How to make sure 2 or 3 G in Cluster will all ignite

[Area66]

the question say all, how you make sure you it will not fly on only 1 or 2 ?

 

[DizWolf]

I try to make sure it'll still fly ok if a motor fails. I try to make sure each motor can lift the rocket in case of a failure.

To ensure they light however, I've had good luck using aerotech blue thunder motors. They light fairly easy. I had a failure in one of a dual 29mm cluster last weekend. Both Green motors, but only one lit. Took off, arced over and popped the chute about 500 feet. In the future I'm going to move to better igniters. Maybe that'll do the trick.

 

[Handeman]

I only have one APCP cluster that uses two motors. I make my own igniters because it's 29mm and I fly it on a pair of 29/40-120 and don't want to use the included copperheads. The only time I had a motor fail to light is when I tried to use a homemade igniter and First Fire. I think the key is to match the igniters. Whatever type you use, use two the same so they light and burn with similar speeds and intensities. If one motor lights and comes up to pressure before the other, that is when you can have issues.

 

[Sailorbill]

Depends on what brand motor you are using, Aerotech/Estes Pro or CTI. CTI reloads are pretty reliable when used with the supplied igniters. Aerotech/Estes Pro single use or Aerotech reloads depend on the age, propellant type and igniter used. The new non Copperheads seem to work well with fresh motors.

 

[Area66]

Depends on what brand motor you are using, .

Unless the AT reseller in Canada change courier, I will for sure purchase only CTI

 

[DizWolf]

Unless the AT reseller in Canada change courier, I will for sure purchase only CTI

I've got a pair of 29mm one grain CTI cases. I haven't bought any for them yet, but I plan to grab a bunch to use in my 29mm cluster. Possibly even some 3 grain as well. The supplied ignitors with the CTI are very reliable.

Also, I wouldn't let the courier stop you from ordering AT stuff. He's a sub contractor for delivery services. He gets what he deserves.

 

[Area66]

Also, I wouldn't let the courier stop you from ordering AT stuff. He's a sub contractor for delivery services. He gets what he deserves.

May be I should order everyday something to get him drop the job. He leave the package at post office and he have to pay for it.

Edit I just order a motor, I will order another one wenesday. I pay $ 10 for the shipping the contractor don't make a lot of money if he have to mail it. lol

 

[gdjsky01]

Probably not a real answer, but if you are using CTI it almost has to work. With the pellet at the top, if you get the match to the top, it'll light. For clusters, igniter prep is key. Either short all of them, or don't strip them, but prepare them in advance or at a table with a chair if your RSO is giving you a hard time and wont let you checkin with the matches installed.

You need to be comfortable and methodical. An RSO should understand installing igniters in cluster bent over at the pad is wrong and MORE likely to cause a misfire. Be safe yes. But be prudent. Preparation is key. All my successes were prepped on a comfortable table with shade and a chair.

 

[DizWolf]

Some motors are a pita to thread an igniter in at the pad. CTI G54 with the offset hole comes rushing to mind. So much easier to pull the nozzle, install and then screw together.

 

[CarVac]

Some motors are a pita to thread an igniter in at the pad. CTI G54 with the offset hole comes rushing to mind. So much easier to pull the nozzle, install and then screw together.

I have flown one and helped a new rocketeer insert an igniter into another; no problems either way. Did I get lucky?

 

[DizWolf]

I have flown one and helped a new rocketeer insert an igniter into another; no problems either way. Did I get lucky?

It's not impossible, but on mine maybe I got unlucky. With the rocket on the pad it took me a minute to find where the hole was, and then a bit of poking to get it in. Seemed like a sharp turn from the nozzle to the hole. Fun motor though, good long burn Slots and offsets just always give me the fits.

 

[marcusSRG]

Well, I see everyone's all for CTI, which is a great motor system that's a cinch to cluster, but I will mention that you can cluster AeroTech G motors just as easily and for less money...especially if you have 2 or 3 29/40-120 cases. It just takes a little bit of igniter skill and know how.

