Cluster Launch Power

[delta22]

I plan to build a battery+relay electrical launch system to boost the effective delivered current and voltage to fire big clusters. This would be a relay box triggered by the club launch system.

Looking for input on design.

When I was firing clusters of 8 or less engines, was achieving about 99% success rate igniting engines with club launch systems.

Even using creative methods with ematches to reduce total current, the 8 flights I have attempted with 11 to 30 motors have had much lower success rate. Details at www.bpasa.com.

Voltage sag due to 16 awg launch leads, connectors, and anything less than a very strong battery becomes very significant. While most ematches still seem to fire, some are delayed until the rocket has pulled away from the pad.

The relay+battery system needs to be able to deliver very high current bursts without major voltage sag. Some of the flights I have done have attempted to draw 60 to 70 amps from a 12V system.

Components I am considering:
> 200A automotive relay
> 8 awg leads
> Lipo battery pack: 14.8V (4 cell) 5Ah (40C continuous, 50C for 10 second bursts)

Proposed battery:
http://www.unitedhobbies.com/hobbyking/store/uh_viewItem.asp?idProduct=10307&Product_Name=Turnigy_5000mAh_4S_40C_Lipo_Pack

Questions:

> 200A automotive relay: One reference (at rocketflite.com) advises using a relay with a clamping diode to dampen the voltage created by the relay coil when it is deactivated. If I only trigger my relay box with the club's relay launch system, I would not expect this to be an issue? I also assume that if I did use a relay with a clamping diode, that I would have to determine the polarity of the club's launch leads each time I use them? and would prefer not to do this.

> Lipo battery: Rated for 200A continuous (5Ah x 40C) it should be able to give me all the current I'll ever need in a 1.3 lb battery. With 14.8V at no load, using extremely heavy gauge leads (jumper cable wire) I would expect to put 12 or 13V into the rocket's ignition setup even for very big clusters.

> Suggestions about the battery? Relay? Anything else?

[Rex R]

you had better put a fuse/circut breaker between your pack and the relay just in case you get a dead short(I've seen 8ga wire go POOF when someone shorted a pack). 2) what sort of temps will present at your launch? if you expect to see temps below 75F then I would highly reccomend getting 2(or more) 14.8v* (4s) and run them in parallel, lipos don't like running at max rated output when below 75F(they tend to 'bloat')
*a 14.8v(4s)pack has a fully charged voltage of 16.8v...I would suggest a pair of 3s packs in parallel if your components can't handle 16v.
rex

[SCE to AUX]

> 200A automotive relay: One reference (at rocketflite.com) advises using a relay with a clamping diode to dampen the voltage created by the relay coil when it is deactivated. If I only trigger my relay box with the club's relay launch system, I would not expect this to be an issue? I also assume that if I did use a relay with a clamping diode, that I would have to determine the polarity of the club's launch leads each time I use them? and would prefer not to do this.

The damping diode is a VERY good idea if your club launch system incorporates any solid-state electronics. The high voltage spike generated by a large DC relay coil can easily wipe out semiconductor devices like transistors or IC chips.

If your club launch controller is just a bunch of switches and relays, you are probably OK leaving the diode out. Installing one WILL require you to determine proper polarity for the control signal.





> Lipo battery: Rated for 200A continuous (5Ah x 40C) it should be able to give me all the current I'll ever need in a 1.3 lb battery. With 14.8V at no load, using extremely heavy gauge leads (jumper cable wire) I would expect to put 12 or 13V into the rocket's ignition setup even for very big clusters.


I personally avoid using LiPo batteries in applications where the weight/size constraints don't call for them. They can be finicky to charge properly, and they have a tendency to fail somewhat spectacularly (fire/explosion) if abused. Good old lead/acid gel-cells are really the sweet spot for this type of application. Cheap, readily available, easy to charge, and they can source plenty of current. Suitable ones are available at big box home centers, as replacements for alarm panels and emergency lights.

[delta22]

Thanks for the quick input.


you had better put a fuse/circut breaker between your pack and the relay just in case you get a dead short(I've seen 8ga wire go POOF when someone shorted a pack). 2) what sort of temps will present at your launch? if you expect to see temps below 75F then I would highly reccomend getting 2(or more) 14.8v* (4s) and run them in parallel, lipos don't like running at max rated output when below 75F(they tend to 'bloat')
*a 14.8v(4s)pack has a fully charged voltage of 16.8v...I would suggest a pair of 3s packs in parallel if your components can't handle 16v.
rex

I was on the fence about using a fuse. Many launch systems don't use them to remove one failure mode, but shorting is a risk. I'll add one.

