A nest of Yellow Jackets. Various sizes, various techniques (Launch Photos!)

[Marc_G]

Hi folks,

Some weeks ago, I finished up a SEMROC Trident build. It wasn't terribly difficult, but it drained much of the "rocket energy" out of me. My parts for an upscale version of it sit temporarily abandoned in boxes.

There's a surefire way to rekindle the rocketry fire in the belly. Build a YELLOW rocket. Or better, a yellow and black rocket. There's something about the color combination that stokes my fires.

But what to build? After due consideration, I decided my fleet needed an Estes Yellow Jacket, or close approximation thereof. I picked it because when I'm low on energy, the easy gratification that comes from polishing off a simple 3FNC type build is a very good thing.



New to cloning these models? Find the plan by searching for Yellow Jacket at the JimZ site!

So, I basically slapped one together in original scale (BT-50), did something about the woodgrain and spirals... at the moment, I forget precisely what I did, and then sat it on the bench in gray primer. I hadn't worked up the energy to actually paint anything, much less sand back the primer to get it ready to paint. In fact, to this moment I don't even have a single picture documenting the build. (What?! Heresy! No pictures means it didn't happen!)

More energy needed. So I decided what I really needed was a BT-60 upscale with a removable, interchangeable motor mount. So I built one (and actually have lots of pictures). And I got it into gray primer, and sat it on the bench. Not quite there yet, finishing wise.

No sooner had I finished the build than I remembered I had intended to also put a zipperless baffle in it. Drat. I put in the baffle but sealed it up, forgetting about the zipperless recovery part. But, that same day, while searching my launch field for a rocket lost long ago, I found a perfectly usable PNC-56 cone, from a long-decayed bird someone else had lost. The cone was dirty but perfectly serviceable, the remainder was mush. I usually leave remains undisturbed, like grave sites, in case anyone obsessive like me ever goes looking for their old birds, but based on age and remote location I decided to snag this one. Thus began my plans to build a BT-56 edition, with an Estes E 24 mm motor mount and a zipperless baffle. It's actually not in primer yet... but almost. I beveled the fin with my new beveling jig.

The last one, not started yet, will be a mini engine edition, based on BT-20 tubing. It will be cute.

So, is this a build thread or what?

Well, it's going to be more of a highlights reel. The forum has a lot of new members, and I thought some folks might like to see various techniques I used. Also, I figured it would be useful to document some the ways I'm doing things now. I evolve my techniques over time. Not always for the better, but I like to look back at early threads I did and see what the past looked like. So, this will serve as a public mile marker on my rocketry journey.

I'll also take some time to document my airbrush painting techniques. The Yellow Jacket is a pretty straightforward black and yellow bird, but what the hey...

Another aspect of this thread will be to guilt me into finishing the project. I haven't even ordered the decals from Excelsior yet. Maybe tomorrow. (Somewhere in Michigan, Gordy just felt a great disturbance in the force!)

So, stay tuned. I will gradually post highlights from the builds here. If you read the thread, I hope you find it interesting. Don't hesitate to participate. I welcome questions, comments, and constructive criticism.

But for now, the wife is giving me the "are you done yet?" look, so I'll wrap this up for tonight.

To be continued!

Marc

 

[K'Tesh]

I've got a clone of an original that's waiting to be finished... a BT-60 version that needs decals (applied, I've got them already)... and a Pro Series II 2" version in the works (and a 2.5" Cherokee D to go with it).

Looking forward to seeing what you're going to do w/yours.

Pointy Side Up!
Jim

 

[Marc_G]

Here is the trio of built birds so far:



Tonight I'll try to start documenting the highlights.

Marc

 

[Micromeister]

Here is the trio of built birds so far:

View attachment 170633

Tonight I'll try to start documenting the highlights.

Marc

It's such a nice flying model I had to downscale it for Micro Maxx Power. Great Flights regardless of size

 

[Marc_G]

OK, let's get highlighting. Starting with the fins.

For the BT50 and BT60 versions, I treated the fins mostly the same, except for the order of steps in the filling. I've only got pictures for the BT-60 version, using 3/16" balsa, so that's what you'll see. The BT50 version was done using 3/32" balsa, but looked mostly the same.

