School me on clusters

[Theory]

Truth be told, I have never been much of a cluster kinda guy... no real reason, just wasnt my proverbial "cup-o-tea"

That said, I am looking for a challenge, and I'm beginning to think that a medium to large cluster capable rocket might fit the bill. Possibly a LOC Ultimate, or if they wold kit it up, an Ultimate Max complete with a e-bay and RNWS.

My question comes down to lighting the motors, specifically Aerotech motors. I have a large quantity of Aerotech cases and do not want to begin a project that will require me to purchase a bunch of CTI hardware. Mention CTI as I am aware that their motors are more "cluster friendly"

Say I went with the LOC Ultimate, and wanted to fly a cluster of three G138s, or maybe two H165s, is there anything that I need to be cognizent of to help ensure simultaneous ignition? Likewise, if I went with the Ultimate Max, and added an I300 to those same three G138s...

In the past year I have switched from Aerotech initiators to those sold by WM and have had fantastic success. Would these still be the best to use?

Trying to get a good idea of what I'm in for before actually pulling the trigger.

thanks all!

 

[Nytrunner]

The G138 and I300 are Blue Thunder and should light easily.

The H165 is Redline and could light slightly behind the blue (AT red isnt super hard to light, but not as easy as AT blue)

If it was a 38mm motor or larger, Id recommend a sliver of a pyrodex pellet in the top grain (makes it like a CTI motor), but not sure about augmenting 29s

 

[Mugs914]

Cool thread Sean, I'll be watching for sure... Like you, I've never really given too much thought to clusters until recently.

I've been flying rockets on and off since I was about nine and just flew my first LP cluster model earlier this year!

 

[Theory]

thanks Ny. know that the AT Blue is easier to light, however , want to better understand the how and what the best method is.

does adding a pellet to the top grain turn the motor into an EX? this is an important aspect as one of the two clubs i fly with is a NAR club and they do not allow anything EX.

i like the idea of the a 5 or 7 motor rocket for this as it gives me many configuration options, to include a single motor.

you bet Mugs, lots for me to learn here. i had an Estes Impulse back in the day that was a dual 24mm cluster. a pair of D12s was fun, but nothin like three or four HP blue thunders!

 

[Bat-mite]

Stay away from green AP for clusters!

Might it be worth your while to start with something smaller, like a Fliskits Richter Recker?

 

[teepot]

I'm also interested in what others use. I built a semi scale Atlas 5 with 6 srb's. So I'll need to light 7 motors at once. I was planning on using Twiggy ignitors by Quickburst. Anything else I should consider?

And what is WM?

 

[Blast it Tom!]

Bookmark! Back in the day, I'd self designed, built, and string tested a nice 3-engine cluster for Estes "D" engines. Beautiful rocket. Never got to get painted or flown as my childhood family CATO'd and I don't know what happened to it. I'm considering a rebuild just for "closure" and oh, the technology I can pick from now! AT reusable casings, longer 24mm motor casings, composite propellants... WOW! So thanks for starting this thread and for all who have/will contribute to it.

 

[Theory]

WM is Wild Man Rocketry.

not sure if we can link to sites or not, but if you hop on the Wild Man page you can find them under "lighters"

i had a real run of bad luck with the AT initiators, probably a 50% failure rate. not good for clusters. after switching to these, ive been at 100%

Bat-mite, thank you for the idea, though im not really looking to cluster BP motors, and small composites can be tricky as the very small nozzle throats limit the kinds of starters that can be used. ...and agreed on the green propellants!

 

[RocketflierVB]

Something to think about... Clustering is expensive (using 2-6 additional motors vice one). I made a (7) cluster 29mm from a 4" BSD Horizon kit to fly on (7) G-80's. Very impressive flight but in reality it flew on a $130 "J" motor (cost at the time, 2003) somewhere around $200 now...

Don't get me wrong, I did it for the challenge and it felt good when it worked. You need to think about flexibility in your construction. Are you planning to hit them all at launch? Mixing colors will wash each other out. I built a compartment to hold a timer to light, say (4) on the ground and (3) in the air, or any variety of combos and colors. Using the same formula at launch increases your odds of getting them all to light. A little pyrogen in the ignitors doesn't hurt either.

What I really want to try is using (6) Metal Storms at launch and just before burn-out hit a Warp 9...truly going to warp speed...

