Some Interesting Military Data

[Timerover51]

I mentioned in another thread of how Raphael Semmes, Captain of the CSS Alabama, added a lot of sludge to his memoirs of service in the Confederate Navy. He did do quite a lot of whining in the book. The following is an example from when he brought his first raider, the Sumter, into the British Port of Gibraltar. The quote can be found on pages 329 and 330 of the copy that can be downloaded from Project Gutenberg.

It has been seen, in the course of these pages, how often I have had occasion to complain of the conduct of the Federal Consuls, and one can scarcely conceive the trouble and annoyance which these well-drilled officials of Mr. Seward gave[Pg 330] me. I could not, of course, have complained, if their bearing toward me had been simply that of open enemies. This was to be expected. But they descended to bribery, trickery, and fraud, and to all the other arts of petty intrigue, so unworthy of an honorable enemy. Our Southern people can scarcely conceive how little our non-commercial Southern States were known, in the marts of traffic and trade of the world. Beyond a few of our principal ports, whence our staple of cotton was shipped to Europe, our nomenclature even was unknown to the mass of mere traders. The Yankee Consul and the Yankee shipmaster were everywhere. Yankee ships carried out cargoes of cotton, and Yankee ships brought back the goods which were purchased with the proceeds. All the American trade with Europe was Yankee trade—a ship here and there excepted. Commercial men, everywhere, were thus more or less connected with the enemy; and trade being the breath of their nostrils, it is not wonderful that I found them inimical to me. With rare exceptions, they had no trade to lose with the South, and much to lose with the North; and this was the string played upon by the Federal Consuls. If a neutral merchant showed any inclination to supply the Sumter with anything she needed, a runner was forthwith sent round to him by the Federal Consul, to threaten him with the loss of his American—i. e. Yankee—trade, unless he desisted.

The book may be downloaded here.

http://www.gutenberg.org/files/34827/34827-h/34827-h.htm

It is not near as useful or as good a read as U.S. Grant's memoirs, also available on Project Gutenberg here.

http://www.gutenberg.org/ebooks/4367

 

[aramis]

[m;]Timerover - DO NOT PUT WORDS IN ANYONE'S MOUTHS.[/m;] Misquotes like that are personal attacks.

The 1940's radars' PoD rates were half those of korean era, according to the korean era navy manuals.

The Surface Radars in the early war had major issues with false returns from the surface, false returns from weather, and false returns from signal noise in the installations.

Just because it's crappy doesn't mean it's not useful. Coupled with good sonarmen capable of using the differential hydrophone techniques (port side in left ear, starboard side in right ear), they gave a rather unreliable but useful return. The sonarmen could usually tell you what was at that spot (within reasonable accuracy), but the radar could tell you more accurately (±2 to ±4 wavelengths) where it was...

Even the Vietnam era was a whole different ballgame on radars than WW II... and modern sea surface radars are rather impressive and again a different ballgame. (I got to see them in use on army watercraft in 1987... you can actually get the Active Search Radar to resolve the class from the return alone. ANd it passes that data to the sweep screen for labeling.)

Given the choice of no radar, no sonar, or neither, I'll take the sonar before Korea, and the radar after... but preference is for both in all timeframes.

 

[Condottiere]

For the Battle of Britain, the RAF had a pretty good idea what large returns meant, since the Germans were likely only coming from a limited number of directions, and it allowed them to get their interceptors in place.

Whereas without radar, Goering was probably correct that large numbers would overwhelm them and quite likely catch many of the planes still on the ground.

Radar allowed the RN ships to shadow German warships larger than themselves, and call for backup, with a lot less risk of them slipping away.

 

[aramis]

For the Battle of Britain, the RAF had a pretty good idea what large returns meant, since the Germans were likely only coming from a limited number of directions, and it allowed them to get their interceptors in place.

Whereas without radar, Goering was probably correct that large numbers would overwhelm them and quite likely catch many of the planes still on the ground.

Radar allowed the RN ships to shadow German warships larger than themselves, and call for backup, with a lot less risk of them slipping away.

Neat thing about low POD and large numbers...

Non-detection is a fraction with an exponential function; Probability of non-detection to the power of the number of targets per unit time. Even with shitty 1940 radars, you essentially can't miss a fighter wing long enough to matter. You can miss a battleship long enough to have fog of war, but not long enough for it to get away. Over unit time, you get to raise the power again... so POD=1-((PO!D)^(time_units * number_of_targets))...

Modern radars pretty much don't miss anything larger than their wavelength.

The best stuff that's been publicly released is CIWS hitting a 2cm target at 2km with ≥90% accuracy with a 20mm autocannon... And that's the 90's era data. It HAS been improved, but how much improved is classified.

 

[Condottiere]

There seems to be some pessimism regarding their ability to deal with large numbers of kamikaze speedboats and missiles, though I get the impression even a small number represent a challenge; the fault may lie more with stopping power, range and reaction time, rather than accuracy.

