Turning circles

[Kazzer]

I'm going to compile a chart showing all models and their operating turning capabilities.

Next time you run your models, make a note of their minimum turning circle and post the result here please.

Reason for this? There are many boats out there and a lot of the newbies don't seem to appreciate that something like a Revell Gato is pretty useless in a 12' wide pool. I'd like to give them a better idea of the best boats for the lake and pool.

As an example, the Trumpeter Kilo is a marvelous pool boat, yet the Trumpeter Seawolf has a poor turning circle in comparison. Some paddling pools are pretty big too, so it is important to consider what waters you have before making a commitment to a boat.

[toppack]

You mean the Gato is supposed to turn in a circle ???
Even with it's enlarged rudder, I haven't had it in a lake large enough yet! :D
I'm seriously considering hanging a dust-pan on it's butt. ;)

Turning radius depends a great deal on speed, so calculating it is not going to be easy.
Do you want the measurement in miles, kilometers, hectars or What? :D

[VanguardUK]

I get a reasonable turning circle out of mine at slow speed - you should try an ohio on the surface mate - turns like a super tanker!

[toppack]

I get a reasonable turning circle out of mine at slow speed - you should try an ohio on the surface mate - turns like a super tanker!

The question is, What should we call 'Reasonable' ?
'Reasonable' for some of my surface ships is a hull-length or less. :D
I think 'That' is main thing Mike is trying to determine, for subs.

One of the main factors is if the rudder was made scale size and travel, or increased for either of those? And if Increased, by how Much?

Of course a few subs have 2 motors, controlled separately for steering, to complicate the data even more. (Which is what I considered doing in the Gato, but my favorite Xmitter is not designed for that, so I didn't do it. :( )
My Gato's rudder size was increased about 30% but in my T-class I'm making the rudder about 'twice' scale size, since Mike had Warned me about it's turning problem.

[Kazzer]

I guess you guys are over thinking the problem. It doesn't matter what speed or whatever, the point is, what is the BEST minimum radius you can operate your boat at?

[toppack]

you guys are over thinking the problem.

I think he's saying to 'Guesstamate'. ;) LOL :D

[Slats]

HMS Trenchant - 1/72 OTW Trafalgar with Pumpjet propulsor
best minimum rate of turn surfaced - 5 metres
best minimum rate of turn dived - 2.5 metres

[He Who Shall Not Be Named]

HMS Trenchant - 1/72 OTW Trafalgar with Pumpjet propulsor
best minimum rate of turn surfaced - 5 metres
best minimum rate of turn dived - 2.5 metres

Changes things when that upper rudder starts grabbing water, doesn't it?

David,

[Kazzer]

Changes things when that upper rudder starts grabbing water, doesn't it?

David,

And a new technology develops! You saw it here first folks!

Get measuring!

1. minimum turn circle surfaced
2. minimum turn circle dived

Post results of your tests please!

[Slats]

Changes things when that upper rudder starts grabbing water, doesn't it?

David,

yes it certainly does, and I must say the British T classes have what I call a runt of a lower rudder, its all of only about 1/2 the surface area of the upper one.

The other thing you notice when you run targets as well as subs is the thrust differences from rpm. You go down just a a foot or so and the sub screw tends to be more efficient than the skimmer- a lot lower rpm for heaps more forward movement.

[redboat219]

the Trumpeter Kilo is a marvelous pool boat, yet the Trumpeter Seawolf has a poor turning circle in comparison.

The Kilo's superb turning capabilities is due to it's amazing "fenced rudder." Wonder why the US Navy doesn't use it?

A good follow-on thread to this one would be
"Ways to Improve Submarine Turning Abilities."

[He Who Shall Not Be Named]

Another contributing factor to the improvement of turning rate submerged as compared to surfaced, is the pronounced movement forward of the submarines center of pressure -- a consequence of the sail, which in most designs is forward of the boats center of gravity. The boat becomes less dynamically stable (easier to turn) as the c.p. gets closer to the c.g.

David,

[He Who Shall Not Be Named]

The Kilo's superb turning capabilities is due to it's amazing "fenced rudder." Wonder why the US Navy doesn't use it?

A good follow-on thread to this one would be
"Ways to Improve Submarine Turning Abilities."

The fences do useful work in improving rudder efficiency, but nothing big. The reason the KILO has the high turn rate is the minimal vertical profile of the narrow stern. The SEAWOLF, on the other hand has a very large vertical profile aft of its c.g. because of the big engineering space, anhedrals and pump-jet shroud -- the boat is overly stable about the yaw axis.

David,

[Kazzer]

yes it certainly does, and I must say the British T classes have what I call a runt of a lower rudder, its all of only about 1/2 the surface area of the upper one.

Lower and Upper Rudder on a T Class? Are you referring to the Slippery T's? I never noticed they had two rudders.

[Subculture]

The kilo is also a chubby little boat compared with the Seawolf, which is quite long and narrow, which seems to be a characteristic of modern U.S attack class boats.

I think the best place to look is to nature when considering what you want from a boat. Small reef fish which have to weave in and out of coral invariably evolve a chubby profile, which gives agility at the expense of speed. A Barracuda which requires speed above all else evolves a thin profile, not so agile, but slips through the water well.

One of the most agile and best handling boats you could ever build is one of the earliest- a Holland class. Other boats which spring to mind are the little Delphin midget sub, Deep Quest and a DSRV would make a great pool sub. BTW what happened to that DSRV project you were working up with FX models, Dave. On the slow burner?

Andy