How do you make your ejection charges?

[PayLoad]

Nowhere can I find people discussing using glove tips, centrifuge tubes, etc. Everyone talks about using them, how about showing how you make them? Personally I have no luck with centrifuge tubes, but some luck with rubber glove fingertips, I don't know if I am taping them up right or not. Any hints? Suggestions? Step by step with photos for the beginners here?

 

[markg]

Nowhere can I find people discussing using glove tips, centrifuge tubes, etc. Everyone talks about using them, how about showing how you make them? Personally I have no luck with centrifuge tubes, but some luck with rubber glove fingertips, I don't know if I am taping them up right or not. Any hints? Suggestions? Step by step with photos for the beginners here?

Here you go, also the best thread on how to build a fiberglass rocket :

https://www.rocketryforum.com/threa...ss-kit-build-starts.45666/page-10#post-456930

 

[cwbullet]

Ok. You have done it. I will do an article on this while on terminal leave.

 

[Antares JS]

I use hard canisters bolted and/or epoxied to the av bay bulkheads. I just add the ematch and powder, fill up the rest of the canister with dog barf, and seal them with a few layers of masking tape.

 

[cwbullet]

I use hard canisters bolted and/or epoxied to the av bay bulkheads. I just add the ematch and powder, fill up the rest of the canister with dog barf, and seal them with a few layers of masking tape.

do you have photos?

 

[astronwolf]

Here you go, also the best thread on how to build a fiberglass rocket :

https://www.rocketryforum.com/threa...ss-kit-build-starts.45666/page-10#post-456930

He didn't ask "how do I build a fiberglass rocket."

 

[rharshberger]

Ok. You have done it. I will do an article on this while on terminal leave.

"Terminal Leave" from a doctor that sounds bad, of course I do know of what you are actually referring to as I took 30 days when I ETS'd.

 

[OKTurbo]

This video shows the OKTurbo glove tip ejection charge method.

 

[Banzai88]

He didn't ask "how do I build a fiberglass rocket."

The specific link that he provided are the step-by-step instructions in that thread for building glove fingertip charges.

 

[sriegel]

Roughly 1.25" pieces of BT-20 with epoxy layer at one end. Drill hole in epoxy for the e-match lead. Drop in powder, stuff a plug of dog barf in tightly, fold end closed, wrap snuggly with electrical tape going end to end. Taped to end of all thread coming through bulkhead. It's not as elegant a some but it works for me.

 

[Worsaer]

There are many threads with this info. For example:

https://www.rocketryforum.com/threads/black-powder-charge.142926/page-2#post-1767827

 

[Sooner Boomer]

I use 1 1/4" long pieces of BT-5 body tubing. That's long enough to hold over 4 grams of 3F powder (and the ematch). I cut a bunch of tubes to length (I've made a marking guide/sleeve). I cut 1/2" disks from scrap cardboard (cereal box). I push a disk about 1/8" into a tube with a dowel. I glue the disks in place with yellow glue*. When the glue is dry, I add an ematch and the powder charge. I wad up a 1" square of paper towel and tamp it in place with a dowel**, then I glue on the second end disk. When all the glue is dry, I store the charges in a silver static-proof bag used for electronic circuit boards.

*if you're making a bunch of charges, or just prepping the tubes with one end disk, epoxy will work just as well, and sets up faster

**Probably not needed, but I want to make sure all the powder is in contact with the ematch

Tubes, sleeve in blue tape, end disks, dowel


completed charge

 

[JohnCoker]

 

[markg]

He didn't ask "how do I build a fiberglass rocket."

Here you go, also the best thread on how to build a fiberglass rocket :

https://www.rocketryforum.com/threa...ss-kit-build-starts.45666/page-10#post-456930

"Here you go" - this is a link for the information you are requesting.
", also the best thread on how to build a fiberglass rocket :" - in addition to that, this link also has information on another topic that may interest you (or not)

Perhaps you could actually click the link and see what I posted before jumping in to criticize.

cheers

 

[markg]

I use hard canisters bolted and/or epoxied to the av bay bulkheads. I just add the ematch and powder, fill up the rest of the canister with dog barf, and seal them with a few layers of masking tape.

I use this on some of my rockets in combination with glove tip charges. I prep the glove tip charges at home prior to flying. When I prep the rocket for flight I put the glove tip charge into the charge well and cover it in masking tape to keep it in place. This keeps me from having to deal with loose BP at a launch for a rocket I am going to fly multiple times.

Most of my charge wells are 3D printed PETG and no, they do not melt, I haven't had to replace one yet.

cheers - mark

 

[Antares JS]

I also want to note, I have never been comfortable with the idea of glove tips or anything else that is not solidly attached to something inside the rocket. Hard canisters also have the advantage of directing the charge toward whatever you're trying to eject, potentially making your ejection charges more efficient and requiring less powder.

