SAM-N-8 Zeus

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Another little known thing, of which once again Designation Systems Net is the only real resource.

Copy of a xeroxed copy found in NHC files:

Naval Aviation Confidential Bulletin January 1949 - - - CONFIDENTIAL

ORDNANCE *

GUIDED MISSILES

ZEUS I LAUNCHED FROM 8-INCH GUN

On 15 September 1948, a guided missile was launched from a gun and deflected around a corner for the first time in the history of naval ordnance. This experimental missile, formerly called the Gun-Launched Guided Missile—Arrow Shell, has recently been named Zeus I by the Munitions Board and designated XSAM-N-8. The Naval Ordnance Laboratory is developing it under the sponsorship of the cognizant branches of the Research Division, Bureau of Ordnance.

Advantage over Conventional Projectile—The present experimental missile, which is fired from an 8-inch, smooth-bore gun, is fin-stabilized in flight rather than spin-stabilized. This reduces the drag and gives the missile, in comparison with the conventional 8"/55 projectile, a shorter time-of-flight to any slant range if it is used as an antiaircraft missile, or a longer range if it is used for bombardment. Although the fins of the missile are 8 inches in diameter, the body is saboted down to 4 inches. The design is thus lighter in weight than the standard 8-inch projectile and achieves a much higher muzzle velocity with the same powder charge. With 75 pounds of powder a muzzle, velocities of 3,150 feet per second have been obtained; with 100 pounds of powder, velocities of 4,000 feet per second.

Another advantage of the fin-stabilized missile is that it is not sensitive to the L/D (length/diameter) ratio. The present 8-inch Zeus I has an L/D ratio of 10, and calculations have shown that an L/D as high as 20 could be used without impairing the stability of the missile. The results of firing to date also indicate that the fin-stabilized missile has a smaller dispersion than the corresponding spin-stabilized Projectile.

Calculations show that if the Zeus I (the Arrow-Shell) is used without guidance, it has a greater single shot kill probability (S. S. K. P.) against maneuvering targets and a greater effective range than any of the present antiaircraft projectiles. However, when one step of guidance is added, calculations show that the S. S. K. P. and the range at which antiaircraft is effective are greatly increased. For example, the S. S. K. P. of the 5"/70. for a certain maneuvering target at 5,000 yards slant range is 0.025, while if one step of guidance is added to Zeus I (the Arrow Shell), its S. S. K. P. is 0.300 or an increase of 1,200 percent. Or to look at it another way, calculations show that for this same maneuvering target, Zeus I with one step of guidance has the same S. S. K. P. at 15.000 yards as the 5"/70 has at 5,000 yards; namely, 0.025. Thus, Zeus I will extend the effective range of antiaircraft fire to three times its present value for this particular S. S. K. P.

The guidance for Zeus I consists of a deflecting charge which is carried in the mid body of the missile and initiated from computers on the ground whenever the angle between the trajectory and the target becomes greater than any predetermined value, in this case 5°. This increases the S. S. K. P. of antiaircraft fire because, if the target maneuvers after the missile has left the gun, an intelligence system—that is, the ground radar and computer—knows where the target is and where the missile must go to secure a hit, and sends a message to the missile when the time has come to trigger the deflection charge. The deflection charge which reacts perpendicularly to the trajectory is sufficient for this weight of missile (72 pounds) to deflect it 5° into the corrected trajectory. The deflection charge produces a side thrust of 60,000 pounds for a period of 0.010 seconds, thus giving a total impulse of 600 lb./sec. to the missile.

Plans are now under way for Zeus II, an Arrow-Shell with guidance and extra propulsion. At the present time, plans call for a study of the possibility of adding some type of rocket propulsion, either solid of liquid propellant to the missile. This would increase the flight velocity over the muzzle velocity, decrease the time of flight to any slant range, and increase the range and the terminal velocity.

Photograph that was with the article (yes, i know, poor quality; but....hey....)
 

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What I could not understand is how the control system knew, how exactly the shell is oriented? Without any kind of roll stabilization, how would the control station understood, at which direction the deflecting charge nozzle is pointed at the moment of activation?
 
