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cool deployment picture captured by onboard camera

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Buckeye

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The red thing is a centrifuge vial blowing the apogee charge. (The motor charge blew first, separating the rocket.)

Capture.JPG
 

TangoJuliet

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Cool image capture, but I really don't know what I'm looking at. Do you have an image of this centrifugal vial pre-launch?
 

noffie79

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These. Commonly used for black powder dual deploy charges. ImageUploadedByRocketry Forum1479068348.936530.jpg
 

Lowpuller

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Where can I buy them? I just want a few, 20 or so.....
 

Buckeye

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Some centrifuge vials

1479075900712.jpg
 

Onebadhawk

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Man, is that a cool pic...
What are the chances of catching that moment in time...
Very cool...
Nice harness too,, lol...

Teddy
 

Nathan

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Here's one I got a few years ago. This is the motor ejection charge from an Estes C6-5. . .

 
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ksaves2

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Make sure you restrain the microcentrifuge charges in a cardboard rocket. I've blown out the sides of two rockets when the canister or pieces thereof blew a hole in the tube.
 

Nathan

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Now that is a cool image! What camera and how was it mounted?
That was a low power rocket that I converted to tumble recovery so that I could launch it over my house without it getting stuck in a tree. It separated in the middle and both sections fell without parachute. The 808 keychain camera was mounted on the upper section facing down so it had a view of the ejection charge. The blue thing in the picture is the rubber shock cord which wasn't used and was wrapped in blue painters tape to prevent it from getting hung up if it came down in a tree.

Here is the full video:
[video=youtube;Hue0j4j51ko]https://www.youtube.com/watch?v=Hue0j4j51ko[/video]
 
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nmartin

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Make sure you restrain the microcentrifuge charges in a cardboard rocket. I've blown out the sides of two rockets when the canister or pieces thereof blew a hole in the tube.
Hi. I'm not sure what you mean by restrain. I wrap the microcentrifuge tube with gorilla duct tape. I also pack wadding after the black powder to fill the gap. Do you put anything to hold the cap down besides the clip?
 

manixFan

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Hi. I'm not sure what you mean by restrain. I wrap the microcentrifuge tube with gorilla duct tape. I also pack wadding after the black powder to fill the gap. Do you put anything to hold the cap down besides the clip?
The tube should not be able to move. I always orient any ejection canister up/down with the bottom firmly held against a bulkhead. When the ejection charge goes off don't forget about the 'equal but opposite' reaction of the tube wanting to go in the opposite direction of the hot gases. While it may not weigh much if a tube is sideways in a rocket it can be 'ejected' through the side of the rocket when the charge fires.

And yes, the cap should be held closed to allow the pressure to build so as much powder can burn before the cap blows. I use several wraps of electrical tape.


Tony
 

Buckeye

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Make sure you restrain the microcentrifuge charges in a cardboard rocket. I've blown out the sides of two rockets when the canister or pieces thereof blew a hole in the tube.
I must be doing something wrong. I never blew a vial cap through a body tube or exploded a vial into shrapnel. My rockets are LOC 2.6" and 4" cardboard, which are very thin and wimpy, and they easily withstand 1.0 to 1.5g charges packed firmly. The cap blows off, but the vial remains intact. I tape down the ematch leads to the bulkhead, and orient the vial forward, but it can still flop around somewhat. No problem.

Methinks the BT damage has more to do with overly-aggressive charges.
 

ksaves2

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Hi. I'm not sure what you mean by restrain. I wrap the microcentrifuge tube with gorilla duct tape. I also pack wadding after the black powder to fill the gap. Do you put anything to hold the cap down besides the clip?
No don't restrain the cap. Use dog barf and tape. If you look at some of the instructions of some of the Perfect Flight altimeters, they show the apogee charge "blowing up" from the bottom of the rocket with long lead wires.
If the canister blows at a slight angle, it could come out the side of the rocket if the leads are long. I had that happens twice with main chute charges where I had the lead tails too long and the charges were unrestrained. For the main, restrain the canister to a long bolt through the bulkhead with zipties. Also good idea to use the gorilla tape to keep the canister from blowing apart like you mention.

With fiberglass rockets you don't have to take this extra step. Kurt
 

ksaves2

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I must be doing something wrong. I never blew a vial cap through a body tube or exploded a vial into shrapnel. My rockets are LOC 2.6" and 4" cardboard, which are very thin and wimpy, and they easily withstand 1.0 to 1.5g charges packed firmly. The cap blows off, but the vial remains intact. I tape down the ematch leads to the bulkhead, and orient the vial forward, but it can still flop around somewhat. No problem.

Me thinks the BT damage has more to do with overly-aggressive charges.
I restrained the cap with several layers of tape and didn't wrap the canister. It shrapnel "ized". I don't do that
anymore. I sometimes use a cardboard circle over the BP and put the dog barf on top if there is dead space and
two layers of duct tape. I cut off the cap.

When I blew out the sides, I was using the same amount of powder I had used in the past that I determined was
reasonable and weigh the charge on a decent scale. Man there are economical digital scales out there now for this.

Kurt
 

ascastil

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Just ordered an 808 camera! Cant wait to get some video!
 
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