A Question of Clusters

It may seem pretty obvious to those who have been around the hobby for a long time, but the subject has just presented itself to me.

I have avoided any LPR rocket that called for a cluster of motors, as my thought was it burns through a lot of motors very quickly. Why burn three when one will do the job?
But that's not to say that I haven't tried a two-stage rocket on occasion. The theory being that you could go higher, faster, and still have a return on your investment. (recover both stages intact)

However this last week, someone has gifted me with an Estes "Scrambler" cluster-launched rocket kit. The package is opened, but all parts appear to be there.
It seems to have a clear payload section intended to house an egg. But besides a balsa adaptor that changes size from the payload down to the body tube, the other unique feature is a design for THREE low power motors...B or C motors.

Now, I am certain that by following the instructions (and maybe without) I can assemble this rocket.

But the question occurs, how do you set up the ignition so that all three of the motors fire at once?
Is there some means of ganging the ingnitors (starters) so all the wires combine, like a common fuse?
Or is there another wiring harness that would adapt the alligator clips that my club owns to deliver the battery current to all three motors equally?
Is there a rule of thumb that says all three motors must be from the same package, the same serial number?


It's not that hard a question... it's just one that I've never had to confront before... as it has never been presented to me.

I'm sure there's a simple answer. Any suggestions?

Subscribed.

I haven't done clusters yet but will soon (one is in construction, with 2 or 5 motors).

I plan to use my club's 12V launch system, so I'm pretty sure their is adequate voltage and current. Once your power source is settled, the next issue is finding the right igniter. My setup is going to be applicable to BP motors. I will likely use low-current igniters (not Estes) that will likely have a booster pyrogen. The igniters will have about the same ohm rating and be wired in series (not parallel). I do plan on running a couple of tests to see if they work as advertised.

Greg

There are two basic methods I've used for clusters. The first is a "clip whip", a set of leads with clips that branch off of a common point. The other waythat works well with a three-engine cluster, is to twist one lead from each igniter together. You then make a ring using a paper clip or short piece of heavy solid wire to form a large ring, about the diameter of the main body tube. The second leads of the individual igniters is twisted around this.

I personally use extensions on the igniters and then twist all of one color together and then all of the other together.

You will get opinions about using clip whips and they are fine if they work for you, but I have stopped using them in favor of the extensions.

that way I don't have to worry about leaving the clip whips at the pad.

I use the clip whip method also, but with a different approach than what SBoomer mentions. One lead from each starter is twisted together, and one of the firing leads connected. The other 3 leads are connected to the clip whip (which has 3 wires of it's own ) and the whip is connected to the other firing lead. If you can get Quest Q2G2 starters, I highly recommend them. I had a very successful ignition with this approach, The red lines in the pic below represent the clip whip.

[Why burn three when one will do the job?
But that's not to say that I haven't tried a two-stage rocket on occasion. The theory being that you could got higher, faster, and still have a return on your investment.]
Return on investment. This hobby is all about lighting money on fire

Gary Byrum said:

If you can get Quest Q2G2 starters, I highly recommend them. I had a very successful ignition with this approach......

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Much, much, much better success rates at ignition of all motors when using the new Quest igniters. I would not even bother trying to use Estes igniters.

Kirk G said:

Why burn three when one will do the job?

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Because they are FUN !!!!!

You are going to want to bookmark this site, probably print out a copy.

Check TR-6 on Estes clustering techniques

https://www2.estesrockets.com/pdf/2845_Classic_Collection_TR-TN.pdf

This site has some Centuri notes on cluster design (see pg 24)

https://www.spacemodeling.org/jimz/manuals/cmrdm.pdf

First of all, most excellent gift ! The Scrambler is a classic. So my two cents isn't much different from what others have said: it's about igniter prep and amps. My preference, like BobH48, is to wrap the leads (using extensions when necessary) and use just two clips rather than clip whips. Never heard of any rule about using motors from the same package. But I did learn from my rocket buddies to poke the nozzle of each motor with a small wood dowel to clear path for the igniter tip to contact balck powder. You may want to review some basics:

install igniters: https://www2.estesrockets.com/pdf/Estes_Igniters_and_their_use.pdf

TR-6: https://www.webmonteur.nl/modelraketten/educatie/download/TR-6 Cluster Techniques.pdf

NARHAMS tips (thanks Micromeister): https://www.narhams.org/library/tech/006-Clustering.pdf

<edit>
The Quest Q2G2 igniters require lower current than Estes but they are extremely hard to find now. Which brings up another point, I have no experience clustering the new Estes starters (clear "pyrogen"). I can say that based on a relatively short sample of single motor launches that correct installation is critical; the tip must be in contact with black powder to successfully ignite the motor.

