Bormatec Cam-Flyer Q

Seatbelt mode flight stabilization on Bormatec Camflyer

Testing conditions were perfect with gusty winds at around 4-5 m/s (measured) coming over nearby trees making manual flight reasonably challenging with the small CamFlyer Q but a breeze (no pun intended) with Seatbelt Mode.

It has just 80 cm / 32“ wingspan.

Video Highlights:

  • 1:40 min: watch things go wild as seatbelt is tuned off
  • 3:40 min: flying at tree level (turbulent) with seatbelt off
  • 4:15 min: going from seatbelt off to on and flying at tree level again
  • 5:00 min: three landing in seatbelt mode all the way to the ground with the last filmed from the ground as well

Power System / Propeller / Servos

Motor

Recommended motor specs: > ~900kV - 2200kV, ~ 20A peak, 3.17mm shaft

  • Recommended: Hacker A20-30M 980kV with a fixed 7×5” prop. This combination has been flight tested and is optimal for UAV use. Actual flight times pending but > 20min.
  • Low-cost: Turnigy D2826-6 – 2200 kV, comes with prop mount

Propeller / Prop Mount

Recommended size / type: ~7×5“ (18×13 cm).

Fixed

Propeller mount is included with motor.

Folding

  • Prop mount / Spinner: Multiplex Easystar 2 prop mount (MPX 733506, Eflight.ch)
  • Aeronaut CAMCarbon 7×4“ propeller blades (Eflight.ch)

Electric Speed Controller (ESC)

About 20A constant load and minimum 2A BEC at 5V are recommended.

Battery

A 1300 mAh / 25C battery is sufficient.

Battery Connector

The PX4 project recommends for all aircraft and multirotors the XT-60 connectors, as a range of batteries is available with them and 3D Robotics offers all power connections with it. It is slightly better shielded and easier to unplug compared to Dean's Ultra.

Servos

A 9g / 1.3 Nm servo type is recommended, a total of two servos are required. Since an autopilot does move servos more often and its accuracy depends on accurate motion, digital servos with metal gear are recommended.

Rudder Horns

FIXME

The standard rudder horns are acceptable, but have not a very wide footprint and tend to bend the foam.

Wiring

Pixhawk port
MAIN 1 Left elevon
MAIN 2 Right elevon
MAIN 3 EMPTY
MAIN 4 Throttle

Kit Contents

This is what you get if you order full kit:

Make sure you have the last manual which you can find here. The one delivered is not always the most recent!

The propeller provided seems pretty useless so it is recommended you get the replacement propeller listed above.

Assembly

Install servos in the wings. Use something to make a hole from the pre-made slit in the wing for the servo wire through to the root of the wing on the other side.

Getting the servo lead is a little tricky unless you make a big hole. Alternatively, you can tie a piece of string to the push rod wire (on the z-shaped end of it) that came with the plane and pull one end of a string through. You can then tie the other end to the servo lead and then carefully pull it through. Be gentle as you don't want to damage the wires.

Once the wires have been pulled through it should look something like this.

Put a little, not too much as you might want to get it out one day, foam safe glue (CA) on each side of the servo, push it into place and push the servo wire down into the slot.

Attach the motor mount to the motor with the four small screws that come with the motor.

Fit the motor plate onto the rear of the fuselage using 5 minute Epoxy. If you want you can already drill the holes into the plywood before glueing it to the fuselage using the motor mount as a template for the holes.

Drill holes in the plywood motor mount to make it easier to put the screws in. Attach the motor.

Reinforce Elevons

To stiffen the elevons you have at least two options. You can either apply a contact glue such as UHU Por, wait till it is dry to touch and then apply fiberglass reinforced tape or, as shown here, you can install a 2mm carbon rod.

Fiberglass Tape Method

Use 50 mm / 1.8” or wider tape. First apply it to one side of the elevon, make sure to apply it with pressure. Fold it around the back firmly and make sure to not leave any air bubbles and have it completely straightened. Use UHU POR or CA to fix the ends. The final result should look similar to the picture below.

Carbon Rod Method

Draw a line diagonally across the underside of the elevon. Cut a slot out using a knife or a small drill angled so it works like a cutter. Push the rod along into the slot moving it backwards and forwards to get just the right depth and to smooth out the groove. Test fit it and make sure it fits flush with the elevon surface.

Apply an good amount of CA into the slot so it will flow around the rod. Push the rod into place and apply CA Kicker if you have any (otherwise a good dosage of patience if you don't).

Mount the Servo Horn

Use some contact (UHU Por) glue to fix the servo horn in place once you have aligned it.

Once you are happy with the alignment you can put the screws through and into the flat white plastic piece that goes on the other side of the elevon.

Glue the supplied velcro strips into place to hold the nose piece in place.

Let's mount the PX4. The easiest way to get the hole positioning right is to leave standoff screws on the PX4 and just press into the foam. After that you can just remove from the board and push them down into the foam. After that, pull them out again and apply a couple of drops of glue (CA) and re-insert them.

Next, attach the standoff screws to those embedded in the fuselage.

Attach the PX4 to the standoff screws.

Important: The combination of servos, receiver, PX4FMU and PX4IO draws too much current if you are only powering the PX4IO from the Lipo via the battery connector. The best setup is to connect your Lipo to the PX4IO battery connector and provide power via the ESC to the servo header. Alternatively you can power everything via the ESC alone.

The PX4IO power connector soldered into the bullet connectors that connect to the Lipo.

Put some velcro in place to hold the receiver and ESC. In this picture you see it is mounted on the wing root. You can also place both the receiver and ESC flat on the fuselage if you prefer (see photos further down).

Balancing the wing at the recommended 120mm behind the leading edge.

Top view showing the GPS and XBee in place.

All wired up and ready for the first bench test.

Balance prop FIXME

Take the 7×5“ APC E propeller and put the marked ring into the center (if it fits the aluminum prop mount, try before use).

APC E Prop

First Flights

On the field, right after the first flight.

And here is a video of the first test flight. This is currently bypassing the PX4 and using the receiver directly. The next flights will use the PX4.

Further videos:

  • Second test flight video

Build Log

This is work in progress.

Hacker Pusher Configuration

Spinner Mounting

Servo Lever Mounting

Servo / Horn Mounting

Electronics

Electronics Mounting

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