RadicalRocketry Ukrainian R-360 Neptune - build thread

[afadeev]

I few of us may have noticed a post in Yard Sale section titled <Ukrainian R-360 Neptune 3D Printed Parts (Limited Run)> about a year ago, right after that missile had sunk Russian cruiser Moskva.
I ordered the 3D parts, must have received them soon after, but did not get around to building the kit until now.
Since then, one of our own, <BigMacDaddy>, had expanded his line of 3D printed scale and semi-scale offerings into a full fledged RadicalRocketry business with a portofolio of 9 rockets listed on the web site, and a few more on FB:
https://radicalrocketry.com/shop/https://www.facebook.com/Radical.Rocketry
I finally came around to building this kit, so lets see how that goes.
I've built kits with occasional 3D printed components (usually nose cones or some embellishments), but this is the first time where ALL of the key parts are 3D printed from ABS plastic. That may, or may not, require extra sanding and priming. We shall see.

For starters, here is what you get to work with, and the end result we are aiming for:


I ordered the kit with the optional precut 3-ply plywood fins, so that took care of sourcing material for the three (3) sets of fins that go into the kit.
In addition to that, the build calls for self-sourcing of the following tubes:

• BT-60 (42mm OD) Sustainer (2nd stage) airframe: 336mm
• BT-80 (66mm OD) Booster (1st stage) airframe: 52.5mm
• BT-50 (24mm ID) Booster Motor Mount Tube: 80mm. I doubled the MMT tube requirement by adding another 80mm MMT for the 2nd stage (original build calls for a MMT only in the 1st stage, and using ABS centering rings to secure the 2nd stage motor w/o a MMT).

Surprisingly, I had all of those tubes on hand. BT60 and BT50 I had as leftovers from prior builds and spare parts orders (I have a medium size box of parts, and both were in it), and BT80 was part of an Estes V2 3228 kit in my build pile, from where it has been borrowed.
Otherwise, one can get all those tubes on the cheap from eRockets.

 

[afadeev]

For starters, I cut tubes to size using 2" Zona Tools hand saw.
I don't remember where I got it, but ScaleHobbyist caries them. Mine doesn't get much use and usually sits in the garage, so its a bit rusty, but still cuts paper body tubes, plywood, plastic pipes and other odds and ends as good as new. Very handy tool.

I find the 2" blade particularly helpful in making nearly perfectly perpendicular cuts through the body tubes.
First, I firm-up the sides of the body tube with a layer of blue masking tape to minimize flexing. Tape also serves as a measurement mark and a cutting guide. In the case of particularly flimsy BT80, I also inserted end caps to firm it up:


The same treatment was applied to all the other tubes, and partially pre-assembled kit looks something like the following:


Here is the 1st stage assembled, and getting primed:


I think I will use two (2) sets of 2nd stage plywood fins as is, and will paper the rear long 1st stage fins to add them a touch of extra strength.
The 1st stage fins are likely to take a hit upon landing, and I want to strengthen as much as possible.

 

[Cape Byron]

Subscribed.

 

[afadeev]

A few initial notes about the kit, the 3D parts, and the instructions:

• 3D printed parts are well printed, and well thought out. Layering is even and minimal, ABS plastic sands pretty easily.
  • 1st stage engine funnel doubles as a turn-and-lock retainer. As does the 2nd stage decorative embellishment retainer.
  • 1st to 2nd stage transition coupler fits perfectly, and is cleverly engineered.
• OpenRocket .ork file is included as part of the kit, which is awesome. I will update component weights once I build my kit, and model flying on different motors for different fields. I do this for all my kits anyway, so having an .ork file shared is very helpful.
• 3D printed ABS parts require a bit of extra "prep" work. High level instructions are provided, but you need to figure out how to peel filler layers off the 3D printed components. This isn't hard, but it's something new.
• You can later dissolve filler/scrap layer material in acetone, and use that slurry as ABS glue. I haven't done this yet, as:
  • All 3D printed parts fit nearly perfectly as-is.
  • I am using TiteBond II for gluing paper-to-wood joints, CA for ABS-to-ABS or ABS-to-tube glue joints, and Tamiya primer and white putty for filling in the imperfections and ridges.
  • I am not sure I have any acetone left in the garage.
• I've lightly sanded the 3D printed nose cone with 240-grit paper, and applied two (2) layers of Tamiya white primer on top. It already looks nearly perfect, with a few remaining pin hole and spiral imperfections that may require a bit more sanding and filling, and then it's ready for the final coat of paint.
  • You can see the quality of the 3D printed tail cone/retainer after only one (1) layer of Tamiya white primer. The part will still needs some more sanding and at least one more layer of priming, but it already looks pretty decent.
  • If your standard of perfection is "1 foot away" perfect, then that's about all the prep that's required. If you want to make it better, the sky is the limit.

