Wednesday, March 30, 2011


 Sunday I took the plane out flying and had it taking pictures of a residential area in autopilot mode.  It is now flying itself but is "snaking" back and forth between waypoints, like it is over correcting for the turns.  After a few flights the battery died and in gliding it in for a landing I crashed it, hard.  The photos tell it all.  I glued it back together and it should be just fine now but it was one of those "well that's not good" moments.

This morning I ordered the FPV camera, tx/rx.  It is a RangeVideo 1.3ghz 800mW transmitter with a V antenna, a color camera with night mode, mic and multi channel receiver with 3db whip antenna.

Don't worry, I fixed it. lol

Tuesday, March 22, 2011

Everythings Working Now.

After loading the 2.01 firmware everything that I was having trouble with works, telemetry, loading flight plans, sending commands/waypoints via mavlink, and most importantly Auto and RTL modes!  I do not know what the problems were but they seem to be fixed.   RTL altitude is too low when set in HK GCS so I just need to work with that program a little to get things figured out.  The video was taken in manual mode.

Still not there

Todays test flight led to a crash course on instrument flying.
I was running APM 2.0 beta and RTL was not working right.  The plane would make it back to the start location but by way of an almost .5 km detour.  I would be flying it then select RTL and the plane would start circling (climbing) then once it got to several hundred feet it would head away from the start location and slowly make its way back around, not the quick turnaround and direct path back as would be expected.
At one point it flew behind some trees and was completely out of sight for several tense minutes. All I could do was watch the heading and altitude on my laptop.  By leaving it in RTL it maintained altitude and I piloted it back into view just by the model on the GCS map.

Tonight I manually uploaded the 2.01 Beta and will test it tomorrow.  I was getting lots of 'port in use" errors while uploading flight paths earlier today and have not had any of those with the update so things are looking up again.
Also I got 3 more Zippy Flightmax 2200mah LiPos in the mail today- they are currently charging :)
Now I'm just waiting on my high capacity transmitter battery to replace the 600mah one that came with it from Futaba.
next upgrade will be a current sensor to monitor battery voltage and remaining power.

Saturday, March 19, 2011

Creamers Field Flight

 Today I finally figured it out.  The EasyStar is a 3 channel plane, meaning that it has no ailerons.  Because of this the rudder acts as the ailerons, turning and banking the plane.  Since the rudder creates the same movement as the ailerons it is common to put the rudder on the aileron channel to make flying it easier and more like 4+ channel planes.  I had done this by plugging in the aileron channel (channel 1) into the rudder input on the APM board.  This made it fly great in manual mode (as well as in the HIL simulator because that plane had ailerons).  The rudder servo was plugged into the rudder channel on the APM (kinda common sense, i guess...), what I didn't figure out was that the APM program relies on the ailerons, not the rudder, to control most of the movement of the plane.  I had gotten the plane to fly somewhat straight in auto modes twice before but could not duplicate the results.  This was because when I selected the auto mode the plane happened to be flying in the right direction and decided it only needed rudder to correct its course.  When it was not pointing in the right direction it would try to fly the plane with only the rudder (thinking it had ailerons) and go into the high speed circle mentioned earlier.
I changed the wiring by putting the rudder servo on the aileron output of the APM board, reset it, reprogrammed it and uploaded a flight plan.  When I got to creamers field I got it all set up and sent it up, flew it quite aways off, set it to RTL and to my excitement it slowly turned around and returned, then circled above.  After uploading a new flight plan I got it to fly its course.  So I brought it back, attached the camera and uploaded another plan and took these photos.

Dad and I next to my truck

Creamers Field barn

Tree I almost hit

Clay's old house

Residential area of Fairbanks

I did have a close call and it is not at 100% but today was a big improvement over the circles.  When flying over the barn the plane stared to loose altitude and came very close to a tree.  It was so far away I could hardly see it and luckily RTL brought it back.  I did crash on landing breaking the camera "skid plate" and tarnishing the otherwise great flight, but that was my fault.
I also think that it's descent was because I didn't check all the altitudes or there was a conflict in the route that caused  it to dive, either way it can be fixed with better flight plans.
I will also be much more comfortable when the plane has its FPV (first person video- live camera that transmits to the ground giving you a point of view from the "cockpit" of the plane) camera so I can really see where it is going.

Friday, March 18, 2011

Photo Flight

Today I took it for another flight in a field across the Steese from my house.  After reloading and updating to the 2.0 beta firmware the plane still is flying in circles.  I really do not know what is causing it because it works fine in the HIL (hardware in loop simulator), and I'm beginning to wonder if this is a hardware issue. Besides that the plane took some great photos today.  The house and yard in the pictures IS NOT OUR HOUSE! lol

Dad and I next to the bug

Steese Expressway

Thursday, March 17, 2011

A Note About LiPo's

Lithium Polymer batteries or LiPo provide much more energy per unit of weight than other types of batteries, making it the best choice for electric planes.  Their only downfall is they are very sensitive and if not charged properly can actually explode causing fires in homes and cars.  In recent years they have gotten much better and safer but still require care for use.  If charged too fast or overcharged, the cells will balloon and heat up.  Each cell has to be charged evenly using a balanced charger that monitors the voltage in each cell.  They can also be damaged if the voltage drops below 3 volts per cell.
Today after a fairly long flight I took the plane in and was working on it and left everything plugged in.  The Electronic Speed Controller (ESC) has an auto shut off that will turn the motor off before the voltage drops too low while leaving the rest of the plane on so you can still control it if your battery dies mid flight.  After a few hours with the battery plugged in, I came back to find the Xbee was off and the lights on the APM board were dim.  When I checked the LiPo it was warm and had already started bulging.  I pulled it out and checked the voltage with a multimeter and found the 3 cell battery (that should not be below 9 volts) was at 3 volts.  I threw it out and counted it as a cheap lesson learned about LiPos.

