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acelanceloet
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 12:32 pm
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gearboxes are big, so normally the electric motors should be about the same size as the gearbox. if there is some growth space in the design, I am certain it would fit in the current engine rooms.
DDV-1 might have been a design where each gas turbine propelled one shaft, making the powerplant symmetrical. that might also be something worth of looking into.

I wonder if it is an good idea to loose an additional GTG. your ship will only reach 27-28 knots, so when all weapon systems are in action and you thus need the power of all 3 GTG, you will have to lower the speed to take the power of one GTG off the main turbines.

something else worth looking into is adding RACER back in.

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Yasutomi
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 1:31 pm
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acelanceloet wrote:
gearboxes are big, so normally the electric motors should be about the same size as the gearbox. if there is some growth space in the design, I am certain it would fit in the current engine rooms.
But wouldn't the gearbox space be required for the generators each turbine will be driving?
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I wonder if it is an good idea to loose an additional GTG. your ship will only reach 27-28 knots, so when all weapon systems are in action and you thus need the power of all 3 GTG, you will have to lower the speed to take the power of one GTG off the main turbines.
Mmmm...fair enough. I only really deleted the third GTG to try to simplify arrangements. How does the Zumwalt manage then, given that I've seen it's total capacity quoted as 78 MW?
Quote:
DDV-1 might have been a design where each gas turbine propelled one shaft, making the powerplant symmetrical. that might also be something worth of looking into.
I haven't managed to find anything more than a sketchy overview of the DDV; I've certainly seen nothing about the internal layout. I shall keep looking, however!
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something else worth looking into is adding RACER back in.
RACER was a good idea, but I seem to recall that they trouble implementing it? If that's the case...it probably wouldn't be suitable for a lower-budget vessel.


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heuhen
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 1:52 pm
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come over this one:
http://www.globalsecurity.org/military/ ... assive.gif


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RP1
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 2:01 pm
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Quote:
But wouldn't the gearbox space be required for the generators each turbine will be driving?
For a GT driven propeller, roughly speaking, the alternator and motor are each the same size as the gearbox, but the GTA can be placed on the centreline (as in T45) with the electromotor to one side.

For waterjets it can be a little different, as their higher RPM and lower torque produces a much smaller GB for the same power.

RP1

PS. Does anyone have the Japanese illustration Colombamike linked to in a location that *doesn't* open LiveJasmin popups on my work computer? :?

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heuhen
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 2:20 pm
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RP1 wrote:
Quote:
But wouldn't the gearbox space be required for the generators each turbine will be driving?
For a GT driven propeller, roughly speaking, the alternator and motor are each the same size as the gearbox, but the GTA can be placed on the centreline (as in T45) with the electromotor to one side.

For waterjets it can be a little different, as their higher RPM and lower torque produces a much smaller GB for the same power.

RP1

PS. Does anyone have the Japanese illustration Colombamike linked to in a location that *doesn't* open LiveJasmin popups on my work computer? :?
Google chrome and adblock is fun..

https://dl.dropboxusercontent.com/u/887 ... _228lo.jpg


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Yasutomi
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 2:48 pm
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RP1 wrote:
For a GT driven propeller, roughly speaking, the alternator and motor are each the same size as the gearbox
This is the electric motor I'm proposing:

http://i0.wp.com/www.defensemedianetwor ... 2/04/1.jpg

I'm really hopeless at judging scale, but it doesn't seem impractically huge.

[ img ]

This arrangement should work. The forward engine room has the GTs, each driving an alternator in place of the regular Burke's gearbox. Since the complete GTG assemblies are only marginally longer than the main GTs (and require less ducting), the aft engine room should have ample room for the port motor and a fourth GTG. The starboard motor can fit in somewhere around/behind the midships GTG (there would have to be space for the prop shaft in this area in any case).

I can't see why that wouldn't work...and it shouldn't need much internal readjustment.

Would the extra weight of the forward main turbines on the starboard side cause stability problems, without the aft turbines to balance them out? I notice the Burke's aft superstructure extends further on the port side, so presumably that would help to counteract any trim issues...but I'm really no expert on such matters!


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acelanceloet
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 3:05 pm
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well, we have a converteam electrical motor on the parts sheet
[ img ]
the superstructure aft on the burke that is assymetrical houses the gas turbine air intakes ;) it would be gone when you remove that set of engines.
gas turbines are light, and I think with some juggling around it should be no problem having them on the centerline, or at least symmetrical, in the forward engine room. I think there would be no trim issues that could really be called issues.

I think this is really the ideal design for an IEP, 2 LM2500G4+ powered burke, which is ready for the near future.

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erik_t
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 3:47 pm
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How did we scale that part drawing, Ace? It looks a lot smaller in the photograph.


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acelanceloet
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 3:50 pm
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no idea, erik, it was drawn by shipright:
viewtopic.php?p=87352#p87352

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RP1
Post subject: Re: Small DDG Concept KitbashPosted: August 1st, 2014, 6:02 pm
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From the Electric Warship VI paper I have the Converteam (then Alstom) AIM as being 3.0m in length and 2.8m in external diameter. It's not clear if that is the length of the motor package including output shaft, however, and if the diameter is just the motor itself. I suspect it might, as the proportions are off for 2.8m to be the overall size.

RP1

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