Sunday, October 2, 2016

QX90 Quad-Drone Enhancements

Updated October 10, 2016

I was a little hard on my initial QX90 review, REVIEW: Eachine QX90 Mini-Drone.  Before I dive into the details the QX90 will fly out of the box but it flies even better with a few enhancements.  If you fly racing quads like me you have a good understanding of electronics and how to use a soldering iron.  These improvements will be easy for you.  This post covers the parts I choose, where to purchase them, and my impressions of the flight characteristics.

After the review I began to think about what it would take to get the Eachine QX90 micro quad to fly better.  Here are some parts I purchased frm  These guys ship really fast and even put a personalized, "Thank You!", note in the box.   Who does that?  Nice touch.  The following are the parts I purchased.

CL-0820-17-11T Gear CL-0820-17-11T Dark Edition Coreless Micro Motor Set(4)8.5x20mm  $34x1 = $34

PROP-HUB3BLADE Hubsan Style Black/White 3-Blade Micro Props For The DP03 Brushless Motors (8 Props Total) $6.00 x 4 = $24

3.7v 750mAh 25C Eachine LiPo  (purchased separately from Bangood)

I wanted to get new flight camera but I noticed after I ordered the micro camera was made for 5v systems, not 4.2v-3.3v (or 1S).  The camera specs are definitely close and if I try it I will post the results.  Taking off the old motors and soldering on the new motors was a snap.  I didn't want to take the drone apart and solder the new motors to the board.  Instead, I went for the easy approach, on the stock motors I cut the leads about 1cm from the base of the motor and tinned the wires.  Next, I cut the long wires on the dark edition motors about 2cm from the base.  I wanted to give myself some extra room if I happen to cut through the leads when I trim the insulation off.  The new dark edition motors are the same size as the stock with the exception that the shafts are shorter.  Still plenty of room to the 3-bladed props on.

When I was flying stock motors I switched over to 380mAh cells.  These are the same size cells flown on the similarly sized Hubsan X4.  After you mount the new motors and props the first thing you will notice is that the aircraft is sluggish and does not perform.  The 380mAh cell does not have enough power.  I switched over to 750mAh cell.  The video Pimped QX90 is a video I made flying the dark edition motors, 750mAh cell, and 3-bladed props.

I don't recommend flying this aircraft in too much wind but it's loads of fun.  Mine still needs some tuning but it's definitely running well enough to fly and have some fun.  I don't believe this receiver has telemetry.  I can set a timer on my transmitter but I would feel better with a proper low-battery sensor.  The crash at the end of the video was due to a blade breaking off on one of my 3-bladed props which was weakened from a previous crash.

Crazy cool!  Amazing aircraft and loads of fun.

October 7, 2016, quick update.  I'm noticing the new motors get fairly hot between batteries.  I tried going back to 2-bladed props.  Seems to fly well on the 750mAh battery.  A made another video of some flights on the QX90.  Flies much better.  This aircraft is not like flying your 180mm/250mm quad racing drone but it's still great nevertheless.  Still it takes a few modifications and a far amount of tuning.  Spoiler alert, I almost got my QX90 run over by a car, lol.

October 16, 2016, I have stabilized on the stock 2-bladed props with the dark edition upgraded motors and upgraded 750mAh battery.  This provides a flight time of around 3 minutes.  There is no telemetry with this flight controller so I set a timer to count down from 2.5 minutes when the throttle is engaged.  This gives me audible warnings so I don't damage the batteries or loose the aircraft.

Photo: Betaflight 3.0.0 PIDS and gains(click to enlarge)

Following is a video I made with the new pids.  It feels very locked in to me.  Almost like flying a 250mm quad but not quite as much power. 

A big benefit of these micro-quads is that they can be flown almost anywhere.  The modified aircraft comes in just under 40g without the battery.  So although the aircraft flies fast (40-50mph) danger to people and property is very low.

Monday, September 26, 2016

REVIEW: Eachine QX90 Mini-Drone

This is my review of the Eachine QX90 micro-quadcopter.  The point that attracted me to this particular quad initially was that the receiver is directly compatible with the Frsky receivers and 5.8Ghz FPV Goggles like Fatshark.  The idea is that if you have this equipment and race drones already you can purchase one of these QX90's, bind, and your ready to fly.  I will start out by describing features I don't like or where the product falls short of my expectations and I will end on a positive note.