After cutting out the fins with a sharp hobby knife, and stack sanding them to make the edges smooth and even, I masked off the edges with light-tack masking tape to expose just the section I wanted to t bevel.



Above, I show the first side of each masked. I then masked the second side, making sure the masking on both sides was even. I then carefully stroked the fin back and forth across a piece of 150 grit sandpaper at about a 20 degree angle, periodically rounding over the end. After a bunch of strokes, the bevel reached back to the tape that serves as a marker as well as a protection from beveling too far back.

I did this for the leading and trailing edges, with some special effort to handle the two-part leading edge carefully. This is the result:



They came out pretty well, but I find it very difficult to do stuff like this by hand. Beveling the two sets of Yellow Jacket fins convinced me to come up with a beveling jig, which I've described over in this thread. You can see the BT-56 fins I did in that thread.

The fins were then coated with Elmer's Carpenters' Glue along the root edge and set aside to dry.

I'll discuss attaching them in the next post.

But right now, I've got to order those decals from Excelsior Rocketry.

 

[Marc_G]

OK, the decals are not only ordered, they've shipped.

At about 9:15 I sent Gordy at Excelsior an email listing the 5 sets of decals I needed. Four sets of Yellow Jackets in various sizes, plus an upscale Trident. When I woke up the next morning, I found a reply from him that he would get me a quote in the morning... the email had come through at 10:45. The dude burns the midnight oil!

I replied, indicating I had forgotten a decal set I needed (downscale Blue Bird Zero to replace one I lost). For any beginners unfamiliar with it, the Blue Bird Zero is a fun bird to build and fly.

Around lunchtime I already had my quote and PayPal invoice (very reasonable prices) which I promptly paid, and at 2:54 pm I had a shipping invoice... he had dropped them off that afternoon to the USPS.

If this sounds like a commercial for Excelsior, well, it is, albeit an unsolicited one. I've ordered from Gordy many times, always a pleasure. In addition to reproductions of commercial kits, he does great original artwork for my scratch builds. He is the waterslide king!

The usual disclaimers apply: I've no financial interest in Excelsior, just a happy customer.

 

[Marc_G]

I'm a bit under the weather today (had a migraine earlier, and taking care of my kids tonight wiped me out), so I'm just going to post a few comments about my decision process for how I handle making and finishing fins.

These days, if I'm working in balsa, I almost always harden the fins. I'm not worried about the fins breaking... that has happened to me relatively infrequently. I do worry about the fins getting chewed up by snap-back of the nose cone if the shock cord is to small/elastic, or getting dinged up on landing. Hardening the fins reduces the damage that tends to occur in routine flying.

But an even more significant benefit of hardening the fins is that they are easier to finish with a smooth paint job. The old school way of getting a good finish is to apply some sort of balsa sealer / filler, sand, repeat several times, and eventually you get a nice glossy finish. And some level of hardening the fins, though traditional butyrate dope isn't really that hard. Frankly, this is more work than I care to invest in the fins.

In my three models done so far, I've used three different approaches to the fins.

BT60: After attaching fins to body tube, I coated the fins in filler (Drydex spackle), sanded smooth, then soaked in thin CA (cyanoacrylate adhesive, or superglue). Sanded smooth. One or two coats of Rustoleum Automative filler primer, sand, and done.

The above is shown before the filler primer.

Original scale BT50: After attaching fins to body tube, I soaked them with thin CA first, then applied filler primer. Sanded smooth, one coat of spackle to fill small grain remaining, sand and done. Here are some pictures of various stages:

Filler primer sanded, spackle being applied:


BT56: Papered the fins using just a bit of light tack spray adhesive, then flood with CA, let cure, quick polish, single coat of filler primer, light sand and done.

My favorite way of doing this is the papering with CA. Click the link for an example. It is the fastest start to finish, and by far involves less work. The fins are the strongest of these variants, and have the best finish. The only downside is the toxic fumes and need for personal protective equipment (goggles, gloves, work in ventilated area).

Note my use of spackle/joint compound is somewhat capricious. I also use Carpenter's Wood Filler (not the MAX kind or the superior staining kind, both of which are gritty and too hard to sand, rather I like the regular kind). But spackle is a bit easier to sand, and in my application, works just as well as the wood filler.

Anyway, all three processes gave smooth fins that are hard and ready for painting. Here is the CA I use:


The final rocket, based on smaller BT20 tubing, will use basswood fins. Basswood requires much less work to get smooth finishes... a couple shots of filler primer, a fine sanding sponge, and you're done.

 

[Marc_G]

A few words about attaching fins:

1. I use double glue joints. I get the root edge of my fin coated in Elmer's Carpenter's Wood Glue, and let it dry. I put glue on the area of the body tube that it will mate to, and let that dry. Then I a light coat of fresh glue goes on the fin, and I stick it onto the body tube, hold it for 15 seconds, and it's on.

2. The problem is, I can never get the fin in just the right position by eye. Either it's crooked, or straight but sticking out from the body tube at the wrong angle, or some other offense.

3. While I realize I may have a deficit in manipulating parts by hand, I still don't see how people eyeball things when there are two fins that go on the same line, such as a main lower fin and an upper canard fin.

So, I built a fin gluing guide that I use for most of my builds. It has evolved over time, and I actually have two of them now. But if you want to know how I get fins on straight, even when there are multiple fins in a line, this is how:

https://www.rocketryforum.com/showthread.php?32360-My-quest-for-a-perfect-Fin-Gluing-Guide-(FGG)

Here's a pic of a different rocket getting fin treatment. Sorry, no pics of the yellow jackets getting their fins:


I used one of my two editions of this for the BT50 and BT60 versions.

For the BT56 version, I took a lower tech approach that works just as well, at least for simple fin arrangements. I'll document it tonight or over the weekend.

 

[Dean B]

I've been enjoying your Yellow Jacket thread, Marc. (Hope you're feeling better, btw.)

I share your affinity for yellow and black rockets - anything that resembles a poisonous stinging insect is OK by me. And you've seen enough of my rocket fleet to know that I like simple designs. (Skill Level 3- What's that???) But that's probably just evidence of my indolence in general.

I appreciate how you're showing different approaches of dealing with problems that arise during a build. I sometimes get in the rut of using the same methods over and over, so it's good for me to see how other modelers do things. I really like how you build and use jigs to increase the level of your craftsmanship.

Thanks again for sharing your build hints.

 

[Marc_G]

Woop Woop! Mail's In!

Looky what showed up:



Absolutely beautiful decal sheets. I need to consider how I'm going to finish the rockets, because if I'm going to use clear lacquer on them, I will usually put a thin misty coat of clear lacquer on the decals first. They handle a bit better if they are coated. They can also be coated with Future (Pledge with Future Shine or whatever they call that now...). Or used un-coated, though I tend to have more problems with decals that are uncoated.

Gordy took extra care to get these to me in time for the weekend, which is much appreciated.

Marc

 

[Marc_G]

Meanwhile, I mentioned that the BT56 version didn't use my fin jig, but rather used a lower tech approach.

Specifically, it used this:



Which is really just this, with some masking tape on it.



It is a sheet of paper/cardstock that has a piece of coupler material for BT55. So, a BT55 fits snuggly on it. With a wrap of tape, BT56 fits on it nicely. I used this to put the fins on the BT56 version by first marking where the fins go, then one at a time double gluing the fins, making sure they are straight with respect to the lines, and sticking straight out from the body tube by looking down from above. I didn't document this with pictures, so I decided to do it for the BT20 version with a full photo set for anyone unfamiliar with the technique.

First, I printed out the template. I used cardstock to make it a bit more durable than regular paper. I sadly don't remember where it came from, so I ask any readers here to let me know the source so I can give them proper attribution. I didn't make this myself! Thanks go out to whoever took the time to whip this up!

Be sure to print this out ACTUAL SIZE and not scaled to fit the paper.
View attachment 170967



Next, I assembled a cheap and easily available mandrel, some thick CA super glue (Works better than thin for this application), and a piece of wax paper to put under the area that will get super glue, to prevent it from soaking through and messing up the kitchen counter and incurring wifely wrath.



Voila!



Thick superglue takes a while to set up fully, so I set it aside to cure for a couple of hours. I could have used white glue or wood glue or anything else, but the superglue works well and doesn't induce wrinkles in the template paper that water based glues might.

