Cool Idea for a HPR cluster

I've been messing around with this idea for a giant cluster for a while now. The basic idea is an giant patriotic FX show. What the idea is, is to take a large rocket, put a 7 motor cluster in it, something like a central 98mm and 6 38mm motors around it. In the tubes would be a Redline M motor, then just before burnout of this motor, air start some J350's or something like that, then have two I357's airstart. This is for the red-white-blue effect. It probably would be best to do it at night or dusk, or something like that. You could probably do several different scales of this. You could do one in extreme high power like this one, then a low high power one, consisting of a I redline motor, then two H128's, then two H220's or something like that. There would be some danger from assymetrical thrust and stuff, timing everything perfect. I would probably have seperate timers/altimeters for each airstart. Play with this idea and see what can be done.

Who would be close enough to see the color of the motors other than the initial redline?

White lightning can be seen a long ways off. I'd do blue first, then a set of redlines, then the white lightning.

-- David

Yeah, that makes more sense to me. It would be cool to have a thick white smoke trail start way up there. BT and Redline don't create much smoke, do they?

Blue Thunder has very little smoke. Redlines don't have too much more either.

Better approach. Do it as EX and use Red, Blue and White grains. They do this all the time at Oburg. Last EX launch were some beautiful Red And Blue motor burns. Very cool stuff.

You have to be careful to use known propellant. The DPS stuff all works with the same nozzle configuration so it's easy, just take 3 reds and 3 blues and put them together in a 6G J motor.

Oh, how I like EX...

Alan

doesnt LOC CUSTOM ENGINEERING make a 98mm and 8 38mm centering ring that fits in a BT-7.51.


https://www.locprecision.com/custom_engineering.htm

Oooh (drooling), large cluster rocket...

This is an idea I have also toyed with for quite awhile. Unfortunately, the funds for a project like this have not presented themselves and I doubt they will anytime soon unless I am lucky at guessing numbers.

You could go with a central 98mm and six 38mm or you could go smaller, down to a 6" airframe, and do one 54mm and six 38mm. If you go with the latter, a perfect flight for it in red-white-blue style would be: One K1100T lit on the ground, then 4 J540R's lit 2.5 seconds in, then 2 J570's lit 5 seconds in. A sweet flight!

I have rocksim files for several extremely large cluster projects if you're interested.

Just my dreams though...

Dave

You could get some cool effects, although cycling through the different colors would put the rocket so high that the colors won't matter much.

Now the pragmatist in me says ...

The FAA will have a cow if you do this outside of a legal waiver for that size configuration. All rules apply for 1 hour after sunrise and 1 hour before sunset for other than modroc flights.

I certainly wouldn't want to be on the same side of the planet with the suggested size of rocket in the air in the dark. Once the motors burn out, you have no idea where the parts might land if something goes wrong.

If you want to do fireworks, buy fireworks.

--Lance.

Yeah, night may not be the best place for a 100lbs. beast with multiple airstarts...

But, I have seen a config. like the one I said on video during the day and you could see all three colors. The key is getting the timing right and putting all this in a very heavy rocket. That way its low and slow.

It can be done though and you don't have to go big. You could have an I300, two I366's and two H123's in a rocket and keep it under a mile, easy!

Dave

Thinking about Maverick's last post, how about a Minee Mag, Warloc(?), or something similar? Something big and bad, 3.9 or 5.5 inches in diameter, with a central H165, then two G64's or 38's, finishing off with F52's or something? they would all use the most reliable igniter with the lowest current needs, like e-matches dipped in pyrogen. Play with this idea.

Normally, you would light your Blue Thunders first since 1.) they light the easiest and that will add to the probability that your cluster will get off the ground safely 2.) they have the highest initial thrust spike which will get the rocket moving at a safe speed off the rod/rail, and 3.) they will be the hardest to see the color for so you put those first. Light the Redlines 2nd for mostly the same reasons as above. Redlines light easier than White Lightning so you'll be at a greater altitude if the White Lightnings don't light. Plus, the White Lightnings are visible from the greatest distance.

Mark,
That was my precise reasoning for my last couple posts.
Couldn't have said it better myself!

Dave

PS- Add a pair of GG to that set after the redlines and you got yourself a real show!

Here's a thought - Call the Gates Brothers.

This whole thread adds new meaning to the term "Burning Money"

No offence intended...clusters are fun.

But I would rather fly a BUNCH of high power rockets (If I flew high power), than one big rocket with a bunch of high power motors.

But that's just me.

I guess it's the challange of getting all those motors to light at the right time.

sandman

Alan,

I disagree, don't do it EX. You've left out one *very* important item. Most propellant cannot be mixed with other types, DPS is an exception, given these caveats. When mixing propellant types (DPS only) you always put the fastest burning grains on the bottom. The simple answer here is if you don't know what you're doing and understand why you're doing it, don't try it, period. There's more to it than just tossing some grains into the same casing and pushing the button. Trust me, even when you know what you're doing, you'll still trash some hardware.

