Leviathan Build (for L1 cert flight)

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lcorinth

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I started building the Estes Leviathan, along with two other PSII kits, nearly a year ago. Eventually, I decided one of them would be my L1 cert flight vehicle. This one got finished first, so it'll probably be the one. It turned out nice, so I thought I'd post the build here.

Before we begin, I'm sure someone will tell me I overbuilt this thing, and it's true. But I had a year's less experience when I started, and I wanted to try some of the stronger HPR building techniques on something cheaper, and from what I understand, it's pretty common for HPR beginners to be a little overcautious with the building. So, the rocket's a little heavier than it could be, but it will be less likely to lose a fin.

I started with the fins.

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I usually shape balsa fins on LPR models, so I wanted to see if it was doable with a plywood fin, since all I have is a hand sander. Since I wasn't sure how easy it would be, I swiped one fin from my Estes Scion (which is the same rocket, but with a longer body. The Scion has three fins, but since it's just repackaged Leviathan parts, it comes with four). I figured if it worked, I'd use the rest of the Scion fins for this rocket, and if it turned out terribly, then I'd just leave the fins on the Leviathan square, and I'd still have three fins for the Scion.

Whether it'll make this rocket fly better or not was kind of irrelevant to me, as I knew I'd be building heavy. I just like the look of airfoiled fins, so I figured I'd give it a go.

I mark where I want the tapers to be using a... actually, I forget what this thing is called, but it's a cheap tool for measuring hemlines on pant legs and such.

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I'd have a slight taper on the leading edge with the actual edge rounded over, and a slightly longer taper on the trailing edge.

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Connecting the marks...

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I start sanding at about a 45 degree angle on the leading edge, down to the darker middle ply. This gives me a corner I can sand off, slowly working my way down to the line where I want the taper to start.

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It's been a couple days since I started this thread, but I wanted to edit video before continuing.

I sanded all fins into airfoil shapes. Though I do have pictures, I also have video. I sand most of my LPR and MPR balsa fins into airfoils, but wasn't sure if I could do it with plywood with only a sanding block.

I gave it a go, and it turned out great. Just as easy as balsa, but you need a coarser grit of sand paper and a little more patience.

[video]https://youtu.be/AI2jtedVBwI[/video]

Edit: How do you guys upload YouTube videos that will play on the forum? Every time I do it, it just shows up as a link to YouTube.
 
It's been a couple days since I started this thread, but I wanted to edit video before continuing.

I sanded all fins into airfoil shapes. Though I do have pictures, I also have video. I sand most of my LPR and MPR balsa fins into airfoils, but wasn't sure if I could do it with plywood with only a sanding block.

I gave it a go, and it turned out great. Just as easy as balsa, but you need a coarser grit of sand paper and a little more patience.

[video]https://youtu.be/AI2jtedVBwI[/video]

Edit: How do you guys upload YouTube videos that will play on the forum? Every time I do it, it just shows up as a link to YouTube.

I think it only puts the link I'm not sure. I can view it on my phone just fine.

Is that a tungsten carbide sanding block? I swear I need to get me one to do neat airfoils.

Great video on the airfoil tip, thank you for sharing.


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
I think it only puts the link I'm not sure. I can view it on my phone just fine.

Is that a tungsten carbide sanding block? I swear I need to get me one to do neat airfoils.

Great video on the airfoil tip, thank you for sharing.


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

It's aluminum, from Great Planes. It's available online. I got mine from Amazon for around 8 bucks. It's by far my favorite tool in the box - in fact, I have two of them!
 
When you want to add a video to your post... look at the bar that allows you to add a link, break a link (Unlink), Insert Image, Insert Video, (looks like a couple of frames of film), and adding a quote ( wrap "[" QUOTE] tags around selected text). Click on the "Insert video", paste in your link, and click on "OK", and it should be visible when you save your post.

Then again, I'm currently in China, so YouTube is spotty when the internet connection (or VPN) isn't 100%.

[video=youtube;AI2jtedVBwI]https://www.youtube.com/watch?v=AI2jtedVBwI&feature=youtu.be[/video]
 
It's aluminum, from Great Planes. It's available online. I got mine from Amazon for around 8 bucks. It's by far my favorite tool in the box - in fact, I have two of them!

$8 damn, thats sure is a heck of a deal. Would be a good alternative than the tungsten carbide blocks that are at $25, plus shipping it goes up to $30. Will see about getting one later on.