Has to be timing.
Likely the deflection charge is always aligned a specific way and thus it's rpm is a known factor. It's thus just a matter of timing the initiation signal to coincide with the moment the rotation brings the charge pointing in the right direction.
 
The control is likely a combination of "Skid to turn" technique and "pif-paf" or "Jet dynamic" system similar to what used in PAC 3 or In Russian 9M96 missiles.

From the description tho, the Russian missile seems to be the closest analogue, with the deflection charge located at mid which, presumably the missile's center of gravity. Unlike ERINT tho, which will provide yaw or pitch moment to help turning. The deflection charge will directly push and turn the Zeus.

I'm curious tho about the possible guidance. Given the concept's age. Command or beamrider would be possibility with tail control. as those might be quite robust, to withstand massive acceleration in gun barrel. More advanced concept could use active radar homing, with canard control, and free to roll tail.
 
stealthflanker said:
The control is likely a combination of "Skid to turn" technique and "pif-paf" or "Jet dynamic" system similar to what used in PAC 3 or In Russian 9M96 missiles.

From the description tho, the Russian missile seems to be the closest analogue, with the deflection charge located at mid which, presumably the missile's center of gravity.

Aster is similar.
 
zen said:
Has to be timing.
Likely the deflection charge is always aligned a specific way and thus it's rpm is a known factor. It's thus just a matter of timing the initiation signal to coincide with the moment the rotation brings the charge pointing in the right direction.

Hm... a probability, yes. Probably wouldn't work every time - a slight out-of-sync and the deflection would be in a wrong direction - but generally would work.
 
There maybe another option which is as the fins rotate there would be a differential in it's radar reflection.
Depends on the radar though.
 
Six decades later the Italians used the same principle in 76mm guns with the DART munition, for the same purpose (extending AAA effective range).
https://www.leonardocompany.com/en/-/dart-strales-76mm

About the 8" thing; keep in mind the only platform that could have used it were the mere three Des Moines class cruisers.
https://en.wikipedia.org/wiki/Des_Moines-class_cruiser
 
zen said:
There maybe another option which is as the fins rotate there would be a differential in it's radar reflection.
Depends on the radar though.

Actually... interesting possibility! Must admit, that I never thought of that!
 
lastdingo said:
About the 8" thing; keep in mind the only platform that could have used it were the mere three Des Moines class cruisers.
https://en.wikipedia.org/wiki/Des_Moines-class_cruiser

They actually wanted something bigger. There are mentions that they planned to use incomplete battleship "Kentucky", rebuilding her into "anti-aircraft battleship" with three-two quadruple 8-inch RF turrets:

132860_800.jpg


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30138_900.jpg
 
sferrin said:
Would that have been in addition to Talos? :eek:

Basically, it was supposed to be short-range weapon with quick reaction time. Most of missiles of early 1950s were still liquid-fueled, and weren't exactly fast to launch. But then the solid-fuel RIM-2 "Terrier" came, and basically made "Zeus" obsolete in comparison.

But if Navy decided not to make a stopgap SAM out of "Talos" guidance test vehicle (which was exactly how "Terrier" was born), then probably "Zeus" would be deployed instead.
 
I just ran across this project, and think it is another example of potential technological development thought to be a dead end and abandoned too early. We're just now going back to the idea with DART and the guided rounds for the US 5" guns. What might have been with another several decades of development over the intervening years.

What I could not understand is how the control system knew, how exactly the shell is oriented? Without any kind of roll stabilization, how would the control station understood, at which direction the deflecting charge nozzle is pointed at the moment of activation?
From the first post: The present experimental missile, which is fired from an 8-inch, smooth-bore gun, is fin-stabilized in flight rather than spin-stabilized. This would require a new gun; the Des Moines wouldn't work as built. They would need smooth bore barrels, but also high elevation turrets.
 
If they're talking about engaging at 15,000 yards, then the 41 degree elevation turrets in the Des Moines class would be adequate against most threats except very high level bombers*. Even low angle guns were useful AA weapons at longer range. Changing the Mk 16 to smoothbore probably wouldn't be too difficult, just swap out the liner for one without rifling, or build them without in the first place.

