and works.
- The code is simpler than v3.2.x, and I think it runs better on the limited processor power of a little APM-based unit, without getting dangerous cpu "LongLoops" cycles. Reportedly, v3.2.x can over-burdened the limited APM with "staying stable in wind" calculations and altitude-control suffers. You can even keep your (processor intensive) detailed Logs recording enabled. I'm willing to give up v3.2's Position-Hold flight-mode, Spline-WayPoints, (and a few other little features) ... for a more stable, dependable, and easier to troubleshoot aircraft (at least for now).


I Reset Parameters to Default. I will add my custom parameters from a pre-written list, manually later.

These are some AC3.1.5-Defaults. However, some are different than v3.1.2-Defaults, so I thought I would list them here (since they are important to be set like this). I am using 915mhz radios, but no PowerModule yet.

AHRS_GPS_DELAY,2
AHRS_GPS_GAIN,1
AHRS_GPS_MINSATS,6
AHRS_GPS_USE,1
AHRS_ORIENTATION,0
ARMING_CHECK,1
COMPASS_EXTERNAL,0
COMPASS_ORIENT,0
COMPASS_USE,1
FENCE_ENABLE,0
FRAME,1
FS_GCS_ENABLE,0
FS_GPS_ENABLE,1
FS_THR_VALUE,975
GPS_HDOP_GOOD,200
PILOT_VELZ_MAX,250
THR_MAX,1000

I purposely reset my parameters to get a fresh copy of v3.1.5 defaults (and to not carry-over any depreciated params). The params and settings listed below will not really include any that are already correct as Default. I also don't plan to give explanations for each, so you can just search my blog for notes and definition of each.

I then did a complete calibration of all Mandatory Hardware (radio first). Compass calibration seems a bit different this time.

Set my Flight Modes:
1. Stabilize
2. Loiter
3. Alt-Hold
4. Drift
5. Land
6. Auto
... and in Extended Tuning, CH7=SuperSimple and CH8=RTL
(which I have on dedicated Taranis buttons)

Changed these non-Default parameters:

FLTMODE1,0
FLTMODE2,5
FLTMODE3,2
FLTMODE4,11
FLTMODE5,9
FLTMODE6,3
CH7_OPT,13
CH8_OPT,4

ANGLE_MAX,3000
FS_BATT_VOLTAGE,6
FS_THR_ENABLE,1
LAND_SPEED,30
LOG_BITMASK,958
MOT_SPIN_ARMED,0
RTL_ALT,2000
THR_MID,660
WP_YAW_BEHAVIOR,1

My starting PIDs, but also AC 3.1.5 Defaults

I guess it's ready for a test flight, THR_MID determination setting, Auto-Trim, etc.

I used the above params for the first test flight.

Parameter History:

After first test flight with above Default v3.1.5 params, I changed them to this. This few edits makes them the same as my last (working fine) v3.1.2 params.

Flight Session #21 used these. THR_MID,660. These don't work so good any more, so it must be the extra weight of the gimbal that is installed now.

Current Parameters:

On Flight Session #23 changed to these (below) Nova params that I got from Skywarka. They are the best yet and flew the Nova nicely (with gimbal). Also, the Mobius audio for the motors sounds better and more even. Logs and logging are still working fine. Final THR_MID for this weight is 670.

 



 

This is my Nova's current param changes list (over-rides any values above) as of July 11, 2015

COMPASS_EXTERNAL,1  (yes, external compass - my mod only)

COMPASS_ORIENT,2        (yaw compass 90 degrees - my mod only)

GPS_HDOP_GOOD,220     (extra buffer that effects final GPS accuracy very little)

RTL_ALT,4000         (don't want to RTL into the side of a tall structure on hilly terrain)

THR_MID,670                     (for All-Up-Weight of 1153 grams)

WPNAV_LOIT_SPEED,800

WPNAV_SPEED,700

 





Compass Calibration procedure

Did I miss a memo? It seems the Compass Calibration procedure has changed?