So far, I've identified only a few things that will require extra handling or deviations from the instructions:

1. I've added a motor mount tube (MMT) that was omitted from the build instructions, and it warrants an additional BT50 to BT60 centering ring. I believe I have a few of those, after buying all sorts of CR assortment spare sets from SiriusRocketry years ago.
2. Rear (small) 2nd stage fins needed to be trimmed to fit into the 3D printed fin base detail/shroud. Easily done.

 

[Cape Byron]

Tamiya primer and white putty for filling in the imperfections and ridges.

Tamiya putty FTW. Excellent for @BigMacDaddy ’s prints.

 

[afadeev]

This weekend is another wash-out for me, so I'm working mostly indoors on whatever I can, with what I've got.

I had started papering 1st stage long fins last night, and after allowing TBII to cure overnight under the cutting mat (to keep them straight), I got them out and starting finishing them, one by one. To prevent paper edges from lifting, and to add additional rigidity to the fins, I planned to apply CA to the edges to seal them. Once I started doing that, CA (inevitably) ran, so I ended up CA-painting the entire surface of the fins. This requires more sanding afterwards (CA dries rock-hard, and somewhat unevenly), but produces the most robust fins in the end.

The picture below illustrates the progress:

1. Top fin has just had its paper overlays trimmed, and is about to get sanded.
2. Here edges have been fully trimmed and sanded (root is the 45-degree edge on top-left corner).
3. This one has been CA-painted, and allowed to fully dry.
4. Bottom one has had CA surface sanded, and a layer of Tamiya primer applied. It's ready to be installed.

After the picture below was taken, the top three (3) fins were brought upto the final prep state of #4, and root edge fin tabs where cleaned up.


Now it's time to work on installing the fins, starting with the 2nd stage airframe.
I proceeded to work on 2nd stage while the 1st stage fins where still being worked on.

For 2nd stage, installing the motor retainer provides an alignment guide for the four (4) fins, fin shrouds (for aft fins), and the position of the conduit (facing downward in the picture below).
I traced out the fin centering lines, the aft fin shroud location, and the started marking the location of each set of fins.
Forward fins start at 15.5cm from front of sustainer tube. Then I measured out the location of the fin tabs, and cut out the fin-tab slots with a 9mm mini-utility knife.
Aft fins are supposed to start at 30.2cm from front of sustainer tube, but after I test-fitted the aft fin shrouds, things didn't quiet align. Aft fin shrouds are intended to dove-tail with the retainer detail elements, so I took those as hard anchor points and re-aligned the placement of the aft fins from the retainer forward. To keep everything simple, I outlined the position of all fins, fin tabs, and fin shrouds on the airframe (pic below).
To keep the airframe centered and later align the fins during glueing, I'm using the Semroc fin alignment guide from eRockets. It's advertised for airframes upto 2.6", but I had used it to align fins on larger airframes as well. It is also a very handy working platform.



Below is the fin jig used for its primary fin gluing purpose.
Gluing all the fins, one by one, will take some time. But that's the price of getting them all on at near-perfect 90-degree angles. One could go faster if you just CA-them by roughly aiming by eye. I choose to take the time here because:

• I have the tools on hand, I have the time, and I have some appreciation for perfectly aligned fins.
• I want to attach the fins via TBII that takes some time to cure. TBII will provide maximum strength for both the fin attachment, and also reinforce the airframe by wicking into paper tube along the length of the fin root.
  • CA is brittle, and requires quick attachment and produces pretty rough alignment outcomes.
  • Epoxy could also work for this purpose, but I really don't want to mix 4-8 batches of epoxy for this job.
  • I may use epoxy to fillet the fins later, for ultimate strength and visual appeal. We shall see about that. Or, I may just have another go at filleting with gap-filling Quick & Thick TiteBond.

 

[afadeev]

OK, lets add fins to both stages!

There are few detailed instructions on where to position 2st stage fins, other than they should mate with the supporting arms that extend from the aft 3D printed centering ring/motor retainer piece. After a few trial-and-error measurements, I've arrived at cutting TTW slots for 1st stage fins between 22.5mm and 7.5mm from the aft end of the 1st stage airframe.
The picture below shows me marking the cutting slots with masking tape, and test fitting the first fin.


Once the fins and supporting arms are permanently glued, it will be nearly impossible to sand the remainder of the 3D printing ridges. After cutting all four TTW mounting holes for the 1st stage airframe, I went back to making the last pass at applying Tamiya putty and primer to smooth over the remaining 3D printing ridges.
Here is the outcome of on two ends of the 1st stage 3D printed parts. Pic on the left show the result of spraying Tamiya primer alone, and the pic on the right is Tamiya primer on top of sanding Tamiya putty. The latter took significantly longer to achieve. Both look nearly identical from a foot away.
I call both of them done, and will stick to just the primer + sanding from here on out.


