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Most Reliable Way To Ignite Clustered BP Engines?

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Micromeister

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If you really want to know how to build and launch Clustered BP motors (up to 12 motor cluster) then I strongly suggest a visit to www.narhams.org. Look at the left hand menu for the Library section in the library you'll find Tech-Tips. Tech-Tip 006 Clustering BP motors has recently been updated.
This Tech-Tip will take you through the steps that must be done to reliably ignite BP clustered motors.

OBTW: Clip Whips... No matter how well made, are ONLY an extension of whatever electrical system to which they are attached. Clip-Whips by themselfs are NOT the solution to reliable cluster ignition. They help but if the Launch control system is weak or under powered there is no way a clip whip will help.

Relaible cluster ignition require 3 complete and systematic steps as outlined in my Tech-Tip. Relay Ignition is not A way to ignite Clustered BP motors it is the ONLY Reliable way. This requires moving the Battery Power supply from the controller side of the circuit to the Launch Pad. As close as possible, directly under the Pad is just fine.

Clusters Pg-3-sm_LiftOffs 3,4,&5 motor Clusters &SatV_90-98.jpg


687Lp01d2_65th B-Day Close 4 D12 Cluster Roaring Liftoff 1st Flight_11-16-13.jpg


MM 404Lp02f_Conestoga-1620_on Recovery all Up complete success_11-15-14.JPG
 
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kc9rod

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I am trying launch a 3 clustered rocket for my NARTREK silver.I am thinking of using a flashbulb. for fuse wicks I am thinking of using thread diped in pyro starter used to make ignighters. Any thoughts or Ideas?
 

blackjack2564

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If U ar talking simple bp motors just use electric match. Tape into or on nozzle, I have lit 9 C motors that way. A-B-C D & F all work great.

Low current so any controller will light, but watch out, some the continuity test may fire.

It would be helpful to TELL us what motors u want to lite.


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kc9rod

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Forr my Nartrek I was Goring to use 3 A8-3 un a reproduction of an Estes K6 Astrorn Ranger
 

kc9rod

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If U ar talking simple bp motors just use electric match. Tape into or on nozzle, I have lit 9 C motors that way. A-B-C D & F all work great.

Low current so any controller will light, but watch out, some the continuity test may fire.

It would be helpful to TELL us what motors u want to lite.


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For my Nartrek I was Goring to use 3 A8-3 un a reproduction of an Estes K6 Astrorn Ranger
 

Mike Helm

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Two important stories about flash-bulbs...
1) NEVER attempt to cut the bulbs out of a Magic Cube. I made this mistake once. I don't know which sort of witchery they engineered into those but they fire when you cut the wire. I guess that's why they were 'magic' and those old cameras didn't require a battery. Cutting the bulb free temporarily blinded me and burned the crap out of my finger tips with the light and heat of a thousand suns.
2) Recently I found a zip-loc baggie of flash-bulbs in my old range box. Like a fiend I held it up to inventory my new-found treasure. I rolled the bag between the palms of my hands to flatten them out for counting. Just that simple act generated enough static to set off a chain-reaction! These were the regular flash bulbs that we all use to use regularly. So for the second time I was bit by the flash-bulb.
The moral of the story is; be very careful with flash-bulbs and treat them with great respect. They can be very reliable when used correctly. Back in the day we were using them for igniting clusters, staging and deployment. We could use capacitors to fire them (which were much lighter than batteries). Shrink tubing them to a length of thermolite in a teflon tube made one hell of a high power igniter which was really fast for staging. I always made these with a loop of wire which remained continuous until on the pad when the loop would be cut and stripped. This seemed like the safest way to prevent an accidental firing.
On a side note; at LDRS X out in Hertsel, CO a thunderstorm blew in on us with a full range ready to launch. The range volunteers went out and laid all the rockets down so they wouldn't blow over in the wind but for some reason the pointed the rockets at the crowd. It scared the crap out of me thinking that static could fire any number of the rockets out there. None of them fired but it was discussed that night at the meeting.
 

caveduck

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This is a revived thread but I want to emphasize a caution that Jim mentioned about AG1 flashbulbs. The no-fire current is VERY low, IIRC somewhere in the 20-30 mA range, so low that even an LED may run enough current thru the flashbulb to fire it. Like Mike said above, they can be set off by static as well. Back in the day you had to be very careful that your launch system was continuity-safe for such low-current ignitors, or had a continuity test suppression switch. If I remember right, unintended flashbulb launches were so common for a while that there was discussion in the NAR about banning the method.

