All posts by Json

Enabling RSSI or Link Quality in MinimOSD with EzUHF Rx and HKPilot32(or Pixhawk)

This is a quick how-to to get the RSSI or LINK quality on your MinimOSD you need the following:

1)  Download MinimOSD Tools and Firmware. Download the MinimOSD configuration tool (CT Tools) and Minimosd ‘extra’ firmware from: https://code.google.com/p/minimosd-extra/

For my setup I download the following files from: https://code.google.com/p/minimosd-extra/downloads/list

CTTools:   CT Tool for MinimOSD Extra 2.3.2.0 Pre Release r727.zip
Firmware: MinimOSD-Extra_Plane_Pre-release_2.4_r719.hex

2) Setup EzUHF Receiver to send RSSI or LINK quality values.  Since you are using a Pixhawk or HKPilot, the setup should be that all the channels goes through channel 1 which is ‘muxed’.  Connect to your EzUHF receiver using a USB cable and open the ImmersionRC Configuration Tool.  Once connected, just set channel 8 to either RSSI or LINK  (only channel 8 will with MinimOSD for now so its pointless experimenting with other channels).  You can use either RSSI or LINK, but I suggest you use LINK as RSSI is all about the signal strength and not the actual quality of the link.  Upload the settings to the receiver.  Here’s how it looks like:

ezhuf rssi setup
ezhuf rssi setup

4)  Do not edit any parameters in APM or MP.  You do not need to change or update any settings in the AP configuration so leave it as is.

5)  Get the maximum and minimum RSSI or LINK PWM values in MinimOSD.  For this next step, both segments of the MinimOSD must be powered or any updates in the configuration you make with the MinimOSD will not be saved. The OSD output end must be powered with 12v and the other end is plugged to your laptop with an FTDI cable.  Like so:

minimosd config setup
minimosd config setup

Use the configuration tool to set up the RSSI values (in Panel 1). Make sure you write the configuration to MinimOSD.  On the main ‘Config’ panel make sure that you’ve set the ‘RSSI Channel’ to Channel 8… AND make sure the RSSI Enable RAW is checked.

minimosd rssi setup
minimosd rssi setup (the RSSI enable raw must be checked to get raw values)

Save the configuration, remove the MinimOSD, plug it into the Pixhawk cable and Vtx/Camera cables and power up your system.  On the OSD screen where you’ve set the RSSI to be, you should see a number.  Take note of this as this is your ‘maximum’ link quality value.   Unplug your transmitter and take note of the value.  This time you should see a smaller number.  This is the minimum link quality value.  For my setup, the highest was 1793 and the lowest was 1056. I just set it to 1800 and 1050 since the OSD is limited to steps of 10.   Now power down the system, disconnect all cables, connect 12v power source to the MinimOSD and plug back the MinimOSD to your laptop.

6) Update the MinimOSD PWM Min and Max RSSI Values.  Finally,  fire up the MinimOSD CTools again and change the Minimum and Maximum RSSI values to the one you got in step 5.  Also set uncheck the ‘RSSI Enable Raw’ so you can see the values in percentage format. Save the configuration and test.

Spektrum DX6i + EzUHF Receiver + HKPilot32 (aka PixHawk) Channel Mixup

The HKPilot32 (and other PixHawk variants) use a single “muxed” connection from the receiver to the AP.   What I was not ready for was that the channel assignments were all totally mixed up.  The throttle channel is now registering as roll (ie aileron), the roll as pitch (elevator), and the pitch as the throttle!  only the yaw channel remained.

Here’s the stock channels using the latest ArduPilot:Plane firmware (3.1.1):

Roll (Aileron) – Channel 1
Yaw (Rudder) – Channel 4
Pitch (Elevator) – Channel 2
Throttle  – Channel 3

The main issue here is that the channels are fixed on my transmitter (a Spektrum DX6i).  A quick check online shows that the consensus seems to be to change the assignment on the transmitter (oh boy) and not on the AP.  At any rate, this is not viable for me right now.. so I have to implement it on the plane.

The correct parameters to change in either AP Planner or Mission Planner are:  RCMAP_YAW, RCMAP_ROLL, RCMAP_THROTTLE and RCMAP_PITCH.

While these parameters are visible in both applications, for some reason I cant save it with AP Planner and the channels refuse to be reassigned.  The following worked with Mission Planner (v1.3.11):

Roll (Aileron) RCMAP_ROLL – Channel 2
Yaw (Rudder) RCMAP_YAW – Channel 4
Pitch (Elevator) RCMAP_PITCH – Channel 3
Throttle  RCMAP_THROTTLE – Channel 1

Note that this is only for the hardware combination above and may be different in other systems so a little trial and error may be required. Also, while available, changing these settings are not recommended for APM2.5/2.6.

