Let’s build the Ar Mini v2

Opening the box you’ll find almost everything you need and so we get right to it. Yet let’s point out, what this build be we aiming at. Here are some key features:

  • I want to cruise that wing! No speed monster
  • Long fly time
  • Crossfire / 5G8 setup
  • It will run iNav
  • detachable wings 😉

Not that much work to do

As we take the Ar mini PnP as a starting point, there is much time to go into the minor details that will make the wing a lovely little piece of foam.

Motor and ESC

Shortening the wires and swapping the esc to something more light weight

The stock motor comes with the smaller banana jacks which per se is totally fine. Yet for me this is not needed as the wires are far to long and the new ESC will get the wires soldered directly. I ended up with shortening the three wires from the motor down to about 2.5cm which turned out to be enough to make the ESC fit through the hole on the rear.

You should consider to solder some low-ripple capacitator on the ESC as to reduce possible noise coming from it!

Embedding the GPS unit

The BN-180 GPS is my all time favorite for the wings. Super tiny and a fast fix convinced me to skip the BN-880 for it as it offers all what I need for iNav. Usually I get 20+ satellites when I start up the wing!

Best place to embed it turned out to be on the right rear as there is plenty of space and the wires will run to the Matek F411-WSE from a little tunnel. Here’s how I did:

I marked the shape of the BN-180 onto the foam and used a dremel to make that hole. Next I routed the wire to the center of the fuse and then connected it. Finally pushed the GPS in the hole and covered it with lamination foil, just to protect it a bit from moist. Some tape will do the same.

Making the wings detachable

One of my main goals for this build was to keep the wings detachable as it will make it very easy to take the Ar Mini with me while traveling. Yet I didn’t have the real need to disassemble it so far. But I could! 🙂

I used a strong zip to make the connections.

2cm from the leading edge, 3cm deep

On each wing i dug a hole about 2cm from the leading wing edge. Tho hole is 3cm deep. Then fiddle the Zip (or Velcro) in and fill it up with glue like UhuPoor and let it cure over night.

Next thing on the agenda is to drill a hole in the fuselage to route the zip through:

On the inside of the fuselage I glued the holding part of the zip after I was sure it would fit. To make the glue hold better I added some pressure to it.

Cool color scheme

Like on the Ar Mini v1 I wanted this new build to stand out from the rest a bit. While searching for the right color on eBay I ended up with a intense yellow foil which I guess is for car wrapping or something like that. I’m pretty sure it’s not the most lightweight foil but … it’s cool 🙂

First thing to do is to dryfit the foil- then we will work the wings with some sanding paper and finally attach the foil.

So that’s how it looks. We will go for it like that. But as mentioned we need to sand down some spots on the wing to get rid of any air bubbles. Have a look

On the first image you’ll see the spots I sanded. These are the spots where the tiny remains of the nozzles from production. No matter how good you apply the foil: they will push it up and create small air bubbles.

Then I attached the foil. It will glue by itself yet I took a hair dryer and added some head to it. The pattern on the foil is the foam beneath. The Final result looks like this:

Embedding the VTX into the wing

Originally the plan was to put the vtx into the fuselage like in v1 but as the vtx can get pretty hot by time, I changed the plan to have it in on of the wings.

The TBS Unify Pro32 will be embedded and do the job. As I wanted to get a good range out of this build, I thought, this would be the right one 🙂

As antenna I picked the iFlight Sigma 60mm MMCX which can be obtained with all kind of connections. Sadly I didn’t get the one with the angled mmcx connector. But on the other hand the antenna will hold and stabilize the VTX a bit.

I certainly have done better dremel jobs so far but this will do and as the hole is a bit narrow, I now simply can push the VTX in and it will stay there and even be supported by the antenna to stay in place! No glue or what so ever.

I like that little thing – it has a good performance and balances a bit on the drag of the Immortal-T on the other wing. The vtx has 4 wires (current, ground, video, smartAudio) with servo connectors on it so it is plug-able.

Crossfire NanoRX SE and some bling-bling

And as we need reception I make a hole for the TBS NanoRX SE on the other wing. Simply routed 4 wires out of the fuselage with servo connectors on it. That makes them easy plug-able just like the wing with the vtx.

Nothing fancy to see here … just some wires and an embedded TBS NanoRX SE 😉 so … lets do the Bling-Bling!