First, ensure that you or your club has a 12V launch system (ideally capable of delivering 30 amps, which most should) and CHOOSE RELIABLE IGNITERS! When clustering only two or three motors it's really easy because readily available igniters can be used...particularly AT FirstFire Jrs and Quickburst Twiggys. Ideally you want an igniter with low current draw, a good large pyrogen head and two leads... It goes without saying that Copperheads are NOT recommended for this, although it can be done (yes!). They have a high current draw, small pyrogen heads and the leads suck, even when you separate them. This goes for the Estes Pro Series igniters too. They have tiny pyrogen heads...I had one fail to light a blue thunder motor! But the best choice, IMHO, is Magnelite igniters by RocketFlite. They offer several easy to mix pyrogen kits and have igniter leads of all types and sizes. Go to www.rocketflite.com and pick up some ClusterFire pyrogen (CF-kit) and some FS-12-LA leads and you can cluster up to 12 motors on a standard club 12V launch system. One pyrogen kit makes tons of igniters.

Next, you want to install your igniters properly. Before installing them it is a good idea to test the resistance and continuity of each igniter with a multimeter. They are usually going to be just fine but you need to make sure you don't have an odd ball with high resistance or no continuity. Give each igniter a slight bend just below the pyrogen head and insert them all the way into the motor. Now here's my special tip: ATTATCH your igniters to your rocket. Yes, I said attach them. I've seen failed clusters when one motor comes up to pressure and starts moving the rocket, in turn ripping the still burning igniters out of the other motors, preventing them from igniting. The results are not pretty... I know from experience! I attach the leads to my motor retention. I use either a wood screw or a piece of all-thread with a washer and wingnut to retain my motors. I keep these loose and after inserting the igniters in the motors I take my leads and wrap them around the screw/all thread and then I tighten my wing nut, securing both my motors and the igniters.

Lastly, just wire your motors in parallel by simply twisting all of the left leads together and all of the right leads together. Now make sure your igniter clips are CLEAN and attatch them to each lead bundle but DO NOT WRAP THE IGNITER LEADS AROUND THE CLIPS! Remember, the igniters are attached and the clips need to fly free! Now just do a quick continuity check, countdown and fly your cluster successfully! I would also recommend you PRESS AND HOLD the launch button until the rocket launches… As long as those clips are still attached to the igniters they are pumping juice into them. It's not uncommon to have a slow starting motor....press and hold!

 

[Area66]

Thanks Marcus

 

[new2hpr]

If the LCO and RSO will let you, prep it on the ground out by the pad. Lay it down facing away from the flight line in case of landshark. I was allowed to do so this weekend with a decent size cluster (7 G80Ts) which would have been a pain with the rocket upright on the rail.

As others have said, you need CTI motors with the ignition pellet, or Aerotech Blue Thunder. Both light easily. Also, a good battery with lots of current available.

BTW, all 7 lit and 'twas a good flight.
-Ken

 

[marcusSRG]

If the LCO and RSO will let you, prep it on the ground out by the pad. Lay it down facing away from the flight line in case of landshark. I was allowed to do so this weekend with a decent size cluster (7 G80Ts) which would have been a pain with the rocket upright on the rail.

As others have said, you need CTI motors with the ignition pellet, or Aerotech Blue Thunder. Both light easily. Also, a good battery with lots of current available.

BTW, all 7 lit and 'twas a good flight.
-Ken

Another good point! And do you have a pic of that flight btw?!? What was the vehicle and what igniter setup did you use? Must've had some nice flamage from the G80Ts if they were the new kind!

 

[new2hpr]

Unfortunately, the only pix are of prep and just going off the pad. The flames look like NOTHING at that point, but once they all came up to pressure, it was a nice bright blue with a good roar for G's. Oh, and they were all about 15 years old, too.
-Ken

 

[Area66]

Unfortunately, the only pix are of prep and just going off the pad. The flames look like NOTHING at that point, but once they all came up to pressure, it was a nice bright blue with a good roar for G's. Oh, and they were all about 15 years old, too.
-Ken
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very informative the third pic where we see the ignition wire connected to another rod.

 

[marcusSRG]

Unfortunately, the only pix are of prep and just going off the pad. The flames look like NOTHING at that point, but once they all came up to pressure, it was a nice bright blue with a good roar for G's. Oh, and they were all about 15 years old, too.
-Ken
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Ah, the LOC Ultimate! I suspected that. Mine is upstairs on my workbench awaiting a refurbishing and a timer bay Nice liftoff shot! The old G80Ts didn't always produce a blue flame, and the flame would usually show up later in the burn from what I remember...so yours looks about right!

very informative the third pic where we see the ignition wire connected to another rod.

