Estes Super Big Bertha re-boot

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Heh, Im sure slotting fins isn't too bad, it's just sorta one of those "but why?" kinda things.

However, that said, with this rocket coming with a guide on how to do that, it means I'll learn something new. I've been kicking around the idea of a scratch build or heavily modified Der Red Max with TTW fins.....


Not a bad idea learning how. My technique for slotting lightweight tubes is to draw the slot using an aluminum angle then use blue masking tape to outline the long edges and using light cuts with a new xacto blade its easy to follow the edge of the tape.

One reason Estes may not slot the tube is that the LPR tudes are easy to damage in shipping and even easier when slotted to damage.
 
Heh, Im sure slotting fins isn't too bad, it's just sorta one of those "but why?" kinda things.

However, that said, with this rocket coming with a guide on how to do that, it means I'll learn something new. I've been kicking around the idea of a scratch build or heavily modified Der Red Max with TTW fins.....

It's a good skill to have. I have slotted my own tubes on several of my scratchbuilds. The new Estes Shuttle also has you slot fin tubes. Really not a big deal.
 
What's the diameter on this, BT-80?

Also make sure the tube slotting guide is accurate. The one that came with the Scion was a tad off.
 
What's the diameter on this, BT-80?

Also make sure the tube slotting guide is accurate. The one that came with the Scion was a tad off.

Good to know. I generally don't check Estes guides...but will from now on!
 
Does anyone know what the thickness is of the layered balsa fin sets? Perhaps the same as the Mega Mosquito?
I know the original one piece, surface mount fins were 3/16" and had support strips on both sides at the root edge.

.

I don’t know about the 2000 re-release, but mine came with 1/8” fins. I left off the supports and used epoxy rivets and thixotropic epoxy fillets instead.


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If I remember correctly, each layer is about 3/32 inch thick - yes, like the big Mosquito. I'd give you more specifics, but as I noted above, my built model is hanging in a tree right now and out of reach for measuring.

Added later: I was in the hobby room earlier today and found the SBB fin sheet scraps. What they are is a generous 1/8 inch core with 1/16 inch sheets on the outside. So slightly thinner than if they were three layers of 3/32....but with thicker fin tabs.
 
Some great advice up there, y'all! (On my phone and quoting is difficult) Thanks!

I can't wait for this stupid thing...
 
Some great advice up there, y'all! (On my phone and quoting is difficult) Thanks!

I can't wait for this stupid thing...

If antsy, I believe the nosecone is already out there. Do a motor mount and cut some fins. I suspect a Rocksim file is out there and that would make it even easier. I built one 12 years ago and flew the daylights out of it. Stupidhead here didn't know
what he was doing and did surface mount 1/4" balsa wood fins! I had a lot of repair work with that thing and eventually it was weighed down so much I chose the wrong delay and it slammed the ground. The nosecone, upper tube and coupler survived
very nicely and I keep saying I'm going to bulid a new "more modern" sustainer for it. I'll append a picture later tonight of the surviving part when I get out of work. The nosecone is removable so technically I could
add some electronics with a little ingenuity.

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I'd suggest plywood TTW fins and if doing a DIY job use BMS (https://www.balsamachining.com/) thicker bodytubes. Get a retainer so you could fly HPR 29's (or 38's) with it and with all that room, could go with electronics and of course a Jolly Logic Chute release if keeping it simpler with "pseudo" dual deploy.

One other admission of stupidness. I put a motor block in there that limited my motor length and used an Aero-pac retainer. The rocket might have survived if I had been able to use higher impulse motors after it gained weight from all the fin repairs and additional paint. I was able to salvage the Aero-pac and use it on my L1 rocket. Cardboard and epoxy is easier to clean out than spiral wound fiberglass and epoxy. Kurt
 
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Hey I posted an OpenRocket file for a 38mm power version up higher in the thread. I haven't quite decided how to do the fins to mimic the fairly thick originals, but leaning toward a doorskin plywood core laminated with 1/32" aircraft ply and then glassed with ~2 oz cloth. It needs to be uber-strong as our flying fields are very unforgiving. It's definitely going to have the heavy wall BT-80.
 
