Beauty crash. Every day has ended in a crash since the last blog post. Had the propeller mounting bolts come loose. Had battery voltage suddenly drop to 9.11 & a complete loss of attitude control.
Found cyclic integral isn't resetting between autopilot flicks.
Attitude hold mode is a joy to fly manually. She flies like the Corona again. Very stable & more visually satisfying than a bunch of symmetric propellers.
The helix was extremely noisy & random so it was time to try different orientations. The vertical orientation proved 2 satellites worse than the horizontal orientation. Unfortunately it is not completely omnidirectional. The only difference was from positioning the module on the nose.
Overall, the helix is getting 4 fewer satellites than the patch though its satellite count is more stable than the patch. If the module is mounted where the patch was, it's completely worthless. It's extremely fragile & really hard to mount. All roads are leading back to different mounting locations rather than different antennas.
No more sunny days until 2011, but there's always a party in Cloudyvale. This time it's another ducted fan VTOL that didn't work. Suspect control surfaces were too small & PWM was 50Hz. So basically, photos taken when recording video have the same resolution as the video.
Relations with the Air Force turned slightly better last Saturday. We'll see how that goes.
Funny how US is going in the exact opposite direction to the rest of the world in aerospace. Maybe you'll still get the Lady Gaga helipad.
Comments
I did a lot of flying with acrobatics planes and was amazed how well Ublox (vertically mounted) tracked the flight. Not the same with an EM 406 (patch).
I'm wondering if you could do a comparison simply changing antenna position. This comparison should be done with two modules running at the same moment. If I understand right you did not made it this way, isn't it ?
You sure know that satellites constellation changes a lot during the day, with very good moments and very bad ones, thus the inaccuracy of a test done this way.
I generally agree with Alex on the usage of helix antenna (135°) vs. patch (~30°?)
Best regards,
Ric
As I understand it, the helix for GPS works best when it is mounted in a vertical orientation. The helix is supposed to be better than the patch at low angles. Supposedly, the GPS specs call for tracking down to 5 degrees above the horizon and the patch antenna is not capable of satisfying this requirement. The idea is to have a hemispherical radiation pattern, which is why you want the antenna mounted vertically. So, maybe your approach should be to find out why it's not working in the conventional orientation.
Also, I've read that the best GPS performance (i.e., accuracy) is when the satellites are low on the horizon but widely separated in azimuth.