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How Fast Does A Grape Have To Travel...

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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How Fast Does A Grape Have To Travel...

Unread postAuthor: dilweed » Wed Nov 26, 2008 4:17 pm

how fast does a grape have to travel to explode in mid air.

At 200psi i can get frozen grapes to explode in mid air. How fast is it going?

Also Whenever i fire .25 cal paintballs at high pressure they travel 2 meters then explode in mid air. at lower power i can put .67 cal ones through up to 5 layers at 12 meters.
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Re: How Fast Does A Grape Have To Travel...

Unread postAuthor: MrCrowley » Wed Nov 26, 2008 4:26 pm

dilweed wrote:At 200psi i can get frozen grapes to explode in mid air. How fast is it going?

http://www.thehalls-in-bfe.com/GGDT/lib ... rbit2.html

There is a help section on that site that will help you understand the terminology and the parameters in the program, it's pretty straight forward. Just enter your cannons specifications.

Otherwise, you're going to have to give us a lot more variables then 'a grape explodes in mid air, I used 200psi, how fast is it going?'

You honestly don't believe we could figure anything out from that do you?

dilweed wrote:Also Whenever i fire .25 cal paintballs at high pressure they travel 2 meters then explode in mid air. at lower power i can put .67 cal ones through up to 5 layers at 12 meters.

Awesome, I don't see why they would travel 2m then explode, or how you would even know they travel 2m then explode. If anything they'd explode in the barrel or at the tip of the barrel, not out in the open when they've already decreased speed from when they were first fired inside the barrel.

5 layers of what, exactly?
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Unread postAuthor: LGM » Wed Nov 26, 2008 4:28 pm

Through up to five layers of what?

There's no reason for things "exploding" in mid air. Are you sure it isn't just breaking up in the barrel and the chunks just aren't separating noticeably until several meters out? That would make much more sense.

Edit: Crowley posted first, darnit.
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Unread postAuthor: dilweed » Wed Nov 26, 2008 4:34 pm

sorry 5 layers of cardboard. I can see a blast radius it looks like a semi see through white explosion. I also got hit by a little grape "shrapnel". I got hit in the leg and It left a HUGE BLACK WELT. OH yeah also when i fire paintballs they make a sound like a loud crack. Is this sound associated with a light wieght bullet? When I fire bb's it barely makes a sound, Nothing compared to my .67 cal marble/ cast slug barrel.
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Last edited by dilweed on Wed Nov 26, 2008 4:37 pm, edited 1 time in total.

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Re: How Fast Does A Grape Have To Travel...

Unread postAuthor: Ragnarok » Wed Nov 26, 2008 4:35 pm

dilweed wrote:how fast does a grape have to travel to explode in mid air.

