YABBTBT: Yet another Black Brant Twelve build thread

[DeltaVee]

So it seems a good 24-36 hour drying time is great for the filler primer. You can see the 29 mm calico looking tube there. On a close inspection it looks like after sanding most of the primer off I can get away with just applying the black/silver coat! I could put another coat of primer on it but I can live with barely visible spirals... and I'm fairly sure they'll be barely visible. Next to that is the stacked first/2nd stage parts which needed to be painted orange. When the coat was wet it looked like the surface of a sunkist navel (naval?) orange! Yuck! But as it has dried, it has started to look much better. I think it will get a bit better as it dries further (the coat is only an hour and a half old so far), and I think I can live with it even as it stands now. It won't be a absolute perfect paint job but I think it's reasonably satisfactory ;-)



Also down at the lower left on the blue board, you can see the final contoured hatch covers and wiring tunnel... they're ready for filling and so on. Once the orange paint dries a bit further I'll remove the last of the Tamiya masking tape. I cannot praise it more for it's ability to stretch and stick to a contour like a transition...

Well it'll be about 2 days before I can paint anything other than the 3rd stage body tube! That I can do later today.

 

[DeltaVee]

I was away all last week... I did paint the gray band on the 2nd/3rd stage transition gloss gray as per Peter Alway's drawing of the paint scheme. I also painted the 3rd stage 29 mm body tube black after a good sand down. The first coat of black was terrible and still showed a slight hint of a spiral... but it was so bad a surface that I had to sand it down... and the coat after that was phenomenal. ALMOST makes me want aggressively sand every first coat and do it again. The gloss on the 29mm tube is almost perfect. The good news is that the feared orange peel on the BT 60 second stage isn't bad at all...

So a week ago last Friday I did the black paint on the 29mm tube, and the gray section on the 2nd/3rd stage transition. also shown is what I just did moments ago, namely cover the balsa detail bits with CWF... I thinned it down a bit to the consistency of thin pancake batter (this stuff looks just like it... but I'm sure it wouldn't TASTE like it!), and used a small testors hobby paint brush to apply. I had them sitting on a paper towel to prevent it from seeping to the undersides while I held the part in place with a tooth pick so it wouldn't move while I brushed the stuff on. The picture below illustrates the current state of affairs.



Once the CWF is dried and sanded, I'll give the detail parts a shot of filler primer.

So I still have yet to paint more black parts i.e. the 3rd stage fins (black with yellow attachment plates), and the hatch covers. More than likely, I will attack the silver sections next (tomorrow or the day after). One downside to painting the tube prior to handling the details is it'll be somewhat more difficult to place the detail bits since I'd rather not draw lines on the finished tube. I'll likely use tape to line things up... The todo list also includes finding a suitable light blue for the tunnel... I'll also need some flat gray for the antenna band on the 4th stage but perhaps I'll let that slide.

 

[DeltaVee]

Sanding the detail parts went quickly and now they're covered in filler primer:


The good news is a) hardly any grain shows thru meaning b) there'll be none when I finish sanding these. I will say sanding down the hatch covers is a pain due to their small size.

I've also started the silver bits ( well I used rusto 2x metallic aluminum... it's actually quite decent for rusto paint!). I was trying to figure out a good way to place tape on the 3rd/4th stage parts so that I can get a good mask line and more importantly properly place the detailed parts. I have several of these "green rings" for 29mm tubing you get with your PS II kits. It's a very tight fit usually so I shaved of one inside layer and voi la:




I used on the 29 mm tube and on the 4th stage nose section to place the tamiya tape perfectly straight on the tube(s)! It'll be silver (er, metallic aluminum) forward of the white tape. (photos to come) This will also come in handy as I can use this to place tape on the tube to mark where the detail parts will go (at least for along the tube). I'll run a strip of tape lengthwise for the lateral placement. No pencil marks required.

