Saturday, 23 June 2018

Scratch-built Micro Skyhunter

3mm depron version of the wonderful little twin boom Eachine Micro Skyhunter.
Dimensions are similar to the original but with a slimmer fuselage.
1300mAH 3S battery and FPV gear.
CG best around 35mm.
The final version has a shorter nose, reinforced horizontal stab and rounded wing tips

Build video

Maiden flights

Mods Q&A and FPV

Thursday, 22 March 2018

Volantex Ranger 1600 AIR3 iNav setup

Here is how I mounted the AIR3 board in the Ranger.

The board is rotated 180º (facing the tail) making the USB port accessible (Requires board alignment - YAW 180º in iNav configurator) Mounted on a piece of corplast which jams under the wing and is taped to the ply shelf for easy removal.

I drilled a hole in the top of the body to pass the GPS cable through.

Board and servos are powered by a 5V 3A Carbonbird BEC via a power distribution cable.
FrSKY X6R receiver connects to the board by SBUS.

ESC sits on the floor to keep some distance away from the AIR3 and Rx.

Tuesday, 20 March 2018

Volantex Ranger 1600 AIR3 iNav

The Volantex Ranger 1600 or 757-7 is almost the perfect plane for me. The 2m version 757-8 is just as good and uses the same fuselage.

(Don't confuse this beauty for the terrible 757-4 Mini Ranger 1350mm. Review here)

The 757-7 has a tough plastic fuselage, 1600mm wingspan, no bad habits and excellent quality hardware. It's tough enough, aerobatic enough and glidey enough for my requirements.

Perfect for FPV cruising, aerial video, slope soaring and sport flying.

Currently I have mine setup with a Paris Sirius AIR3 F3 flight control board running iNav 1.7 from Carbonbird, FrSKY X8R reciever and 40A current sensor.

Initially the motor was a Turnigy Aerodrive 2836 1100kV with the stock 8 x 4 prop and 40A ESC
Now changed to an NTM Propdrive 2836 1200kV for better bearings and bolt on prop shaft.

With a 3000mAh 4S battery it cruises around on 3A with 25A flat out.

iNAV configurator CLI dump here

My preferred iNav modes

Ranger 1600 review

Ranger 1600 flights

Ranger 1600 sloping

Ranger 1600 motor mount mod

Ranger 2000

Banggood links

Sunday, 4 February 2018

My FPV gear

FPV Goggles, cameras and video transmitters.

My goggles are Aomway Commander V1
Much cheaper than FatSharks and have a decent quality 16:9 picture and DVR recording. Supplied with excellent patch and cloverleaf antennas and the diversity receivers give great range. Range of 3km on 200mW is possible in perfect conditions.

I strongly recommend trying goggles on before you buy. They must suit your vision, Inter Pupilary Distance IPD and the shape of your face. Idealy I would like a bit more IPD and focus adjustment to suit my vision and big head.

For normal reading I need +1.0 diopter glasses.

Or in the big screen format I like the Headplay SE box.
I needed to fit the included RHO narrower view lenses to see the screen clearly.
Spectacular viewing experience but limited by the lack of diversity receivers. Supplied with an add-on DVR unit

My preferred antennas are 5.8GHz Right handed circular polarised Aomway  clover leaf

They come in SMA or RP-SMA connector style,  and you need to choose the correct style to match your goggles and video transmitter. SMA antennas have a prong, RP-SMA have a hole.

My preferred Video transmitter (VTx) is the TS5823L  Eachine 200mW 40ch TS5823L 
It is compact and has a single push button to select channels and a single digit LED display.
The wires are stiff and delicate so need to be handled carefully.

There is a TS5823S version with a 5V regulator onboard, but I found this produced diagonal lines in the FPV feed.

Antenna connector is RP-SMA

Video transmitters come in a variety of power ratings.
25mW for small park flying and racing
200mW for general FPV
600mW for longer range, but be aware this will cause more interference to others. Only use if no-one else is flying FPV nearby.

VTx connection
I solder on a female servo-style connector to the Red, Black and Yellow wires for Power, Ground and Video signal. The other two wires are for Audio which I don't use.

I like a dedicated FPV camera like the Runcam Sparrow or Eagle 2 Pro. They are both swappable from 16:9 to 4:3 aspect ratio and have wide dynamic range and battery voltage displayed on screen.

It is possible to use the TV out signal from an HD camera like a Mobius or GoPro, but it is not as safe as a stand alone FPV camera.

More information on that here - Other FPV cameras 

To connect the camera to the VTx I solder on a male servo-style connector to the +V, Ground and Yellow. If the camera also has Voltage display capability I connect the Voltage sensor wire to directly to the Red +V wire so I can see the flight battery voltage on screen.

