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-   -   [REQ] Separated Port & Starboard Engine Control (https://www.subsim.com/radioroom/showthread.php?t=119652)

Ducimus 08-02-07 05:43 PM

Quote:

I don't want an American Das Boot.
What? you don't want a blockbuster movie that sensationalizes fleet boats, the pacific theater, and the tradgety of war that will draw fans from all corners of the globe who will pour praise upon praise on pacifc submarines without any regard for nationaity or historical politics of the time for generations to come? Whats wrong with you!? :rotfl:

(sarchasm)

Fearless 08-02-07 08:47 PM

Quote:

Originally Posted by Reaves
Quote:

Originally Posted by Fearless
Quote:

Originally Posted by Ducimus
I want a das boot style movie set in the pacific :lol: (and no, Run silent run deep doesnt count.)

Yes, totally with you on this one Ducimus :smug:

I think you SECOND his idea.

Perhaps you're DOUBLY in agreement.

I can't think of anymore double post related puns. :p:up:

I'll DOUBLE that in a SECOND but then again I really DOUBT it. :lol:

Nuc 08-09-07 04:11 PM

Quote:

Originally Posted by Sailor Steve
In fact, I want a new version of the old TV series The Silent Service.

Actually, I wouldn't mind seeing the original again. It's only been 50 years.:dead:

VHS tapes of Silent Service episodes are available here:

http://www.usssealion.com/sealion/Si...vice_Tapes.htm

Sailor Steve 08-09-07 06:06 PM

THANKS NUC!!!:rock:

I'd kiss you, but I wouldn't want you to get the wrong idea.:rotfl:

DirtyHarry3033 08-09-07 06:53 PM

Quote:

Originally Posted by Payoff
Oh, by the way, U-571 makes a pretty good coaster while watching Das Boot. :lol:

Agreed! If I had U-571 I would be setting my beer on it when I watch Das Boot. Fortunately I saw it on cable before buying it, and so I didn't ;) (Buy it that is...)

Mcaa666, welcome! If you've got time on your hands, rent (or better yet buy) a copy of Das Boot - The Original Uncut Version. Nearly 5 hours (293 minutes to be exact) that will bring you closer to the experience of serving on a U-boat than anything short of actually being there. Everything from mind-numbing boredom to sheer terror and everything in between.

I've watched it 3 times in the year I've had it and every time, it's been time well spent...

DH

Fearless 08-09-07 07:01 PM

Yep, I have the 5 hrs or so version of Das Boot myself which includes photographs etc of the crew as part of the package.

Mav87th 08-11-07 10:54 AM

Go in and vote here so we can have a DVD set of the TV series...

http://www.imdb.com/title/tt0050061/

Come on all of you - lets make a new riot :arrgh!:

mcaa666 08-11-07 11:30 AM

Hi guys thnx for the warm welcome and all, nice to see this turned into a movie review thread (LOL).
And seriously i think when someone plays SH3 and SH4 they are obligated to know their sub movies / series.
I know that U-571 isn't the best sub movie out there (except when it comes to the sound effects maybe) but hey in my defence i would like to state that i practicly watch Das Boot Uncut version almost once every two months ( after all it is the best one and my all time favorite movie).
I was just watching it in terms of research because i thought i noticed them using only one engine and guess what they did; hence the name of this thread.
As for Silent Service i just recently copied it from a mate of mine and i am watching it now.

Much regards to all you fine modders out there and too bad that the separated engine controls are not possible.

Note: The message above is not intented to be as serious as it might look, so please forgive me.

jdkbph 08-12-07 10:11 AM

Yes, "Das Boot - Original Uncut" is absolutely the one to watch...

But to address your original question... reversing one propeller is probably not necessary and nothing you would ever use in this game.

The idea that you will turn faster by reversing the inside prop is a misconception... at least with things like submarines and destroyers or any ship with a high "fineness" (ie, length to beam) ratio. The propellers are just too close together for this to be efficient. With any kind of way on, the max turn rate you might achieve by doing this would be very low compared to a rudder only turn, and would require an inordinate amount of thrust (not something you'd want to do while running silent for instance).

To explain why this is so...

A ship turns because flowing water deflects off the rudder, creating a force vector away from the direction the rudder is turned. This pushes the back end of the ship in the opposite direction. The thrust of the propellers, being aligned with the axial centerline of the ship, starts driving it away from the original path and... it turns.

