Ragnarok wrote:I'd wager that with a good barrel, it's near impossible to result in such a jam.
Good points but this was 4.4mm BBs in a 4.5mm barrel, how else would you explain the bulging if to a high speed BB striking a stationary/low speed one?
Posted: Mon Dec 28, 2009 5:20 pm
by Brian the brain
Eagerly awaiting both the clear vortex video and the Cyclone design Rag speaks of...
Hurry up guys!
Posted: Mon Dec 28, 2009 6:50 pm
by Ragnarok
jackssmirkingrevenge wrote:How else would you explain the bulging if to a high speed BB striking a stationary/low speed one?
Well, it will get worse with a heavier BB - airsoft BBs with their lesser mass and larger area are less likely to collide in the barrel.
Alternatively, perhaps one of your BBs was a hair bigger and got jammed in a relatively narrower piece of barrel.
I used the basic principle of adiabatic heating a while ago to accelerate a saboted paintball to around 300 m/s, then bring it intact to a halt again within a couple of metres.
HEAL was fitted with a decelerator after the muzzle, designed to redirect the muzzle blast into a following adiabatic compressor.
Here, the paintball and sabot were compressing the (already pretty dense) air ahead of them until they came to a complete halt.
I've done similar things with other projectiles - spuds, grapes, anything - providing it's near airtight in the barrel.
As for the why, I wanted to look at the effects of extreme acceleration on these projectiles. Some of the projectiles survived well into hundreds of thousands of G. I'd claim that they're perhaps the highest accelerations recorded by the forum (I think it outstrips even Larda's creations), but someone would only prove me wrong.
Posted: Mon Dec 28, 2009 8:26 pm
by DYI
Ragnarok wrote:As for the why, I wanted to look at the effects of extreme acceleration on these projectiles. Some of the projectiles survived well into hundreds of thousands of G. I'd claim that they're perhaps the highest accelerations recorded by the forum (I think it outstrips even Larda's creations), but someone would only prove me wrong.
Actually, I may have something of a claim on the non-destructive acceleration front - 3/8" ball bearings fired from my ETCG propellant testing device reached 2.4* 10^6 m/s^2 average acceleration, and airsoft rounds fired from my current electrothermal launcher may occasionally surpass 3*10^6 m/s^2 average acceleration. Initial acceleration in the ETG may reach 3*10^7 m/s^2.
Of course, if one wants to get into destructive acceleration...
Well, I fired an airsoft round at a 10mm steel plate with my ETG once.
Posted: Mon Dec 28, 2009 9:18 pm
by Ragnarok
And like I said, someone would prove me wrong.
While I'm reasonably sure that 3 * 10<sup>6</sup> m/s<sup>2</sup> can be pulled out of the set-up that I've got (that's "only" 300 kG), I find it doubtful that I could pull millions of G out of the arrangement, as the device itself is certainly not strong enough to take those forces.
Even at the current accelerations, one part of the decelerator has to be replaced every shot. Trying to get much more out of it would likely be fatal.
Posted: Mon Dec 28, 2009 9:46 pm
by jor2daje
Sorry guys its going to be a little longer on the vortex, I almost finished but cracked the lid beyond repair, so now I have to find a new container and build a new vortex block to fit.
Posted: Mon Dec 28, 2009 10:11 pm
by ramses
pimpmann22 wrote:Wild-card line: Might I suggest Giorgio Moroder - Chase for acquisition of 8:24 of pristine high speed footage?
Proper respect if you know where this theme song comes from, other than Midnight Express of course.
well, the MP3 I found was 8:30, and I don't consider my video pristine, but I am terrible at coming up with soundtracks for videos.
[youtube][/youtube]
EDIT; re-uploaded, quality sucked before
Posted: Tue Dec 29, 2009 2:10 am
by CS
Ramses:
Shell ejection, water shots (milk jugs seem to inhibit full potential), fire, ricochet, clear chambered combustion, electrical discharge, rocket, cards, and lastly the knucks - all cool! Have to say everything was an interesting subject for slow motion.
Cookie: The intro is from Coast to Coast AM, 11 PM to 3AM (Mountain time) on endless AM stations. Can't say I have much use for the AM dial besides this, great for sleepy time.
Everyone:
I would suggest more attention on the entire composition of video elements. Without specific nagging, let me point out the best I've saw thus far:
The red area being in focus, while the blue areas are out of focus. Lighter blue being to far out of focus, darker blue being to close for focus. Depths of the blue areas also provide distinct delineation of the red region.
Natural settings seem like a good choice to make these high speed videos.
The velocity of a lot of projectiles are only captured by a few frames, so debris from a target (slower of course) is another thing I'd ensure. Wood, water, fruit, among other objects are interesting.
Continue the knack guys!
Shell ejection makes me want to live in slow motion.
It is. You can see both flame front propagation as well as the flow to the barrel.
I wonder why it flashes up twice instead of burning in one go. Anyone has an idea about that?
For your convenience, I'll embed it.
[youtube][/youtube]
Posted: Tue Dec 29, 2009 5:53 am
by Insomniac
I've noticed that double-burn phenomena a bit in some of the videos I've filmed of clear chambers, and occasionally it will burn through several times more.
I think it's behaving like a valveless pulsejet, similar to the 'jam jar jet', or 'reynst pot' design.
I'm pretty sure excess fuel is what causes it. Notice that the flame front never reaches the rear of the chamber, possibly due to excess fuel which has not mixed with the air properly.
Posted: Tue Dec 29, 2009 7:35 am
by CpTn_lAw
Thanks pimpmann
Posted: Tue Dec 29, 2009 7:54 am
by Insomniac
After seeing that video of the soda-bottle chambered combustion burning, I decided to do some tests of my own. The chamber is a 1.5L soda bottle, with no barrel or anything else attached. I fueled it as a simple pray'n'spray, with deodorant. I moved the spark to 3 different positions and filmed it in both bright and low light to try and show how the flame front spreads throughout the chamber.
It's important to note that not all the varience in flames was caused by spark location, as the mixture was varying significantly from shot-to-shot. Still made for some pretty interesting footage.
Spark in centre of chamber:
[youtube][/youtube]
[youtube][/youtube]
[youtube][/youtube]
Spark at rear of chamber:
[youtube][/youtube]
[youtube][/youtube]
[youtube][/youtube]
Spark at front of chamber:
Interesting. That series of shots with the bottle chamber changed my opinion of spark gap placement. It seems like the rear generates a much faster flame front for a spray and prey, without a fan. I may pursue a clear advanced combustion, depending on what else I do today. (my sister claimed the good computer, so I can either play with fire, or get spawn killed in MW2. ) choices...
