mini hybrid win!

[JDP12]

Stupid auto correct on itouch...

Yes I meant saboting sorry.

More impressive results, looking good!

[jackssmirkingrevenge]

Nice!!!!!! You should really increase your barrel length, some impressive results may show up

I'm actually close to going all BtB on the barrel and making a suppressor unfortunately as it's 5.5mm I can't go for supersonic airsoft BB shots.

I'm doing a 10x shot in the next 5 minutes will a 2g lead sinker

Good luck ;P

Here's a video of it in action at 10x, in real time with sound and at 420 fps

[youtube][/youtube]

[qwerty]

Ooooooh awsome! Shoot some wax and compare it to other air rifles?

[SpudBlaster15]

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[jackssmirkingrevenge]

Shoot some wax and compare it to other air rifles?

Or even better, I could actually remember to be arsed to buy batteries for my chrony!

Very nice work JSR. Great to see the hybrid revolution alive again.

Cheers, nothing really revolutionary though, this was done with easily obtained materials and there's nothing special about the design. It's not even new to me either, what I thought up almost exactly three years ago is pretty much what I'm playing with today, only this time I actually built it

Now, time for 20x

I want to chrony it at 10x, if I'm impressed by the figures I think for this one I will stop there...

[spudamine]

I like it. Do you know what pressure you're burst disk is going at and are you upping it for higher mixes? I guess there is a limit to how much more you can gain from upping the mix without a correspondingly tougher disk.
It's making me want to go and test my new prototype, rediculous 60 hour epoxy cure time be damned

[jackssmirkingrevenge]

Do you know what pressure you're burst disk is going at and are you upping it for higher mixes? I guess there is a limit to how much more you can gain from upping the mix without a correspondingly tougher disk.

I've used a single layer of photo paper for all tests so far, to be honest I have no idea at what pressure the disk fails - I pressurised it to 450 psi with my shock pump and it held, and on at least three occasions a 6x mix ignited without bursting the disk, so using the same disk I should be able to go to at least 20x easily

It's making me want to go and test my new prototype, rediculous 60 hour epoxy cure time be damned

While it might sound like a case of "Do as I say, not as I do", please wait or at least chuck it into an oven to help it along

[SpudFarm]

using the same disk I should be able to go to at least 20x easily

You should use about three layers at 20x if a 6x mix is on the limit of bursting one layer disks.
Without a proper burst disk you will be dissapointed by the power of higher mixes

[jakethebeast]

yeah i think same with SpudFarm. Too weak disk = baad power

[jackssmirkingrevenge]

I've certainly noticed the relationship with disk failure pressure and power, especially after playing with HGDT.

Just for the record, I have no intention of taking this to 20x, I'm probably hovering around the limit of what the chamber can take and I have no data on what the repeated pressure shock and heating cycles does to the epoxy construction, so best to play it safe.

Tomorrow I'll get my chrony sorted to have some actual velocity data other than does/doesn't penetrate steel sheet , take it to 11x and see if I still have ignition, and compare single and double layer disks at 10x.

I believe power is now at a level where I would consider it worth finishing as project, so first I'll shorten the barrel and make a suppressor, if that goes well I'll fit a proper trigger in a Welrod style grip. I was thinking of the possibility of two piezos side-by-side in order to increase reliability.

More testing tomorrow afternoon, we'll see

[Lockednloaded]

or a nice grill sparker piezo lighter, but that may throw off the look of your gun due to the fact that its probably the same size

[jackssmirkingrevenge]

I'm not convinced that it's worth forking out to get a bigger piezo when I seem to be getting good ignition with units that I pick up for free...

[Heimo]

Say JSR, what is the size of your spark gap in this setup, I am building a smallish hybrid (to be mounted on a stock) that I want to take to 10X and I would like to use piezoelectric ignition to avoid complex electronic systems (hence me asking the size spark gap you used).

EDIT: thanks
good thing I went to the trouble to make the homemade spark plug removable, it would make adjusting the spark gap quite easy

[jackssmirkingrevenge]

Tiny, the electrode is almost touching the schrader - it's less than 0.5mm. Before modification is was around 1mm and would not ignite higher than 6x

[inonickname]

Maybe it's time for some nichrome jack? If you designed it well it should be reusable, would ignite reliably and quickly, and not need a lot of current. A smallish battery would probably do it.