 

[DeltaVee]

So all of the metallic sections are now painted... The black portion on the 1st/2nd stage transition will have to wait a few days for the metallic aluminum paint to dry... I'll be able to sand the detail parts smoothe tomorrow, so as far as painting goes, there's the brown band at the bottom of the 3rd stage tube, and remaining black hatch covers. The wiring tunnel is supposedly light blue... plus that not-yet-decided grey antenna band on the 4th stage. Here are the silver bits:



This is all a few minutes old. Everything except the 1st/second stage got unmasked (this metallic aluminum stuff by rusto sets up VERY quickly compared to much of the 2x line... but I'm still going to wait a few days before I paint the black band on the 1st stage). As you can see if you zoom in on the shot, the metallic aluminum gives a very nice sheen. I used that also on my Estes Little Joe I and it worked pretty well.

The photo resolution is also high enough to show a few small "plotches"... It's rare when I don't get those when using rattle can paints unfortunately. Most are very small at least.

 

[DeltaVee]

So yesterday I painted the hatch covers, side one of the fins black while giving the metallic aluminum paint another 24 hours to cure. The tabs on the plastic fins are fairly small and I wanted to protect them from overspray. Since they are plastic I broke out the good ole' micromask. It's water based so you would not use this on anything porous I should think. This, for example, is how I kept the root edges of my 2037 D-Region Tomahawk clean as well. In the photo I had just gobbed on a bunch of it being careful to keep it only on the root side of the fin!



A shot of black paint on the taped down hatch covers and fins... after sanding the balsa details are nice and smooth so it was time:



Hard to see at this size! The opposite sides of the fins were pretty clean but I got paint on the micromasked root edges tho! The next day (today) I did the black band on the first stage and side 2 of the fins... yes I didn't wait 48 hours but since side 2 was pretty clean I thought I could risk it. I should have hit the fins with primer first because the coat isn't as smooth as it could be. I could sand them down and drop another coat of paint on it but it's still reasonably glossy and enough is enough. Here is the result:



The upper set of fins show the raw finish... the lower two show the micromask peeled and in the process of being peeled off. Nearly clean as a whistle... and it even comes out of the holes in that are in the tabs!

At this point I've decided to forego the yellow root fin pads and the gray antenna band... I'm still on the fence about the brown band at the bottom of the 3rd stage tube. Oh yeah and I need to attach the launch lugs... scraping paint... oh boy I can't wait! I guess I'll have to get used to it since I'll need to do the same for the detail parts too!! You can also see in the photo above the white paper towel, the rail guides I'm intending on attaching to the first stage tube. The pad is just (I think) enough (I'm sure) to avoid rail rash at least. I will likely scribe away the paint and the outermost layer of tube and epoxy these on... I've done this before with my AT HV-Arcas and AT Astrobee D to good effect. I had gotten a pack of something like 5 of these 3-d printed rail guides that were 2-3" long. I cut them in my xacto mitre box to manageable lengths. The ones shown are the last of 'em and evidently the vendor now sells them in small 1" pairs for the same price I got the 5+ 3" long ones. So it goes!

Well there is only one thing left to paint and that's the wiring tunnel so I'll have to find some light blue for the chore. Its surface also came out quite nicely. This won't take too much time and I'll be able to commence final assembly in a few days (or sooner if the mood moves me to do so).

 

[DeltaVee]

So how do you take one of your better paint jobs and try to muss it all up.... well one way is to cut thru the paint to attach launch lugs. Since I had done the paint job already this was a kind of pain to line up and get right... I used a strip of paper around the tail to get the distance between the seams and the distance between the slots. I transfered that to a wide paper guide and used the still visible plastic seams on the tail get the alignment line centered. The most difficult part was dealing with the friction between the paper guide and the paint. It didn't slide easily, but since this isn't a full wraparound guide, I only needed to have it on half the tube.



So here it is with one position readied. A similar patch was carved out just behind the black to the left. Once I finished mutilating (it definitely pains me to cut into a nice finish) the first stage, a dab or two of 30 minute epoxy....



A reasonably straight 3/16" dowell helps keep the alignment although very likely not needed... No matter how carefully you cut, there'll always be some play in how snugly the guides fit the carved out section... don't want any potential rotation of the guides while the glue dries. I've used this technique on many rockets including my AT HV-ARCAS which was fitted with the original square lugs. Changing to these really made a difference though.

