Super Big Bertha----What a Pain To Build!!!

[Initiator001]

(snip)

I have no idea why the tube isn't pre-slotted; that is below standards for MPR kits these days. Might have to do with the expense of automating tube handling for the rotary stage in a laser cutter? I know at least one local manufacturer that has an ingenious multi-tube rotisserie fixture for his laser that allows doing some number of tubes at once. There's really no excuse for that one except the manufacturer lacking the capability.

(snip)

At the time the SBB was being released Estes' parent company (Hobbico) wanted to save money by not slotting the tube. It was cheaper just to include a marking/cutting guide for the fin slots.

FYI the SBB was originally going to be packaged in a bag. When the first shipment arrived from overseas the body tubes were damaged from the way the kits were packed in the shipping box. Estes changed the kit to be packaged in a box.

 

[Initiator001]

That's no longer true. The AT G12ST is just around the corner, will take a SBB to 2000 feet, but REALLY weathercocks badly on a slow end-burner if there is any wind, like, more than 2MPH.

The G12ST is a 'plugged' motor so the modeler will need to use some sort of electronic ejection system to deploy the recovery system when this motor is used.

 

[BEC]

The biggest issue for me is the Estes airframe. It's way too thin. With the big fins it weathercocks badly in just about any wind. It zippered on it's first flight, and that's with having added a coupler just below the nose cone for added strength. The zipper stopped at the coupler. I repaired with another coupler and lengthened 3 inches. The second flight it weathercocked and was underpowered on an F23FJ (same engine as first flight). It did a parabolic dive into a creek - and then the ejection charge went off.

I'm on my second rebuild now. I had to design a custom 3D printed coupler since I already had couplers the entire length of the airframe that wasn't damaged. On this rebuild I'm going to add an Eggtimer Apogee altimeter in the nose cone for head end deployment at apogee with motor ejection backup. If it craters this time, I'll only rebuild as a custom build with LOC tubing and plywood fins for G's and H's. Estes shouldn't do rockets with 29mm MMTs at this point. They skimp on the design to make them fly-able on BP motors and, at least in the case of the SBB, it's a lousy design. Love the rocket, hate the design.

I fly mine on the recommended motors. I don't have issues with severe weathercocking though it IS a Big Bertha, which has plenty of stability, so some weathercocking is to be expected. With your experience, I can only suspect that yours has been "improved" with weight-adding reinforcements. The peak thrust of the more recent F23FJs (https://www.nar.org/SandT/pdf/Aerotech/F23FJ.pdf) is just a touch more than the Estes E15 or F16 has, and it comes to full thrust much faster, so liftoff speed shouldn't be an issue unless it's overweight.

Mine is almost dead stock, except it has a two-tube Semroc baffle installed and a pair of rail buttons so it can fly off a rail as well as a 1/4 inch rod. It weighed 9.52 ounces (no motor) when it was first finished. It's gained a quarter ounce after a dozen flights and a change to an 18 inch Top Flight thin-mil 'chute in place of the stock 24 inch plastic one. Most flights carry an altimeter and sometimes also a Chute Release. None have been as you describe.

Clearly as designed it doesn't meet your expectations. It does meet the intent of the design very well, at least for me. I'm just sorry I can't get the 29mm Estes motors at Hobby Lobby any more, or I'd fly it much more often than I do.

The one I'm flying now is my second one. I'd probably still be flying the first one except that I treed it during a winter launch and what I got back after much wind and rain wasn't terribly salvageable.

 

[Underdog]

I'm a beginner and SBB is my first "completed" rocket so I can only compare it to a Madcow Mozzie that I never finished. I did warp one of the fins when laminating them (had to make a 5th) and as others have mentioned, the walls of the body tube are thin, so slide a smaller tube inside when cutting the slots for the fins. As a beginner, I made my share of mistakes but had fun figuring things out. As I was waiting for glue/paint to dry I checked out "Rock Sim" and websites with thrust curves. I added an ejection baffle, rail buttons, and a nylon parachute.

