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Archive for June, 2010
Posted by Heli Hacker | Jun 30, 2010 @ 09:42 PM | 6,999 Views
Some interesting test results:

After flying the PhuFox for a while, and making a lot of software changes to the 2-axis PhuBar, I went back to fly the Phubee again, only to discover it no longer flies well with the same parameters as before but with the updated software. I had to increase the decay value to get it to fly right at a 45 phase angle, analogous to removing some weight from a physical flybar. And it flew MUCH better when I changed it to 0 phasing, like I am using on the FireFox. I hadn't changed anything on the heli itself, so it has me puzzled. I'm still trying to figure out what change I made to cause this. But regardless, I have settings for both phase angles that make the heli fly well.

So then I tried the PhuFox at 45 phase angle. After the above mentioned experience with the PhuBee, I figured I should increase the decay, so I set it to 100, about the same value as the PhuBee. 100 percent decay simulates a flybar that re-normalizes itself perpendicular to the rotor shaft in about 1.5 seconds following a change in attitude. It flew with about much better stability than it did with 0 phase and smaller (slower) decay value.

I need to think about what this means. It would seem to imply that the 45 phase allows a physical flybar to provide the same or better stability as a heavier flybar at 90. And perhaps give you stability without sacrificing as much responsiveness as a heavier 90 flybar would require??

One thing is clear. I now have a single set of gain and decay values that work reasonably well, though maybe not optimal, on both helicopters. This perhaps explains how makers of commercial electronic flybar units can program them with default settings that will work well enough to at least get a customer started regardless of what helicopter they have.
Posted by Heli Hacker | Jun 17, 2010 @ 02:42 PM | 8,550 Views
As great as the keychain video cameras are, there are times when they could benefit from some kind of viewfinder. When recording helicopter flights I find myself wishing I could keep things in the frame better.

When I was into high-power rocketry in the 90's, I had the same problem with my Sony 8mm video camera. When a rocket is traveling a hundred feet per second or more, if you lose it from your viewfinder, you may never find it again. I solved this problem by attaching a Tasco red-dot pistol sight to the side of the camera. Once the sight was aligned with the camera, following a rocket in flight was easy with the 1x red-dot scope. Keep the dot on or near the target object, and you can be confident the object will be near the center of the video frame.

Doing the same with a keychain hat-cam is a little different. A pistol scope is a bit too large and awkward to use with the keychain camera. Even the tubeless type (see last photo below) obstructs your view considerably. But the concept is fairly simple. Focus a bright LED down to a small dot and aim it at a clear reflector that will reflect a portion of the light into your eye. And the apparatus has to be adjustable so you can align it with the camera. Ideally, some optics would allow for collimating the beam of light so it would make the smallest possible dot that appears focused at infinity. A laser would be great for this, but it would not be healthy for your eyes.

Here is my first attempt at a red-...Continue Reading