protecting igniters

Hi,
I have recently started dipping my own igniters. I have been using
daveyfire or similar low curent electic matche and dipping it in
pyrogen, but realized how fragile the cured pyrogen is.
Does anyone have any easy suggestions of how to protect the pyrogen
from cracking?
I have heard that you can dip them in lacquer but wasnt sure what kind
to buy. I tryed dipping them in slow curring epoxy after the pyrogen
had cured for a few hours. I decided to test them in my back yard using
a 9Vt battery, (I will be using an altimeter to set off the e-matches)
and found that the electric match popped, but the pyrogen remained. I
am 100% sure that the epoxy was what kept the igniters from lighting
because I have used these dipped igniters the same way, but without
them being dipped in epoxy.
Thanks for your help,
Tom Sak
Reply to
TJ
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Dip them the week I'm going to use them. Protect them so the pryrogen does not come in contact with anything. This can be done by putting them in a plastic bag or a paper tube.
THere are other ways I've seen but this is how I do it.
Reply to
Phil Stein
There was a thread here on dipping igniters. Do a search on "Dipping igniters" in your newsreader. The folks here gave absolutely excellent advice. The thread was 4/28/05 One suggestion is not to dip the pyrogen thickly and use an appropriate gauge wire. Be careful in using hand dipped igniters with an altimeter as the 9V battery may not be reliable. I am sure someone will respond to this as I have not progressed to the stage of dual deployment yet. I would be curious to see if the more the experienced rocketeers are using hand dipped igniters for dual deployment. My impression was (and I may be wrong) that they were using commercially available low-current igniters and they were becoming harder to get. I had better luck with a relay ignition system and I think part of my problem was the 30gauge nichrome I was using. Launched yesterday an all of my "newer" igniters worked like a charm.
Kurt Savegnago
Reply to
Kurt
For dual deploy, use the low- current ignitors. Once in a while I see someone playing around with Xmas bulgs or home made ignitors and they have a very high failure rate.
The homemade ignitors are fine for lighting a booster. 30ga nichrome works well. Maybe you had a problem soldering it. To solder it, use acid core flux with solid solder. These are both in the plumbing dept. of the hardware store. After soldering, dip in a baking soda & water solution to get rid of the acid & then rinse with clean water to get rid of the baking soda. After that, dip away.
The 30ga nichrome should work fine
Reply to
Phil Stein
Hi everyone,
I appreciate everyone's quick response to my question; however what I need to find out is how to protect the pyrogen on dipped igniters when installing them into the nozzle. I read that great article that Kurt mentioned which was helpful, but didn't fully answer my question. Like I said I have used these dipped electric matches without being protected with anything, and it successfully lit an airstart motor using a G-Wiz altimeter. When I coated a dipped igniter with epoxy, only the head of the e-match lit but none of the pryrogen.
My only question is how to protect the pyrogen so that it doesn't break off when installing it in the nozzle. This is especially important when I do airstars and clusters which is critical that each igniter is nearly identical in the amount of pyrogen on the head.
I have heard you can coat the pyrogen after it has dried with lacquer. I was thinking of dissolving ping pong balls in acetone to make NC lacquer, and coating my pre-dipped igniter in that mix. I have not made this yet and so I did not know if this was done to increase the ignition heat, protect the pyrogen, or both.
any information that anyone has on protecting the pyrogen on igniters would be greatly appreciated,
Thanks everyone,
Tom Sak
Reply to
TJ
Sorry I missed that part. What size motors are we talking about?
Reply to
Phil Stein
I am using these igniters for I-J range motors.
Reply to
TJ
What pyrogen are you using that is so brittle? I've used two or three brands and none have been so brittle that it breaks off when inserting an igniter into a motor. My igniters bounce around in the range box and the pyrogen does not break off. Some are three years old. (I store then in a plastic tube.)
What type of motor are you using? Single use? Reloadable? Single throat nozzle?
It's often better to use a multiple stage ignition system than a wire with lots of pyrogen. Cesaroni motors are an example. The igniter wire is the first stage. A pellet of something is the next stage, which ignites the propellant. It works. I've worked with 5 motor clusters (core Pro 54 with four Pro 38 outboards) and all ignited immediately. Multiple times. (With video to prove it.) Pyrodex pellets are great for producing simultaneous, instant motor ignition using an undipped Daveyfire N28B or similar igniter. Another option is to paint vertical stripes of pyrogen on the top grains of each motor. If you definitely want positive ignition then research copper thermite.
At one time there was a major problem with Firestar igniters. We thought that a coat of nitrocellulose lacquer would help because the early thought was that there was a moisture problem, but it didn't help because the problem had a different cause. (The wire would burn but the pyrogen would not ignite.) The pyrogens I've used don't need a sealant, and none have been so brittle that they break off while the igniter is being placed in a motor.
