Build thread: Blackfish

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I prefer to think of it as the back side of the cabinet.

I remember reading that on some early computer model, he had the engineers re-layout the circuit boards, because he didn't find the traces aesthetic enough. Most customers will never admire the routing of their computer circuitry, but it mattered to him. (I don't know if this is apocryphal, or true).
 
I remember reading that on some early computer model, he had the engineers re-layout the circuit boards, because he didn't find the traces aesthetic enough. Most customers will never admire the routing of their computer circuitry, but it mattered to him. (I don't know if this is apocryphal, or true).
True.
 
if you can't be happy and productive, pick one. And I'll add that sometimes the other miraculously follows.

(catching up on past posts)

That is good advice. I've done next to zero rocketry related activities lately, partly drowning in the news, partly because Red Glare was cancelled (saw that coming), and remainder just because balancing home life / work / health has been a delicate dance lately.

Oh well, I've ordered a pile of LPR Estes and Quest motors that will be well suited to our local parks where appropriate social distancing can accommodate some rocket launches.

Plus watching the Blackfish come together, and enjoying the rag-chewing that always accompanies your build threads.
 
Want the glue to adhere to fresh wood, not char.
I've never had a problem with this after quite a few fin roots and a few centering rings glued on or in without sanding off the char. It's a very thin layer, thinner than the wood glue penetrates, and very well adhered to the wood beneath. It's really not an issue, I believe.
I have enough trouble making the OUTside of my rockets look decent, I don’t sweat the innards
Hear hear. ;)
I remember reading that on some early computer model, he had the engineers re-layout the circuit boards, because he didn't find the traces aesthetic enough. Most customers will never admire the routing of their computer circuitry, but it mattered to him. (I don't know if this is apocryphal, or true).
I would be unimpressed by driving up the cost by imposing the extra demand of utterly irrelevant aesthetics. Such a demand might even compromise function by, say, needlessly lengthening paths or reducing the separation of signals. But those probably weren't factors on Jobs's early efforts. Still, adding pointless requirements into the mix is bad engineering.

Mind you, I'm not saying that aesthetics are never important; if I believed that I'd never paint a rocket. Certainly the look of a thing matters - sometimes. Sometimes it's even worth compromising other factors up to a point for the sake of looks. But to compromise something else for the sake of unseen looks? No.
Did anyone follow my link? It’s one of my favorite Steve Jobs quotes, quite apropos.
I tried to follow the link but got a text-only page without anything apparently Steve Jobs related. I don't like to see naked particle board on the back of a cabinet. But I'd rather that than hidden particle board, because at least then I'd know to pass it by and get a better cabinet.

EDIT: I scrolled way down and found the quote. And it's no wonder that iPhones look better than they perform. I see now that it's about plywood, not particle board, which is very different. And a chest of drawers is different from a cabinet, at least the kitchen cabinet that I assumed, since a kitchen cabinet is never moved around so the back is never seen, where the back of a chest of drawers is seen occasionally.

So, I'd still use good quality plywood for the back, as it is both less expensive and more dimensionally stable than the beautiful hardwood that the rest is made from. I'd save the expensive, beautiful hardwood for where it matters, the visible parts of the next piece of furniture that I make. Because people move chests of drawers and occasionally see their backs, I might use oak veneer plywood.

(Jobs always was the image fellow. I wonder what The Woz would pick for the back.)
 
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Yes. But I *have* been curious to experiment with thinned epoxy as an alternative to CA for hardening nose cones. Wouldn't commit it to critical part until I had worked out the process.


If I confirm that the JLCR would work OK in a BT60 (it is made to) then I would probably try to use it for E flight, which should be over 1000'. For Ds or below it's probably not appropriate.

Hello - I just found this thread and wanted to say I think the design and color scheme are amazing! I'm looking forward to hearing about it's first flight with hopefully some pictures/video.

I also wanted to chime in with another vote for the JLCR - this is exactly one of the applications it was designed for. I have used a JLCR multiple times in BT60 rockets, and have never had a problem. If you're in any way hesitant, I recommend doing what I did: get an "expendable" BT60 rocket and fly the snot out of it with a chute release. Abuse it. Fly it like a rental. I used an Estes Firebolt. It's big and heavy and flies between 340-815 feet depending on motor choice. That keeps it low enough to see whats happening at ejection and follow it all the way down. It's also low enough that if something goes wrong, oh well. If the chute slips out due to wrong packing, it won't drift too far. If the chute never opens, well, that's why you experiment on a test mule. Make a handful of flights with it setting the release altitude one step lower each time. That will tell you how your parachute material/design/packing style responds and how long (in feet fallen) it takes to deploy a chute. Personally, I usually set it at 300' in a BT60 rocket, but on really windy days I'll set it at 200' with confidence and fly in conditions I wouldn't have risked losing a rocket before I bought my JLCR.

Thanks for the build thread - I'm enjoying this.
 
