Trubble at Matelot Mill (VFD drive issues?)

[Geoff TheasbyParticipant @geofftheasby]

Yes, Neil. Also the surface, at least on aircraft, is covered with radar-absorbent paint, or other material. This goes back to WWII when U-boats were covered in 'Stumpf', for the same purpose. There are also no straight edges, like round the cockpit cover, it being broken up in a zig-zag fashion to reflect radar signals in all directions. The Zumwalt's (and Type 45) superstructure is angled off the vertical, so reflections go skyward. The engine exhausts are also dispersed to hinder heat-seeking missiles, like the Stealth bomber, and even in tanks. This is in addition to towed or free decoys, flares, etc.

Geoff

[John CoatesParticipant @johncoates48577]

Posted by Ady1 on 30/01/2016 11:04:57:

Unknown to NATO, Yugoslav air defenses operators had found they could detect F-117s with their obsolete Soviet radars after some modifications.

**LINK**

Thanks Ady I really enjoyed reading that. Brightened my lunch break

[MWParticipant @mw27036]

Posted by Neil Wyatt on 25/11/2016 09:01:22:

The 'stealth' motor needs a new rubber band.

 

Might by interesting to explain why these 'stealth' machines always have lots of flat surfaces. Imagine light or radar hitting a typical convex surface – the light is reflected away at all angles, with a flat surface it all bounces off in one direction so the foe has to be exactly aligned with the surface. Clearly other ships will never align with the stealth ship's angled surfaces and a plane or missile would have to fly directly towards the ship at exactly the right angle to get a steady signal.

It isn't unusual to see reflections of the sun on car windscreens from many miles away, yet imagine how hard it would be to use a mirror to exactly illuminate a spot at such a distance.

Neil

Edited By Neil Wyatt on 25/11/2016 09:06:51

It couldn't be that they just wanted it to look a little space age?

I'd be a little annoyed if all that money made it look like an ugly tugboat regardless of wether or not it was good for radar.  

I suppose like anything, it would have to impress the owners as well as deter an enemy. 

Michael W

Edited By Michael Walters on 25/11/2016 14:51:03

[Neil WyattModerator @neilwyatt]

Posted by mechman48 on 30/01/2016 12:43:19:

Posted by Sam Longley 1 on 30/01/2016 10:38:44:

Posted by Clive Hartland on 30/01/2016 09:16:22:

I understand that they have 2 ring mains on a warship. Also separate generating stations for other purposes.

One would have thought so, but on the BBC programme it indicated the section of the ship where both generators are fitted suggesting that they are side by side

I believe the Russians have now got a DVD of it

Knowing our lot, the backup is probably an Ipad- at least they work!!!

Edited By Sam Longley 1 on 30/01/2016 10:40:02

It amazes me that in the interest of 'National Security' we openly disclose / broadcast all our technology globally via the BBC news… probs with our ships… our drone statistics etc. … army / troop size dispositions etc. who needs spies, our 'enemies' only have to sit & watch the BBC news to get all & any information they need … it seems that our National Security system, & the BBC, seem more than a bit lax, or very naïve when it comes to keeping their mouths shut, the old WW2 adage 'Walls have ears' is no longer apt… just been replaced by 'watch the BBC news … get all you need' … obviously approved & sanctioned by the MOD!

George.

Do you rally think the Beeb get the whole story or just what the MOD want people to know?

Neil

[Sam Longley 1Participant @samlongley1]

Posted by Neil Wyatt on 25/11/2016 09:01:22:

The 'stealth' motor needs a new rubber band.

Might by interesting to explain why these 'stealth' machines always have lots of flat surfaces. Imagine light or radar hitting a typical convex surface – the light is reflected away at all angles, with a flat surface it all bounces off in one direction so the foe has to be exactly aligned with the surface. Clearly other ships will never align with the stealth ship's angled surfaces and a plane or missile would have to fly directly towards the ship at exactly the right angle to get a steady signal.

It isn't unusual to see reflections of the sun on car windscreens from many miles away, yet imagine how hard it would be to use a mirror to exactly illuminate a spot at such a distance.

Neil

Edited By Neil Wyatt on 25/11/2016 09:06:51

if that was the case ( Curved surfaces etc etc) why is it that the radar reflector on my boat is made from flat surfaces which are inclined at 45 degrees from the horizontal or vertical ( thus directing the reflection away from the transmitter one would have thought)& not simply a circular ball that would always display a section of its surface directly at the transmitting radar?

