Successfully Combined Staging and Clustering

Scratchbuilt two-stager with two 18mm motors per stage. Four 18mm motors in 2x2 configuration. I devised the split booster stage to guard against non-simultaneous upper stage ignitions. BT-60, 41”, 4.5 oz. Flew it for the first time on 5/26 with 2 B6-0's in the booster stages and 2 A6-4's in the sustainers. It was quite a show. Close scrutiny of the videos and photos shows the upper stage motors ignited about .5 sec. apart. Looks like the split booster staging was the right idea.

Congrats on a great design and a great flight! The pic with the split booster I the air is really cool.

That split booster is a great idea!
Congrats on the successful launch.

That is really awesome. I don't think I have ever seen any commercially built kit with a split-booster staged cluster before. This may be the first of its kind. Estes MIRV, has split sustainers lit from a single booster and Seattle Rocket Works MIRV Gryphon has split sustainers lit from a clustered booster, but I don't recall ever seeing a split clustered booster. Pretty clever, and your flight proves the point, that the boosters don't have the exact same burn times.

Love the split booster idea. It would be fun to make the boosters glide...

Maybe I'm dumber than everyone else but I don't see how the staging works, or how the split booster figures in. Can you provide any more details? Looks cool.

Congrats. Very cool. For 2 to 2 model, you design is a great idea in case the booster engines burn through at different times.

Another benefit is likely the decent profile of your boosters after separation. Tumble recovery is tough on booster fins. Each of your boosters after separation should have a V shaped profile from the front, with the heavier engine at the point (bottom) of the V. So should fall Fins Up, Engine Down. So I am guessing higher probability the boosters hit the ground engine first.

I like Mugs idea of making the boosters glide. Something along the lines of the Edmonds Twinsee design for the boosters might work.

https://archive.rocketreviews.com/reviews/all/edm_twinsee.shtml

or a Mod of the MPC Lunar Patrol.

https://castlerocketeer.blogspot.com/2018/05/mpc-lunar-patrol-part-14-booster-decals.html

I once had a booster that inadvertently lost the 29 mm BP motor casing while tumbling. Apparently, it was stable without that weight. It was cool to watch it glide....right into the woods at the edge of our launch site.

Thanks for all the comments. The boosters tumbled down without incident onto the grass field. I agree turning them into gliders is an interesting idea. I could try adding some nose weight to each one and balance them to get the CG to the right spot. Might work.

I’ve added some more pictures to demonstrate the idea. Upper stage is 2 motor cluster. Two taped engine stacks are inserted. Each booster has a full 18mm motor tube inside the half body tube. Not totally aerodynamic but it works.

That is pretty cool. Very cool, actually. Been a few years since I've messed with rocket design; first thought is what would adding weight to nose of boosters, and therefore to tail of flight stack, do to balance of the flight stack?

Now I get it. Each half-booster can eject separately when it stages. Very very nifty.

Nice design, I may need to steal it.

GlenP said:

That is really awesome. I don't think I have ever seen any commercially built kit with a split-booster staged cluster before. This may be the first of its kind.

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I thought I had seen commercially available split clusters before. I was thinking it was from US Rockets, but looking at their website, I am not seeing it. As I recalled, it was something like the Triple Trouble or HiTest that had the 3 motor mounts projecting from main airframe for the sustainer. The 3 boosters were just short lengths of motor tube with a single fin attached to each one.

Maybe I just looked at Triple Trouble and mind simmed the cluster lighting issue.

Of course, one could CHAD stage a cluster, but this is way, way cooler. I salute you!

In fact, I'd like to see others replicate, duplicate, and elaborate on this idea. Perhaps someone with the time and inclination can attempt a 3x3 or 4x4 motor configuration. Or just maybe a 2x2x2. Lots of possibilities limited only by the tail weight you'd be adding. The idea started when my 10 year old son asked if we could combine staging and clustering. I had to ponder it for a long time before coming up with this. He also made the styling decisions for this rocket.

That's one of the things kids are best for. The question might be easy to answer or hard (like this one) but you'll never answer it until someone thinks to ask. Your son deserves both thanks and congrats on a really good question. (Which is not to detract from the thanks and congrats due you for a really good answer.)

Right on!

As long as all your cluster motors light and no CATO'S things are good. A 4x5 rack Rocket would be cool. 20 motors of pure awesomeness.

I did a 4x3 tractor motor staged cluster with A10's last year called Sharknader. Had one of the A10-0's CATO but it still flew. The out of sequence ignition worked out with all the upward inertia.

All that weight on the bottom with many inefficient black powder motors would make it more challenging.

Go for it!