Eric

 

[Theory]

looking to do this for the challenge and for something "new to me"

honestly, im not in rocketry to save money... though i will most definitely save where i can.

flexibility is why i will build with a central motor allowing for single motor powered flights.

will absolutely run a conduit for air-starts. if / when this gets built, an RRC3 will be a part of the electronics pacakge and it can (should be able to) fire a set of motors.

 

[Rocketjunkie]

I have an Ultimate Max (7 38 mm mounts, 18 flights), an Ultimate (7 29 mm mounts, 5 flights), a 3" downscale (7 24 mm mounts, 8 flights with altimeter and more with motor ejection), and a BT-60 downscale with 7 13 mm mounts for my Rx 13 mm reloadable motors.
Ultimate on 7 F15 ematches in nozzles.
Ultimate Max on I284 and 3 H70 outboards fuse lit.

Ignition.
Electronics, either timer or all-in-one. Use a separate unit for recovery. You will need to run conduit for wires to the outboards. Most accurate.
Fuses, Skylighter sells fuses that work. Ignite ground start motors with pad, run fuses to the ground start motors to air start them.
All motors ground start, ematches like those used for ejection will start BP motors. Just insert them as far as they will go and tape them in place. CTI motors are your friends for igniting ground start clusters as they have BP pellets in the core and use ematches.

 

[heada]

I have a standard Ultimate which I use 6x F42 and 1x H180. As said, its more expensive than a J motor that it adds up to.

The F42's are Blue and light nearly instantly. The H180 is a white and takes a little longer to get going. The H180 normally starts about 10 feet off the ground. This is known and planned for but something to be aware of. Different motor types start differently. Either know and plan for that ahead of time or stick with all the same motor type. I also remove the ejection charge from 4 of the F42s leaving 2x F42 and 1x H180 for ejection (F42s set for desired delay, H180 for a few seconds longer). Having all 6 go off at nearly the same time would be way over-kill and possibly damage the rocket. Last, the launch controller needs to be able to source enough current to fire all the starters at the same time. A relay based system is required and even then, good fresh batteries too.

 

[Blast it Tom!]

Hmm. My launch box has a 12V lawn tractor battery in it, and an automobile ignition switch/high current rated momentary pushbutton to fire (LPR guy here, still learning...) What are the advantages of relays?

And should we be calling these sorts of rockets "Rapid Motor Disposal Units (RMDU)?" (As seen elsewhere on this forum...)

 

[Rocketjunkie]

BTW, I prefer to use ground start motors that will provide a safe flight and use electronics for deployment.

And should we be calling these sorts of rockets "Rapid Motor Disposal Units (RMDU)?" (As seen elsewhere on this forum...)

That's what the Motoreater series of rockets is for, first flown in 1990. This is the largest with a 98 and 8 54 mm mounts in 1999.


The lugs you see on the side are for a 1" rod. Rods work fine as long as they're big enough.
The original size is still going after 72 flights. (54 and 8 29 mounts in 5.5" airframe.

 

[cerving]

Colored motors (red, green) take longer to light and should be avoided for clusters, or any other application where relatively fast ignition is required (i.e. two-stage sustainers). You should use a good igniter for clusters... I'll second the recommendation of the Quickburst igniters, they'll light just about anything. The ones that Aerotech is shipping now are garbage... if you have some with the skinny yellow and orange wire, toss them aside and get some good ones (Quickburst, Wildman, etc.)

 

[heada]

Hmm. My launch box has a 12V lawn tractor battery in it, and an automobile ignition switch/high current rated momentary pushbutton to fire (LPR guy here, still learning...) What are the advantages of relays?

And should we be calling these sorts of rockets "Rapid Motor Disposal Units (RMDU)?" (As seen elsewhere on this forum...)

Standard launch controllers send the power down the wire from the controller to the pad. At a distance of 200'+, the wire has to be very thick to support the amps needed to fire 7 starters at the same time. Low voltage systems (12v is still low voltage) just can't do it at distance. A relay puts the battery at the pad and the only power you're sending from the controller is the signal to flip the switch at the pad. Relays are standard at most club launches but you need to talk to the club to make sure their relay system can handle large clusters. I went to a launch where the club had weak batteries and the 7 motor cluster just sat there doing nothing because the battery at the relay didn't have the juice to fire all 7 starters in parallel.