I picked up some WS2812B LEDs and made them fit unter the motor. Then simply wire them up to the F411-WSE on the LED pin. Within iNav I chose some colours and that’s it – now it’s ready to blink.

Adding a 4K cam to the nose

As you guys surely have noticed are all my latest videos (let say the last 3+ years) all in 4K resolution. That’s a choice I made for my self back then when I bought a new 4K TV for the living room. Of course I want to record my flights in 4K and for that I embedded a RunCam Hybrid in the nose cone.

I build v1 I even had the pan servo attached. But in this build I went back to nose as it provides more protection and is a less flimsy.

The RunCam Hybrid has a pcb with a dvr on it. Further is it nice and a bit better that the Tarsier. I made a post on that some time ago.

While the camera itself is placed in the nose cone the pcb sticks right behind it. Be sure to put a piece of tape over the SD card as on some situations it might eject and stay lost in the field!

I guess that’s about it!

perhaps some more facts about the build you see:

  • The motor spins a Gemfan flash 6042 prop
  • 3s setup running Li-Ion cells with 3000mAh
  • approved flight time is about 45min !
  • In normal conditions the wing will consume 2-3A for cruising
  • Radius is at least 6.5km ! … but I guess there is more in store- we will find out

I installed iNav v2.5.2 on it as I wasn’t that happy with v2.6 so far. Here is the DIFF! You can use it on your on responsibility:

# version
# INAV/MATEKF411SE 2.5.2 Aug  4 2020 / 10:29:28 (faaedc7cb)
# GCC-9.2.1 20191025 (release) [ARM/arm-9-branch revision 277599]
# JustFPV AR Mini V2

# start the command batch
batch start

# reset configuration to default settings
defaults noreboot

# mixer

mmix reset

mmix 0  1.000  0.000  0.000  0.000

# servo mix
smix reset

smix 0 3 0 50 0 -1
smix 1 3 1 50 0 -1
smix 2 4 0 -50 0 -1
smix 3 4 1 50 0 -1

# servo
servo 3 1000 2000 1484 -90
servo 4 1000 2000 1558 90
servo 5 640 2300 1448 100

# feature
feature -TX_PROF_SEL
feature BAT_PROF_AUTOSWITCH
feature MOTOR_STOP
feature GPS
feature LED_STRIP
feature PWM_OUTPUT_ENABLE
feature FW_LAUNCH

# beeper
beeper -RUNTIME_CALIBRATION
beeper -ON_USB

# map
map TARE

# serial
serial 0 2 115200 115200 0 115200
serial 30 2048 115200 115200 0 115200

# led
led 0 0,0::CTB:8
led 1 1,0::CTB:12
led 2 2,0::CTB:8
led 3 3,0::CTB:12

# color

# mode_color

# aux
aux 0 0 1 1800 2100
aux 1 2 0 1150 1250
aux 2 11 0 1775 1850
aux 3 10 0 1950 2100
aux 4 45 0 1350 1450
aux 5 37 3 1400 1600
aux 6 21 3 1675 2100
aux 7 13 2 1775 2100
aux 8 27 0 1975 2100
aux 9 42 5 1100 1400
aux 10 43 5 1400 1800
aux 11 44 5 1800 2100

# adjrange
adjrange 0 0 7 1100 1475 49 6
adjrange 1 0 7 1475 1550 18 6
adjrange 2 0 7 1550 1625 19 6
adjrange 3 0 7 1625 1700 20 6

