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Bubblehead Nuke · 03-01-09, 02:50 PM

I know, I know. Here comes BN with another post.

Let me address some of the comments in parts here:

One:
Planes in the sail, which we called 'fairwater' planes are closer to the ships center of bouyancy and mass, Thus they exert a more up/down force rather than a rotational force. The bow planes are farther away from the center of rotation and thus move the whole bow up or down. It is easier to maintain depth with fairwater planes as you have less hull rotation with control surface movement.

With that being said, bow planes are more useful in a stern plane casualty situation as they CAN provide a counterforce. With fairwater planes a jam dive situation is BAD as there is not enough control authority (do to the LACK of hull rotation) to use the fairwater planes to bring the angle off the boat.

This is the primary reason they went BACK to bow planes as you have increased control authority in a casualty situation.

Any boat in shallow depth is going to be prone to broaching. The surface area of the hull is FAR greater than the fore/aft plane area and that is the main source of the 'suction' that pulls you to the surface.

Two:
You have the same number of penetrations for bow planes. No, strike that, you have MORE with bow planes as you now have a retraction mechanism that must have a seperate hydraulic source. They are both hydraulically operated. If they are in the sail or bow, they still have to be powered by something.

A 688 could have had the ability to rotate the fairwater planes to the vertical for ice ops. It would have required a slight enlargement of the sail but they decided against it for the following reasons:

1) this boat was supposed to be a fleet support boat. Thus under ice ops were not a design consideration.
2) Speed was the PRIMARY factor. A larger ice hardened sail would have increased the wetted hull area and mass and thus affected the the primary design consideration of speed.
3) a 688 class has a SEVERE handling problem due to sail position and size already. Adding a larger sail would have lowered the critical speed at which these problems exhibited themselves.

Again, sail size and wetted area are large considerations in speed and controlability. The sail is large enough to hold the sensors, masts, and then some. The access to the top of the sail takes up more space than you can imagine and it a large factor in sail design. Thus control authority and operational considerations drive the move back to bow planes in the newer boats.

Three:
About noise considerations. They are retractable for surface through ice operations and for harbour damage considerations. NO submarinier is going to rig in a control surface while underwater. If you have a causalty you are going to WANT those bow planes to help you get to the surface. You are not going to be wanting to wait for them to rig out and possible FAIL when you need them most. They are going to be rigged out once out of the harbor and LEFT that way until you HAVE to rig them back in.

Bubbleheads are about having a main system with a backup system with an emergency system for when everything goes to hell. Rigging in the bow planes gets rid of the main and the backup system. NOBODY is going to trust there butt with just the emergency system. If you are down to relying on that then you in DEEP doo-doo already.

Also, noise from the water flowing over the bow planes is going to be neglible. If you are going fast enough for it to be an issue on the bow array, you are going to be having enough flow noise over the dome that it will not be an issue anyway.

03-01-09, 02:50 PM	#6
Bubblehead Nuke XO Join Date: Feb 2006 Posts: 435 Downloads: 5 Uploads: 0	I know, I know. Here comes BN with another post. Let me address some of the comments in parts here: One: Planes in the sail, which we called 'fairwater' planes are closer to the ships center of bouyancy and mass, Thus they exert a more up/down force rather than a rotational force. The bow planes are farther away from the center of rotation and thus move the whole bow up or down. It is easier to maintain depth with fairwater planes as you have less hull rotation with control surface movement. With that being said, bow planes are more useful in a stern plane casualty situation as they CAN provide a counterforce. With fairwater planes a jam dive situation is BAD as there is not enough control authority (do to the LACK of hull rotation) to use the fairwater planes to bring the angle off the boat. This is the primary reason they went BACK to bow planes as you have increased control authority in a casualty situation. Any boat in shallow depth is going to be prone to broaching. The surface area of the hull is FAR greater than the fore/aft plane area and that is the main source of the 'suction' that pulls you to the surface. Two: You have the same number of penetrations for bow planes. No, strike that, you have MORE with bow planes as you now have a retraction mechanism that must have a seperate hydraulic source. They are both hydraulically operated. If they are in the sail or bow, they still have to be powered by something. A 688 could have had the ability to rotate the fairwater planes to the vertical for ice ops. It would have required a slight enlargement of the sail but they decided against it for the following reasons: 1) this boat was supposed to be a fleet support boat. Thus under ice ops were not a design consideration. 2) Speed was the PRIMARY factor. A larger ice hardened sail would have increased the wetted hull area and mass and thus affected the the primary design consideration of speed. 3) a 688 class has a SEVERE handling problem due to sail position and size already. Adding a larger sail would have lowered the critical speed at which these problems exhibited themselves. Again, sail size and wetted area are large considerations in speed and controlability. The sail is large enough to hold the sensors, masts, and then some. The access to the top of the sail takes up more space than you can imagine and it a large factor in sail design. Thus control authority and operational considerations drive the move back to bow planes in the newer boats. Three: About noise considerations. They are retractable for surface through ice operations and for harbour damage considerations. NO submarinier is going to rig in a control surface while underwater. If you have a causalty you are going to WANT those bow planes to help you get to the surface. You are not going to be wanting to wait for them to rig out and possible FAIL when you need them most. They are going to be rigged out once out of the harbor and LEFT that way until you HAVE to rig them back in. Bubbleheads are about having a main system with a backup system with an emergency system for when everything goes to hell. Rigging in the bow planes gets rid of the main and the backup system. NOBODY is going to trust there butt with just the emergency system. If you are down to relying on that then you in DEEP doo-doo already. Also, noise from the water flowing over the bow planes is going to be neglible. If you are going fast enough for it to be an issue on the bow array, you are going to be having enough flow noise over the dome that it will not be an issue anyway.