Estes Black Brant XII Build Thread

[ljwilley]

I recently received an Estes Pro Series II Black Brant XII for a Christmas present. There are no build threads of this rocket on the forum yet, so I thought I would do one. Here is a picture of all the parts:

 

[ljwilley]

I would have liked to get plywood fins in this kit, but balsa is to expected with Estes- they are obsessed with balsa. Other than the fins and outer detail/conduits being balsa, they are nicely laser cut. I will be cutting out the rest of them and sanding them soon:

The plastic parts are also really nice--

I've already cut the slots in the lower plastic piece:

The next plastic piece, the part that connects the lower tube to the 2nd stage tube, also seems to be of high quality. I am impressed that Estes used so many plastic parts in this kit:

There is also the transition from the second stage to the third-


It also came with a big plastic nose cone, and yes, the whole thing is blow molded plastic! Estes doesn't usually do big plastic parts like this:

The tubes are also of good quality, as per normal with Estes. They actually used the same 29mm tube for both the motor mount and the upper stage tube. (The longer one is the body tube)


As normal for Estes pro series II rockets, the kit came with a nice nylon chute, 1/4" launch lugs, A plastic motor retainer, and the little green engine block ring. (Which I will not use because I never do)


It also came with the normal elastic shock cord + a Kevlar cord to use as an anchor. I have not seen Estes use Kevlar in their kits before, and I hope they will use it more in the future:

The kit also included cardstock centering rings and clay for nose weight. (I would rather plywood rings, but the cardstock ones work fine so I won't complain)


It also came with instructions:


There is one more part I really have to point out- The 3rd stage fins are injection molded. I was surprised to see how nice these upper stage fins were; they weren't 2 part and hollow like other plastic Estes fins, they already had the correct airfoil and detailing, and they had a really nice matte finish. They weren't so glossy you got smudges on them, and they weren't so rough they needed sanding! I am very pleased with these fins, I just wish the other fins on this rocket were the same!



I am going to be posting a lot of pictures in this build thread, which I have found to be helpful to me when looking at other build threads!

I hope someone learns something or is benefited by this thread!

 

[DigBaddy]

That green ring is not an engine block. You'll notice that in the instructions.

 

[ljwilley]

Oh yeah. But if did have one, I still wouldn't use it!

 

[ljwilley]

Got all of the pieces for the lower 4 fins cut out and sanded smooth. Yes, all of those go into just 4 fins! Going to glue them all together and then sand on the airfoil next. It is going to be a lot more sanding--

 

[ljwilley]

Just finished the airfoil on the fins. Was going to try to do the airfoil shown in the instructions but it turned out like this. Still looks cool, though.

 

[ljwilley]

Finished ALL FOUR!


And then I realized I had to do the same exact thing with the 4 second stage fins--

Here is the assembly to line up the centering rings before I glue them. (No I am not gluing this all together yet)

 

[ljwilley]

Here are all the parts for the second stage fins. Yes, they all make just 4 fins. The motor mound is also drying. I will be sanding and gluing and sanding and sanding and sanding next. Then I will reinforce the motor mount with more glue. And then I will probably find something else that I will have to sand and sand and sand.

 

[ljwilley]

2nd first stage fin is drying, working on gluing together the 2nd stage fins now.


I will need to do some epoxy fillets on these fins once this glue dries.

 

[ljwilley]

2 2nd stage fin sandwiches done:

 

[Art Upton]

2nd first stage fin is drying, working on gluing together the 2nd stage fins now.
View attachment 622321

I will need to do some epoxy fillets on these fins once this glue dries.

Why Epoxy? You don't need the strength, you can use clear silicon Tub & Tile sealer to fill the gaps light weight and you can remove it if you make a mistake.


I had no outside fillets on my L2 or L3 rocket, only internal glue. Same on an Estes 2.5" PSII rocket on an I205.

 

[ljwilley]

Don't have any fancy silicon sealer and I don't really care about weight. It's not exactly a "high performance" rocket. Also about:

You don't need the strength

You don't know me very well!

Either way I have plenty epoxy and I need to fill the gaps. I may not need the strength but weight isn't exactly an issue so I am okay with it.
I will use epoxy for this rocket.
I will look for the silicon sealer though, it is a good tip. Thanks!

 

[Art Upton]

I will use epoxy for this rocket.
I will look for the silicon sealer though, it is a good tip. Thanks!

I generally use it "after" it is painted, simply to keep air out of the gaps. But that is because most of my builds, even many LPR builds are fin can made outside of tube and painted tube cut to drop over the painted fin can.