 

[aramis]

There seems to be some pessimism regarding their ability to deal with large numbers of kamikaze speedboats and missiles, though I get the impression even a small number represent a challenge; the fault may lie more with stopping power, range and reaction time, rather than accuracy.

Given 1995 (nominally TL8) released CIWS capability (2cm @ 2km, or 1/100,000, or 2 arc seconds), no missile should survive a turret laser dedicated to killing it by TL A+... since sensor acuity extends range by roughly a power of 10 per TL

Realistically, the lasers can hit it at 1.5 LS. The question set really is,

• "distance before energy density drops below damaging?"
• Ability to put beam into the probable location sphere in time?
• Ability to react before it leaves the focal array's sweetspot for the current range?

A roughly 1 m diameter beam (standard turret lasers) focusing on a 10cm diameter x1 m cylinder, and the cylinder being 6G, you need to get a shot into overlap... if it takes 0.1 sec to bring the beam on target, you've got roughly a 0.1m deviation from expected location at point blank.... at 0.1LS, you now have 0.3 sec aim time, and that missile may be up to 5.4m off from LKP at aim... At 0.05 LS distance and 0.05 sec point time, you get 0.15 sec, and it can be up to 67cm off where you thought when you started the aim.

that takes 1 shot per missile at half a hex...

If the ROF is 1 per 3.5 sec (as per MT), then it's pretty easy to overwhelm. more than 1 per laser and you get at least one through.

 

[JimMarn]

From what I read of WW2 anti-aircraft methods, the Japanese overwhelmed the US Navy's ability to knock down aircraft coming in for an attack. They, I don't know if they knew this or not, sent more aircraft than an individual ship could handle and knock all of them down and not take hits.

Thats why you see anti-aircraft, 20mm and 40mm, gun equipped cruisers defending aircraft carriers. And new aircraft carriers with the sides of the flight deck being lined with 40mm dual and quad mounts. With 20mm mounts in there to. In the early part of the war, the AA was mostly .50 inch machine guns and 1.1 inch machine guns. The fuses on the later were awful which is one reason such guns werre removed and 20mm and 40mm added. The 1.1 inch guns jammed to. Not something you need when over a dozen aircraft are coming in to attack the ship you are on.

Early Home Chain radars didn't have elevation, just distance and bearing. Knowning elevation is paramount is being able to jump the enemy aircraft from out of the sun. The British compensated by having their fighter wings go to higher than the ground controllers estimated the Luftwaffe was flying at. There were ground peope who visually checked elevation, direction, and speed, their info telephoned in to ground controlelrs helped.

And early US Navy shipboard radar was very bad and failed often. It improved as time went by in WW2. But the early stuff... very bad. The British came up with the resonating ah, I forget the term. When the war ended, they wound up in early microwave stoves. By 1944 the US had very excellent radar. We were told this stuff in my US Navy radar tech classes in 1968-69.

 

[aramis]

The Cavity Magnetron, sometimes Resonant Cavity Magnetron, was the definitive solution to getting the microwave radar. And the Radar Range Oven... Now called the Microwave oven, the nuker, or any of a half dozen other nicknames.

 

[Condottiere]

Ideally, a Boforesque forty millimetre; though the idea was to throw off their aim, and for that, you added tracers so that they know they're being shot at.

 

[JimMarn]

The Cavity Magnetron, sometimes Resonant Cavity Magnetron, was the definitive solution to getting the microwave radar. And the Radar Range Oven... Now called the Microwave oven, the nuker, or any of a half dozen other nicknames.

Yeah, thats it. I used to work on a radar that used one. I'm surprised I couldn't remember the name. But then again, that was over 40 years ago.

 

[JimMarn]

Ideally, a Boforesque forty millimetre; though the idea was to throw off their aim, and for that, you added tracers so that they know they're being shot at.

Throwing off aim was good, until the Japanese changed tactics. Then the aircraft had to be shot down before it hit the ship.

 

[BlackBat242]

Throwing off aim was good, until the Japanese changed tactics. Then the aircraft had to be [strike]shot down[/strike] broken up before it hit the ship.

There were a number of instances where a kamikaze aircraft missing major pieces (such as a main wing) still hit its intended target and did significant damage - which is why the USN began replacing the quad 40mm Bofors mounts with twin 3"/50 mounts on light cruisers and above (and some destroyers) as soon as the war ended.

 

[JimMarn]

There were a number of instances where a kamikaze aircraft missing major pieces (such as a main wing) still hit its intended target and did significant damage - which is why the USN began replacing the quad 40mm Bofors mounts with twin 3"/50 mounts on light cruisers and above (and some destroyers) as soon as the war ended.

I don't remember seeing those, but I did see some older DDs with twin 40mm Bofers on them. There were also some FRAM conversions. A small hanger that held a remote controlled flier that could drop 2 depth charges. Basically a frame with counter rotating props on top with the depth charges on the bottom. I think they used a tv screen to see the area near the remote flier. Basically an early drone.

 

[Enoki]

In terms of Traveller we're really looking at (loosely) a TL 5, 6, 7, 8 fire control problem and seeing the results.