Reversing the propeller on the inside of the turn would actually be counter-productive, as the low pressure zone created behind the propeller would reduce the amount of force being applied by the flowing water to the rudder. Sort of like an airplane wing or control surface in a stalled condition, it would loose efficiency.

The only reason you might want to use the submarine's screws to assist with a turn would be if you needed to push the bow away from something without pushing the stern in the opposite direction... such as when you are alongside a pier. By reversing the propeller on the side opposite the dock while going ahead with the other propeller, you could slowly turn the ship, moving the bow away from the dock with the pivot point at or near the stern.


JD

DirtyHarry3033 08-12-07 02:41 PM

JD, thanks that was a great post! I never really thought about those things before but it makes perfect sense now that you've pointed it out. And you explained it well enough that even a moron like me can understand :yep:

I suppose it also explains why the Titanic hit the iceberg and sank. When 1st Officer Murdoch ordered "Hard a-starboard" (which was correct) and "all engines back full" (which was wrong) he basically destroyed Titanic's ability to turn by removing most of the force of the water against the rudder.

If he'd ordered "all ahead full" instead, I imagine Titanic would have had a long and illustrious career, 1,496 people would have lived instead of dying, and Kate Winslet, Leo DiCaprio and James Cameron would be somewhat poorer today ;)

At any rate, I can see one instance where it would be good to have seperate control over the props - if your rudder was destroyed. It would give you at least some directional control.

Example being UA Flight 232, a DC-10 that crashed in Sioux City Iowa in 1989 after losing one of three engines and all hydraulic systems. The pilots were able to control both course and altitude thru throttle control only - increase thrust to climb, decrease to descend, and apply differential throttle to turn left or right. Even though the plane crashed, there were 185 survivors, which is pretty amazing. Proof that differential engine control can be useful in certain situations!

DH

jdkbph 08-12-07 06:17 PM

Quote:

Originally Posted by DirtyHarry3033
I suppose it also explains why the Titanic hit the iceberg and sank. When 1st Officer Murdoch ordered "Hard a-starboard" (which was correct) and "all engines back full" (which was wrong) he basically destroyed Titanic's ability to turn by removing most of the force of the water against the rudder.

If he'd ordered "all ahead full" instead, I imagine Titanic would have had a long and illustrious career, 1,496 people would have lived instead of dying, and Kate Winslet, Leo DiCaprio and James Cameron would be somewhat poorer today ;)

A point that's been debated for years and years :)

I think the current consensus is that while, yes, in theory ahead full would have been the better choice, with less than a minute between the 'berg sighting and the collision, no engine orders given after the sighting would have had the least effect on the outcome.

Another interesting, if sometimes confusing, aspect here is the starboard helm order. At that time, starboard helm referred to the act of pushing the "tiller" to starboard, which actually causes the ship to turn to port. :o


Quote:

Originally Posted by DirtyHarry3033
At any rate, I can see one instance where it would be good to have seperate control over the props - if your rudder was destroyed. It would give you at least some directional control.

Absolutely, yes. I wasn't thinking about damage.

JD

DirtyHarry3033 08-12-07 06:48 PM

Quote:

Originally Posted by jdkbph
A point that's been debated for years and years :)

I think the current consensus is that while, yes, in theory ahead full would have been the better choice, with less than a minute between the 'berg sighting and the collision, no engine orders given after the sighting would have had the least effect on the outcome.

Another interesting, if sometimes confusing, aspect here is the starboard helm order. At that time, starboard helm referred to the act of pushing the "tiller" to starboard, which actually causes the ship to turn to port. :oJD

Yep the rudder command is confusing today! But back in the day you had a tiller that you pushed right to go left, and left to go right. So counter-intuitive it's a wonder you didn't have collisions every day...

The best choice Murdoch could have made (based on 20/20 hindsight) was, seeing he had no chance to miss the berg, to order a course right for it, followed by full astern. The bow would be totally destroyed, but only 1 or 2 compartments would be opened to the sea and Titanic and her passengers would have survived.

Consider Stockholm, who collided head-on with and sank Andrea Doria in 1956 - she lost what, 30 or 40 feet of her bow anyway, and not only didn't sink but was 1st to engage in rescue of Doria's passengers and crew, and then took them to NYC under her own power, was repaired and sold to another line and afaik is still sailing today...

I better shut up now, I'm totally OT!!!!

DH


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