09 August 2012

Balloon-borne camera, part 8: switching to kites and fixing poor choices

Like I told you last time, we had to make a sad decision and give up on the balloons in favor of kites. This exposed some bad practices I described in earlier posts, which will be corrected as soon as I post the corresponding correct practices!

So it was with sadness in our hearts but determination in our eyes that we went and bought our first kite, from a nearby hardware store (yeah, a hardware store). In fact, it was this kite, and it was super inexpensive. I was a little apprehensive about how much weight this little kite could lift, given our previous troubles with the balloons, but man was I proven wrong. With a little help from the high winds of an oncoming storm (note: it is a pretty dumb idea to fly a kite in a storm), we got our camera way up on the first try! No pictures, sadly, but if you look at pictures from previous posts and replace the balloons with a small Canadian flag kite, you'll get the idea.

So it worked really well, except (there's always an except)...
the line kept snapping! Good thing we didn't actually have our camera loaded into the rig. What the heck was going on? At first I suspected the cheap kite line that came with the kite - cotton so thin it looked like dental floss - but after the second or third time the line snapped I realized the breaks were always happening at the points in the line where I had tied knots to attach the picavet.
If you look through the websites of different kite aerial photographers, you'll notice that they always use some kind of clip to attach the camera rig to the kite. I wondered why nobody tied knots in the line like I'd been doing, and I figured it was because they prefer to attach the camera *after* the kite is in the air. Hey, it's just a matter of preference, right?

Nope. Turns out that knots are a weak point in a line, and when you get the kind of forces a kite generates it can make the line break pretty easily. It ALSO turns out that it can take a few tries to get a successful launch, so you don't want to haul your expensive camera up on the kite until the kite is flying steadily and not going to take a nose dive into the ground. This happened quite a few times. I guess I didn't fly enough kites as a kid.

Fortunately a quick solution wasn't too hard to come by. For about $2.50 each, you can pick up a keychain carabiner from the checkout line in a grocery/hardware/convenience store. Once you have the kite up and flying steadily, wrap the line around the carabiner a few times, like shown:

The line is wrapped 4-5 times around the carabiner. Note: careful with the line! If the kite is pulling hard the line can get quite sharp, so you might want to wear a pair of gardening gloves for this. Also, it helps to have another person with you to help out

Do this again with the second carabiner, about a foot further down the line.

Both carabiners, with a pen for scale. The separation is definitely something you can play with. The carabiners are different is because I lost one in the grass and had to replace it. There's a lesson in there to keep track of your stuff!

When the line goes taut again, it will keep the carabiners in place quite securely! You can clip your camera rig into these carabiners just like we were clipping it into the loops in the kite line earlier, but without risking snapping your line. Congratulations, you have avoided a significant amount of frustration and confusion!

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