# Big Bertha on E

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#### RalPh8

##### Well-Known Member
In the beginning of the month I had my childhood big bertha make a splash down on a small lake at our ranch. I waited till it floated ashore and picked it up. I let it dry for a few days and then tried to remove the C motor that was in it. Well, it ripped out the whole inside, centering rings and all and left me with just the airframe. So I made some new centering rings from thin plywood and found a 24mm tube that used to be the airframe for a recently-CATO'd Estes Eggscalibur. I cut the tube to size and fit it in the new centering rings. I then sanded them down to fit the Big Bertha and voila! Big Bertha with a 24mm MMT was born. If you haven't upgraded some previously 18mm rockets to 24 or even 29mm, I recommend doing so! It was cool to see it go so much higher and faster than what I was used to on C motors.

#### teepot

##### Well-Known Member
TRF Supporter
I have a Big Bertha with a 29mm mount. 18 ounces. a G80 will go to 1800'.

#### SCooke123

##### Well-Known Member
Nice- at least you repurposed it and got it flight ready again.

#### RalPh8

##### Well-Known Member
Nice- at least you repurposed it and got it flight ready again.
Yep! As long as I can recovery it I figure it’s fixable. Like even turning a cato’d airframe into a mmt.

#### DAllen

##### Well-Known Member
I have a Big Bertha with a 24mm mount. Way better flier on D's and E's IMHO...Might have to try the 29mm thing though. That sounds like fun.

#### RalPh8

##### Well-Known Member
I have a Big Bertha with a 24mm mount. Way better flier on D's and E's IMHO...Might have to try the 29mm thing though. That sounds like fun.
Agreed

#### Mike Haberer

##### Well-Known Member
TRF Supporter
I kit-bashed a Boosted Bertha to 24mm mounts. A lot of fun to fly....

#### Back_at_it

##### Well-Known Member
Bertha should be a 24mm rocket right from the start. Yeah it'll fly on a B and C but D12's make it interesting.

Here is one of mine on an F44-8

#### mo2872

##### Well-Known Member
Bertha should be a 24mm rocket right from the start. Yeah it'll fly on a B and C but D12's make it interesting.

Here is one of mine on an F44-8

Nice........I'm cloning the Estes Phoenix currently, modding with ply CR's and ply fins for the express purpose of burning some F39's in it.......thinking it might be similar.....

#### Back_at_it

##### Well-Known Member
Nice........I'm cloning the Estes Phoenix currently, modding with ply CR's and ply fins for the express purpose of burning some F39's in it.......thinking it might be similar.....
That Bertha has a full length coupler minus about 3/4" at the top so the nose cone still fits. Funny thing is those are the stock balsa fins.

#### Mike Haberer

##### Well-Known Member
TRF Supporter
Bertha should be a 24mm rocket right from the start. Yeah it'll fly on a B and C but D12's make it interesting.

Here is one of mine on an F44-8

Mine sims out to almost 2000 feet on an Apogee E6-4 (5.8 sec long burn). Need a calm day, a blue sky and a big field....

Super Big Bertha sims to 1160 feet on an Apogee F10-4 (7 sec long burn).

You get the slow realistic launch of a Big Bertha on a B but with more altitude and long burns.

#### RalPh8

##### Well-Known Member
Mine sims out to almost 2000 feet on an Apogee E6-4 (5.8 sec long burn). Need a calm day, a blue sky and a big field....

Super Big Bertha sims to 1160 feet on an Apogee F10-4 (7 sec long burn).

You get the slow realistic launch of a Big Bertha on a B but with more altitude and long burns.
Agreed! And nice video!

#### buddah3360

##### Member
Hey guys! I recently built the super big bertha and have a question! This is the first e rocket ive built and I know on the smaller rockets, there's a metal brace that holds the rocket in place. On the Super Big Bertha, what holds the motor in place? I couldn't find anything in the instructions or online. Any guidance will help! I think maybe there's a engine block that was supposed to be installed?

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#### mo2872

##### Well-Known Member
Hey guys! I recently built the super big bertha and have a question! This is the first e rocket ive built and I know on the smaller rockets, there's a metal brace that holds the rocket in place. On the Super Big Bertha, what holds the motor in place? I couldn't find anything in the instructions or online. Any guidance will help! I think maybe there's a engine block that was supposed to be installed?
Masking tape thrust ring on nozzle end of the motor. Kit should have a plastic screw on retainer to hold it all in.

