DEMON

[sfhand]

I hope this question hasn't already been asked and answered. After reading the manual regarding determining platforms using DEMON I'm under the impression a contact with a 5 bladed prop should have 6 lines in the 688i demon waterfall. Is this correct? Is the number of lines present determined by signal strength? I'm using 1.03b and LWAMI 3 and I have a contact that I think is a typhoon but the demon info doesn't give me the proper amount of blades and I think it even gained a line after some time (I may have miscounted originally though). I've looked for other contacts with 1000 as their 4th frequency but I don't think any of them are in the campaign scenario (protect the rebel delta and typhoon - I've been stuck on this mission for a long time).

[TLAM Strike]

Submarines and surface ships have devices to confuse systems that count the blades (sometimes called 'blade reduction' or 'blade rate suppresson'), on subs you will see them gain lines as they close- a skilled operator in DW can even tell you its a sub just by seeing this compaired to the range of a contact.

A sub with Five blades will have Five lines visable on DEMON, the shaft line will also be the same line as the 1st blade line.

[compressioncut]

Originally Posted by TLAM Strike

A sub with Five blades will have Five lines visable on DEMON, the shaft line will also be the same line as the 1st blade line.

Slight clarification - the fifth line will be the first blade harmonic overlaid with the fifth shaft harmonic.

That's how it works in real life, too, and is the biggest part of narrowband passive acoustics in DW that is true-to-life (albeit best case scenario, all the time).

[MaHuJa]

Originally Posted by TLAM Strike

Submarines and surface ships have devices to confuse systems that count the blades (sometimes called 'blade reduction' or 'blade rate suppresson'), on subs you will see them gain lines as they close- a skilled operator in DW can even tell you its a sub just by seeing this compaired to the range of a contact.

So it's not just plain old signal loss at fault here?

[sfhand]

Originally Posted by compressioncut

Slight clarification - the fifth line will be the first blade harmonic overlaid with the fifth shaft harmonic.

That's how it works in real life, too, and is the biggest part of narrowband passive acoustics in DW that is true-to-life (albeit best case scenario, all the time).

This is really confusing me. The manual says (for each platform with DEMON) "The first line on the left indicates the shaft rotation speed. The other lines indicate individual blades on the propeller."

As I understand TLAM strike the shaft rotation speed is modeled on a line that also represents a blade line which, by my reading, contradicts the manual. Perhaps I've missed an update in a readme doc or something. I will post my question on the SCS board to get their take on the issue.

[LuftWolf]

That's talking about harmonics, meaning that their will be some base tone for the shaft and then also some other resonate frequency visable on the demon.

In order to use the DEMON to find target speed, assuming you have classified it, you just need to input the TPK and line the cursor up with the leftmost 1/4 of the leftmost line and that will give you the speed.

In order to use the DEMON for target classification, the number of lines you can see is the number of blades on the target propeller(s). If you see the rightmost lines fading out, there might be a blade or two that you can't see yet so don't rely on the blade count.

[TLAM Strike]

Originally Posted by MaHuJa

So it's not just plain old signal loss at fault here?

Well the system or blade design exacerbates the signal loss.

[compressioncut]

Originally Posted by sfhand

This is really confusing me. The manual says (for each platform with DEMON) "The first line on the left indicates the shaft rotation speed. The other lines indicate individual blades on the propeller."

As I understand TLAM strike the shaft rotation speed is modeled on a line that also represents a blade line which, by my reading, contradicts the manual. Perhaps I've missed an update in a readme doc or something. I will post my question on the SCS board to get their take on the issue.

No, that's correct. The first line is the shaft rotation rate. Lines beyond the first one are harmonics of the shaft rotation rate. The final line is the first blade rate harmonic, which (in DW) is also the final shaft harmonic.

||||| is shaft 1, shaft 2, shaft 3, shaft 4, shaft5/blade1. For a five bladed contact. The theory is the same for any number of blades.

It works perfectly in DW, but in real life you are very unlikely to get something that cut-and-dried with a modern naval contact. Shaft lines are rare and usually a symptom of a mechanical problem with the ship/sub. Blade is more common but you may not get blade1, perhaps blade2 or 3 only. And so on.

[Kapitan]

the only surface ship that has more than 4 blades on its propellors is the cruise liner Queen Elizabeth 2 she has two seven bladed propellors 99% of ships now only have four or fave blades, most submarines 7

[compressioncut]

Originally Posted by Kapitain

the only surface ship that has more than 4 blades on its propellors is the cruise liner Queen Elizabeth 2 she has two seven bladed propellors 99% of ships now only have four or fave blades, most submarines 7

Umm no.

[Three14]

Wow...the simplest of questions has become incredibly esoteric!
Interesting answers.

However, in DW I also understood that, under perfect conditions a 4 bladed prop will show as 5 lines in DEMON (in the game). The first line is the shaft. This is different from what is stated in the second post (4 bladed prop will show 4 lines -- the first line is both the shaft AND the first blade). I remember this being true in earlier games, but it's been a long while since I checked.

However, it WAS true that fainter(?) contacts were more likely to display fewer prop lines in DEMON. So, a sub in which you expected to see 7 lines might first appear as 3 or 4 lines until it closed.

Things may be different, but I believe this is the question being posed about DW in original post.

[Kapitan]

container ships and oiltankers with single screw arrangement have one five bladed veriable pitch propellor (depending on age) just realise what i put 99% no i ment 90% because its true there is realy very very few ships with more than 5 blades now days

[goldorak]

Originally Posted by Three14

Wow...the simplest of questions has become incredibly esoteric!
Interesting answers.

However, in DW I also understood that, under perfect conditions a 4 bladed prop will show as 5 lines in DEMON (in the game). The first line is the shaft. This is different from what is stated in the second post (4 bladed prop will show 4 lines -- the first line is both the shaft AND the first blade). I remember this being true in earlier games, but it's been a long while since I checked.

However, it WAS true that fainter(?) contacts were more likely to display fewer prop lines in DEMON. So, a sub in which you expected to see 7 lines might first appear as 3 or 4 lines until it closed.

Things may be different, but I believe this is the question being posed about DW in original post.

No actually in DW there is a discrepancy between what the manual says and what you observe on the demon station.
For instance for a n bladed contact according to the manual you should have n+1 lines in the demon station (first one for the shaft, and the other n lines for the blades) whereas in game you observe only n lines in total.

[Wim Libaers]

And some DEMON data here indicates it's even more complicated:
http://www.fuzzytech.com/e/e_a_kumm.html

[goldorak]

Originally Posted by Wim Libaers

And some DEMON data here indicates it's even more complicated:
http://www.fuzzytech.com/e/e_a_kumm.html

Wow, that reading gave me a headache
In any case the orginal question of sfhand wasn't on the theory of demon but the discrepancy between what is specified in the manual and what is observed INGAME.
So yes S.C.S should correct the manual because it creates confusion for the newbies (i fell into this trap months ago ).