David,

This is coming from a person who has been qualified in submarines for almost 20 years, and have served on 2 fairwater (sailplane boats) and 1 bow plane Boat. Qualified as diving officer on 2 of those boats, the Bow plane and one Fairwater plane boat. The planes do not see the water first, the flow is simultaneous on all surfaces. The Fairwater planes are good for shallow depth control to about 4o feet, above that they are out of the water and useless, they are also useless at high speed because the hull disrupts the flow under the planes and destroys the lift causing indeterminate results. This is why they went BACK to bow planes. Bow planes are good shallowdepth controlat slow speeds.At high speed, they are not used because they are not big enough to be effective. The are only 9 x 9 feet on a 688 class submarine. The stern planes have a hell of alot more surface area than the bow planes, and will cause largeship anglr changes with a small ordered angle of attack.The hull is the biggest control surface and using the stern planes to change the angle of attack of the hull, and the main propulsion plant is how depth changes are made. Nuke is right, you could never recover a jammed stern planes with the bow or fairwater, the only way to do it is all back emergency and possibly blowing the fwd group. The stern planes are way to effective and have wayyy to much surface area over the fwd planes.Ilike the fwd planes for depth control at PD, anything below PD, I would use stern planes and ships angle to change depth, Rule of thumb for depth changes, less than 100 feet + 5 degrees angle on the SHIP.Anything over 100 feet = 5 degrees + 5 degrees for every 100 feet up to what the CO says he wants useually 15 or 20 degrees of SHIP angle, Torpedo evasion or radical manuevers will call for angles greater than 20 no matter what the depth change. Fwd planes are never touched during these depth changes, except to maybe help arrest the ships vertical velocity occasionally.

R/
Tim