Fast-forward to today - flashbulbs have not been much used in a long time since Thermalite became unavailable, and many launch systems nowadays are no longer designed to be flashbulb-safe. I've not seen a continuity-suppression switch on a launch controller in a very long time. I'd advise extreme caution and pre-testing if you go that route. E-matches are much safer in that regard with their no-fire current of ~250 mA.

There is one more method that competition scale people do when not getting all motors lit is penalized in your score. It's a variant of the flashpan called a "spider" where the flashpan has a lid with brass tubes positioned to directly guide burning powder particles into the nozzle of each motor. Pyrodex is the powder of choice. It's a lot of trouble because the spider has to be made for the exact geometry of the motors in the rocket, but spiders are supposed to be almost infallible.
 

kc9rod

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This is a revived thread but I want to emphasize a caution that Jim mentioned about AG1 flashbulbs. The no-fire current is VERY low, IIRC somewhere in the 20-30 mA range, so low that even an LED may run enough current thru the flashbulb to fire it. Like Mike said above, they can be set off by static as well. Back in the day you had to be very careful that your launch system was continuity-safe for such low-current ignitors, or had a continuity test suppression switch. If I remember right, unintended flashbulb launches were so common for a while that there was discussion in the NAR about banning the method.

Fast-forward to today - flashbulbs have not been much used in a long time since Thermalite became unavailable, and many launch systems nowadays are no longer designed to be flashbulb-safe. I've not seen a continuity-suppression switch on a launch controller in a very long time. I'd advise extreme caution and pre-testing if you go that route. E-matches are much safer in that regard with their no-fire current of ~250 mA.

There is one more method that competition scale people do when not getting all motors lit is penalized in your score. It's a variant of the flashpan called a "spider" where the flashpan has a lid with brass tubes positioned to directly guide burning powder particles into the nozzle of each motor. Pyrodex is the powder of choice. It's a lot of trouble because the spider has to be made for the exact geometry of the motors in the rocket, but spiders are supposed to be almost infallible.
 

kc9rod

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No penalties, No contest just trying to get my NARTREK silver level just need one flight with all three firing.
 

caveduck

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Easiest route for that is 3 e-matches or 3 Estes starters with a slight bit of BP. Non-enhanced Estes starters will noticeably increase the chances of not getting all 3 lit; it might take a couple of tries though.
 

kc9rod

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Easiest route for that is 3 e-matches or 3 Estes starters with a slight bit of BP. Non-enhanced Estes starters will noticeably increase the chances of not getting all 3 lit; it might take a couple of tries though.
With a bit f BP??? Keep in mind I'm a born again rocketeer. I flew in the 70's and 80's and just getting back into it
 

BABAR

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Whatever you use for an igniter, make sure you have a 12 volt source.
 

Back_at_it

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I have a cloned Ranger that uses 3x18mm motors. I built it specifically to use up the rather large number of A8-3 motors I had acquired over the years. As others have said, Today's Estes igniters are not the best even for single motor launches. After running into issues with failed igniters I started reading through other peoples suggestions and found someone said to use Testors Silver model paint. It just some happens that I had a bottle laying around.

I took about 10 igniters and dripped them in the silver paint and let it dry. It did take a couple of days to fully cure but once dry I did a test and flame produced was many times greater than the stock igniter. In the field, every igniter worked flawlessly where before I was getting about 1 in 3 failures. Since that first test I have dipped every igniter in that same bottle of Silver paint and I've only had 3 failures in over 300 flights.

Now that brings me back to the clusters. Two of the failures were clusters where only 2 of the 3 motors fired. Thankfully the rocket flew on 2 motors and survived. Looking at the igniters afterwards it was clear that all three burned. I couldn't tell if this was an igniter or timing issue. I suspected that the rocket was leaving the pad before the last igniter lit but couldn't prove it.

