Doing KAP With A Drone
by Gregg K.
Q: Here is a question and a type of idea I've been thinking about for a while.
I have a few small drones with cameras. Some are smaller than others.
With all the issues with people upset about drones and a few people doing stupid things with them there is a lot of push for rules and regulations governing drones in the USA and in other countries as well.
We have federal aviation administration rules but also other rules regarding drone flying in this country but it's even worse in some countries now like Canada.
Additionally park regulations for national parks in this country don't allow drone flying due to some accidents and if you try to get permission usually you can't and may get a huge fine.
I noticed that some people do kite photography with small cameras on some kind of string harness to take still photographs using kites. Which seems kind of cool and has to be a little bit rare.
Well my thought is there is a small drone which weighs a bit but it's not super heavy it weighs about as much as a 3DR Solo gimbal and GoPro hero camera or perhaps three or four times the weight of a GoPro camera.
I'd have to look up the specs or weigh it to get the exact weight. But it's a Parrot bebop 1 drone.
Now this drone has a build in camera that can take stills or video. But it uses digital stabilization and uses a 4K sensor on its side with a fisheye to be able to look up or down and left or right s little bit with digital movement of the camera cropped to full had resolution. What makes this drone amazing is the digital image stabilization can be set for both axis vertical and horizontal and that means even if you twist or turn the drone on a roll axis the image stays level.
It also broadcasts back the video to the ground and records it.
Now this drone is illegal to fly on national parks and some wildlife areas I suppose the reason could be it's motors and small props might make enough noise to bother wildlife but also the whirring sound of the motors might bother people. The regulations say we can't have a remote self powered drone but I think kites are allowed. So my thought is if I could just strap the drone to the bottom of a kit or harness it to a kite the kite could lift it up and I'd have stability and record the video from up high in a legal manner.
My question is what kind of kite should I build to lift a drone that is about one point up and give some stable flight but extreme stability isn't needed. My second question would be is there a way to have the drone or kite be rescued in other words some way to turn the kite into a kind of parachute in the event the line snaps.
I don't know if there is a technique where a drone and kite could be recovered if the tension is lost on the string from a string snapping or if I should think about some other way to activate a recovery.
It seems a cargo kite for drones in national parks and other areas would be a nice thing to own.
I haven't thought too much about this yet. But my basic idea would be to send up the thing without props but the drone would be powered up just for live feed and to run the cameras.
The only slight downside to this is the bottom metal frame for the bebop will get hot as it's a heat sink for the small computers which are running its software. That would mean I'd want to attach it by the quadcopters prop arms and not have heat get into the kite or the fasteners.
Also some have speculated that a crashed drone with a battery might cause a fire and that could be one of the concerns for national park restrictions. That being the case I'd need to design a kite that is fairly safe even with a crash to prevent too much jarring of the drone on impact.
I have no idea how much line or what strength I'd need for a one point payload and how I might design this to fly in light or heavy winds. It's probably better if it can fly in light winds and be brought down safely if the winds pick up.
Just some thoughts.
A: I'll quote some excerpts from your submission as I go...
"We have federal aviation administration rules but also other rules regarding drone flying in this country but it's even worse in some countries now like Canada."
Rules, rules, rules. I can see you don't like them with respect to engaging in a hobby. The blanket 400 ft height limit annoys me a bit over here in Oz!
"I noticed that some people do kite photography with small cameras ... "
They certainly do. And have been since the late 1800's! Although not surprisingly the cameras were a lot larger back then. You can check out my own efforts here... KAP using big dowel-and-plastic kites.
"My question is what kind of kite should I build to lift a drone that is about one point up and give some stable flight but extreme stability isn't needed."
According to some specs I looked up online, your drone weighs 400g. With a simple cradle attached to the flying line as per KAP (Kite Aerial Photography) practice, it's roughly double the total KAP rig weight that I use with my large dowel kites. However, my 2.4m (8ft) tall Multi-Dowel Sled design is a strong puller and hardly feels that weight in most Light to Gentle wind conditions. That is, 6 to 19 kph or 4 to 12 mph breezes.
