USS Iowa

Hey Mikey,

Do you mean just place smaller tube inside the larger one, solder it, rinse and repeat until you get to your prop shaft diameter (i.e. 1/8")?

Thanks,

Micah

 

That is the three brass tube bushing idea. Also mount your tubes so that where your motors are going, they clear your gun stuff. Motors have a nasty habit of ending up right under the interupters. I agree with the others that powering all four looses turning ability. i would power the center two.

 

Thanks for the comments Rob and Tug. I went down to the local hobby shop and picked up subsequently smaller sizes of brass tubing. I am going to try and get the stuffing tubes done by the weekend.

As for powering only the inner shafts, I have another question/solution. A fellow I met in the hobby shop recommended I use a servo and 2 microswitches (I think this is what he said) for the rudder/propulsion. So basically, if the servo turns the rudders less then 60 degree one way, the ship turns with alll four props running. If the servo turns the rudder more then 60 degree one way, then only the 2 prop shafts on the side the rudder is turned towards get power.

Hopefully that makes sense, but what are your thoughts/past experiences.

 

Before you cement that idea into practice, you might want to check out the rule set you're going to be battling in; that might be construed in some capacity as a sort of turning motor, which in Fast Gun/MWC is illegal. I don't know what Big Gun rules are, which I think is the rules you're building this Iowa, at least according to previous posts.

 

Ya, I had thought rules might become an issue with that one. I look ed WWCC rules and the closest thing I could see would be this

A. SPEED CONTROL RESTRICTIONS
• All motors capable of turning a pre-op for propulsion must be set so that they shall not increase
RPM in a turn.
• Radios shall not be set up to allow an increase in RPM over and above that used to set the scale
speed in a straight line nor shall additional props be brought on line remotely.
• A timed throttle system that enables props to exceed their RPM used to set the scale speed in a
straight line is illegal.

But any big gunners out there with more insight would be great!

 

It also complicates things no matter what ruleset you are battling. Try to keep it simple. It is a big boat and you will have many issues to cure. Things will go a lot smoother if there is less "strange" systems to maintain.

IMHO,

 

I agree Rob, it probably making something more difficult then it needs to be. I think I am just going through all the things you all went through when your first started

 

The hobbiest that recommended that 2/4 prop setup is most likely a scale builder and not a combater. The 2/4 setup is common on larger scale ships.

 

Well there is a little glitch in the MWC rules about this, and with the new high capacity batteries, it can be made to work pretty easily. Since my Duke was set up to accept 4 motors, after Nats I plan on trying it out.

In the MWC, you can power all 4 motors, which is legal. The last rule change, which I think was talking about twin screw ships, but this is where I think they messed up, does not say that. Rick and I did quite a bit of testing on his Scheer last year, to come up with the right props, prop spin direction, pinions, and drag disks. Well in the process of making the many changes I noticed different things happening.
What you do is power all 4 shafts, you must use the same props, RPM, and gears, to make it legal. Now on the outer shafts, place your drag disks directly in front of the props, with no spacing between them. These props do nothing for the propulsion since the drag disks cover the props, but the drag disks slow you down. They actually will not draw much power since they are not moving much water.
Now since all the props are powered, place 2 more drag disks in front of the stuffing tube supports on the center shafts, fixed in place. The ships motors will have to turn faster just to get to speed since you have 4 drag disks on the boat, and with the increased prop wash from the center motors, the ship will stop, and turn faster. The extra drag disks are allowed in the MWC, since all props are powered.
As you can see below, the above drive system does not violate any of the current rules.

MWC Rule on drag disks and props.

4) The ship shall be equipped with a scale number of shafts. Each ship must have a scale number of props. Non-powered props must be the same size or smaller than the powered props.
a) In addition to non-powered props, one speed trim disk may be used on each non-powered shaft.
b) If a ship does not have any unpowered shafts, one speed trim disk may be used on each powered shaft.
c) Speed trim disks must be circular, flat, may not exceed the diameter of the drive props, and must be center mounted. Speed trim disks may not be any type of device that is designed to create variations in drag force from one direction to another.
i) Some examples of prohibited devices are: cups, domes, hinged disks, hinged flaps, etc.
d) Props on all powered shafts must be the same diameter and pitch and have the same number of blades.
i) Props used only to reverse the ship may be smaller, have fewer blades, and less pitch than the props used for forward
propulsion.

MWC turning motor rules
Turning motors can be defined as any of the following:Turning off/on motors only when the ship is turning.
Turing motors at different RPMs only when the ship is turning.
Running any drive motor(s) in reverse when the other drive motor(s) are running forward.
Running any drive motor(s) with significant RPM differences between them.
Side of ship thrusters are turning systems.
Using a pump stream to turn the ship is a turning system

 

Here is what I found in our BIG GUNS rules about turning:

Motors or throttles may not be set to increase power in a turn to improve the maneuverability of a ship, or to increase power during acceleration or deceleration to improve the starting and stopping characteristics of a ship

 

Ever since I first saw the post out the Iowa being build, I have had this question running through my mind.
To be historically accurate are you going to put a bathtub in her?

 

Ill see what I can do lol

 

Hi Micah, I'm back!

On the whole propulsion thing, I think that whole idea falls under the "increasing RPM in a turn" category. I could see it as being useful in a scale model, but I don't think any of the local tech officers would approve of that. Best to stick with either powering 4 shafts with the outer props flattened, or powering 2 shafts and leaving the other 2 free-spinning. The Iowas are big, fast boats that are very maneuverable for their size. It won't compare to Fast Gun ships, with their greater speeds and more propwash, but your Iowa will turn pretty good compared to almost any other Big Gun WWII battleship.

 

Hey, well heres an update. We finished cutting the tubes down, sanding the ends, insdes, and outsides to prepare for soldering them into making bushings. Here is a picture of all the pieces ready for the big show.

We have not done the internal layout yet, so the stuffing tubes are not cut to length (thats why they don't look all same sizes). We plan on doing the layout, estimate as best where the motors are, and measure the stuffing tubes accordingly. Once that is complete, we will solder in the concentric tubes and cut the ends off to the correct length.

 

We managed to try it out on on one of the stuffing tube ends, and the picture below is the end result. I put another stuffing tube next to it to put in into perspective.

An issue that I can't seem to fix is cutting the ends at a straight angle. I have tried using a dremel with a reinforced cutting wheel and sanding it, as well as a clamp/jig and a hacksaw, nothing seems to create a perfectly straight edge. Any suggestions?

 

I tend to clean mine up with a bench grinder and then a reamer

 

I throw mine in the lathe.