# rxrange

# temp_sensor

# wp
#wp 0 invalid

# osd_layout
osd_layout 0 0 26 2 V
osd_layout 0 1 1 9 V
osd_layout 0 2 0 0 V
osd_layout 0 7 21 1 V
osd_layout 0 9 23 14 H
osd_layout 0 10 1 1 H
osd_layout 0 11 2 11 V
osd_layout 0 12 1 10 V
osd_layout 0 13 2 7 H
osd_layout 0 14 25 1 V
osd_layout 0 15 23 6 V
osd_layout 0 22 6 1 V
osd_layout 0 23 1 1 V
osd_layout 0 24 12 2 V
osd_layout 0 26 23 7 V
osd_layout 0 28 23 10 V
osd_layout 0 29 23 9 H
osd_layout 0 30 0 12 V
osd_layout 0 31 25 3 V
osd_layout 0 33 24 11 V
osd_layout 0 34 10 1 V
osd_layout 0 38 1 8 V
osd_layout 0 40 1 2 V
osd_layout 0 46 23 4 V
osd_layout 0 47 22 9 H
osd_layout 0 85 2 7 V
osd_layout 0 87 1 3 V
osd_layout 0 97 8 13 V
osd_layout 0 105 24 2 V
osd_layout 1 11 2 13 V
osd_layout 1 15 23 12 V
osd_layout 1 22 6 1 V
osd_layout 1 23 1 1 V
osd_layout 1 30 1 10 V
osd_layout 1 31 1 14 V
osd_layout 1 35 22 13 V
osd_layout 1 45 0 0 V
osd_layout 1 48 1 11 V
osd_layout 1 49 1 12 V
osd_layout 1 98 23 1 V
osd_layout 1 99 25 3 V
osd_layout 2 2 0 0 V
osd_layout 2 3 8 6 V
osd_layout 2 7 24 1 V
osd_layout 2 15 1 1 V
osd_layout 2 16 1 1 H
osd_layout 2 22 23 1 V
osd_layout 2 26 6 1 V
osd_layout 2 41 1 2 H
osd_layout 2 45 0 0 V
osd_layout 2 63 1 2 H
osd_layout 2 98 0 0 V
osd_layout 2 99 1 3 V
osd_layout 3 1 9 12 V
osd_layout 3 10 2 13 V
osd_layout 3 12 9 11 V
osd_layout 3 16 7 4 V
osd_layout 3 17 7 5 V
osd_layout 3 18 7 6 V
osd_layout 3 20 13 3 H
osd_layout 3 21 13 4 H
osd_layout 3 22 7 1 V
osd_layout 3 23 2 1 V
osd_layout 3 37 9 12 H
osd_layout 3 41 2 2 V
osd_layout 3 42 7 2 V
osd_layout 3 46 2 11 V
osd_layout 3 47 2 12 V
osd_layout 3 56 7 7 V
osd_layout 3 58 7 8 V
osd_layout 3 63 18 12 V
osd_layout 3 97 8 10 V

# master
set gyro_hardware_lpf = 188HZ
set acc_hardware = MPU6000
set acczero_x = 84
set acczero_y = 4
set acczero_z = -190
set accgain_x = 4106
set accgain_y = 4109
set accgain_z = 3999
set mag_hardware = NONE
set baro_hardware = BMP280
set pitot_hardware = ADC
set rssi_channel = 17
set serialrx_provider = CRSF
set motor_pwm_rate = 2000
set motor_pwm_protocol = ONESHOT42
set throttle_idle =  8.000
set failsafe_procedure = RTH
set align_board_roll = 2
set align_board_pitch = 28
set platform_type = AIRPLANE
set model_preview_type = 8
set small_angle = 180
set imu_acc_ignore_rate = 10
set applied_defaults = 3
set inav_w_z_baro_p =  0.350
set nav_rth_allow_landing = FS_ONLY
set nav_rth_alt_mode = AT_LEAST_LINEAR_DESCENT
set nav_rth_altitude = 10000
set nav_fw_control_smoothness = 7
set nav_fw_launch_accel = 1600
set nav_fw_launch_thr = 1800
set nav_fw_launch_timeout = 20000
set nav_fw_launch_climb_angle = 20
set osd_time_alarm = 35
set osd_alt_alarm = 2000
set osd_dist_alarm = 6500
set i2c_speed = 800KHZ
set name = Ar Mini V2
set vtx_band = 5
set vtx_channel = 7
set vtx_power = 4

# profile
profile 1

set fw_p_pitch = 10
set fw_i_pitch = 21
set fw_ff_pitch = 100
set fw_p_roll = 3
set fw_ff_roll = 34
set tpa_rate = 10
set rc_yaw_expo = 70
set roll_rate = 10
set pitch_rate = 8
set yaw_rate = 10

# battery_profile
battery_profile 1

set vbat_min_cell_voltage = 300
set vbat_warning_cell_voltage = 300
set battery_capacity = 3000
set battery_capacity_warning = 600
set battery_capacity_critical = 450


# restore original profile selection
profile 1
battery_profile 1

# save configuration
save

If you run into any trouble or I missed something important out, then just leave me comment below and I will reply.

Thanks for reading!