With regard to current loading, I probably won't load system more than 100A for 1-2 seconds at a time, maybe 10-20 times per year.


The damping diode is a VERY good idea if your club launch system incorporates any solid-state electronics. The high voltage spike generated by a large DC relay coil can easily wipe out semiconductor devices like transistors or IC chips.

If your club launch controller is just a bunch of switches and relays, you are probably OK leaving the diode out. Installing one WILL require you to determine proper polarity for the control signal.

I personally avoid using LiPo batteries in applications where the weight/size constraints don't call for them. They can be finicky to charge properly, and they have a tendency to fail somewhat spectacularly (fire/explosion) if abused. Good old lead/acid gel-cells are really the sweet spot for this type of application. Cheap, readily available, easy to charge, and they can source plenty of current. Suitable ones are available at big box home centers, as replacements for alarm panels and emergency lights.

Will the collapsing magnetic field create a voltage spike of more than the original 14 or so volts?

I suppose I could use a much smaller relay to trigger the large relay. Club system triggers my smaller relay, smaller relay closes circuit with known polarity on big relay that has clamping diode.

This would allow the club launch leads to be attached with either polarity, but still protect club system from sizable voltage spike.

I do understand that lipo's are more difficult to handle than lead acid batteries. The plusses with lipo's are 10-15 lbs less weight for the cluster box, and 2-4 more volts under load. As long as it works, those are pretty big advantages.

[Rex R]

lipos also require chargers that are setup to charge lipos along with a balancer to ensure that ALL the cells have the same voltage. also lipos are not overly robust mechanicaly. while it has been some time since I've heard of a catastrophic failure...they can happen, add to your launch supplies a bucket of dry sand in case of fire(most fire extiguisers are not designed for lipo fires).

[SCE to AUX]

Will the collapsing magnetic field create a voltage spike of more than the original 14 or so volts?

Absolutely. The amplitude of the spike depends on coil inductance and switching speed, but can easily measure hundreds of volts.


I suppose I could use a much smaller relay to trigger the large relay. Club system triggers my smaller relay, smaller relay closes circuit with known polarity on big relay that has clamping diode.

That should work well.

[Rex R]

personally if I were to go to the trouble of making an electrically isolated launch circut...methinks a 24v setup would be less work. half the amps means you can use lighter wire, ever try to solder 8ga wire? I have, I sometimes use a micro torch.

[DANLK66]

This is what I made. I got the plans of the net. It has always worked for me.

Dan

[Andyd103]

to launch my 6 engine cluster i use a lawn mower battery 12v, alot of juice in it, real reliable, made my own launch box and it has never failed to launch them all on a full charge

[Johnly]

Absolutely. The amplitude of the spike depends on coil inductance and switching speed, but can easily measure hundreds of volts.



That should work well.

The good news is that the voltage spike produced by the collapsing field is of the opposite polarity of the energizing voltage. The simple fix is to install a high voltage, high current "catch" diode in parallel with the coil so that if becomes forward biased when the spike is generated.

I suspect that a starter relay would switch 24 volts without a problem, which would help to mitigate the lead losses. That or use Quest Q2G2 igniters in series. 12 Q2G2 igniters would present a total resistance of ~24 ohms, and a 12V system would easily deliver the current needed to have then all fire in about 0.040 seconds.

John

[SCE to AUX]

The good news is that the voltage spike produced by the collapsing field is of the opposite polarity of the energizing voltage. The simple fix is to install a high voltage, high current "catch" diode in parallel with the coil so that if becomes forward biased when the spike is generated.

Yes, that's what we have been talking about. Unfortunately, installing a diode across the relay coil then requires the proper polarity be used when connecting the relay coil to the launch controller (so that the diode is reverse biased while trying to energize the relay). In most cases, the pad clips at launch sites aren't labeled for polarity.

Possible work-arounds for this problem include the use of a small relay (minus protective diode) as a "first stage", which then energizes the larger relay coil (protected with a suitable diode). The downside here is an additional relay to fail.

You can also use a small fullwave bridge rectifier to develop the proper polarity. Connect the pad clips to the 2 AC input terminals, and put the relay coil (and protective diode) in parallel across the + and - output terminals, with the cathode of the protective diode to the + end of the bridge.

