HPR separation charges

[JamesBenMoore]

Hello, new to the forums so apologies if this is the wrong place to ask. I'm looking to find out how I can go about making a separation charge for my wildman 75 with an eggtimer Quantum. I flew it for my L1 cert just using the motor ejection charge, but this time I would like to separate using the quantum and keep the motor charge as a backup so I can get some experience flying with electronics.

My current understanding is I need something to house a black powder charge and then an Ematch to ignite it via the quantum. I'm not sure where to buy Ematch's or what to house the charge in. Any advice or resources on this would be appreciated. Also any comments on how to do this safely and in what order to connect and power on the everything on would be helpful.

 

[Raythain]

Welcome! This might be more appropriate over in the Recovery subsection, but on to the meat of your question.

Deployment charges need to be contained (tightly) to properly generate enough gas pressure to reliably separate the airframe. People do that in a few ways.
Some people use a “charge well” which is a small container (purpose 3D printed, spent shell casing, PVC pipe cap, etc) and cover it with wadding and tape.
Some people use centrifuge sample containers that they buy in bulk and fill the extra space with wadding.
Others of us (and I include myself here) use what are called “squibs” and Herb has a good write up in my club’s newsletter. Basically filling a glove fingertip and using a zip tie to keep everything contained.

As for making the BP go boom, the standard e-match I’ve seen discussed (and used myself) are MJG FireWire e-matches. Your local vendor might have them, or you can get them from Chris’ Rocket Supplies.

Best advice I have is find the other fliers at your club who do electronic ejection and ask what they use and why. Nothing beats seeing what others are doing and picking their brains about it.

 

[Titan II]

https://www.google.com/search?q=dua...IxNDIzajBqOagCALACAA&sourceid=chrome&ie=UTF-8

 

[SolarYellow]

Since you're in Houston, 10ring.com is where (brick & mortar) I found 4FG black powder. Great little shop.

 

[JamesBenMoore]

Welcome! This might be more appropriate over in the Recovery subsection, but on to the meat of your question.

Deployment charges need to be contained (tightly) to properly generate enough gas pressure to reliably separate the airframe. People do that in a few ways.
Some people use a “charge well” which is a small container (purpose 3D printed, spent shell casing, PVC pipe cap, etc) and cover it with wadding and tape.
Some people use centrifuge sample containers that they buy in bulk and fill the extra space with wadding.
Others of us (and I include myself here) use what are called “squibs” and Herb has a good write up in my club’s newsletter. Basically filling a glove fingertip and using a zip tie to keep everything contained.

As for making the BP go boom, the standard e-match I’ve seen discussed (and used myself) are MJG FireWire e-matches. Your local vendor might have them, or you can get them from Chris’ Rocket Supplies.

Best advice I have is find the other fliers at your club who do electronic ejection and ask what they use and why. Nothing beats seeing what others are doing and picking their brains about it.

Awesome thanks for the advice.

 

[JamesBenMoore]

Since you're in Houston, 10ring.com is where (brick & mortar) I found 4FG black powder. Great little shop.

Thanks. I've never done any reloading or made ejection charges so maybe this is a dumb question, but what does 4FG stand for? Something referring to the quality or size of the grains?

 

[Voyager1]

Here is a good general reference from an Apogee Rocketry newsletter:

https://www.apogeerockets.com/education/downloads/Newsletter596.pdf
Have a look through their other newsletters and technical references. They have a vast number of documents covering all aspects of rocketry.

There are many threads on this forum discussing these topics, too.

 

[John Kemker]

I miss Houston. 10ring, Charlie's, White Wings, Bayou Rifles, Three Brothers Bakery, Cellar Door.

At least they have a What-a-Burger near my house, nowadays.

 

[kramer714]

suggestion... once you pick a way to hold your powder, stick with it. Here is why, each way behaves a little differently, not to say you don't get a 'boom' with different methods, but the amount of pressure can be different. A 1 gram charge in a taped up glove finger (how i do it) may behave differently, than 1 gram in a charge cup. The issues is if you ground test with one method and fly with another you might not like the results.

I had a SLI team i was working with, they did a lot of ground testing using charges I made up with the glove finger tape method. At a launch, they asked someone else to help make up the charges (the high school kids are not allowed to make their own charges for the program), they used the SAME amount of black powder, but a very different way of holding the charge. Charge did go off but the rocket didn't separate. Not a happy ending.

 

[JamesBenMoore]

suggestion... once you pick a way to hold your powder, stick with it. Here is why, each way behaves a little differently, not to say you don't get a 'boom' with different methods, but the amount of pressure can be different. A 1 gram charge in a taped up glove finger (how i do it) may behave differently, than 1 gram in a charge cup. The issues is if you ground test with one method and fly with another you might not like the results.

I had a SLI team i was working with, they did a lot of ground testing using charges I made up with the glove finger tape method. At a launch, they asked someone else to help make up the charges (the high school kids are not allowed to make their own charges for the program), they used the SAME amount of black powder, but a very different way of holding the charge. Charge did go off but the rocket didn't separate. Not a happy ending.

Good to know, I'll make sure to ground test the same method I intend to use in flight