Ukranian R-360 Neptune

BigMacDaddy

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Looks like an 18×70 mm engine in a 24×95 MMT.
(mumble mumble. CG looks about midway between MMT and tip of nose. mumble. E12 weights 35 g more than C6. mumble. bit over an ounce. mumble mumble.)
So, balanced to take an E12 if might need a little over three ounces of nose weight, maybe 3½. I guess that's still a few grams short of a piano.

Yeah, I wondered about that too. A fire broke out. Our crew took too long to put it out and/or our ship design let it reach the explosives too easily, so it blew up. And that's so much less humiliating than being hit by a Ukrainian missile or two. :questions:

Are you listening, President Putin? The world is laughing at you.

Yes, built for a 24x70mm mount (D12-5) but will take a 18x70mm motor (I design my motor mounts in a way that lets me use an adapter to downsize to 18mm in the same length space). I already risking losing this with a D12-0 booster and C6-3 sustainer so not likely to go larger.

I just posted a request for a feature in Open Rocket. It would be great if you could override CG and mass but check some elements to be excluded from the override -- In this case, it would be great to be able to change engines and then modify the nose weight to see how heavy it would need to be for a D or E engine.
 

boatgeek

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Nice looking model.

I was wondering how the Neptune compares to the US Harpoon. Does the Neptune do sea skimming?

It seems impressive to sink such a large vessel with only two missiles. Large ships have many sealed compartments and to sink one you have to puncture and flood a lot of compartments. Did they just get lucky and hit the ammo magazine?
Way late on this response, but this is literally what I do for a living (though mostly on commercial boats, not Navy).

A warship the size of the Moskva should be able to survive 2-3 major compartments flooding (near amidships where the missiles hit--towards the ends there's more factors). In theory anyway. In practice it gets weird:

* Watertight doors between compartments only work if they're closed, and it's a hassle to close them after every time you go through. Did the crew keep them closed all the time/close them after evacuating the compartments?
* Watertight doors can be finicky, and shock might make them fail to seal, especially if they're not maintained well.
* There was enough flooding that some of the windows were underwater. If the glass was broken and the closure behind wasn't sealed, water might have come in there.
* Fires can break watertight seals, either by causing structural damage, burning the gaskets, or deforming the steel enough that things don't seal anymore.
* Fighting a fire with water means pouring lots and lots of water into the boat. If you don't have the bilge pumps running to empty that water out, you can easily sink a boat by fighting a fire. Good news, the fire is out, bade news, the boat's on the bottom.
* Shock can break pipes in the next compartment over and cause pretty major leaks.
* Boats tend to get very unstable when there's a lot of water sloshing around inside. It could have just rolled over.

Anyway, very nice model, looking forward to seeing it fly!
 
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Nice work!
I would be happy to print these and give you my feedback, if you have not found someone yet. I have both filament and resin printers of differing sizes.

Cheers Rob.
 

BigMacDaddy

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Finally had a chance to launch this today... Flew pretty well on a D12-0 + C6-5. Parachute ejected but got tangled or for some reason did not open but no damage to rocket despite falling from 300+ feet.



Booster came in a bit hard and one fin got a little damaged. Will try the split nose and streamer on the next version.
 

neil_w

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Finally had a chance to launch this today... Flew pretty well on a D12-0 + C6-5. Parachute ejected but got tangled or for some reason did not open but no damage to rocket despite falling from 300+ feet.



Booster came in a bit hard and one fin got a little damaged. Will try the split nose and streamer on the next version.

How big is that field? What town?

Looks like a nice place to fly but hard to judge size from the wide-angle camera.
 

neil_w

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That’s a really good size, better than anything I have around here. One day maybe I’ll meet you there (although then you’d have to tell me where it is. :))
 

BigMacDaddy

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That’s a really good size, better than anything I have around here. One day maybe I’ll meet you there (although then you’d have to tell me where it is. :))

They are about to setup a carnival there so I am glad I went when I did!!! Would be great to get together. I need to start going to club launches -- I get too stressed launching in parks (especially with the larger D/E engines).
 

neil_w

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They are about to setup a carnival there so I am glad I went when I did!!! Would be great to get together. I need to start going to club launches -- I get too stressed launching in parks (especially with the larger D/E engines).
I totally understand the stress aspect. That's why I never launch on my own.
 

BigMacDaddy

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This is really fun looking model! The 2-stage motor combination and altitude look very good. Perhaps you could sell these 3D printer designs to some commercial company like Boyce Aerospace.

Thank you -- I do not know if any of those companies purchase or license designs - if someone has advice or a contact I would welcome it.

I am going to post the 3D designs for folks to purchase via Cults. I know there is not much of a market for this type of thing (people would rather buy the whole kit, buy printed parts, or if they have a 3D printer they often design themselves.

What do folks think is a fair price? I was thinking $9.50 for the STLs (I believe that the difference between $5 and $10 is minimal - decision to purchase a design that you will print is the main barrier to adoption I think).
 

aerostadt

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I bought the BigMacDaddy's files from Cults and sent them to a 3D printer company. I am in the process of putting the parts together now. I have a number of projects keeping me busy this summer, so my progress on the Neptune has been slow but steady.
 

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aerostadt

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I am making pretty good progress on BMD's Neptune. I had to sand, file, and Dremel sand a few parts, but it was easy. The inter-locking parts took a little bit of filing on the locking tabs, but now work good. I found concentric fitting tubes that will hold the 24 mm motor at Balsa Machining Services that I am using for the first stage. I am thinking of putting in a small electronic unit into the first stage for recovery, but I am currently having trouble with the electronics.
 

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BigMacDaddy

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For those interested (and that missed it) I am selling the 3D printed parts to make this rocket for $30 + shipping.

I posted a new thread here:
 

aerostadt

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I have constructed an electronic chute ejection for the first stage of Big Mac Daddy's Neptune. Things are a little bit tight and make use of body tubes that are BT-50-ish in size. The motor mount tube has an engine block and still uses BMD's interlocking aft-end system. I used Balsa Machining Services BT-50-ish concentric tubes so that the upper lid of the first stage will fit into the motor mount tube. There is a tube for the small Bear River Altimeter from Boris du Reau. There is a small tube for the 1S Lipo battery and there is a tube for ejection charge. Some of the tubes are made from the short Estes motor spacer tubes that Estes offers in their kits. I had to put some notches in the first stage upper plastic lid in order to fit over some of the tubes on the peripheral edges. The tube that contains the altimeter has a hole to the outside to sense air pressure. The altimeter tube and the battery tube have holes in their lids for the electrical lids. I plan to plug the holes with poster putty. I haven't tried this, yet, but it looks doable.
 

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BABAR

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Cool rocket. I am likewise very late to the party.

putting an A8-5 in the sustainer gives three potential advantages. (Maybe A8-3, 5 seconds may be long, especially as it looks kind of draggy, not sure if sims will effectively demonstrate this.)

lower mass than the C6, so should improve your CP for better stability.

shorter thrust than the C6, so unless you really WANT more altitude and possible a longer walk (or higher chance to lose it if it weathercocks) you still get all the excitement of a staging event without the above issuse.

larger bore than C6 (although obviously you were already successful staginwith the smaller bore, so not a big deal.). I have no empiric evidence, but logically seems like upper stage ignition (particularly with any significant gap) is more reliable with a larger sustainer motor bore.
 
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