 

[Blast it Tom!]

Standard launch controllers send the power down the wire from the controller to the pad. At a distance of 200'+, the wire has to be very thick to support the amps needed to fire 7 starters at the same time. Low voltage systems (12v is still low voltage) just can't do it at distance. A relay puts the battery at the pad and the only power you're sending from the controller is the signal to flip the switch at the pad. Relays are standard at most club launches but you need to talk to the club to make sure their relay system can handle large clusters. I went to a launch where the club had weak batteries and the 7 motor cluster just sat there doing nothing because the battery at the relay didn't have the juice to fire all 7 starters in parallel.

Much thanks, sir, that makes much more sense to me. With LPR you don't need to be nearly as far away, nor have nearly so much amperage:



(I can't resist posting that just about everywhere...!)

 

[Tim51]

My question comes down to lighting the motors, specifically Aerotech motors. I have a large quantity of Aerotech cases and do not want to begin a project that will require me to purchase a bunch of CTI hardware. Mention CTI as I am aware that their motors are more "cluster friendly"

I'm not an expert but I'll chip in with a few observations on what I've learned so far. I've yet to fly Aerotech so cannot comment on their suitability, but what I would say is that even with CTI I've found there's always the possibility of clustered motors not coming up to pressure at precisely the same time. This was something I was mindful of when planning my only hpr airstart build so far (below). So I built it with 4 large fins, the motor mounts clustered close together and enough nose ballast to give it 1.5 calibre stability on the biggest motors it could take. I've been flying it with J or K 54mm cores and H or I 38mm outboards. It doesn't deviate significantly even if one of the outboards kicks in after the other, or doesn't light at all. After 3 flights I'm pretty much hooked.

 

[Theory]

thank you all

this is most helpful! will look into the Quickburst starters

is there a reason to use a dedicate unit for the air starts and not the open chanel of an RRC3? looking to learn

 

[cerving]

It's a good idea to have some kind of off-axis detection on the airstarts, so you don't light them if the rocket isn't relatively "straight up". You can use velocity@time, altitude@time, accelerometer/baro altitude comparison, or some kind of IMU-based solution for that... check your airstart electronics to see what it supports.

 

[Theory]

It's a good idea to have some kind of off-axis detection on the airstarts, so you don't light them if the rocket isn't relatively "straight up". You can use velocity@time, altitude@time, accelerometer/baro altitude comparison, or some kind of IMU-based solution for that... check your airstart electronics to see what it supports.

roger that!

thank you

 

[DeeRoc29]

For larger reloadable motors, redundant e-matches and Pyrodex pellets work for me every time. I've got a LOC Esoteric with a 5x54 mmt. Most recently, I did a K550W in the center, two J401FJ, and two CTIJ355 reds. All lit on the ground with two e-matches dipped in BKnO3/nitrocellulose lacquer AND a Pyrodex pellet in each motor.

For smaller, single use motor clusters, I'd stick to AT Blue Thunder or CTI motors that have the built in pellet. I have a THOY Nighthawk that does really well with dipped e-matches. Shown here are 7 G80T single use motors.

Yes clusters are basically more expense per Ns, but they're AWESOME.

 

[Theory]

thank you all!

looks like i need to be taking a good look at the starters and the propellant that is used. ...good thing i am a huge fan of AT Blue Thunder!

 

[Theory]

based on optical observations alone (what i can see from the old internet and what i have in my range box) the starters/initiators/things that light the motor sold by WildMan look to be the Quickbursts

back to the question of grain augmentation. does adding a pyrodex pellet to the forward most grain make the motor an EX?

also, any concern around "too much igniter" and a CATO?

 

[Ez2cDave]

Back to the question of grain augmentation. does adding a pyrodex pellet to the forward most grain make the motor an EX?

Not unless you tell someone that you did it . . . LOL !

Dave F.

 

[heada]

based on optical observations alone (what i can see from the old internet and what i have in my range box) the starters/initiators/things that light the motor sold by WildMan look to be the Quickbursts

back to the question of grain augmentation. does adding a pyrodex pellet to the forward most grain make the motor an EX?

also, any concern around "too much igniter" and a CATO?

I add pyrodex pellets to some of mine but only in larger motors (38mm+) I view it as no different than painting the top grain with a pyrogen or using slivers of BT propellant. As always, check with your RSO before you do it.