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#### SharkWhisperer

##### Well-Known Member
Hey guys! I recently built the super big bertha and have a question! This is the first e rocket ive built and I know on the smaller rockets, there's a metal brace that holds the rocket in place. On the Super Big Bertha, what holds the motor in place? I couldn't find anything in the instructions or online. Any guidance will help! I think maybe there's a engine block that was supposed to be installed?
Like all of the Estes Pro series, there is a plastic screw-on retainer ring that holds the motor in (Quick release). Everything else is similar to standard--motor tube with centering rings and an engine block...

Easily modded to whatever motor will fit inside the body tube. That said, I've seen several screw-on retainers lost during flight/recovery, probably because they weren't tightened down sufficiently (but not too much!). They'll last a good while, but I always have extras in my ever-expanding build box.

Bertha is a classic and a peach!!! I gave an unopened "regular" Bertha kit to my GF a few weeks ago for congratulations on something we were celebrating that was also projectile-related but didn't involve balsa, but she's apparently since lost interest....so I might need to swipe it back and start yet another build in the dark of night, bwahh hah ha!!!

Everybody (I think), even the speed demons, appreciate a big fat gorgeously slow take-off that you can see until apogee without binoculars, at least on occasion. Bertha and her super big sister fit that well.

And Buddah3360, I just noticed that was your first post on the site--though a newbie (here) myself, and on behalf of my compatriots...WELCOME!!!

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#### buddah3360

##### Member
Masking tape thrust ring on nozzle end of the motor. Kit should have a plastic screw on retainer to hold it all in.

So I just wrap more tape around the motor to hold it in place? Lol I see that in the instructions, I just thought there would be more that holds it.

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#### BEC

##### Well-Known Member
Bertha should be a 24mm rocket right from the start. Yeah it'll fly on a B and C but D12's make it interesting.
24mm motors didn't exist when it was designed. It first appeared in the April/May 1963 Model Rocket News. The kit was introduced some time in 1965 and first appeared in the Estes catalog with the 1966 edition. It's been in continuous production since—making it the longest running model rocket kit ever.

That said, I find Q-Jet C12s and D16s give a stock Big Bertha a good kick, and I have built one or two with 24mm mounts, including flying one on one of those just-barely-more-than-an-E F44s. Zoom!

#### teepot

##### Well-Known Member
TRF Supporter
My Big Bertha came with a 29mm mount. G80 to 1800' plus.

#### mo2872

##### Well-Known Member
So I just wrap more tape around the motor to hold it in place? Lol I see that in the instructions, I just thought there would be more that holds it.
Put tape around it such that it pushes Against the mount tube when inserted. Then screw the retaining ring on. The tape holds it during thrust, and the ring holds it during the ejection charge.

#### Back_at_it

##### Well-Known Member
So I just wrap more tape around the motor to hold it in place? Lol I see that in the instructions, I just thought there would be more that holds it.

That appears to be a 24mm Estes E motor. The mount on the Super Big Bertha is 29mm. If you want to fly a 24mm in a 29mm mount you needed the adapter.

#### mo2872

##### Well-Known Member
That appears to be a 24mm Estes E motor. The mount on the Super Big Bertha is 29mm. If you want to fly a 24mm in a 29mm mount you needed the adapter.

DOH!!! Good catch......I didn't realize SBB came with a 29mmt......I've not built any of the Bertha's, and I'm a lifer......:hmm:, guess I should remedy that.

#### Back_at_it

##### Well-Known Member
DOH!!! Good catch......I didn't realize SBB came with a 29mmt......I've not built any of the Bertha's, and I'm a lifer......:hmm:, guess I should remedy that.

MO - You're killing me here. How have you not built a Bertha. You need to stop what you are doing right now and correct this injustice. Start with a Super Big Bertha then get a normal Big Bertha but build it with a 24mm mount. Next get a Baby Bertha. Then build a Ranger and finally a Semroc Brighton clone.

Sorry, I'm a bit obsessed with that design.

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#### mo2872

##### Well-Known Member
, I dunno, man, it's just always escaped my wallet? Been shooting rockets since about 1980-ish, everything from the Alpha III to the mighty Saturn. Like I said, guess I'll have to remedy that.......but maybe a 38mm upscale?? LOL...........***mo runs off to browse AC Supply****........

