New Northwest Onager

[BobP]

I think that shortly before the demise of the late, lamented CatMess, I posted my plans to build a new onager. Today, it is effectively finished.

Vital Statistics:
Frame length: Six Feet
Frame width: Variable, about 2.4 feet.
Arm length: Six feet from bundle center
Bundle: About 60 feet of 3/8 nylon rope. (Didn't measure, should have.)
Trailer Mounted. (A first for me.)
Secret Weapon: Hydraulic jacks to tighten the bundle!

I actually started this project way back in the spring of 2013, while still recovering from breaking my back and leg in a fall. As soon as I was able, I bought some wood (hobbling into Lowe's on a cane) and started construction. NONE of that is being use this year due to bad wood and construction quality, but I learned a lot. That construction was tagged "mockup only". And I used it as such.
6
This year, I started over. Decided to get a trailer, and did. Assembled it.

Decided to change the concept for the crossmembers to use steel brackets instead of wood. Made the steel brackets and added them to last years crossmembers.

Made a throwing arm. For real, not just a mockup. 2x6 main member with 2x4 "triplers". Looks ok. I hope to make a spare before Snohomish.

Put the crossmembers, frames, and arm onto the trailer. Mockup complete! Didn't look bad.

Got some decent wood and built new frame and cross-members. Much better. I learned a good deal about construction techniques after last year's false start.

Started putting it all together. It takes a while, but it all came together, so today:

FINISHED!!!

Today's work was making some blocks for when the jacks aren't there, a trigger setup, sling lines, and other odds and ends. I shall attempt to attach a picture.

Ok, here's the best I can do for now.

Hope that works!

Nope, It didn't. Try again later.

[KerikM]

Great! So how far does it launch? And how do you prevent this from happening prematurely?
See you in about 10 days...

[BobP]

How far: Don't know. Hoping for a couple of hundred feet.
What direction: Don't know. Hoping for forward.
How do I prevent this from happening prematurely? Make a best guess at tuning.

The machine is completely untested and will remain so until Snohomish. It's an adventure!

[BobP]

Ok, I've uploaded a picture to the galley, let's see if I can link it in here.

[album]http://hurlingforums.com/forum/gallery/image_page.php?album_id=10&image_id=46&display=popup[/album]

The picture is called "Finished", which is of course rather silly. Like all of my catapults, it'll never actually be finished until it's rotting/rusting in pieces.

Edit: I've clearly got to learn how to do pictures. You can find it in the gallery.

Since I'm editing, I'll add that I spent some of today making up additional sling lines, making a simple stand for the trailer tongue, creating a new, more secure, safety; and improving winch function. Like I said, never finished.

[madmattd]

[KerikM]

It might be a good idea to not apprise the people running the event, of your machine's untried state. They might not be real enthusiastic about such an unknown. Make the announcement after it has definitively proven itself functional. You might be able to go there early and do this as practice...If not, can you possibly find a field somewhere to first-time it in [relative] privacy? Yes, I know that a couple of machines have made that transition before an audience, but it wouldn't be my first choice.
Whatever you do, I won't tell if you won't tell.

[BobP]

This is Snohomish, where Squash-O-Fire routinely tosses backward across the road and they had me set up where I was almost trampled by a very large horse. I think my untried machine is pretty benign. That said, I'm going to be pretty cautious about working into the higher power realms. And I'll get there as early as I can to get a couple of shots off before there's much crowd.

Matt: Thanks for the help. I'm not finding the "upload attachment" tab, however.

[madmattd]

[BobP]

Ok, here goes with (hopefully) a torsion bundle.

Ok, preview looks good, hitting "submit". Thanks Matt.

[KerikM]

You might want to bring some extra ropes also, just in case...