ESTES PSII Super Big Bertha - Build Thread

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Pull_and_Twist

Weekend Rocketeer
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Hey everyone... decided I would throw together a build log while I assemble my ESTES Pro Series II Super Big Bertha. Pretty excited for this kit!!! I plan to keep most things stock but will be turning the coupler into a baffle and adding wood to the centering rings.

DAY 1:


Inventoried all my parts.

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Decided I would start with the nose cone... it wasn't too bad, but the seams were visible.

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I hit it with some 220 grit sandpaper and got it nice and smooth. Glad I didn't have to use any filler on it.

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With that done I decided to start working on the fins. I contemplated cutting my own out of plywood but decided to try the five piece balsa set that came with the kit.

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After sanding the fin skins smooth I went ahead and cut them out with a hobby knife.

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Using a syringe, I added Elmer's ProBond glue to complete the fin skins.

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After letting them dry... they turned out a lot better than I was expecting.

Time to move onto the inner fin piece and gluing everything together.
 
You get a chance come fly with the TriCities Rocketeers, we have quite a few west side folks come fly with us.
 
Me too, but I figured I’d give them a shot. Although I have been discussing maybe coating them in a layer of BSI epoxy after I form them. That should make them rock solid.
Balsa skins over plywood frames is amazingly strong. Estes used the same technique on the Mega Der Red Max, and I’ve flown it on 6 grain 29 mm motors quite a few times. Epoxy would make them more ding resistant, but wouldn’t add strength.
 
Me too, but I figured I’d give them a shot. Although I have been discussing maybe coating them in a layer of BSI epoxy after I form them. That should make them rock solid.

Papering fins with Titebond would work very well and is much easier to fix in case of a mistake

Balsa skins over plywood frames is amazingly strong. Estes used the same technique on the Mega Der Red Max, and I’ve flown it on 6 grain 29 mm motors quite a few times. Epoxy would make them more ding resistant, but wouldn’t add strength.

Question: Since he already has the balsa fins, would removing material from the field of each fin and then cover with 1/64"~1/32" aircraft ply bonded with epoxy or Titebond work as well?
 
Day 2:

I decided to finish the rest of the fins today. Started by sanding the middle ply of balsa fin using 220 grit sandpaper.

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Then I cut it out with my x-acto. Side note... I use a kitchen knife sharpener to keep my x-acto blade sharp without constantly having to replace them. Little technique I learned from cosplayers who constantly cut through blade dulling EVA foam.

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I then assembled the fins per the instructions... applying the balsa fins to each side of the thicker fin frame. The first one I used Elmer's ProBond on and the Loctite CA on the second to see which would work better. While they both seem sturdy enough, the CA was a lot easier to work with then the ProBond. I ended up using CA on the other 2 as well.

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Happy with the fins, I started using the coupler to trace some bulkheads into 1/8" thick basswood for the baffle.

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I slowly cut one out using an x-acto... not the easiest and cleanest method, but it got the job done.

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Next I'll probably round the leading edges on my fins and then work on the baffle coupler for a bit before I get back to epoxy coating my fins.
 
You get a chance come fly with the TriCities Rocketeers, we have quite a few west side folks come fly with us.

I might have to give it a try. I usually fly with Washington Aerospace Club https://www.washingtonaerospace.org/ at 60 Acres since it's 25 mins from my house, but they only have that field Jan - April. By the end of April they change the launches to their Mansfield site which is about 2 hours north of where you guys launch. Either one is a 3 and a 1/2 hour drive for me... one way. :eek:
 
I might have to give it a try. I usually fly with Washington Aerospace Club https://www.washingtonaerospace.org/ at 60 Acres since it's 25 mins from my house, but they only have that field Jan - April. By the end of April they change the launches to their Mansfield site which is about 2 hours north of where you guys launch. Either one is a 3 and a 1/2 hour drive for me... one way. :eek:

I understand how travel time goes, one good thing about our field we don't have a swamp and its almost all lawn (other than that darn cornfield a .5 mile away or so later in the summer). :)
 
Day 3:

I didn't get as much done as I wanted to today... but I did manage to finish turning the coupler into a baffle.

I started with my cutout bulkhead and figured out where I wanted to drill me some holes.

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Then I used a 1/4" bit to punch 8 holes into the bulkhead. I also drilled a hole for the shock chord eyelet and screwed it in.

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Sanded the bulkhead until it fit nicely inside the coupler.

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Then I attached it to the coupler and coated both sides of the bulkhead using my BSI 5-min Epoxy.

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I then cut out a second bulkhead and split that in half.

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I attached one of the halves to the center point of the coupler. I also coated the rear facing side in epoxy.

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After dry fitting the second half I wasn't happy with the gap it was leaving in the middle (my bulkhead was cut a tad bit small.) So I decided to add some more material to it. I cut a small piece of basswood for it.