#### SharkWhisperer

##### Well-Known Member
, I dunno, man, it's just always escaped my wallet? Been shooting rockets since about 1980-ish, everything from the Alpha III to the mighty Saturn. Like I said, guess I'll have to remedy that.......but maybe a 38mm upscale?? LOL...........***mo runs off to browse AC Supply****........
I have learned that if I browse a rocketry (or fireworking) sales website, there is a 92% likelihood that I will fill a cart with at least $100 of stuff, most of which I don't really "need" (but I'll find a use for it). And another 90% chance that I'll hit "Complete Order" before my logical brain can step in. #### icyclops ##### Well-Known Member Years ago the Super big bertha’s came only with a 24mm mount with Estes wire motor retainer. The 24mm tube had the motor block further up to accept E engines. It came with a tube spacer to use for 24mm engines and the recommendation was D12-3 or D12-5.....which was about right as it didn’t go very high and needed that faster ejection charge in time for the chute to fully open. I didn’t know the new ones came with bigger motor mounts now....good deal. Showing my age no doubt.... #### SharkWhisperer ##### Well-Known Member I have learned that if I browse a rocketry (or fireworking) sales website, there is a 92% likelihood that I will fill a cart with at least$100 of stuff, most of which I don't really "need" (but I'll find a use for it). And another 90% chance that I'll hit "Complete Order" before my logical brain can step in.
Damn! It happened again. Think I cleared Doug at AC Supply out of half his Estes parts inventory. With a few motors thrown in for good measure. And not one item was I in desperate need of. Except that Red Max kit, of course. Gotta have a Red Max kit in the build pile (more like build mountain).

Where do folks get long coupler tubes that fit Estes body tubes (not the stubby Estes couplers)? Guess I could make 'em from split BTs no prob, or from scratch...

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#### hball55

##### Well-Known Member
I have a Big Bertha with a 29mm mount. 18 ounces. a G80 will go to 1800'.
I have a Super Big Bertha here with the external fillets curing. It only weighs 9.7 ounces and I generally build my rockets heavy. Was your Big Bertha built from the kit or did you build from scratch? 18 ounces sounds crazy heavy for the kit version of the Super Big Bertha.

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#### buddah3360

##### Member
That appears to be a 24mm Estes E motor. The mount on the Super Big Bertha is 29mm. If you want to fly a 24mm in a 29mm mount you needed the adapter.

I don't know the mm of the motors I bought, they are not the size that Bertha wants, but they were the only ones I could find at hobby lobby. I did order the right ones from a place online, maybe those will fit tighter and make more sense. I'm just getting back into rockets, I haven't built them since I was a kid.

#### SharkWhisperer

##### Well-Known Member
I don't know the mm of the motors I bought, they are not the size that Bertha wants, but they were the only ones I could find at hobby lobby. I did order the right ones from a place online, maybe those will fit tighter and make more sense. I'm just getting back into rockets, I haven't built them since I was a kid.
Yeah, Back at it is probably right. Ya got yerself some 24mm E motors when Super BB needs 29 mm Es. The adapter kit is cheap--\$3.59 for a pair (reusable) at AC Supply (Estes Product Code: EST9753; in stock), and probably slightly more at the local hobby shop if they have them. They're simple. Drop your skinny 24-mm motor into the plastic adapter casing and load it into Bertha just like a regular 29-mm fat E. It might not go as high, so be sure to check the delay time on the motors you purchased--if the delay is too long, then you're just asking for either a late deployment when coming in downwards at speed that could damage your rocket/recovery gear, or even a dangerous lawndart. Neither would be enjoyable on your maiden flight!

Have fun. Check your motor specifications. Cheap plastic adapter=problem solved so long as you are using an appropriate motor.

#### CalebJ

##### Well-Known Member
TRF Supporter
MO - You're killing me here. How have you not built a Bertha. You need to stop what you are doing right now and correct this injustice. Start with a Super Big Bertha then get a normal Big Bertha but build it with a 24mm mount. Next get a Baby Bertha. Then build a Ranger and finally a Semroc Brighton clone.

Sorry, I'm a bit obsessed with that design.
I keep going back to the AMW site and looking at this one: