Stern planes. Which way up?

[mermaid]

I've noticed that the 1/72 Revell Gato stern planes have an asymmetric cross section. The underside (as installed according to kit directions) has much more camber than the topside. This does not make sense to me since at neutral plane position, the plane would apply a downward force at the stern. This would tend to raise the bow. A crash dive would be hampered as this downward force at the stern would have to be overcome by increased plane down angle. It would make more sense to install the planes with the more cambered surface up. This would tend to depress the bow and aid in diving. I've looked around in my documentation and have found that the stern plane section appears close to symmetrical on the prototypes. Comments?

[g2tiger]

Looks like the rounded side

Looks like the rounded side goes down per the pictures of Big Daves boat as posted else where on this subject. I will most likely make mine the same as Dave's unless someone can say different.

Respectfully,

Charlie

[mermaid]

http://www.subcommittee.com/forum/icon_exclaim.gif I've talked this over

I've talked this over with Mike Keating. The Revell stern planes are definitly wrong. Mounting them upside down will be more prototypical. Mike sent me this the other day. Sorry that the image is so large. This is the first time I've tried posting an image on this site! You might want to print the plan.

[g2tiger]

try this link, may not

try this link, may not be much help
http://images.google.com/imgres?imgurl= ... D%26sa%3DG

It

[mermaid]

http://www.subcommittee.com/forum/icon_biggrin.gif u2tiger: I have saved

u2tiger: I have saved the entire series of Drum images. I sent the image
that you just posted to Mike. He says that when Drum was adapted as a
museum boat, the stern planes were probably replaced. They certainly don't
look like what he remembers on the boats in service. Take a close look at the stern plane profile on this view of Bonefish. I think you'll see what I
mean.

[g2tiger]

what it looks like

Mermaid,

You know, in the photo you supplied the stern plane actually looks like it might be a copy of a dolphin's rear flipper. To me the plane looks sort of bowed in a way like the gull wing of an F4U Corsair fighter plane.

[mermaid]

http://www.subcommittee.com/forum/icon_biggrin.gif It's an optical illusion.

It's an optical illusion. The planes were built with a straight taper from the root to the tip.
Refer to the plan that I posted. What might be fooling your eye is the slight under-camber near the tip.

[tmsmalley]

This is from the "SS212

This is from the "SS212 Class Guidance Docking Plan" sheet I have.

[tmsmalley]

...and this one is from

...and this one is from a similar US Navy plan I have for the SS-417...

[mkeatingss]

Stern Planes

Dave Merriman, and I, beat this subject up, for a couple of days. Both he, and I, qualified on the old Diesel Boats.
I have no doubt, Dave will correct me if he disagrees, so here goes.
Revell got the basic shape fairly close, but, apparently, turned them upside down when they put the guide pin on. The flat side should be the bottom.
Tom Walkowiak, at Floating Drydock, is, also, one of the old "Conch Squadron" and Qualified in Submarines. He has a good drawing of the stern planes.
Strictly from memory (I can't find my Quals notes), I believe, it had a vertical thickness of 12 inches (1 foot) at the root (nearest the skeg) and tapered down to around 2 or 3 inches at the tip.
Also, IMHO, it was an airfoil shape, not quite as flat as Revell made it, on the bottom (assuming theirs is upside down).
I've gone through everything I have, and many of the Navsource photos. But I haven't found what I was hoping for, absolute proof. So, I could be wrong, but, so far, I feel comfortable with what I have found.
The Floating Drydock agrees with what I remember, from messing around on Atule's (Balao Class) stern planes (while in dry dock) and diving around Amberjack's (Tench Class) planes.
But, at my age, memory ain't what it used to be. So, take it for what it's worth.
Mike K.

[mermaid]

http://www.subcommittee.com/forum/icon_idea.gif Just a thought people.

Just a thought people. I could be full of beans but here goes. One may wonder why the Gato/Balao stern plane section
is designed to place an upward force on the stern even with the planes at neutral. Well, one obvious reason is that in a crash dive situation, lifting the stern will tend to depress the bow and less down angle on the plane is required to dive. Less down angle translates into less drag thus improving the boat's speed when diving. Once underwater, there would be a tendency of the bow to rise because the thrust line is below the longitudinal axis of the boat and because there is considerably more hydrodynamic drag above the longitudinal axis than below. The fairwater and masts, guns and the deck with all sorts of bumps hatches, companionway etc. add considerable drag. To counter this, the thrust line is angled upwards instead of being parallel with the boat's axis. This tends to lift the stern and depress the bow. I suspect that the additional upward force provided by the stern planes made it possible for the boat to maintain zero bubble with the planes in neutral or close to neutral position. This would have helped improve submerged speed.