The only caveat with guides like this is you have to take a bit of care when loading it on a rail because a good twist on the first lug and it'll come off unless you secure it with additional means i.e. screws or something. Since in my haste I glued the first stage together, I no longer had a good option when it came to screws ( I like to back buttons up with a t-nut if I can).

In case you're wondering about the "guide" as described:



Once the items marked "seam" are lined up with the seams on the tailcone, the long line (which spans the tube) is used to mark lightly in pencil the centerline marks. The guides are place on the tube and the dowell was used to align them where I could trace out each one's footprint for the final cuts. One more detail is that if I had sanded off the seam on the tail section I *could not* have gotten away with this so easily (or precisely!). I realized these seams are hidden unter fins so I just did not bother to take the seam off of the tail section. I DID however do that for the transition which is why the guide I made spanned the entire tube.

 

[DeltaVee]

Since I was in a paint scraping mood, I continued on with the very pesky hatch cover details. I started with the 4th stage/nosecone which is plastic... I tricked up a guide using "diagram 3" from the instructions. This allows me to slide it onto the tube for proper lower end placement of the covers. I started by holding a cover in its final location and adding tape to either side as a sort of "fence". I then started to scape a strip clean down the middle:







Spoiler alert.... this is VASTLY easier on the plastic than on the cardboard tube!



A bit of scoring on the plastic will give the epoxy something to hang onto. I used BSI 5 minute for this. It's amazing to me how much more this stuff stinks than the 30 minute stuff!



Application of the epoxy with a q-tip. Turns out that I did a good fit on this, so only a minimal amount is needed.

Once the upper section was done, the 29mm cardboard tube gets the same treatment:



Not quite done scraping, but I gave it the same sort of scoring as well. The scraping was harder for me to control
on the cardboard tube for some reason. Not much new here... one detail was prior to peeling the tape off and removing
my guide, I checked the alignment of the parts using an aluminum angle to ensure they were straight. It also happens
that I applied just a tiny bit too much epoxy on the carboard tube because I managed to squeeze some out which necessitated
removal of all my tape/guide so as to NOT glue them to the tube!

So here is the result... also not too easy to see:



You can see in the background on the left that I've dry fitted the 3rd stage fins. I'll likely use plastruct on the inside to fix them in place.

I still haven't obtained the right paint for the wiring tunnel. Scraping paint for that promises to be a royal PITA if these small parts are any indication. In any event I think that'll be it for this today.

 

[DeltaVee]

So looking for cheap light blue paint, I found what I thought might suffice in a can of rusto 2x... "spa blue"! I fail to understand why they can't just call it light blue. The cap color would be perfect, but frankly it's a few shades darker than I would've liked - I realize the cap colors are a joke! I'm getting close to final assembly so that is motivating me into making a few blunders... most recently attaching the aramid fibre shock cord mount before attaching the second stage fins precluding me from adding the epoxy to the inside!!! Not what I wanted but it really matters little. If I start breaking fins off then it's off to boyce aerospace for their 3d printed ones! Like I said the blue is a bit bluer that I would like but I'm just going with it on the wiring tunnel:



Of course the first coat was yesterday and it was hot an breezy.... I got a nice pebble finish on it so I sanded it all down... another coat will go on tomorrow am while it's still cool and quiet outside! The 3rd stage tube (if you open the photo in zoom in will show the scribe lines I put onto it to do the paint scraping.

This morning I was thinking about 1st stage fin attachment and how to guarantee a) the fins as snugly on the tube as possible and b) how to keep 'em straight. I flashed on using that fairly straight 3/16th dowel and a not too tight but tight enough rubber band (I'm planning on epoxy here so keeping things straight and snug are paramount - this is shown in Chris Michielsson's blog for the 2nd stage fins and it seemed reasonable to apply it here). You can see it in the above photo and close up below:


From above it looks pretty good and with the right elastic, once the first two are dry, I should be able to play the same game for the last two. I think this will work better than the paper template supplied in the instructions, or my Estes fin alignment guide (due to the extreme bevels on the fins).