The camera and VTx can be safely powered from the 3S or 4S flight battery. I use a servo style Y lead with one end changed to a female balance plug (3S or 4S as required) for power. The Y lead provides flight battery voltage to the camera and VTx as well as passing the video signal from the camera to the VTx

For a swappable FPV rig I use heat bent PVC plastic to make up a small mount.

This compact FPV backpack can be mounted with tape or velcro on to any plane.

All of this gear is available from Banggood via the links above, and these category links
BANGGOOD website

Friday, 26 January 2018

Aomway Commander V1 Head tracker module

The Aomway Commander V1 FPV goggles have the option of adding a head tracker module. This means you can pan and tilt an FPV camera by moving your head around.  The head tracker module sends the head movement signals to the Taranis radio via a cable connecting the goggles to the Taranis trainer port. Then the Taranis transmits the signals to the reciever on channels 7 and 8 as TR7 and TR8, trainer inputs.
The Commander V1 Advanced version comes with the head tracker installed. I have the non advanced version so needed to buy and install the module myself.

I purchased it direct from Aomway and it came with the trainer cable, ribbon cable, mounting screws and spare push buttons. They don't actually have an online shop but send an email to "Sales" to enquire about purchasing.
I also bought a replacement DVR ribbon cable to replace the cable I had previously damaged. They are quite delicate and you must be very careful not to jam the cables when reassembling the case.

Fitting the headtracker module

One screw in the nose area allows the face plate to be unclipped. Two screw underneath hold the case together. 

Open carefully and don't over stress the ribbon cables.

There is only one spare port for the headtracker to plug in - right side, middle port, and only one way it will fit on to the mounting posts. 

I removed the top cable for better access while fitting the module. 

DVR ribbon cable replacement

Here is my damaged DVR cable. 
It was jammed between components during reassembly after I opened the goggles for a peak inside.

Push the grey clamping bar to the left to release the cable

VERY carefully reassemble the goggles making sure no cables are caught between components. The DVR cable can get in the way of the SD card slot.

Video version with the head tracker working

Tuesday, 24 October 2017

iNav fixed wing tips

October 2017 - Betaflight is the most recent firmware for flight control boards (FCBs) and iNav is the GPS enabled
re-write of Betaflight which also caters for fixed wing models.

All the setup is done using the Chrome App called iNav Configurator. Works on PC and Mac as long as you can locate the correct drivers for the board you have. All the information on iNav is kept in the iNav Wiki on GitHub

I'm quite new to all this auto pilot stuff and there is a steep learning curve, so I thought I could pass on what I have learned so far.

So far I have experience with the Paris Sirius AIR3 F3 board with GPS from Multiwiicopter

and the Omnibus F4 V1 board and Ublox Neo M8N GPS module from Banggood.

The value of the AIR3 board is that it comes mounted in a gel damped housing with all the connectors and GPS sensor, and it's pre-loaded with the latest stable iNav firmware. Most of the tricky stuff is already done for you.

The AIR3 is an F3 board and doesn't have a built in OSD, but an addon OSD is available. The AIR3 OSD is configured using the MWOSD Chrome App, and partially by using your transmitter sticks.

If you're handy with a soldering iron and want to do it all yourself, you can follow Matt Ogbourne's video series on the Omnibus board setup. You will have to do all the soldering, firmware flashing and setup yourself. The Omnibus F4 does have a built-in OSD, which is configured in the iNav Configurator.

About Flight Control Boards
The connections to FCBs are a little more tricky than normal ESC/receiver/servo connections because FCBs are more sensitive to incorrect or fluctuating voltage supply. With voltage spikes, FCBs can shut down, brown out or reboot causing total loss of control of the model.

It is highly recommended that the board and servos are powered by an accurate and stable 5.0V BEC like the AIR3 iNav BEC. You need to make up a power distribution cable so the BEC can plug into the board, and power the servos separately. As the 5.0V is being supplied to the FCB by the BEC you must disconnect the 5V line (red wire) from the ESC. Not a good idea to have two power sources for the FCB. Then all the signal wires from the servos and ESC connect to the board. The ground wires can either connect to the BEC or the board.

Another recommended precaution is to plug a voltage smoothing capacitor into your FCB, like this 3300uF 25V from MultiWiiCopter. The capacitor connects to any spare output pin-set across the power and ground pins, and absorbs any voltage fluctuations. Can also be plugged into receivers for added safety.

If you want to live dangerously you can just plug the servos and ESC straight into the board. like you would with a receiver, but you are only one voltage spike away from a crash.