This 36.8-inch rocket is designed to be big and light. I fly on cheap "D" motors from Hobby Lobby with a 24mm adapter. The 2.6" diameter SBB goes up nice and slow puts on a real show. Hard to find anything like this for a "D" motor. I think you will be happy with this rocket when you start flying.
(I'm eager to try the newly retooled and inexpensive black powder "E" motors that supposedly don't explode and then on to Der Red Big Max)

 

[Scott_650]

This 36.8-inch rocket is designed to be big and light. I fly on cheap "D" motors from Hobby Lobby with a 24mm adapter. The 2.7" diameter SBB goes up nice and slow puts on a real show. Hard to find anything like this for a "D" motor. I think you will be happy with this rocket when you start flying.
(I'm eager to try the newly retooled and inexpensive black powder "E" motors that supposedly don't explode and then on to Der Red Big Max)

You’ll like it even better on an E12. I’m not all that much of a BB fan - I don’t really care for the nose cone shape, I like the earlier slightly more pointed Ranger nose cone better - but the SBB is the one rocket I fly at every club launch.

 

[RobertH3]

Semroc has a motor mount and fin replacement kit for the SBB. Doesn't take away from the thin tube and no ttw slots though. I replaced the fins, motor mount and sleeved the model with coupler. In addition I framed in the fins with basswood half rounds...SBB Bruiser! You can also add a layer or three of cardstock to the stock cardboard rings. Use the original rings as templates.

Cheers / Robert

 

[DeWain]

I'll just reiterate what BEC said. This kit was designed to be light enough to fly on Estes E16 and F15 motors. Solid plywood fins and thick-walled body tube would indeed be stronger, but there is no way that it would fly on E16 and F15 motors.

This kit is a classic Large Model Rocket (LMR), which is a fun category of rockets for those of us who enjoy good ole' black powder motors. My BT-60-based Orbital Transport in my thumbnail picture is a good example-- it's just a larger version of the original blackpowder-powered kit. It is fine if someone prefers stronger mid power kits that fly on stronger composite motors-- it's just a different critter than a LMR.

 

[Bill S]

I had some issues with the built-up fins, as I had never done those before. Mainly in that I foolishly used Saran Wrap to cover both sides of the fin while it was under some heavy books to keep it flat. Unfortunately, I failed to anticipate that the Saran Wrap would keep the glue from drying and I took the books off after say 4 hours, only to find later on that they warped when they finally dried. Ugh. Next time I'll let it sit a day, then remove the wrap and put books back on it, leaving it for a couple days...

I did add some complication to the SBB kit (for my wife), in that I added a BT-60 stuffer tube and thin styrene 1/8" tube to run a kevlar cord from the back of the engine mount up to the front to attach the parachute to. See pic:

 

[kevin.mcgee]

I appreciate your point about the PITA build steps. Just as a point of reference I keep three grades of CA on hand: Super-thin, regular, and gap-filling.

And I left out that they say to use CA glue to glue the outer fins to the center fin part. I was a little skeptical that the runny CA glue would do a proper job there, so I went to the trouble to use epoxy to finish the fin construction. Someone else here suggested doing the same, so I made extra work for myself there, but I bet it was the right thing to do not using CA.

 

[Blast it Tom!]

I had some issues with the built-up fins, as I had never done those before. Mainly in that I foolishly used Saran Wrap to cover both sides of the fin while it was under some heavy books to keep it flat. Unfortunately, I failed to anticipate that the Saran Wrap would keep the glue from drying and I took the books off after say 4 hours, only to find later on that they warped when they finally dried. Ugh. Next time I'll let it sit a day, then remove the wrap and put books back on it, leaving it for a couple days...

I did add some complication to the SBB kit (for my wife), in that I added a BT-60 stuffer tube and thin styrene 1/8" tube to run a kevlar cord from the back of the engine mount up to the front to attach the parachute to. See pic:

View attachment 451847

I tend to use waxed paper for those situations, and I don't fully wrap the fin - just top and bottom so I don't glue to my workbench or books!