Configuring RC5808 5.8Ghz 8-Channel Video Receiver for FPV

The RC 5808  is a simple 12v, 8 channel video receiver with a  single Video output for a monitor or goggles.  I’ve had mine for over a year and I’m completely happy with it.

RC 5808 Receiver
RC 5808 Receiver

The following channels and its frequencies are supported:

CH1 5.705 GHz
CH2 5.685 GHz
CH3 5.665 GHz
CH4 5.645 GHz
CH5 5.885 GHz
CH6 5.905 GHz
CH7 5.925 GHz
CH8 5.945 GHz

In order to change the frequencies, change the pin positions found on top of the receiver:

RC 5808 Receiver
Figure 1: RC 5808 Receiver Channel Assignment

The pin combination assignment to change the channel is found at the back of the receiver:

RC 5808 Receiver
Figure 2: RC 5808 Receiver Channel Pins

To change the channels, position the pin to closed or blacked out half.  For example, figure 1 above, is set to use channel 8 (with reference to figure 2).

The HobbyKing HKPilot32 Stripdown

I decided to bite the bullet and go with the HobbyKing HKPilot32 instead of the Pixhawk for the reincarnation of my Skywalker FPV rig.  By most accounts the HKPilot32 works as advertised and why shouldnt it? it has the same design and uses the same chips as the open source Pixhawk.  Thank you open source and market forces!

Here’s the content of the packet (L to R: USB cord, Servo wire, Power Module, the HKPilo32, cables for the gps, buzzer, arming button, stickers and vibration pads, free memory card/usb adapter and extension board) and a 4MB sd card pre-installed in the device. The only major downside is it does not come with the 6-pin cable needed to connect the HKPilot to the  Quanum Lea-6H GPS.

HobbyKing HKPilot32
HobbyKing HKPilot32

What surprised me is the size of the HKPilot. it has the same dimensions as the APM 2.6 which is great.

HobbyKing HKPilot32
HobbyKing HKPilot32

I’ve heard about the poor quality of the soldering and board layout of the HKPilot.. personally, for the price, I couldnt care less  as long as it works reliably.  Anyway, out of curiosity I checked the board.

HobbyKing HKPilot32 board
HobbyKing HKPilot32 board (back)

and front:

HobbyKing HKPilot32 board
HobbyKing HKPilot32 board (memory card on the left)

In my opinion, the board design and layout is not bad, a bit dirty to be honest but not bad. The soldering while not topnotch seems to look solid  enough at any rate.. of course I’m comparing this to the usual hardware I see (computing and networking appliance’s boards).  You can judge for yourself above.

So does it work?  so far yes, I was able to load the latest ArduPlane firmware and didn’t really have an issue connecting MissionPlanner (except I had to set the connection speed to 38400)

HKPilot32 with MissionPlanner
HKPilot32 with MissionPlanner

Looking forward to setting this up for flight!

 

 

Skywalker 1880 2013/2014 T-Tail Version Mods part 2 of 2

To complete the modifications (see part 1), I felt that not only should the attachments be secure but it should also not require too much effort to remove the elevator.   The plastic plate that will be glued to the elevator has a plastic tab that gets ‘locked’ to the plastic plate on top of the rudder.  To remove the elevator one needs to ‘lift then pull’ that piece of tab.  If you ask me, its too small and requires some unnecessary effort which can damage the damned thing.  Here’s what I mean:

Skywalker Tail Mod
Skywalker Tail Mod

It would have been great if they added more plastic to this tab.  At any rate, the solution is straight forward, get a paperclip or metal cable tie (my preferred choice) and make a small hole near the tip of the tab like so:

Skywalker tail mod
Skywalker tail mod

And here’s the finished mod.. which can be easily accessed using whatever tool is at hand.

Skywalker tail mod
Skywalker tail mod

Skywalker 1880 2013/2014 T-Tail Version Mods part 1 of 2

The updated Skywalker RC Plane 2013 1880cm version I got from FPVModel.com came with a T-Tail configuration.  That is, the elevator sits on top of the rudder as opposed to being wedged at the base of the rudder.  One of the things I noticed was that the locking mechanism used to connect the elevator to the top of the rudder requires some work as there is simply no way we can make the 2 plastic plate parts to lock.  For this a dremel and some sanding paper is your best friend.

Here’s what I mean by the locking issue.

Skywalker Elevator Attachment
Skywalker Elevator Attachment

there is simply no way those notches will get in without breaking the plastic:

20141017_064943

The solution to this is to dremel or sand the level section (left of the circle above)  to provide space for the raised notch to slide on.

Strengthening the Tail Section

I also decided to strengthen the connection by adding the a screw which goes on top of the elevator to a washer and bolt under the plate that will be glued to the rudder.

