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Posted by Jem3 | Jan 16, 2015 @ 07:57 PM | 9,458 Views
My test bed was an old Gaui 330. That Gaui FC only had gyros, so it tried to keep the craft from *changing* orientation. It obviously couldn’t have a ‘self leveling’ feature without accelerometers. Using a 6 degree cant, I found a distinct, though small improvement in remaining level while hovering. I did find out though, exceeding a certain amount of tilt, such as when flying forward fairly rapidly, or flying into a strong wind, that a rapid loss of self-righting occurred. My guess is that occurred when the prop went from an aerodynamically stalled condition to being under load as the apparent wind direction went from under to over the blades. (Stalled in this context means the prop disk isn’t moving into undisturbed air - look up “why are fixed wing props different from multi rotor props

Lets use ‘Thrust’ instead of ‘Lift’, as Lift usually denotes a vertical force, compared to a horizontal ground. ‘Thrust’ may be in any direction. If a thrust is vertical, we can call it lift.

Lets also use ‘Weight’, as it is a force which equals an objects’ mass times the acceleration of gravity.

So with these definitions, we can draw force vector diagrams that are dimensionally consistent.

“So what we’re gunning for”, as my mechanics professor would say, is the net, or resultant torque about the center of mass (or CoG for those who like that term) when the quadcopter with rotors canted inwards 15 degrees each, has been tipped 15 degrees counterclockwise.

If the result...Continue Reading
Posted by Jem3 | Sep 05, 2012 @ 05:52 PM | 3,569 Views
I thought I'd post some pics of the wrap up of this project. An issue was fitting the A490 into the tilt frame with the mini USB connector installed. A tricky little bit of X-acto work, micro soldering and silicone did the job. In removing the plastic outer part of the plug, you will invariably cut a wire, so soldering is needed. Check the solder connections before applying the silicone. (If you're extremely skilled or lucky and don't cut the black or red wires, all you have to do is the silicone job).
Posted by Jem3 | Aug 17, 2012 @ 04:21 PM | 5,715 Views
What hardware you need
• Canon A490 - $15 to $35 on Ebay
• a 4GB (class 10 is best) SDHC card - see discussion below - $7
• An adapter for an SDHC card - to be able to plug it into your computer - a USB adapter about $12
• a mini USB cable - that you'll modify
• a servo channel operated switch $7 to $20
• 3.5 mm stereo cable for live view to FPV transmitter
• a momentary push button switch (normally open is easier to use) $3

What software you need - and how to get it
• CHDK (Canon Hackers Development Kit) software to run on the camera's computer. Links to files of CHDK to download are here, both "stable" and "development".
• Utilities to run on a PC to format the SDHC card in a specific way to make CHDK available to run on the camera. The applications Cardtricks, or SDMInst.exe, are used with Windows OS, and SDMInst for Mac OS. There are also utilities for Linux. For installation information and instructions, see the supplement to this User Guide:
• Utilities to determine version and rev of camera's firmware, there is a number of ways to do this. Go to the homepage of CHDK (Canon Hackers Development Kit) most of the resources you need, or links to them are here.

What to do
I decided to use a Mac, as the ACID software makes it very simple. Here's what I did.
* Go to Dave Mitchell's Zeno site
http:/...Continue Reading
Posted by Jem3 | Aug 14, 2012 @ 12:37 AM | 3,798 Views
Gimp 2.8 and GoPro wide-angle correction
Some people like the GoPro stock lens look and others don't. Many times it depends on how the scene is framed. Here's a package that lets you change a little or a lot.

I came across a reference to GIMP posted here quite a while ago - a GNU (shareware) image manipulation package that runs on UNIX machines, or Unix layers on Mac and Windows machines. The old reference was for Gimp 2.6 - the current is version 2.8.0 - so I thought I'd resurrect the reference for those who don't know about it. Below images taken with GoPro 1, with original lens in watertight case. Yes, they're terrestrial, but show the possibilities quite clearly

available at:

Updated menu selection
Filter ->Distort->Lens Distort
I used parameter values of
Main -64.8
Edge +16.43
all others left default a zero

If centerline of FOV is not perpendicular to subject of interest, you might want to consider adjusting the perspective to make parallel lines look parallel.

Updated menu selection
Tools->Transform Tools->Perspective
Parameters depend on subject