In Moderate winds, the huge Multi-Dowel Sled begins to become unmanageable, generating line tensions around 20 kg. So then it's a good idea to switch to a smaller kite. Hey, I just happen to have designed the Fresh Wind Sled also ;-) Based on the Multi-Dowel design, this kite is just as easy to make and operate but suits Moderate to Fresh winds. That is, 20 to 38 kph or 13 to 24 mph. At those wind speeds, the Fresh Wind Sled will also provide ample line tension for carrying the weight of the drone.
"My second question would be is there a way to have the drone or kit be rescued in other words some way to turn the kite into a kind of parachute in the event the line snaps."
A tougher one to answer to your satisfaction probably. (Of course, with a KAP rig dangling from the line, below the kite, this question is irrelevant if the line snaps between the KAP rig and the kite. Unfortunately, that is the most likely place for a failure!)
Firstly, by using a flying line of ample strength and making sensible decisions about when not to fly, the possibility of a line break is fairly remote. I fly both the Sleds on 200 pound braided Dacron line.
Secondly, very accurate wind meters are affordable and compact. Getting one of those would take the guess-work out of evaluating conditions. Alternatively, using a set of spring-scales would allow you to take direct readings of line tension. Again, taking the guess-work out of it. Do some experimentation, set your safety limits and stick to them.
How's this for protecting the drone - surround it with a bamboo cage that would absorb most of the impact if the rig fell from a couple of hundred feet up. My home-made rig is actually made from 4 bamboo BBQ skewers (plus some paddle pop sticks!) and provides a measure of protection for the camera. Earlier, I had used a tetrahedral rig which would have been even safer in the event of a free-fall. I only stopped using it because it was less convenient to insert the camera before a flight. So - consider a nice big light-weight bamboo tetrahedron with the drone slung inside somehow.
"The only slight downside to this is the bottom metal frame for the bebop will get hot as it's a heat sink for the small computers"
In flight, there will be no problem as the drone will be hanging in air. As you suggested, attachment to the rig could be via the propellor arms, thus avoiding the hot underside. There's another advantage to using a big cage - after an unintended landing due to a sudden drop in wind, there would be far less chance of starting a fire since the drone would be undamaged and clear of the ground. By the way, such an unintended landing would usually be quite soft. However, the rig could get dragged about a little, over the ground.
"I have no idea how much line or what strength I'd need for a one point payload"
A self-leveling rig is suspended from the flying line at 2 points. You need to look up and learn a bit about Picavet KAP rigs. I use 20 pound line through heavy paper-clips for minimal friction in my Half-Picavet setup. You might need 50 pound line - and proper pulleys! Don't forget that it's more than just the rig weight that the line has to carry. Rough air can bounce the rig around a bit at times, as the line goes taut suddenly.
"It's probably better if it can fly in light winds and be brought down safely if the winds pick up."
I've already mentioned 2 kite designs to cover a wide range of wind speeds. Here's a tip for bringing down a hard-pulling kite with minimal effort... Use a metal carabiner, like rock climbers use. I don't even attach a strap or anything to it. It's a matter of preference. You simply clip on the carabiner while the flying line is firmly anchored somewhere such as a tree trunk or sturdy railing. Then it's a simple matter to slowly walk out towards the kite, slipping the carabiner along the line. The KAP rig will come down first of course, so you can just leave it there on the ground while you continue out to the kite. With the kite down and rolled up you can return to detach the KAP rig.
The e-book 'Making Dowel Kites' has detailed plans for making both the Multi-Dowel Sled and the Fresh Wind Sled.
Note that these Sled designs are very simple to make and the classic 3-spar design has proved very stable and reliable in flight. The Fresh Wind Sled does need it's drogues though, being a more sturdy kite with more inertia.
Hope all this proves useful!