As for "too much igniter", it can happen but I've found that as long as you don't constrict the nozzle opening too much then you'll be fine.

 

[Wayco]

Crazy Jim (blackjack 2564) used to make Wildman's starters, but not sure if that's still the case. I'm familiar with some of the ingredients that he uses, but wouldn't publicly list them. Most of my success at winning drag races is due to his mentoring.
jsdemar has posted up some info. regarding BkNo3 and viton that might help you:
https://www.rocketryforum.com/threads/boron-and-viton-available.150798/#post-1860731

looking to do this for the challenge and for something "new to me"

honestly, im not in rocketry to save money... though i will most definitely save where i can.

flexibility is why i will build with a central motor allowing for single motor powered flights.

will absolutely run a conduit for air-starts. if / when this gets built, an RRC3 will be a part of the electronics pacakge and it can (should be able to) fire a set of motors.

I'm not much into saving money either, so when I fly "Tweety Bird" (my Icon picture) I use a big, powerful motor in the central 54mm MMT and CTI motors airstarted in the four outboard 54's.
Last flight was with a central Loki M1378, two J430's and two J250 skids outboard. The M1378 is plenty of motor to get things rolling, and it's started with the ground system. If you are really concerned with modifying AT motors, just spend the money for CTI.
If I wanted to light AT motors with an RRC-3, I would use ematches wrapped up with ground up blue streak (or equivalent) propellant. I have also used the pyrodex 50 cal. pellets, but prefer to "roll my own" starters.
I beat Wildman in a drag race a couple of years ago when he somehow lost his ignitor on the walk out to the pads and Sharon just happened to have one of his regular lighters available, which are not known for starting quickly. I should just leave it there, but just so you know, pyrodex pellets won't fit through a medusa nozzle. Hey, he picked the motor!

 

[beeblebrox]

Truth be told, I have never been much of a cluster kinda guy... no real reason, just wasnt my proverbial "cup-o-tea"

That said, I am looking for a challenge, and I'm beginning to think that a medium to large cluster capable rocket might fit the bill. Possibly a LOC Ultimate, or if they wold kit it up, an Ultimate Max complete with a e-bay and RNWS.

My question comes down to lighting the motors, specifically Aerotech motors. I have a large quantity of Aerotech cases and do not want to begin a project that will require me to purchase a bunch of CTI hardware. Mention CTI as I am aware that their motors are more "cluster friendly"

Say I went with the LOC Ultimate, and wanted to fly a cluster of three G138s, or maybe two H165s, is there anything that I need to be cognizent of to help ensure simultaneous ignition? Likewise, if I went with the Ultimate Max, and added an I300 to those same three G138s...

In the past year I have switched from Aerotech initiators to those sold by WM and have had fantastic success. Would these still be the best to use?

Trying to get a good idea of what I'm in for before actually pulling the trigger.

thanks all!

If you are going to be at the MDRA launch this weekend, I will be there on Saturday. I can help you out. I am definitely a cluster expert. There are several options I will not discuss here. You can PM me for more information. - Scott

MY latest cluster rocket: 1 x 38mm central, 4 x 24mm outer. This flight I208 redline EX motor + 4 Estes E12-P

 

[RocketRev]

Way back at the first Texas LDRS, (Pat G ran a great launch and got a lot of help from Lauretta) I had a buddy who tried three or four times to get a 38mm research motor to ignite without any success. We were parked next to each other. He even tried two igniters at the same time. Nothing he tried worked. So naturally, I bet him a six pack of his favorite personal liquid propellant against a six pack of mine, that I could get that motor to light on the next attempt. He figured that he was about to have me buy him his 6-pack choice and we shook on it. I told him to open up the forward end of his Kosdon 38/640 motor case. My buddy's normally green colored propellant was black with igniter pyrogen residue. I scrapped off some of this residue in the the top grain and inserted a single pyrogen pellet. He put his forward closure back in and put the snap ring back in place and put it back in the rocket. We walked out thru the RSO station, then out to the pads. When Pat got to "ignition/fire" the rocket leaped into the air for a great flight.

Ah, the IBC Root beer was especially good that evening and into the next day!

These delightful little pellets work very well in clusters too, as others have said.

Brad

 

[teepot]

Would a pellet work in a single use motor?