Lastly, here is what the 2nd stage looks like with all eight (8) fins attached.
The 2nd stage will still need to have the conduit and the lug nuts attached, but those will go on after I'm done filleting the forward fins. There is too little room to work with otherwise.

 

[afadeev]

I got slightly distracted with life, and with an opportunity to finish a few other models and get them to the point where I can apply epoxy fin fillets across three (3) rockets at the same time. Mixing epoxy and working with it requires rudimentary precautions, and is somewhat messy, so I try to do that only when necessary.

And so, fin fillets have finally been added to all 3 of the following:

• R-360 Neptune
• X-wing fighter (#1302)
• V2 (#3228), because it was an early 1st stage airframe donor

Since this picture was taken, another two layers of primer where applied to R-360 Neptune, and it's all white, ready to receive final coats of paint.
Now, onto painting. I'm not certain what color scheme to go with:

1. All white, which is what the "working" model seems to look like.
2. Orange 2nd stage, white 1st stage (as displayed at some museum)
3. Orange 2nd stage, red 1st stage (as may have been one of the test models)
4. Something else?

Suggestions?

 

[Cape Byron]

The orange and white looks good to me.

 

[Hobie1dog]

Orange "For The Win" thanks for all the pictures.

 

[aerostadt]

Mine is all orange, but I like either paint scheme. Don't forget the nose weight. I did that the first time and it was unstable. The second time with nose weight worked great.

 

[afadeev]

She is done - white 1st stage, orange 2nd stage. Silver 1st stage retainer cone.
I might take more pics during daytime, as night-view shots color correct orange into maroon. And flash washes out the details.

Right now she is clear coated and ready to receive water decals, if I can find something appropriate. Either some rotation pattern markings, or "to Russia with love", or "hello Mokva", or "Candygram for Putin" type of lettering. If I can find where to source those.

Either way, I still need to weight the parts, and update the OR model to pack just the correct amount of ballast into the nose cone. Otherwise, she is ready to fly. Though, likely, not before September.

 

[ljwilley]

That Xwing, is it a scratch build or kit of some sord? I want one!!!!

 

[Hobie1dog]

That is too nice to fly.

 

[afadeev]

That Xwing, is it a scratch build or kit of some sord? I want one!!!!

X-wing on the pic is an OOP Estes Kit #1302, aka Maxi-Brute.
It's an up-scaled 24mm motor cousin of an 18mm MMT Kit #1298.
There is also a 29mm motor mount cousin from NCR #3450.

All three are OOP, but all can be hunted down on eBay. Larger ones go for north of $200. How much further north, I'm not certain, since I got mine many years ago, before Covid.

#1302 is a relatively simple, yet fun build. You spend more time working with plastic components, and only wing structures are from balsa (that should be papered, or upgraded to plywood, for strength).
If you want an example of #1302 build that someone is taking to 11, check out the thread below:
https://www.rocketryforum.com/threads/estes-maxi-brute-x-wing-fighter.159922/
a

 

[Ez2cDave]

That Booster configuration is very unusual . . .

Something else that is unusual . . . It's a land-based, anti-ship missile. Usually, that type of weapon is ship-launched.

 

[afadeev]

That is too nice to fly.

Thanks for the complement, but she will definitely fly.
All my rockets do, and most survive to join the flight-proven and ready to go again inventory. Only two have not lived past the maiden flight, unfortunately, both were pretty painful losses (RoachWerks Nike-Hercules being the most recent core sampling event).

Either way, I don't build statues ;-).

 

[Aeva]

Have you flown this? I made plans in open rocket to make my own one but haven't started. I do intend to name it "You Sunk My Battleship"... as a double joke because the launchpad numbers are like coordinates in the board game (eg, 'B4'), plus it actually sunk a battle ship lol.

 

[MarsFire]

Have you flown this? I made plans in open rocket to make my own one but haven't started. I do intend to name it "You Sunk My Battleship"... as a double joke because the launchpad numbers are like coordinates in the board game (eg, 'B4'), plus it actually sunk a battle ship lol.

Which Battleship?

That Booster configuration is very unusual . . .

Something else that is unusual . . . It's a land-based, anti-ship missile. Usually, that type of weapon is ship-launched.

It's honestly not all that unusual. There are a number of dedicated Surface To Ship missiles and also a number of surface launched versions of air launched Anti Ship missiles.


Andrew

 

[Aeva]

Which Battleship?


It's honestly not all that unusual. There are a number of dedicated Surface To Ship missiles and also a number of surface launched versions of air launched Anti Ship missiles.


Andrew

…sorry not a battleship, the missile cruiser, Moskva. (https://en.m.wikipedia.org/wiki/Sinking_of_the_Moskva)

 

[MarsFire]

Cool. That's what I thought you ment, but just making sure.


Andrew

 

[bad_idea]

…sorry not a battleship, the missile cruiser, Moskva. (https://en.m.wikipedia.org/wiki/Sinking_of_the_Moskva)

Revell has a model of it: