The YF-19: Chicken Legs

Overall I’m done with the basic shapes of the plane and I’m starting to figure out internal parts. One of the smaller things was the knees, or rather, the mid-section knees that bend forward when the plane goes into GERWALK. This gives it a very characteristic chicken leg shape. So to be able to make it look sturdy enough, it needs an inner mechanism that bends the entire leg, which you can see here in the drawing from the anime.


Those leg connections need to be made of something that can both support the leg and keep the airflow from the intake to the engine (You’ll soon find out, dear reader, that I’m taking this realism thing TOO SERIOUSLY).

So my best reference was the toy, actually. I used it as a basis to model a bunch of sliding plates that overlap each other, like the finger sections of a medieval armour. I assigned a bone to each one, and then constrained them so each one follows the rotation of the lower leg with a different percentage. So the first one would follow it with a 100% strength, the next one with a 75%, next one with a 50% and so on.

May 28 - Inner knee connection

May 28 – Inner knee connection


While this was technically accurate, I couldn’t help but feel this connection system felt a bit too much like a flexible hose. It didn’t convey the sturdy, hard surface support of the legs, and it didn’t resemble much the toy either. So following a bit of a backdraw action, I erased the mesh and the bones and started again, trying to get closer to this:


May 29 - Redesign of knee connections

May 29 – Redesign of knee connections

With a more sturdy and believable system, I went ahead and started developing a similar solution for the lower knee connection. This would be even trickier, because the legs bend forward for GERWALK but bend backward like a human leg when it goes into Battroid. So the connection needs lo look good in both. I tried many different approaches and ended up using the bliss of Inverse Kinematics to keep the plates together, following the leg.

May 30 - Basic lower knee shape

May 30 – Basic lower knee shape

This part took a big part of push and pull, making sure the mechanics made sense while keeping the overall shape as close to the anime as possible. I added struts, extensions and reshaped the leg a bit to make room for it. the result was closer than I expected which made me very happy!

The toy...

The toy…

... and the CG version of mine

… and the CG version of mine.



With this, I could consider that the GERWALK will make sense once transformed. So I started fixing little things, changing colors here and there to make it more visible, and preparing the next stage: robot mode.

About Eduardo

I'm some dude with a huge love for animation and film. I've been working in TV animation for the past 6 years in New Zealand. I love dragons, pointy metal things that can cut dragons, and flight simulators.
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