& if it is that hard to direct a mirror why did Colonel Custer & co use them to signal to the rest of the cavalry in all the westerns ( up to the bit where he got an arrow through his hat that is !!) & why have I got one as a signalling mirror as standard equipment in my liferaft.

[KWILParticipant @kwil]

The left leaning BBC will always publish anything that helps the "other side"

[Swarf, Mostly!Participant @swarfmostly]

Sam,

If your radar reflector is the usual form it is what is known as a 'triplane target'. It is a geometrical fact that three mutually perpendicular plane surfaces reflect an incoming 'ray' from plane to plane in such a way that it returns in a direction parallel to that from which it arrived. So it gives a very strong echo back to each illuminating source.

Best regards,

Swarf, Mostly!

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Swarf, Mostly! on 25/11/2016 16:28:23:

Sam,

If your radar reflector is the usual form it is what is known as a 'triplane target'. …

.

Also known as a retro-reflector … found in bicycle reflectors, and on the Moon.

MichaelG.

.

https://en.m.wikipedia.org/wiki/List_of_retroreflectors_on_the_Moon

Edited By Michael Gilligan on 25/11/2016 17:05:22

[SillyOldDufferModerator @sillyoldduffer]

Posted by Sam Longley 1 on 25/11/2016 16:18:25:

Posted by Neil Wyatt on 25/11/2016 09:01:22:

…

…

& if it is that hard to direct a mirror why did Colonel Custer & co use them to signal to the rest of the cavalry in all the westerns ( up to the bit where he got an arrow through his hat that is !!) & why have I got one as a signalling mirror as standard equipment in my liferaft.

Hollywood.

I'm sure an expert will correct me if I'm wrong but I think the US Army at that time used a semaphore system called 'wig wag' rather than mirrors.

Sunny conditions in India, and later South Africa, favoured Heliographs in British service. Surplus Heliographs are fairly common because military map makers used them as theodolite targets until microwave and aerial surveying took over. I don't think they were used much for signalling in morse.

All a life-raft mirror has to do is attract attention. It would be quite hard to hit one with an anti-ship missile, though it might be fun to try!

Dave

[MWParticipant @mw27036]

Yeah.
Im thinking that the shape also makes the ship a hard target for guns and missles. Big problem being without a conventional war recent in history it makes it harder to design a hull for ship to ship combat.(not that peace is a bad thing though!)

Edited By Michael Walters on 25/11/2016 17:57:10

[Neil WyattModerator @neilwyatt]

Posted by Sam Longley 1 on 25/11/2016 16:18:25:

Posted by Neil Wyatt on 25/11/2016 09:01:22:

The 'stealth' motor needs a new rubber band.

Might by interesting to explain why these 'stealth' machines always have lots of flat surfaces. Imagine light or radar hitting a typical convex surface – the light is reflected away at all angles, with a flat surface it all bounces off in one direction so the foe has to be exactly aligned with the surface. Clearly other ships will never align with the stealth ship's angled surfaces and a plane or missile would have to fly directly towards the ship at exactly the right angle to get a steady signal.

It isn't unusual to see reflections of the sun on car windscreens from many miles away, yet imagine how hard it would be to use a mirror to exactly illuminate a spot at such a distance.

Neil

Edited By Neil Wyatt on 25/11/2016 09:06:51

if that was the case ( Curved surfaces etc etc) why is it that the radar reflector on my boat is made from flat surfaces which are inclined at 45 degrees from the horizontal or vertical ( thus directing the reflection away from the transmitter one would have thought)& not simply a circular ball that would always display a section of its surface directly at the transmitting radar?

& if it is that hard to direct a mirror why did Colonel Custer & co use them to signal to the rest of the cavalry in all the westerns ( up to the bit where he got an arrow through his hat that is !!) & why have I got one as a signalling mirror as standard equipment in my liferaft.

Because three plane surfaces at exactly 90-degrees create a shape that will reflect an incident beam back out the way it came; the same effect is used in various types of reflectors including the ones left behind by apollo missions as laser targets. They fit small reflectors like this to stealth aircraft when being used in civilian airspace (and its why the avoid 90-degree corners at all costs on stealth machines).

The sun's angular diameter seen from earth is 0.5 degrees, so the beam from a signalling mirror spreads at this angle. At a mile the beam becomes about fifteen yards across. A small spot to hit a target by chance, but possible to hit with a bit of skill. Proper heliographs used for signalling (where actual messages not just random flashes are needed) were equipped with sights for accurate setting up.

Little extra info I found when reading up on the F117 earlier – it was all flat plates because 1970s computers couldn't do the hard maths to design a stealth plane with curved surfaces.

Neil

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