QuadPlane Conversion of Hobby King Bix3 Trainer


Sometimes the parameters change names or position in flash where they are stored. I have seen it when you don’t need to re-load parameters after a minor firmware upgrade and many times when you do need to re-load them. Sometimes, even the ACC and compass re-calibrations need to be done as well.


What sort of flight time are you getting with your Bix 3 Quadplane setup?

I am finally starting my conversion. I will be using a DJI E305 Quad set, a similar but maybe a higher spec than your motors. I am hoping that I can sling a small mirror less camera underneath.

It seems my hover current will be a max of maybe 16A, meaning I could maybe use a 7000 mah Li ion pack weighing 400g and putting out 21A max. This maybe would allow a Sony RX100 to be added. All a bit speculative–will need to validate this with a Li Po.

It would be nice to have a hybrid system that could blend the power from a small LiPo and a larger Li-ion pack. There are chips that do this http://cds.linear.com/docs/en/design-note/dn277f.pdf I wonder if Christian Mauch would look at this. Seems there may be a good use for this in this class of UAV.

Hi Marc,

I’m using a 4s 2800mAh Zippy 30C pack that weighs 10oz. The total flying weight goal was 58oz so I am close to that or a few ounces under. Since I built my Bix3 QuadPlane as an initial test platform, I used motors and ESCs I had on hand. I also choose the 4s Zippy Lipo pack because it was similar in size and weight to my stock 9oz Multistar 3s 4AH pack for balance.

My initial tests were focused on autonomous hovering modes and transitions so I never flew more than a few circuits as a normal plane in forward flight mode. My best guess is that I can at least hover for 5 minutes and fly for 5 minutes for a 10 minute flight. Obviously, the less time you spend hovering the greater the flight duration…especially during autonomous flights. My Bix3 isn’t currently set up to measure current.

I’m not sure how much the Sony RX100 weighs but you can use the APM Throttle MID setting as a sanity check and perhaps over drive your quad system knowing that your hover periods will be short (not like a copter).

My larger Ranger EX QuadPlane conversion has a Mauch PM as does my FireFLY6 so I can analyze flights better. One tool do to this is ExMaps. The link below is from my FireFLY6 test survey which used about 1/2 of my 6s 5200mAh pack.

Mapping Survey Test 2

An RX100 is 240g (sorry I fell for that Napoleonic racket, the metric system) but with some antivibration we are at 300g. My Nex5Rs are 500-700 depending on lens choice. Too much.

I will have a Mauch pm in the Bix.

I am hoping I can get a 4s LI Ion pack with 5000-7000 in there. This may all be infeasible, of course. In theory It can supply enough current to hover and the weight savings are substantial. My concern would be that it may struggle to land on li ions at 30%.The DJI escs and motors will have no issues though.

A 1500 mah backup battery to land would be appealing but it would need customized circuitry…

We will see… …

Ok I’m in, copying this excellent build slavishly (well sort of with what I have available)

Hi Gary,

The Bix3 makes for a great conversion to a QuadPlane because it is relatively light and has plenty of lift. Being able to remove the wing with two 90 degree twist screws is a real pleasure! The new Plane v3.8.0 firmware seems to working well for most.


It’s an older 2 that I have, along with some very dodgy motors the size of which I am not sure! Your write up is fantastic, thanks for taking the time.

I can’t resist publishing it. It’s a token of thanks to Greg Corey for helping so much and sharing his knowledge. I join in the thanks also :grinning:

FrankenBix, I love it! :slight_smile:

I have continued my Bix3 conversion thread here using Plane v3.8 firmware.

hai greg…i thought that the bix3 motor only support 3cells…

did u always full throttle or not…and is there any limitation for that bix3 motor… im still afraid to use 4cells lipo batt coz i read that the bix3 motor only support 3cells…

It worked on 4s for a season and was long enough to prove performance. The throttle was usually around 50% and there is good airflow around it. The stock motor quality is low and you have to deal with a cheap prop adapter so an upgrade like I did on the v3.8 thread extension link may be needed eventually.

how you setting the transition between quad n fixwing…

I typically change the flight mode from QSTABILIZE (or QHOVER) to FWBA (or CRUISE). I never use QLOITER except for initial quad testing to verify the BARO and GPS performance.

okay…thanks a lot man…appreciate ur replying my question.

hello greg ,
can you give a brother a help ?
im building Quadplane like you
do i change q_frame_type
to h_class ?
(my frame is like your setup )
how about the wiring of the motors and the servos and the esc calibration can you plz tell me your setup .

Hi Mohammd,

Welcome to the APM forums!

It’s tough for me to remember the details of a project from 4 years ago. Fortunately, most the information has been added to the APM WiKi in the QuadPlane Support section.

In my setup, the Q_FRAME_TYPE is set to 1 for X frame. Use the QuadPlane Frame setup section and Motor Order Diagrams to determine if your setup is X-frame or H-frame.

The ESC Calibration Procedure is also in the WiKi so spend some time reading through it or use the search engine to find things faster.

Good luck!

Hi there @GregCovey . This isn’t really an pixhawk question. More of a setup one. I was trying to replicate your first phase with my bix3. Two unfortunate things happened.

How do you keep the blades from cutting the wires of the GPS? I tried your setup but eventually the blades run so close to the frame that the wire on top of that got cut by the blades.
Talking about the propeller. Did you use the one that came bundled with the Bix3? I’m trying the out-of-the-box config with the recommended battery from hobbyking and that’s not even enough to get the Bix off the ground. I ran a few ground tests and tried to eventually take off but no luck. Not enough power to take this bird of the ground.

Hope you can help me out. You really are an inspiration.
Thanks in advance.

Hi Nuno,

You can cut a “V” into the foam and lay the GPS cable below the surface. Then glue it in place with Beacon Foam-Tac. Perhaps you can also slightly lift the aft end of the wing assembly to raise the motor pod.

The 9oz Multistar 3s 4AH pack balanced the stock Bix3 perfectly. The Bix3 QuadPlane conversion uses a ZIPPY Flightmax 2800mAh 4S1P 30C Lipo pack to start which weighs about 10oz. This information is in post 1 and 4, respectively.

I have continued my Bix3 conversion thread here using Plane v3.8 firmware.


Love this!!
I’m going to convert this to a QuadPlane:

I’ll take some of your really cool ideas, I keep you up to date with the process.

Thanks for the really cool and detailed information you provided @GregCovey