The Party Popper

[Buntyspudbaby]

Greetings.

The Party Popper, a burst disc hybrid:

50cc chamber, Malleable galvanised iron fittings. The T is 3/4".
3/4" union, unmodified. A rubber washer seals it well, and it hasn't degraded or shifted position at all.
Fuelled using a syringe and a bike pump, the fuel is butane.
Disc material is disposable bbq tray.
Ignition is a bbq piezo mounted in a hardwood grip.

Thanks to all.

[mark.f]

It's neat to see people building more small hybrids, because several years ago, almost nobody could fuel them accurately enough.

A little more information like the pre-ignition pressures you use would be nice, but good job!

[Buntyspudbaby]

It's neat to see people building more small hybrids, because several years ago, almost nobody could fuel them accurately enough.

A little more information like the pre-ignition pressures you use would be nice, but good job!

Hey, thanks Mark!

This is my first hybrid, but thanks to the information I have found here it wasn't too tricky to get working. I did mess around with one a while back, and while I trusted the chamber I didn't know much about it so I left it for the time being. The bike pump is not precise enough but comes close. I've ignited 10x mixes in the party popper, and in the video is a 5x mix. I use a single layer of the bbq tray for 5x and 10x mixes. The spark gap is around 2mm and the wires are epoxied into the end cap, with epoxy into the wire itself to prevent leaks.

Including the pump dead space the volume is 68.5 ml. At a 5x mix, the pre-ignition pressure is 58.8 psi and at a 10x It is 132.2 psi. The single layer disc held 250psi from the pump.

[mark.f]

The spark gap is around 2mm and the wires are epoxied into the end cap, with epoxy into the wire itself to prevent leaks.

I think that's the same problem Novacastrian had with his first hybrid... good catch!

EDIT: the gases leaking around the copper core in the insulation, that is.

[Buntyspudbaby]

EDIT: I had some trouble with this thing, it wasn't igniting mixes. I adjusted the spark gap and it has done the trick but the in the process of going over everything I thought about how to improve it. I will be getting a better gauge for the chamber pressure, and making a spark gap that isn't flexible copper wire.