Box Crushed
The drone is shipped in a foam cutout the shape of the aircraft.  The block of foam is pretty tough to withstand bumps during shipment.  The plastic wrapping around the case was not durable at all and falling off by the time I received my drone.  Luckily the drone was fine and protected by the foam.  I'm not really into unboxings.  I don't care about the box something ships in so long as I receive the contents undamaged.

Poor Quality Flight Video
Like many inexpensive cameras the one on the QX90 does not handle significant changes in contrast well.  For example, fly into the sun and all the darker parts of the picture turn black.  As long as light levels within the field of view remain constant, which is almost never the case outdoors, the video is acceptable.

Motors Under-Powered
Hover is at 50% - 75% throttle depending upon how fresh the batteries are.

Batteries Too Heavy
My drone shipped with 680mah batteries which is too big for the aircraft.  The aircraft will fly with them but it's lumbering and not very agile.

Difficult to Tune
I have some difficulty tuning at first.

Now let's switch over the postive.  There's a lot of great things to like about this aircraft.  These are the product features I like the best.

$60 price point
Need I say more?  $60 is a very low price point.  The fact is you can pay more for a single component on a 250mm class racing drone than this entire drone.  If your on a budget, this aircraft is a serious consideration.  However, if your on a budget why would you have an Frsky transmitter and 5.8Ghz goggles?  I like the price point but it's a marketing play to experienced pilots with a fatter checkbook.  While I appreciate the low price point I will gladly pay double or triple the price for a high quality 90mm drone that fulfills all my exceptions.  May I'm too picky.

SP Racing F3 EVO (Brushed) FC
I really like that you get an F3 you can flash with Cleanflight.  In fact, you can also flash this flight controller with Betaflight as well with good results.  Using familiar components and software is helpful for tuning.  Although I noticed that Betaflight was really difficult to tune.  To get the aircraft stable requires far higher Integral and Derivative settings than I usually see on any my 250 quads.  I'm not sure if this is extra error is introduced by the motors, poor quality board, or perhaps it's an artifact of a short 90mm frame size.

Frsky Receiver
Super cool.  The Frsky compatible receiver is also an SBUS version.  SBUS is a little snapper than CPPM.

Voltage Levels Unknown
I really have no idea when I'm flying the QX90 what the voltage levels are and when it's time to land.  There is no buzzer on the aircraft.  I didn't notice a second antenna on the receiver so I don't believe there is any telemetry.  Probably the best to know when it's time to land, once you get your aircraft configured the way you like it, is to set a timer on your transmitter. Set an audible alert after 3-4 minutes of flight time or whatever is appropriate for your aircraft.

Ok, I have covered some of the features I don't like and some I like.  Now I'm going to tell you what I'm doing to improve my QX90.

3-Bladed Props
The aircraft ships with 2-bladed props and it's quite fast but a little difficult to control.  First I'm ditching the 2-bladed props and moving to 3-blades.  I don't care about the top end speed.  This drone has plenty of speed.  I'm looking for more precision flying in tight spaces.  On my 250mm acro drone I fly with 6-blades and it fly's like a Ninja, very locked in feeling and precise.

New Camera
Next, I'm ditching the stock camera and replacing it with a better after market integrated camera and transmitter.

I'm ditching the stock motors and going with a set of 3.3v 17k rpm high output motors.  It could be this is not necessary and upgrading the props will improve flying.

I'm thinking the 680mah batteries are too big.  I had some extra 380mha batteries around that I used for a Hubsan X4.  When I tried these smaller batteries it seemed to fly better.  I'm not firm on this for now.  I still need to do more testing.

Purchasing the extra gear blows the $60 manufacturer price point.  From my perspective I'm more interested in tuning this platform to make it fly more like my larger drones than saving a few dollar.  I like the idea of flying inside the house, super cool.  However, I really want something super precise I can fly easily down a narrow hallway or fly super slow and stable.  After I get my new gear I will post an update to let everyone know if this fly's better.