For this you’d need a screw with a bolt and 2 washers.  What worked perfectly for me is a 3.5cm screw.  It just has enough length to cover the thickness of the elevator and the two connector plastic plates between the rudder and elevator.

Skywalker Attachment Mod
Skywalker Attachment Mod

To create the perfect fit do the following (note: this also assumes you have not glued the plates yet to the elevator and rudder):

1) Create a small hole on the lower plate.  The lower plate is the plastic plate which attaches to the rudder.  You’d want to make a hole just in front of the X studs of the plastic to prevent touching the wire channels (see picture below). Create a hole just enough to fit your screw.  A reaming tool (or the exact sized drill bit if you’re using a dremel) is perfect for this type of job as you want to have the exact ‘fit’. Again you dont want the hole to be too big.

2) Attach the two plates together.  I assume you have already dremeled or sand papered off some of the plastic for a good snug fit.  After attaching, get a marking pen and mark the upper plate through the hole made in step 1.  Remove the plate and make the same sized hole which is marked by the pen.  I did not do this in one step as I’m using a reaming tool which has a gradually increasing diameter which is not a good idea.

3) Glue the washer and bolt. This one requires some steady hands, since we will be inserting the screw from the top, the washer and the screw must be located under the plate of the rudder.   To do this, join the two plates together and insert the screw from the top (ie elevator plate) and insert the washer and bolt on the other end.  Dont screw it all the way, instead just screw a bit so the washer and bolt wont fall off.  Glue the washer first by using a medium fast acting glue (the 5 Minute Epoxy is perfect for this).. just put a small amount of glue on the plastic and away from the hole, just enough for the washer to be securely locked to the plastic.  Slightly add pressure to the glueing process by pulling on the screw so the bolt will be pressed against the washer. Turn the screw every now and then to make sure it and the bolt are not glued in as well.

Allow the glue to set (about 30minutes), do the same to the bolt.. again just enough glue around the edges to set the bolt on top of the washer.  After that has set add some a piece of plastic or plywood (in my case both) to add additional strength and secure the washer and bolt to the lower plate.  Here’s how it looks like, take note of the location of the bolt relative to the studs of the lower plate.  I had to dremel a bit of the plastic so the washer and bolt can fit.

Skywalker Tail Mod Bolt and Washer Mod
Skywalker Tail Mod Bolt and Washer Mod

 

4) Create ingress hole on the elevator.  This requires a bit of good guesstimating.. first remove the screw and attach (without gluing) the elevator to the plates.  Screw the screw from the the other side (ie from the bottom of the bottom plate where you attached the washer and bolt) and really slowly turn the screw make small adjustments to your angle to make sure it comes out centered and on top of the elevator.  Once you’ve done this, remove the screw and screw it from the top and you should be able to have a good straight path right through the washer and bolt at the bottom.  Here’s how it looks like:

Skywalker Tail Mod
Skywalker Tail Mod

5) Add a Base Plate on top.  Finally look for some small plastic to glue on top of the rudder as the base of the screw like so:

Skywalker Tail Mod
Skywalker Tail Mod

Add a washer before inserting the screw.  This mod will add a good solid connection between the rudder and elevator.

And in part 2, I added a some leverage to easily pull off the horizontal stabilizer from the rudder (see here).

Boscam TS582000 5.8Ghz 2W 8 Channel VTx for FPV

This is the manual of the the Boscam TS582000 is a powerful 5.8Ghz VTx.  The best thing about this transmitter is its listed output obviously.. but that’s the only advantage, in my opinion and one could get a lower powered transmitter which can probably get almost the same range. As effective range is affected by several factors afterall.

Here are my comments about this transmitter:

1) Replace the Stock Antenna. Using this with the stock yagi antenna, is pointless because of the donut hole effect which results faded signals when the plane is above you.  It works best using a circular polarized antenna like the Immersion RC Spironet.  In fairness, this holds true to all 5.8 transmitters available in the market today.  All I’m saying the cost difference of putting in a circular polarized antenna (instead of the yagi) for such a powerful transmitter would probably have made little price difference.

2) Limited Mounting Options. You’d think by now that the VTx’s which are being sold as for ‘FPV’ would have better mounting options, but they dont.  Again, this holds true for almost all of the antennas out there.  In my case, I had to reverse the antenna so I can use the mounting screws of the fan to screw it to a custom mounting using a phone card.

3) Clunky Channel Panel. Unlike other transmitters, this particular one is a pain when changing channels.  Not only are the switches really small, there’s no visual feedback to show which channel is active.  Other transmitters have a small digital-like screen to show the active channel which is really handy specially in the field.  In a couple of instances I had to embarrassingly request other FPV flyers if they can change their channel as the 2W is overwhelming everybody and as I said changing the channel on this transmitter is a real pain in the @ss.

