High Quality Bixler 1.1 Build (APM2.x)
This article describes a well planned Bixler Build (by Dave Smith).
This wiki page is a work in progress and will be completed as the information becomes available.
I have seen some really horrific pictures on the internet of Bixlers with everything taped to the outside. After digging through the internet, I found the answers I needed to build my plane, but the learning curve was pretty steep.
Hopefully I can help somebody out and save them a lot of frustration by logging my whole build.
The equipment list
- Bixler 1.1 ARF (HobbyKing)
- Motor (HobbyKing)
- ESC (HobbyKing)
- SBEC (HobbyKing) - (Optional)
- ESC Programmer (HobbyKing)
- Motor mount (HobbyKing) - (for spinning bigger props)
- APM 2.6 with separate GPS/compass
- Radio: Spektrum DX8
- Receiver: AR6210, no satellite
- Prop: APC 7-5. The HK 7-5 prop came with horrible adapter collars and I do not recommend them!
- 25cm 4 position cable (store.3drobotics.com)
- 25 cm 6 position cable (store.3drobotics.com)
- 5 pin housing (www.digikey.com)
- Female-female server extension (15cm x 7 qty) (store.3drobotics.com)
- I am waiting on my new air-frame after an unfortunate incident with
an electrical wire on a windy day.
- Part of the learning curve, which I will not elaborate upon thoroughly to spare you the anquish.
- Before I knocked the tail off, I had my plane hitting waypoints, loitering, RTL, and auto-landing.
- For now, I will show you what I did with the electronics.
- I do not have telemetry yet, so I just used the stock PID settings and added some I gain. (More on that later.)
- About using an external SBEC: I chose to do this because I am an RC
heli guy, and I often use servos that draw ridiculous current.
- If you power the servos separately from the motor, there is less chance of either one shutting down due to over-current draw.
- But you also add a second electronic device that can fail.
- When the motor is at max throttle and servos are fully deflected, such as on a windy day, the separate BEC gives you some headroom.
- I will post pics of the air-frame assembly when I receive it next week.
Programming the ESC
Set up the programmer card as follows:
- Set the low voltage cutoff to its lowest setting to allow the APM failsafe feature do its job.
- Don't worry about FWD vs REV; you can just switch two of the motor wires if the motor spins backwards.
- Connect the ESC to the card and the motor (no prop).
- Plug the ESC into a battery and you should get one tone from the motor, letting you know that programming is complete.
- Disconnect the programming card and then the battery.
Wiring the ESC and BEC
I chose to use EC3 connectors in my build, because all of my batteries have them. XT-60 are just fine.
- Cut the servo power lead off of the BEC at the connector.
- Solder the BEC power cables along with the ESC power cables into your
connector (this can be a little tricky).
- Get the solder hot in a connector and insert an ESC wire.
- Keep the connection hot and slip the BEC power wire in next to it.
- I chose to run my servos at 5V from the BEC.
- There is a jumper on the end of it that lets you select 5 or 6 V.
- Before you reinstall the electronics secure the jumper on the BEC with a glob of hot glue or shoe goo.
- Pull the center (red) pin and wire from the ESC receiver connector.
- This disconnects the built in BEC from the ESC. You don't need it since it is only powering the motor.
- Tuck the ESCs BEC wire away with heat shrink tubing over the end.
- You will need access to it if you need to re-program the ESC.
- Add 100mm 14 gauge motor lead extensions with 3.5mm banana plugs to make it easier to wire the Bixler's motor later.
Here it is ready to go:
Mount the APM and install the wiring
- Make a 45 x 100 mm mounting plate for the APM using 5mm plywood (or plastic or fiberglass board).
- Use a 1" square of Kyosho Zeal Gel or Dubro foam under each corner of the flight controller to provide vibration suppression.
- Zeal has high strength double sided adhesive, but if your pads do
not, consider using "Welders Glue" available at Amazon or Lowes.
- Re Welder's Glue: it is contact cement. Lightly cover each surface you wish to bond and let them dry for about five minutes.
- Then carefully align and put the two surfaces together and for immediate bonding.
- I will also use Welder's Glue for assembling the foam air frame and building an access door in the fuselage.
The APM mounted on the plate: (Pictured are the stock cables to the GPS. I will actually be using the 30cm cables)
Preparing the Fuselage
- For this build, the APM is mounted inverted and we want to get it level with the fuselage (level with the line of flight).
- You can see that the wing has a positive angle of attack when the APM is level.
- If you just stick the APM to the bottom or top of the fuselage it will not be level, which may affect performance.
- I don't like to take chances, so, I removed some of the foam below the top inside of the fuselage to get the APM level:
- Here is the APM set in place with some of the components.
- At this point you should mark where your access panel will be.
Trimming the Fuselage
- I originally cut too much and the fuselage was really weak.
- No problem; with some hot glue you can easily fix any boo-boos.
- In the picture below you want to cut the lower portion and leave the area I have labeled "Do Not Cut".
- You will have ample room to access the APM Inputs and Outputs, as well as the USB port and other pins.
- Cut straight through the foam so that the panel will open easily.
- Now match up the two halves to mark the cuts for the right side.
- Cut a larger access panel out of the other (right) half of the fuselage so you can access the USB port on the APM.
- Cut a bevel along the long axis of the large panel we already cut out.
- I think that my picture is incorrect below; make this cut on the panel from the right half of the fuselage.
- This is not the edge where the two halves of the fuselage join, but the cut near the wing.
- Now, make a Welder's glue hinge where the bevel (that we just cut) meets the fuselage.
- This creates a hinge for the panel that is invisible and super cool.
- Don't worry, custom foamies use this type of hinge for hundreds of flights.
- Here is link to a YouTube video explaining how to make a Welder's hinge:
.. youtube:: S-8PGFJqqMM :width: 100%
- The panel should look like this when the Welder's hinge is complete:
Assemble the Fuselage
- So now I am going to fast forward a little bit.
- Follow the Bixler instructions and glue the halves of the fuselage together.
- Again, I use Welder's glue, applying a thin bead to each half, letting them get tacky, and then assembling the halves.
- Run the motor cables from the ESC to the motor before you assemble the two halves.
- No worries if you don't, but it will save you the trouble of trying to attach the motor leads with needle nose pliers and hemostats.
- You should also check the rotation of the motor so that you do not have to switch motor leads for a motor spinning in reverse.
COMPONENT Installation Details
- Below I have the fuselage glued together and the components glued in place.
- I like hot glue for this detail.
- Notice that I glued a 3mm carbon fiber rod across the access hatch for added rigidity.
- At this point, space is becoming a concern.
- You will notice that we have put nothing in the nose so far, and all of our components are pretty tightly tucked under the wing.
- I did this so that we can utilize bigger batteries in future builds.
- This time around I am using an airspeed sensor which is recommended, but not necessary if you are on a first-time build budget.
- To make space for batteries, I mounted the airspeed sensor board and receiver to the bottom of the canopy hatch:
Complete The Construction
- Use a servo splitter cable for the ailerons, I got odd results when programming separate aileron servo on its own channel.
- I am quite happy with this setup because you can get the CG perfect with Zippy 2200mAh Lipo batteries.
- I mounted the GPS/Compass on the right wing after removing just a small amount of material.
- I mounted it with hot glue and taped the cables in place with 3M Blenderm tape.
- I like Blenderm because it sticks well and is flexible.
- Having it sitting up high on the wing is not ideal, but I wanted to get it away from the fuselage and all of the current-carrying electronics.