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
Looks great Daniel - mine is a little tank too. I'm sure your using a CR because a Leviathan on and H is going to scoot! I friend of mine certed L1 with a Lev and had about 3/4 mile walk...pre chute release that is. Going to be cool! hope to fly mine on an H as well
 
Looks great Daniel - mine is a little tank too. I'm sure your using a CR because a Leviathan on and H is going to scoot! I friend of mine certed L1 with a Lev and had about 3/4 mile walk...pre chute release that is. Going to be cool! hope to fly mine on an H as well

Definitely using a Chute Release. Probably going to set it to 400 feet.
 
Once I got all four Scion fins airfoiled to my satisfaction, I started on the motor mount.

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Like on my Nike Smoke build, I labeled the forward and aft ends of the Leviathan motor tube, to avoid any confusion. I also labeled which rocket it went to, since I started building three PSII kits at one time. This is less to avoid mistakes (since all the motor mounts look different), as much as to figure out which pictures go with which rocket when I got around to posting these online.

The green paper "spacer ring" helps you get the centering rings on perfectly straight.

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I started with the aft centering ring. Slide the spacer on, then slide the centering ring down over top of that. This will not only ensure that you get the ring on straight, it will also leave enough space on the aft side of the ring to install the screw-on "Quick Release" motor retainer.

Rather than glue the ring on with a fillet, I simply tacked it in place with a couple drops of thick CA. I would be removing this ring before installing the fins.

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Once the aft CR was tacked into place, I slid the middle CR onto the motor tube followed by the green spacer ring. I had marked where the centering ring should go, but in order to get a precise placement, I used the fins to make sure there was just enough space between the aft and middle centering rings, as per kit instructions.

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Once I found that spot, with the spacing ring keeping the middle centering ring in place, I tacked the CR down with thick CA.

Before I continue with the MMT build, I'm going to back up a little...
 
Before we begin, I'm sure someone will tell me I overbuilt this thing, and it's true. But I had a year's less experience when I started, and I wanted to try some of the stronger HPR building techniques on something cheaper, and from what I understand, it's pretty common for HPR beginners to be a little overcautious with the building. So, the rocket's a little heavier than it could be, but it will be less likely to lose a fin.

So far, I haven't seen much "overbuilding". When you feel the urge to go overboard on this, resist. The Leviathan will work just fine without over building. I built mine stock and actually followed the directions pretty close. I've flown it on H128W and H180W and it's held up just fine. The H180 is probably as big as I would go in a the stock Leviathan, but it will handle the H128 baby H just fine.

Have fun with your cert!
 
So far, I haven't seen much "overbuilding". When you feel the urge to go overboard on this, resist. The Leviathan will work just fine without over building. I built mine stock and actually followed the directions pretty close. I've flown it on H128W and H180W and it's held up just fine. The H180 is probably as big as I would go in a the stock Leviathan, but it will handle the H128 baby H just fine.

Have fun with your cert!

The rocket is already built. You'll see what I mean by overbuilding later in the thread (I'm posting a few pics at a time in my spare time). Nothing major - just a lot of epoxy for internal fillets. And a lot of people do that - but someone is bound to point out my overuse of epoxy, so I thought I'd put the disclaimer up front.
 
It's aluminum, from Great Planes. It's available online. I got mine from Amazon for around 8 bucks. It's by far my favorite tool in the box - in fact, I have two of them!

I have one too, actually two. And instead of buying two, get the longest one, and cut it into two pieces, one about 8" and to the other is about 18" long. They're also great at making axial lines on body tubes, and used as a cutting guide for fin slots..
 
When you want to add a video to your post... look at the bar that allows you to add a link, break a link (Unlink), Insert Image, Insert Video, (looks like a couple of frames of film), and adding a quote ( wrap "[" QUOTE] tags around selected text). Click on the "Insert video", paste in your link, and click on "OK", and it should be visible when you save your post.

Then again, I'm currently in China, so YouTube is spotty when the internet connection (or VPN) isn't 100%.

[video=youtube;AI2jtedVBwI]https://www.youtube.com/watch?v=AI2jtedVBwI&feature=youtu.be[/video]

OK, I figured out what went wrong. If I click on "Share" on YouTube and paste that URL into here, it just shows as a link. But if I copy the long URL from my browser, it shows up as a playable video on TRF.

Thanks for the tip.
 