Friday, August 19, 2016

Impressions of Furious FPV True-D Diversity Receiver

One word, awesome!  You can grab yours on the companies web site,  The gear in this hobby is changing so fast it's difficult to keep pace.  Not long ago I wrote an article describing a diversity receiver build out I did using a small camera bag, Portable FPV Microwave Ground Station in a Backpack.  Now the Furious FPV module that fits into my Fatshark goggles eliminates the need for a backpack full of electronics.  I'm still carrying the backpack but now I can haul more batteries, water, etc.

I like having diversity with the lightweight benefits of google flying.  The quality is similar to my ImmersionRC Duo 5800 V4 without all the extra bulk.  I don't have any of the diversity video to share just yet just sharing a few initial impressions.

REVIEW: SJCAM S5000+ Sports Action Camera

This is going to be a no nonsense review of the SJCAM S5000+ for suitability and use for photography on your multirotor aircraft.  After my S5000+ arrived I strapped it my Vortex 250 Pro and went to the field to try it out.  Here are my initial impressions from my flight.

Camera Size
The camera is a ever so slightly larger than it's earlier predecessors.  While it is a small camera, especially without it's protective case, it must be small and lightweight for use on multirotor aircraft.  There's not that much room on a 250mm aircraft.  Once I have the camera strapped into the optional GoPro cradle there is about 1/4" between the front rotor blades and the camera.  During a hard landing the camera shifted slightly.  After repositioning the aircraft for another flight I neglected to check the camera position.  One of my blades was trapped against the camera and would not turn.  I'm lucky I didn't burn my motor out.  It's not a big problem now that I know about it but another line item for me to check on my pre-flights.

Another concern is that there is only I place to put a wrap strap to hold the camera the mount and sometimes it presses the button while in flight turning off the camera.  I missed recording several flights that day due to the camera being shutoff.  At first I thought it was a configuration feature to shutoff the camera to save battery power.  After some careful review of the options this turned out not to the case.

Finally, I had the battery door on the bottom of the camera fall off on several flights.  In all fairness, flight is a demanding environment and it's easy to pull a lot of G's in an aircraft, corning, loops, crashing, etc.  I never lost the door but it popped off and I had to put it back on.  No doubt SJCAM could make some improvements designing cameras specifically for mutirotor rotor but I think ImmersionRC could also improve it's cradle design.  The design of the camera cradle on the vortex is two vertical carbon fiber plates that fit into the top of the aircraft.  The vertical plates are stabilized by a carbon backing plate.  A piece of neoprene with adhesive on the back keeps the camera from sliding.  A slightly better design in my opinion would also include a small carbon plate across the bottom with another piece of neoprene.  The extra neoprene would keep the camera from sliding and door would not pop off the bottom.

Image Quality
Amazing!  I took a quick video while setting some PIDs on my Vortex 250 Pro.  The camera will do 4k.  However, I am mostly interested in 1080P.  I set the camera to record 1080P at 30fps which it can do very easily.  No lagging or ripping, jello lines, etc.  I'm really REALLY happy with the quality of the video.

Better Auto White Balance
Almost forgot, previously one of the problems with small cameras is that when flying into the sun many cameras will darken the entire picture to compensate for the bright sun.  The result of this balancing war is that the sun looks great while everything else in the picture is so dark it cannot be seen.  Of course this is not very practical for sharing video with your friends and family.  You don't need to worry about this with the 5000+.  The camera adjusts to the light perfectly without adjustment.  When flying into the sun the camera reduces intensity of the sun while keeping foreground and background the same.  Watching my old camera raise and lower the intensity of the screen is annoying.  This feature alone is worth the price of a new camera.

The camera goes for about $139US.  Price is outstanding.  There is some competition in the space.  I can't say how well these compare.  GoPro is definitely the gold standard for sports cameras but cameras like SJCAM are edging in.  At least with 1080P, the difference in quality between the 5000+ and the GoPro Hero 4 Black is marginal - my opinion.  Especially, if your a new pilot and crash a lot.  ;o)


Monday, August 15, 2016

Patching ImmersionRC and Starting PIDS for Success

I wanted to follow-up with this post for some of you that may be considering or in the process of patching software on the ImmersionRC Vortex 250 Pro.  Please, stop and read FIRST.

ImmersionRC has made a very admirable attempt to make flying racing drones much easier.  And believe me, I have built two racing drones before purchasing my Vortex and it's an amazing piece of gear.  So don't wring your fists at ImmersionRC just yet.  It's likely if your having problems during patching there there's probably nothing wrong with your Vortex hardware.  I think where ImmersionRC falls a little short is in their documentation and even they have admitted as much.  Let's get on with it.