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I glued it together using some Loctite CA.

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Then I installed that into the bottom of the coupler and coated it using the epoxy.

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Tomorrow I am hoping to work on the fins... finish shaping them and coating them in a bit of epoxy. Maybe I'll be able to start some spiral filling on the tubes too or work on the motor mount.
 
I wish Estes had done plywood through body fins. :(

Sent from my SM-G950U using Rocketry Forum mobile app

Not sure why the need for plywood. Rocket is intended to be light to fly on Estes recommended motors. The layered balsa fins will be plenty strong and should take reasonable composite motor power.
 
I'm with Joe Rice.... Unless you're planning to put WAY more motor into the model than it's designed for (Estes black powder E16s and F15s) there's no need to add all that weight. The same is true of that big eyescrew, but it's too late for that now. :)

I would have no problem flying one dead stock on a G80 - all wood glue, paper tri-fold shock cord mount and all. Now if you are thinking about a VMax or something, then beef ups would make sense. But all that weight makes the nice long, slow burning BP motors a less than optimum choice. Well, maybe I'd want to beef up the centering rings for a G80. But that's it.

Just as you fly your Star Orbiter on F15-8s, the SBB is just gorgeous on F15-6s and gets to about 900 feet.

The place to fly an SBB on a G is the TCR sod farm flying site, by the way.

The original SBB was a 24mm motor mount model.....
 
I'm with Joe Rice.... Unless you're planning to put WAY more motor into the model than it's designed for (Estes black powder E16s and F15s) there's no need to add all that weight. The same is true of that big eyescrew, but it's too late for that now.

I usually add weight to most of my rockets with little adverse effect. Even my Star Orbiter got a beefing up and has metal pieces inside of it adding weight. I guess after I finish the fin can I’ll go ahead and dry fit it, find the CG and pre-paint weight so I can test it on Rocksim and see how it performs. Then i’ll decide if I want to use a less robust coupler.
 
Real world data from our part of the country: Expect 550-600 feet on the E16-6 and 820-920 feet on F15-6. These are measured with either AltimeterThree or FireFly. My SBB was stock except for adding a baffle in the middle. No metal.

It’s past tense because I treed it on its sixth flight in early December and didn’t get the remains back until several weeks later....and you know what sort of weather we had then.

I have three kits on hand and will build one up soon - again stock except for some kind of baffle.

So - some figures to compare with your sims.
 
Not sure why the need for plywood. Rocket is intended to be light to fly on Estes recommended motors. The layered balsa fins will be plenty strong and should take reasonable composite motor power.
The layered fin design just seems like a lot of unnecessary work and I agree that on normal Estes motors you'll never have an issue. [emoji83] I would like to put an H-motor in there and let it roar. I like the nostalgia of the Super Big Bertha with a modern twist. Would this be called rocket Hot Rodding?

Sent from my SM-G950U using Rocketry Forum mobile app
 
The layered fin design just seems like a lot of unnecessary work and I agree that on normal Estes motors you'll never have an issue. [emoji83] I would like to put an H-motor in there and let it roar. I like the nostalgia of the Super Big Bertha with a modern twist. Would this be called rocket Hot Rodding?

Sent from my SM-G950U using Rocketry Forum mobile app

....with that objective, I would have to agree with a "hot rodding" approach to the build
 
The layered fin design just seems like a lot of unnecessary work and I agree that on normal Estes motors you'll never have an issue. [emoji83] I would like to put an H-motor in there and let it roar. I like the nostalgia of the Super Big Bertha with a modern twist. Would this be called rocket Hot Rodding?

Sent from my SM-G950U using Rocketry Forum mobile app
Part is the reason for the layers is to make a thicker fin so it’s a bit more scale to the std BB. So the inner frame is Balsa also? If it was ply, the system makes sense, and would take H motors no problem. With an inner frame of balsa, the tab would seem to be the weak point, but with good wood glue joints, I think it still would handle an H. I’ll build mine that way and find out!
 
Although I'm not recommending anyone fly this model with a motor larger then what is specified on the package I believe the fins would hold up just fine with larger motors. I do believe however the thin walled body tube would be the limiting factor in how much motor this model could fly on. Please post images of your before and after flights on any H size motor flight. I'd like to see if it returns in one piece or not.


John Boren
 
Although I'm not recommending anyone fly this model with a motor larger then what is specified on the package I believe the fins would hold up just fine with larger motors. I do believe however the thin walled body tube would be the limiting factor in how much motor this model could fly on. Please post images of your before and after flights on any H size motor flight. I'd like to see if it returns in one piece or not.


John Boren

Challenge accepted, John!