* And the turrets were designed for AA use, with provision to set the MT fuses on Anti-Aircraft Common shells just prior to ramming.
 
From the first post: The present experimental missile, which is fired from an 8-inch, smooth-bore gun, is fin-stabilized in flight rather than spin-stabilized. This would require a new gun; the Des Moines wouldn't work as built. They would need smooth bore barrels, but also high elevation turrets.

Even with fin stabilization, the shell would still roll in flight. Some active roll stabilization was required. But could the 1940s gyro survive gun launch?
 
Even with fin stabilization, the shell would still roll in flight. Some active roll stabilization was required. But could the 1940s gyro survive gun launch?

Unlikely it seems. The real breakthrough would have to wait until late 1960 or mid 1970's... At that time we reall have the technology for 10000G rated guided projectile.
 
Unlikely it seems. The real breakthrough would have to wait until late 1960 or mid 1970's... At that time we reall have the technology for 10000G rated guided projectile.

It was suggested above that maybe the rotation of projectile could be somehow tracked by radar - maybe with some kind of corner reflector, which gave strongest return signal when it was directly above, or something - so the fire control could actually calculate in which position are shell in any moment.
 
If they're talking about engaging at 15,000 yards, then the 41 degree elevation turrets in the Des Moines class would be adequate against most threats except very high level bombers*. Even low angle guns were useful AA weapons at longer range. Changing the Mk 16 to smoothbore probably wouldn't be too difficult, just swap out the liner for one without rifling, or build them without in the first place.

* And the turrets were designed for AA use, with provision to set the MT fuses on Anti-Aircraft Common shells just prior to ramming.
At 15k yards the estimated chance of an intercept is estimatrded to be 2.5%; the real difference was at 5000 yards where the probability was 30%. Would 41% still be enough elevation at that distance? Or would a 6" round with folding or flip-out winglets work with Worcester class 6" guns, re-gunned with smoothbores?
 
At 15k yards the estimated chance of an intercept is estimatrded to be 2.5%; the real difference was at 5000 yards where the probability was 30%. Would 41% still be enough elevation at that distance? Or would a 6" round with folding or flip-out winglets work with Worcester class 6" guns, re-gunned with smoothbores?

The 6"/47 Mk 16DP guns on the Worcesters only had a maximum elevation of 44.5 degrees, just 3.5 degrees more than the 8" Mk 16 on the Des Moines and while they were designed for 12rpm/gun, they were unreliable, while the 8"/55 Mk16RF turned in a reliable 10rpm/gun.

I can't find the AA ceiling for either mount, but a ROM figure (range * sin elevation - (0.5* 32 fps * time of flight^2) )suggests their AA ceiling at 5000 yards as around 8000ft for the 8"/55 Mk 16 RF and 10,000 ft for the 6"/47 Mk 16 DP (probably on the high side as I'm not allowing for drag/external ballistics). Push that out to 15000yds and it's c27,000ft and c29,000ft. Attack profiles were changing as jet aircraft and missiles appeared, but both vessels had been deliberately designed as capable of anti-aircraft use, yet with those turret elevation limits.

A 600kt target will cover 15000 ft in about 75 seconds. In that time a Des Moines can pump out 12 barrels * 10 rpm/gun * 75/60 = 150 rounds. Even at only 2.5% that's a high chance of a kill. If, more realistically, they fire a box barrage to put 12 shells at 5000 yds as the target arrives, that's 12 30% chances of a hit. And they can potentially do that every 2000 yards from 15000 yards out.
 
One historical irony was that Zeus was not put into service because the USN thought that Talos (which they initially believed would make shorter range AA weapons unnecessary, saving what were in the late 1940s scarce funds) would be in service much sooner, not to mention the school of thought within the navy that held guns were obsolete altogether. Needless to say, fallacy upon fallacy.
 
So to restate the description, the actual missile body is just 4" diameter. Meaning the systems package into this, comprising a VT fuse warhead and a radio command rocket charge.

