I’m reaching the stage where I think Phoebe is just about all she can be.  I need to get a video to prove it, but her recent flights have been (mostly) safe and consistent.

And I’m already planning what short term upgrades I’ll do next.

  • reinstating her legs – the dome ball on the underside has saved me a fortune in broken legs and propellers due to aborted flights, but now her behaviour has improved significantly she can have her legs back – I actually like the soft sponge dome but it stops me from…
  • putting her WiFi antenna back between her legs to get better reception – currently she’s on a nano dongle and I only get about 5m coverage
  • customizing the RPi.GPIO.wait_for_event() code for performance reasons.  This will allow me to wait on the MPU6050 data ready interrupt and hopefully improve the code response to availability of fresh sensor data even if only marginally
  • moving to a model A+ when available due to it’s more efficient power usage, and layout which allows…
  • fitting a custom PCB akin to a breadboard attached directly to the GPIO pins and the standoff holes.  This will reduce weight and lower the MPU6050 nearer Phoebe’s center of gravity which in turn means that rotation doesn’t trigger the accelerometer, and hence greater accuracy.

None of these are radical changes and they are already in progress.  I’m hoping I can complete then before early September so I can show her off at the next CamJam.


2 thoughts on “Spoilers!

  1. Just curious. The specs for the DJI FlameWheel 450 say it’s between 800gm and 1600gm, according to BuzzFlyer, http://www.buzzflyer.co.uk/DJI-Innovations/DJI-FlameWheel-F450-ARF-or-RTF/p-182-2165/
    I originally couldn’t find that spec and was advised by DJI that the Payload should be between 800gm and 1200gm.
    So, how heavy is Phoebe now?
    Also puzzled about the range you are seeing from your wireless adaptor. 5m seems a very short distance. The spec for wireless b/g should give up to 100m outdoors. I’m not aware that the dongle you are using has any particular restrictions in that area. Certainly when I have used them I have not had any problems compared to other USB devices. May have miss-understood exactly how you have the wireless comms set up.
    Of course, my rough calculations say the total length of a half wave dipole ariel in the 2.45GHz band should be about 6cm, and the package for that dongle is very small 🙂
    Footnote: I was doing some experiments with wireless networking two or three years ago, and bought a couple of the ‘White Box’ wireless b/g adaptors from Maplin. When I opened one up I discovered that it came complete with a connector to attach an external ariel. I also found a Belkin adaptor which was very similar internally, down to the solder pad for the ariel connector to be mounted on. Unfortunately, I don’t think you can guarantee that all the adaptors under a particular model number will have the same feature. You would have to get an adaptor that specifies the feature to be certain.

    • How impudent! One should never ask a lady her weight. 🙂

      However, as you did, Phoene weighs about 1.4kg. Well within range of an F450 + payload, and infact she has better motors and props so could probably take a lot more, but keeping her light makes for longer flights, and reducing the height of the sensor aligns them better with the frame centre of gravity – doing so keep rotation from affecting acceleration.

      Before I added the sponge dome, I used a dongle with an SMA-RP connector so I had a 3dB antenna underneath her – connectivity was great. With the dome, I’ve got one of those nano-dongles, and it seems very directional – hence my wish to get legs and antenna back on her.

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