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cleverfool
11-Feb-07, 08:35
This contraption is called a "Floating arm trebuchet" or FAT (this one is an F2K to be precise). It's a modern optimized variation of the medieval siege trebuchets.

My blender skills are not at all matured, so you may notice a number of things wrong with the animation. Some points of concern:
- The little pieces at the tip of the throwing arm need adjusting
- I need to softbody the sling
- general scene and lighting
- make the wheels actually roll
etc...
(I'll be slowing the animation down later, hard to follow right now I know!)

http://www.organicks.net/models/biomechanics/f2k-animation_draft.avi
http://www.organicks.net/models/biomechanics/f2k-animation2_draft.avi
And the .blend
http://www.organicks.net/models/biomechanics/f2k-anim6.blend

I will be out of town for a week and a half, but when I get home I will fix/add those things.
Any other ideas? Anything make you cringe? Don't be afraid to be harsh :evilgrin:

Thanks in advance

Lord of the Rings Junkie
11-Feb-07, 09:55
At first glance it looks awesome!:) I had a brief stint where I was obsessed with trebuchets, and it looks like you made this one pretty good. The only critiques I have is that the CW looks a little small, and the arm stops swinging rather suddenly after only rebounding after the throw twice or so.

PS I've been trying to find out a way to make a treb simulation using the Blender GE. I had no luck with 2.42a, but maybe I will with the new constraints available in 2.43 rc3.

Haker
11-Feb-07, 13:10
The actual animation has no feeling of weight, try make it "heave" around a bit. Don't be shy of totally working and reworking your animation, you have nothing to lose and knowledge to gain.

Python Angel
11-Feb-07, 13:21
I think the animation is wonderful! :) No real concerns, I think the concerns you already have noted are enough. Additionally, the wheels must adjust to the wood piece they are currently on.

I actually wonder how you did this... I checked out your blend file. I see you split everything in pieces, and so I wonder - how did you animate this properly? You didn't use an armature, did you simply use keyframing and locrot? Because the string seems to be attached to the throwing arm constantly. Any tips you could give? Did you follow a tutorial?

fjornada
11-Feb-07, 14:56
I think the whole idea you got there is quite interesting (I tried once to make a treb animation too, but I gave up...). However, I'll have to agree with Haker about the animation. Before you go on using softbodies, try optimizing the trebuchet's motion. I'd suggest you to pick a simulator, plot arm position against the time, and import the data via python to your animation. I think the only F2K simulator is payed, but the equations of motion should be easily solved numerically. There are surely lots of geeks here pleased to help you with that :-)

Zero Kid
12-Feb-07, 12:46
You may want the whole trebuchet to kick a bit, to give the animation a feeling of momentum.

When you slow the animation down it will give the viewer a feeling of scale, making the whole apparatus seem bigger.

cleverfool
12-Feb-07, 21:41
Thanks for all the advice guys!
I made the animation with keyframes and parenting. First I made the IPO curve for the counterweight, and then I keyframed the arm to line up with it (using N to be more precise). I wanted to track the arm to the counterweight but I couldn't get the 'track to' tool working the way I wanted. The sling is parented to the loop on the end of the arm so it will follow it, then I just gave the sling some rotation of its own.
I sent an email to the guy who invented the F2K trebuchet and he recommended that I remove the A frames (the diagonal supports). He said they weren't necesary but I think it will look pretty precarious without them.
Keep up the great C&Cs!

EDIT: If for some reason I did something in a very smart way, it wont be because I'm good with blender, it most likely seemed like the easiest way :-)

Mike_S
12-Feb-07, 23:51
Thanks for all the advice guys!
I made the animation with keyframes and parenting.

The animation looks pretty good to me, I haven't really looked at the details yet of how you've done everything.

I looked up info on 'trebuchets' when you were discussing how to set this up in the other thread(s), but I didn't find any good examples, so I didn't really understand how it worked. Your model and animation is great though, so now I "get it" :)

Do you have plans in putting this into an animation / scene ?

Have you seen HarkyMan's crowd simulator ("BlenderPeople") ? ...

Add a castle ... some flaming oil pots ..... :)

Mike

Lord of the Rings Junkie
13-Feb-07, 00:12
I looked up info on 'trebuchets' when you were discussing how to set this up in the other thread(s), but I didn't find any good examples, so I didn't really understand how it worked.http://www.trebuchet.com/story.php/fat.html
http://www.vu.union.edu/~stodolan/trebuchet/theory.html (http://www.vu.union.edu/%7Estodolan/trebuchet/theory.html)
http://www.soinc.org/events/stormc/energyrule/EnergyRule.pdf
http://en.wikipedia.org/wiki/Trebuchet

Here's some more links if you're interested.