Dean
Reply to
Dean
Since you mentioned not using NC lacquer, what are you using for a binder? That sounds like the problem to me. Your binder is too fragile/brittle.
Mike Fisher Binder Design
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Reply to
Binder Design
If you are using 38mm, reloadable AeroTech motors, put a 50 caliber, 30 grain Pyrodex pellet in the top of the top grain. Instant ignition. I've done that many times.
Dean
Reply to
Dean
I don't know current availability status, but the Igniterman kits include (included?) a lacquer that was specifically made for that. (Evidently some kinds of lacquer, such as nitrocellulose, cause the pyrogen to pop off instead of flaring properly... Rob found one that didn't.)
-dave w
Reply to
David Weinshenker
I was using the pyrogen kit from PML. Im not sure what brand it is, but now I know that firefox
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has many more types of pyrogen and at a cheaper price too. The kit continains an oxidizer that you mix with a highly metalic chemical. There is no binder included with the kit, only these two chemicals.
I guess what I'm looking for is a binder to hold the pyrogen together, or another brand of pyrogen that des not have this problem. I have heard the people have used pyromag magnum pyrogen and have had success. If the problem is the pyrogen I'm using, then anyones suggestions on a better pyrogen would be greatly appreciated
Thanks everyone for your help,
Tom Sak
Reply to
TJ
Popular pyrogens sold for rocket motor ignitiers:
Rocketflite's Magnelite
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's Firestar Igniterman Hellfire
According to PML's web site, PML sells Rocketflite's Magnelite. I've used Magnelite and did not have a problem with brittle pyrogen that easily broke off igniters. Did you mix it correctly? Instructions are here:
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Stir before use. Stir every 10 dips or every 5-10 minutes while dipping igniters or the metal powder will settle to the bottom of the bottle.
Dean
Reply to
Dean
It's a pellet of compressed BP. The larger (Pro75) motors also have it, but their igniter is also an e-match attached to a short length of something else - thermalite perhaps? If you search back on RMR a bit there's a great post from Mike Dennett of Cesaroni regarding Pro38 ignition. Apparently the last thing you want to do (and I imagine this applies equally to all motors) is to light them half way up the core with a dipped igniter!
Sometimes there's a brief delay between the pellet burning and the motor coming up to pressure, but usually its pretty much instant. It was suggested that the slower-lighting motors might be older ones that people have been storing, but I don't know if there's anything to support that.
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(be warned, an 11mb file), notice the slight delay. (J330)
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- noticably faster (J285 or J330, can't remember!)
I'm not suggesting its a problem, it just interests me :)
Got any photos/video of your ProXX clusters?
Reply to
Niall Oswald
The Rocketflite / Firestar folks use PlastiDip.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Reply to
Bob Kaplow
Stills and video can be found here under "Media":
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The rocket was built by a group of high school students (with help from mentors). It has flown three times with slightly different Pro38/54 motor combinations. All three times the cluster ignited simultaneously on the pad.
Dean
Reply to
Dean
Your typical igniter kit comes in three parts, metallic fuel mixture, oxidizer, and binder, usually NC lacquer powder that you mix with acetone to dissolve.
First you wet out your metals with the liquid binder, then add oxidizer.
Mike Fisher
Reply to
Binder Design
What motor combinations were they? The combination of SS/Classic is quite interesting, in some of the video clips it looks almost like AT White Lightning.
Reply to
Niall Oswald
If my recollection is correct:
First flight : K660 and four J400SS Second flight: K660 and four J330 Third flight : K660, two J400SS, two J330
Dean
Reply to
Dean
At first I didnt add enough acetone. I had gotten help from one of the members of my rocket club and he added a lot of acetone. I stired it for 5-10 minutes until it was the right consitency. Everyting was normal until it dried. I let it dry about 1-2 hours, and It was very "dusty" .If I touched it with my finger, it would leave some metalic dust behind, and it would cruble when it was inserted into the nozel.
When I mixed it, it came with an oxidizer,which was a white powder and then there was a liquid metalic part. I mixed it as the instructions said, and added the oxidizer a little bit at time and wet it out until all of it was gone, then added the 3mL of acetone. I can get the consistency right, the only problem is that it crumbles when it dries. I did a few ground test before I comited to flight and they all worked perfect. They also worked perfect in my rocket as well, with the exception that one of my clustered motors didnt light, but that was not related to the pyrogen cracking.
It's very frustrating because I am sure that I follwed everything the instructions told me to do, and yet the pyrogen is still very brittle.
Tom Sak
Reply to
TJ

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