ADSB - Part 2 or I now have a public server to display locations on

As you might have seen in a previous post I have been working an ADSB receiver for my UAV.

Well now I have also created a server with the web front end running on it at http://globelock.dyndns.org:8081/

I still find it amazing how far away I can pick up aircraft from the standard antenna sitting on my roof

Kitting out the airframe

I have started to kit out the airframe.

This is the 4s lipo (center battery) for the APM

Also there are 2 x 3s lipo (rebuilt from old laptop batteries) that are for the flight computers.

The main APM battery lasts for around 5 hours so I am also building a battery change over to switch to a backup battery if it runs low. I would like to achieve a total flight time of around 10 hours

    

Sending bi-directional data from serial port across UDP

One small issue on the glider.
How do I send data between the APM and the ground station economically.
I originally was using a TCP connection (ser2net) but was having issues with packet loss and connection drop outs. This  was a problem as each time I would have to reconnect and initialise the link. Not a good thing whilst flying.

So after a bit of research I have moved over to socat. One command and the link is up :)

scocat UDP-LISTEN:5761 /dev/ttyACM0,raw

So what does this do, it sets up a UDP server on port 5761 that is connected to the serial port ttyACM0.
This allows the ground control software to talk to the APM directly and if packets are drop,missing or wrong order they are ignored.
If this was TCP then each of these errors would cause a resend for the point at which the error occurred

Autopilot has arrived

In record time the APM arrived today.

Now coming to grips with qgroundcontrol as MissionPlanner requires Windows which I dont have.

Next to connect it up to both the plane and the raspberrypi

 

The APM is in the middle, compass/gps on the left and the battery voltage/current sensor at the bottom.

Auto Pilot ordered

I finally order a Auto Pilot for the glider.
I found that there was a $40 discount until the end of next week. That more then makes up for the low $AU

Now to start on an AuduPilot Glider version

Back to software

So what do you do with a week and no work?

I got back to software for the visual recognition systems.

1. Fork off a few projects on github
2. Develop and test some changes to make files and sundry scripts
3. Push back to github
4. Merge request back upstream

This is simple :)

why do some people want to do things the hard way and think that merge requests are so hard.
Oh well they can stay in the dark ages....

The start of the avionics and vison computer systems

So it started out as balancing the plane. Testing showed that it required around 1.2Kg of weight in the front of the wings to get it nearly correct. Initially I had a single 12v Gel cell that was about right but latter found that due to its age it was failing under load. The solution was to get a pair of 12v 2A/h seal lead acid batteries. these cam in just under the required wight. 

That is ok as I need to setup a pair of switch mode PSU's. one for the servo control system and one for the on board computers driving the SSD and cameras. Initial static test are ok.

Soon the body will be done and the basic avionics will be in place for test flights.

Wing joint connections

It turns out that having stability in the wing joints is hard and whats harder is to thread the servo control cables through the wings.

So to this end I have put in perminate wiring .

The socket is a 8pin din plug through which I run the 2 servos and a usb connection for the on-board camera in the wing.

 

Then when I go to connect the wing up all there is a plug to plug in, the carbon fiber rod (at rear) to lock in and then screw up the top and bottom plates in the middle. Ready to fly. 

Now the balancing act

So here we are about a year down the track and I have learned a lot.
First thing is that all dxf files are not the same. What I found was that when I selected sections from the cad drawing to be cut and exported from draftsight to dxf files that some of the shapes came out wrong. Curves were the main issue. They would be moved and rotated to odd locations. This means that I then needed to go in and edit them as dxf format for the cam software to pick them up.
This then showed that not all splines joined up and the cam software would not sort correctly. There were also cases of the same spline being repeated so that the cutter would do multiple traces of the same path.
Lasers are brilliant for cutting balsa wood but multiple passes just char to much. You can get away with a dvd laser if all you want is a mark but a 3w is better and a 10w would be excellent.
It is surprising how much weight you need to balance the glider. It's just over a kilo in my case.

Air brake woes

Whist finishing of the plane i have run into some problems with the air brakes.. They just do not close fully

So I went out to one for the local model air field to see some of the glider pilots and talk over some these issues.
Whilst there I found that the NFR (Nearly Flight Ready) model kits for gliders also were using brakes and that one of the few jobs that you do is to re-enforce the brake.
So my example is the shaping of some 6mm sq spruce spares to glue to the inside as in the following picture.

 

So now with this re-enforcing they close fully.

I also found out some more interesting information on the controls. The air brakes are normally connected to the throttle control and are therefore proportional in control.

Also my total aileron control length it about 50% of the wing width and on the NFR models its more like 25%. I wonder what that will do the flight control, might be very twitchy.

Nearly there

Only got the canopy left for the build

Wing is covered

The left wing is now finished and I am just finishing off the center wing so that I can cover it.
Should hopefully be done on the other end by the end of next week.

Wing tips

After laminating several peices of balsa and spruce together I created the following wing tips.
The former that I used was a roll of solder.

The central wing

Just a few more pics of the central wing of my glider

The plane, the plane. Master the plane

Recently I upgraded my mill to use a new 1W 808nm laser diode from that
which was removed from a DVD laser burner and I must say its great to
now be marking out my wooden templates for my scale glider at 200mm/min.
The old one just didn't cut it (no pun intended) as it could just barely
make it to 40mm/min.

Marking out now looks like

The problem here is that there were small gaps in the CAD DXF file and
so the laser stopped and burnt holes :(

Once that was sorted I continued and now have the central wing done, all
800mm, and have the remaining 3.2m to go.

I have also done the body frame and feel that I can now do wicker work
as well