Added: if you go this route with clothes pins... Slip a fold of paper over the trailing edge of the fin... Even with the fins sealed and painted, the pins might still be strong enough to add a miniscule dent to the surface.

 

[DeltaVee]

First set of fins glued on, epoxy cured... added the second set:



The red fin is to the left of the launching lugs when viewed from the opposite side from the lugs... photos of it on the tower show it that way so at least that's one thing I didn't mess up on!

Overall, this trick worked extremely well... better than I thought it would, anyway! The fins are near perfect. I substituted strips of balsa against the fins... the paper strips were not enough to prevent denting from the clothespins or the dowell... I highly recommend anyone trying this to place strips of thin balsa on each side of the fin prior to clamping them down. This just now reminded me of the real reason why I don't like balsa all that much! The first set of glued on fins provide additional tension to the rubber band so I opted for a slightly more slack one than when doing the first two fins.

I then went ahead and cemented the third stage fins in place... plastruct to the interior. Don't do any glueing that will prevent you from accessing the fins tabs! As I stated I blundered when I added the shock cord mount prior to gluing the second stage fins in place!

Inside... Plastruct to the rescue:


Yes I did in fact paint the brown band into place. I'm not sure it really goes there (it's where Chris Michielsson put it, so me too) or on the tube above that. Hard to know absolutely even with the photos I'm not too sure.

 

[DeltaVee]

I'm pretty tired today so I had resolved not to work on the BB XII... that lasted about 20 seconds. I was busy throughout the day so I decided to carry on at around 8:50 EDT this evening. Started by doing the first two opposite side 2nd stage fins:



I could not get away with what I did on the 1st stage fins obviously, and I was cursing myself for putting in the aramid shock cord mount as it cut off access to the tabs. The technique is from Chris Michielsson's blog but the photo he has implies one fin at a time... maybe maybe not. So I had to stuff epoxy into the slot and I VERY lightly put some on the fin tab and more on the fin tab root edge and put it in. The yellow fin was loose and fell out almost immediately when I tried to start applying the red fin on the opposite side. I figured the epoxy would take enough time to set so that once I got the rubber band on I could dicker around with it until I got the alignment right. It took a good amount of time to get a satisfactory alignment... I'm sure it's not 100% because you have to eyeball it. I did the best I could and it seems to be pretty good. The key factor in being able to get it right is TIME. Under NO circumstances should you use 5 minute epoxy for this (IMHO)... use 30 minute slow cure. It took two minutes just to get the glue in the slots and the fins put on. It took me AT LEAST 5 minutes of tweaking the rubber band to get the alignment to the point I could live with it.

Now that the first two fins are curing, I went on to scraping the paint for the wiring tunnel:


Notice I used the back side of my #1 knife blade. The scribe lines I put in are 1/8th" apart for the 3/16th" width of the dowell. For this job I opted for tite-bond. The reason is I can clean any glue that squeezes out with a damp paper towell. No worries about marring the tube with water, the black is about as glossy as I've ever gotten a paint job. Rusto 2x black is pretty decent although it can bite you.

Here is a pic of the "light blue" (HA!) wiring tunnel in it's final place:



Like I said, it's not BLUE blue... it *is* a lighter shade but I'm not sure I'd call it light blue LOL. The good news seems to be that the tite-bond has really grabbed and maybe this WON'T fly off on launch!


So at this point I've got:
two more fins to apply
Fillet first stage fin tabs and close up the back end
glue tubes to their respective transitions
finish recovery system
balance with the clay or perhaps something heavier. Something tells me I'm not going to fly this on a G80 but I might go for an F25

Except for doing the last two fins, I guess the hard stuff is pretty much done!

 

[DeltaVee]

Tonight the last two fins are now in place, epoxy curing.



I found these more difficult to deal with, in particular the root edges didn't lie flat on the 2nd stage tail cone. It was a bit frustrating but there wasn't much I could do to remedy the issue. With the extra epoxy I attached the 2nd stage tube to the stage 1/2 transition and the 3rd stage tube to the stage 2/3 transition. With the epoxy still curing I could not resist stacking the components:



Just a few things left to do at this point... it'll be ready to fly by the next CMASS launch this coming Saturday (weather permitting of course).

