SketchUp is excellent for sketching directly in 3D. I've been using it for about 4 years now. But for quick mock-ups you can't go wrong with a pen(cil) and paper.
I might be biased but I think learning to draw proper plans and diagrams helps one's engineering skills.

By the way, take a peek at the new AFD wesite, if you feel like seeing my other projects.
Yes, a good IBL never hurts.

I wanted to surprise everybody by keeping it a secret and building it myself but it's been more than 6 months since its inception and I still haven't found time for the build. So I'm releasing the idea, hoping that someone would find it interesting enough to give it a try.
Hopefully the animation ...

I don't think that would technically be semiautomatic, you'd basically just have 4 cannons. Before the Gatling, Maxim, revolver etc. there were volley guns and even pistols with multiple barrels which were essentially multiple firearms in one package. But we don't call those (semi)automatic, do we ...

If you use the chamber's fundamental, won't you just get big fat standing waves? I would go with Brown noise or some prime frequency in the bass range (would need to experiment a little there). Thankfully an oscillator + amp is easy 'nuff to build. A transducer that can handle the heat is more of an ...

non lethal toys that can kill you

Funniest thing I've heard all day.
(Yes, I'm still watching the forum, if anybody asked )

Since it's a small chamber (around a liter, I guess), I don't think complex calculations will be of any use, since the control system to inject a precise amount of fuel is beyond my scope.
I still have some butane and plenty of Killtox, so I guess the best course of action is to just build the ...

In the old days I used to make small flamethrowers from bug spray cans. Recently it has come to my attention that I could use them as fuel for a combustion or hybrid cannon.
Killtox is 50% Kerosene and 49% LPG (Propane - Butane) and is in fact a lot cheaper and more commonly available than the ...

Yeah, and don't forget pencil and paper

Thanks, aesthetics have always been an important aspect. Since it's been sitting in a corner for about a year, it's quite a good thing, too.

@jaffe: I don't know if I mentioned it in this thread or on the description page or if I just wanted to and it slipped my mind but I did not make the ignitor ...

Sssssmokin'!

Are you going to attach it onto a vehicle? If so, having a compressor that big (leaf blower) with its own power supply is a bad idea.
Guess you know what you need to make it more efficient (confinement, nozzle etc.), so good luck.

Here's another trick: sharpen the ends of the screws (mind the threads). It will act like a funnel for the electrons, accelerating them. Should allow you to use a slightly larger gap.
Though someone here said one doesn't really need sparks longer than a couple mm. I tend to agree, especially for ...

I've used it to play AvP (no problem there), I don't think I've tried CS. Could be a firewall problem. Be sure to add the needed ports (27030-27039 TCP and 1200,27000-27015 UDP) to the allowed list.

Why don't you make an electromagnet like the solenoids to trigger the burst disk? I mean... as long as you're working with electric power, I think a linear motor would be more efficient for linear motion, ya?

This discussion is going nowhere, but for the sake of science...

the primary and secondary circuits were [...] tuned so that they resonated at the same (high) frequency (typically, but not always, between 25 kHz and 2 MHz)

So 2MHz is 2 million Hz.
But what do Tesla coils have to do with the high ...