Xbees and Aerial Photography Camera

Today I received and installed two new Xbee wireless modems for telemetry.  It required some soldering to the APM board and new firmware for both Xbees but I got it to where it sends data to the ground station program on my laptop.  This shows an instrument panel with all kinds of data like location, speed, alt., heading, and artificial horizon.  It also displays what mode you are in, GPS lock and number of satellites the GPS is connected to.  I dont have it figured out yet but I can supposedly send flight plans and commands to the plane wirelessly.

I also mounted a servo to a Fujifilm X10 7MP digital camera.  I will put the camera in continuous shooting mode and the servo which is activated by a switch on the radio, will press the shutter button and take pictures for as long as the switch is flipped.  The camera only points straight down for right now, and is attached to the belly of the plane (directly under the CG point).  To protect the camera on landings I built a lexan (Plexiglas) cover that acts as a skid plate. 

In the first test flight I accidentally shut the camera off before launching the plane, reverting it to normal shooting mode when it restarted.  When I landed the plane it had only taken one picture and its battery was low so I couldn't send it up again, otherwise it worked.  To prevent the shut off from happening again I set a piece of Velcro on the camera slider so it will be locked open.  I changed the endpoints on the servo in the Futaba 7C settings so that it only moves far enough to press the shutter button.  From what I have read, some high toque servos will break the shutter button if they go too far.

Xbee on the plane (with white antenna) and the second Xbee with its high gain antenna mounted on the lid of the laptop.  Camera is underneath the plane.

Close up of the servo on the camera,  I also glued a plug into the side of the plane so the servo has a quick disconnect and can be added or removed easily.  The whole camera/cover assembly is attached with Velcro.

First picture from the air

Wednesday, March 16, 2011


After adjusting the dip switches (channel reversing on the APM board) I got it to respond in Stabilize mode.  Now when holding it if you pitch it any direction the control surfaces move to return in to level flight.  It performed well in its test flight but autopilot still isn't working along with Return To Launch mode.  I have been doing lots of research on the forum but have not found anything. When switched into either of these modes the plane banks hard right, goes full throttle and stays in a fast, tight circle.

Monday, March 14, 2011

HIL- Hardware In Loop simulator

The APM board can be programmed with a HIL (hardware in loop) version of the regular firmware that enables it to send and receive data from Xplane flight simulator.  This is how the autopilot is tested and goes like this:

APM 2.0 beta HIL is loaded onto the APM board
APM is connected to a computer via USB and the receiver is powered with a battery
Software is used to connect the APM to Xplane so they can send data to each other
Xplane sends all the location data to the APM board, basically replacing all the sensors including the GPS.
the APM process this data and instead of sending it to the servos, feeds it back to Xplane to move the plane in the Sim.  The plane is fully controllable with the RC controller because the APM processes the RC inputs too!  This makes it act like an RC flight simulator like RealFlight.

I did have some issues with the channels being reversed (again) and at first the plane would fly upside down in the auto modes.  At first I fixed this by reversing the channels on the interface software and just dealing with inverted controls on the 7C controller. Now I have a new model stored in the 7C just for the simulator with the correct control configuration.  Now whenever I fly in the HIL I do not have to manually reverse these channels, I can just select the model for simulator.

Friday, March 11, 2011

First Flight

Today was the first flight of the UAV.  I learned that during your pre-flight inspection you have to check control surface function and direction.  If you don't (especially on the elevator) your plane will go down when you tell it to go up, and it will crash.  After reversing the channel on the radio it flies fine in manual mode but acts erratically in any of the autopilot modes.  The plane itself is very maneuverable and fast, but also can glide for a long way.  It also does loops (inside and out) and can fly upside down.

Wednesday, March 9, 2011


The batteries are in and everything is hooked up and working so its time for gluing. Before that I milled some  foam out of the fuselage so the battery could get closer to the center of gravity.  Once everything was together and set, my dad and I put the servos and servo wire tubes into the fuselage.  After I reversed some channels on the 7C it is ready for flight.  The APM has several different modes that it can fly in: Manual, Stabilize, Loiter, Return To Launch (RTL) and Auto are the ones I will be using but it also has two Fly By Wire modes as well.  Because I want to use more than three modes (limited by the 3 position switch on the radio) and mixing switches is not possible on the 7C, I opted to put them on the flap knob.  To index the modes on the knob I set a piece of paper on it and noted where the modes changed, then I took a picture and drew it scale in AutoCAD.  Now I can accurately select my five modes ( of six possible). 
Had a problem with one servo though. When I glued it, the glue went into the servo through a small crack and stuck two gear together.  After taking the servo apart I was relieved to find that the lubricant on the gears prevented it from bonding to the gears themselves.  After cleaning the glue off the servo now works fine.


Wednesday, March 2, 2011

Multiplex EasyStar

I got the Multiplex EasyStar in today.  It came in a very large box that had all the parts and some extras that I ordered.  The plane is made of ELAPOR foam and has a 54" wingspan.  The upgraded brushless motor I ordered for it should add the needed power to lift the plane and its payload.  The 2200mah LiPo batteries that should be here in a few days will give it longer flight time over regular NiCad batteries.  I am waiting on these batters to get here so I can test everything before I glue the two halves of the plane together.  I did glue the tail section together and it is ready to be installed as soon as the rest of the plane is together.