This rates as one of the toughest build/finish jobs I've done, EVER. There are still plenty of flaws, but it was a very satisfying build... one which I'm not too keen to repeat anytime soon! The old K36 Saturn V pales in comparison! At least that had basically two colors to worry about!! This will be FAR FAR easier with the 3d printed fins, but if you go all out, do the details, and all the painting, it'll still be a challenge.

 

[MALBAR 70]

Beautiful work as always John. Can't wait to see it in person.

 

[DeltaVee]

Beautiful work as always John. Can't wait to see it in person.

Thanks Mike, it's appreciated! This is the 4th rocket I've built since January and it took the longest. After a small break, I'm thinking my next project just might just be a 4" Estes Citation Patriot Upscale to complement my 3" upscale

 

[DeltaVee]

Only one thing left to do now....

So here it is, all more or less joined together, clay jammed into the nose, sitting next to my recently repaired Cherokee G...



That one thing left to do is to glue the fourth stage to the third. (nose cone section) If I had one more square of clay I *might* put it in but the entire thing w/o motor in place comes to 12.5 oz right now! A touch heavier perhaps than planned. It actually helps the more powerful F motors coast to a slightly higher altitude (according to the sim...) Apogee has a rocksim file that openrocket reads. Beware however because the forward section is 8.5" too short... they didn't account for the two piece 29mm section it seems.

Looking at it closely there are probably a few things I might have done differently... the one thing that stands out in my mind is I probably would have attached the 2nd stage fins (with the same rubber band compression) one at a time rather than two at a time. Doing it the way I did it allows for too much interference with the alignment of fin 1 when you're trying to adjust fin 2. I think overall it's probably better to do one at a time.

At any rate, I'm calling it done... this was a fun and intriguing project, kept me out of trouble for a few weeks at least!

 

[Huxter]

Love it! Thanks for the posts and advise - they will be used on my BBXll build!

 

[DeltaVee]

Love it! Thanks for the posts and advise - they will be used on my BBXll build!

Your welcome @Huxter

This really was (in spite of the setbacks) a fun build. I often think about getting a second kit of subjects such as this, so that I can "do it right" the next time! Usually it never happens! If I were to do it again, I would probably opt for the 3d printed fins by Boyce.... my workbench is still covered in balsa dust!

 

[DeltaVee]

Well I *thought* my next entry would be a "flight report" sort of thing. Turns out it's a case study in carelessness... namely, MINE!
The following diatribe is so you don't make this same blunder!

Truth be told, this matters little in the overall scheme of things but when you're doing a scale model, you'd like to produce an exacting replica of the real thing, right? You'd rather not "shank it" after a $90 expenditure, wouldn't you? A CMASS colleague of mine sent me an exquisite series of photos of the BB XII. I also found in flickr, Peter Alway's drawings. These I've had in my possession prior to final construction.

This drawing on page 11 of the BB XII instructions show this:



As you can see in the Alway drawing, the wiring tunnel is to the left of one of the hatch covers and just to the left of one of the fins. Peter's drawing has this detail inset:



And from one of the high-res photos:



The BEST part was when I carefully examined the box cover photo, the wiring tunnel MATCHED the photo, not the instruction drawings. I should have *known* not to trust something drawn but all of the drawings on pages 9/10/11 show the conduit on the wrong side of the hatch cover.

So the deed is done, it is what it is, so it goes... and any other platitude you'd care to mention. SO.... when you go to the marking guide on page 9 to mark up the positions of the conduit, and hatch covers, the end of the tube that is in contact with the diagram should be regarded as the TOP of the tube, since once you flip the tube over, the wiring tunnel marking will be to the RIGHT of the hatch cover.

Hopefully folks following this thread will A) already know this B) be more observant than me or C) have not gotten to this stage yet and will benefit from this screed! LOL

 

[Huxter]

Thanks for mentioning that! I will take heedence!