I've done the Chameleon effect with DPS propellant in small motors with great success. I've also done the Chameleon up to and including "M" motors with my own formulae with moderate success. The Blue burned too fast, and the red slightly too slow. Nonetheless two of these were burned successfully at the last EX launch (November 2002) in Orangeburg, SC. I wasn't happy enough with the outcome to try these exact formulas together again. Next time, I'll slow down the blue and speed up the red.

I've also done what the original subject here is all about, clustering colors. The attempt was a J-350 core, two DPS reds and two DPS blues. The rocket had about a 9 to 1 thrust to weight ratio on the core motor and about a 40 to 1 with the core and first two outboards burning together. With this particular cluster loaded in the airframe the result was J-350 lit, cleared the rod, the reds lit and made the J-350 appear reddish. After the flight the Thermalite was pulled from the nozzles of the blues and it had never lit. Not a bad failure, just a failure.

I'd strongly suggest to anyone contemplating trying mixing colors to limit it to a cluster, and not even *think* about trying to mix propellant types in a single casing. Way too much to risk and very, very hard to do it right. I am still learning and I've been doing EX since 97.

David Holloway

>>>>>

Originally posted by aadamson
Better approach. Do it as EX and use Red, Blue and White grains. They do this all the time at Oburg. Last EX launch were some beautiful Red And Blue motor burns. Very cool stuff.

You have to be careful to use known propellant. The DPS stuff all works with the same nozzle configuration so it's easy, just take 3 reds and 3 blues and put them together in a 6G J motor.

Oh, how I like EX...

Alan

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Wait, wait. So I can't just toss 3 blue thunder grains and three white lightning grains into a 38/720 casing! Darn! Well, that explains that mishap

Seriously though, I have never tried anything exp. What is it like? I have heard that a j350 = reload only costs about $12 to make...is that true?

David

Anybody who is seriously "into" rockets is NOT going to save any money doing EX! You've got a significant investment in chemicals, mixers, casings, nozzles, scales, casting tubes, liners, and other various pieces of equipment. Sure, if you look at the per motor cost without the initial investment, they do cost less but, you will probably produce more motors than you normally would have purchased from a commercial source. Therefore, the per motor savings are a wash.

As Mark says, motor savings are hard to find in EX. Factor in the added hazard of dealing with APCP in a semi liquid form (read this as lots of available surface area) and you'll see that it has added risk too. Then there is the time to run the figures, , time to mix and pack or pour, time to cut and core, hardware lost testing propellant etc. Then you need a place to mix and if you don't fly it immediately, you'll need to store it.

Then, most "commercial" hardware isn't up to the task of some of the formulas you could concoct so you'll need to make or buy proper hardware. Since the "commercial manufacturers" need to have a "pourable" propellant to reduce manufacturing labor, their propellant doesn't have the delivered ISP that you can get making your own. By adding extra AP, the mix soon becomes like "cookie dough" in consistancy. This is not pourable and also you then have to pack the grains. The result is a propellant that whips butt on the pourable stuff. Big time! Most commercial hardware (DPS is an exception) won't handle it! So unless you want to just make wimpy stuff, you'll need to invest in better hardware too.

You really won't see any money saved until you purchase your AP/ resin and other chemicals in large lots, and make big motors. The "M" motors I refered to in my earlier post cost me roughly $40.00 per load. Not too bad for 5700 Ns of propellant.

I've long since found the break point where the mixer and all the tools paid for themselves, but I have a "private" field I can launch on that is capable by the NFPA standards of up to "L" flights. Needless to say I fly lots of EX.

If you are considering EX, I'd suggest taking a good long, well informed look at the cost, equipment and procedures required to do it legally, safely and successfully. Then I'd suggest investing first in one of the available documents such as "Experimental Composite Propellant" by Terry McCreary, then read and learn. Terry's website is: https://www.experimentalrocketry.com After reading and understanding the book, take the DPS course, get some "hands on", pool you resources with others in your club who share your interest, have "propellant parties" and do it as a social event. It even makes the whole job easier ion hot weather since you're not trying to pack before the curative does it's job.

Finally, to address one other comment from another post, I've had people ask if they could mix slugs from Aerotech/ Kosdon loads and fly them as EX. I'd guess It happens too, some folks don't get it. And as I said before, if you don't know what you're doing, don't do it. To sum it up in a nutshell, it ain't easy.


David Holloway

Disclaimer: I have no financial interest in Terry's book, or DPS. I mentioned them mearly as examples. I do however, believe in and highly recommend both.

Originally posted by MarkABrown
Anybody who is seriously "into" rockets is NOT going to save any money doing EX! You've got a significant investment in chemicals, mixers, casings, nozzles, scales, casting tubes, liners, and other various pieces of equipment. Sure, if you look at the per motor cost without the initial investment, they do cost less but, you will probably produce more motors than you normally would have purchased from a commercial source. Therefore, the per motor savings are a wash.

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