Your rocket I would put it on before painting.

 

[neil_w]

Check out Chris Michielssen’s blog, he did a build on this rocket and there are many helpful tips there (including sanding the fins.

 

[ljwilley]

Your rocket I would put it on before painting.

yes

Check out Chris Michielssen’s blog, he did a build on this rocket and there are many helpful tips there (including sanding the fins.

Already sanded 2 of the second stage fins, so too late for that. But thanks, I will take a look!

 

[ljwilley]

First stage fins are all on, epoxy is on, Kevlar shock cord anchor is drying.

 

[Paul Howard]

Are you using a stiff/hard sanding block of some sort to sand your fins? One technique is draw lines parallel to the leading and trailing edges, sand to the line, re-draw more lines, sand more, etc and this helps a LOT, especially with airfoils on Wings, but works well for rocket fins also. Truthfully, the more curved airfoils you have are more aerodymically clean for the speed of this rocket than the more angular airfoils of the actual (and much higher speed) Black Brant. Cool project!

Finished ALL FOUR!
View attachment 622281

And then I realized I had to do the same exact thing with the 4 second stage fins--

Here is the assembly to line up the centering rings before I glue them. (No I am not gluing this all together yet)
View attachment 622283

 

[ljwilley]

I am using an orbital sander and turning it upside down. Not trying to do anything fancy, so as long as it looks cool it's fine with me. I do need to get a sanding block, though. Thanks for all the !

 

[jrap330]

I am using an orbital sander and turning it upside down. Not trying to do anything fancy, so as long as it looks cool it's fine with me. I do need to get a sanding block, though. Thanks for all the !

Gee, you are not afraid a power sander would take too much off, since it is balsa?

 

[neil_w]

I do need to get a sanding block, though. Thanks for all the !

Some sort of sanding block is really an essential tool. Often you can get away with just putting the sandpaper on the bench but there are plenty of times you need to hold it in your hand. The Estes Ultimate Sanding Bar appears to be a fairly direct copy of the late lamented Great Planes sander, and it's great. But you can get away with cheaper solutions if desired. I wish I had bought at least a couple more Great Planes sanders while they still existed.

 

[ljwilley]

Gee, you are not afraid a power sander would take too much off, since it is balsa?

You just have to go slow with it.

Some sort of sanding block is really an essential tool

Yes I know I need to get one I just keep forgetting about it. I will make sure to get one with my next parts order from apogee. The apogee one looks like higher quality and is also bigger. I don't order much Estes anymore. (other than kits)

 

[ecargmij]

Gee, you are not afraid a power sander would take too much off, since it is balsa?

I used a belt sander to do mine.. fine grit and light pressure checking very often.. saved my shoulders

 

[Joekeyo]

What grit did you use? Were you satisfied with the results? Would you please post a picture of the cross-section.

 

[ljwilley]

I used 400 grit sandpaper. I am ok with the results, but If I did it again I would get a sanding bar and sand off a straighter line like the real thing. As for a cross section I don't know what you mean- of the whole fin, the airfoil?

 

[ecargmij]

I used 400 grit sandpaper. I am ok with the results, but If I did it again I would get a sanding bar and sand off a straighter line like the real thing. As for a cross section I don't know what you mean- of the whole fin, the airfoil?

They were asking me, I can send pics in a private message as I don't want to hijack your build thread.. was just saying I also used a power tool.. I clamped my belt sander upside down in my bench vise so i could use both hands shaping the fins. I need to go look to see what the grit was.. you already showed a pic of your airfoil profile

 

[ljwilley]

you already showed a pic of your airfoil profile

Thats what I thought.

I can send pics in a private message as I don't want to hijack your build thread

I am always ok if anyone posts any pictures of their own build or posts their own comments especially if it is to help another TRF member. Anyone is free to post pictures of their own black brant XII if they want!

 

[ecargmij]

It's not perfect but I used the line in the skins as the break mark for each taper and tried for the same reveal on the fin core at the leading and trailing edges.. I didnt go super sharp.. I also bought an upgrade kit from bad boy rocketry on ebay with plywood centering rings and bass wood fin cores.... the belt on the sander was a used 120 grit

 

[ljwilley]

Just finished gluing on the small details for the upper stage:

 

[DigBaddy]

Nice work on those. I was lazy and whipped up designs in CAD for them and printed them. Less time than all the sanding

 

[ljwilley]

Nice work on those. I was lazy and whipped up designs in CAD for them and printed them. Less time than all the sanding

Smart! Didn't think of that. They actually did not take long to sand. The fins, on the other hand....