Wooooo!!!!! This is going to be a very expensive weekend for me. Chute release, couple of parachutes, a 29mm aerotech casing (they're back in stock!), maybe a T3. At least I've got a nasty cold on top of spending all my money!
 
GUESS WHAT NERDS!!!!!!

It's on the Estes Website for purchase!!!!

Could not resist. I just ordered one, thought I already have a few high and mid power builds already in progress. The video made me do it :smile:
 
Dude awesome, I have one as well that my dad tried to throw away because he broke one damn fin on it..... I repainted mine silver. In fact it's the rocket that I have in my profile pic. I lost the original nose cone from a separation, so I put a nose cone I found in a box in our garage on it, giving it a unique, more arrow like look to it. I named it silver surfer. You got a pic of your model? I have one on my page of you wish to check it out, it won't allow me to upload a pic to my reply for some reason.
 
Umm, be aware this thing still uses the infamous paper centering rings so if proposing to use motors outside the range posted on the box, it's time to consider beefing up the motor mount. I'm going to use mine to reverse-engineer something a little more
robust and DD plus use this "stock" Estes one for MPR. I need to build a sustainer/fincan for that top end shown in msg #39 above. Kurt
 
Umm, be aware this thing still uses the infamous paper centering rings so if proposing to use motors outside the range posted on the box, it's time to consider beefing up the motor mount.

Yes, but remember that the 1/8 inch thick center ply of the fins goes to the motor mount tube as well, which will give MUCH more support than just cardstock centering rings (quantity 3). One could even temporarily leave out the aft ring so that one could fillet the fin tab-to-motor tube joint if desired.
 
Git er done. I got my kit but too many projects ahead of it. Lets watch your build.....


My 12-year-old son recently built a Baby Bertha, and gave the correct response of “Yes!” when I asked if he wanted to hot-rod it with an 18mm engine. I told him that we needed to model it for stability and see if we really gained much altitude with the larger engine given all the extra weight. As a result, it was a good teaching opportunity with modeling different scenarios in OpenRocket for performance and stability. I considered it a score to have his rapt attention for the better part of an hour given that no TV or video game was involved. We successfully test flew with an A engine in the front yard and then later with a C6-5 at a high-power launch.

All of which is to say that when I saw the Super Big Bertha listed, I knew it was a logical follow-up rocket for him, ordered as soon as it was available, and he would up getting it as a late Christmas present. For once, I remembered to take build photos and will post them in the next day or two. The rocket is currently getting painted in preparation for a high-power launch site in two weeks.

Andrew
 
My 12-year-old son recently built a Baby Bertha, and gave the correct response of “Yes!” when I asked if he wanted to hot-rod it with an 18mm engine. I told him that we needed to model it for stability and see if we really gained much altitude with the larger engine given all the extra weight. As a result, it was a good teaching opportunity with modeling different scenarios in OpenRocket for performance and stability. I considered it a score to have his rapt attention for the better part of an hour given that no TV or video game was involved. We successfully test flew with an A engine in the front yard and then later with a C6-5 at a high-power launch.

All of which is to say that when I saw the Super Big Bertha listed, I knew it was a logical follow-up rocket for him, ordered as soon as it was available, and he would up getting it as a late Christmas present. For once, I remembered to take build photos and will post them in the next day or two. The rocket is currently getting painted in preparation for a high-power launch site in two weeks.

Andrew

Very Kool! Don't forget to post pics of the flight(s).
 
Built a SBB clone from original plans about a year ago, with 24mm mount. Engine CATO'd at ignition and blew a hole out the side of the rocket. When I heard about this reissue, I couldn't wait so decided to make a clone last month with 29mm mount, TTW plywood fins, plywood centering rings, and thick walled tubes. Decals were from Sticker Shock. Finished weight is considerably more than the reissue, so BP Ds are out of the question. Minimum composite Fs and Gs. Wind has not been cooperating the past few weekends, so have not had a chance to launch. But it sure makes a pretty shelf queen.