The only trick is to make sure the mandrel is perfectly centered in with respect to the circles, or else all your fins will be off center when you glue them.

Once it is dry, I will show pics of using it.

For now, I have to cut out my BT20 fins.

 

[sandman]

OK, I'm watching!

 

[Marc_G]

Where were we?

Oh yeah. Fins. The three previous scales I've done used balsa hardened with CA. For the BT20 scale, I'm using some 1/16" basswood that I pre-filled with Rustoleum Automotive Filler Primer (from Walmart). Basically, you take a sheet of the wood (sourced at Hobby Lobby, in my case). Do a quick palm-sander pass with 220 grit paper (takes maybe a minute or two per side) to make sure you are starting with a smooth piece of wood. Lay it on a piece of newspaper outside. Spray on a heavyish coat of primer. Let dry for half an hour, then flip and repeat on the other side. Repeat once again for each side. Let dry... I usually let it dry a few days, but if you are in a hurry, you can sand it after a few hours. Sand with the palm sander on each side, and give it another coat on each side. Palm sander again, maybe 320 grit this time, AFTER IT IS FULLY DRY. The sheet is now ready for use.

Here is the sheet I'm currently using, which I pre-primed maybe a year ago:



You'll see this one is a bit warped. It wasn't the greatest sheet to start off with, and I didn't store it correctly... but for cutting out small fins there's no problem. Total warp over the span of a fin is minor.

To create the scale fin pattern, I use the PDF of the actual scale fins, and print it out using Autodesk Design Review. It includes a print function that allows printing at any scale, which is missing from the Adobe Reader version on my computer:



For a BT20 downscale from BT50 original, we're printing at 75%.

I print onto cardstock and cut out a fin:



Then use this template to cut out three fins from my pre-finished material, being careful to orient the grain of the wood with the leading edge of the fin.



Above are the raw fins, I stack sanded them to get the edges nice and clean.

I then used my beveler to put bevels on most of the edges (except the root edge!).



I was a bit nervous about uniformity of beveling on such thin stock (thin is harder to do than thick! because any small variance is a big % of the total bevel). They came out better than I could have done by hand, and the process took maybe 5 minutes total. There are a few places I might need to touch up later.

 

[Marc_G]

Next, I sanded off some of the primer along the surface of the fin adjacent to the root edge. No need to get picky about getting it all off, I was just going for about two millimeters of mostly-removed-primer following the root. This would allow better penetration of the wood glue into the wood for the fillets. Note, primer is porous, so this step isn't critical. But I think it's a worthwhile practice. Sorry, no pictures.

The root edge and adjacent surface got a thin coating of the Elmer's Carpenter's wood glue, and were set aside to dry.

Meanwhile, I put markings on the body tube. Note: I used an existing length of body tube that was a bit more than 8.5" long; to be proper scale, I should have cut a fresh piece to a bit more than 9.5". So, my model will be shorter than scale by about an inch. Sue me

Here are some pictures that show the use of the Tube Marking Guide and some channel aluminum to put parallel marks on the tubes:





There's no great insight there... I just marked the three points with tick marks, rotated the tube a bit, marked three new spots, extended the lines with the channel aluminum (which works great on small diameter tubes), and eventually put some glue on each of the three areas of attachment. I did lightly sand the glassine in the area where the glue went. This is NOT required. Glue will soak into glassine. But I think it does make for slightly better attachment.

This was allowed to dry before proceeding.

 

[Marc_G]

To stick the fins on, I put some glue in a line on a piece of wax paper, dipped the root edge of the fin in it, and got rid of excess by tapping the root onto a dry area of the wax paper:



I then carefully stuck the fin onto the tube, holding it tight, making sure to align it straight relative to the marked lines, and centered between them... note the centerline of the fin guide line is right between the two marks in the above pictures, so I did the best I could to stick the fin on right centered between the lines.

For the first twenty seconds, I hold the fin on focused just on keeping it up against the body tube to activate the glue. It grabs quickly. After that, I then sighted down the tube and made sure the fin was sticking straight out from the tube aligned with the fin line:


I might hold the fin there for a minute or so to make sure the glue starts to settle with the fin in the right orientation. After that, you can let go.