There is no definitive answer. It depends on more than just sheer velocity - acceleration, spin, muzzle blast, etc, etc.
The obvious way to find your answer is to get a chronograph and check, or use GGDT for an estimate.

~~~~~

@Everyone else:
Things can break apart some distance from the muzzle, usually due to muzzle blast or an unsustainable rate of spin.

I've had spuds visibly break apart in the air about 10 to 20 yards from the muzzle, usually because they were spinning wildly or flying erratically.
In one piece one instant, flying in three separate ways the next.

The number of incidences like that have drastically reduced since I fitted the muzzle porting to HEAL, and gave it a new polished (and undented - the original one was off Behemoth, and had taken a slight ding) barrel.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: LGM » Wed Nov 26, 2008 4:36 pm

A grape chunk shot back at you from the direction it was flying? With enough force to leave a welt?
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Unread postAuthor: dilweed » Wed Nov 26, 2008 4:44 pm

Ragnarok- Yes it's a shame i cant machine anything. To scared of drilling holes in the tiny supply of pipe i have. I dont have enough money to buy a chronograph. I have to do spudding secretly because my parents found a wood block with 50 bb's embeded in it, 2 rifled slugs, 3 marbles and 1 dart. Hard to do it when the nosie is compareable to a .22 rifle in suburban london.


LGM- Yes it did. I tried freezing grapes because normal grapes blow up in mid air. Very Very annoying when one finds themselves in a shortage of paintballs.


-With my first spud gun(crappy ball valve one), i shot it at my friends house. I told him not to fire arrows in the air. when i turned around to pick up wadding i heard a bang, and saw a arrow shoot out of sight into the sky.
I came back down after roughly 30-50 seconds and stuck in his shed roof. He also sho his metal garage door with a dart and it went through the door, through his fence behind it. Once we loaded a marble in it and fire at 45 degrees into the ground. it went in, bounced of the gravel a couple of cm in and made a hole in his shed window. (I thought he was smart, but unfortunatley, the evidence presented before you points to the contrary lol!)
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Last edited by dilweed on Wed Nov 26, 2008 4:48 pm, edited 1 time in total.

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Unread postAuthor: Ragnarok » Wed Nov 26, 2008 4:46 pm

dilweed wrote:I also got hit by a little grape "shrapnel". I got hit in the leg and It left a HUGE BLACK WELT.

Sounds odd.. could it have been target shrapnel instead?

OH yeah also when i fire paintballs they make a sound like a loud crack. Is this sound associated with a light wieght bullet?

Spheres, if managing to travel significantly above about 600 fps for long enough, will do this.

600 fps is about the start of the transonic region for a sphere, and any velocity above this will cause supersonic airflow over parts of the surface of the sphere, so you get a miniature supersonic crack, even if the ball itself is not supersonic - and the faster you go, the more noticeable the sound.

It's not really a mark of a lightweight ammo, but one of a sphere of enough weight/velocity (or a combination of the two) to stay fast enough for long enough for the sound to be noticed.
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Unread postAuthor: dilweed » Wed Nov 26, 2008 4:54 pm

It was frozen grape. My trouzer had a wet spot with some grape skin on it. I just remembered something. I cant fire a grape at a target over 150psi because the grapes explode before they reach the target. With my 2nd ball valve gun, i also fired grapes but they didn't explode. Same barrle bore, length, chamber volume etc except the valve. When i fired at low power, i could barely see the grape travel in a slight sideways parabola(cant spell this word) after about 30 meters or so it began to spin in a corckscrew fashion with a radius of around 1.5 meters. Could this be muzzle blast effect the projectiles trajectory etc. And could this happen with a frozen grape traveling about 3 and up times faster?
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Unread postAuthor: Ragnarok » Wed Nov 26, 2008 5:02 pm

dilweed wrote:When i fired at low power, i could barely see the grape travel in a slight sideways parabola(cant spell this word) after about 30 meters or so it began to spin in a corckscrew fashion with a radius of around 1.5 meters.

It could happen, although I'd be surprised to see anything rapid enough and of the radius to be recognised as a corkscrew flight path on a regular basis. Although, that said, I've had things curve so violently in the air that I was surprised they didn't land behind me.

(In fact, I have had something land behind me, but that was a boomerang, and not one I'd fired from a launcher)

And could this happen with a frozen grape traveling about 3 and up times faster?

Yes, and some. As you get faster, the more likely air resistance is going to play havoc. Projectile disintegration is also going to to happen a lot more, both in the air and in the barrel.
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Unread postAuthor: jackssmirkingrevenge » Wed Nov 26, 2008 7:40 pm

An African grape or a European grape?
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Unread postAuthor: Ragnarok » Wed Nov 26, 2008 7:54 pm

Huh? I... I don't know that.

YEEEEEEEEEEEEAARRGGHH!!!

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Unread postAuthor: psycix » Thu Nov 27, 2008 4:15 pm

Is it just me or does the BS-meter pick up some noise in this thread?

Grapes flying in corkscrews and exploding like frag grenades?
Doesnt surprise me that your parents won't allow you spuddin'.
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Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

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