As mentioned in the other SBB thread from some time back, the 1/8" balsa stock fins on the original SBB and Broadsword held up to a lot more than people gave them credit for. To this day, I fly my bruised and beaten Broadsword on 24mm G's. Ellis G37's, Aerotech G55's; it just won't die!

I think the current built-up fin version will do just fine on several 29mm H motors. I look forward to trying it out this summer!
 
Day 4:

More fin work... sometimes I give my fins a proper airfoil and other times I just round the leading edge. It really depends on the rocket for me and I decided that this one would be better suited for a rounded leading edge and no taper at the back end.

So I marked my fins and placed some tape down so I know how far to sand.

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Then I used a sanding block to get the leading edge rounded.

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I try to get them to match each other... but don't usually stress it as it's hard to notice when they're spaced apart on the rocket. Looking good to me.

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Then I decided to finish them with a coating of slow cure epoxy... a technique I learned in one of the Facebook model rocketry groups I belong to. It toughens up the balsa, gives me a nice surface for paint and protects from dings and dents. So I made myself a little jig from a tube I had laying around to hold the fins.

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Then I used some BSI 30-min epoxy and spread it all over the fins, making sure I got the edges too, using a sponge brush. I did not do the tabs though... didn't want it cemented to my jig.

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After curing for 8 hours I pulled them off the jig.

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I then repeated the process on the attaching tabs. I'm pretty happy with the results on the cured portions; they feel rock solid.

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Now I'll let them sit for 24 hours to cure completely. Then I will sand the living daylights out of them until they are nice and smooth. They feel hard enough that I may need to pull out the palm sander. We'll see... :)
 
Day 5:

Didn't have much time today... but I finally finished prepping the fins. Sanded down the epoxy coating with 220 sandpaper on a block and some elbow grease. They turned out amazing, they feel extremely solid and super smooth.

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Next I decided to work on the body tubes and fill in the spirals. I use Elmer's WoodFiller.

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But first I knocked some of the shine off with 220 so the filler would have something grab to.

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Then using my finger I applied filler to the seams.I'll end up waiting until tomorrow to sand it all down.

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Next I decided I would start making myself some centering ring reinforcements... cutting the pieces out by hand.

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Then after browsing Apogee for a parachute and some rail buttons I realized that for fifty cents more I could pick up two plywood laser cut centering rings if I put my order in at BMS instead. So now I'll have to wait for those until I can get my motor mount started. Tomorrow I'll probably tackle sanding the tubes and cutting the fin slots.
 
Are you replacing the stock parachute with a nylon parachute? If so, which one did you purchase?

Nice work on your build! I'm looking forward to the next update and seeing the finished rocket. :)
 
Are you going to try an H-motor? With the quality of your construction I think it would work. Just not on a repeated basis.

Sent from my SM-G950U using Rocketry Forum mobile app

Some day I may... I do not currently have a Lvl 1 Cert. I do have a Madcow Big Fizz that I plan to turn into an over-sized Super Alpha and hopefully get my Lvl 1 with.

Are you replacing the stock parachute with a nylon parachute? If so, which one did you purchase?

Nice work on your build! I'm looking forward to the next update and seeing the finished rocket. :)

I am replacing it... I don't use plastic parachutes on any of my rockets. I just got a standard 24" nylon chute from BSM.
 
Day 6:

Was planning to sand the body tubes and cut some fin slots today... had about 2 hours of working time available. Turns out that the sanding took a lot longer than I had anticipated. I applied the filler pretty heavy handed on one of the tubes.

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They did turn out real nice and smooth though. Although half way to the process I was cursing my insistence on filling in the spirals... then I kept on reminding myself about how nice the paint job will look later.

Once I was done sanding, decided to dry fit the coupler, tubes and nose cone... cause why not.

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Tomorrow it's fin slots and then I have to wait for my centering rings to get in.
 
Those fins look beautiful, very nice work!

I just ordered one for my son to build in our school rocket club, we can't wait to get started. I am a little bit surprised that the airframe isn't slotted - I thought that was pretty much standard these days.
 
Day 7:

Today I decided on getting my bottom body tubes fin slots cut out. I went ahead and cut out the provided fin template from the foreign copy of the instructions... and to my surprise it did not completely wrap around the body tube. So I opted to go to PayloadBay.com and get my own custom made fin guide. Centered the body tube on the print out and marked my lines.

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I then used my angled aluminum to draw straight lines along the tube where my fine lines were marked. The concentric lines were drawn by using a clamp as a stop for the tube and slowly rotating it as my pencil stayed at rest on the edge of the angled aluminum.

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Following that, I used the angled aluminum as a guide for my x-acto and cut out the slots.

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Finally, I decided to dry fit the pieces I had completed.

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Centering rings, launch buttons and parachute should arrive Monday. There's not much else I can do on this thing until those arrive. Maybe attach the kevlar portion of my shock cord to the baffle.
 

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