Secure ignition wires to the stand...

I use Sooner Boomer's method with the additional step of soldering the connections. I use solars that I cherry pick from. The ones with the most pygroen wins.

Forgot to mention that my 1970's vintage Scrambler is still flyable.

NAR29996 said:

Forgot to mention that my 1970's vintage Scrambler is still flyable.

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Mine was launched on a windy day in May 1973 in Pennsylvania. I don't think it has landed yet.

samb said:

The Quest Q2G2 igniters require lower current than Estes but they are extremely hard to find now.

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I've heard this for months & months now, and I came up with a reasonable solution. Since I have an ample supply of assorted Estes motors, I therefore have an ample supply of their starters. Last time I ran out of C6-5s, I ordered two packs of Quest C6-5s just so I could have some Q2's on hand. The Quest motors fire just fine with Estes starters and I really don't see any difference in performance of said motors. I only have one cluster rocket which is why I like keeping the Q2's around.

Gary Byrum said:

Last time I ran out of C6-5s, I ordered two packs of Quest C6-5s just so I could have some Q2's on hand.

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I ordered a bulk pack of 25 for the same reason but I didn't mention the Q2G2 igniters because of the problem with finding them.

The Quest motors have a lower initial thrust but burn longer. Not an issue with most of my rockets but anything marginally heavy I just use an Estes motor.

My answer to "why three motors when one will do?" I have not tried clustering yet, but I think the reason we all do this is so have a sense of accomplishment. Learn a new skill, and put it to the test. Congratulate yourself when you succeed. As you've pointed out, there are challenges with clustering that you don't experience by just using a bigger motor--challenges building, challenges wiring, and challenges igniting. There's always the chance that one of the motors won't light, and you get a weird flight angle. So when you overcome the risk, your sense of achievement is even higher.

It's the same with moving up to high power. More challenges, more satisfaction. You've got to admit that launches a 100# rocket to 15,000' is a little more exciting and risky than launching a 3 oz rocket to 500'. Same with clustering. I hope to try it one day, but it's not my focus right now.

DizWolf said:

Secure ignition wires to the stand...

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Thank you, David. Your picture makes it very clear why.
(Love the stunned look on the faces and the guy caught eating an apple! LOL!)

Gary Byrum said:

I use the clip whip method also, but with a different approach than what SBoomer mentions. One lead from each starter is twisted together, and one of the firing leads connected. The other 3 leads are connected to the clip whip (which has 3 wires of it's own ) and the whip is connected to the other firing lead. If you can get Quest Q2G2 starters, I highly recommend them. I had a very successful ignition with this approach, The red lines in the pic below represent the clip whip.

View attachment 184734

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Thanks, Gary. For a second, I was afraid that I just became the subject of an Angry Ignitor cartoon! LOL!


"But what is this Quest, of which you speak?" (I've only ever seen Estes motor packs in the few hobby stores that I've visited.)

Kirk G said:

...
"But what is this Quest, of which you speak?" (I've only ever seen Estes motor packs in the few hobby stores that I've visited.)

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https://www.questaerospace.com/cgi-bin/commerce.exe?display=about


NARAM 56 Manufacturers Forum - Quest's Bill Stine at about 35:00

[video=youtube;ccxMD-SqkKE]https://www.youtube.com/watch?v=ccxMD-SqkKE&list=PLzdBQL1k_NRixOVpY-clC77NNY-adoybJ&index=17[/video]

Kirk G said:

Thank you, David. Your picture makes it very clear why.
(Love the stunned look on the faces and the guy caught eating an apple! LOL!)