 

[kuririn]

I had some issues with the built-up fins, as I had never done those before. Mainly in that I foolishly used Saran Wrap to cover both sides of the fin while it was under some heavy books to keep it flat. Unfortunately, I failed to anticipate that the Saran Wrap would keep the glue from drying and I took the books off after say 4 hours, only to find later on that they warped when they finally dried. Ugh. Next time I'll let it sit a day, then remove the wrap and put books back on it, leaving it for a couple days...

Try a sheet of wax paper on both sides of the fin assemblies, weighted down with a heavy book, and left overnight.

 

[Blast it Tom!]

Try wax paper on both sides of the fin assembly, weighted down with a heavy book, and left overnight.

GREAT MINDS THINK ALIKE!

 

[kuririn]

Outdrawn by Tom.
No wonder they call you Blast it.

 

[Blast it Tom!]

Outdrawn by Tom.
No wonder they call you Blast it.

Well, actually I took that name here as a cross-up between my longsuffering wife's frustrated outbursts at me and something to do with rocketry that would actually be positive from our point of view. She never really says "Blast it, Tom!" It's more like "What do you think you're doing? Honest to PETE!"

(Some kids never grow up! )

 

[Underdog]

I used CA per instructions (not knowing any better). With "Rapidfuse slow setting CA" from Walmart, you get 3 minutes to put things in place and it cures in 30 minutes. One fin did warp.

 

[boomtube-mk2]

Am I the only one that has noticed that on many of the Estes' kits the "fin wrap" doesn't properly wrap around the body tube?

This leaves you with the fins improperly spaced around the tube.

 

[Blast it Tom!]

Tolerances can be a bear. A BT-80 is listed as 2.600 diameter and I measured it as such with my caliper- you need a light touch! So I hustled upstairs, made a fin guide with AutoCAD, printed it out measured it - looked good! Until I wrapped it around the tube and it came up 1/16th short. Any error in diameter measurement gets multiplied by pi on circumference; any compensation for paper thickness, paint thickness, etc... My second shot nailed it. This is for a V2 and you DON'T want to be off on those masking lines!

 

[kuririn]

Am I the only one that has noticed that on many of the Estes' kits the "fin wrap" doesn't properly wrap around the body tube?

I've seen worse from other manufacturers.
The mantra in carpentry is "Measure twice, cut once"
For model rocketry I would suggest that it should be "Check and dry fit twice, glue once."

For the OP, the practice of dividing large fins/wings into components that need to be glued together is nothing new. The Estes Space Plane comes to mind from 50+ years ago. IIRC the wing was made up of five pieces.
Using standard width balsa sheets keeps the kits affordable. Other manufacturers do the same, like the Apogee Flying Machine and X-15.
For TTW fins and cutting slots, there are some MPR manufacturers who supply you with an unslotted tube rather than pre-slotted. No big deal once you get the hang of it. Using an angle tool and multiple light strokes cutting deeper each time helps to prevent punch through. A long coupler also helps if you have one.
If these building techniques seem overwhelming and frustrating to you, may I suggest the 3D printed kits from a manufacturer like Boyce Aerospace? Easy construction, great looking final product.
To each his own.
Laters.

 

[Bill S]

Thanks guys for the suggestion to use waxed paper. Should have thought of that before using Saran Wrap, but shite happens.

 

[dr wogz]

The Mega Mosquito" also has the three layer fin design.

And to some:
just sounds like you're being lazy.. Or you don't care too much for "Building" and would rather [perfect parts] to "assemble" overnight..

Cutting parts, building 'structure' and then bringing all these 'parts & sub assemblies' together is what the hobby is to a number of us.. (Don't bother with a 'Launch Pad' kit or some HPR kits..)

 

[Back_at_it]

Maybe I'm just cranky today, but I'm half way through building the Super Big Bertha (Estes Series II) and I'm really exasperated with some of its build features:

1) What's the deal with making the parts count so high on the fins? When you take the outer fin, then glue on that little extra piece, then do the same for the other side outer fin piece, then glue both of them to the center fin part to make one fin, you've got five pieces for one fin. Times four fins, you got a parts count of twenty, when you could have had just four---for four fins made to the proper thickness. Instead you had to assemble twenty parts. Crazy.