With this setup, the bridge will "steer" the output to the proper polarity, regardless of the polarity of the input signal. The only downside here is that the output voltage to the relay coil will be about 1.4V lower than the input voltage, due to forward voltage drops in the rectifier bridge. Most relays have a wide enough "pull-in" voltage spec that this doesn't pose a real issue.

[delta22]

Suggestions about higher voltage are very interesting.

6s lipo battery packs supply about 22V. Two in series would supply 44V.

Series strings of 4 to 8 Rocketflite MF ematches, or series strings of 3 to 5 ML igniters would fire well at this voltage.

Current load would be reduced allowing for thinner lead wire, and possibly a single simple relay.

>>> Any suggestions on a suitable relay that could be triggered by 12V without so large a coil as to cause a troublesome voltage spike on magnetic field collapse?

It would need to handle 50VDC up to 80A. Relay coil trigger circuit would have to be completely separate from higher voltage ignition circuit.

>>> What about a solid state relay?

[SCE to AUX]

Going much beyond 24V actually REDUCES reliability, in my experience.

Once the voltage goes much higher, the igniter bridgewire can sometimes burn through so quickly that the pyrogen doesn't burn, and the motor fails to ignite. The igniters don't so much burn, as explode.

[delta22]

This would be purely for clusters of 7-30+ motors.

Igniters/ematches would always have to include series wiring so as to provide a 4v to 12v drop per igniter.

I wouldn't attempt to fire a single 12v igniter with 44v for exactly the reason you specify.

[SCE to AUX]

>>> What about a solid state relay?

SSRs are nice, but you need to use one which is specifically designed for switching DC loads. They are available, but nowhere near as common/cheap as the ones meant for switching AC. Switching DC with an AC type SSR generally results in an output that turns on OK, but then latches ON until the load current is interrupted.

For "abusive" service like a launcher, you'll want to oversize the relay a bit in terms of current handling. And don't forget the need for a good heatsink!

[rocket9005]

How about this ...

http://www.pratthobbies.com/proddetail.asp?prod=PRM-12

Doug make good stuff, and it is reasonably priced.

[delta22]

How about this ...

http://www.pratthobbies.com/proddetail.asp?prod=PRM-12

Doug make good stuff, and it is reasonably priced.

It looks like a good product, but not enough amps for the extreme clustering I like to do.

[delta22]

I built the cluster box.

Started with a small tool box I had not been using, about 14" long. Cut and sanded a 3/8 piece of plywood. Mounted all the electronics to the bottom and stored the wires on top of the board.

Power is a Turnigy 5.0 Ah Lipo 4S 14.8V battery, picked up from HobbyKing for $65. Battery is rated 40C (200A) continuous, 50C (250A) for 10 second bursts.
As I tracked the order I discovered they ship from Hong Kong.

Power wires are Turnigy 10awg, very fine stranded wire with silicone insulation. Low resistance while being remarkably flexible.

Used a small 40A rated relay to activate the big 200A relay. Big relay purchased from partsgeek.com was 1990 Ford LTD Crown Victoria Starter Solenoid $26.39.

Bottom line:
1) complete cluster box weighs about 6lbs (battery 1.3lbs)
2) club system activates the small relay and is isolated from the rest of the system
3) a LOT of power is available on the heavy duty black power lines when needed

[delta22]

Comparing performance - Actual measured values using 1ohm resistors in parallel.


Launch system similar to a good club system using relay. 12.6V 22Ah AGM battery with about 10ft of 16awg power leads.

ohms...volts....amps...watts
1.00...10.75....10.8.....116
0.50....9.55.....19.1.....182
0.33....8.60.....26.1.....224
0.25....7.90.....31.6.....250


Cluster box. 14.8V rated, 15.38V measured at no load, 5Ah 40C Lipo battery, with about 8ft of 10awg power leads.

ohms...volts.....amps...watts
1.00....14.88....14.9.....221
0.50....14.40....28.8.....415
0.33....14.00....42.4.....594
0.25....13.60....54.4.....740
0.16....12.8......80.0....1024

Crunching these numbers shows that a good typical club type system has an internal resistance of 0.15ohms, while the cluster box has an internal resistance of 0.03ohms.

Comparing systems with a 0.25ohm load, club system has dropped to 7.9V and delivers 250W, cluster box is at 13.6V and delivers 740W.

When the cluster box is putting out over 1000watts its output voltage is about the same as a lead acid battery at no load.

I had to measure voltages quickly because the 10w Radio Shack resistors started smoking almost immediately due to the excessive power they were getting.

(had to put the periods in to space numbers apart in the post)

[delta22]

The high power circuit is protected with a 175A fuse.

