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Navybrat85
Post subject: Aegis FrigatePosted: March 27th, 2017, 10:46 am
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Just stretching my drawing fingers here a bit. Inspiration taken from the F100 class, Americanized for US Navy use.

Obviously a work in progress, I know I need to add some more details like an anchor, and I think I will round that sharp corner at the intersection of the bow and keel.

[ img ]

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RegiaMarina1939
Post subject: Re: Aegis FrigatePosted: March 27th, 2017, 2:17 pm
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That's great and all but ships of this type don't normally use waterjets (which are mostly used on small craft and stealth ships) Otherwise, your mast is a little fragile-looking but this seems pretty good overall. Also, as you mentioned, that sharp curve in the bow needs to be rectified. She won't be very seaworthy with that kind of bow shape.

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Navybrat85
Post subject: Re: Aegis FrigatePosted: March 27th, 2017, 2:57 pm
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Normal screws or azipod then would be better?

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Blackbuck
Post subject: Re: Aegis FrigatePosted: March 27th, 2017, 5:15 pm
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There's no obvious reason not to stick with a conventional shafted layout. Fixipods or azipods could also work if required.

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acelanceloet
Post subject: Re: Aegis FrigatePosted: March 27th, 2017, 5:28 pm
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RegiaMarina1939 wrote: *
That's great and all but ships of this type don't normally use waterjets (which are mostly used on small craft and stealth ships) Otherwise, your mast is a little fragile-looking but this seems pretty good overall. Also, as you mentioned, that sharp curve in the bow needs to be rectified. She won't be very seaworthy with that kind of bow shape.
Waterjets have nothing to do with stealth (their big steering exhausts on the waterline are ever quite bad for it :P) but have a lot do with speed. Waterjets are inefficient in reverse, more vulnerable (due to the steering exhausts with an reverser on it) and inefficient at low speeds. However, they have a lot less trouble with cavitation, are very efficient at high speeds and do not stick out under the hull.

so, depending on the role of your vessel, waterjets might work or not work. there is also the AWJ-21 development that I myself think to be very promising. There are also some cases of frigates with both propellers and waterjets, so when the propellers lose efficiency due to cavitation, the waterjet kicks in.

long story short, look at what your ship is supposed to do. Does it have to go very fast or quite fast most of the time (like LCS), then waterjets are the option. Regular propellers are the best when you go for the role most modern warships seem to be doing right now, unless you have to change direction a lot at low speeds, when azimuths work best. Things like the AWJ-21 and fixed pod drives fit somewhere in between that spectrum.

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RegiaMarina1939
Post subject: Re: Aegis FrigatePosted: March 27th, 2017, 7:45 pm
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acelanceloet wrote: *
RegiaMarina1939 wrote: *
That's great and all but ships of this type don't normally use waterjets (which are mostly used on small craft and stealth ships) Otherwise, your mast is a little fragile-looking but this seems pretty good overall. Also, as you mentioned, that sharp curve in the bow needs to be rectified. She won't be very seaworthy with that kind of bow shape.
Waterjets have nothing to do with stealth (their big steering exhausts on the waterline are ever quite bad for it :P) but have a lot do with speed. Waterjets are inefficient in reverse, more vulnerable (due to the steering exhausts with an reverser on it) and inefficient at low speeds. However, they have a lot less trouble with cavitation, are very efficient at high speeds and do not stick out under the hull.

so, depending on the role of your vessel, waterjets might work or not work. there is also the AWJ-21 development that I myself think to be very promising. There are also some cases of frigates with both propellers and waterjets, so when the propellers lose efficiency due to cavitation, the waterjet kicks in.

long story short, look at what your ship is supposed to do. Does it have to go very fast or quite fast most of the time (like LCS), then waterjets are the option. Regular propellers are the best when you go for the role most modern warships seem to be doing right now, unless you have to change direction a lot at low speeds, when azimuths work best. Things like the AWJ-21 and fixed pod drives fit somewhere in between that spectrum.
I'm just saying I wasn't sure whether or not waterjets were a good bet for such a big ship. Since they are normally used on smaller craft.

It says right here in your document that a traditional frigate hull such as the one depicted here would not be able to effectively accommodate a waterjet system and the associated equipment without changing the hull form:

"Frigate sized surface combatants are almost exclusively optimised for propellers and, therefore, the impact upon the hullform design criteria will need to be determined to accommodate the AWJ-21TM geometry effectively"

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Navybrat85
Post subject: Re: Aegis FrigatePosted: March 29th, 2017, 2:28 am
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[ img ]

Made a few changes. Topside, changed the upper superstructure and electronics. Changed the bow, curving the intersection of keel and bow, and sweeping the bow slightly forward (the original bow line looked a bit odd to me. *Shrug*) changed propulsion to shafts and screws, with rudder. I played around a bit with sonar but left it the way it was.

Added a single SH-60 on the flight deck. I added a generator exhaust above the hangar, and a 25mm Remote Weapon Station.

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RegiaMarina1939
Post subject: Re: Aegis FrigatePosted: March 29th, 2017, 10:54 am
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I think it looks much better than it did, and more seaworthy and practical. Good work.

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Navybrat85
Post subject: Re: Aegis FrigatePosted: March 29th, 2017, 11:22 am
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Thank you!

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Hexelarity
Post subject: Re: Aegis FrigatePosted: March 29th, 2017, 6:07 pm
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Honestly i thought the Water jet was fine, there are some large ships that use the water jet, honestly, there is no problem with a large or medium sized ship using waterjets. But then again its your art and you can do what you want :)

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