Some house keeping things first. While I’m a Subaru guy, I have to say that I’m extremely impressed with my wife’s S4. Not only is it pushing close to 400 horses, but it easily transports 10′ PVC.

I have found the perfect beverage for catapult building. Try it and you’ll see why.

Completed the throwing arm basket and I’m not happy. Its a bit heavy, not curved well and just overall is suckage. Here’s how it came out:

Decided to scrap the design and go for something a bit more slimline. Think this will work out much better but only testing will tell for sure.

Had a friend ask if the catapult would fit through the double doors. Here’s the proof:

So I’m now completing the project on the patio as I need to work on the upper supports. Could almost reach them from the next level up but decided a ladder would be safer.

One problem I ran into is how to glue the parts 10′ up and still get good connections. I ended up making sure everything properly fit, gave myself some alignment lines, and did the glue work at ground level.

Bit of final assembly work once its daylight and it’ll be time to try a test firing. Neighbors beware!

C

In the process of putting the catapult back together. I’m at a point where nearly every joint is either glued or fastened. The original thought was to bolt the joints that don’t receive glue. Upon checking alignment, my fear was I would end up removing too much material and weaken the structural integrity of the joint. I opted to go for #10 sheet metal screws instead.

I wanted to make sure that pipes were fully inserted prior to applying glue or inserting screws. Since you can’t see the inside of the pipe on many of the joints, I simply marked a 5/8″ depth as a guide.

Had a bit of an assembly line going.

I know it does not look like much progress was made, but I’m back to where I started only all the joints are properly locked in.

Next step is to build the rear 10′ supports as well as the throwing arm. For the basket of the throwing arm, I thought I would use a similar joint to the one I used for the pivot point, only this time I’ll use caps instead of adapters on the sides. Here are the parts:

Next step is to glue the parts together, and then go it at with my table saw to cut out the top.

More to come,

C

Thinking if I show up at my wife’s family gathering with a 10′ catapult that throws fire, that might not be enough to convince them I’m a bit over the edge. With this in mind, I’ll also be building a potato cannon. Usually not all that insane, but I’ve decided to build it out of clear PVC so that I can get a good light show going when its ignited.       

Of course I have to finish the current project first…

Progress goes well. Here’s where we are at:

Since a 10′ catapult will not fit in the workshop, I have to improvise.  That top most crossbar will eventually be 10′ off the ground. For now I’m using shorter side pieces so that it is only 6.5′ above the ground. This will let me continue to work on the catapult inside. I still need to glue some critical joints and bolt up the remaining components (remember I need to be able to tear this thing down to transport it, so the bolted joints will let me break the catapult down into smaller pieces).

Soooo, I need to tear it all down, glue certain joints, then put it all back together to be bolted. I’m numbering the joints to help remind me where all the parts go.

More to come shortly,

C

My wife mentioned that I should consider naming the device. I think I have to agree. She wants to name it “Bob The Catapult” but personally I think any device that will be capable of throwing fire over 500 ft needs to have a female name. Thoughts? Could use some suggestions.

One of the things I had to think through was how to make the pivot point for the throwing arm. Bit of time staring at the shelves in Home Depot did the trick (TIP: Home Depot employees get *really* confused when they ask if they can help you find something and you tell them “catapult parts”).

Here’s what I came up with:

The pivot needs to fit snugly over 2″ PVC but provide a 90 degree adapter to throwing arm. The pivot also needs to rotate freely but without so much slop that it blows itself up. I ended up taking a 3″x3″x2″ T (middle of pic) as well as two 3″ to 2″ adapters (shown on each end of the “T”). I then dremeled out the adapters till the 2″ pipe could slide easily through it. The result is what you see above. I just need to glue the adapters into the “T” and this should work out quite nicely.

Device is getting taller and has more supports added in. I moved the winch to the other side so that the remote controls are easily accessible. I don’t want to be anywhere near this thing the first time I go for maximum thrust.

More later,

C

First let me say I have the coolest wife! I mention building a 10′ catapult to drag up to her family gathering and she does not even bat an eye.

Starting to get the basics laid out. Going to use a 12V winch to load the device. Spring with be 10 lsb/ft bungee cord. If my math is right, this should get the initial escape velocity for small loads (a pound or so) up into the range of 150 MPH. Wahoo!

Here’s the layout of the base structure. The electric winch to load it is in the foreground:

Little more progress and here’s the front side of the unit. That horizontal bar will be a pivot point for the bungee cords as the winch draws them in. Figured I better brace that against the rear month point. Newton’s third law and all of that.

More as it happens,

C

Hey all,

Not security related but wanted to share, so figured I would post this here.

I have two kids in their tween years so I love to leverage the opportunity to do crazy science projects under the guise of “furthering their education”. Posted a bit in the past about the Van Der Graaf generator and the Plasma based speakers we built. Both were cool projects.

My wife’s family has a place up in northern NH which they gather at each August. Its in the middle of no where with an awesome lake out back. Over the years I’ve been dragging up some esoteric weaponry like throwing stars, pistol crossbows and even a blowdart gun. While these were cool, they lacked the massive destructive effect I was looking for.

With this in mind, last year we built and brought up a trebuchet. Here’s a pic from when we were testing it:

It may look small but properly tuned it can throw a golf ball 2/3 the length of a soccer field. With some practice, we got pretty good at hitting a 5′ round target.

We brought the trebuchet out to the family gathering last summer and had a lot of fun with it. Staring at that huge lake behind the property however, we just HAD to try throwing flaming objects. Turns out the treb was not very good at that due to all of the flammable parts. Decided that was something I needed to rectify for this year. Of course as the months ticked by, I also starting thinking that it would be even cooler if I could throw the objects further. With this in mind, I’ve come up with this rough design:

Thinking of using 2″ PVC for a majority of the parts. It will give the structure rigidity, is an easy medium to work with, and most importantly, it will resist burning.

So that’s the plan, we’ll see how this project goes. Stay tuned for the results.

C