One done!


After just a few minutes the job is done. Here's a pic showing the glue I use. It is a shrink yellow glue which does a fabulous job for this task. Shrinky glues hold the fins tight and tend to be less bendy at the joint than non-shrinky glues like Titebond II. Nothing is wrong with Titebond II, and lots of folks use it, I just prefer the feel of the Elmer's Carpenter's yellow glue for this task.



Perfect alignment. Any deviation is purely due to camera perspective. :wink:



I did make a notable goof. I forgot that the body tube didn't go quite all the way down to the paper fin guide template, but was suspended just a bit off. I forgot to put the fins on slightly elevated too, so they extend below the body tube just a bit:



I eventually sanded the stubs down after the pics in this post, and nobody but me would ever notice the error, but I document it here so you won't make the same mistake.

Later, after the initial glue was fully dry, I gave a thin fillet of the same yellow glue.



This looks like more glue than it is. It was smoothed with a damp pinky finger. So that it wouldn't run, I let it dry in horizontal position, without putting any weight on the fins that might bend them out of alignment. In the morning, I gave a thin fillet of Titebond Molding and Trim Glue (No Run, No Drip formula).

 

[Marc_G]

Making the mini engine mount was no big deal. I'll document it quickly.

I had some BT5 tubing to start with. I marked an appropriate length and put some spent engines inside, for support:



I used the above-shown tube cutter to slice cleanly through the tubing. With the engines inside the tube, the razor makes a nice clean cut in a few passes.


I then gradually assembled the motor mount with an inner engine block, an engine clip, and a couple centering rings. The bottom ring has a section cut out, to allow free motion of the engine clip.

Note, I like to use non-shrink glues, such as Titebond II, for anything involving centering rings because it doesn't cause "wasp waist" or "coke bottle effect" like the regular carpenter's glue would. Even though I'm making yellow jackets, I don't want wasp-waists.

 

[Marc_G]

I tied some 75 pound Kevlar cord to the assembled/dried motor mount, and used a file to make a notch in the top centering ring. I taped the Kevlar down, and also covered some of the Kevlar in tape as a blast shield to make it last a bit longer in use.



Squirted a few drops of Titebond II into the hole, and shoved 'er in:



The shoving in part was done quickly to avoid the glue grabbing before positioning was done. Some folks prefer to use epoxy because it is immune from this problem. As long as I work quickly, I haven't had a problem with Titebond II.

We'll now switch gears a bit. I'm going to let this rocket dry (glue inside dries slowly, takes a day or so) and make sure it's launch lug is well-shaped. Meanwhile, I'll document the motor mount on the BT60 version.

 

[Marc_G]

For those of us that like clustering engines, BT60 birds can represent a challenge.

Without clustering, if you think you want to use various sized engines, you can easily just build the rocket with a mount sized for the largest engine you will use, and use an adaptor to adapt down to smaller engines. Easy.

But when you have a BT60 rocket, and might use single 18 mm, single 24 mm, or triple 18 mm clusters, you can't build a one-size fits all single mount.

To get around this, I designed an interchangeable motor mount with twist-lock action. Thanks go out to many others that have posted their own interchangeable designs that helped inform my own implementation. Rather than talk through a step by step design I'm going to post a bunch of pictures first:

 

[Marc_G]

Acting as a forward thrust ring is a centering ring (BT55-BT60 I think) that I glued into the body tube:

I pushed it in from the top, and pushed it farther aft than it would eventually be:



Then I inserted one of the motor mounts and pushed the ring forward almost into position, stopping a few millimeters shy.



I then used a qtip on a stick, and put glue all around the edge.



I then finished pushing the motor mount fully into position, fully seating the centering ring into the glue. I then removed the motor mount just in case it was touching the glue.

Here it is, after drying:



I've got four mounts that fit: 18 mm, 20 mm (for now out of production Quest D5 engines), 24 mm, and 3x18mm.

All of them share a common distance from forward centering ring to back of the rear one. The triple mount uses little strips of basswood, sanded to fit, in place of the rear ring. But the back side of those wood strips lines up with where the centering ring should be, if there were one.