To correct the issue I tried something simple. Since I was in WI anyway, I stopped at one of those off the highway fireworks places and picked up a pack of firecrackers. I got home and unrolled the firecrackers and emptied the powder into a plastic container. On my next cluster flight I inserted the igniter into the motor, placed a tiny bit of that powder into the nozzle and inserted the plastic plug. Since moving to this method I have had zero failures on clusters. I feel comfortable doing this as we use to do something similar back in the day with ground up match heads.

I have considers mixing a small amount of the powder into a small amount of the silver paint and dipping the igniters into that but I haven't had a chance to try it yet. Might need to do a batch this weekend and see how it goes.
 

cbwho

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Maybe dip into the silver paint then dip into black powder, then dry...
?
 

kc9rod

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Successful launch!!! took 3 tries on two different days got a launch with all 3 fireing. used plain Estes igniters (got lucky) I do have a question My club president says the flash bulb with a fast cannon fuse is illegal but I cant find anything prohibiting it.
 

kc9rod

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It say it must be electrically ignited so lighting a fuse with a match is out but nothing specifically about fuses.
 

kc9rod

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  1. Ignition System. I will launch my rockets with an electrical launch system and electrical motor igniters. My launch system will have a safety interlock in series with the launch switch, and will use a launch switch that returns to the “off” position when released.
 

kc9rod

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  1. Ignition System. I will launch my rockets with an electrical launch system and electrical motor igniters. My launch system will have a safety interlock in series with the launch switch, and will use a launch switch that returns to the “off” position when released.
It is actually item 3 in the NAR safety code it changed it when I copied and pasted it.
 

Rocketjunkie

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I thought NAR didn't allow fuses?
I use them when the central motor will give a safe flight. The fuses light the outboards from the central motor. You can also tape another motor starter to the fuse for electrical ignition of that motor. Another thing that works is taping an e-match to the nozzle as far as it will go in. Also, for BP motors, make sure there is no clay covering the BP. If you see ANY clay where there should be black BP, scrape it out.
 

JoePfeiffer

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With a bit f BP??? Keep in mind I'm a born again rocketeer. I flew in the 70's and 80's and just getting back into it
As cbwho said, what he's talking about is putting something that burns better on the tip of the igniter. One option, as he says, is dip in some paint (or glue or something) and then in black powder. Another is dip in a nitrocellulose based fingernail polish.
 

JoePfeiffer

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Something that has helped me a lot has been to have a "whip" made up of a switch box and several sets of fairly long igniter wires. I'm able to turn on the switches one at a time to make sure I've got continuity on all of them; then the box is actually mounted higher than the pad so the wires can ride up with the rocket. This way if I have a very slightly late ignition three's still a chance.
 

Joekeyo

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Back in the 1970s I used to launch 3- and 4- motor clusters using only bare-wire nichrome igniters, with a 12V car-battery power source.
I agree. These days, I have also had many 2 and 3 engine clusters work pretty reliability on the current Estes igniter. The igniter has to touch the propellant and the battery has to have enough juice. This is model rocket science facts. No fancy igniter or launch system will work if you do not abide by these simple rules.
So...Make sure your igniter is pushed all the way in - holding the rocket upside down can often facilitate this. Relax and enjoy your flight.
 

JoePfeiffer

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Chances are if your launch system is electric match safe, it's flashbulb safe as well. But check in advance.
It's my understanding modern e-matches require much more current to ignite than the old ones, specifically as a safety measure.
 

JoePfeiffer

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Successful launch!!! took 3 tries on two different days got a launch with all 3 fireing. used plain Estes igniters (got lucky) I do have a question My club president says the flash bulb with a fast cannon fuse is illegal but I cant find anything prohibiting it.
While there's nothing in the safety code prohibiting flash bulbs (it doesn't get into that level of detail) I can easily imagine a club banning them on safety grounds (and they should). Starting a short fuse electrically (using an igniter or something) ought to be fine.
 
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