Building a RC pilot kite

So I can’t be bothered pulling the lift kite around every time I want to land…
Has anyone taken the next step in automating a single line lift kite with
http://ardupilot.org/planner2/


I managed simple steering by remote about 5 years ago… I want to try again with the fancy new controllers. Is this what KiteSwarms runs on?

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I oftentimes wish the day had a bit more than 24 h so I could fit in cool stuff like a RC kite. I may get around to building this at one point, because its a super useful tool for many things. My current work on the matter (which was also a Yak shave to begin with) has stalled recently unfortunately.

I can easily see the benefit for your project (@Rodread) in having a steerable pilot kite (steerable power and orientation). I think many others would be able to use it as well. Some uses:

  • measuring windspeeds at many altitudes
  • a pilot kite/lifter that may be taken easily down and depowered
  • support for launch operations
  • failsafe tether for other AWE (eg for preventing crashes to the ground of another AWE system)

Perhaps one of the lowest hanging fruits to promote AWE right now would be to create the steerable kite and make it available affordably to the community (hopefully open source kind of affordable, but even better if it may also be purchased directly in ready-to-fly condition)

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I also need that for high altitude testing. I start to work on that. Not as easy as it seems. You need something that can reel in 25 kg continuous pull for a 4 m2 pilot. At least. You also need something irreversible otherwise you will reel out. You need a battery, a controller. As the motor has to be powerful , you need a brushless, low rpm, or a motoreductor at least. You have to do foc control with your brushless, thus you need an esc. You also want it to be lightweight. And the list is not exhaustive… All that makes it not that easy. I post a quick cad on a fb kite group to see if people would be interested for this at 300 euros. Result was mitigates…

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This post is a bit more about a desireable lifter controller … not so much experience…

The speed and accuracy of telemetry from modern autopilots is amazing.
I doubt we need an AoA control if we have a good steering control. AoA control will be good for optimising line angle to reduce cosine losses.
If you start with a well-balanced lift kite …You won’t need 25kg pull for steering line control.
In the video in the post above Can you share your experience with your lifters?
I only used one model yacht servo (servos are a bit power hungry) with a dual pulley horn on top.
One pulley wound clockwise, the other anticlockwise. When both turn together 1 reels in the other out.

Airborne, all I need is a bit of power (like kitesat / kiwee), a controller, a servo, a wee battery, bms and esc with comms. (maybe a line tension sensor but gps and altitude are basically built in)
Getting the data into the ground gen control will be the most important bit for me.
As this will let me control the rotors to reduce ground impact
If I can also instruct the lift kite what to do… Bonus.

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On a lifter kite you don’t have any control line. So If you want to reel in reel out a pilot for example, or a Cody or whatever single line kite you wil 'eed that 25kg pull at least. What you described rod is a modified lifter. Not the basic setting.

Supplying my sketch of a lightweight, batteryless, no weight below the skin, depowerable, steerable RC pilot kite.

The red stuff is a controller/wiring.

Function: when the kite starts to fly, the «windmills» at either wingtip start rotating. This powers the controller mid center (with the help of a rectifier circuit and a capacitor). The controller will first stabilize the attitude of the kite by adding a breaking force at either wingtip. It controls towards zenith with a gyro and accellerometer sensor. For depower, a breaking force is applied to either wingtip. Ideally the kite has a positive \frac{\delta C_m}{\delta \alpha} to make it stable in pitch and then hang the bridle on pulleys for a wide range of \alpha with little input.

Mayde a inflatable leading edge would benefit such a kite to make handling of the propellers easier.

In terms of actuators, you only need to set up a voltage over the terminals of the windmills dynamo to control the breaking force, along with a resistor to soak up excess energy. For most simplicity, just use a two wire brushed motor.

This would be a simpler design rather than a control pod with servos acting as winches on the lines. You are getting rid of:

  • battery
  • swinging weight below the kite
  • power harvesting (in addition to the actuators)
  • sensors for actuators position

I could potentially tap a little power from the top of my stack of rotors, then send the power up to the lifter control.
The modification needed to add a bit of steering really doesn’t require much power.
I’m also expecting to still be able to actively reel the lifter from ground as needed.

The kite I drew could be a node in a kite network and figure out itself how and when to depower your stack locally

A kill switch could be implemented by yanking «SOS» on the tether to get rid of the radio as well.

Or just have additional bridles. The controller unit handles some of them. The main load is transmitted over the others.
The controller could handle depowering lines on each side.

The reason i like the windmills is the simplicity of the actuator and reading back force and windspeed (adjust load by switching a resistor, while measuring only the voltage and current). I also like that the system has no battery and just works when subjected to wind. If the controller does not boot, the kite will be depowered…

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Sounds great. I don’t get the depowering part. Not sure it will have the effect you described . I think you will maybe have some issues with starting your propeller. Also probable voltage regulation issue :like exploding capacitor for example.

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The kite is depowered when both windmills are breaking a lot. If the kite is a C kite and front/rear lines are connected via a pulley, and the kite is perfectly balanced, then adding a downwind force will cause the kite to depower/reduce \alpha. This is because the downwind force is at the wingtips at a point lower than center of gravity. Its all about tuning the moments on the kite to make it balanced, like for an airplane

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Not sure you can control propeller drag that way. I won’t be categoric because I never measured that parameter but from my experience, it seems to me that drag is not greatly affected by the amount of power you extract from the propeller.

I wonder if some elements of this single line RC Stunt Kite (video below) could be used.

Tethering this paramotor might be interesting…


A few adaptations…
take the wheels off, bridle it by the wheel mounts…
Maybe turn it to have the fan into the wind with turbine blades for keeping charged
Add an IMU / ardupilot…

Designed for a very light load. Probably so many changes to be made, that you might as well start from scratch.

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