Any of these can be inserted and twisted to make sure the ejection charge won't kick it out, based on the rectangular basswood strips in one of the above pictures that are glued into the rear part of the BT60 tube. Note that I glued them in close to the fin attachment points, for greatest strength.

Marc

 

[Marc_G]

This evening was "white primer night" for the BT50 and BT60 models.

When airbrushing rockets, I use a four-step system:

1. Auto filler primer, sanded down. Rockets look like this at this stage:



2. Auto-Air Sealer White or Sealer Dark. In models that are two-tone, like the Yellow Jacket, my routine is to do the whole model in the Sealer White rather than use "Sealer Dark" (basically, black) on the areas that will be dark. In compensation, I hit the dark areas with a second layer of dark color coat at the appropriate time.

3. An opaque white paint, any of the Wicked / Auto Air / Autoborne line. This is VERY important if you are going to be doing a lighter color like yellow as the color coat. Even with the sealer white on the bird, the rocket isn't really white yet. Splotches of gray will show through when you color coat... it's like the thinner areas of the sealer coat become a bit translucent, letting the gray primer show through. Putting a solid opaque white color down really makes yellows / oranges pop!

4. The actual color coat. Airbrush paints are intended to go on in several thin layers, so it can take time to get to the color you want. Patience is key.

So, let's talk tools of the trade.

I've got a CO2 cylinder for pressure. I like it because it makes no noise. Most of my painting is done in times when others in my family are napping and or sleeping, so silence is bliss. Costs me about $75 / year for gas. I'm good with it. Most folks go with a compressor, which is more common.

For brushes, I've got three types:



My first brush was a Paasche H brush, shown in red. Good single action external mix brush, bought for ~$60 with coupon at Hobby Lobby, as part of a set with some bottles and tips and stuff. Used it a lot but it eventually drove me crazy. Probably, whatever airbrush you get first WILL drive you crazy. I found that while it works fine, I often want to cover more area, or less... so the middle of the road brush with relatively few adjustments wasn't the complete solution.

I got a ~$20 internal mix brush (blue) from Harbor freight. Actually closer to $30 when you factor in the cost of the air hose you need for it. But it atomizes the crap out of the paints I use, and covers pretty quickly, which I like, gives a good even coat. Love this thing. Hardly ever use the Paasche anymore. In fact, I bought a second one at some point. IT is a bit of effort to clean, so I use the Paasche (which cleans up quicker) for quick jobs where I'm swapping colors a lot. Otherwise, I use this one. It is a bit finicky because it is not much of a precision instrument, but when you get the hang of it you can dial it down to an eighth of an inch or wide enough to cover BT56 pretty quickly at good flow.

The best thing I ever did was invest ~$10 at Harbor Freight for the small spray gun shown in purple. I think it has a 4 ounce cup. It's a cheap thing but I use it more than any other airbrush. For any rocket more than BT50 sized, the smaller airbrushes can be a pain to get coverage in a reasonable amount of time. This mini spraygun really goes fast, and you get a relatively thick coat fast. You have to be careful to avoid runs, but with a little practice it's easy. You do waste more paint with this puppy, but for speed and uniformity of coating, it can't be beat.

So, I put about half an ounce of Sealer White in it (NO THINNING/REDUCING of the paint):



And blasted the BT50 bird. It took maybe 2 minutes to get a good even coat:



Then I hit the BT60 one which took longer and I had to refill the cup a bit, but it came out even too:



Then I set them aside to dry while I spent 10 minutes cleaning the gun:



Couple things to remember:
A. Heat causes the paint to polymerize. Don't use hot water. Just slightly warm water, and lots of it. The airbrush cleaner Createx sells works fine too, as long as you rinse a lot with water afterward.
B. There are two states of an airbrush: clean, and not clean enough. I have made the mistake of not sufficiently cleaning a brush, and spent a LONG time soaking parts in solvents and carefully cleaning the dried crud out. Spend the time while the paint is wet to do the job right.
C. Use a compressed air cleaner (I got a six-pack at Costco for cheap, in the office section) to blow out the parts. Often you'll see little bits of color come out. Keep cleaning!

Here's a view though the finally-clean nozzle of the spray gun.


