Radial Engine Animation WIP

ZooHead

ZooHead

0
I've been working on an illustration of a 9 cylinder 4 stroke radial engine.
As usual I want to keyframe one object and have everything driven by that.

This is a work in progress, and I just reached the point where I'm actually sure
I can make it work without keyframing anything else but the Crankshaft.

I know this is in the Gallery section but I'll add some instructions, tips, tutorials
and files in case anyone else want to frustrate the heck out of themselves trying this.

All the visible stuff is splines, but I may do a version with polygons.
The first articulating piston rod is just a spline line for now.

Feel free to ask questions, I may have some answers.

radial_animate_02.gif
 
For this spline based system I used Parent Constraint Tags instead of the usual hierarchical arrangement.

seq01.gif


Radial Start outline.jpg
 

Attachments

  • Radial Start jas.zip
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During my search for info on radial engines I initially found images of
master rods, designed with symmetrically positioned wrist pin holes.

Because of the pendulum like motion of the master rod, none of the piston rods align with
the center of the cylinder when at top dead center, with the exception of the master rod...

369lot501.jpg


image009.jpg
 
Here's an illustration showing the system at 40˚ rotation, this is top dead center for cylinder 2.

You can see the piston rod is not in line with the cylinder.

Angle at TDC.jpg
 
Here's the system at 80˚ rotation.

This is a 4 stroke radial engine. So if cylinder 1 is now in it's power stroke,
the next one to fire is cylinder 3 which is at full compression TDC.

If cylinder 3 fires at this moment, doesn't it look
like it would be pushing the engine backwards?

Angle at TDC 02.jpg
 
I have a hunch the difference in master rod design may be for a two stroke version, but it's only a guess.

Regardless of which design is used for the master rod, the animation still works fine.

A nine cylinder engine is driven by 9 cylinders, but even if we could drive
the animation from them, why keyframe 9 things when you can keyframe 1.

For this setup I keyed the crankshaft's Y axis which is also the Heading axis (remember this for later).

I set the Frames Per Second to 36 so I every eight frames would fall on 40˚ increments.

Object Crank1's pivot point should be at world center.
•Key frame 1 at zero rotation
•Move timeline forward
•Change rotation value to 360˚
•Keyframe again
 
One problem with splines, you can't snap to the center of one like you can with polygons.

So for ease of snapping I placed polygons at all pivot points.
I also placed circle splines simply for graphic effect.

Crank Pivots.jpg
 
I thought I would share this video of what may be the smallest radial engine in the world.

"It´s built by José Manuel Hermo Barreiro "Patelo" and dedicated to his sons.
Pieces=398,Screws=289,Hours of work=1810."

 
Now it's time to add the first Parent Constraint Tag to make Master1 follow Crank1.

Before you assign a Target in the Tag, make sure the
objects are proper position and Maintain is checked.

Now we have this.

crank_and_master1.gif
 
To make Master1 point towards Piston1, add a Target Tag and target Piston1.

Here's where making objects rotate around the Y axis pays off.
Remember the Y axis is also the Heading axis,
so you want to check- Adjust just heading.

target_piston1.gif
 
Now to make the piston follow the end of the master rod I used another Parent Constraint Tag.

For the target I copied the circle spline from Piston1 to Master1 like this.

Wrist center.jpg
 
Amazing what I can learn on this forum.
Thank you @ZooHead for taking the time and effort to share this.

The rotary engine is quite a clever design.
 
To make the next cylinder position, put all the objects in a folder and copy it.

We don't need the new copy of Crank1 so delete it and turn off all Tags.

Then delete all objects under the new Master1
except the center snap and circle.

Then change the name of Master1 to Slave2.
I would also rename any other new objects with a unique name.

position2.gif
 
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