Archive | February 2014

Bixler Mod – It flies!

Took the Bixler out for it’s first flight with the ArduPilot on-board and had few very good flights. I had a bit of issues initialising the airspeed sensor correctly. One init, it showed around 20m/s while on the ground (I don’t think the Bixler can go that fast, ever if it tried to!) and on another occasion it showed zero airspeed throughout the flight.

This is something I’ll have to watch carefully as it does not navigate automatically if this sensor is not working!

However, once that was working it navigated very well. Airspeed and XY position was very good with it hitting each waypoint that I set for it. Airspeed was kept within around +- 1m/s. I’m not totally happy with it’s height accuracy, it lost around 10m on the downwind turn every time. The new speed and height algorithm they use now is new to me and I need to see if I can tune that a bit better. Thought 10m is not THAT bad, considering that it was a very tight waypoint pattern and that it will usually not turn that much during navigation.

See the screenshots below for the recorded telemetry tracks.

APM Planner view of track.

APM Planner view of track.

Google Earth 3D view of track.

Google Earth 3D view of track.

Bixler Mod

I added FPV gear to my Bixler for no-nonsense FPV and had really good results.  So good, in fact, that my problem now is that I have great video at ranges that I’m not comfortable flying at without RTH and/or an OSD.

So, all my resolutions of keeping the Bixler no-nonsense have flown out the window and the Bixler is getting modded!

I’m adding an APM2.5 with Minim OSD.  While I’m busy, I have switched from the regular Turnigy receiver to an FR-Sky telemetry receiver that is now moving into the tail.

The Bixler’s wing attachment mechanism have always irritated me, so that is changing too.  The wing is now attached from the top using big nylon screws.

When I’m done, it should have full autopilot with OSD for FPV, able to carry 2 x 2200mAh batteries in the nose (as all the avionics are now under the wing and in the tail, making more space).

However, I’ll probably have to look at the motor and prop setup before I’ll be comfortable flying with two batteries.

Here are some photos of the build so far.

Radio RX is moving to the tail:

Cut a bay for the Radio RX.

Cut a bay for the Radio RX.

Radio RX now sits in the tail.  Will make nice stalks to hold the aerials and will modify the aerials into dipoles.

Radio RX now sits in the tail. Will make nice stalks to hold the aerials and will modify the aerials into dipoles.

 

Wing now attach from the top:

Nylon bolts attaching the wing from above.  Much easier to remove.  Slotted out the foam above the motor wire conduit to make it easier to get to the bolts.

Nylon bolts attaching the wing from above. Much easier to remove. Slotted out the foam above the motor wire conduit to make it easier to get to the bolts.

Belly cut open and now usable for avionics:

Access hatch cut in the belly.  AP will go in here.  Wire coming from the right is from the radio RX.

Access hatch cut in the belly. AP will go in here. Wire coming from the right is from the radio RX.

Looking into the now open belly up towards the wing.

Looking into the now open belly up towards the wing.