Friday 20 July 2012

First sucessfull flight

Yesterday I went for a second attempt to fly. The weather was still bad, but we got a little break and my testing pilot has a lot of Bixler experience and felt confident.

This time everything worked incredibly well. The plane flew like on rails, in AUTO and in MANUAL. It managed to fly some very hard turns very safely. I have great confidence. And it does not look like any tuning will be required.
Except for cruise throttle. The flight duration was very short. That was probably mainly due to a unnecessarily high cruise throttle speed.

I flew here
http://binged.it/NCYHBS

Thursday 28 June 2012

Resumee of first flight

First of all, my initial assumption that the elevator servo was inverted was wrong.

I found several issues though.
  • Elevator neutral in the Servo section was biased towards diving.
  • Gyro sensitivity was set to 1. Which is absolutely wrong.
Stabilisation is mainly a Gyro thing. And my gyros did not work thanks to my idiotic default value. It took more than five seconds for the IMU to 'sense' new headings.

Tuesday 26 June 2012

First flight

Yesterday we had the first flight of the Bixler airframe (flies very nice) and the first flight in AUTO (not so nice).

First I noticed that I had the aileron serovs reversed. Quite idiotic that I never realized that earlier.
Then I noticed the same for the elevator. But I never checked if that was the radio or the autopilot. I just reversed them in the <servos> section.

My pilot approached the test area nice and stable but a little bit low. Too low as it turned out.
Soon as it was in Launch mode it started diving full throttle into the ground. The pilot had no chance to catch that.
In retrospect it's clear that we should have expected that and should have done that at high altitude.

I still have to investigate the cause. But I think the elevator channel was reversed in AUTO.

Damage report:

  • Belly landing at high speed.
  • Cockpit ripped into pieces.
  • Motor and motor mount ripped off.
  • GPS flew off and the helical antenna broke off.
  • Camera mount snapped.
  • Lost tail wing
  • Front foam severely bent and snapped.
All in all it's fixable. She will be flying again in a few days and a few pounds of hot glue later...

Wednesday 20 June 2012

Recent Progress - Cockpit wiring [With pictures]

I finished my cockpit and wiring based on this neat HobbyKing product http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=22731

I'm quite pleased with the result. I just had to cut a window in the back firewall and some mounting holes for the Lisa board to make it UAV ready.

I also added a super cheap mini keychain camera which currently sells for £10 on amazon.
No live FPV with that. But I should get some nice recordings.



Recent Progress - Bixler Airframe tuning

A post from me asking for some kind of clean starting point for my aircraft file turned into some nice effort for a Bixler based standard template for others to use.

It still needs tuning. But this is great news for beginners.
The Bixler is cheap to buy and versatile.

This is the location of this file https://github.com/paparazzi/paparazzi/blob/v3.9/conf/airframes/examples/bixler_lisa_m_2.xml
Thanks Felix.

Recent Progress - Possibly stable XBee Telemetry

I still have great issues connecting XBee.
But it seems that if I reset the ground station radio shortly before I power up the airborne ratio I have a chance of getting a sync.
If it holds for more than a few seconds it will hold forever.

Still not happy with it. But at least there seems to be a chance that the radio itself is not broken.

Recent Progress - Stable Spektrum satellite receiver

My Lisa/m always crashed when I tried to bind my radio.
I recently found the solution. The interrupt handler for the URART which the second Satellite is connected to needs to be overwritten.
<define name="RADIO_CONTROL_SPEKTRUM_SECONDARY_PORT" value="UART5"/>
 
Felix Reuss came up with a way to make this better
http://paparazzi.enac.fr/wiki/Subsystem/radio_control#Spektrum
Now only this is needed.
<configure name="USE_SECONDARY_SPEKTRUM_RECEIVER" value="1"/>