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GRISHA-II
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 1st, 2016, 2:19 pm
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nice ships


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heuhen
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 1st, 2016, 4:07 pm
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Lifting fans, are they powered by the engine in the engine room, thus long shaft. Or do you have engine next to the lifting fans.

Having long shaft isn't so good. For example on the Norwegians vessels, both corvettes and the mine hunter vessel, they have separate engine for propulsion, and either electric or direct drive on the lifting fans (depending on build year), most of them have the engine placed next too the lifting fans.


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citizen lambda
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 1st, 2016, 5:31 pm
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Thanks everyone for the feedback!
Hood wrote:
The deck plans are great, too, I think the first I've seen on SB and certainly very well drawn and clear despite the small scale.
I don't recall seing exactly the same thing, particularly using the top view as basis, but the principle is heavily inspired by Erik_t's work on his fusion destroyer, which is at a level I can only feebly strive for.
heuhen wrote:
Lifting fans, are they powered by the engine in the engine room, thus long shaft. Or do you have engine next to the lifting fans.

Having long shaft isn't so good. For example on the Norwegians vessels, both corvettes and the mine hunter vessel, they have separate engine for propulsion, and either electric or direct drive on the lifting fans (depending on build year), most of them have the engine placed next too the lifting fans.
So far they are driven directly from the boost turbines through the long driveshafts visible in dark grey on the main deck plan.
I see your point, it is probably a mechanical liability to have these huge shafts crossing the boat, as well as keeping the boost turbine running at 20% power or something at nearly all speeds just to stay afloat. TBH this is directly taken from what little I know about the power plant of the Pr.1239, where the main power plant feeds the lift fans along with the propellers. Probably exceedingly conservative on my part, since I have about 20 years development time to move away from that clunker. Inspiration from foreign designs (say, the Skjold) in the meantime is a perfectly reasonable assumption. There sould be some room to add engines in the forepeak or somewhere closer to the fans, since the backup generators are already there. I'd worry about the added weight forward, but the fans themselves should take care of that. Thinking about it some more, I don't see why I haven't moved to a fully electric drive for such a modern design, which would save no end of weight and space compared to the shafts (and gearboxes!). There should be enough space saved for batteries, gearboxes and alternators forward of the main turbines for a decent high-power switching array, and that way I can route the feeds outwards through the sponsons to 1) improve ergonomics in the living spaces and 2) avoid routing high-amp leads around the gun turret basket and ammo stowage...
OTOH, the direct drive from the turbines looks like one of those baffling idiosyncrasies typical of Soviet design... Wouldn't want to make all this too well thought-out, would we?

Ah well. You make a good point either way, so I'll give it a think and post an updated deck plan depending on what I settle on.

Edited for typos

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Last edited by citizen lambda on December 4th, 2016, 2:57 pm, edited 1 time in total.

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heuhen
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 2nd, 2016, 12:28 pm
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skjold class was designed with a Diesel and gas turbine combo... but for some reason the gearbox, could handle both engine at the same time.... so they replaced the cruise diesel with an additional turbine.


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sebu
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 2nd, 2016, 4:47 pm
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Great job indeed! Great looking vessels with thought-out sections/top view. A milestone in SB; I think :)


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citizen lambda
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 4th, 2016, 2:55 pm
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Following Heuhen's comments above on the transmission layout of the hover systems of Pr.2238 - and the ensuing epiphany on the sheer retardedness of my original full-shaft configuration, I have touched up the deck plans to:
- Remove the fan driveshafts from the main deck and their gearboxes
- Move the machinery control stations and batteries to make space to
- Insert new alternators between the boost turbines, control stations and air intakes
- Touch up the layout of the living spaces
- Rearrange the turret well deck to improve accessibility, removed one extra ammo basket
- Remove one control workstation, added one workbench for small repairs
- Turn the drive boxes of the fans to electrical engines and move them for better accessibility
- Add gearboxes to the diesel generators and shafts to the front fans as emergency backup power
- Move the generators and generally re-arrange the attending space in the forepeak

The electrical feeds between the main alternators and the fans don't show up on the plan. The composite construction should allow them to be embedded close to the deck structure to take as little space as possible. The battery volume is utterly tentative and probably not representative of the capacity needed. Same goes for the fuel tankage, now that I think of it.

[ img ]

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erik_t
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 4th, 2016, 11:48 pm
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That's a hell of an illustration. A+.


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Hood
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 5th, 2016, 8:32 am
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Methinks you might need more fuel, I'm sure those gas turbines are going to be thirsty beasts.

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odysseus1980
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 5th, 2016, 11:47 am
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Previous comments cover me also, but I noticed a typo in Pr.404.1 B-side: It says displacement "2075t", when in text above says "275-ton..."

Top view is incredible, gives an idea how this ship works.


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citizen lambda
Post subject: Re: Soviet Century/Cold War 2020 AUPosted: December 5th, 2016, 3:53 pm
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Hood wrote:
Methinks you might need more fuel, I'm sure those gas turbines are going to be thirsty beasts.
Fair point, but please consider that the plan views don't include the bilge keel volume. The underwater part of the sponsons thins down, so there must remain some space between the lowest deck and the keel to serve, among other things, as fuel storage.
Now tell me if you think that this assumption looks unrealistic, or that I would have to change something (e.g. draft) to make it work.
This being said, I can't guarantee that that volume would be enough for the stated cruise range; I haven't really pushed the modelization that far, and hover-catamaran energy calculations are a beast because of the range of different travel modes.
odysseus1980 wrote:
Previous comments cover me also, but I noticed a typo in Pr.404.1 B-side: It says displacement "2075t", when in text above says "275-ton..."
Well spotted, probably a copy-paste mistake. Corrected in the original.

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