Which do you prefer for a Big Bertha mod? 3-C engine cluster or 24mm E-engine?

[CrocketRocket]

Which do you prefer for a Big Bertha mod? 3-C engine cluster or 24mm E-engine?

I've never done a cluster rocket before nor flown E-engines, so both of these are tempting.

 

[MALBAR 70]

If you build a Big Bertha with a three motor cluster, it becomes a Ranger.
If you decide to build it using a 24mm X 95mm MMT to fly Estes E12 motors, you have many options. You can fly E12's and with a spacer you can fly D12's and C11's as well. You can also construct an adapter and fly it on 18mm motors too.

 

[dpower]

Clusters are always more fun!

 

[Nytrunner]

If you can make an interchangable mount (slots in centering rings catch tabs on the tube) you can have a 1x18, 3x18, and 1x24 (and even 1x29!)

 

[samb]

I did interchangeable mounts on a Fat Boy. I was a fun and moderately challenging fabrication project. An alternative is to make 3 Berthas: 1 18mm, 1 24mm, and 1 3x18mm. 2 things about clusters you need to be aware of: starters and amps.
The Estes clear coated, pyrogen-less starters are very picky about placement in the nozzle. Misfires are a problem with them. Misfires on 2 of 3 motors in a cluster can make for a bad day. The most common alternative is to enhance the tip with some more energetic substances. There are many threads here on that subject.
The standard Estes controller with 4 AA's doesn't consistently deliver the amps needed for multiple motor ignition. A 12 volt system and/or a relay system is usually preferred.

threads about estes starters

threads about cluster ignition

 

[Bruiser]

"If you can make an interchangable mount (slots in centering rings catch tabs on the tube) you can have a 1x18, 3x18, and 1x24 (and even 1x29!)"

I did this on a Citation Patriot. It has the same body tube diameter as the Big Bertha. I actually planned to do it on a Big Bertha but Hobby Lobby did not have them in stock when I went to purchase it so I bought the CP instead. I also built a booster for it as well to fly it as a two-stage. My build thread is here: https://www.rocketryforum.com/threads/estes-citation-patriot.154092/#post-1910203

It gets better altitude with the 24mm D12-5 but the three 18mm cluster is a little impressive but a pita both to build and launch. Pita to build because without centering rings in the fin area the tube is unsupported and the fins will wobble if you don't eternally reinforce it and a pita to launch because you'll need a harness for that and a good ignition source. It's most impressive when boosted D12-0 to D12-5. The staging happens at a nice height where it's easy to see and the rocket seems to go into turbo boost as it continues upward. It's the cat's meow

-Bob

 

[Back_at_it]

An alternative is to make 3 Berthas: 1 18mm, 1 24mm, and 1 3x18mm.

Exactly. Like this. To add in a little more complexity you can do a 3 motor cluster using 13mm motors on the Baby Bertha and call it a Baby Ranger. I can't confirm nor deny that this is on the build table.

Personally, I would build the a single 24mm mount so you can use anything from a B6-2 up to the E12 motors.

 

[MarkB.]

Semroc does make a 3 x18 centering ring set. I used it in a Scrambler and to repair an original Ranger.

It is SEM-RA-3x20-60.

 

[Ez2cDave]

If you build a Big Bertha with a three motor cluster, it becomes a Ranger.

Not exactly . . . It also require a Payload Section !

There are a few other "variations", particularly the Fins.

Dave F.

 

[Mugs914]

That's funny Dave, I was just about to post something about that!

I didn't realize that the Ranger and BB were different until a little over a year ago. I was going to do a Ranger clone and did a bit of research. I thought I might get away with putting a cluster motor mount in a BB kit, but it turned out to not be that simple if you want a true Ranger clone!

I noticed that the nose cones are different too; the BB nose is a bit more dome-shaped, the Ranger is a ever so slightly more "pointy".

Erockets has both nose cones in balsa, by the way.

 

[Mugs914]

BTW - To actually respond to the OP's question, I vote for clustered 18mm all the way!

 

[Nytrunner]

I thought I might get away with putting a cluster motor mount in a BB kit, but it turned out to not be that simple if you want a true Ranger clone!

Geez, those differences just look like production noise from here

 

[Kartman]

Clusters are always more fun!

Says the WOOSH Cluster Meister

 

[Mugs914]

Geez, those differences just look like production noise from here

Yeah, could be for sure. But it did trigger my OCD and I couldn't let it go!

Of course, after all that, I put the Ranger clone on hold and scratch built a retro-original I called Starlifter...


Cluster power!


Like Meat Loaf (in)famously said; Two Out of Three Aint Bad!

 

[nosecone]

13mm mini motor cluster is fun

 

[DWonders]

13mm mini motor cluster is fun
View attachment 441932View attachment 441933

Very nice! Is this with a standard Big Bertha? I just grabbed a Baby Bertha tonight and plan to put a 13mm cluster in it.

 

[nosecone]

Yes, regular Big Bertha kit, with Engine mount from Uncle Mike's Rocket Shop & original BB style balsa nose cone from eRockets.