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It's typical in HPR clusters to go with long leads. If a motor doesn't light, the rocket easily pulls free. This was a 4x cluster of BP, and only two lit. shockingly two hung on, and it whipped around for the entire burn. (https://www.flickr.com/photos/31757945@N05/sets/72157647766314605)

Definitely NOT an ideal situation. Luckily they held for the entire ride. I believe they used the plugs to hold the ignitors. I'd use masking tape, which pulls free easier.

Why cluster? It's fun and looks cool!

I've done a fair share of 2, 3 and 4 motor BP clusters over the years. The Estes Solar Igniters have always served me well, both in series and parallel. The key is to use a good 12v system and handle your igniters with care. Everybody raves about Quest Q2G2 igniters are "better" for clusters.... perhaps.. I do find them easier with the longer wire leads to twist ends together. I don't really have a "failure rate" with clustering Estes Solar igniters. I have not yet tried clustering with the new "starters".


Jerome

Kirk G said:

Thanks, Gary. For a second, I was afraid that I just became the subject of an Angry Ignitor cartoon! LOL!


"But what is this Quest, of which you speak?" (I've only ever seen Estes motor packs in the few hobby stores that I've visited.)

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Nah, not sicking the Irritable Ignit-er-Starter dood on ya.....LOL. Quest has been around for a zillion years, and if I have to buy motors online, I usually go to the BRS website, where Brian also carries the Quest motors. Probably cheaper than you can get at most sites. If you click the hyper link, it'll take you to the page on Quest motors. He usually carries the Q2G2 long starters, but he's out of those also.

g zilla said:

[Why burn three when one will do the job?
But that's not to say that I haven't tried a two-stage rocket on occasion. The theory being that you could got higher, faster, and still have a return on your investment.]
Return on investment. This hobby is all about lighting money on fire

Click to expand...

https://www.theonion.com/video/in-the-know-should-the-government-stop-dumping-mon,14289/

Why cluster? :y:

For some of us, clustering is all we do. For many people it's a natural step in progressing to higher skill levels in the hobby. When I look at any rocket my first thought is how many engines can I add to this thing? Sometimes it's about building historically. For example a Saturn V had 5 engines on the first stage, therefore, a model Saturn V should too. A Titan III should have 3, etc. Just my opinion.

You have a great rocket to learn from. If it crashes there are 10,000 more just like it to replace it, so no real loss there. Practice on the Scrambler then step up to something more challenging. You may find it addictive. I did.

Verna
www.vernarockets.com
https://www.amazon.com/dp/B00HHJHOK6/?tag=skimlinks_replacement-20
https://www.facebook.com/RocketBabeDustStorm

"Nuff Said!!!

I've only flown a Dual 24mm Cluster three times, but I'm definitely a big fan of Clusters now.

Clusters are just fun!

Clusters are a gateway drug to ruin. Once the dealer gets you hooked, it wears off as your tolerance builds and you need a better high. Then you go for airstarts. and then you add stages, then you are walking on traffic medians carrying a sign the says "Will work for motors". By now the kiddies are asking for shoes and wondering where daddy is. Your ex-wife says something like "Probably out wandering around in the desert looking for his thousand dollar rocket." Sadly, you;ve become an HPR junkie and all your Estes friends have dropped you. You can't fly in the park, you have an unsightly fiberglass rash and your boss has fired you for downloading Rocsim on your work station. All because of one little extra engine. But all is not lost. We're your friends here. We accept you as you are. We are here to help. Hi- I'm Dave and I can't quit buying cases.......

fyrwrxz said:

= Hi- I'm Dave and I can't quit buying cases.......

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Hi my name is David and...... and screw you I don;t have a problem!!!! I just need 2 more 24/40 cases....the loads come in three packs....it makes sense!!! and I don't like cleaning at a launch...what if I need to fire off a cluster i haven't built yet and someone needs to borrow a case to get a cert? It's in the yard sale for $20 less than retail!!! I have to get it now... and IT'S A MILLENNIUM CASE!!!!!!




ummm.... Clusters are cool.