Question on cluster shots

[rabidsheeep]

i learned from a rocketry teacher at my camp awhile ago a way to shoot clusters off by putting black poweder underneath the engines in tinfoil... just wonder if this is going to work well...

is there any other way of shooting off clusters? i know multiple wires is another way...

 

[arthur dent]

Hi rabid and welcome to the forum,im sure there's loads of people here who can can give loads of advice on lighting cluster's.The technique you are talking about is called flashpan and its a good way of lighting a large cluster.I use the wire clip whip for lighting my clusters of 3 or 4 motors,it works fine with a 12v battery.

 

[rabidsheeep]

does it matter the lenth of the wire too or just the type?

 

[jflis]

Generally you will find clusters in 2, 3 or 4 motors. 5 motors and up are mostly scratchbuilt and/or specialty items (though they do exist).

For 4 or fewer motors, clipwhips or twisting the ignitors together is the easiest way.

If you choose to twist the wires together then the question of wire type/size is moot as you clip your microclips right on the twisted igniters.

If you go with a clip whip, keep the wire size (gauge) at *least* the same as the wires going to the pad. The thinest wires is the weakest link. Don't make your clip whips the weak link

I've attached a copy of our hints and tips sheet on clustering. in the next reply I show a figure on another method.

hope this helps!

jim

 

[jflis]

The attached figure is from our newest kit, the Tres. This is a 3-engine cluster.

On this model (assuming you don't have a clipwhip), I recommend that you extend the length of the ignitor wires so that you can twist them together and use your standard launch controller and one pair of micro clips to hook it up.

The figure should be self explainatory, but please ask if you have any questions about it.

jim

 

[arthur dent]

I would have thought it be best to keep the wire clip whip as short as is practicle and i made mine using the wire from an estes launch controller.I would think that a low resistance wire would be best.

 

[jflis]

Originally posted by arthur dent
I would have thought it be best to keep the wire clip whip as short as is practicle and i made mine using the wire from an estes launch controller.I would think that a low resistance wire would be best.

well, yes and no...

Depending on your setup. Some controllers have 10-15 feet of wire to the controller, some (specially club setups) may have 30-50 feet of wire. Whether your clips are 6" long or 18" long isn't really going to matter a whole heck of a lot. Stay away from 10 foot clip whips though...

As for "low resistance", yes, but this is easily accomplished by using wire that matches the gauge of the wire to the pads And copper will provide easily low enough resistance and is easily available.

jim

 

[benjarvis]

'Quickmatch' is what you ideally want for BP clusters...

It's a fast-burn black powder based fuse, sheathed in paper, that is used for connecting up firework displays. Not sure how easily it's available in the US but it's about all we use here in the UK for BP clusters..

I've done 160 motors in one go with it, only had two fail to light.


Ben