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Project Notes

#720 HIDF Twin Otter Recon

DHC-6 Twin Otter from Revell (04901 in 1:72), as seen commandeered by HIDF Gendarmerie and pressed into service as a reconnaissance and special ops platform. For the Micro Machines Podcast HIDF GB.


Here’s a quick demo..



I’ve had the Revell DHC-6 Twin Otter No. 04901 in 1:72 sitting in my stash for a while. It’s an “OK” kit and I love the float configuration, but I was searching for diorama inspiration.

When I head about the Micro Machines Podcast Horizon Islands Defense Force Group Build I thought .. ahah!

Paint Scheme

Main colors used for the plane:

Feature Color Recommended Paint Used
interior gray   H61
exterior - under coat 1     H8
exterior - under coat 2     H4
exterior     H80 (was H303?)
HIDF flag     H1, H4, H5, H26

Ground-work was a mixture of Vallejo Model Color and Mr Hobby Aqueous.

HIDF - Horizon Islands Defence Force

HIDF comes from the Arma3 game. Since I’ve never played it, I am totally faking it when it comes to the lore;-)

All I know comes from the Horizon Islands - Armed Assault Wiki, and the Micro Machines Podcast - Episode 22 (Horizon Islands Defense Forces)



Circuit Design and Electronics

Motor Control

I’m using two DC 3V-3.7V Coreless Motor 0408 for the props in the plane. They are nice and small - 4mm x 8mm - with an unusually long 7mm shaft making it easy for direct drive installation.

These motors spin anti-clockwise when powered +ve to red lead. The model props are pitched to spin clockwise - so wire motors in reverse (+ve to black lead).




Mini-gun Simulation

Aside from an impressive visual display, the mini-gun hide the in-flight mounting. It is simply a 255mm Yellow LED Soft Silament / silicon rope DC3V controlled by a 555 timer astable configured to run at 10.213 Hz





The fire/explosion effect on the base is animated with a couple of 5050 LEDs:

  • controlled with an OpAmp-generated triangle wave to give a slow “glow” effect
  • driven via an amplified current mirror for better LED brightness control




Final Protoboard Build

After checking all the electronics, I fitted all the circuits onto a 4x6cm protoboard with micro USB adapter for power. Here’s my plan of the layout with the final build:


Connectors from plane:

wire connection
black ground
red port motor
orange starboard motor
yellow mini-gun

Build Log

Customising the interior with open doors ready to take some heavy metal payload..

build01a build01b

Some micro motors are going in the props.


Motors installed and basic interior completed


Main parts primed


Starting to build up the “original” scheme (that will later be over-painted with khaki)


Preparing the crew and miscellaneous interior fittings

build02a build02b build02c build02d build02e

build03a build03b build03c build03d build03e build03f build03g build03h build03i build03j

build05a build05b build05c

oh shit, tick-tock, better get moving. carry on, unblock, gotta get my build in.

Just sprayed on some HIDF markings on my “field-applied khaki” over the original yellow of this Twin Otter that’s been commandeered for island recon and covert ops. Classified weapons system is still under wraps;-)

Hope to get this completed by the weekend - all the bits are coming together (slowly!)

build06a build06b build06c build06d build06e

First Flight

First flight of the HIDF Twin Otter specops gunship. Based on the Revell 1:72 kit, this has been adapted for the @micromachinespodcast HIDF group build

build07b build07d build07e build07f build07i build07k build07m build07o build07p build07q build07r

HIDF Twin Otter Recon/SpecOps

There’s a backstory here ofc, but I just heard it thru the grapevine. Something like: an ex-Canadian Armed Forces DHC-6 Twin Otter was on charter in the Horizon Islands when the South Pacific Disaster struck. Needing only moderate repairs to get her back in the air, the DHC-6 was commandeered by the Gendarmerie and pressed into service for island reconnaissance and covert operations. The interior was stripped and left with open side hatches to provide maximum payload flexibility - from transporting medical supplies, to extracting a tactical response unit. Although intended for stealthy operations under the radar, port and starboard waist gunner positions can be fitted with a range of equipment, up to and including a wicked mini-gun for when things get a little hot.

About the build: this is the DHC-6 Twin Otter from Revell (04901 in 1:72), modified to take motors for each prop. The mini-gun fire hides the in-flight mounting - 1.5mm annealed florist’s wire from Knorr Prandell. The explosion/flame effect on the base is animated with 5050 LEDs.

The electronics to control the motors, mini-gun effect and explosion are all mounted on a small protoboard. Motors - 555 timer-based PWM circuit for independent variable speed control. Explosion - variable current glow effect driven by OpAmp triangle-wave oscillator. Mini-gun - LED rope driven by 555 timer.

hero1-build07g hero2-build07h hero3-build07n hero4-build07a hero5-build07j hero6-build07l hero7-build07c

Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.