This may be a stupid question but...

[Illender]

It seems to me that the purpose of rigging in the bow planes on the seawolf would be to reduce the sound signature and to rig them out would improve control of the vessel but sacrifice some quietness.
Am I right? Am I wrong?

Novice question I know, but thats what I am.

[Dr.Sid]

In real world, front planes are used at slow speed. Rear planes force acts in opposite direction then the hull lift force, and at low speeds (under 5kts) the planes force is stronger for small pitch angles. That makes holding depth using rear planes complicated.

You set the planes to pitch up position, but only thing the sub does is that the tail sinks, and sub does only start to rise slowly after you center the planes, or when the pitch becomes larger. Not good near the bottom.

Same way when you set the planes to pitch down position, the tail will raise a lot before the depth starts to increase, which is totally unacceptable when near surface.

On the other hand, front planes force acts in same direction as hull lift, so they are much better for controlling at slow speeds, near surface, near bottom.

I've read about this in one book .. they called it 'Chinese effect' and the speed where it starts 'critical speed'.

At high speed they can be retracted because of drag and noise. Also in harbor operation, they simply are in the way, easy to damage.

However you must distinguish clearly between real world and DW world. In DW I don't remember retracting them has anything to do with noise, or if it affects own sonar performance, or ship movement.
But then I did not test it. Should be easy test to do anyway.

Manual says you should retract them when surfacing through ice. If there was some effect on sonar, I think they would say so in the manual (as they speak about things which are not in the game actually, like wires breaking).

In fact I never bothered with them in DW.

Btw. if anyone is interested in this 'Chinese effect', it can be verified in my sim, even if I didn't know about it in the time I designed the actual physical engine.

[LoBlo]

I believe the main motivation for US subs switching for sail planes to retractable bow planes was the ability to surface through the artic ice without damaging the bow planes. Designs before that mostly had nonretractable planes on the sail, as in the original 688 and Ohio classes.

[Frame57]

I believe the main motivation for US subs switching for sail planes to retractable bow planes was the ability to surface through the artic ice without damaging the bow planes. Designs before that mostly had nonretractable planes on the sail, as in the original 688 and Ohio classes.That is true, but we had the ability to position our sail planes vertically so they would not sustain damage when we broke through the Ice cap. I believe one of the major reasons to remove the sail planes is that you now have less hydraulics and resulting hull penetrations to deal with. Also more room in the sail structure for other mast applications.

[Dr.Sid]

Other reasons I know are:

Sail planes cons:
- useless when surfaced
- harder for controlling sub in PD with high waves, can occasionally breach the surface.
- low pitch effect, can't work to counter rear planes jam

Sail planes pros:
- do not hinder harbor operation
- away from sonar
- can have single axis going through both planes
- interestingly again low pitch effect, making it easier to control depth alone

[Bubblehead Nuke]

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.

[LoBlo]

IPlanes 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

Then why not bow planes AND fairwater planes? Bow planes for casulties and fairwater for dept control and you have your backup if the other breaks...:hmmm:

[Bubblehead Nuke]

Then why not bow planes AND fairwater planes? Bow planes for casulties and fairwater for dept control and you have your backup if the other breaks...:hmmm:

You would have to have a larger sail to support the vertical capability needed for the fairwater planes to punch through the ice. Larger sail = slower speeds and other issues.

You would also have a more complex helm station with 3 controls instead of two. There would be more hull penetrations to support both systems as well.

I did not say bow planes could not hold PD, it is just that it was more difficult and took more finese. To be totally truthful, with the drive-by-wire systems that the newer boats have, it is probably just as good if not better than fairwater planes.

We liked redundancy, but there is a minimalization aspect to be taken into account as well.

[Frame57]

I agree with the depth control analysis provided by BN. I think the Seawolf and Virginia class boats have a bow plane control system that is in the superstructure and not in the hull itself other than hydraulic lines routing to it. I am not 100% on this as i heard this discussed at the Submarine league symposium. I think it would be a simple Ram/yoke design.