So with flip out fins, this could be fired from something down to 4.5", if not 4".

At a length to diameter ratio of 10, the dart is 40 inches long? Meaning 3ft 4inches.

If only this was shared with the UK. Imagine combining this with Green Mace. Say pumping out three darts in quick succession.
 
If only this was shared with the UK. Imagine combining this with Green Mace. Say pumping out three darts in quick succession.

Bloodhound was still much better solution, so why bother? Since Green Mace was designed only in 1956, it would took at least two years to actually put her into production - and by that time Bloodhound would already be deployed.
 
If only this was shared with the UK. Imagine combining this with Green Mace. Say pumping out three darts in quick succession.

Bloodhound was still much better solution, so why bother? Since Green Mace was designed only in 1956, it would took at least two years to actually put her into production - and by that time Bloodhound would already be deployed.
Different solutions to different ranges
Zeus is what a 5,000yard system?
Not even close to Bloodhound mki range.
 
Especially if one is priced in dollars.

Yep. And in 1950s, it was generally assumed that future aircraft development would be aimed toward even higher flight speed and altitudes. So, even with guided shells, the Green Mace would be (from the 1950s point of view) a very short-therm measure, which would become completely obsolete in less than a decade. Investing in this complicated weapon was simply impractical.
 
Especially if one is priced in dollars.

Yep. And in 1950s, it was generally assumed that future aircraft development would be aimed toward even higher flight speed and altitudes. So, even with guided shells, the Green Mace would be (from the 1950s point of view) a very short-therm measure, which would become completely obsolete in less than a decade. Investing in this complicated weapon was simply impractical.
Which is why they dropped it and piled what they could on missiles.

If you'd told them that decades later the majority of combat aircraft stayed subsonic for the majority of the time and only rarely strayed above mach 1 let alone mach 2.......
 
If you'd told them that decades later the majority of combat aircraft stayed subsonic for the majority of the time and only rarely strayed above mach 1 let alone mach 2.......

Yeah, the great irony that SAM's, created to combat such high-speed & high-altitude aircraft became the main reason why such aircraft never were actually created)
 
the main reason why such aircraft never were actually created)

Or cancelled before reaching quantity production (XB-70) or had very short service lives (B-58) or niche uses (SR-71).

The irony is that the B-52 continues in service.
 
Regarding the guns on the Des Moines-class cruisers:
View: https://www.youtube.com/watch?v=ICifnf63lCs
The antenna of the gun mount radar can be seen oscillating at around 2:45. Anyone have a reason for this feature? (I’m assuming it’s a search feature, but radars aren’t my forte)
The reason the radar antenna oscillates is that it uses a conical scan pattern to accurately determine target position. The alternative to that is the lobing transmitter, like on say a German Wurtzburg radar, oscillates instead. Here the T/R waveguide is fixed and the dish nurates or oscillates.

COMINCH-P-08-05-15.jpg
 
Oh, was looking at another interesting report as part of research on Project / Operation Bumblebee (Talos and related missiles).

Seems in the early 50's APL Johns Hopkins undertook a project as part of this as it expanded, called the "Missile Feasibility Studies." They looked at several alternatives for shorter range ship and convoy defense against air attack. These included:

5"/38 conventional gun fire
Using Loki unguided rockets
and,
5"/38 using what they called "Angled Arrow Projectiles."

This last sounds a lot like the Zeus round.

Their conclusion was that none of these was a efficient at killing aircraft as a guided missile would be. They recommended development of what they designated the FS-7 (for Feasibility Study) missile. This was a smaller two stage version of Terrier II weighing 550 lbs. complete, and 300 lbs. for the missile after the booster dropped. Diameter was to be 10" and it would be about seven feet long. The range was proposed to be 12,000 yds. at sea level, 10,000 at 25,000 feet.
Control would be using tail control fins.

They additionally cited that while it could be fitted to a DE type ship in lieu of a 5"/38 gun house, the ship would likely need to be equipped with active roll stabilization to allow the system to work as that type rolled sufficiently that it would be hard to keep a FC radar locked on the target with enough accuracy to allow the missile to hit reliably.
 