UPDATE: Will post more photos tomorrow, plus start a new thread of my Ventris build (I started Leviathan, Nike Smoke, and Ventris all at around the same time). Today was long and I'm tired.
 
Before I continue with the MMT build, I'm going to back up a little...

I didn't think it would take me as long as it did to finish this rocket. And I didn't think I'd use it for my L1 cert. While I was aiming to get started in HPR, I thought I'd get something different, maybe with a 38mm motor mount, because I had heard that's a good size with a wide motor selection. So, when I started on the Leviathan, I was thinking that a) it would just be a mid power rocket for me, and b) I'd be done quickly. I wanted to start looking for motors I could use in it, so I started playing around with sims.

There is a sim of the Leviathan over on Rocket Reviews, and while it's pretty close, the fins at least are a little bit off.

RR Leviathan.jpg

Thankfully, K'Tesh has this awesome thread where he posts his OR sims. I downloaded his Leviathan sim.

K'Tesh Leviathan.jpg

In order to get an accurate flight simulation, you need to remove all the extras. To get the rocket to look right in the 3D view, K'Tesh will add things like phantom body tubes or phantom fins for bands of color. Most real nose cones are not truly pointy, as they appear in OR, so K'Tesh will make a tiny little round nose cone with a large transition, so the "nose cone" in the sim is in fact two pieces, but it ends up looking much more like the actual nose cone from the kit. So I got rid of all the extra stuff, changed the nose cone to a singe ogive piece, and then I weighed every single part of the rocket, overriding all the mass values.
 
I mentioned the RockSim file from Rocket Reviews. Here, compared with the K'Tesh sim, you can see the difference in CP.

K'Tesh Vs RR Leviathan.jpg

However, the K'Tesh file, in order to simulate different colors, has "phantom fins." Despite the fact that these are merely there to represent skins of paint, they do seem to affect the Barrowman CP calculation. When you remove them for a sim flight, you can see that the difference in CP between the two simulations is only a few millimeters, so either sim will probably work fine.

K'Tesh Basic Vs RR Leviathan.jpg

Still, I stick with the K'Tesh file, because it's got more accurate fins.

Now, I weigh all my components and override the masses of everything in the sim.

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No need to upload every picture - you probably know what weighing things looks like. Here's the sim after inputting all the overrides.

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OK, so now I have an accurate CP calculation, and probably an accurate CG calculation. But, of course, the CG (and overall mass) doesn't include things like glue or paint.

Still, I decide to sim some motors. First, I look at the G40 I have.

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1.04 caliber stability with the G40. Again, without glue or paint. By now, I have the H133 I'll use for the cert flight. Let's see what that does.

Leviathan Basic Sim CG H133.jpg

Even without glue, it looks like the H motor will make this rocket marginal.

But there's an element I'll add even before considering glue. I've decided to attach the shock cord to the forward CR with an eye bolt.

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And the result...

Leviathan Basic CG Eye Bolt.jpg

With the G40...

Leviathan Basic CG Eye Bolt G40.jpg

Now the rocket sims as marginal - even before accounting for glue or paint. With the H133, it will be even more marginal.

I was pretty surprised by this, and had several thoughts:

1) Maybe I ended up with a denser-than-normal fin set,

2) Maybe OR's CG calculations were off, or...

3) Maybe the Leviathan is one of those rockets which fly fine even when marginal (though that's not a risk I'd be willing to take as an HPR beginner).

Much later, closer to finishing the rocket, I asked about this on the NAR Facebook page. Everybody seemed to think I was doing something wrong. Nobody reported a marginal Leviathan. I'd been pretty careful with my measurements and overrides. Nonetheless, at this stage, I know to make note of it, and check the CG and CP once the rocket is built. If need be, I'd add nose weight.

OK, now that the sim background is out of the way, next post will be back to the actual build.
 
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I know you mention you haven't factored in glue yet but some fillets on the back can have some serious mass on a light rocket. I built a Leviathan awhile back as well and on an F26 the thing flew like a beaut. I think that some designs are prone to fly more stable than others even if they have a small stability margin. Keep us posted, I would be curious to know where the actual CG lands on the rocket once your done.
 
If you've been reading my Nike Smoke build thread, you know that I installed the motor mount as is according to the kit instructions. But, as I started to think about the Leviathan, I thought I'd like to try some of the HPR build techniques I'd been reading about online. And one of those techniques was mounting the shock chord to the forward centering ring, and using something sturdier than the elastic band that came with the kit.

