Ukranian R-360 Neptune

[jqavins]

I have had a bunch of rockets with 2-3oz in nose to stabilize them (I use 2 and 3oz fishing weights or sometimes a nose-full of pennies). The challenge becomes getting a big enough chute in there so it comes down at a reasonable speed. I don't love putting that much weight in the nose but it is sometimes necessary to make a missile that has active guidance in the real world stable with just BP rocket engines (particularly give the weight of the 3D printed parts near the rear of rocket). That is why I put 24mm motor mounts in here.

Based on the 5:1 T:W rule of thumb, your thrust number will need to be five more than the rocket would need without that 2.5 oz. A trap to watch out for is that that can mean a bigger, heavier motor, which necessitates more nose weight and still more thrust in a vicious cycle that leads to HPR. But since you've already got rockets with this much nose weight, I guess you already know that you're not there.

Check the rod exit speed in the sims, then push the button.

(Can the 3D printed parts be lightened any? That would certainly help stay further away from the trap, and further up in the sky.)

 

[BigMacDaddy]

Rough fins made this morning... Need to grade papers today so probably not going to have time to do more till tonight or tomorrow... Also made fins and centering rings for my Big Daddy slight upscale.

 

[BigMacDaddy]

Based on the 5:1 T:W rule of thumb, your thrust number will need to be five more than the rocket would need without that 2.5 oz. A trap to watch out for is that that can mean a bigger, heavier motor, which necessitates more nose weight and still more thrust in a vicious cycle that leads to HPR. But since you've already got rockets with this much nose weight, I guess you already know that you're not there.

Check the rod exit speed in the sims, then push the button.

(Can the 3D printed parts be lightened any? That would certainly help stay further away from the trap, and further up in the sky.)

Yeah, I am pretty conscious of those thresholds since I have gotten close before... The D12 engine has a great thrust to weight ratio so gives pretty good margin. I am going to add the pod on the bottom of the design so that I can use rail launch w/ lug on pod and on fatter booster (just going to make the pod stick out as much as the booster). This also gives me added length (close to 1.5m if I use my Makerrail and 2m if I use my 2020 rail). w/ 1.5m I am getting 17.5m/s off rail.

Probably going to downsize sustainer motor since I do not want to lose it. D12-0 + C6-5 seems like a nice flight. 18" parachute in sustainer seems to be enough for slow enough landing. Of courses these are not final weights so once built I will enter correct weight and CG location to see how much weight is needed in nose.



I do always try to keep weight down on the 3D printed parts but if it gets really close I can usually drop even more weight (for example, go to 2 layers instead of 3 for surfaces).

 

[Pem Tech]

Man, I am so behind the curve on this thing. Nice looking missile. So Jim Flis has already built this one? Would love a flight report.

 

[jqavins]

The pieces pop off while cutting if you do not put tabs and then get chewed up by router...

I wonder if that could be addressed by double sided tape.

 

[BigMacDaddy]

I wonder if that could be addressed by double sided tape.

Ah, yes for sure... I just am lazy about taping...

 

[OzHybrid]

The pieces pop off while cutting if you do not put tabs and then get chewed up by router (actually one piece still popped off because middle of boards flex which can result in tabs being cut through - thankfully it popped away and did not get gouged). Normally I try to make the tabs half the thickness of the wood but in this case I cut two 2mm pieces of wood at once so more or less full thickness tabs that I need to cut.

Ive switched to the blue 3M tape and superglue method of hold down. Tape on bed,. tape on bottom of work, then zig zag of superglue and place together. No more clamps to hit.
Norm

 

[OzHybrid]

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?

Or the Exocet.
.
Norm

 

[BigMacDaddy]

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?

Apparently, it does do Sea skimming -- at least looks like it in the video of it being paced by a fighter plane.

Interesting video about the ship being sunk...

 

[aerostadt]

If you think about it, using vertical thrust to overcome gravity in a hovering manner is a very efficient process. Just sit down and do some calculations for a man hovering with a hydrogen peroxide rocket motor/jet pack on his back and you will find that you can only hover for a minute or two. Now, take 2 bullets and simultaneously drop one bullet and fire the other bullet horizontally at the same time. Both will hit the ground at the same time. Of course, the bullet fired from the gun will go a lot farther horizontally, but they still have the same very short flight time. However, if the bullet had very small fins to deflect or change a very small amount of its horizontal velocity into a very slight vertical velocity component, it would have that extra small velocity for free fall in the vertical direction and, hence, could go a lot further horizontally. When I first saw the Exocet missile 40 years ago being used in the Falklands War, I realized that its fins/wings were way too small to create any substantial lift. Therefore, this missile must be using an altimeter to know its height above the ground and to deflect a tiny part of its trajectory upward, so that the horizontal travel distance is greatly extended.