Here’s the manual of this transmitter:

Boscam TS582000 Manual
Boscam TS582000 Manual
Boscam TS582000 Manual
Boscam TS582000 Manual

 

 

The Aero-naut (aka TBS) Folding Pusher Prop Set

Finding the right pusher propeller set can be frustrating, specially if nobody can be certain if it will “work” in a pusher configuration.  It turns out, Team Blacksheep has exactly the propeller set I’ve been looking for which they stock for their Zephyr flying wings.  It’s the Aero-naut Folding Prop Set which seems to packaged specially for Team Blacksheep.   At $29.95 it’d be better worth it.

Here’s how  it came in:

The TBS Prop Kit

And some very sound warning for folding props.. which I’m posting here.  My main issue really with my old SW set up was that the one piece prop was bulky when putting the rig in its box for transport.

20141021_213942

Ok on to the description of the set.. the prop centerpiece has a 6mm hole (for the shaft) and 8mm space between the prop arm for the prop attachments. The CF props that comes with the kit is 10×5 size. The two black stopper strips which goes to the front and back of the centerpiece to help prevent ‘over folding’ is made out of some plastic, which looks tough enough and which I think is unique to this set.

20141021_214109

Here’s the measurement of the prop arm spacing using a high tech device.

20141021_214259

And the prop set compared to a regular 10x5e prop.

20141021_214720

 

I’m not so sure how much “push” this particular set can provide compared to the one piece prop. The folding prop seems to have 10-15% less surface area.  We’ll know soon enough. Anyhow, the manufacturer of the centerpiece and the props, auro-naut.de, has bigger sized props just in case.

And We’re Back!.. with the Skywalker 1880 From FPVModel.com

My replacement FPV platform is finally here.. after losing the 1900 Skywalker 2014  due to a bad GPS caused by the vibration of  a bad motor (bad bearings) activated by a bad operator (yours truly who ran out of TX juice), I decided to use the same platform but this time with better components (specially the motor!).   The platform remains the 1800 Skywalker 2013 CF tail boom (and wooden pan for the FPV cameras) with the elevator on top of the rudder but this time from  FPVModel.com.

Here’s how it came in:

20141013_102257

and the contents:

20141013_102659

 

Here’s the Lowdown:

Wings

1) The 1880 wings seems to be thicker and looks like it also has a slightly longer root chord than the 1900 wings.

2) Unlike the 1900 wings it doesn’t come with a CF strip on top for added strength although I don’t think its needed considering its thickness and the fact that it also has a longer dihedral, covering 1/3 of the wing.

3) Because of the large dihedral, this wing doesn’t come with flaps, it only has enough room for the the ailerons.

Tail Section

1) This is the T-tail version, with the elevator attached on top of the rudder.  I think this is a good idea, in my SW 1900 the elevator is attached to the base of the rudder. This has a tendency to get skewed by the tall grass I occasionally land in.

2) The connecting plastic mechanism to snap into and remove the elevator to the rudder seems innovative although looks a little bit flimsy to me.  Looks like I need to do a little mod on this.

All the usual parts seems to be complete.  Will post the components list next.

 

 

Skywalker Fly-away $#^$@!

Lost the Skywalker with the Gopro 3 Black and Mobius cameras a-blazing yesterday.    The first indication I was having a problem was the LCD screen on the monitor blacking out.  At this point the plane was not flying very high nor far.. probably not more than 80′ up. The control response were also squishy but I was able to manage to align the plane on the field for a landing but was coming in too high and decided to make another round which was a mistake, at this point even the EzUHF transmitter shut down. This could mean 2 things either the 12v BEC I used for power distribution for the EzUHF transmitter, monitor, DVR and VRx has failed or the LiPO has discharged.  Running back to the field tent to get a spare battery I saw the plane do an RTL and do at least one circle over the launch area.. so far so good.  Couldnt find the spare battery for the transmitter and decided to disconnect the rest of the electronics and just power the ezuhf, at this point I can still the hear the buzzing plane above.. then silence.

Went around surrounding area for a couple of hours but couldn’t find it.

Lessons for this one:

1)  VERIFY, VERIFY that the transmitter battery is at least at 90%.. this is the 3rd flight I made for the day and I remember starting with about 80% (I’m using a Tiger 4S 2800), usually I charge this the night before but not yesterday =(  Checking the battery after showed it was only generating 11.1v.  I completely under-estimated the power drain by the system.
2) Nevertheless, the APM2.6 seems to have gone on a fail safe which dropped to the RTL. I was expecting the plane to loiter above after reaching ‘home’ waiting for a signal (or the battery drains) but this did not happen.  The correct behaviour should have been with long RC signal loss, the APM 2.6 should loiter or RTL and Circle and not make do a hardware fail safe, either that OR the ESC has fail-safe’d, and finally;
3)  At the first sign of power and control issues…land!

G R O A N.