I have no doubt the cluster box can go a lot further than the 80 amps noted above, just ran out of resistors at the local Radio Shack.

Depending on how I wire the igniters, might draw as much as 100A to fire the 30 motors in the TOGinator pictured in my avatar. Plan on sending that up for its fifth flight in a month.

[Solomoriah]

This is what I made. I got the plans of the net. It has always worked for me.

Dan
Can you upload a full-res copy so I can read the text?

[delta22]

Found a few more 1ohm resistors at another Radio Shack. Tested cluster box output into 10x 1ohm resistors in parallel as pictured.

Actual:

With 0.1 ohm load, output was 11.4V.

Calculated 114 amps current and 1300 watts output power.

Projected:

With 0.034 ohms internal resistance for the cluster box as wired, a 0.07A load is about as low as it is practical to go. The voltage would drop to about 10V, output current would be about 150A and power would be around 1500W.

Lower resistance loads could draw more current, but the voltage drop would be so severe that total delivered power would never get much higher, and system reliability would suffer.

For example into a 0.34 ohm load, output voltage would drop in half to 7.5V, current 213A and maximum theoretical output power of 1738W is achieved. But the fuse likely blew and the battery's life may have been shortened.

[JRThro]

If I remember from college, you get maximum power transfer into a load when the load resistance is the same as the source resistance.

Even though college was 30 years ago, I seem to have remembered correctly:
http://en.wikipedia.org/wiki/Maximum_power_theorem

[Handeman]

I used motorcycle/garden tractor batteries for a lot of years, but I recently got a car starter from Home Depot. For $50 you get a 350 Amp starter that will fire any cluster I ever heard of. It charges with at standard extension cord, has charge level meters, an emergency light and USB port to charge anything that charges from powered USB ports.
http://www.homedepot.com/h_d1/N-5yc1vZ1xh7/R-202019917/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Works great, is easy to transport, and can start your car if you let your battery run down playing tunes at a launch all day.

[delta22]

If I remember from college, you get maximum power transfer into a load when the load resistance is the same as the source resistance.

Even though college was 30 years ago, I seem to have remembered correctly:
http://en.wikipedia.org/wiki/Maximum_power_theorem

I stumbled on this outcome as I was modeling outputs into different loads in Excel.

When I saw this, as it did for you, it stirred memories from electronics courses in college decades ago.

[delta22]

I used motorcycle/garden tractor batteries for a lot of years, but I recently got a car starter from Home Depot. For $50 you get a 350 Amp starter that will fire any cluster I ever heard of. It charges with at standard extension cord, has charge level meters, an emergency light and USB port to charge anything that charges from powered USB ports.
http://www.homedepot.com/h_d1/N-5yc1vZ1xh7/R-202019917/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Works great, is easy to transport, and can start your car if you let your battery run down playing tunes at a launch all day.

Car starters can be a very convenient power source for rocket launches. That is what I am using to power the launch system described above as "typical" of a good club system.

One factor that is VERY important is the power wiring. In a low-voltage high-current system, voltage drop in the wires is huge.

MOST of the voltage drop in the values I quoted in previous posts is due to power wires. In both systems the wire resistance is more than half of all the launch system's internal resistance.

Please note that in post 4, the 12V battery is capable of over 200A output, but the system with 10ft 16awg leads will not deliver more than about 8V at 30A.

With the 10awg leads, huge relay, and 14.8V Lipo battery, have been able to deliver over 110A at over 11V. I will be firing a 30 motor cluster with this next week, the TOGinator in my avatar and at bpasa.com.

[RimfireJim]

For the kind of current you are running, I don't understand why you don't go bigger than 10AWG with your leads, at least for the majority of their lengths. Flexibility doesn't seem nearly as important as low resistance. Compared to the rest of your system, they strike me as a significant "weak link".

[cjl]

For the kind of current you are running, I don't understand why you don't go bigger than 10AWG with your leads, at least for the majority of their lengths. Flexibility doesn't seem nearly as important as low resistance. Compared to the rest of your system, they strike me as a significant "weak link".

I have to agree here. Although the ratings aren't that relevant for short current pulses, 10AWG wire is only rated for 30A, so I would be strongly tempted to go up to something like 6 or 8 AWG if I were building such a box.

Even with the 10AWG though, it still seems to be able to source a tremendous amount of current, so it shouldn't be too much of a problem.

[delta22]

When talking about short bursts of electrical power in a system where electrical codes do not apply, the key is the resistance of the wire.

16awg, used in many a typical launch system, has 4ohms of resistance per 1000ft.

10awg has 1ohm of resistance per 1000ft.

For 10 ft leads there is a 20 ft round trip for the circuit.

16awg, 10ft lead, 20ft x 0.004ohms=0.08ohms
or about 1V drop per 12.5A current due to leads

10awg, 10ft lead, 20ft x 0.001ohms=0.02ohms
or about 1V drop per 50A current due to leads

I was concerned that heavier leads would be very prone to pulling out the rocket's igniters. Wanted wires that could follow the rocket for 3-4 feet as it lifted off.

The Turnigy (hobby RC) wire I used has very fine strands and silicone insulation, making it far more flexible than any other 10awg wire I have ever seen.

[delta22]

As I am building experience with Lipo batteries in general and this one in particular, I discovered that the battery charger had stopped charging previously due to an arbitrary timer and not because the battery was fully charged.

Ran the charger until the battery was fully charged at 16.8V and ran three more tests:

Cluster box. 14.8V rated, 16.75V measured at no load, 5Ah 40C Lipo battery, with about 8ft of 10awg power leads.

ohms...volts.....amps...watts
1.00....16.0.....16.0.....256
0.50....15.5.....31.0.....481
0.16....13.9.....86.9....1208

I will be flying projects this Saturday that will have igniter resistance loads in this range. One is here: http://www.rocketryforum.com/showthread.php?t=8817

[Rex R]

you might look into aquiring some 'limp noodle' battery wire, I know that castle creations gets some in 8ga (and its a real pita to solder connectors on it too).
rex

[delta22]

The cluster box worked perfectly at the 7/17/10 CMASS Amesbury, MA launch.

Fired 48 motors in 3 clustered flights with no ignition failures, using Rocketflite ML igniters for almost all motors.

First flight was an 18" Applewhite saucer "Saucer of DOOM" on 7x D12-0 motors.

Made series strings of 3 Rocketflite ML igniters and wired 3 of these in parallel. Two extra igniters used for a test to build confidence for the following flights.

Igniter net resistance about 0.8 ohms. Box pushed about 19A at 16V into this or about 300W.

Second flight was an upscale FlisKits Thunderbird on 11x motors
1x ProX F30 White (24mm 3gr - new motor)
3x Estes E9
7x Estes D12
Thread with more info and pictures here: http://www.rocketryforum.com/showthread.php?t=8817

Used 2 series strings of MLs 2 long for the outboards, 2 series strings 3 long for central ring of motors, and ProX supplied ematch for the F30.

Total igniter resistance about 0.36 ohms. Box supplied over 40A at over 15V or more than 600W.

Third flight was the TOGinator on 30x motors
1x ProX I236 Blue (38mm 3gr)
2x ProX H133 Blue (29mm 3gr)
27x Estes D12
1200 Ns full J cluster
Thread with more info and pictures here: http://www.rocketryforum.com/showthread.php?t=13352

Used 3 series strings of MLs 2 long, 8 series strings 3 long, plus redundant ProX ematch for central I motor.

Total igniter resistance 0.16 ohms. Box pushed 85-90A at about 14V or 1200W to launch this.

As can be seen in the second TOGinator picture, sparks from the ignition of the upper motors lit the tops of some of the lower motors, causing the barbecue effect. It could be said that there were 50 ignition events in that flight despite the fact that there were only 30 motors.

Before these three ignitions the no-load battery voltage was 16.78V, after it was 16.75V, so lots of battery capacity left.

[Solomoriah]

holy

crap

:eyepop:

[delta22]

Used the cluster box again at the end of July and twice in August to fire the Turbine Rocket Saucer. This is an original design inspired by FlisKits' Frick-n-Frack and Applewhite's saucers, combining clusters with saucer and helicopter design features. More pictures plus flight details and movies here: http://www.rocketryforum.com/showthread.php?t=13727

The "TRS" was fired 8 times at these 3 launch events. Every launch was powered by clusters of (mostly D) Estes 24mm motors - 7 launches on 4x motors and one on 8x.

Used Rocketflite ML igniters for all flights. For some launches, igniters were wired all in parallel, for others in series strings two long then assembled in parallel (to reduce current load).

First 3 pictures show the 8 motor cluster flight wired in combined series and parallel. Last two pics are a 4x motor flight with motors mounted in a more canted position to maximize spin.

36 motors were installed in these 8 flights and all motors were fired.

Cluster box has now fired 84 motors in 11 flights with no ignition failures.

