Disney Nautilus Project, 66"

[toppack]

I've read several places that one of the main problems with Nautilus design, is the the Dive-planes are Not efficent or effective (poor pitch control).
It appears to me that they are designed Wrong. Their pivot shaft is too close to center of DPs, it should be much closer to leading-edge. With pivot point in center, the leading-edge is driving boat in opposite direction, than the trailing-edge is, canceling each other out, and acting as a brake. (since water is flowing above and below horizontal fin structures in front of DPs)
Why has no one seemed to notice that before? :confused:
I guess they are just copying the original Goff design?
Click Pic:

[He Who Shall Not Be Named]

I've read several places that one of the main problems with Nautilus design, is the the Dive-planes are Not efficent or effective (poor pitch control).
It appears to me that they are designed Wrong. Their pivot shaft is too close to center of DPs, it should be much closer to leading-edge. With pivot point in center, the leading-edge is driving boat in opposite direction, than the trailing-edge is, canceling each other out, and acting as a brake.
Why has no one seemed to notice that before? :confused:
Click Pic:

The problem is that the strakes they are set within blanket them out from coherent water flow.

David,

[toppack]

The problem is that the strakes they are set within blanket them out from coherent water flow.

David,

Yes, Moving the pivot shaft further forward would also get the trailing-edge further up/down into the water flow, giving even More pitch control. But the cancelation effect, of it being in center, is the main problem, tho.
High torque servo will be needed, with so many dive-planes, but that's no problem with such a large model. May need a very large WTC for everything, tho. I may have to design my own WTC for this project, but I'll check the 3.5"er when I get it, it may work? (I don't plan to put in a full-width diorama in saloon area)

[junglelord]

Here is a wonderful Jet Nautilus. It wants to dive as does the SeaView.
That led this man to run a two voltage system. It runs surface on one voltage and submurged on the higher voltage. It uses bilge pumps as its jets, what a cool idea.

http://www.rcgroups.com/forums/showthread.php?t=985013

[toppack]

Thanks, Interesting videos.
Are there any closeups of it's control surfaces anywhere?
That's what I would like to see?

[junglelord]

Ask and thou shalt receive.

http://www.rcgroups.com/forums/showthread.php?t=982321

[toppack]

I did't see any Info on control surfaces? Did I miss it?
I'll be using a prop (original style) with electric motor.
Jet is a little too Radical for me. :D LOL :D

[junglelord]

I love his bilge pumps. Incredible idea. As far as control surfaces, I believe its only rudder. I think he did mention that when it dives it can go deep so he must put it back to lower voltage to surface. Still while not perfect is another idea of good thinking and using current items concerning the bilge pumps.

[Nuke Power]

ive seen this one run before. I doent have a rudder. It has jets to control its port and stab movement.
As far as dive plane efficiency. I do not believe it is a matter of where the pivot point is, more like david says. Since it retracted inside that surface it is not cutting into the slipstream of the model. YOur suggestion will require a short throw control horn with a good strength servo for a model of this size.

[toppack]

ive seen this one run before. I doent have a rudder. It has jets to control its port and stab movement.
As far as dive plane efficiency. I do not believe it is a matter of where the pivot point is, more like david says. Since it retracted inside that surface it is not cutting into the slipstream of the model. YOur suggestion will require a short throw control horn with a good strength servo for a model of this size.

Thanks for the Info on jet version.
I'm sure I'm correct about the pivot-shaft location. As an example: Look at the flying-tail on modern aircraft. Only about 10% of their area is in front of pivot-point. Just enough to form the leading edge, for flutter-control and control-force balancing (which are not needed in a subs DPs).
I can't think of a good way to prove it, without actual demo comparison testing and i'm definitely not going to build one with shaft in center to prove it. :D LOL :D

[Nuke Power]

Not so sure about that. If you compare the picture with say 2 dive planes, both at the same angle, there is no difference in the overall force that will be created by the plane due to a change in the location of the picot. The total surface areas will remain the same as will the total force created.

The difference should come in when the plane itself enters into the slipstream created by the surfaces of the hull.

Since in the second example the plane is attached higher up it is able to extend more of the control surface past the laminar flow region allowing for more control. This all goes out the window ofcourse if there is something on the hull causing turbulent flow prior to the control surface.

[toppack]

Yes, the main difference is the thick fin or strake, (which most craft don't have), in front of the DPs dividing the water flow and the Long leading-edge acts as a dam forcing model in opposite direction and slows it, due to poor flow there.
Moving the shaft will Not change the appearance much and it should improve pitch control, at least a little bit, so I'll give it a try that way and see how it does. :)
I need good pitch control, since I'm thinking about making it a semi dry-hull model (internal-sealed-box), with dive-planes and forward speed only, for dive capability.

[Nuke Power]

you would probably get more effect from adding a weight on a sliding tray inside the boat. That way you could change the boats CG causeing it to dive. I have seen this done very effectivly and have a similar system in my ohio to compensate for the missile weight once they have launched. Using this method you could even eliminate the need for the plane... just food for thought.

[toppack]

Yes, I've heard of the shifting weight method but was wondering how complicated it would be to operate in a 5 or 6 foot long model?

[Nuke Power]

It so easy a cave man can do it.