I'd accept that the fin build-up was required for the extra strength it presumably gives you for flying on F engines, but if that's the case, then why is the engine mount so flmsly----those cheap cardboard centering rings instead of wood?

2) Then there's the totally gratuitous step of having to cut in the slots into the body tube for the fins to go through. Really? Did I really need to cut out the fin slot template, tape it to the body tube so I could then cut the slots out?

And, once you've got that far, the directions give no admonition to test fit the fins into the engine mount before you glue the thing in---just to make sure the fins will fit in the engine mount slots, avoiding a botch job if they don't fit. I wonder ho many novices got that far only to be disappointed that you didn't line it all up correctly?

I swear, if Estes wanted to actively dissuade a young or a novice builder from ever bothering with another rocket build, they couldn't have designed a kit with so many gratuitous, extra steps.

Or is it just me, being cranky and all??


I've got the fins nearly on now, so I'm home free for the rest of the build---I hope.

Not really sure where to start. I've built several SBB, MDRM and Mega Mosquitos all with the layered fins.. I've never had an issue with the parts count or the assembly process. Here is my take.

- The SBB is a higher skill level so it is expected that you have a certain competency and skill level before building.

- The Layered fins are done for strength but also to keep weight down. Thick Balsa is expensive and would not provide the strength that the Plywood centers with the balsa outer offers. Make it strong but keep it light. It's worth noting that replacement fins in Plywood are available from a couple of different sources if you want to go down that road.

- I'll agree that the paper centering rings are a bit of a cost cut on a rocket designed to fly on motors up into the F range. I personally replace the upper rings on anything larger than BT55 with plywood as I use it as an anchor for my Kevlar. I've seen paper upper rings fail on rockets like the Maxi Alpha and Executioner after repeated flights so I tend to beef these up a bit. While I wish Estes would begin using Plywood, I just don't see it in their future.

- As for the fitment of the centering rings of the motor mount. If you follow the directions and place the rings in the correct location at 1/2" , 3" and 7-1/2" you won't have any issues. If you do, a little sanding on the fins will make everything fit.

- Cutting fin slots is part of the game. Since you have been building since the Johnson Administration, i'm sure you remember when we had to cut the fins out using templates. Cut, glue and sand teardrop of the constellation and we won't even talk about the fins and tower on the old Redstone. How does this compare to those days.

If the SBB is too much of a build process, Estes and other brands have other skill level rockets that will fit your needs. We picked up a few rockets for the girlfriends nieces, ages 6 and 10. One of them was the SBB. I'll be supervising the build in next month or so but they will be building it on their own. I'm only there to keep them from hurting themselves. I'm interested in seeing the process and curious if they run into any issues during the build and how they feel about build process. Of course they have have already built a Baby and Normal Bertha and they were excited when they found out there was a bigger one.

There are other brands out there that don't even give you instructions. Just a bag or box full of parts and a note that says good luck.

 

[Back_at_it]

And I left out that they say to use CA glue to glue the outer fins to the center fin part. I was a little skeptical that the runny CA glue would do a proper job there, so I went to the trouble to use epoxy to finish the fin construction. Someone else here suggested doing the same, so I made extra work for myself there, but I bet it was the right thing to do not using CA.

Agreed. CA for the fins is a stupid idea. Wood glue is the way to go. Just be sure to place them on a flat surface with something heavy one top while they dry.

 

[Fattbank64]

There are other brands out there that don't even give you instructions. Just a bag or box full of parts and a note that says good luck.

LOL

 

[Scott_650]

For all the contributors to this thread like Bernard, Dr W, Back at it, kuririn, et al who have stated that the SBB meets the design and performance goals Estes intends it to, we all need to pick our favorite aphorism - don’t try and teach a pig to whistle, it wastes your time and annoys the pig comes to mind - and let it go (the discussion point that is, please don’t sing that insipid song!).