At TL5 (pre WW 2) the AA gun is manually aimed. It might have an analog director that predicts the target's movement to improve accuracy. A 6 gun battery of heavy AA guns versus a period aircraft would need to fire about 400 to 600 rounds to shoot it down.

At TL 6 the gun is now director controlled with an electro-mechanical analog computer. Accuracy has improved to a point where 300 to 400 rounds would do the job.
Towards the end of this period, you get stuff like the US M2 90mm with SCR 584 radar and fire control system with VT fuzes. Now 4 guns with 200 to 300 rounds will take down an airplane.

At TL 7 adding increased rates of fire with automatic loading and better VT fuzes takes it to 150 to 200 rounds per gun.

At TL 8 a fully electronic computer with better radar and a fully automatic gun make it possible for 1 or 2 guns to destroy the target in less than 100 rounds, often less than 50.

Again, in terms of Traveller, you should see the same sort of exponential increase in effectiveness of most weapons as tech level rises. TL 10 or 11 versus TL 5 or 6 is like fighting natives with spears and stone axes.

 

[Condottiere]

We've moved on to smart bullets.

You need a combination of both, as the Air Force found out over South East Asia..

 

[kilemall]

I don't remember seeing those, but I did see some older DDs with twin 40mm Bofers on them. There were also some FRAM conversions. A small hanger that held a remote controlled flier that could drop 2 depth charges. Basically a frame with counter rotating props on top with the depth charges on the bottom. I think they used a tv screen to see the area near the remote flier. Basically an early drone.

That's DASH.

https://en.wikipedia.org/wiki/Gyrodyne_QH-50_DASH

 

[kilemall]

In terms of Traveller we're really looking at (loosely) a TL 5, 6, 7, 8 fire control problem and seeing the results.

At TL5 (pre WW 2) the AA gun is manually aimed. It might have an analog director that predicts the target's movement to improve accuracy. A 6 gun battery of heavy AA guns versus a period aircraft would need to fire about 400 to 600 rounds to shoot it down.

At TL 6 the gun is now director controlled with an electro-mechanical analog computer. Accuracy has improved to a point where 300 to 400 rounds would do the job.
Towards the end of this period, you get stuff like the US M2 90mm with SCR 584 radar and fire control system with VT fuzes. Now 4 guns with 200 to 300 rounds will take down an airplane.

At TL 7 adding increased rates of fire with automatic loading and better VT fuzes takes it to 150 to 200 rounds per gun.

At TL 8 a fully electronic computer with better radar and a fully automatic gun make it possible for 1 or 2 guns to destroy the target in less than 100 rounds, often less than 50.

Again, in terms of Traveller, you should see the same sort of exponential increase in effectiveness of most weapons as tech level rises. TL 10 or 11 versus TL 5 or 6 is like fighting natives with spears and stone axes.

My objection to most Traveller rulesets RE: TL is that you get to TL10 vs. TL15 and it's evolutionary not revolutionary. TL3 vs. TL6 is a yawning chasm comparatively speaking.

HG has it effectively +2 to hit per TL difference (+1 best computer, +1 weapon), and just +1 plus more spinal damage if the electronics are even. It's significant, but not exponential.

 

[kilemall]

We've moved on to smart bullets.

You need a combination of both, as the Air Force found out over South East Asia..

We had smarter bullets with the VT fuzes in WWII.

Without those the kamikazes would have been much more devastating- and artillery was far more effective.

https://en.wikipedia.org/wiki/Proximity_fuze#World_War_II

 

[JimMarn]

In 1970 we had an anti-ship/anti-aircraft Terrier missle launcher aboard ship. No AA guns. While we had a pair of 3-tube torpedo launchers, for anti-sub use we had the ASROC. Interesting, I just looked up some old hull numbers, and the ship type I served on were not Destroyers with missle launchers, but Guided Missle Frigates.

Edit: And another site calls them Guided Missle Destroyers.

The Charles F. Adams class of ships.

 

[BlackBat242]

Yes, the CFAs were destroyers.

And their two 5"/54 Mk 42 mounts were dual-purpose mounts, which could be used in an anti-aircraft mode (85 degree max elevation vs 65 degrees for the Mk 45 mount used in later destroyer classes).

And they had Tartar missile systems, not Terrier (Tartar was also on some frigates). Tarter was the short-range missile intended to protect the launching ship and one or two more close to it, Terrier was the medium-range missile intended to protect the whole battle group, and Talos was the long-range missile intended to protect the whole task force.

In an integrated battle group/task force, they provided 3 concentric "rings of protection", one inside the other (with Sea Sparrow for individual ship last-ditch protection).


Tartar was replaced by Standard-MR (with the range of Terrier) fired from upgraded Tartar launchers, and Terrier & Talos were replaced by Standard-ER (with near Talos range) fired from modified Terrier launchers (and new launchers).

The biggest difference in the Standard missiles was that the ER had a booster section attached to the MR missile.