One more tip: you can get Wicked Colors at Hobby Lobby. Cheap with coupon. But they usually have some colors in the clearance aisle for a buck or two each. I've accumulated quite a few colors as they have rotated stock. About half of what you see here has been obtained for a steep discount:



Art stores usually have quite a bit of selection too. TCPGlobal has an amazing array as well, of the AutoAir/Wicked colors. They have metallic, pearls, all sorts of special things.

I haven't much used the plain Createx acrylics outside the AutoAir/Wicked lines, and I think they might be a bit harder to spray without thinning. I'll invite others to comment on that. I stick with what works for the most part.

In a day or two I'll get around to putting the white coat on. I won't bother much with pictures since it will look much like what you see now!

PS: I recommend the use of a particle mask or respirator. Just because these aren't stinky like lacquer/enamel paints doesn't mean they don't have nasties in them. You don't want to breathe the rainbow, so to speak!

Marc

 

[Marc_G]

At the start of this thread I mentioned I'd demonstrate a zipperless baffle.

I incorporated one into the BT56 version of the Yellow Jacket. I had actually intended to do it for the BT60, but I goofed. More on that later.

The baffles I use tend to be simple couplers with three half-moon panels in them. The panels are at the top, middle, and bottom of the couper, and positioned inside the coupler so that their is no direct path through it... the hot gasses have to shift direction. And hot particles can't just shoot straight through.

There are more elegant designs of baffles, but these work for me.

This shot pretty much says it all:



I use 1/32nd plywood I got from Hobby Lobby or Micheal's for the job. I rub it with wood glue to give the wood surfaces something of a protective coating.

Since I'm using this for zipperless construction, I doubled up on the top baffle plate by using a pair of half moons glued together. A small screw eye goes through, with a washer to spread out the force of shock cord pull.

It seats into the bottom section of a rocket, such as this one:



When dry, you get this:



The screw eye I used was sourced from Lowes, but as you build bigger birds you are better served by some place that sells better forged screw eyes. At the small end, I haven't found a local supplier, though I haven't looked much.

I also treat the exposed part of the coupler with thin CA, then sand I down smooth. This helps ensure the forward end of the rocket will separate properly at ejection. I'll show more pictures later, with shock cord and such when I'm closer to done with it.

I mentioned I goofed with the BT60 bird. I had planned to do exactly this with the coupler for the forward / rear sections of body tube. But I had a brain fart and instead went ahead and glued in the coupler to the forward section:



Oops. When I realized what I had done, I decided to turn lemons into lemonade. I made a BT50 stuffer tube, and put a baffle inside that. With some centering rings I was able to properly and cleanly attach things:



Not shown is a shock cord attachment point in the upper part of the BT60, secured to the upper end of the stuffer tube assembly. The pic shows the cord coming out the top, not how it's mounted. Basically, knotted around the BT50 tube, fed through a notch in the centering ring. But bottom line, I've got a baffle, and through the use of a stuffer tube in this larger rocket, I've increased the likelihood of deployment if I use just a single 18 mm engine, through reduction of the volume of tube to be pressurized.

Marc

 

[Marc_G]

Tonight I sprayed on the opaque white, sort of.

Here's a trick I do. I find it very hard to gauge coverage of opaque white topcoat over white sealer primer. So, I mix just a bit of the eventual color (yellow, in this case), into some white. That gives me the opaque coverage of the white, with a bit of yellow tint, allowing me to easily gauge coverage as I spray.



In the above pic you can see a small plastic jar I got at Hobby Lobby (a pack of various sizes for $4.99, about 15 or 20 total!). I put about half an ounce of opaque white in it, and squirted a squirt of yellow in. Capped it, and mixed back and forth for a minute.

Then I put it into my mini spraygun and blasted a thick (but not runny) coat onto both birds. I covered the BT50 most of the way up, leaving some uncovered (it will get black coat there, don't need to cover with opaque white or eventually yellow). I covered the entire BT60 rocket, because there was plenty of mixed tinted paint left over.

I tried to capture pics showing the color differential, but only one really shows it, in the contrast between the white top of the BT50 bird and the totally yellow-tinted BT60 rocket.



Still sort of hard to see in the picture. Easily visible to the naked eye.