 

[Steve Shannon]

I just use PVC pipe caps glued to the bulkhead of the avionics bay. I put my BP in, lay the match on top, and put a tape lid on top to hold everything in.

 

[loopy]

I use the centrifuge tubes that AT puts the charges in with the reloads. Cut a hole in the bottom, feed the e-match through, tape it in place to seal the hole...load with powder (using the handy markings on the side to know how much), stuff with dog barf to keep it tight against the matchhead, seal with electrical tape. Easy-peasy.

 

[jahall4]

Personally I have no luck with centrifuge tubes?

How so?

 

[PayLoad]

How so?

The seem to fizzle & not go boom

 

[JohnCoker]

The seem to fizzle & not go boom

You should make sure the BP is packed tightly around the ematch head. I fill the remaining space with Estes recovery wadding. (My video shows the full process, among other things.)

Note that I assume we're talking about lowish altitude flights. Above about 30,000 feet, you need to create an airtight seal for the charge or switch to a CO2 ejection system.

 

[Getmore]

I prefer the glove tip method. It's just so simple. Canister type work well but you have to add them to your avbay build. I prefer to just drill a hole and feed the wire through and seal the wires at the bulkhead of the avbay.

 

[cwbullet]

Canister type work well but you have to add them to your avbay build.

It is not exclusively required. I have been collecting options to test so I will do an post and maybe an article for sport rocketry on the topic.

 

[tsmith1315]

I’m currently using ~1/2” cardboard tubes on the bulkheads, with fiberglass sleeves as cartridges. Sleeves are rolled from fiberglass cloth around a brass mandrel, using up leftover epoxy and scrap cloth. Masking tape to seal the ends.

 

[jahall4]

PayLoad said:
The seem to fizzle & not go boom

You should make sure the BP is packed tightly around the ematch head. I fill the remaining space with Estes recovery wadding. (My video shows the full process, among other things.)

Note that I assume we're talking about lowish altitude flights. Above about 30,000 feet, you need to create an airtight seal for the charge or switch to a CO2 ejection system

Exactly, @PayLoad please take what @JohnCoker says as gospel. Under 15K (maybe 20K or higher) centrifuge tubes are the way to go, they are extremely effective containing the charge, getting all the BP to burn.

Currently I pre-make 3 sizes (1.5g, 2.5, and 6). I do, a few things a little differently from John… First, I use hot glue on the outside of the centrifuge tube to secure the ematch. Second, I use a foam earplug to pack the tube. The plug expands after the tube is closed, compressing the charge. Third, I use 2 pieces of electrical tape, 1 tight across the snap top the other around the tube holding the tape across the top, you don’t want the canister to come open! To date I have stored these charged canisters in a rocket for over 6 months, pulled and tested them. I can assure you they don’t “fizzle”.

 

[Banzai88]

PayLoad said:
The seem to fizzle & not go boom

Exactly, @PayLoad please take what @JohnCoker says as gospel. Under 15K (maybe 20K or higher) centrifuge tubes are the way to go, they are extremely effective containing the charge, getting all the BP to burn.

Currently I pre-make 3 sizes (1.5g, 2.5, and 6). I do, a few things a little differently from John… First, I use hot glue on the outside of the centrifuge tube to secure the ematch. Second, I use a foam earplug to pack the tube. The plug expands after the tube is closed, compressing the charge. Third, I use 2 pieces of electrical tape, 1 tight across the snap top the other around the tube holding the tape across the top, you don’t want the canister to come open! To date I have stored these charged canisters in a rocket for over 6 months, pulled and tested them. I can assure you they don’t “fizzle”.

This. Sealing the hole where the wire peneteates with a little dab of hot glue and packing either expanding foam ear plug pieces or dog barf, and then sealing the cap tight is the key. I've stored packed, sealed charges for years, 100% deployment.

 

[SolarYellow]

Currently I pre-make 3 sizes (1.5g, 2.5, and 6).

What size centrifuge tubes do you use for this? All one size?

 

[jahall4]

What size centrifuge tubes do you use for this? All one size?

Those are the tube sizes.

 

[Jim Green]

I use those plastic BP canisters that Aerotech includes in their single use motors. I just poke or drill a hole in the bottom. Thread an ematch through. Seal around the ematch with tape or glue. Pour up to 2 grams of BP in. Fill the remaining space with dog barf. Snap the lid shut. If I need a bigger charge I find larger plastic canisters on Ebay. I have terminal strips on the outside of the electronics bay bulkhead that are wired to the electronics. I dangle the charge down into the airframe. Put in some dog barf. Put in the parachute with a chute protector. Attach the ematch wires to the terminal strip.
This way the charge is underneath the parachute and blows it out of the airframe like it would when using motor ejection.

 

[DragonRocketry]

I have a youtube video on how I make them using 1/4" launch lug material.