Yes it is. Ken, is the purpose of the rod to allow the ignition leads to travel with the rocket up the rod in case of slow starting motors? If so that's nifty. I just wrap my leads around my motor retention and let them fly with the rocket...but in doing that you must trust that the ignition clips get pulled loose and not with the bird! That hasn't happened to me yet but your method would aleviate this risk. I might borrow that idea...but what's that wire running from your electronics bay to the igniter rod?? A breakwire? And what igniters did you use?

 

[CarVac]

Are the new higher impulse G80's the New Blue Thunder formulation?

 

[powderburner]

A lot of good advice posted, a big thankyou to you guys who shared your experiences
(Probably some hard-learned lessons in there, I would imagine)

I get the impression that (in order to ignite a composite cluster) a moment of prayer wouldn't hurt

 

[marcusSRG]

Are the new higher impulse G80's the New Blue Thunder formulation?

I think so. IIRC I heard this somewhere, plus you can tell visually. The new G80s have a visible flame throughout the entire burn that's very characteristic of new BT--it's long and thin. The F32T (which, IIRC, is also new BT) also looks this way. That would make you think the new G80T would burn more like a G138T but the 138 has a further modified new BT formula ***i think***....

The old style blue thunder generally doesnt have any blue flame in the SU MPR c-slot motors except right at ignition and sometimes towards the end of the burn on old G80Ts. Core burning old blue thunder (HPR RMS stuff) has its own distinct flame--very bulbous and violet blue--visibly different from new BT. I look at motors too much!

 

[new2hpr]

very informative the third pic where we see the ignition wire connected to another rod.

Yup. That slack keeps your igniters connected as the rocket goes up the rail. Just HOLD THAT BUTTON!
-Ken

 

[new2hpr]

but what's that wire running from your electronics bay to the igniter rod?? A breakwire? And what igniters did you use?

I didn't get a switch wired in yet, so that's the altimeter power connections - twist-n-tape.

Igniters are Firstfire Jr.
-Ken

 

[Dave A]

A liitle extra wire length (use all the igniter come with) and connect them so it can travel up rail with a little cushion there in case one is a little slow starting. ALWAYS WORKED FOR ME.
also, yes faster burning motors tend to light easier, I found that out when staging.

 

[marcusSRG]

Cool stuff

 

[DizWolf]

Are the new higher impulse G80's the New Blue Thunder formulation?

These are Estes G80T's, which I would assume are the new formula. I've got a pair of AT G80T's (137N) I'm going to try next time to compare.

 

[BEC]

Before installing them it is a good idea to test the resistance and continuity of each igniter with a multimeter. They are usually going to be just fine but you need to make sure you don't have an odd ball with high resistance or no continuity.

This is sound advice even if you fly CTI. I've had two CTI igniters that were open (no continuity) right out of the package. On a single motor that's just grumbling while I change it out. On a cluster flight..... the ramifications are a little greater.

 

[marcusSRG]

These are Estes G80T's, which I would assume are the new formula. I've got a pair of AT G80T's (137N) I'm going to try next time to compare.

NICE shot!! Scratch build? The Estes and AT G80Ts are identical I'm pretty sure.

 

[DizWolf]

NICE shot!! Scratch build? The Estes and AT G80Ts are identical I'm pretty sure.

Yea just some LOC tubing, a payload section and a sunward 2 x 29. Was a lot more flame than I expected.

 

[new2hpr]

These are Estes G80T's, which I would assume are the new formula. I've got a pair of AT G80T's (137N) I'm going to try next time to compare.

Very nice! And yet very different from my ancient G80's. Might have to try some of the new ones.

So, for maximum photogenic appeal, what 29mm motors would give the best on/near pad flames?

I never get good shots of my rockets in the air, so "up-the-rail" is my only chance. No, I don't think my rocket will handle 7 H268R's, so keep the recommendations reasonable, but it should be able to handle mid to full J total impulse.

Yes, it'd be easier (and cheaper) to just put a single 54mm mount in, but this is a different kind of fun. You either get clusters or you don't.
-Ken