The folks who want the SBB to be a MPR/HPR tank of a rocket want what they want. Even though there are dozens of kits in the same general size and cost range that are THAT rocket, they want THIS one to be that rocket, regardless of the intent of the designer. More power to them and their rockets - hot rodding stuff is a great tradition so stuff your low-buck rockets full of plywood, epoxy and nose weight and let them rip! I’ve redshifted more than one kit so I get the appeal (but I like the SBB as designed so there’s that).

Add in the usual small percentage of folks who, as my dad says, would complain if you hung ‘em with a new rope - who’d be dissatisfied with any PSII kit Estes puts out that isn’t a Leviathan or MDRM and really don’t want the current PSII rockets to be anything else. We’re not going to change their points of view so again, fill in your favorite pithy saying. The one that pops up in my head now involves the futility of punishing an already expired equine

 

[BEC]

The one that pops up in my head now involves the futility of punishing an already expired equine

Yup, probably right.....

I consider the Estes R&D Department (@JumpJet) to be a friend and it bugs me when people complain about what are, to me, very well done designs. I also spent many years as an engineer working on derivative products and know what kind of constraints can be put on a design, often producibility or cost-driven, that lead to compromises one would not make if given a free hand. But I suppose I can't expect those who "want what they want" to necessarily care about that. And at this point I'd better just stop.

 

[Cape Byron]

I recall talking to a bean-counter who worked in the car industry when I was in the UK. He bemoaned the fact that one of the newer (at that time) Japanese products wouldn't be imported because of the high cost of the passenger side vanity mirror. It's common in some industries to calculate component parts down to eight decimal places.

 

[rklapp]

Wait until you try their new Level 5 kit. It doesn't even come with instructions. (sorry, couldn't resist)

 

[jimzcatz]

Maybe I'm just cranky today, but I'm half way through building the Super Big Bertha (Estes Series II) and I'm really exasperated with some of its build features:

1) What's the deal with making the parts count so high on the fins? When you take the outer fin, then glue on that little extra piece, then do the same for the other side outer fin piece, then glue both of them to the center fin part to make one fin, you've got five pieces for one fin. Times four fins, you got a parts count of twenty, when you could have had just four---for four fins made to the proper thickness. Instead you had to assemble twenty parts. Crazy.

I'd accept that the fin build-up was required for the extra strength it presumably gives you for flying on F engines, but if that's the case, then why is the engine mount so flmsly----those cheap cardboard centering rings instead of wood?

2) Then there's the totally gratuitous step of having to cut in the slots into the body tube for the fins to go through. Really? Did I really need to cut out the fin slot template, tape it to the body tube so I could then cut the slots out?

And, once you've got that far, the directions give no admonition to test fit the fins into the engine mount before you glue the thing in---just to make sure the fins will fit in the engine mount slots, avoiding a botch job if they don't fit. I wonder ho many novices got that far only to be disappointed that you didn't line it all up correctly?

I swear, if Estes wanted to actively dissuade a young or a novice builder from ever bothering with another rocket build, they couldn't have designed a kit with so many gratuitous, extra steps.

Or is it just me, being cranky and all??


I've got the fins nearly on now, so I'm home free for the rest of the build---I hope.

Yes, you are being cranky. By the time one graduates to something like a SBB, They have more than novice skills. I don't have this kit, but my method would make a fin can with the find/rings /mmt and slide that complete assembly into the body tube, extending the slots all the way to the rear. I build everything this way. Cutting slots is easy.

 

[jimzcatz]

I'm no scientist so bare with me. Wouldn't adding length or adding the coupler towards the nose cause the rocket to weathercock more.??

No

 

[jimzcatz]

That's no longer true. The AT G12ST is just around the corner, will take a SBB to 2000 feet, but REALLY weathercocks badly on a slow end-burner if there is any wind, like, more than 2MPH.

Yea, but the G12 IS FAR from hard hitting. It can barely lift itself