I took some other pictures of the sealer-coated rockets as documentation of smoothness... they didn't come out great. I'm not a macro wiz. Bottom line: some spirals did show through, in some places. Bummer. Otherwise pretty smooth.

 

[Marc_G]

I taped the body tubes using 3M masking tape (light tack/delicate surface) at just over 8" from the rear on the BT50, and the corresponding location on the BT60. I've found that old kit bags make excellent masking material:

 

[Marc_G]

It only took a few minutes with the mini spraybrush to put on a coat of Auto Air Iridescent Brite Yellow. I coated each rocket, moved to the next, then gave each of them a second coat FROM A MORE DISTANT SPRAY POINT. I've found this makes the iridescent / metallic flakes lay on more evenly at the surface and improve the uniformity of the look.



Note, if this was plain yellow I might not have bothered to mask. However, since the iridescent yellow dries slightly rougher due to the included flakes, I didn't want to have that rough surface under where the black will be, particularly not in an irregular fashion.

 

[Marc_G]

Meanwhile I've been getting the great decals from Sandman ready.

I taped them into a box I use for stuff like this. Note, you may see some sawdust in there, but I use this box for spraying glue, too, so those bits of crud are glued down tight. No worries of them contaminating my surface.



I sprayed a light, misty coat from pretty high up. The result is a pebbly surface. You DON'T want an even glossy coat at this point. The coating with just a bit of clear, irregularly, makes the decals more resistant to damage in handling and they go on more evenly. Time to get a glossy smooth coat is later, after they are applied.



I set them aside to dry.

 

[Marc_G]

So, I nearly botch the job. But it's back on track. Here's the story.

First, I pulled off the masking from the iridescent-yellow-painted rockets:



I got remarkably sharp lines, even though the interface will be covered by black paint.

Then, I taped just a bit lower. This is where I sort of screwed up, part A. I forgot to use Tamiya tape that would be more reproducible in giving a good line when I overcoat with black.



Part B: I also forgot to use some acrylic transparent base around the tape to seal the edge. I use transparent base because a thin coat will soak into any breaks in the tape edge and prevent bleed through of the topcoating color, and being transparent, you won't see it.

Here they are all ready for spraying:



Next comes screw up part C. I thought I had a bottle of black Auto-Air paint. Oops. None such. I did have several smaller bottles of wicked black colors. I decided to use Wicked Pearl Black. This is where the screw up comes. Pearl black (at least my bottle of it) is extremely thick. Even though I noticed this when I squirted it into the spraybrush cup, I just moved forward without doing anything about it. My brain must have been offline or something. When I started spraying it just sputtered pitifully then stopped. This was the result:



Only a tiny bit of paint came out and I could literally see my fingerprints on the white tube from handling it. It was like dusting for prints.

I mixed some more paint with a bit of Wicked reducer, and gradually got it fed into the spraybrush, mixing with the paint already in it . I was able to get the rockets coated nicely. Here is a pic after the first coat; I later put on a thin second coat:



After drying overnight, I removed the masking and observed the fruit of my labors:

 

[Marc_G]

Next up, decals.

I cut all the decals out of the sheet, and got some warm water ready, and had a small vial of Future (Pledge with Future Shine), and some brushes and such ready.



I had lots of trouble with the wraps. I must be out of practice. Fortunately these are high quality tough decals from Excelsior, and they stood up to handling. After botching the first attempt to roll the BT50 wrap onto the tube (which I had painted with a bit of Future as a setting solution), I had a wrinkled mess. I carefully unpeeled the wrap and floated it into the water:



I then carefully pulled it up back onto its backing sheet. I then took a second stab at rolling it into place. This time I did a better job, though not perfect. I called it quits despite a mismatch over near the launch lug where the ends of the wrap met. I always make wraps meet up near the lug because usually that is not the "photo opportunity" side.



The other side looked good:



More decals finished it off. No problem with the rest:

 

[Marc_G]

The BT60 version gave me similar challenges with the wrap, but perseverance paid off:

 

[TopRamen]

That looks Awesome! Nice Work.:clap:

 

[ereinert]

Awesome! Looks really good. I agree, Black and yellow are definitely complementary colors.