 

[Brainlord Mesomorph]

I will have to do the fins tomorrow -- too late to start up the CNC... May shorten the coupler insert between stages (worried it might catch).

given my static tests on the power of the EC, I don't think you have to worry, that looks fine

 

[Brainlord Mesomorph]

deleted double post

 

[Brainlord Mesomorph]

If you think about it, using vertical thrust to overcome gravity in a hovering manner is a very efficient process. Just sit down and do some calculations for a man hovering with a hydrogen peroxide rocket motor/jet pack on his back and you will find that you can only hover for a minute or two. Now, take 2 bullets and simultaneously drop one bullet and fire the other bullet horizontally at the same time. Both will hit the ground at the same time. Of course, the bullet fired from the gun will go a lot farther horizontally, but they still have the same very short flight time. However, if the bullet had very small fins to deflect or change a very small amount of its horizontal velocity into a very slight vertical velocity component, it would have that extra small velocity for free fall in the vertical direction and, hence, could go a lot further horizontally. When I first saw the Exocet missile 40 years ago being used in the Falklands War, I realized that its fins/wings were way too small to create any substantial lift. Therefore, this missile must be using an altimeter to know its height above the ground and to deflect a tiny part of its trajectory upward, so that the horizontal travel distance is greatly extended.

Look how the engine is offset ventrally, hows there's extra wieght on the bottom and what are all those little holes?

 

[rharshberger]

Look how the engine is offset ventrally, hows there's extra wieght on the bottom and what are all those little holes?

i wonder if the holes a flow through cooling.

 

[aerostadt]

Look how the engine is offset ventrally, hows there's extra wieght on the bottom and what are all those little holes?

Obviously, there is a covering over the aft-end of the turbo-fan engine. There is a protrusion on the covering for the aero-spike part of the nozzle exit. The original Exocet weighed about 1,700 lbm, had a solid propellant motor, and a range of 25 to 43 mi. depending on the launching aircraft(all according to Wikipedia). The range of the later versions of the Exocet were greatly extended by incorporating a jet engine. According to Google/Wikipedia the weight of the Neptune is about 1,900 lbm and the range is 190 mi. I think that I have seen longer ranges reported.

 

[BigMacDaddy]

Probably uses Engine-Driven Gas-Dynamic Stabilization

 

[BigMacDaddy]

Finally got the first prototype more or less built completely...

 

[Ez2cDave]

Finally got the first prototype more or less built completely...

This looks very interesting !

Dave F.

 

[BigMacDaddy]

Updated simulation as built...

 

[cls]

Regarding the booster recovery... It looks stable with those fins and the burnt motor. So I bet it will just fly in to the ground. Might be ok in tall grass.

With a little less fin, and the motor weight moved aft, it could probably be made unstable, for tumble recovery. Might be ok in tall grass, but yeah those fins seem likely to break...

A quandary for sure...

 

[BigMacDaddy]

I fly in a muddy field so usually rockets and fins just stick in the mud if there is a failed recovery or fast descent. If the booster comes in too hot, I will try splitting the front cap on the BT-80 and the joiner portion that goes into the sustainer. Then will try to get a small parachute in there tied to those parts. Worst case I will need to split the whole BT-80 tube and front cap / portions to make them peal away from motor tube and rear cap / retainer.

 

[jqavins]

What about kicking the booster's motor mount aft the way some gliders do? Shift the free booster's CG back so it becomes unstable.

If you've said, I don't recall: how much nose weight is in there to keep the sustainer stable? Can you show the OR design screen for the sustainer only? It looks like the CP on that would be really high. It looks like it would need a piano in the nose.

 

[BigMacDaddy]

What about kicking the booster's motor mount aft the way some gliders do? Shift the free booster's CG back so it becomes unstable.

If you've said, I don't recall: how much nose weight is in there to keep the sustainer stable? Can you show the OR design screen for the sustainer only? It looks like the CP on that would be really high. It looks like it would need a piano in the nose.

This is with 2oz of weight in nose...

 

[Grant_Edwards]

Someone was saying that this was the missile that sank that ship but others were arguing that it was just an explosion / fire that sank it.

Most western sources say missile, Russia says no missile, just a fire and explosion. Like that's somehow less embarrassing than being sunk by a missile strike?

 

[jqavins]

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.

Most western sources say missile, Russia says no missile, just a fire and explosion. Like that's somehow less embarrassing than being sunk by a missile strike?

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.

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

 

[BigMacDaddy]

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.

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]

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!

 

[Dragon127]

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]

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.

 

[BigMacDaddy]

Figured this guy deserves a paint job (at least a rattle can)... I am not 100% sure that the booster is actually red (might just be a light reflecting on the orange in one picture but it looks more interesting with the two colors).