Thanks, and welcome. Unfortunately you got here just as activity is sort of taking a break, but I hope I can get *something* done soon.

I do have an Estes Crayon rocket that could make for a good test mule, although a 24mm rocket would be better with the extra weight. Good use of the C5 when it becomes available or I guess the QuestJets would work well for that as well.

Do you use yours with plastic chutes? I have nylons in a few of my rockets but more are plastic at this point. I could certainly purchase some more nylons if I have to.
 
I've used the chute release with both stock Estes plastic chutes and nylon ones. Mostly nylon, but both work just fine. Growing up I always packed the Estes chutes with the shroud lines wrapped around the outside of the chute like the directions taught me. That's not a good idea when using a chute release so I have to force myself to pack them "properly." I always pack nylon chutes "properly" but I just like packing Estes chutes the way I have always done it, so therefore I use nylon chutes more with the chute release.
 
BODY TUBE SPIRAL FILL AND MOTOR MOUNT... MOUNTING

I decided to try my current "CWF the whole thing" approach on the body tube. I am slathering it all over with my fingers, not going in any sort of spiral pattern, but just trying to make sure that the spirals look like they are CWF-covered when I'm done. I try to rub off as much excess as I can to minimize sanding. Here it is after applying the CWF:
bt cwf.jpg
And here it is after sanding:
bt cwf 2.jpg
Two observations:
  1. Even though it is a pretty large LPR tube, I found that both applying it *and* sanding it were still much easier and quicker than when trying to confine the CWF to the spirals.
  2. Secondary benefit is that any little surface imperfections in the tube get filled. The tube *feels* very good after this process.
The question is: how good of a job did it do filling the spirals? We'll have to wait and see; I won't be able to answer until I do a close inspection, and even then the true test comes when paint is applied.

I glued the motor mount in, and found (like almost always) that the large end of the tail cone didn't quite align perfectly with the body tube. This will need to be dealt with. Also, during handling I apparently dinged the surface of the tail cone a bit, so gave both the body/tail cone seam and the tail cone itself the CWF treatment. Here it is after everything is sanded.
tailcone-fill.jpg
That seam is far from perfect. I always have this problem with transitions and it is getting tiresome. I'll deal with it later, but don't assume I'll ever get it perfect.

Next up: filler/primer on the body.
 
I decided to try my current "CWF the whole thing" approach on the body tube. I am slathering it all over with my fingers, not going in any sort of spiral pattern, but just trying to make sure that the spirals look like they are CWF-covered when I'm done. I try to rub off as much excess as I can to minimize sanding.

I first tried this a rocket or two ago (is that a measure of time?) and I agree! It's faster, easier, and (I think) better results.
 
I would like to officially apologize for lack of progress on this build, which is essentially in stasis right now. I have had zero hours and zero minutes of bench time in the last... oh, however many years we've been stuck in side.

I'll get back to it eventually.
 
Yes, all the time I thought I would be saving by not commuting are consumed by all the other things. I'm mostly in a holding pattern as well.
 
I would like to officially apologize for lack of progress on this build, which is essentially in stasis right now. I have had zero hours and zero minutes of bench time in the last... oh, however many years we've been stuck in side.

I'll get back to it eventually.
Is that due to being too busy with more important things, or due to the isolation-induced funk (which you've mentioned earlier). I f the latter, I must truly urge you to push through that and start building. Depression and it's short term lesser cousin can sap one's enthusiasm for things that usually of interest, and yet doing those things anyway is one of the best ways to stave it off.

"Stay well" has become the new "see ya later", and it means mentally as well as virus-wise. And isolation sucks because it's necessary for one and detrimental for the other. So please do engage in hobbies.

Of course, if the reason id the former (above) then never mind.
 
I have two updates, here's the first.

After sanding the filler/primer, I took a look to see how well the CWF-everywhere worked:
spirals.jpg
The dark spiral lines indicate places where the filler/primer filled in spiral indentations. In other words, spirals not totally filled by the CWF. On the one hand, this indicates, that the CWF didn't totally do it's job. On the other hand, the whole point of the filler/primer step is to "finish the job". For me, I find that one good coat of filler/primer does *not* fill spirals, so if the CWF + filler/primer gives me a smooth body tube, then that is fine and dandy for me. The tube *feels* smooth; I cannot feel the spirals at all. So I'm going to say "looks good" for now, and the final word will be given by the paint (one day).

I also was not super-happy with the tail cone-to-body seam. Here's what it looks like after sanding the filler/primer:
Tail fuzz-1.jpg
The cardstock is very much roughed up there, not good. So I applied some thin CA with a cotton swab and sanded, and it was better. But not totally. So I did it again, and then again, and now it looks like this:
Photo Apr 26, 11 12 48 AM.jpg
Which is to say, you can't really tell if it's good from looking at it. It *feels* much better, and the surface of the CA is definitely much smoother than the rough cardstock was, so I think I'm in good shape. Once again, the paint will tell the tale.
 
You've proven yourself way better than I am at finishing, so take this for what it's worth.I'd be inclined to hit that seam again with filler primer before moving on. Just that band where the seam is, not the whole rocket.

And what about this:
1588000300362.png
It looks from here like that horizontal (in the picture, vertical on the rocket) area needs a bunch of work. Is that a photographic illusion, will it receive more filling, or do I just not know what I'm talking about?
 
You've proven yourself way better than I am at finishing, so take this for what it's worth.I'd be inclined to hit that seam again with filler primer before moving on. Just that band where the seam is, not the whole rocket.
Additional spray coats cost me dearly, so I'm willing to see how it goes the way it is. The extreme close-up definitely makes it look worse than it is.

It looks from here like that horizontal (in the picture, vertical on the rocket) area needs a bunch of work. Is that a photographic illusion, will it receive more filling, or do I just not know what I'm talking about?
That area will be covered by fin root and fillet, so it is left rough.
 
For me, I find that one good coat of filler/primer does *not* fill spirals, so if the CWF + filler/primer gives me a smooth body tube, then that is fine and dandy for me. The tube *feels* smooth; I cannot feel the spirals at all.

Yeah, and I think I see shades of CWF (new feature film?) in between the spirals, so that suggests that those parts of the tubes are flatter then they would have been without CWF (perhaps?). All-in all, I agree, I like the slather 1 coat of CWF -> sand -> prime method. But yeah, that looks good from here.
 
How much did you thin the wood filler so that it could spread over the whole tube?
I dunno, maybe a little thinner than dijon mustard? I'll probably go a little thinner next time, but don't want it to be too watery. The act of spreading it around with my fingers tends to dry it out rather quickly (or maybe the tube is absorbing the moisture, I dunno), so it needs to start a bit thin to provide some working time.
 
FIN SLOTS

In a normal build thread this wouldn't even warrant an entry, but when you don't have much to write about, you write a lot about a little. Let's cut some fin slots!

First I marked the locations. I printed myself a fin wrap and then realized that the markings on the tail cone are my reference. Using aluminum angle I extended the lines forward from the tailcone. I marked the locations for the front and the main fins. Then I sanded the front fin root area to clear it of primer, then re-drew the lines there.
front fin marks.jpg
Note the two vertical ticks on the right. One marks the back of the front fin, and one marks the front of the main fin.

Now it's cuttin' time. With the aluminum angle jammed against the tube, and running my snap-off blade against the aluminum, I cut my cleanest slots ever:
fin slot clean.jpg
And here's a quick dry fit of a fin.
fin dry fit.jpg
Pretty good. The slots are just a *bit* too wide, to the fin fit is a tad sloppy, but it'll glue up fine.

On my last slot I made a dumb error: I inadvertently cut to the wrong tick mark, that being the one that marks the back of the front fin.
fin slot error.jpg
I wish I could say it was because I was rushing, or some other excuse, but it was pure carelessness.

I knew immediately how I would fix it, and didn't even search the forum to see how others have done it. Now that I'm finished, I would nonetheless be interested to hear how others have closed up excess slottage.

I grabbed a piece of scrap balsa (leftover from the Solar Warrior fin sheet, from 2015), cut a piece to size, and glued it into the front of the slot like this:
fin slot repair 1.jpg
When the glue was dry I cut it down close to level:
fin slot repair 2.jpg
Then I sanded it flat, and realized I had over-sanded the tube a bit just below it. So I put a coating of TBII around the area:
fin slot repair 3.jpg
Then I sanded that smooth with 800 grit, applied some CWF (straight out of the tub), sanded once more, and finished:
fin slot finished.jpg
Looks good. In that last picture, you can also see that I sanded the primer from the fillet areas on either side of the fin slots. I have always (as far as I can remember, anyway) masked the fin roots before spraying primer. In hindsight I think that was dumb; it's *really* easy to sand the root area clean with some 400 wrapped around a dowel.

And so the airframe assembly is now finished.
 
I like your answer on slot filling. The only time I've faced anything a little similar is when I shifted the fins on my EZI-65 aft about 3/8", leaving a gap at the front of the slot. (This was to make the aft centering ring push right against the tail cone I was adding.) But on that kit, the tab isn't the full length of the root, so the overhang covers the gap quite well. Once fillets are done, there's no evidence.

That doesn't work in your case. Your answer is much better than what I would have done. I wound have "laminated" a piece of printer paper over the opening, just like papering a fin. Sand the edges a little and once it's painted it'll be close enough to invisible. I tine weak spot shouldn't matter.

Your way is way better.
 
All ready for filler/primer. Infuriatingly, I was blocked from spraying it today for dumb reasons. Now it'll probably have to wait for next weekend.
Readyforprimer.jpg
Actually, now that I have some time, I might move all that stuff to a thinner, lighter piece of wood. That one's a bit heavy to hold from the end. It was the first one I could find the approximately correct shape and length, but maybe I can find something better.
 
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