clip whips

[Micromeister]

Mike:
I had a bad experience with a SPST relay, without going into all the details I crossed a couple leads and lite a motor while hooking up the rest. not a good thing. Those little 10amp contact radio shack relays are ok for 2 or 3 motors but Get a Square-D 40amp/contact Power series relay for the long haul. I've had one power relay that has been working almost monthly for over 20 years. I've replaced at least a dozen of the smaller R/S relays in smaller units in the last two years.
Don't get cheap on your equipment if your going to be launching clusters.

Just to remind folks... The system in the diagram above has successfully launched several hundred 3 to 8 motor BP clusters and a few 3 to 7 motor (not by me) AP clusters using thermilite. Alway Twist the the leads as close to the nozzles as possible, connect the clips at that junction alterateing + & - leads. an 8 clip-whip will ignite up to 8 motors.

Heres a pic of inside the Box on one of my multi-Relay launchers. The H/D relay ignites the motors, the other two 12amp/contact radio shack type relays ignite perlaunch special effects, light duty for a relay..but they still burn up.

 

[Neil]

Originally posted by Rocketjunkie
It's not quite that easy, just having loose BP under the motors will ignite some, probably not all.
Here's how I ignite a 12 motor cluster. All have lit 5 of 6 times.
https://www.tripolisc.org/modules/xgallery/view_album.php?set_albumName=album27
Look at the first few pictures. A flight picture is later in the album.

OK, looks pretty easy, but how do I get the thermalite fuses? where do I buy them? how mmuch do they cost? Thanks.

 

[Micromeister]

Neil:
You have to be over 18 with a LEUP to obtain thermilite, I'm not really sure it's still available. Loose Bp will also require over 18 status, Not sure about the LEUP?
Unless you are flying with a waiver or at least a Notem you likely wouldn't be flying more than 9-C6's or 4 D12'a to stay under the 4.0 oz of propellant and still have to content with keeping the lift off weight of your model under one pound. A 3.3lb 4.4oz propellent LMR notem will give you 5 D12's or some other 3 to 10 motor combinations. Flash pan is really a waste of time and your model. Stick with a Relay system.
If your flying HP "the only place flash pans make any sense at all"... your posting in the wrong forum section

 

[Mike]

Thanks for the info John,
I will go with a 40A relay but Maplins doesn't seem to have any 2 pole 40A ones, I'm thinking of getting two single pole relays, one goes on the positive side the other on the negative. The bad thing with that is I have to energize two coils which means I might need to increase the power in my handcontroller.

Does this sound alright?

 

[Micromeister]

Mike:
You may find DPDT power relays are more of a Electrical supply house item. I get mine for a place called Branch electric supply locally. I'm sure you guys have similar suppliers.

Just for S&G's I found a pic of the business end of my 5 D12 brighthawk. Should help a little seeing the real deal The nichrome in this pic is 30gage but I've used standard Estes igniters in this model. I chose this configuration not because of the number of motors but the layout, to illistrate the use of even clip numbers with Odd numbers of motors.
Hope this helps a little.

 

[vjp]

John,

I noticed in your cluster wiring diagrams that you seem to be
partial to connecting igniters in series, rather than in parallel.
Is there anything that makes this more reliable than parallel
hookups? I've only recently begun clustering (with my 4-motor
Fat Boy), but so far I'm 4 for 4 perfect launches using parallel
igniters rigged with wire-wrap. But, if there's a better way I'm
interested in hearing the reasoning. I'm thinking about a 5-motor
Saturn V for a winter project, and the price of failure where
that's concerned is a little higher than for a $8.88 Fat Boy.

 

[vjp]

Doh! Ignore my last question re. series vs. parallel; I realize now that the +/- marks represent clip attachment points; I had misinterpreted seeing the igniters daisy-chained together as meaning there was one clip at each end. So, they are all in parallel after all.

 

[jflis]

whew! had me nervous there for a minute... LOL

I had John's image up on my viewer, blown up, trying to add some clarity so that I could *see* the series wiring because I couldn't *beleive* that he would actually DO that... LOL

whew!

 

[Micromeister]

Made ya look LOL

I've found over the years getting the power as close as possible to the igniters is a real key to success, second only to knowing you have good igniters in the motors. My cluster launchers all use #8 stranded Copper wire between battery and relay, and minimum of #16 Stranded copper between relay and clips, max length of 24", I really perfer 18" or shorter where possible. Alternating the pos and neg clips at the ingiter "twisted" junctions also reduces the resistance by shortening the nichrome wire of each igniter. These connecting also makes "checking" continuity to each motor a little easier on the pad. The goal is to vaporize the igniters the instant the button is pushed. Over the years this system has provided nearly 100 percent reliability. As I mentioned earlier, after 20year I can still count the unlite or misfired motors in all my cluster flights on one hand, those proved to be Bad Estes igniters straight out of the pack. If you Gonna use Estes igniters..Well any igniter actually PLEASE Check the continuity before and AFTER they are installed in your motors. Heres a very inexpensive continuity checker for use with most igniters..NOT electric matches

 

[Micromeister]

Doh! hit the send button before attaching the dwg @#$###
let's try again..Slower this time
If you exchange a piezo buzzer for the lamp i'm told this checker can be used on SOME electric matches also...I still wonldn't.