Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > Building Techniques
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-13-2008, 11:51 PM
moonzero2's Avatar
moonzero2 moonzero2 is offline
B.A.R.
 
Join Date: Sep 2005
Location: Elizabeth, Colorado
Posts: 422
Default ffff Black Powder for Ignition Reliability of Clusters

I have a question,… plus I’m looking for your feedback on the subject.

My goal is to increase my reliability of getting all engines to ignite in my cluster rockets. So I was thinking and an idea came to me is; what if once I install the igniter in the engine, that I then put in a very, very small pinch of ffff black powder, and make sure the black powder gets down in and around the igniter, then push in a small wad in wadding down in on top of the black powder to hold both the black powder and the igniter in place. Also I need to let you know that I make my own igniters with nichrome wire.

First; is this OK to do?
Second; if this is OK, should I use ffff black powder or ffff pyrodex ?

If this is a really dumb idea and is way out of line, please be kind.
__________________
Have a good day
Bob
NAR 77103
Reply With Quote
  #2  
Old 05-14-2008, 07:02 AM
shockwaveriderz shockwaveriderz is offline
rocket dinosaur
 
Join Date: Mar 2005
Location: My Old Kentucky Home
Posts: 1,184
Default

Bob:

1st the legalities:

A person is supposed to only purchase Bp if they are using it for antique fireams; on the other hand, we all know a lot of people pay no attention to that fact:

with that said what you are basicaly describing is a BP igniter. Yes the additon of BP wil enhance the ignitability; you only need a smidgen

other alterntives include blackmatch and quickmatch:

http://www.unitednuclear.com/quickmatch.htm

another alternative is using a spider :

http://www.meatballrocketry.com/spider.htm

another alternative get yourself a pyrogen kit and add a little to the igniter and or "paint" the BP grain

regardless of what ultimately decide to do, a hi amperage battery is always the best idea with clusters; as is a relay launcher

I wouldn't use pyrodex as it has a higher ignition temperature than BP. I'm not familiar with ffff pyrodex?

hth

terry dean
__________________
"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.
Reply With Quote
  #3  
Old 05-14-2008, 07:19 AM
jadebox's Avatar
jadebox jadebox is offline
Roger Smith/JonRocket.com
 
Join Date: Nov 2006
Location: Oviedo, FL
Posts: 1,007
Default

If you're talking about model rocket motors, the only thing you really need to do is make sure you use, as Terry suggests, a high-current launch controller. BP ignites quickly and the igniters are very reliable. If your controller delivers enough amps, all the motors will light.

-- Roger
Reply With Quote
  #4  
Old 05-14-2008, 10:45 AM
moonzero2's Avatar
moonzero2 moonzero2 is offline
B.A.R.
 
Join Date: Sep 2005
Location: Elizabeth, Colorado
Posts: 422
Default

Thanks to both of you for your reply.
Yes, I do use a 12 v relay launcher.
And my reliability is probably 99%.
I'm currently building a Saturn V that will be 5 engine cluster.
I'm just thinking out loud about how I can get a higher reliability in cluster moter ignition.
I'll have to look into a Pyrogen Kit and see how it would help me reach my goal.
Thanks again.
__________________
Have a good day
Bob
NAR 77103
Reply With Quote
  #5  
Old 05-14-2008, 12:37 PM
tbzep's Avatar
tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
Posts: 11,610
Default

Quote:
Originally Posted by moonzero2
Thanks to both of you for your reply.
Yes, I do use a 12 v relay launcher.
And my reliability is probably 99%.
I'm currently building a Saturn V that will be 5 engine cluster.
I'm just thinking out loud about how I can get a higher reliability in cluster moter ignition.
I'll have to look into a Pyrogen Kit and see how it would help me reach my goal.
Thanks again.


From what I've read, pyrogen won't really be any more reliable than nichrome that has been packed against the BP with a bit of wadding (with a good 12v source). It will help keep the nichrome insulated a bit to make sure the heat is all the way to the end of the igniter, so it would aid reliablity in that regard. Another area to address is making sure the iginters are solidly planted and don't get pulled away from the BP.
Reply With Quote
  #6  
Old 05-14-2008, 02:22 PM
heada heada is offline
Mildly Insane
 
Join Date: Oct 2006
Location: Central Indiana
Posts: 83
Default

I think you'll notice that nearly all pyrogen formulas are harder to ignite thanthe BP in BP motors(I don't know of any that are easier but they might exist). If you are clustering APCP motors, you'll want to use a pyrogen dipped igniter as they burn hotter/longer than a conductive primer igniters (First Fire type) but shouldn't be required for BP motors.

You best bet with BP motors in clusters is high amperage battery (car battery sized) and igniters that have the same resistance that are properly installed so that they do not pull loose and are in full contact with the exposed BP of the motor.

-Aaron
Reply With Quote
  #7  
Old 05-14-2008, 09:43 PM
moonzero2's Avatar
moonzero2 moonzero2 is offline
B.A.R.
 
Join Date: Sep 2005
Location: Elizabeth, Colorado
Posts: 422
Default

That is my exact thinking to add the BP after I install the igniter and then the wadding to hold the igniter in place. My thinking is the pinch of ffff BP would provide me some insurance just in case one igniter pulls loose away from contact of the BP of the engine.
__________________
Have a good day
Bob
NAR 77103
Reply With Quote
  #8  
Old 05-14-2008, 11:09 PM
Gus's Avatar
Gus Gus is offline
7/21/61
 
Join Date: Sep 2005
Location: North of Detroit
Posts: 2,223
Default

Last month one of our club members (an engineer by trade) led us in the construction of capacitance discharge launch controllers made from salvaged single use disposable cameras.

The basic concept is that a small battery is used to charge a bank of capacitors which then dump big current instantly when triggered.

This same member had a cluster failure last summer launching off our club's equipment so he went home and built a variant of the capacitor ignitor which he now attaches to his clusters when launching with club equipment. The box is connected to his rocket's ignitor leads and then the club's leads attach to the box. The box is triggered by the club's controller just as if it was an ignitor.

This little box (about the size of an iPod) is powered by a double A battery but delivers enough power that the standard Estes igniters have to be hooked in series (those of you more electrically inclined than me will understand) and they vaporize with a pop when triggered.

Very, very, impressive.
Reply With Quote
  #9  
Old 05-15-2008, 07:25 AM
tbzep's Avatar
tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
Posts: 11,610
Default

I've heard of a few capacitor systems that would vaporize the ignitors so quickly that not enough heat would build up in the propellant to ignite it. I have no idea of the discharge rate or the type of igniters as this was a topic on r.m.r. years ago. One big plus for a capacitor system is that enough juice is dumped that you don't have to worry about varied resistance on igniters. They should all heat up instantly.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 05:11 AM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2024