Internet Weather Links

  Weather is kind of important for a solar RC airplane.   We don't want rain, or too much cloud, or too much wind.   So we will collect some links here, trying to move the best toward the top, for checking weather near us.   WindGuru Aguilla Seafeathers Bay - Can see how much cloud, rain prediction, wind speed and direction. East Anguilla - map showing wind at different date, time, altitude  Caribbean Radar Composite - Radar from all around the Caribbean.  Can see where it is really raining right now.  ANIMATION SATELLITE et RADAR de METEO FRANCE - Radar from satellites Tropical Weather, Hurricane Watches - major storms                

Switching from iNav to Ardupilot for Flight Controller

   We had been using iNav software for the flight controller but have decided to switch to Ardupilot the following reasons:    1) Ardupilot can have a "companion processor" like the Jetson Nano that does vision/AI and decides things like which way to go.   We really want to explore what can be done with AI on a solar powered airplane.   Like can it avoid clouds and stay in the sun more, can it scan the horizon with a telephoto camera looking for boats, can it head for a boat automatically, etc.   This seems fun.    2) Ardupilot can use a companion processor to communicate over cell data network (4G) to a ground station.  With this we could fly all around Anguilla and still have communication between the ground station and the airplane.  So from the ground we can change the mission plan during the flight.    We could decide to go to a particular boat, or decide to come home because the change of rain has gone up.   Or if we don't have AI avoiding clouds we could do it

Copper Clad Aluminum Wire

  Aluminum wire is 61% as conductive a copper and only 30% of the weight .   So for the same amount of conductance it is half the weight.   Since weight is an important thing on a solar airplane, this is interesting.  The first problem is that the layer of oxide on aluminum makes it very hard to solder to.   We need to connect wires together, so this is a problem. There are copper clad aluminum wires .   The core is aluminum but the outside is copper.   This way you get most of the light weight of aluminum but you can still solder to it like copper.   Below is a picture: A bundle of thin strands seem to have a bad reputation for corroding if outdoors.  I am hopeful that a single solid core, about 1.5 mm diameter, would last well enough for me.  However, I am can't find this on Amazon so far. There is a place in China that might work .   There is a useful website for calculating power loss in a wire depending on type, thickness, length, and load on wire.  And another similar online

SN1 - First custom plane

We are working on a clean sheet wing design that has perfect places for 8 solar panels, Jetson nano, DJI Air Unit, supercapacitor, motors, servos, wires, etc.  But the CAD software for this is at the office and in our current Covid situation working on solar airplanes is "non essential", so not a good enough reason to leave the house.   Also leaving your house to fly RC airplanes has been against the law for the last 3 weeks, as I understand it.   We have planned to eventually make a VTOL plane.  Since such a plane could fry from our house, even during lockdowns, this seems like a higher priority now. Also, we have the "test wing" that we made just to see if the idea of CNC cutting a frame out of foam and covering it was reasonable.  We can probably make get this to fly and learn something, since it is at home and we can play with it.   This can be a step toward our VTOL plane. The first step was to use a hacksaw to cut out a bit from each leading corner so we could

Cloud Dodging in the Caribbean

  Caribbean clouds are often only covering part of the sky.   If there was 30% cover and we flew our plane around randomly we would have much reduced solar 30% of the time.   But if we planned our route to optimize solar power, we could do much better than that.   At first we could do this manually but eventually we would like AI to deal with this automatically.        With a Jetson Nano we have plenty of power to work on this problem. If we had it tracking clouds objects (number for each cloud) as we moved to the side we could see how much the angle changed for each of the clouds and figure out how far away they are.   This type of depth perception is called depth from motion .   I think this won't be too hard really.   Some papers related to this topic 1)  Cloud Detection System for UAV Sense and Avoid: Cloud Distance Estimation using Triangulation     $33 US for non-members   Abstract: Sense and Avoid is gaining importance in the integration of unmanned aerial vehicles (UAVs)

Motor Mount in Foamular 250

 The Foamular 250 we are using is rated for compression of up to 25 psi (lbs/sq-inch).   It is more stiff than other foam I have seen in model airplanes and a bit heavier.   We cut out the foam where we don't need the strength, so we are not hurt by the weight.   For motor mounts it seems like this extra strength could let us just gorilla glue some screws into the foam.   We tried this and it seems to work fine.  For this experiment we used M2x20 screws.  So 2 mm diameter and 20 mm long.  The motor mount uses 4 screws but for this test we only used 2.   We drilled two holes in the foam and filled them with water (poking small nail in to get all the air out).   Then we covered the screws with gorilla glue and put them in.  First we tried just putting a weight on to hold them in: But it was hard to get it to hold both screws down well.   So we put a piece of plastic over and a clamp and let it cure overnight. So for the test this is what it looked like: And here is the video of the t

Stabilized Camera / Pan-Tilt

  With a "two servo micro gimbal" you can tell iNav to stabilize your camera.  The flight controller already has tilt sensors and a computer, so with the iNav software setup right it can control the servos and stabilize a camera.  You do need to have 2 extra servo outputs on the flight controller.     There are a number of these on Amazon.   If we just search Amazon for "servo gimbal Mini Pan-Tilt mount FPV" there are several for under $25 but you may have to put in your own servos.        You can also 3D print the plastic parts and add your own servos.   This is for a Raspberry Pi or Jetson Nano type camera but should not be hard to get it to hold a DJI Camera. There are also head trackers so that the airplane can point the camera where you turn your head.  This increases the feeling of being on the airplane, so can increase the fun.