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I marked the forward CR at a spot close to the middle, clamped it down, and drilled a hole.

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I applied some JB Weld to the hole and inserted the eye bolt.

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While waiting for the epoxy to cure, I cut the aft centering ring off the motor mount. It had originally gone on so that I could accurately space the distance between it and the middle centering ring. Now it needed to come off.

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Using the green spacer ring, I found the spot where the forward centering ring needed to go. I flipped the motor mount over on the edge of the table, and put wood glue fillets on the aft sides of the middle and forward centering rings, securing them in place. The eye bolt hung over the edge of the table.

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The aft-side glue fillets on the middle and forward centering rings are dry.

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I flip the MMT over and apply epoxy fillets on the forward sides of the centering rings. I also attach the spacer ring to the forward end of the motor tube.

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I've decided by this point to skip the elastic shock cord and try something I'd read about. I got some nylon strap.

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I cut a nice long piece. I forget how long, exactly, but it's at least 3-4 times the length of the rocket (plus a little bit, the part that's inside the airframe). I weigh the shock cord and plug the mass into OpenRocket.

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Now it's time for fin filling.

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I'm told I could go with just some filler primer on these, but my results doing that with other fins have not been to my liking. I figure it could take me a lot more coats to hide the wood grain. So I go with what I know from LPR builds - Elmer's Carpenter's Wood Filler, sometimes called Fill n' Finish.

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After sanding the CWF, they're pretty smooth.

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Finally, I drill three holes near the bottom of each fin tab.

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Then I let several months go by...
 
Here, I missed a few photos, but the gist is that I tied on the nylon shock cord, pulled it through the back of the motor mount, and installed the motor mount, using Bob Smith 30 minute epoxy. Then I got a Nomex shock chord sleeve from Sunward and put that on the shock chord.

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I install the tube coupler, skipping the epoxy this time and just using wood glue. It was quicker and less messy. Then I drilled holes for the rail buttons. I drilled one hole just forward of the aft centering ring, and one right into the coupler, hoping that would give me a little extra support on that rail button.

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A month or so later, I decided to install the fins. I skipped the fin jig this time, and just used two pieces of aluminum angle clamped to opposite fins to line them up perfectly. Then I tacked the fins in place with thick CA.

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I was finally able to stack the whole rocket together and see what it would look like. I was pretty impressed!

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I used a dowel rod and Bob Smith 30 minute epoxy to do internal fillets to secure the fins to the motor tube.

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This is why I drilled holes into the fin tabs - I was trying out the "epoxy rivet" method, getting some of the epoxy fillets to go into the holes and act like little fingers, holding the fins to the motor mount.

Because I drilled the holes kind of far up on the tabs, though, I found I had to add a bit more epoxy than I needed, just to get it into those holes (this is the overbuilding I was referring to earlier in the thread). In any case, it might be heavier than it needs to be, but should be secure (I hope)! I watched each set of fillets for about 10-15 minutes, and cleaned up any epoxy that oozed over the sides, cleaning up any unwanted drips with rubbing alcohol.

Once all the internal fillets were cured and done, I ran a ring of epoxy around the inside of the airframe and the outside of the motor tube, plus a little on the aft ends of the fin tabs, and pushed the aft centering ring in place to get a nice, tight fit.

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I then put JB Weld epoxy on the outside of the motor tube and a fillet of Bob Smith epoxy around the centering ring, and attached the motor retainer. I didn't take a picture of this, but this post on my Nike Smoke build is exactly the same process.

Then I inverted the rocket for the aft CR epoxy fillet to cure.

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Months later, when winter had come and gone, I went outside and coated the whole rocket in two light coats and one really thick coat of primer.

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I have one too, actually two. And instead of buying two, get the longest one, and cut it into two pieces, one about 8" and to the other is about 18" long. They're also great at making axial lines on body tubes, and used as a cutting guide for fin slots..

OK, after listening to you two talk about this great tool, I went over to Amazon.com and looked for it, and found FOUR different lengths... 5", 11", 18", 33" and one "gift pack" that was the 11" and two "rolls" of 220 and 150 grit.

So I decided to pop for the gift pack to try this thing out. Plus, by going over to my favorite podcast, I found if I order the $20 gift pack through their link to Amazon, they get a cut of the money and helps them out as well!
 
OK, after listening to you two talk about this great tool, I went over to Amazon.com and looked for it, and found FOUR different lengths... 5", 11", 18", 33" and one "gift pack" that was the 11" and two "rolls" of 220 and 150 grit.