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My 12-year-old son recently built a Baby Bertha, and gave the correct response of “Yes!” when I asked if he wanted to hot-rod it with an 18mm engine. I told him that we needed to model it for stability and see if we really gained much altitude with the larger engine given all the extra weight. As a result, it was a good teaching opportunity with modeling different scenarios in OpenRocket for performance and stability. I considered it a score to have his rapt attention for the better part of an hour given that no TV or video game was involved. We successfully test flew with an A engine in the front yard and then later with a C6-5 at a high-power launch.

All of which is to say that when I saw the Super Big Bertha listed, I knew it was a logical follow-up rocket for him, ordered as soon as it was available, and he would up getting it as a late Christmas present. For once, I remembered to take build photos and will post them in the next day or two. The rocket is currently getting painted in preparation for a high-power launch site in two weeks.

Andrew


As someone noted in an earlier post, the centering rings are cardboard and are on the thin side. The center ring is notched to accept the fins. If you've ever built the Der Mega Red Max, this fin structure will look familiar. The center layer is 1/8" thick with cutouts and 1/16" fay sheets. In order to prevent any warping, we used epoxy instead of wood glue to do the fin laminates. My work surface is left-over scraps of genuine imitation wood flood laminate. The underside is very smooth and flat. They are also just heavy enough that I can also lay another piece on top of the fins to keep things pressed together while the glue cures; I put wax paper on either side of the laminate to prevent sticking. And while I keep referring to myself, I was mostly hands-off, letting my son do the build. After the fins had all cured, he started hand sanding the edges flush since the different layers aren't all exactly the same size. However, the squeezed-out epoxy is hard, so we took the fins to the belt sander and with a very light touch had all the edges flat and true within a few minutes. SBB3.JPGSBB4.JPG
 
I am a bit puzzled, I was under the impression that the baby bertha came with an 18mm motor mount stock(that's what their website says) has Estes changed that?
Rex
 
I am a bit puzzled, I was under the impression that the baby bertha came with an 18mm motor mount stock(that's what their website says) has Estes changed that?
Rex

That's how mine came...

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if one wanted to lose a baby bertha...a D10 should help (a D21 probably will not shred it, the baby b is a tough bird) :).
Rex
 
As noted before, the body tube is not slotted. The instructions come with a fin and slot template, which I wrapped around the tube and lightly cut with a new x-acto blade. With the cut lines scratched into the surface of the tube, I pulled the template off and cut out the slots using a metal straightedge held along the body tube. With that done, the fins were inserted and glued with wood glue. If warping is a concern or I'm joining plastic, I use epoxy, but otherwise we assemble everything with carpenters glue. A wooden dowel helped ensure that the launch lugs were aligned. After all the fin work was done, the rest was very straight-forward: glue in the coupler and the shock cord, and epoxy the motor retainer on the bottom. E and F engines are what Estes specifies, but they didn't include a motor block (that I saw), so either put one in or be ready to wrap some masking tape around the engines.

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Tape wrap! Motor blocks are limiting and overrsted. 1/4"strip at the back with a half inch strip over that will jam it in the tube no problem.

I'll do tape wrap on any straight motor if it means I can stick a 3 grain Pro29 up the aft the next day!
 
E and F engines are what Estes specifies, but they didn't include a motor block (that I saw), so either put one in or be ready to wrap some masking tape around the engines.

The instructions have you make a masking tape thrust ring (see bottom of page 5). It works just fine.

Yeah, someday a 3 grain Pro-29. I wonder about the Mellow......:grin:
 
Yeah, the practice nowadays is to leave the thrust ring out so that you can fly the full range (i.e. lengths) of 29mm motors. Composites have the thrust ring built into the aft of the motor. Estes black powder motors need to have a narrow strip of tape wrapped around the end to act as the aft thrust ring. Engine retention can be done by wrapping a strip of masking tape around the end of the motor tube and engine. This makes for easier removal than friction fitting tape around the body of the engine and tightly fitting it in the motor tube. No pliers needed. You would think that the force of the ejection charge would blow the motor out if it's held in place by only a couple of wraps of tape, but it works. Took me a while to accept that, old school BAR that I am. So I'm ready to put in that 29-360 casing.
 
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