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Project Notes

#599 Kawanishi K5Y1 Tensegrity Stand

Experimenting with tensegrity model mounting, using as a subject the ARII 1:72 Kawanishi K5Y1 赤とんぼ (Willow).

Build

Notes

Was it just me that noticed Tensegrity sculptures become a thing in 2020 all over tiktok and the socials? The concept is nothing new - a structural principle involving isolated components under compression inside a network of continuous tension. In its most drammatic form, it can make structures appear to float:

tensegrity008

This model build started as an idle thought experiment. Could tensgrity principles be used to mount a model plane apparently “in flight”?

Turns out the answer is yes! It is however highly dependent on the aircraft geometry. Besides being an interesting subject, the Kawanishi K5Y1 works well given the fixed landing gear and relatively forward centre of gravity.

The Subject

The K5Y1 is the Imperial Japanese Navy two-seat intermediate trainer version of the Kawanishi/Yokosuka K5Y. It was nicknamed 赤とんぼ / Akatombo / Red Dragonfly and had the allied reporting name of Willow.

I first encountered the plane when I learned from the arawasi blog there is a full size replica in the Nishiki Secret Base Museum.

clip

The Kit

I found the ARII 1:72 Willow kit in the racks of a local hobby store Hobby Point

It is a pretty old kit (1995) molded in brittle orange plastic with quite a bit of flash. Details are not great and fit is so-so. But it is an interesting subject!

kit_unboxing

Paint

Training Scheme

Color Recommended Used
Red H3 Vallejo 70.908 Carmine Red
Flat Black H12 Vallejo 70.950 Black
Orange H14 Vallejo 70.851 Bright Orange
Clear Red H90 Vallejo 70.909 Vermillion
Clear Blue H93 Vallejo 70.839 ultramarine
Steel H18 Vallejo 70.863 Gunmetal Grey
Silver H8 Vallejo 70.997 Silver
Burnt Iron H76 Vallejo 70.863 Gunmetal Grey
Gray H22 Vallejo 70.992 Neutral Grey
Tire Black H77 Vallejo 70.862 Black Grey

Alternative Scheme:

Color Recommended Equivalent
IJN Green H59 70.897 Bronze Green

Pilot

Color Recommended Used
Khaki Green H80 Vallejo 70.924 Russian Unf. WWII
Flesh H44 Vallejo 70.845 Sunny Skin Tone
Mahogany H84 Vallejo 70.846 Mahogany Brown
Red Brown H47 Vallejo 70.984 Flat Brown

Construction

build_01_primed

Pilot features were not molded very clearly. I did my best to give them real faces - seems to work at a distance but not up to close inspection.

build_02_pilots

build_03_fuselage_closed

build_04_painting

A quick 360˚ around the finished model:

build_05_0200 build_05_0230 build_05_0430 build_05_1100

The Tensegrity Stand

This in-progress shot shows the basic tensegrity principle pretty clearly:

  • landing gear hang down from a hard-point
  • with the plane angled down, the centre of gravity is pushed over the landing gear (I was prepared to, but turned out I didn’t need to add any extra weight inside the body for this)
  • a second hard-point is used to tie down the tail to prevent it tipping forward

The result is quite pleasing - the place is slightly “hovering” above the stand. And it has a nice wobble when nudged. Next time I should get some transparent fishing line - the white cotton was the best option I had on hand.

build_06_2

With some mock clouds to hide the stand:

build_07 build_08b

At home on a bookshelf:

build_12a build_12b build_12c

Credits and References

About LEAP#599 scale modelsCraft
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 my personal collection of electronics projects, 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 (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.