11 Comments

  1. Reply

    Nice build. I am building, flying, and crashing with iNav as well. I am running version 2.6.1. When I thought I had iNAV dialed in , while flying in Horizon mode I banked my AR Mini hard to the left and she went into an uncontrollable barrel roll. I switched to manual flight mode to minimize the crash but it got hairy. Only loss was the RunCAM splitcam nano. The ribbon cable did not take the impact well.

    Is there a problem with 2.6.2 ? Have you seen that before ?https://www.youtube.com/channel/UC6VJZbtXu0S4UVcIZ4nOCDg

    My r/c /drone channel is
    I’m going to try your iNav parameters. iNav profiles are the same across controllers, right ?

    Where did you find the foil to dress up the AR Mini ? Looks great!

    • Pairan

      Reply

      Hey Jerry- I’ve tried to escape the spiral of death. Acro Mode is the key and no Inputs! The get enough airspeed and get back in business

      The foil is intended for car wrapping – you’ll find it on eBay. So did I 😉

  2. Rephan (aka quetiano on youtube)

    Reply

    Good day to you.
    Finally I’ve built and have been experimenting with the Ar mini wing and I’ve tried a few motors to get the longest flight time, but i can’t get over 42 min ( haven’t tried the emax mt2204 2300kv yet, and windy almost everyday, using 3d cruise, have to set that up with throttle control though for efficiency)… My ar mini wing weighs approximately 444g with 18650 3000mah 4s samsung 30Q battery pack and testing the t motor f60 pro iv 1950kv with 7050. Very noisy and close to the body and I’ve read some time ago that it’s inefficient to have the prop so close to the body.
    My question is, regarding flight time and amp draw while cruising, how inefficient is that, is it a huge flight time hit?

    • Pairan

      Reply

      Rephan, good to hear yours is up in the air. For efficiency try a 6” prop. We have cut a little piece of foam of the wings so the prop won’t chop into it on a rough landing or such.
      A buddy of mine uses the emax eco 2306 with 1800kv! He says it’s a blast with 7” and 4s – great speed and heaps of fun. That again will take some flight time while speeding but if fly a bit more economical then there ist sure some time to win.

      7” props on that little thing is only good when a matching motor spins it! A 2306 is commonly heavier than a 2204/5 and needs more weight in the nose to balance out.

      Hope this helps you a bit otherwise raise a hand and we discuss further 😉

  3. Rephan (aka quetiano on youtube)

    Reply

    Thank you so much for your reply.
    So…
    1. I’m confused about you mentioning to use the 6″ from the 7″ prop because isn’t it that the larger the prop, the less the amp draw? Unless you mentioned that because of the pitch of the prop that I’m using on the 7050?

    2. Cutting foam is better than adding spacers to the motor because adding spacers will change the cg, so you have a photo of where and by how much to foam the foam to allow the motor and prop to breathe more easily?

    3. Does it make a huge impact on flight time cutting the foam to allow the motor and prop to breathe more easily?

    • Pairan

      Reply

      1) 7” is bigger than 6” and with that fans more wind. But in order to swing that prop a capable motor is needed or the prop will cause higher amp draw and heat up the motor as it can’t comply to the signals from the esc – therefore 6” is better as a 7” if you got for a 2204/5 motor with 2300kv.

      2) if you take your mounted prop an bend it a bit towards the foam then you’ll get an idea of what could happen on a rough landing: the prop will smack into the foam and chop it. To prevent this, simply could 1cm and the narrower part where the prop would strike. Doesn’t have to be that much. But a little clean cut is better than glued foam and battle scars 😉

      Have a look at my Ar mini when it’s shown from the top and you’ll get the idea

      3) none!at least not on the Ar mini.

      • Rephan (aka quetiano on youtube)

        Reply

        Thank you for the awesome explanation of the prop, i never knew that until now, i learn something new all the time.

        I’ll use the 6040 prop then and cut some foam from the ar mini and check the flight time.

        Thank you Pairan for your time and effort in helping me, much appreciated!
        Ps: any recommendations of planes to purchase and set up that can fly over an hour with a single li ion 3s/4s battery pack,let me know?

          • Rephan

            Greetings and hello Mr Pairan
            Just a follow up on todays flight with the Ar Mini, I used the 6040 prop on the t motor f60 pro iv 1950kv, and it decreased flight time quite a bit, from over 40 min to 33 min, so using that larger prop (7050) does help with more flight time on this t motor.

          • Pairan

            Thanks … good to know that the F60 1950kv is better with a 7″ 🙂

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