Edit 12-2016 : Many in the forum pilots say "Dennis Balwin's Way" is the best way to calibrate compass. Also, if having trouble over 915Mhz SiK Radios, try a good USB cable. OK ... now back to the old post.

Now, it's just ... "One strategy for capturing all the white dots is to rotate the vehicle slowly so that each side (front, back, left, right, top and bottom) points down toward the ground for a few seconds."

It's more like the linked video. There is certainly no "dancing" or "chair spinning"in that video.

All I know is that I'm trying to calibrate the compass via 915mhz radios. After trying "compass dance" and "spinning chair method" ... MP errors out before it Auto-Completes. Many white dots are still left.

Best I can tell, after some testing (and multiple tries for a clean compass calibration) the new procedure is very easy.

Initial Setup/ Mandatory Hardware/ Compass/ Live Calibration (at bottom)

Holding the quad in front of you (like it's hovering) ... you slowly rotate it these 3 ways (toward ground), until it's back where it started from.

1. Pitch forward 360 degrees (toward ground). Two complete times (2 revolutions)
2. Roll it 360 degrees (toward ground). Two complete times (2 revolutions)
3. Yaw it 360 degrees (on it's side, like a wheel rolling on the ground). Start with motor(s) pointing directly to ground and Yaw it all the way around. Two complete times (2 revolutions)

Toward the end of step 3, it should beep (auto complete) and give you the Offsets. If it won't complete:

1. Just try again. If done clean--and-fast it seems normal for it to Auto-Complete early, toward end of step 2. If it misses a dot early, it's easier to just reset.
2. Be sure radios aren't too close (resend errors cause dots to not populate properly?).
3. Go slower and turn more perpendicular and carefully. Slightly sway as each major "face" points straight down to earth.
4. Start over and add step 4 below ...

4. Hold it like a cross (instead of X) and pitch-rotate so each motor points to ground. Turn it 90-degrees and do the other 2 motors. Some time during this Step-4, it should Auto-Complete.

It's something real close to this I think. I used the above, got a nice (clean and fast) calibration done (over 915mhz radios with ECC on) and haven't repeated it since. It's been working fine in flight.

Notes:

• It's normal for it to show 2 compasses. It's normal for phantom/un-used Compass-2 to show Error:99.
• This is with AC 3.1.5 and MissionPlanner 1.3.27.
• I think it's better to go outside to do compass calibration. This removes any chance of structure interference during calibration or general compass operation (finding exact North, etc.).
• I leave Auto-Dec on and go outside to calibrate compass. This allows a basic GPS fix and then FC can use Auto-Dec (lookup-table based on GPS). I'm not sure if Declination is used during calibration or not, but maybe it is.
• If inside with no GPS, I temporarily turn-off Auto-Dec and set it manually during compass calibration. However, other benefits of going outside are undeniable.
• My original Compass Calibration notes are in a section here (most still apply). The last time I previously tried to calibrate my compass (months ago) the normal "compass dance" worked fine for me. But not now.
• If compass is set to External, it uses the compass's orientation parameter (COMPASS_ORIENT,0). If set to Internal (COMPASS_EXTERNAL,0) it's ignored (and instead uses the FC's orientation). Pretty sure that is the only difference between them.
• After compass calibration, MP should give you a pretty good indication if your compass is working. Watch heading as you yaw and pitch quad on table. While testing (only), don't power-up with Nova pointing direct North (the FC's default when no compass is attached).
• You only need one good/clean compass calibration done on quad. You don't need to keep re-calibrating it every time you fly or even at a new field or even country. The only time you need to recal is if you re-mount compass due to frame upgrade, crash, or something like that (and then you are back on the work-bench running MissionPlanner anyway). Once the compass is calibrated, you are done. Everyone should leave Auto-Declination Enabled. When you go to any field, you will have a minimal (4-6 satellite) GPS 3D-fix anyway. The flight controller uses this to look-up actual Declination on stored table.
• After compass calibration, you can check quad against a good quality conventional (old-school magnetic) compass. Test in all 4 directions and at various quad pitches. Do not use cell-phone compass. Do not get cell-phone (or similar device) near compass, especially not while calibrating or checking.