So I decided to pop for the gift pack to try this thing out. Plus, by going over to my favorite podcast, I found if I order the $20 gift pack through their link to Amazon, they get a cut of the money and helps them out as well!

It's my favorite tool in the kit. You'll love it.
 
I kept checking both the weight of the rocket and the CG throughout various phases of construction. One thing I did not photograph was fin fillets. I made them small, with Bob Smith 30 minute epoxy filled with microballoons.

Oddly, though, the weight did not seem to increase with the addition of fillets, and the CG didn't budge at all. This was really surprising. Yes, my scale is calibrated, and I found the CG by balancing the rocket thusly.

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I don't know how to explain it, except that I kept the external fillets really small and mixed the microballoons in till I had a really thick paste. Perhaps that was enough that there really wasn't much epoxy in the end fillets.

Anyway, once the rocket was primed and sanded, I looked closely at the fins. Despite having filled the wood grain with CWF, there were some areas where it showed through. It had been a long time since I applied the CWF, and maybe some of it got knocked out.

I circled all the grain spots, so I wouldn't miss any.

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I decided to try filling the imperfections with Bondo Spot and Glazing Putty, something I'd heard good things about here on TRF.

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It was pretty easy to use - just smear a little on with the tube, and spread it flat with a putty knife, removing excess.

I also decided to see if I could hide the gap between the forward and aft body tubes, with some thick CA.

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I'd sand this off, then re-prime. I wasn't sure how well it would work, since the two airframe tubes weren't a perfect match in all places, but I wanted to try it. I got really good results with this when I built an Astron Sprint XL, hiding the joint between the body tube and the plastic airframe. On that rocket, it all looks like one piece.

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Next up: CG adjustment
 
Once I sanded down the CA and Bondo, I re-primed it, and gave a final sanding, ready for paint. Then I checked the CG, and plugged that into my sim. The rocket with no motor was over 1 caliber stability, but less than 2. With a G40 installed it was really marginal. According to my sim (and my technique of laying the unopened motor onto the back of the rocket with the CTI casing in the motor tube), with an H133, the rocket would be so close to neutral, I knew I had to do something.

I played around with the sim and the real rocket, and found that a mere 18 grams of nose weight would do the trick. I decided to go with modeling clay, since it's what I had on hand.

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Rolled up into a snake and rammed into place with a dowel, the nose weight made the rocket safely above 1 caliber with motor installed.

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If it seems like the clay is starting to come loose, I'll dribble a bit of epoxy in there, but for now it's pretty darned secure.

Next, I have to decide what colors to paint this darned thing. After nearly a year, I haven't figured that out.

My decision: Keep it simple.
 
I went with a base coat of Rustoleum 2X Flat Black - a paint I really like. Always goes on nice, and makes the rocket look big with it's flat surface color.

My painting booth is a cardboard box from a giant cooler. It's pretty big, but the rocket is slightly too tall for me to paint the whole thing. I put the nose cone onto a wand on my lazy Susan painting stand.

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Did the whole rocket up in flat black. Then masked...

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Now, the striptease...

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Aaaaand... done!

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Finally finish everything with some black rail buttons from rail-buttons.com. I ordered them for this rocket, because I only had white, and decided they should match.

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I really love the way this rocket turned out. Can't wait to fly it. Will do my cert flight on a CTI H133 with a chute release, probably set for 400 feet.

Such a beautiful thing!

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Then, I moved on to finish my Nike Smoke...

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That is a simple and elegant paint job. Very nice!

I need to experiment with flat paints a bit...

Thanks!

The Rusto 2X flat black and flat white are two of my favorite paints. They always go on nice and smooth, and look great. I never get any orange peel, or worse - those spiky chunks you sometimes get with their gloss paints. The horror that happened to my Ventris yesterday... I can't think about it...

I've even (gasp!) put waterslide decals on the white, with no peeling or silvering over time (which I know you're not supposed to do, but I did it anyway). It's a nice, smooth paint.

The downside - it is a bit of a dirt catcher. The black shows dust like crazy, and the white does get smudges if you give it a dirty look. But that all wipes of easily.
 
And here's the successful cert flight, September 17, Amesbury, MA. Motor was a Cesaroni H133 with a 9-second delay. Really kicked!

[video=youtube;or7M_K0eCGA]https://www.youtube.com/watch?v=or7M_K0eCGA[/video]
 
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