[delta22]

The cluster box was featured in the Jan/Feb 2012 issue of Sport Rocketry in an article titled "Lightning Cluster Box, Electric Sledgehammer: 1300 watt output from a six-pound box!".

Got questions from folks looking to build their own. What follows is some additional info that may be helpful. Please feel free to post here or private message me with questions.


Wiring Diagram:

The attached image is a higher resolution copy of the wiring image in the article. I never drew up a neatly done wiring diagram, but this image shows all wiring connections.


Big Relay:

Polarity needs to match the relay's instructions going onto the activation coil for the big relay.

The part number I used was SS-598. Partsgeek does not seem to carry it anymore.

It can be found here, but the price has gone up: http://www.autopartswarehouse.com/details/QQFordQQCrown_VictoriaQQStandardQQStarter_Solenoid QQ19921997QQSISS598.html

It is likely that any relay specified for a 1990 Ford Crown Vic would work well, because they are rated for 200A and have a clamping diode, reducing the voltage spike created when the big relay is de-activated.


Fuse:

The black part with copper tabs is a 175A fuse that I picked up at AutoZone: http://www.autozone.com/autozone/parts/Bussmann-Fuse/_/N-9ciet?counter=68&itemIdentifier=32346_0_0_

to protect against a short.

Late last year the fuse failed, broke inside without being exposed to high current, and it is no longer part of the circuit.

For a club launch system that is likely to be handled by a number of people, a fuse would be a good precaution. I picked this one because of the high current rating and I could connect to it directly with screws, so no fuse holder or extra wiring was needed.
.

[Zonie]

If it were me, I'd build a complete launch system and work with the BoD to set it up for your flights. If they have to push the button, then so be it, put the controller on the LCO's table.

Clustering requires patience, time, and attention to detail, as you well know, so hurrying to setup your project on a club pad is not the way to go.

I have been to "other club" launches with torture racks. Hate 'em. :puke: We fly misfire alley in both of our clubs here in Phoenix and it works soooo much better, and everyone builds their own GSE, which is half the fun. we have some cool pads and controllers out here. You misfire, you simply recycle and fly when your card comes to the bottom of the stack again (we load a box top down and pull the oldest out a slot on the bottom) Nobody waits...

[[POW]Eagle159]

I have launches 2 twin engine rockets and a 3-engine rocket, using a 24 volt battery, 35' of stereo wire and a simple button. They have worked perfect so far. The 1 safety system is the wire can connect/unconnect directly from the battery.

Here are the rockets...

[delta22]

2012 Year-End Update:

Just completed a LOT of updates to my rocketry website including many pictures and videos of fun cluster flights: www.bpasa.com (http://www.bpasa.com)

Have been using the cluster box for most of 3 flying seasons with excellent results.

Starting 7/2010 and continuing through 12/2012, the cluster box has been used for all my clustered flights firing 5 to 30 igniters at the pad, and most flights firing 4 igniters:

Year - Cluster Flights - - - - Motors - - Number
- - - - using Cluster Box - - Loaded - - ignition failures
2010 - - - 22 - - - - - - - - - 154 - - - - 1
2011 - - - 16 - - - - - - - - - 140 - - - - 2
2012 - - - 23 - - - - - - - - - 176 - - - - 1
Total - - - 61 - - - - - - - - - 470 - - - - 4

Sorry about all the dashes, couldn't get a clean table to show up here.

Bottom Line:
Using the cluster box and Rocketflite igniters has produced 99.1% successful motor ignitions over 3 years, firing 466 of 470 motors attempted in 61 clustered flights.
The combination of the cluster box's very high power output with high quality Rocketflite igniters has been very effective at successfully igniting clusters.

Notes:
1) For flights firing 6+ igniters I normally wire igniters in series strings of 2 or 3 and then combine these in as many parallel sets as needed.
Please see bpasa.com Rocketflite and TOGinator pages for pictures and more information on combining series and parallel wiring of igniters.
This is done to balance voltage vs. current demands of clustered igniter system.
2) Clustered flights in 2012 used Rocketflite's new CF (ClusterFire) igniters, which use their lower current MF wires with a pyrogen that burns almost as long as their excellent ML igniters.
3) Also used CF igniters to fire all 18 deployment ejection events with no failures in 2012.
4) Clustered flights in 2010 and 2011 used Rocketflite's ML igniters.

30 engine cluster fired by cluster box:


http://www.youtube.com/watch?v=M-3dYlUGUyE&feature=player_detailpage