To be successful there are a few pieces of information need to learn that are not covered in the manual.  It may be the type of stuff that's obvious to expert multi-rotor builders but it's worth covering for everyone.

The Problem
Like me, you may have built a few drones on your own.  Because the Vortex has many of the components in common with DIY drones like flight control software and hardware you may be inclined to patch the Vortex like you patch your other DIY aircraft - but don't.  I have spent the last 2-days frustratingly trying to patch my Vortex like other aircraft I have that use Cleanflight and Betaflight.  In my case, I would patch the flight controller with Betaflight in the usual way.  Next, I would fire up the Betaflight Configurator desktop tool, configure my transmitter, my PIDS, etc.  Each time I changed some options on the configurator tool I would switch screens in the app to another screen and then return to the screen I made my changes.  Usually this is a good test to see if the values have been saved in the flight controller.  Each time you change a value, move to another screen, and return to the screen where you changed the settings it forces the configurator to load the settings from the flight controller again.  If the values are the same as you changed them then they have been "burned" into the flight controller.  In my case on the Vortex, I would apply some changes, check them in the way I describe.  To be extra sure my values where saved I power cycled the aircraft (unplug/replug battery).  When I returned to the configurator and open the last settings screen where I made changes I discovered the original values where stored not the values I set.  Essentially, the aircraft would forget all my settings if powered off.  I was not sure what to do.  I thought the problem was bad versions of flight control software or differences in the configurator vs. flight controller version.  None of this was a problem, it turns out the Vortex is trying to make setup easy for us and in the process of making things easy during setup if you attempt to configure flight control software as usual you will be frustrated.  I realize I have probably covered the problem in a little too much mind numbing detail but I wanted to put some bread crumbs out on the Internet in the event others are suffering from similar problems.

The Procedure
Keep in mind, this works well around the time of this article but ImmersionRC could improve the hardware in the future.  To restore all software on my Vortex 250 Pro to a known working state I did the following.

1)  Install ImmersionRCTools on your desktop
2)  Install the latest version Baseflight Configurator.  I have only used Baseflight.  I hear some on the forums using Cleanflight but I have not used it on the Vortex myself.
3) Install Baseflight/IRCFUSION3 flight control software on the Vortex.  Don't bother configuring it yet.
4) Install OSD on the Vortex using ImmersionRCTools
5) Use your FPV goggles to configure your Vortex with your transmitter.
6) Power cycle the aircraft
7) Now you can enter the Betaflight Configurator to set, flight modes, PIDS, etc.  Keep in mind, not all settings can be changed since they are configured by ImmersionRC's OSD.

Known working software versions include
Vortex 250 Pro (Ummagawd edition)
Betaflight/IRCFUSION3 2.7.1
Betaflight Configurator (latest version)
*Version 29 is not available publicly on ImmersionRC's website - to my knowledge.

Vortex 250 Pro
Betaflight/IRCFUSION3 2.8.1
Betaflight Configurator (latest version)

Starting PIDS
I'm not sure why good Vortex 250 PIDs are so damn hard to find.  Ordinarily sharing PIDs does not make too much sense for DIY racing drones.  Everyone's builds are just different enough so someone else's PIDs will probably not be too helpful anyone but that's not the case with Vortex.  We all have the same aircraft with some minor differences.  The weights of antenna's, differences in batteries, etc.  However, if your going with ImmersionRC's recommended setup of a 1300mAh battery then these PIDs will be a good starting point.  Please, please, please, write down any settings before you change them so you can easily roll back.

       P    I    D    RC Rate   Rate   Expo
Role   31   21   16   1.0       .47    .75
Pitch  36   23   16             .47    .75
Yaw    91   45                  .47    .75

I developed these over time and it seems reasonable it will work for others.  My son has the Ummgawd edition and it was a good starting point for him so it works for both 5x4x3 and 5x4x4 props.  You may need to touch up the settings slightly for flying 2-bladed props so iron out the vibration but it should fly ok.  I do fly with a little more expo on Taranis transmitter so if the aircraft if a bit sluggish you may want to bump up the expo to your liking.  Enjoy!

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