SpudFiles

I'm proud to announce that my never-before-tried metering system works - flawlessly. I don't know for sure, but most new hybrids don't fire within 50 ms of the first time you ever press the trigger.

I guess a lot of people wouldn't classify this as "small scale testing", but it's really quite miniscule compared to the second testbed design that will follow.

The specs:
Chamber
Volume: 2584 cc (exactly)
Dimensions: 4.026" x 10", plus 6" or so of 2" pipe leading to the union
Material: Schedule 40 welded steel pipe

Valve
2" burst disk (what else )

Meter
Made of SCH 40 steel pipe, mostly 1/4". Currently has 6 ports: oxygen, fuel, air, 0-300 psig grade 1A glycerin filled gauge, 0-15 psig grade 1A glycerin filled gauge, and output.

Safeties
Safety ball valves on both oxidiser and fuel inlets, meter can be detached via hydraulic quick connects before firing, 2000psi rated carbon steel ball valve isolating meter and quick connects from chamber, on/off switch on stungun power supply.

I was going to use air for the initial testing, but I accidentally vaporised one of my brass hose barbs with a burning muffin (don't ask ). The air hose needs 2 barbs to attach to the chamber, and the oxygen hose only needs one. This made the oxidiser decision a very simple one to make.

And because I know how little words mean on the internet, here's the pics and vids:



The whole thing, assembled and ready to fire



Chamber detail. The front plate is 1/2" steel, the back plate is 1.75".



Meter detail. The higher gauge is the 0-15 psig one.



Used burst disks. All 32 layers of aluminum foil.

And the best part of all, the videos. I didn't feel like editing them, so they're shown in their full form, complete with worried parents

http://www.vimeo.com/911462
http://www.vimeo.com/911453

The second one's at night, and shows the muzzle flash quite well.

very, very ,vey nice, good job on the welding too

Sweet, DYI.
I look forward to seeing more of it.

OH yeah baby!!! Now THAT blast was man's man's blast... even came across on the cam recording...normally wimpy little snap shots get recorded.

I love your concerned mom coming out there.

Woah that was epic. Nice muzzle flash to.

lol @ your mum comming out.

Very nice indeed DYI!
The fact that your mom came out tells me that the sound is one hell of a cannon blast!

Very nice. Nice and big, good stuff

what exaclty is your new metering system?

im constructing a hybrid this summer

Nice... damn shame about the burning muffin though - because I want a chocolate one now (preferably not burning, but beggars can't be choosers)

i like your mom at the end of the video...

"oh my GOD thats loud!!!" lol.

My "new" metering system simply measures the chamber pressure. The simplest system, really, but the expensive gauges have deterred others from building it. In my opinion, the shear ease of use and modular capabilities it allows are more than worth the extra $60 or so for high accuracy gauges.

I'm going to try to rebuild the stand I wrecked in the best shot comp and do some damage shots at the range during the week. Although it sounds quiet in the video, it is actually alarmingly loud (even for me) at 3x, loud enough that I'm worried about even my very tolerant neighbours being pissed off by it.

My current meter system allows up to 4x oxy/fuel measured on the 0-15 psig gauge, and up to 20x air/fuel by using both gauges. If I have a sudden moment of bravery, I might try 10x oxy/fuel sometime in the coming week. The use of the 0 - 300 gauge will reduce accuracy, and I don't know if it'll fire. If you don't hear from me again, you'll know what happened

DYI wrote:If you don't hear from me again, you'll know what happened

Ok, I'll be on the lookout for more earthquake reports then...
(Yes, I know it's the same joke Fnord used earlier, go away.)

Thats just a normal hardware store union rated to 150psi isnt it
Have fun with 10x, esspecially with that union, and that barrel

Well aside from it being one of the most dangerous launchers I have ever seen(this is assuming 10x)its pretty good.
Aint pretty but it sure seems to get the job done

Thats just a normal hardware store union rated to 150psi isnt it
Have fun with 10x, esspecially with that union, and that barrel

Well aside from it being one of the most dangerous launchers I have ever witnessed(this is assuming 10x)its pretty good.
Aint pretty but it sure seems to get the job done

Yeah, it's just a normal hardware store union. Keep in mind that the fittings used on _Fnord's 11x test hybrid were all 150 psi rated malleable iron as well. Everything else on the chamber has a burst pressure of over 2000 psi, and a union failure isn't as catastrophic as something like the backplate failing.

And I'll never actually load anything into the barrel at over 3x. It functions mainly as a sound suppressor (although from the videos you can probably tell that it doesn't do a very good job of it). Remember that this is only a prototype to test the concept, it isn't intended as a fully operational launcher. Remote ignition will always be used, reducing the required safety margins.

DYI wrote:Keep in mind that the fittings used on _Fnord's 11x test hybrid were all 150 psi rated malleable iron as well.

Yes but that doesnt mean that it is safe to do
it survived once, who knows if it will survive the second test

DYI wrote:Remember that this is only a prototype to test the concept

Practice for [redacted] huh

DYI wrote:Remote ignition will always be used, reducing the required safety margins.

good gald to hear that