Transmitter setup
You do not use any mixing, rates, expo or trims in your transmitter.
Just program in 100% for each stick and whatever Mode switches you need.

My setup on the Taranis is:
Ch1 100 Aileron
Ch2 100 Elevator
Ch3 100 Throttle
Ch4 100 Rudder
Ch5 Switch E (Arming)
Ch6 Switch A (Air, Horizon and Angle modes)
Ch7 Switch D (Loiter and Return to Home modes)
Ch8 Switch C (Pass through and Launch assist modes)

iNav tips
There are three types of Modes available in iNav.

Full control modes

Passthrough Mode
Normal flying with no stabilisation, only the Expo value in iNav is used. If something is going wrong with the FCB or GPS switch back to this mode to take control.

Air Mode
Slightly stabilised, full control. Always active when no other mode is selected

Stabilisation modes 
These are Gyro and Accelerometer driven modes that rely on the board being level when the plane is in level flight attitude. Most planes fly level with the nose a few degrees up, so the board may need to be tilted down at the front, either in the mounting position or in iNav setup board alignment. Actually what we need is the board mounted level with the airfoil chord line a few degrees up. It varies with different wings and different flying speeds so to get this right you need to fly the plane and make appropriate adjustments to the board alignment in the field, without using Transmitter trims. See Plane Trimming Tips below.

Angle mode
Fully stabilised, bank and pitch angles limited. Can't do loops and rolls in this mode.

Horizon made
Starts off like Angle mode but allows greater control as the sticks are moved further.

Launch Assist Mode
This is a magic mode. Select Launch Assist, arm the board, advance the throttle to a good launch percentage (the motor will not spin up yet) throw the plane and the motor will spin up 0.5 sec after the throw acceleration is detected. The plane will climb for 5 sec then switch into any other mode you have selected, or until you move the sticks. I have used Launch Assist and RTL combined, so I can can launch and let the plane circle above without picking up the transmitter. A big crowd pleaser.

It's important to get the switch sequence right for Launch Assist to work.

GPS modes
These are GPS controlled modes, and they can be combined with the Stabilisation modes.

Altitude Hold
Does what it says, holds the flight path at the Altitude when selected. Very useful when combined with Angle or Horizon modes for level and stable flight paths.

Position Hold
The plane will circle around the point where the mode is selected, at the radius selected in iNav setup. Relies on a properly aligned FCB for altitude. Best to combine with Altitude Hold mode for a very useful Loiter mode.

Heading Hold
Uses rudder to hold the flight path to the heading when selected. Combine with Altitude hold for fixed heading and altitude flight path.

Return to Launch (RTL)
This is what it's all about. Enter this mode and the plane will fly back to where it was armed, at whatever altitude and throttle percentage you have setup in iNav, then circle overhead at the iNav setup altitude and radius (or even land automatically if you're game)

Failsafe RTL
For me this is the main reason for using iNav. Failsafe can be setup to go into RTL mode, meaning that if you lose radio contact with your plane it will fly back home.
On FrSKY X series receivers I set the failsafe to No Pulses, then in iNav - Failsafe RTL - Don't Land.

Important plane trimming tips
The correct way to trim your plane is to adjust the push rods and servo arms mechanically so it flies level and the control surface throws are OK with no trims or rates needed in the transmitter. Then you trim the FCB alignment, either physically or in iNav (using a laptop in the field), so the plane flies level in Angle or Horizon modes.
If you don't do this the plane will behave differently depending on which mode you're in. It might, for example, go nose up in Passthrough mode and nose down in Horizon mode. Of course GPS modes can mask any trim issues.

Here are all my iNav related videos on YouTube - iNav Playlist

Thursday, 10 August 2017

The Boxler - Packing box plane

For years I have wanted to make a plane from an RC plane polystyrene packing box.

In the recent Hobby King sale I bought a Bix3, so here was my opportunity to give this project a go.

For speed and simplicity I decided to make a simple 3 channel motor glider with no ailerons. I covered the foam with packing tape and used fibre reinforced tape like spars on the wing and fuselage. I also decided to try a flat wing with no airfoil and dihedral tips.

This video shows the build from start to finish.

Here's the maiden flight which went better than expected.

I then made a hot-wire cut Clark Z airfoil wing to compare to the flat wing.

The airfoil wing had a much better glide slope and smoother flight performance.

Here are some mad wing tests using the flat and Clark Z wings.

Dimensions in cm

Length 100cm
Flying weight 590g
with 1300 3S Lipo
Motor 2822 1450kv
7" x 4" prop