Oh, was looking at another interesting report as part of research on Project / Operation Bumblebee (Talos and related missiles).

Seems in the early 50's APL Johns Hopkins undertook a project as part of this as it expanded, called the "Missile Feasibility Studies." They looked at several alternatives for shorter range ship and convoy defense against air attack. These included:

5"/38 conventional gun fire
Using Loki unguided rockets
and,
5"/38 using what they called "Angled Arrow Projectiles."

This last sounds a lot like the Zeus round.

Their conclusion was that none of these was a efficient at killing aircraft as a guided missile would be. They recommended development of what they designated the FS-7 (for Feasibility Study) missile. This was a smaller two stage version of Terrier II weighing 550 lbs. complete, and 300 lbs. for the missile after the booster dropped. Diameter was to be 10" and it would be about seven feet long. The range was proposed to be 12,000 yds. at sea level, 10,000 at 25,000 feet.
Control would be using tail control fins.

They additionally cited that while it could be fitted to a DE type ship in lieu of a 5"/38 gun house, the ship would likely need to be equipped with active roll stabilization to allow the system to work as that type rolled sufficiently that it would be hard to keep a FC radar locked on the target with enough accuracy to allow the missile to hit reliably.
Now that sounds familiar
 
They additionally cited that while it could be fitted to a DE type ship in lieu of a 5"/38 gun house, the ship would likely need to be equipped with active roll stabilization to allow the system to work as that type rolled sufficiently that it would be hard to keep a FC radar locked on the target with enough accuracy to allow the missile to hit reliably.
I've seen on more than one occasion that the Mk 13 could slip into a 5"/38 sized hole, I wonder if that really was the case?
 
They additionally cited that while it could be fitted to a DE type ship in lieu of a 5"/38 gun house, the ship would likely need to be equipped with active roll stabilization to allow the system to work as that type rolled sufficiently that it would be hard to keep a FC radar locked on the target with enough accuracy to allow the missile to hit reliably.
I've seen on more than one occasion that the Mk 13 could slip into a 5"/38 sized hole, I wonder if that really was the case?
Consider the for even the single 5/38 pedestals you had a fairly large ammo handing room under it.

Assuming the Weights, datalines, and power line up I dont see why not. The Mk13 was pretty a drop in hole system...

Hmm... The Barabette(?) might stick out a bit since it looks taller then the 5/38 but since it has less mass on top it might even out. Need to know ALL the weights and sizes of both mounts to true know through.
 

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Oh, was looking at another interesting report as part of research on Project / Operation Bumblebee (Talos and related missiles).

Seems in the early 50's APL Johns Hopkins undertook a project as part of this as it expanded, called the "Missile Feasibility Studies." They looked at several alternatives for shorter range ship and convoy defense against air attack. These included:

5"/38 conventional gun fire
Using Loki unguided rockets
and,
5"/38 using what they called "Angled Arrow Projectiles."

This last sounds a lot like the Zeus round.

Their conclusion was that none of these was a efficient at killing aircraft as a guided missile would be. They recommended development of what they designated the FS-7 (for Feasibility Study) missile. This was a smaller two stage version of Terrier II weighing 550 lbs. complete, and 300 lbs. for the missile after the booster dropped. Diameter was to be 10" and it would be about seven feet long. The range was proposed to be 12,000 yds. at sea level, 10,000 at 25,000 feet.
Control would be using tail control fins.

They additionally cited that while it could be fitted to a DE type ship in lieu of a 5"/38 gun house, the ship would likely need to be equipped with active roll stabilization to allow the system to work as that type rolled sufficiently that it would be hard to keep a FC radar locked on the target with enough accuracy to allow the missile to hit reliably.
I managed to find another study on the "Angled Arrows"

 
I just got a copy of U.S. Naval Weapons, N. Friedman from my local library and found the entry on Zeus.

Nothing particularly new but the proposal for the twin 6”/47 DP guns on the Clevelands was something interesting.

Let me know if you guys want me to check out anything else in particular. I have the book for about a month so feel free to ask for me to look at certain pages.
 

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